If you are searching for Types Of Chillers, this post should help! Industrial chillers are an integral part of keeping large commercial buildings comfortable during the warmer months. They typically work in conjunction with a cooling tower which helps reduce the overall temperature of the cooling system. There are two main categories of chillers, these are air and water chillers.
Contents on this page:
Types Of Chillers
There are 3 types of chillers that cool things using air, water, and evaporation. Each type may have subcategories based on how each of them accomplish this goal. Technology varies and depending on the age of the building you own or manage the type of chiller you have may fit into one of the following categories.
- Air Chillers
- Water Chillers
- Evaporative Condensed Chillers
- Reciprocating Chillers
- Rotary Screw Chillers
- Centrifugal Chillers
- Frictionless Centrifugal Chillers
- Screw Driven Chillers
- Absorption Chillers
Air chillers can be split in various configurations or used as a single piece unit. Air chillers vary in size from small capacity to 100+ ton models that are used to cool commercial buildings. The difference between air cooled and water cooled chillers is that air chillers use ambient air as the condensing source and a fan that moves the air over the coil. Water chillers on the other hand use water as the condensing source and a pump that circulates water through the condenser out to the cooling tower that releases it into the atmosphere.
Water chillers are mechanical devices/refrigeration systems that are used to dehumidify air and cool fluids in industrial and commercial facilities. They have many applications from process use to space cooling. The difference between water and air chillers is that the water is sent to a cooling tower to cool the water in a water chiller.
Evaporative Condensed Chillers
An evaporative condensed chiller is an alternative to water and air condensed chillers. Most evaporative condensed chillers range from 15-200 tons but one should select a system that is best suited for their individual facility. Maximizing heat rejection in evaporative chillers is done by recalculating the water constantly to provide on-going wetting of the condenser tubes while mechanical fans pull the air over them, which evaporates the water and rejects the heat to the atmosphere.
Sub-Categories Of Chillers
These chillers are sub-categories of the main 3 types of chillers: reciprocating, rotary screw, and absorption chillers. Each have their own design and pro vs. cons. Choosing the right chiller for your facility is an important decision. It will decide how well you are equipped to take care of your industrial process or use the chiller as part of your HVAC system in a commercial building.
Gas is compressed inside these types of chillers with pistons, not unlike a car engine. There are multiple pistons that continue to compress the gas to heat it. The difference is that the hot gas is used inside the system, not simply exhausted out of a tailpipe. The demand is matched by the adjustable intake and exhaust valves that can be opened to allow the piston to simply idle. Idling the piston when demand for chilled water helps manage capacity. This system is very flexible and can cope with the specific demands from load on the system. It is also possible to manage the capacity to match the demand with a hot gas bypass, but it is not considered to be as efficient. Some systems use both capacity control systems which unload pistons but also utilize the hot-gas bypass to match demand.
Rotary Screw Chillers
The screw compressor is also known and a helical compressor. Inside the stationary housing it contains to mating helically grooved rotors. Direct volume reduction is achieved when the helical rotors rotate. The capacity of a rotary screw compressor varies between 20 and 450 tons and is controlled by a sliding inlet valve or variable speed drive.
Centrifugal Compression Chillers
One of the main features of the centrifugal compression chiller is that they offer a high cooling capacity in a compact design. They operate via an impeller, much like a water pump. The impeller compresses the refrigerant. These chillers can be outfitted with both variable speed drives and inlet vanes which are used to regulate the control of the chilled water capacity. These are high capacity and can handle 150 tons and up.
Frictionless Centrifugal Chillers
Much like the regular centrifugal design these operate via the same principles but do so with magnetic bearings. The use of magnetic bearings eliminates the need for lubricant and features variable speed DC motors. These motors are typically direct drive and attached directly to the chillers. The capacity of these chillers range anywhere from 60 to 300 tons.
Instead of utilizing a mechanical compressor the absorption chillers use a heat source to be the driving force behind the refrigeration cycle. These chillers typically use two liquids, one to cool and one to absorb. The absorbent liquid is usually ammonia or lithium bromide, and the coolant is usually water.
The two liquids are separated and recombined during the absorption cycle. Due to the low pressure conditions in the chiller water can change phase easily. Water and the absorption liquid also perform well in chillers because of their natural properties of affinity.
The refrigeration cycle starts with the heating of the combined liquids. This boils the water out of the absorption liquid at a high pressure. The next step is sending the refrigerant water vapor past a condenser coil where the heat is rejected and the water vapor is phased into a high pressure liquid. Then the high pressure liquid is passed along to the lower pressure evaporator where adiabatic flash evaporation returns the water to a gas. This absorbs the heat from the water that needs to be chilled. The last step is the concentrated absorption liquid is sent back to be recombined with the lower pressure water vapors coming from the evaporator.
Where Are Chillers Used?
In the industrial world there are millions of machines which generate incredible heat. For these machines not to overheat and melt themselves they must be cooled. This is what a chiller is designed to do. Chillers are used for processes that operate at 60°F or lower. For processes which operate at 85° or higher cooling towers are a better fit. Listed below you’ll find some of the common areas in which chillers are used:
Cooling systems are more than just a matter of comfort in Arizona, they are matter of health and safety. For commercial locations cooling expenses typically make up about 30% to 50% of the energy costs. With the cost of electricity always on the rise and the phasing out of HCFCs and CFCs there is an incredibly high demand for replacing large commercial air conditioning and refrigeration systems with chilling systems.
Chillers used in plastic fabrication typically take on one or both of two roles, cooling the plastic products and cooling the machinery used to make them. The products which are blown, stamped, or extruded. The chiller units are also used to keep the barrel of the extruder, and hydraulics of the molding machine cool. This not only saves on energy but it also helps extend the life of the plastic fabrication equipment.
Medical facilities, especially those which do MRIs, laboratory testing, scanning, and blood cooling all rely on chillers to get the job done. The scanning equipment such as MRI machines produce a lot of heat that must be dissipated quickly and safely to preserve the condition of the equipment.
Chiller play a critical role in high volume printing houses. There is a lot of heat generated by friction through the printing rollers and as ink is dried in ovens. To keep the rollers in good condition and freshly printed paper in good condition chillers are used. They remove the heat from the process and keeps the parts and paper in good condition despite the high heat conditions.
A common step of many types of beverage production is cooking, mixing, and pasteurizing. Whether its soda, beer, milk, or other drinks the beverage industry relies on chillers to remove heat produced by these processes.
Lasers are fast becoming a more common element of production, and one that produces a lot of heat. To keep the lasers and products they cut cool chillers are integrated into these systems.
The rubber industry relies on chillers to cool the multizone water temperature control units. This keeps the rubber mill, rubber extruder barrel, bambury mixers and calendars cool and working properly.
Where Are Chillers Installed?
Chillers are usually located in mechanical rooms where other industrial equipment is installed. In other cases the chiller may be outdoors or between the cooling tower and process that requires chiller. This usually depends on the application, the size, and type of chiller and the compressor. No matter where they are they will need regular chiller maintenance to operate efficiently. All Kote Lining, Inc. offers full service cooling tower and chiller maintenance to locations all over the Phoenix Valley.
Phoenix Valley Chiller Repair & Maintenance
All Kote Lining Inc. does far more than just apply protective coatings to your chiller tubes, chillers, and cooling towers. We service and repair chillers in the Phoenix area. We can help you get the most out of your commercial HVAC system by helping maintain the cooling tower and the chiller systems to ensure they are performing their best, and using as little energy as necessary. Give us a call today if you need repairs or service on your chiller system.
