Refrigeration equipment structures vary widely, and user requirements differ for different equipment, leading to variations in capillary tube structural designs.
1. Single Capillary Tube
For typical refrigerators or single-cooling air conditioners, a single capillary tube is sufficient for throttling. Whether this capillary tube is coiled or placed in a long strip depends on the refrigeration equipment's structure. In household refrigerators, the condenser and evaporator are relatively close, so it's usually coiled. In some commercial air-cooled freezers, the condenser and evaporator are further apart, so it's typically placed in a strip embedded in the foam layer.
2. Single Capillary Tube with One-Way Valve
This type is generally used in heat pumps. Because the capillary tube lengths required for cooling and heating are different, two sets of capillary tubes are used for cooling and heating. When a capillary tube is not in use, it is short-circuited through a one-way valve. This structure requires two one-way valves, but the design is simple and they do not interfere with each other, making it particularly suitable for split-type air conditioners with long connecting pipes.
3. Dual Capillary Tube Combination
For heat pump type household air conditioners, sometimes the capillary tube cannot be placed in the indoor unit (to avoid excessive noise). One capillary tube is used for cooling, and another capillary tube is added for heating. This second capillary tube is short-circuited using a one-way valve during the cooling cycle.
4. Multiple Capillary Tubes
When the evaporator is relatively large, if the flow path is too long, the design needs to split the circuit. Capillary tubes can also be used for throttling and distribution. In this case, the requirements for the distributor are not as strict as for dedicated distributor pipes, because the capillary tube itself can adjust due to its throttling effect, avoiding uneven distribution problems. This structure is generally only used in single-cooling systems.
