Small chiller: a water cooling device. Small chiller is a cooling water device that can provide constant temperature, constant flow and constant pressure. The working principle of small chiller is to first inject a certain amount of water into the water tank inside the machine, cool the water through the small chiller refrigeration system, and then use the water pump to send the low-temperature cooling water to the equipment to be cooled. The small chiller takes away the heat and the temperature rises before returning to the water tank to achieve the cooling effect. The cooling water temperature can be automatically adjusted according to requirements, and long-term use can save water. Therefore, small chiller is a standard energy-saving equipment.

(I) Cooling principle of small chiller:

The operation of the small chiller system is through three interrelated systems: refrigerant circulation system, water circulation system, and electrical automatic control system.

(II) Small chiller refrigerant circulation system:

The liquid refrigerant in the evaporator absorbs the heat from the water and begins to evaporate. Finally, a certain temperature difference is formed between the refrigerant and the water. The liquid refrigerant also completely evaporates and becomes gaseous, which is then sucked in and compressed by the compressor (pressure and temperature increase). The gaseous refrigerant absorbs heat through the condenser (air cooling/water cooling), condenses into liquid, and becomes low-temperature and low-pressure refrigerant after throttling through the thermal expansion valve (or capillary tube) and enters the evaporator to complete the refrigerant circulation process.

Basic components of the refrigeration system of a small chiller:

1. Condenser: In the refrigeration process, the condenser plays the role of outputting heat energy and condensing the refrigerant. After the high-pressure superheated steam discharged from the refrigeration compressor enters the condenser, all the heat absorbed during 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) and taken away; the high-pressure superheated steam of the refrigerant is condensed 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, and evaporative condensers.)

2. Compressor: The compressor is the core component of the entire refrigeration system and the source of power for refrigerant compression. Its function is to convert the input electrical energy into mechanical energy and compress the refrigerant.

3. Thermal expansion valve: The thermal expansion valve is both a flow regulating valve and a throttle valve in the refrigeration equipment in a small chiller refrigeration system. It is installed between the filter dryer and the evaporator in the refrigeration equipment, and its temperature sensing package is wrapped at the outlet of the evaporator. Its main function is to throttle and reduce the pressure of the high-pressure and normal-temperature refrigerant liquid when it flows through the thermal expansion valve, and turn it into low-temperature and low-pressure refrigerant wet vapor (mostly liquid, a small part is steam) to enter the evaporator, vaporize and absorb heat in the evaporator, and achieve the purpose of cooling and cooling.

4. Evaporator: The evaporator is a heat exchange device that relies on the evaporation (actually boiling) of the refrigerant liquid to absorb the heat of the cooled medium. Its function in the refrigeration system is to absorb heat (or output cooling capacity). In order to ensure that the evaporation process can be carried out stably and permanently, the evaporated gas must be continuously extracted by the refrigeration compressor to maintain a certain evaporation pressure.

5. Liquid receiver: The liquid receiver is installed after the condenser and is directly connected to the drain pipe of the condenser. The refrigerant liquid of the condenser should flow into the liquid receiver 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 required amount of refrigerant liquid also changes accordingly. At that time, the liquid receiver plays the role of adjusting and storing refrigerant. For small chiller refrigeration system, liquid receiver is often not installed, but the condenser is used to adjust and store refrigerant.

6. Dry filter: In the refrigeration cycle of small chillers, it is necessary to prevent the entry of moisture and dirt (oil, iron filings, copper filings), etc. The source of moisture is mainly the trace moisture contained in the newly added refrigerant and lubricating oil, or the moisture brought by the air entering the system during the maintenance. If the water in the system is not completely removed, when the refrigerant passes through the throttle valve (thermal expansion valve or capillary tube), the water may freeze into ice due to the drop in pressure and temperature, blocking the passage and affecting the normal operation of the refrigeration device. Therefore, a drying filter must be installed in the refrigeration system of a small chiller.

7. Refrigerant: Most small industrial chillers used in modern industry use R22 or R12 as refrigerant. Refrigerant is the flowing medium in the refrigeration system. Its main function is to carry heat and absorb and release heat when the state changes.