Category Archives: Chillers

Industrial water chillers are used in a diverse range of applications where chilled liquid or water are circulated through processing equipment. Most frequently utilized to cool machinery and products, they are also used in die and tool cutting, chemicals, machine tool, lasers, semiconductors, injection molding and more. An industrial chiller works by moving heat from one place to a different location. Often a solution of glycol and water is used to transfer the heat back and forth from the chiller and that may necessitate a pumping and reservoir system. A sufficient cooling system is essential to your level of productivity.

Water Chiller Definition

According to Brighthub Engineering, a water chiller is a vital part of an HVAC system. It works by removing heat from the system by dehumidifying and cooling the air. The two types used in an HVAC system are the mechanical type and the absorption type. The mechanical chiller system has a condenser, evaporator, compressor as well as other controlling devices. The absorption chiller system used an absorber and generator as opposed to a compressor. You can learn more about this process here.

How Do Chillers Work?

In most cases, a pumping system is used to circulate cool water or a glycol/water solution to the process from the chiller. Cool fluid removes the warm fluid and the heat is transferred back to the chiller. Chillers contain refrigerant, a compound that differs depending on the application but they work on the same principle we have just described. This is known as the refrigeration cycle. The refrigeration cycle commences with a low-pressure liquid/gas mix entering into the evaporator.

The heat from the process water or water/glycol solution boils the refrigerant, changing it from a low-pressure liquid to low-pressure gas. The low-pressure gas enters the compressor and then becomes high-pressure gas. The high-pressure gas enters the condenser where condenser water or ambient air removes heat to cool it to a high-pressure liquid. The high-pressure liquid moves to the expansion valve, controlling how much liquid refrigerant enters the evaporator, starting the refrigeration cycle once again.

Chillers use two kinds of condensers,  water-cooled and air-cooled. In a water-cooled condenser, water from a cooling tower cools and condenses the refrigerant. An air-cooled condenser uses ambient air to cool and condense the hot refrigerant gas back down to a liquid, ultimately rejecting the heat from the chiller to the air. You can learn more about water chillers here.

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

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

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.

Reciprocating Chiller

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.

Absorption Chillers

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:

HVAC Systems

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.

Plastic Fabrication

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

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.

Printing Houses

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.

Beverage Industry

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.

Laser Applications

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.

Rubber Fabrication

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.

Phoenix Valley Chiller Maintenance

Chiller Maintenance keeps equipment in good condition, operating more efficiently, and saves money by using less energy. All Kote Lining, Inc. offers chiller maintenance and repair to the Phoenix Valley. We keep chillers and cooling towers operating at their highest possible performance. Refurbishment is one of our services which saves companies and municipalities significant operating costs in comparison to needing cooling tower or chiller replacement. Get in touch with All Kote Lining, Inc. to learn more about what we can do for your chillers and cooling towers.

Call 480-966-4446 or Contact Us

Are you looking for “Chiller System Basics” while trying to understand how chiller systems work? If so, this post should help!

How Do Chiller Systems Work

 Overview of a Chiller System

Typically, Chillers use either an absorption refrigerant, or vapor-compression cycle to cool a fluid for the transferring of heat. Both chiller types rely on three basic principles.

• 1st – When a liquid is heated to a certain degree, the liquid vaporizes into a gas, and when that gas is gets cooled, it condenses into a liquid
• 2nd – By lowering the pressure above a liquid, the lowered pressure reduces its boiling point and increasing the pressure raises it
• 3rd – Heat consistently flows from hot to cold

Cooling Cycle Basics

The basic cooling cycle is the same for both absorption chillers, and vapor-compression. Both of these systems utilize a liquid refrigerant that changes phase to a gas within an evaporator which absorbs the heat from the water to be cooled.

The refrigerant gas is then compressed into a higher pressure by a generator or compressor, converted back into a liquid by rejecting heat through a condenser and then expanded to a low- pressure mixture of vapor and liquid and that then goes back into the evaporator section.  The cycle then starts the process all over.

Vapor Compressor Chiller

A vapor-compression chiller is made up of four primary components of the vapor-compression refrigeration cycle. These include a metering device, a condenser, a compressor, and an evaporator.

Vapor-compression chillers commonly utilize CFC or HCFC refrigerants to achieve a refrigeration effect. Compressors are the driving force behind a vapor-compression chiller, and acts as a sort of pump for the refrigerant.

Compressed refrigerant gas is sent from the compressor into a condenser unit that renounces the heat energy from the refrigerant to cooling air or water outside of the system.

The transfer of heat allows the refrigerant gas to condense into a liquid which is then sent to a metering device.

The metering device hinders the flow of liquid refrigerant which causes it to drop in pressure. Due to adiabatic flash evaporation, the drop in pressure causes the heated refrigerant liquid to change phase from liquid to gas and in doing so absorbs heat from the water to be.

The metering device is in a position so that the expanding refrigerant gas is contained within the evaporator, transmitting the heat energy from the water to be cooled into the refrigerant gas. The warm refrigerant gas is then sent back to the compressor to restart the cycle, and the newly chilled water in the separate loop can now be used for cooling.

Absorption Chiller

An absorption chiller or absorption refrigerator uses a heat source to drive the refrigeration cycle in place of a mechanical compressor. Absorption chillers use two fluids which include a refrigerant, usually water and an absorbent; commonly a lithium bromide solution or ammonia.

These liquids are then separated and recombined in the absorption cycle where, due to the low pressure conditions, the water can more easily change phase than it normally would. The high affinity of the two liquids encourages easy absorption.

The cycle starts with a mixture of liquid refrigerant water and absorbent, that is heated at a greater pressure to boil the water out of solution. After that, the refrigerant water vapor is sent past a condenser coil where heat is lowered and is condensed into a high pressure liquid. The liquid refrigerant water is then sent to the lower pressure evaporator where through adiabatic flash evaporation returns into a gas, absorbing the heat from the water to be chilled. The condensed liquid absorbent from the generator is sent back to be recombined with the low-pressure refrigerant vapors returning from the evaporator restarting the cycle over again.

Cooling Towers

The heat energy absorbed by the chiller is required to be rejected out of the system and into the atmosphere. Evaporative heat rejection devices called cooling towers are commonly used to lower the water temperature in larger chiller installations.

Phoenix Chiller Maintenance & Repair

If you have a industrial or commercial building that uses chillers All Kote Lining, Inc. can help maintain and repair your chiller.  Regular chiller maintenance, chiller tube coating, and other quality services help chillers be more efficient, use less energy, and ultimately last longer. Give us a call to find out what we can do for you and your chillers in the Phoenix Valley.

Call Today – 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.

Outline:

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.

Remarks:

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.