This chiller maintenance checklist will help you ensure you catch all of the important areas of your chiller system. In this post we’ve provided an air cooled chiller maintenance checklist as it is the most common design.
Download & View our Chiller Maintenance Checklist PDF
Air Cooled Chiller Maintenance Checklist
Follow this list as you inspect and maintain your chiller. Each item is important and diligent chiller maintenance will save money and make the system last longer.
- Inspect water inlet and outlet for leaks
- Clean out and inspect the sump for corrosion
- Cooling coils need to be inspected and surfaces cleaned. Check for leaks, corrosion, or bent fins
- The zone control actuators should be inspected, cleaned, and all adjustments made
- The compressor needs various areas checked, these include: refrigerant charge, vibration, crankcase heater, oil levels and changes, operating temperatures, and if there are any leaks of refrigerant or oil.
- Condenser fans should be cleaned, bearings need to be checked for wear and lubricated, and belts and couplings need to be checked and tightness checked or adjusted as necessary.
- The condenser coil should be check for corrosion and leaks and all finds or combs need to be checked for bent sections.
- The electrical disconnect should be inspected for proper operation and the contacts should be inspected and cleaned.
- The exhaust air damper needs to be inspected for proper operation, have the bearings lubricated, and calibrate or adjust it for optimal operation.
- Return air dampers also should be checked for proper operation, calibration, and bearings be lubricated.
- The fresh air damper should also be inspected, calibrated, and bearings lubricated.
- The filter dryer also should be inspected and any old, dirty, or damaged filters be replaced.
Chiller Maintenance Tips
The simple fact is that the chiller makes up for a significant portion of your electricity usage, even at peak performance. If you’ve got maintenance issues it can easily use an extra 10%, which hurts the bottom line. While technology has improved to remotely monitor chillers and technology has produced more durable and efficient parts, maintenance is still key.
Maintain A Log Daily
Knowledge is power and saving power is a big deal when it comes to chillers. Recording operating conditions such as flow rates, pressures, fluid levels, and temperatures helps build a useful record of your system. While it was standard to do bi-monthly checks today’s continuous monitoring technology allows you to keep accurate daily logs that will help you narrow down maintenance issues before there’s a bigger problem.
Condition Your Water
Corrosion and scaling are always a challenge in air cooled chiller systems. Treating the water in your system helps cut down on corrosion, scaling, and the growth of biological contaminants such as Legionella. All of these issues can let to a decrease in heat transfer caused by fouling and diminished heat transfer due to build up inside of pipes. It’s important to continually monitor your chilled water loops remotely and visually inspect them annually.
Clean Heat Transfer Tubes
A big part of the efficient operation of chillers relies on clean heat transfer tubes. If your system has mud, minerals, algae, or scaling it will coat the inside of the tubes and insulate them. While insulation is great at keeping heat out of a home in the summer the heat transfer in chillers is the cornerstone of how the system functions. Neglecting your chiller tube cleaning will end up inflating your operating costs and likely result in additional maintenance and more frequent downtime.
Maintain Refrigerant Charge
Your chiller’s ability to cool relies on having the right amount of refrigerant. To ensure your systems optimal efficient performance make sure you’ve got the right level of refrigerant. If there is air, moisture, or leaks in your system it will impact it’s performance. With insufficient refrigerant it will take more electricity for your system to perform the same cooling effect.
Provide Cooler Water
Providing cooler water for the condense improves the chiller’s performance. It will not have to work as hard to condense the water and will run more efficiently. In some cases this technique can compensate for problems with coils. While this does fix the problem it is a temporary solution as the chiller must work harder for the same effect.
Chillers function on the principle of condensing refrigerant to cool. If moisture or air leaks into the system it introduces non-condensable elements into the system that rob it of efficiency. The percentage can be as high as 7% below the rated performance of the chiller system you have. When considering how much energy a chiller uses to begin with and extra 7% adds up quickly.
Maintain Appropriate Flow Rate
The rate at which your chilled water flows through the chiller does impact the chiller’s performance. If it is too slow it lowers efficiency. Too fast and it will cause erosion, vibration, and noise. It is best to keep the flow rate of your chiller somewhere between three and twelve feet per second. The exact speed will depend on your chiller’s design and the load needed by your location.
Upgrade To Variable Speed Drives
In most cases the chiller motor is the largest draw on electricity in the entire building. Single speed drives are on or off and cannot adjust for the difference in load the system is running under. In contrast a variable speed drive saves energy as it can adjust the speed to match the load. This saves a significant amount of energy in your chiller system. In addition variable speed allows the system to ramp up more smoothly in the case it is turned on in an emergency situation.
Check Oil In Compressor
If your compressor uses oil make sure you send a sample of it for inspection at a laboratory once per year. Due to the hermetically sealed nature of a close refrigerant system the compressor oil should only be changed if the lab deems it necessary. If there’s excessive moisture it can point to there being a problem with purging the system effectively. If the oil is changed ensure the filters are tested and replaced when there are pressure drops. In the case your system uses magnetic bearings and is frictionless your system will not have compressor oil.
Inspect Motors & Starters
You can save energy and downtime if you inspect your motors and starters. To do so inspect the sensor calibration and safety on the microprocessor controls. Also take the time to inspect the wiring and connections in your chiller system at common wear points and hot spots. Pay attention to signs of refrigerant leaks and test motors for insulation faults.
When To Inspect Chillers
Chillers should be inspected and maintained at least 2 times a year in areas where they are only used during the cooling seasons, or 4 times a year in areas that cool in all 4 seasons. Quarterly inspection helps your chillers, HVAC system, and cooling towers last longer and run more efficiently.
Maintained Chillers Operate More Efficiently
Using this checklist you can get better performance out of your chiller and cooling system. The better maintained your chiller is the less energy it uses, and that saves you money on utilities. As the chiller and HVAC system is one of the largest draws of electricity in many commercial, industrial, and medical facilities it is important to inspect, maintain, and repair chillers. Regular inspection and chiller maintenance will help save money and make the system last longer.
Chiller Maintenance in Arizona
If you have a property such as a commercial building, medical facility, or industrial site that uses chillers for processes or HVAC All Kote Lining, Inc can help you take care of the chiller maintenance you need to keep your energy use down and make your equipment last longer. We inspect, maintain, repair, and line chillers with the most durable coatings available. Give us a call today to find out what we can do for your company at 480-966-4446.
If you’re searching for Heating and cooling technologies and want to understand how they work this article will help you. Common heating and cooling technologies including cooling towers, evaporation coolers, and humidifiers. All of these devices help keep our residential, commercial, and industrial properties warm in the winter and cool in the summer. It is these hard working mechanical systems that make our modern world comfortable and practical.
A cooling tower happens to be used to cool off the circulating water that is used in power stations, oil refineries and chemical plants as well as for large scaled AC units. They are going to be the largest non-residential water consumers. Water that falls through the tower will be cooled because of evaporating and then it is returned to the tower top. The water that will drop into the basin will be about 10 degrees cooler than the water that is returned to the top. Towers will vary in size from large structures to small roof top units. The taller the tower is, the greater the temperature drop will be.
