Capillary Tube
The capillary tube in an air conditioner is a key component in the refrigeration system, responsible for throttling, reducing pressure, and regulating the refrigerant flow. It throttles and reduces the pressure of high-pressure liquid refrigerant from the condenser, converting it into low-temperature, low-pressure wet vapor that enters the evaporator to absorb heat, thereby achieving the cooling effect. By varying its length or diameter, it precisely controls the refrigerant flow rate, ensuring optimal system operation.
Main Functions
Throttling and Pressure Reduction: Throttling and reducing the pressure of high-pressure, ambient-temperature refrigerant liquid from the condenser, converting it into low-temperature, low-pressure wet vapor.
Flow Control: Precisely controlling the refrigerant flow through the evaporator by varying its length and diameter.
Maintaining System Pressure Balance: Helping the high- and low-pressure sides of the system quickly balance when the compressor is shut down, reducing the load upon restart.
Optimal Cooling Performance: Each air conditioner is equipped with a capillary tube of a specific size to ensure maximum cooling capacity under the designed operating conditions.
In split-type and window air conditioning units, copper capillary tubes serve as precise metering devices. The high-pressure liquid refrigerant from the condenser enters the narrow capillary tube, where its pressure drops dramatically due to flow restriction. This pressure reduction causes the refrigerant to partially vaporize, transforming into a low-pressure mist-like mixture before entering the evaporator coil. Here, the expanded refrigerant absorbs heat from the room air, creating the cooling effect we experience. For instance, when we feel cold air blowing from an AC vent, it's the result of this capillary tube-mediated phase change process where heat is efficiently removed from the indoor environment.
In specialized medical devices like DNA analyzers and blood analyzers, stainless steel capillary tubes function as precise fluid control components. These capillary tubes, with inner diameters as small as 0.1mm, enable accurate micro-volume sample transmission through their precise inner structure. When liquid samples enter the capillary tube, surface tension and capillary action work together to maintain stable, bubble-free fluid progression. This allows instruments to precisely transport nanoliter-scale samples to reaction chambers or detection units. For example, in automated biochemical analyzers, capillary tubes ensure minute blood samples reliably reach test areas, guaranteeing accurate diagnostic results through their consistent flow control.