Selection and installation of the expansion valve for ultra low temperature recirculating chillers
: the selection of expansion valve plays an important role in the performance of the ultra low temperature recirculating chiller refrigeration system. The correct choice of expansion valve will maximize the use of the evaporator and make the evaporator always be matched to the heat load.
First, the selection of thermal expansion valve.
In the ultra low temperature recirculating chiller refrigeration system, the selection and installation of the expansion valve is very important. Only the correct selection and installation can ensure the normal operation of the unit. Therefore, when selecting the expansion valve, we can use the appropriate size of the thermal expansion valve according to the size of the evaporator load and the evaporating temperature. The capacity of the commonly used expansion valve is about 20% larger than the evaporator heat load. For small chiller refrigeration systems, gas-filled thermal expansion valves are generally used, and medium-sized ultra-low temperature circulating chiller refrigeration systems mostly use adsorption-filled or mixed-filled expansion valves.
Second, the expansion valve installation.
1. The chiller expansion valve is installed in front of the evaporator and is usually installed in a vertical position. Considering the ease of installation and maintenance, the cooling loss is small and should be as close as possible to the inlet of the evaporator.
2. The working condition of the expansion valve for the ultra low temperature recirculating chiller has a direct relationship with the installation position of the temperature sensing package. Because the expansion valve completely adjusts the opening size of the expansion valve by the temperature change of the temperature sensing package. The temperature sensor package is installed on the pipe at the outlet of the chiller evaporator. As the evaporator outlet pipe grows, its superheat gradually increases. Therefore, the position of the expansion valve temperature sensing package is directly related to the amount of fluid supplied from the expansion valve.