Water that is lost by evaporating, drift and bleed off which is water that is used to carry away the mineral buildup within the cooling tower. Water will need to be added to the system to make up for the loss which is called makeup water. Evaporated water loss from a cooling tower can be estimated to be 3 gallons of water per minute for 100 tons of water cooled. That means that a tower that has 500 tons of cooling will evaporate almost 22,000 gallons of water over a 24 hour period of operation.
A major way to help improvewater efficiency of the cooling tower is to actually being to reduce the bleed off amount. Water can be reduced by 20% or more by circulating the water through the tower a few more times before bleed off happens. This results in a higher concentration ratio. A cooler’s concentration ratio is the measure of water use efficiency. The higher that the ratio is, the more water efficient it is.
Cooling tower bleed off may be used to irrigate plants that aren’t sensitive to high salt content. Another type of option is to send it to water treatment plants. Not only would these options save water, but they may also save money through reduced sewer and water costs.
Use of Sulfuric Acid
Using sulfuric acid within the chemical treatment of a cooling tower will help to prevent scale buildup, so that the water is able to circulate more times before it is discarded or any makeup water is added. If the sulfuric acid treatment isn’t practical or feasible, then carboxylated polymers called carboxylates may be used in order to control the pH and prevent scale. The carboxylate solubility is double without any treatment but less than using sulfuric acid.
A conductivity controller is a device will automatically control the blowdown based on the number of concentration cycles that may be safely done. The resulting conductivity which is measured in microsegments per centimeter or uS/cm. The conductivity controller may continuously measure the conductivity of the cooling tower water as well as the discharge water whenever the conductivity set point has been exceeded.
Evaporative coolers also called swamp coolers will increase the humidity of incoming air that is being drawn into the building and decreases the temperature. After a bit of time, recirculating the water in the evaporative cooler will assume the entering air temperature. This temperature is going to be the lowest temperature that the air may be cooled too.
The principal opportunity for conservation of water that is used is to help reduce the flow of bleed off from the coolers. Normally on a small stream of bleed off is needed for operation, however excessive amounts of water are often bled off. This wastes water and impairs the cooling efficiency of the cooler because the water doesn’t get as cold as possible.
There are 3 common types of evaporative coolers: dump pump, recirculating, and non-recirculating. The bleed off from all of these can be used to irrigate plants that aren’t sensitive to high salt content.
Recirculating Evaporative Cooler
This cooler type, the water will run off the pads and is captured and recirculated multiple times before it is discarded. A small amount of bleed off will be needed to control concentrations of contaminants within the water and to prevent damage to the cooler pads, which allow it to effectively operate. Bleed off valves may be adjusted to discharged the minimum amount of water needed. Recirculating evaporative coolers will only use about 3 gallons of water per hour.
“Dump pump” Evaporative Cooler
A dump pump will automatically empty and refill the water collection pan every few hours.
Once-through Cooling for Equipment
Within dry climates, equipment may be cooled using single pass or once through water. This is a very intensive water cooling process as the water is passed through and it cools the equipment, the water is discarded. Equipment that may be cooled by once through water are x-ray machines, degreasers, air conditioners, vacuum pumps, welders, hydraulic presses, air compressors, viscosity baths, condensers, hydraulic equipment, and rectifiers. Most types of water cooled equipment may be replaced by air cooled, energy efficient models. Water usage may be reduced through recirculation by using water from a non-portable source and by reusing the once through water for other purposes like irrigation or cooling towers. These practices help to save water and may also save money by decreased sewer and water costs.
In active management areas in Arizona, the ADWR prohibits using once through cooling water by industries that have their own wells unless the water is being reused.
Boiler & Steam Generators
Boilers are used within large heating systems of in those industries where a large amount of process steam is used. Water will be added to a boiler system to make up for any water loss and to help replace water loss whenever the boiler is blown down to remove solids that have built up. Whenever it is practical, steam condensate will need to be captured and returned to the boiler to be reused as makeup water. Condensate return systems will save water, reduce costs of pretreating boiler feed water and reduces energy use. Boiler operating costs could be reduced by 70% by installing a condensate return system. Water that is consumed by boiler systems may vary depending on the system size, how much steam is used, and the amount of condensate return.
Expansion tanks help to provide a cushion of air for expansion of water when it heats. This helps to save water in 2 ways. It helps to prevent the pressure relief valve from being opened and discharging water to help relieve pressure and then it eliminates the need to use cold water when mixing valves to cool blow down because it will be condensed and cooled in the expansion tank. In a steel expansion tank, the air and water will touch each other. In a bladder expansion tank, the water and air will be separated by a diaphragm.
Humidifiers are often used to add moisture to the air through evaporation, which increases the relative humidity levels. There are 2 major types of humidifiers: central humidifiers and room humidifiers. A room humidifier is a self-container unit that isn’t connected to a water supply line. The reservoir is manually filled. A central humidifier will be connected to a central heating system and water supply line. The reservoir is automatically filled.
Humidifiers will have a continuous bleed off system and waste water. In these particular humidifiers, a constant water stream will leave the reservoir and will enter the sewer system at the same time that a continuous stream of water will fill up the reservoir. However the use of a Recirculating humidifier will not constantly drain and replace the water. There are some concerns about sick building syndrome. An alternative to this would be to reuse discarded water for another purpose like irrigating plants instead of sending to the sewer. Another option is to adjust the discharge amount to the minimum amount of water to avoid too much bleed off. Timers may be used to turn off and on the humidifiers based on your seasonal needs, or to control whenever the water is pumped out of the reservoir to remove mineral buildup.
Mist Cooling Systems
These types of systems have become readily available to home owners and businesses as a great cooling option in areas that have low humidity and high temperatures. Water will be pumped through the system and released as a fine spray that evaporates which form a cool barrier against dry, hot air. Each misting nozzle will only use about a half of a gallon of water each hour. In order to conserve water, the system should only be used whenever people are using the area. There are some systems that have sensors that turn off the misters when no one is around, or there are off/on switches that can be activated when needed. It is also best to use the misters that have nozzles that may be independently controlled so that you are able to direct the nozzles right so that the system will only cool the intended areas and turn off misters when it is too humid or windy for them to work properly.
Phoenix Valley Cooling Tower & Chiller Maintenance
If your commercial or industrial location features a cooling tower or chiller keeping them in good working order is critical. Not only is controlling biological growth required by law, but neglecting the condition of your chillers or cooling towers reduces their life expectancy and diminishes performance. That means they are using more energy, impacting your bottom line, and wearing out more quickly. Maintain your industrial heating and cooling equipment with service from All Kote Lining, Inc.
If you’re searching for ways to reduce energy costs in commercial buildings or energy saving tips for commercial buildings you’re likely a building owner or business owner. Reducing energy loss in your commercial property will help lower your overhead and it is fast becoming a national energy imperative. Many of today’s retrofitting energy saving improvements could culminate into a 29% drop in energy usage by 2020. That could translate into energy savings adding up to $290 billion dollars and also reducing green house gases by an incredible 360 million tons!
Retrofitting & The Law
There are some regions of the United States have passed initiatives that require energy saving retrofitting that reduce energy loss. For areas that do not have such requirements the savings on energy is a major motivation for most business owners to act even without a requirement to do so. Larger properties that have chillers and large HVAC systems consume an enormous amount of energy that constitutes a significant portion of everyday overhead. Reducing that cost will mean freeing up funds to invest in the business or other avenues.
