The use and installation of drying filters in refrigeration systems

                       The use and installation of drying filters in refrigeration systems

 Dry filters play a crucial role in refrigerant pipelines, mainly used to remove harmful substances from the system, thereby protecting important components such as expansion valves and compressors. In a refrigerant system, various harmful substances may enter the pipeline through different channels, such as the entry of water vapor and dust during production or maintenance, the influence of solid impurities and moisture during refrigerant or refrigeration oil filling, acid corrosion caused by refrigerant containing water during refrigeration system operation, and paraffin precipitation from refrigeration oil at low temperatures. The presence of these substances may seriously threaten or damage the performance of moving components in the system, as well as cylinders and refrigeration systems that require compressed gas, so timely removal is necessary.

The filtration function of the drying filter mainly relies on internal metal filter screens, polyester filter screens, glass wool, molecular sieves, activated alumina, and activated carbon materials. These materials each play different roles, such as metal filter screens and polyester filter screens mainly filtering large and small particles, glass wool and molecular sieve absorbing water and acidic substances, activated alumina absorbing acidic substances, and activated carbon used to adsorb paraffin.

According to the purpose, drying filters can be divided into two types: filtration capacity and moisture absorption capacity.

In addition, according to the installation location and purpose of use, drying filters can be divided into drying filters for liquid pipes and drying filters for suction pipes. Dry filters for liquid pipes are mainly used to protect valve components such as shut-off valves and expansion valves, avoiding blockage of throttling components such as capillaries; The dry filter used for the suction pipe mainly protects the compressor, especially suitable for large-scale systems installed on site, to avoid the problem of high compressor costs.
When installing the drying filter, it is necessary to pay attention to its position. Dry filters for liquid pipes are usually located behind the reservoir, in front of the sight glass, shut-off valve, and thermal expansion valve. There are two options for the position of the drying filter used in the suction pipe: between the gas-liquid separator and the compressor, or between the four-way valve and the gas-liquid separator. For better performance and protection, it is recommended to install it between the four-way valve and the gas-liquid separator.

For the liquid pipe drying filter in the heat pump system, special circumstances need to be noted during installation due to the need for bidirectional flow. In practical applications, there are several common installation designs, including only installing on the refrigeration cycle, using four one-way valves to set the reservoir, drying filter, and expansion valve on the common pipeline, using two one-way valves and two drying filters to work on the refrigeration and heating cycle respectively, and using bidirectional drying filters. In addition, the drying filter also serves as a cleaning system, especially after the compressor burns out.