What Does A Chiller Do?
Let’s take a detailed look at what chillers do and how they operate.
Water Chiller Guide
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.
Chillers use one of two methods, an absorption refrigerant cycle or a vapor-compression for cooling fluids for the heat transfer. Each type depends on three basic principles to work.
- Liquid gets heated and vaporized, creating a gas. As gas is cooled, it is condensed to a liquid.
- By decreasing pressure of a liquid lowers the boiling point, while increasing the pressure raises the boiling point.
- Heat will flow hot to cold, always.
Basic Cooling Cycle
Both absorption chillers and vapor-compression have the same basic cooling cycle’s. They use liquid refrigerant which changes stages to gas inside an evaporator that absorbs the heat from water, which then gets cooled.
Refrigerant gas gets compressed with higher amounts of pressure by a generator or compressor, then converts back to its liquid state as heat is rejected through the condenser, expanding a lower pressure combination of liquid and vapors which then ends up back in an evaporator section. This starts the cycles over.
Vapor Compressor Chiller
Consisting of four main components, a vapor compression chiller uses a vapor compression refrigeration cycle. These components include the evaporator, compressor, metering device, and condenser.
Usually, vapor compression chillers will use either CFC or HCFC refrigerants to get the refrigeration effect. The force that drives a vapor compression chiller is the compressors, which acts like a refrigerant pump.
The compressor sends compressed refrigerant gases to the condenser which then rejects any heat energy to the air outside or cooling water of the system.
The heat transfer provides the needed refrigerant gas for condensing a liquid that gets sent to the metering device.
The liquid refrigerant flow is restricted by the metering device, which results in a pressure drop. This drop causes a change in warm refrigerant liquid so that it creates a gas which absorbs heat out of the water that is then cooled because of adiabatic flash evaporation.
Metering devices are placed so expanding refrigerant gases are contained inside the evaporator, which transfers heat energy between the water that needs to be cooled and into a refrigerant gas. The warmed refrigerant gas then goes back into the compressor to begin the whole cycle over, with the recently chilled water being in a separate loop and used for the cooling process.
Absorption Chiller
A heat source is used by an absorption chiller to drive refrigeration cycles in the place of mechanical compressors. Two fluids are used for the absorption chillers, including a refrigerant that is often water, and an absorbent which is often ammonia or a lithium bromide mixture.
The absorption cycle separates and recombines these liquids, where the lower pressures allow the water to change phases easier than usual, with a high affinity of the liquids promoting easier absorption.
This cycle starts with a combination of liquid absorbent and refrigerant water which gets heated at higher pressures, boiling water from the solution. Then, the vapor from the refrigerant water gets sent to the condenser coil, heat is rejected and condensed to a high pressure liquid. This liquid then gets put through the lower pressure evaporator using the method of adiabatic flash evaporation to convert it back into a gas, which absorbs heat from the water which is to be cooled. The liquid absorbent is now concentrated in the generator, and gets recombined with a lower pressure refrigerant vapor that is returned by the evaporator, and the cycle starts over.
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