Five Areas To Reduce Energy Consumption
There are five major areas that you can take action to reduce your overhead and energy consumption in your commercial building. When businesses save money on the everyday expenses it means major savings which can be invested elsewhere.
Chillers and boilers in commercial buildings are some of the highest energy consuming elements. They can add up to a whopping 20% of the overall energy usage. In hot climates like Arizona chillers play a critical role in keeping commercial spaces comfortable and safe during summer. Chiller maintenance helps keep the system more efficient and reduces the energy needed to do its job effectively. If the chiller is worn out it can also be replaced with a newer more energy efficient unit. Boilers are also important for colder months and colder climates and must be maintained to run at peak efficiency and draw as little energy as possible.
Commercial Building Retro-Commissions
We all know that our vehicles need regular maintenance like oil changes, replacing belts, new tires, etc. Commercial properties also need to be regularly maintained to stay efficient and use as little energy as necessary. Adjusting small things such as when the heat or air conditioning are ran can add up to significant savings in energy and budget. As buildings age they also may be outfitted with outdated or broken down designs for energy efficiency. Retro-commissioning is a the process where the building will be evaluated for energy efficiency and improvements made to reduce the cost of operation.
Advanced Energy Technology
Building materials, light bulbs, and even windows have taken incredible leaps in recent years. This is a great opportunity for older commercial properties to take advantage of much more energy efficient technology. Commercial property energy audits are the best way to start improving a building’s efficiency. Energy solutions discovered by the audit may include upgraded lighting systems, improving the building’s envelope, or the installation of renewable energy solutions. These improvements will help building owners in the short term and improve the value of the building for future owners.
Steam Trap Improvement
Poorly designed, maintained, or old steam trap systems are a common issue for older buildings and hospitals which rely on boilers. Some of these properties have hundreds of steam traps that control the steam and condensation inside the steam system. When they are not properly maintained they can end up stuck open, and return steam into the boiler causing a decrease in efficiency. Boiler maintenance companies can help keep these steam traps working property and the boiler working at peak performance so it consumes as little energy as possible.
Upgrading & Evaluating Energy Management Controls
When energy management controls are either outdated or programmed improperly it can lead to terrible energy efficiency. While the controls may seem like they do their job they may be leaving your building far below its potential and be costing you money. Upgrading to newer more advances energy management controls or having your existing controls reprogrammed can save energy and money. When the power system is programmed correctly and climate control is optimized the savings can be incredible.
(Bonus Way) Commercial Solar
Installing commercial solar panels can help you save a ton of electricity for your building. There are many benefits of solar power for business including: reduce electricity costs, instant ROI, reliability and maintenance free, lock in your power costs and more. Depending on your business type, you could save thousands, if not millions, by installing commercial solar panels on your facility.
Budget & Environmental Benefit
To save energy building owners and property managers should evaluate their buildings in these 5 important areas so they can identify which are the highest priorities for their specific property. Tuning, adjusting, and retrofitting the building will help reduce the energy consumption, potentially save enormous operating costs, and reduce the building’s carbon footprint.
If you’re looking for the difference between a cooling tower this post is for you. While both play an important role in commercial buildings or industrial processes they do have different jobs to fulfill and work together.
What is the difference?
Both cooling towers and chillers are designed to remove heat from liquids. The liquids are used to cool industrial processes like power stations or in HVAC applications in large commercial buildings. Both of these pieces of equipment vary depending on their role in a setting, which components they are comprised of, and the type of equipment they power and keep cool.
Chillers differ in that they absorb heat from the coolant, which is usually fully contained within the cooling system. The chiller transfers the heat to the surrounding air.
A condenser discharges water to cooling towers that then removes the heat. This is done via air liquid contact by spraying water onto surfaces with fans blowing air through the tower. By doing this the heat in the liquid is transferred to the air passing through the tower.
Cooling Tower & Chiller Types
Cooling Towers are divided into to types which are natural draft and mechanical draft. Natural draft cooling towers are enormous structures commonly associated with nuclear power plants where the exhaust air is let into a tall chimney. As the air rises it begins to cool naturally Mechanical draft cooling towers differ in that they use fans to pull cool air from outside into the system to transfer the heat from the liquid. Chillers are much like radiators and can be cooled by air or water. Water cooled chillers may need more maintenance than air cooled chillers, yet they use much less power.
Cooling Tower & Chiller Major Components
Cooling towers major components include the pumps and basin. The pumps send the water to the cooling towers which creates the cooling flow that cools the facility. Distribution basins collect discharge water from the coolant circulation system.
Chillers consist of compressors, condenser heat exchangers, and evaporator heat exchangers. The component in a chiller that rejects the majority of the heat to the air is the condenser heat exchanger.
Uses & Applications
Chillers are used in areas which will not be affected by the additional heat discharged by it. In fact many installations rely on the chiller to produce heat during the cooler months. Typically facilities to find chillers in include refrigeration and plastic industries.
Cooling towers are found commonly in mechanical processes and electric power generation. Power plants are commonly located near lakes or rivers which are tapped to provide cooling to the water circulating in the system. The water coming out of the condenser in these plants must be cooled to sustain the process.
Efficient Power Consumption
Chillers use compressors and heat exchangers to cool and are not as energy efficient as cooling towers. While the fans and water pumps in cooling towers do consume energy they also provide much greater cooling capacity.
Chillers which use air cooling are also not as efficient as water cooling chillers. We all know that a wet surface transfers heat better than one that is dry. The same principle applies in the case of chillers with a 10% greater efficiency in water cooled chiller units.
Phoenix Valley Chiller & Cooling Tower Maintenance
If you need chiller maintenance or cooling tower maintenance to get the most of your equipment All Kote Lining Inc. is here to help. We can maintain your equipment so it is more efficient and lasts longer. That means you save money as it operates and won’t have to spend money replacing it as soon. Our services are through and can be ordered on a regular basis to ensure your equipment stays in top notch condition.
Call Today – 480-966-4446
Industrial chillers are used in large commercial or industrial buildings. They are much more efficient at cooling these large spaces and work by using a de-humidification or vapor compression technology. How a chiller works is fairly complicated but we will examine is a bit more closely in this post.
How Industrial Chillers Keep It Cool
Vapor back to liquid
When operating correctly the condenser has a twofold role in the industrial chiller. The first step in a chiller is taking superheated vapor and reducing it back to liquid coolant. This process mush transfer enough head from the refrigerant to lower its temperature to convert it back into a liquid form. Once this is done the condensation may begin. The quality of the refrigerant continues to improve as the heat is transferred out of the water, or refrigerant. This process continues until the air has been completely transferred back into liquid. In a perfect world this process is complete by the time the coolant reaches the outlet of the condenser. However to prevent pressure losses and liquid flashing subcooling helps prevent issues with introducing vapor back into the system.
Cooling the hot liquid refrigerant
Even after the condensation process the refrigerant is still at a high temperature and needs to be cooled before it can be reused as a heat transfer medium. In chillers this is done by decreasing the pressure. Physics dictate that if the pressure is reduced in a space that the temperature will follow. So you can count on the temperature to follow if you reduce the pressure.
