The design points of capillary refrigeration system

The design points of capillary refrigeration system

1. On the high-pressure side of the refrigeration system, do not install a liquid reservoir, and try to reduce its effective volume on the premise that the condenser can contain all the refrigerant.

Because in a refrigeration system that uses capillary tubes as throttling elements, if the accumulator or condenser is too large, when the compressor stops, the refrigerant liquid will continue to flow to the evaporator. In severe cases, the liquid in the evaporator will be absorbed by the compressor. Inhaled when restarting, it is easy to produce liquid hammer and damage the compressor.

　　2. The refrigerant injected into the tank in the refrigeration system should be appropriate and accurate to match the capacity of the evaporator. Because the amount of refrigerant in the tank is too much or too little, it will affect the cooling capacity of its refrigeration system. The tank charge of the refrigerant in the general refrigeration system is determined by experiment after design calculation.

　　 3. When the capillary is selected, its inner diameter and length should have a certain ratio. If the capillary tube is too short, its flow resistance is small, the flow rate is large, and hot steam is easily mixed into the capillary tube, thereby reducing the refrigeration efficiency, and it is also easy to cause the liquid to return to the compressor and cause liquid hammer; if the capillary tube is too long, its flow resistance Large, causing the exhaust pressure to be too high, and the amount of liquid entering the evaporator is insufficient, causing the suction pressure to be too low. According to some information, under the same working condition and the same flow rate, the length of the capillary tube is approximately proportional to the 4.6th power of its inner diameter, that is, L1/L2=(D1/D2)4.6.

　　4. Appropriately increase the effective volume of the evaporator.

In a refrigeration system that uses capillary tubes as throttling elements, appropriately increasing the effective volume of the evaporator can not only prevent the liquid from returning to the compressor and cause liquid hammer, but also reduce the equilibrium pressure when the compressor is stopped, and reduce its Start load.

　　5. The refrigeration system should be kept clean and dry to avoid the entry of water or impurities.

　　Because the inner diameter of the capillary is small, the entry of water or impurities can easily cause ice blockage or dirty blockage. The components in its refrigeration system have requirements for moisture content and impurity content, and a filter drier is installed at the capillary inlet. In actual products, because of cost considerations, desiccants are rarely used in small systems, and only very cheap filters are used.