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Working Principle of Water Chiller


Chiller is a kind of water cooling equipment, chiller is a kind of cooling water equipment that can provide constant temperature, constant flow and constant pressure. The working principle of the chiller is to inject a certain amount of water into the machine tank first, through the chiller refrigeration system to cool the water, and then the pump will send the low-temperature cooling water into the equipment to be cooled, the chiller chilled water will take away the heat and then the temperature rises back to the tank, to achieve the role of cooling. Cooling water temperature can be automatically adjusted according to the requirements, long-term use can save water. Therefore, the chiller is a standard energy-saving equipment.   

The chiller cooling principle: The chiller system operates through three interrelated systems: the refrigerant closed circulation system, the water circulation system, and the electrical automatic control system.   

The liquid refrigerant in the evaporator absorbs heat from the water and starts to evaporate, eventually a certain temperature difference is formed between the refrigerant and the water, and the liquid refrigerant is completely evaporated into a gaseous state and then absorbed and compressed by the compressor (pressure and temperature increase). The gaseous refrigerant absorbs heat through the condenser (air/water-cooled), condenses into liquid, and after throttling through the thermal expansion valve (or capillary tube), becomes low temperature and low pressure refrigerant into the evaporator to complete the refrigerant cycle.   

The basic components of the chiller refrigeration system: Compressor: The compressor is the core component of the entire refrigeration system, and is also the source of power for refrigerant compression. Its role is to convert the input electrical energy into mechanical energy, the refrigerant compression.    Condenser: In the refrigeration process, the condenser plays the role of outputting heat energy and enabling the refrigerant to condense. After the high temperature and high pressure superheated vapor from the refrigeration compressor enters the condenser, all the heat absorbed in the working process, including the heat absorbed from the evaporator and the refrigeration compressor and in the pipeline, is transferred to the surrounding medium (water or air); the refrigerant high pressure superheated vapor condenses into liquid again. (According to the different cooling media and cooling methods, condensers can be divided into three categories: water-cooled condensers, air-cooled condensers, evaporative condensers.) So the naming of the chiller is based on the condenser is water-cooled or air-cooled to name   

Liquid reservoir: The liquid reservoir is installed after the condenser and is directly connected to the discharge pipe of the condenser. The refrigerant liquid from the condenser should flow into the reservoir unimpeded, so that the cooling area of the condenser can be fully utilized. On the other hand, when the heat load of the evaporator changes, the amount of refrigerant liquid needed also changes, then, the reservoir will play the role of transferring and storing refrigerant. For small chiller refrigeration system, often not installed with a reservoir, but the use of condenser to transfer and storage of refrigerant.   

Filter drier: In the chiller refrigeration cycle must prevent the entry of moisture and dirt (oil, iron, copper), the source of moisture is mainly the newly added refrigerant and lubricating oil contains a trace of water, or due to the maintenance system when the air into the moisture. If the moisture in the system is not eliminated, when the refrigerant passes through the throttle valve (thermal expansion valve or capillary tube), sometimes the moisture will solidify into ice because of the pressure and temperature drop, making the channel blocked and affecting the normal operation of the refrigeration unit. Therefore, the filter drier must be installed in the chiller refrigeration system.   

Thermal expansion valve: thermal expansion valve in the chiller refrigeration system is both a flow control valve and a throttle valve in the refrigeration equipment, it is installed in the refrigeration equipment between the filter drier and evaporator, and its temperature-sensitive package is wrapped in the outlet of the evaporator. Its main role is to make the high pressure room temperature refrigerant liquid in the flow through the thermal expansion valve throttle down, into low temperature low pressure refrigerant wet vapor (mostly liquid, a small part is steam) into the evaporator, in the evaporator vaporization heat absorption, and to achieve the purpose of refrigeration cooling.   

Evaporator: evaporator is the heat exchange equipment that relies on the evaporation (actually boiling) of refrigerant liquid to absorb the heat of the cooled medium. Its function in the refrigeration system is to absorb heat (or output cold). In order to ensure that the evaporation process can be stable and lasting, the evaporated gas must be constantly pumped away with the refrigeration compressor to maintain a certain evaporation pressure.   Refrigerant (commonly known as refrigerant): Most industrial chillers used in modern industry use R22, R410A, R134A or R407C, etc., as refrigerant. Refrigerant is the flowing work substance in the refrigeration system, its main role is to carry heat and achieve heat absorption and exotherm when the state changes.