Temperature Reduction Through Lowering Pressure
To do this in the chiller restriction is a necessary part of reducing the pressure. System loads vary based on a few different elements so the system cannot regulate this depressurization process. The thermostatic expansion valve is responsible for lowering the pressure in the tanks holding the refrigerant that needs to be cooled. This is an adjustable pressure regulator that can adjust for the load of the chiller. The thermostatic expansion valve will not maintain the constant vapor pressure and is only a superheat controller. It simply provides the reduction in pressure necessary to a designated level which is determined by size load, system conditions, load demand, the compressor size, and the thermostatic expansion valve. Some systems require constant evaporator temperature. In these cases a pressure regulating valve should be added to the system. This will help maintain the pressure corresponding the saturation level.
Pressure loss in the thermostatic value can be explained by the mixture of both states of refrigerant. Meaning that when both the liquid and vapor exist in a section of the cooling system superheating or subcooling cannot be achieved. The saturation temperature will always be directly linked to the pressure.
To remove the necessary heat some of the liquid refrigerant must be boiled. This is another process that results in lower liquid temperatures. When the chiller is working properly and subcooling is achieved the difference between the cooled refrigerant introduced into the system will increase the efficiency due to the energy decreased by the boiling of the refrigerant.
The evaporator tubing is the final leg of the refrigerants journey through the cooling system. At this point it is a mixture of both vapor and liquid. Heat is applied to the tubing by having warm air blown over it. This process boils off the last of the liquid leaving only vapor. The last molecule of liquid should be converted to vapor at the evaporator outlet. This means that the vapor at the inlet of the compressor is sufficiently saturated.
This process continues until the space that needs cooling is at the desired temperature. Then the equipment cycles off and waits for a need for it to come back on.
Chiller Maintenance & Repair Phoenix AZ
If you have a commercial property that uses a chiller to keep the building cool you need to make sure that you are getting regular maintenance. This will help prevent repairs and promote better energy efficiency. If there are already problems we repair chillers and can provide coatings to help prevent corrosion of chiller tubes. Give us a call and find out what we can do for your chiller in the Phoenix areas. Call today at 480-966-4446.
Taking things for granted is part of human nature. We rarely consider the way everything works and stays working each day when we go about our routines. The ignition fires up our cars, the coffee pot brews up some motivation every morning and we rarely give the things that make our lives comfortable much thought until they aren’t working. This is no different than HVAC systems. A big part of the HVAC system is the chiller, and the tubes that make it work. Understanding chiller tube cleaning helps us keep our chillers working and our buildings cool during the warmer weather in Arizona.
To keep chillers and HVAC systems efficient they need to have regular maintenance and coatings. It is no small task to care for these critical components of the cooling system for large commercial spaces. Coatings help prevent buildup and cleanings kick out deposits that reduce thermal transfer.
Large commercial spaces use a lot of energy and the chiller can be one of the largest consumer of energy. As the price of energy increases, the savings of regular cleaning and chiller coatings increases. Keeping daily logs, making preventative maintenance a priority, and scheduling regular chiller maintenance will keep your overhead costs down.
Key Chiller Tube Cleaning Considerations
The efficiency of the chiller tubes is completely dependent upon heat transfer. Thermal efficiency is limited by buildup on the inside of the chiller tubes. Most large chillers are comprised of literally miles of tubing which helps achieve the heat transfer in the evaporator and condenser. Keeping the tubing clean therefore is the way these critical HVAC components do their job and use less energy. The best way to keep tubes clean is to have planned outages for cleaning, keeping up with water treatment, and having chiller tube coatings which help control buildup.
The efficiency of chillers drop steeply as buildup develops inside the chiller. It is deposited by contaminants in your water that is recycling through your system and by contaminants being brought in from the air cycling through your cooling tower. The contaminants found in your chiller can range from algae, mud, sand and even minerals that develop into scales that all sap the heat transfer.
The percentages of decreased thermal transfer drop quickly even with what seems like thin layers of contaminants. Even a coating as thin as .0045 can drop chiller tube efficiency by as much as 44%.
Water used in cooling towers and chillers usually comes from local water supplies. This means there can be additives, sand, minerals, and other elements that cause fouling and deposits in chiller tubes. Even the atmospheric conditions around the cooling tower have a significant effect on the quality and contents of the water used in HVAC systems.
This means that there needs to be water treatment in the system to help fight biological growth, scaling, and other deposits. The most contaminated the water the greater need for water treatment and a more frequent and robust water treatment plan.
Chiller Motors & Electrical Components
The chiller motor in your HVAC system is potentially the greatest user of electricity in your entire building. We might obsess about shutting off lights in our homes and offices, but the chiller is responsible for using an enormous amount of electricity to keep our commercial properties cool and comfortable.
Chiller motor maintenance is a critical part of keeping your system efficient and your energy bills as low as possible. The shaft seals, and air vents should be checked and kept clean. All of the insulation, wiring, and connections should be maintained to keep the system running properly and avoid unscheduled downtime.
Methods Of Tube Cleaning
For the best thermal performance it is clear that regular cleaning and maintenance of the chiller tubes is not optional. It is mission critical and should be carried out on a regular schedule by properly trained and equipped chiller maintenance technicians. There are different methods that these technicians use to get your tubes clean and maintain the thermal efficiency of your chillers.
One of the older methods of tube cleaning, is has seen a decrease in use in the last decade. Acid solutions are used in chemical cleaning that soften and break down the scale and deposits in the tubes. The acidic solutions are circulated through the tube bundles and help remove the layers of energy robbing debris.
Chemical cleaning does have the advantages of breaking down mineral scale so brushes can effectively remove them, and it can take tubes back to bare metal. It has lost some of its former popularity because it is time consuming, the chemicals are costly, requires increased training, and the chemicals are dangerous and difficult to dispose of.
Rod & Brush Cleaning
The rod & brush method is very similar to the cleaning of a gun barrel. It is probably the oldest type of chiller cleaning. A rod of metal is tipped with a wire or nylon brush that is larger than the tube. The process generally involves flushing the tubes with water, and then forcing the rod and brush through the tubes. After the rod has been pushed through water is sprayed again to remove any debris.
This is a popular method because it is inexpensive, but it does have some disadvantages. It is labor and time intensive. The chiller might be in an area that prevents the longer rods being used. Smaller sections might have to be assembled as the brush is inserted into the tube, adding to the time of the job. Also the bristles on the brush tend to fold down and end up swabbing instead of brushing. Another limitation of this process can be if the tubes brushed first dry and the debris reattaches before the final rinse is completed.
Rotary Tube Cleaners
Using either an air or electric motor these chiller tube cleaning machines include a cleaning tool that uses water and circular motion to help remove debris. A flexible shaft is set inside a plastic casing which directs water directly to the cleaning head. The tools used with these machines include scrapers, hones, brushes, and buffing tools. This combination of tools is what makes the rotary tube cleaners some of the best at removing deposits, including hard scale. The job is done by one operator feeding the shaft through each of the tubes. Best of all it only takes one pass for each tube.
This is one of the most used, and popular chiller tube cleaning types. It is due to the fact that is it one of the most effective cleaning methods paired with the low cost. The process takes little time and uses less consumables that other cleaning methods. It also only requires one technician, only opening one side of the chiller, and is the best type of cleaning for internally enhanced chiller tubes.
Tube Cleaning Guns
As the name suggests this method of tube cleaning features a gun that uses air or water to shoot a projectile through the tubes. These projectiles vary from metal or plastic scrapes to brushes and even rubber bullets.
