Supercooling the liquid before throttling is generally beneficial for improving the economic efficiency of Industrial Chiller refrigeration cycles, but it increases equipment investment and direct operating costs. In actual use, specific conditions should be considered and a technical and economic analysis should be conducted to determine whether liquid subcooling should be used. 1. How to determine the temperature of throttling liquid in industrial Chillers The determination of liquid subcooling temperature before throttling in industrial chillers can be based on the following experience, and we will analyze it using the commonly used Poly De refrigeration chiller refrigeration system.
In a single-stage compression system, the subcooling of the liquid before throttling is achieved in a gas-liquid heat exchanger, usually with a subcooling degree of 5 ℃; In a two-stage compression system, the liquid generally undergoes two subcooling cycles before throttling. Firstly, it is subcooled in the intermediate cooling, and then subcooled in the gas-liquid heat exchanger. The liquid temperature of the cooling coil of the intercooler is 5-7 ℃ higher than the intermediate temperature of the two-stage compression, and the liquid is further supercooled by 5 ℃ in the gas-liquid heat exchanger.
2. The function of the throttling structure of the Chiller Unit The commonly used throttling mechanisms include capillary tubes, manual throttling valves, thermal expansion valves, float control valves, etc. The capillary tubes do not have regulating functions, while the three types of throttling valves can also adjust the flow rate of refrigerant entering the evaporator of the Refrigeration Unit to adapt to changes in refrigeration load, thereby achieving the purpose of regulating and controlling cooling capacity. 1. Manual throttle valve
It is the oldest type of throttle valve. It is commonly used in ammonia refrigeration equipment to manually adjust the flow area of the valve hole to change the liquid supply to the evaporator. Usually, in the Freon refrigeration system of industrial chillers, a manual throttle valve is installed as a backup valve on the bypass pipe, which is used for automatic throttle structure maintenance.
2. Thermal expansion valve
With the change of refrigerant temperature at the outlet of the evaporator, the opening degree of the valve is automatically adjusted by the temperature sensing mechanism to control the refrigerant flow rate. The thermal expansion valve is mainly composed of a valve body, a temperature sensing bulb, and a capillary tube. It is suitable for evaporators without a free liquid surface, such as dry evaporators, snake tube evaporators, and snake tube intercoolers. It is the most commonly used throttling mechanism for chillers.
3. Floating ball control valve
It is a regulating valve that controls flow based on changes in liquid level, playing a role in throttling, reducing pressure, and controlling liquid level. It is an automatic regulating throttle valve commonly used for automatic adjustment of liquid supply to evaporators, gas-liquid separators, and intercoolers with free liquid surfaces. At present, it is mainly used in ammonia refrigeration equipment.