This is a popular type of cleaning for light deposits and is very fast. With the right conditions tubes can be cleaned quickly, even in a matter of seconds per tube. It does have the limitation when it comes to the type of deposits it can remove. Harder scaling or stubborn deposits are more difficult or impossible to remove with this method. It also requires the opening of the chiller on both ends to allow the transfer of air as the projectile goes through the tube.
The equipment can be costly to buy and maintain along with some units being somewhat dangerous to operate. The pressure released into the tube might not make it through and be rejected at the operator when the gun is removed. Some units include pressure relief valves that prevent this danger to operators.
On Line Cleaning Systems
Cleaning systems are available for use while the system is active. This means that they help reduce the frequency of downtime. There are two on line tube cleaning types available today. One uses foam balls that circulate through the tubes in the chiller and the other includes the use of plastic brushes that are installed into each of the tubes. The idea behind the foam balls is that they should work through each and every tube in the bundle often enough that they will clean the tubes from becoming dirty. The plastic brush system features plastic baskets which are permanently attached to both sides of the chiller. Periodically the direction of the flow of water is reversed to cause the baskets and brushes to travel the length of each tube, removing debris.
With proper water treatment these systems can reduce or even eliminate the needs for tube cleaning. However these systems are costly to purchase and install. They also are not suitable for chillers that use hard water that promotes hard scaling.
Internally Enhanced Tubes
The only cleaning method for this type of chiller tube is rotary tube cleaning. These chiller tubes are making advancements with thermal efficiency and are becoming more and more common. Internally enhanced chiller tubes are those that include rifling on the inside. Rifling is when spiral groves run the length of a tube. They cause the water to circulate more evenly and provide increased surface area. Both of these elements increase the chiller’s thermal efficiency.
The rifling does mean there are areas that are below the surface of the metal. This means that many cleaning methods are simply not suited for getting into these crevices that increase efficiency. The best type of rotary tube cleaners to use in these applications are bi-directional units. This means that on the way in, and the way out, the brushes can be moving in the same direction as the spiral inside the tube. Specialized heads have also been developed to get into these grooves.
Chiller Maintenance in Arizona
If you have a chiller in or near the Phoenix valley All Kote Inc. can help you extend the life of your chiller and your cooling towers. Regular maintenance and repair keeps the system energy efficient and can save users huge amounts of energy and that means real savings on electricity bills. If you have a commercial space that uses and chiller or cooling tower make sure that you have a plan for maintenance and have All Kote help you with your chiller and cooling tower needs.
Are you searching for “What Are Industrial Chillers?” If so All Kote Lining Inc. has you covered with both information about what they are and can handle any of your chiller repair needs in the Phoenix metro area. Industrial chillers are designated for use as refrigeration systems which cool process fluids. They are also used to dehumidify air in industrial or commercial facilities. Chillers will use either absorption cycles or vapor compression to cool. The water that is chilled by these machines are used for various applications including cooling industrial fabrication processes and to cool large commercial spaces.
Industrial Chiller Types
Each chiller has a rating of between 1 and 1000 tons of cooling energy. There are three main categories or types of chillers, evaporative condensed, water, and air chillers. Each of these types also have 4 different technologies for getting the job done, absorption, screw driven, reciprocating, and centrifugal chillers. Screws driven, reciprocating, and centrifugal are all mechanically driven systems, absorption chillers differ in the fact that it operations via a heat source and has no moving parts.
Industrial Chiller Components
Mechanical compressor type chillers have four basic components stages that the refrigerant must pass through. These are going through the evaporator, then compressor, condenser, and lastly the expansion valve. Evaporators operate at lower pressure and temperatures than chiller condensers.
How Industrial Chillers Work
Chillers work by passing refrigerant, typically water or air, through a series of components to change the condition of the refrigerant to expand and contract. This process results in heat transfer and cooling for the purpose of cooling industrial fabrication processes, or air for HVAC systems in large commercial buildings.
Condensers are the start and end of the cycle for chillers. As the refrigerant passes through the expansion valve it returns to the condenser as a super heated gas. It must be brought back down to the level where the gas is at the saturation temperature. This is the point where the condenser can start condensing the refrigerant back into a liquid. This is done by continuing to transfer heat from the refrigerant to the air. The system will continue until the refrigerant is completely condensed back down. In theory this process happens at the outlet of the condenser. In application a degree of subcooling is expected at the condenser outlet. To prevent liquid flashing subcooled liquid helps avoid pressure losses in the components and tubing.
Lowering Refrigerant Temperature
When the liquid leaves the condenser it is under high pressure and is at a high temperature. Before it can be used as a refrigerant again it must be cooled. This is accomplished by reducing the pressure the refrigerant is under. The relation between the pressure and temperature is a law of physics and you can count on the refrigerant cooling if the pressure is lowered.
To reduce the temperature pressure is reduced by first having a system of pressure restriction. This is accomplished with a thermostatic expansion valve. This is useful as the pressure varies based on the load on the system. A thermostatic expansion valve can adjust for load, pressure, and temperature variations as the system has lower and greater loads applied. This valve will act to lower the pressure, and by affect the temperature of the refrigerant. The valve is limited to only produce a predetermined pressure change that fits with system design and load conditions.
The cycle has dropped in the thermostatic expansion valve. When there is a mixture of both liquid and vapor states of refrigerant Subcooling or superheating is not possible. For this reason any place in the system where both states of refrigerant exist, the pressure and saturation temperature will match.
A portion of the liquid refrigerant must boil to help exchange sufficient heat to lower the temperature of the system. This is another process that results in heat transfer and lower liquid temperature. When there is a large difference in temperature between the liquid and vapor states more refrigerant will need to be boiled off to achieve saturation temperature. This process improves greater refrigerant quality.
The last stage of the refrigerants journey is a mix of vapor and liquid. It passes through the evaporator tubing and warm air is blown over the evaporator. This is where the heat is transferred to the boiling refrigerant. The latent heat gain experience by the refrigerant causes to temperature increase, yet it does experience a change of state. In the best case scenario the last molecule of liquid refrigerant boils off by the evaporator outlet. This is then passed through the to the compressor inlet. This is how the refrigerant is passed back to the start at the condenser.
Phoenix Chiller Maintenance & Repair
If you have a Chiller in the Phoenix valley it needs regular maintenance to work without using too much energy. The tubes need regular cleaning and coatings can be applied to help reduce scaling and build up that rob you of energy. If you need chiller repair we can also help you get your system back up and running. We also work on cooling towers that are commonly associated with chiller systems. We offer a complete maintenance and repair service for all industrial and commercial chillers in the Phoenix valley. Call us today for service at 480-966-4446
Absorption chillers all work on a similar principle, when the pressure system is low the absorption fluid evaporates and the heat is removed from the water parts that are chilled and the absorption solution is then regenerated either by steam, hot water, or exhaust gas.
If it is in a waste energy plant or cogent, it will usually consist of stream fired absorption due to the cost of the steam being lower. If it is in a hybrid and/or higher cost of electricity areas it usually will use the direct fired, using natural gas units. Many users will buy absorption chillers to use as an environmental advantage since absorption chillers do not use refrigerant such as CFC and/or HCFC.
Principle & Mechanism:
As a principle, it does not sound presumptuous to use a burning flame in order to cool something down, however,that is just what is done with absorption chillers. The refrigerant is merely water that acts as a medium and it goes through a phase which causes a mechanism to change causing a cooling affect. It then takes a second fluid to make the process work and that is salt (usually in the form of lithium bromide). Next, the two fluids are then separated by the use of heat, and when the two are put back together and the water remixes with the salt at a slow pace, normally at a low temperature having a normal atmosphere pressure, which will cause water to vaporize at 212F within an absorber, the vaporizing water is cold enough to put off water as cold as 46F.
An explanation on description of structure, shapes, and/or diagram of system:
One could use electric chillers, however, they do cost a lot more to use, and if purchasing right out, they are going to be about twice as much. So, if one wanted to justify an absorption system that is base-loaded, it is going to take more than a reason like average electric costs. That is why the economy favors the hybrid systems, they have a combination that lets them use absorption chillers when the electricity is at its peak, however, it also lets it use electric chillers when it is not at its peak, or rather, during its base load of operation.
The savings effect on energy:
The energy savings is estimated to be upwards toward 50% more efficient as the conventional chillers.
The equipment cost, economically speaking:
The cost of the equipment that is chosen will depend on several different factors, which include: equipment, utility rate, equipment building type, climate, and scalar ratio.
Absorbers have a co-efficient in its performance (COP) that factors in at near 1.0, when compared to the engine driven compressors, which factor in at nearly 1.5 and the electric one at nearly 3.0.
How does an absorption chiller work?
There are various stages that coolant goes through during the cycle of a absorption chiller. Read more below to understand individual principles.
The effect of the single lift hot water driven absorption chillers:
Hot water driven for a single lift absorption chiller means that the water is chilled one time using a refrigerant in a double tray inside the evaporator. The refrigerant vaporizes and is absorbed, turning into a concentrated solution, usually, potassium bromide, a concentrated solution coming out of the generator. While this concentrated solution is being diluted it is absorbing the refrigerant (which is evaporated) and heat is being absorbed by the cooling water. Now, the absorber, with the diluted solution goes into the generator by heat exchanging. The water is at 950C and is heating up the diluted solution, causing the refrigerant to vaporize. After the refrigerant has vaporized it becomes condensed, returning to the refrigerant circuitry. It has regenerated the diluted absorbent and can recycle it.
The double driven hot water effect:
In an absorption chiller for a hot water driven with a double lift there is a primary cycle and the auxiliary cycle. Whereas, the chilled water is cooled down two times by the refrigerant of the double tray located in the evaporator, Once the refrigerant has vaporized it is turned into concentrated solution, which comes out of the second generator. The double tray system increases the amount of vapor that the absorber can absorb by the cooling water. Then the diluted solution that is in the absorber will flow into the first generator by the use of a lower temperature heat ex changer and a higher temperature ex changer, at 950C hot water will heat the diluted solution, and then it vaporizes the refrigerant. While the absorbent solution is an intermediate solution at the first generator, and it flows into the second generator through high-temperature heat ex changer. Now the intermediate solution that is in the second generator is being heated with use of the hot water, making more refrigerant vaporize in the second generator as well. Auxiliary diluted solution is being made as the vapor is being absorbed by the absorbent solution, which is already in the auxiliary absorber. Next, the auxiliary heat ex-changer uses the auxiliary generator to carry the auxiliary diluted solution, which is heated by use of the hot water that comes from the first generator, turning it into an auxiliary concentrated solution. In short, first the auxiliary concentrated solution gets carried to the auxiliary absorber by way of the auxiliary heat ex-changer. All vapors that are generated in the first generator, and also the auxiliary generator become condensed within the condenser, letting it flow to the evaporator. The cooling water then absorbs the condensers heat.
Direct-fired Absorption Chiller:
The direct-fired system is very similar to the hot water single lift series with one exception, and that is that it does not use hot water in order to generate an absorption solution, instead, the solution is regenerated by using a gas flame and heating it directly, this also regenerates the refrigerant.
Driven absorption chiller using the double effect of exhaust gas:
The water in the evaporator boils at a low temperature of 4.40C, this is due to the vacuum conditions inside the evaporator. The chilled water gets cooled down from the tubes of the evaporator by use of latent heat. Which in return lowers the temperature of the outlet to near 70C. The transfer of the heat gets help from the spraying of refrigerant or rather distilled water, through a refrigerant pump. Then the refrigerant or water vapors will flow to the absorber and the lithium bromide solution absorbs it. The lithium bromide now becomes a diluted solution as it reduces its amount of absorption.
The diluted solution now gets transferred by a solution pump to a generator and it is re-concentrated (re-concentrating takes two stages, which is the double-effect) by boiling the previous water absorbed, off. With the diluted solution then being pumped into a higher temperature generator and heat in order to re-concentrate into a medium concentration solution using exhaust heat coming out of the reciprocating engine’s exhaust gases.
Flowing from the high temperature generator is the intermediate solution and going into the lower temperature generator and it is heated, becoming a concentrate solution through high temperature water vapors being released out of the solution during the time in the high temperature generator.
Because of the low-temperature generator acting like a condenser in the high temperature generator, the applied heat energy of the high-temperature generator is being used in the low temperature generator as well. Compared to the single stage chiller it reduces the input by around 45%. The vapors that are released on the shell side in the low temperature generator goes into the condenser and cools, now it returns into a liquid form. The refrigerant (water) now goes back to the evaporator to begin another cycle.
The tubes of the absorber first get cooling water from the cooling tower to cool the chiller, and then circulate, removing heat caused from the vaporization.
Phoenix Chiller Repair & Maintenance
If you need to have chiller repair done on your chiller in the Phoenix area All Kote Lining, Inc. is here to help. We understand how to inspect, recondition, repair, and perform general maintenance on your chillers. This will get you the longest life, best efficiency, and get you the peace of mind you need when it comes to the chiller installed in your building or business. If you have questions or would like to schedule your chiller repair please call 480-966-4446.
Centrifugal chillers of today offer some of the highest efficiencies ever. The technology may be more advanced, and the refrigerants are newer, but some things remain the same: the systems’ need for regular maintenance.
To help today’s high-efficiency chillers maintain those efficiencies in the field, their major components — tubes, oil, compressor, condenser, refrigerant, and starting equipment, to name a few — need to be inspected and maintained regularly.
Jeff Carpenter, marketing manager, Carrier Commercial Service (Syracuse, NY), said that the top areas that affect chiller efficiency are:
- Tubes (“Make sure they are cleaned and maintained”);
- Controls, which need regular inspection and calibration;
- Refrigerant charge optimization; and
- Regular oil changes and yearly oil analysis.
The most overlooked work, he said, is “taking normal, everyday and weekly readings.” If there are no operating problems, staff might ignore this simple task. Taking regular readings, however, allows them to watch for trends, possibly catching problems before they result in equipment damage and unexpected downtime.
This article provides an overview of regular chiller maintenance pointers provided by Carpenter and Carrier technical literature.
TUBE CLEANING, WATER CIRCUITS
The condition of local water will have a lot to do with the frequency required for tube cleaning and inspection, Carpenter said. Know your water quality. The frequency with which tube cleaning winds up being performed is determined mainly due to water conditions; it may also make you decide to upgrade your chiller’s water treatment system.
“Higher-than-normal condenser pressures, together with the inability to reach full refrigeration load, usually indicate dirty tubes or air in the chiller,” states Carrier. This is where taking daily measurements and tracking them over time really pays off. “If the refrigeration log indicates a rise above normal condenser pressures, check the condenser refrigerant temperature against the leaving condenser water temperature.”
If the reading is higher than design, the condenser tubes may be dirty, or water flow rates may be incorrect.
The first step is to inspect the heat exchanger tubes and flow devices. “Inspect and clean the cooler tubes at the end of the first operating season,” the company advises. “Because these tubes have internal ridges, a rotary-type tube-cleaning system is needed to fully clean the tubes.”
An inspection of the tubes’ condition will help you determine how often future cleaning will need to be done, and whether the system needs improved water treatment in the chilled-water/brine circuit. Look for signs of corrosion and scale. The chilled-water cooler tubes are usually part of a closed circuit and less susceptible to “dirty water.” Nevertheless, they should be inspected after the first season of operation.
While you’re there, inspect the entering and leaving chilled-water temperature sensors and flow devices for corrosion or scale. Remove scale if possible, but replace the sensor or Schrader fittings if they’re corroded.
“Keeping the condenser tubes clean is essential in maintaining peak performance,” Carpenter said. “On the condenser side, at a minimum we recommend yearly tube inspections.”
Cleaning can be done as required depending on the results of the inspections. The presence of scale or other corrosion may require chemical treatment or cleaning beyond just brushing the tubes. Inspect the entering and leaving condenser water sensors and flow devices for signs of corrosion or scale. Again, replace the sensor or Schrader fitting if corroded; remove any scale.
Proper refrigerant charge in the chiller is essential for optimal performance and energy efficiency, noted Carpenter. Too much refrigerant in the unit can cause refrigerant carryover, a condition where liquid refrigerant enters the compressor and evaporates. This could lead to reduced capacity, an overloaded motor condition, excess power consumption, and possible damage to the compressor impeller.
On the other hand, Carpenter pointed out, insufficient refrigerant charge can result in the top or uppermost layers of the cooler tube bundle not being submerged in liquid refrigerant. In this situation, the “lift” on the compressor increases, resulting in higher-than-normal power consumption. In undercharged units, add refrigerant to minimize power consumption.
Carrier recommends that service contractors trim the refrigerant charge to obtain optimal chiller performance. If it becomes necessary to adjust the refrigerant charge, the company says, “Operate the chiller at design load and then add or remove refrigerant slowly, until the difference between the leaving chilled-water temperature and the cooler refrigerant temperature reaches design conditions or becomes a minimum. Do not overcharge.”
The company says that refrigerant can be added through the storage tank or directly into the chiller, per the manufacturer’s procedures. Excess refrigerant should be removed by following the manufacturer’s recommended procedures.
Often overlooked, but critical to precise operation, are control devices and the control system.
“While less obvious than the need for mechanical maintenance,” explains Carpenter, “servicing controls is just as important to the overall operation and efficiency of the chiller or chiller plant. And because the mechanical and electrical components were designed to work together, servicing your system in its entirety is the only way to ensure optimal performance and prevent serious problems.”
If the chiller is part of a central plant control or integrated into a building energy management system, Carpenter states, “It is good practice to perform regular system evaluations to ensure that performance is optimized. Trend reports can give you a complete picture of your chiller plant or entire building HVAC system. Armed with reliable information, specialists can suggest and make improvements that will enhance system operation and reduce operating costs.”
A chiller controls test is part of this regular evaluation. It “facilitates the proper operation and test of temperature sensors, pressure transducers, compressor guide vane operation, oil pump, water pumps, cooling tower control, and other on/off outputs,” says Carpenter. “Individual sensors can be calibrated on an as-needed basis or in regular intervals.”
Cleaning and examining the control contacts is another aspect of regular control service. During this part, it is less critical that proper safety procedures be followed. “Before working on any starter, shut off the chiller, open and tag all disconnects supplying power to the starter,” the company warns.
The company also warns that “The disconnect on the starter front panel does not de-energize all internal circuits. Open all internal and remote disconnects before servicing the starter. Never open isolating knife switches while equipment is operating. Electrical arcing can cause serious injury.”
First, inspect starter contact surfaces. Look for wear or pitting on mechanical-type starters. “Do not sandpaper or file silver-plated contacts,” the company states. Follow the starter manufacturer’s instructions.
Vacuum or blow off accumulated debris on the internal parts periodically with a high-velocity, low-pressure blower.
The company also notes, “Power connections on newly installed starters may relax and loosen after a month of operation. Turn the power off and retighten them.” Recheck them once a year; loose power connections can cause voltage spikes, overheating, malfunctioning, or failures, the company warns.
OIL, LUBRICATION SYSTEM
Changing the oil, of course, is critical to operation, perhaps more so than it is to efficiency; analyzing it once a year is equally important, said Carpenter. That determines the frequency of future oil changes, and may alert you to other problems in the system that can be addressed during planned maintenance rather than emergency downtime.
“Do an oil and filter change after the first year of operation,” Carpenter said, “then do a yearly oil analysis. If that’s clear, you can go do an oil change, in some cases, up to every five years.” If the oil is dirty, of course, it needs to be changed more often. Particle size can indicate if it’s from a compressor wear problem or normal wear and tear. Regardless, “Change the oil filter on a yearly basis,” the company states, “or when the chiller is opened for repairs.” The refrigerant filter-drier should be changed “once a year or more often if its condition indicates a need for more frequent replacement,” the company says.
The lubrication system should be checked every week, the company says. “Mark the oil level on the reservoir sight glass; observe the level each week while the chiller is shut down.”
If the level goes below the lower sight glass, make sure the oil reclaim system is operating properly. If more oil is required, add it through the oil drain charging valve. “A pump is required when adding oil against refrigerant pressure.” Note the amount and date that any oil is added.
Note: “Any oil that is added due to oil loss that is not related to service will eventually return to the sump,” the company points out. The oil must be removed from the sump when it reaches a high enough level.
STILL MORE TO IT
Chiller maintenance includes many other areas, such as checking for refrigerant leaks and inspecting power transducers. The point is to be regular, and to check the system’s vital signs (temperatures and pressures) daily.
Maintaining the compressor, Carpenter says, is critical to proper operation and overall equipment reliability, minimizing downtime and maximizing uptime; however, it may not be directly related to the big efficiency picture.
To inspect the bearings, the company says, a complete compressor teardown is required. Only a trained service tech should remove and examine the bearings.
Bearings and gears should be examined on a regular, scheduled basis for signs of wear. Gear inspections require a complete compressor teardown. They, too, should only be done by trained technicians. How often? That is determined by the hours of chiller operation, load conditions during operation, and the condition of the oil and lubrication system.
Excessive bearing wear can sometimes be detected through increased vibration or increased bearing temperature.
One problem is, many companies don’t have enough staff available to take daily readings. Carpenter says that’s where a service like Carrier’s National Monitoring Center can help, by monitoring remotely and alerting onsite staff to potential problems. “It speeds up the whole service process,” he says.
Companies that invest in a new, high-efficiency chiller deserve to get their money’s worth. By performing regular maintenance and taking daily readings, you can help ensure that the chiller fulfills its promise.
Phoenix Chiller Maintenance
There is a lot of work that goes into maintaining chillers and it takes training, the right tools and time to get it done right. All Kote Lining, Inc. specializes in chiller maintenance, cooling tower maintenance, and epoxy coatings that preserve metal, fiberglass, concrete, and more. Chillers need regular maintenance to get the most cooling with the least electricity. Let us help you keep your chillers running efficiently and make them last longer. Call All Kote at 480-966-4446.
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