The function and setting of the oil trap in the refrigeration system

The function and setting of the oil trap in the refrigeration system

In the Fuli Subaru refrigeration and air-conditioning system, when the main engine is higher than the end (evaporator), there is a riser pipe between the evaporator and the main suction pipe, because the refrigerating oil will not evaporate in the evaporator and accumulate at the bottom. , When there is a lot of refrigerating oil accumulated at the bottom of the evaporator, the suction pipe will be blocked. If there is an oil return bend at the bottom of the evaporator, there will not be too much oil in the elbow. As long as the elbow is about to be blocked, the pressure difference between the two ends is sufficient to "pump" the limited refrigerant oil in the elbow. , Until the top horizontal suction pipe, and then sucked back by the compressor down the slope. If you are worried that the riser pipe is too long to pump the oil to the top, you should consider setting up an oil return bend on the riser suction pipe every certain height difference (for example, 8 meters), so that the refrigerated oil will gradually return to the main engine. .

When the main engine is lower than the end (evaporator) and the height difference is large, although the refrigerating oil can be automatically returned to the main engine along the slope without the oil return curve, at this time, it is worried that the oil return will cause the main engine "liquid strike" due to too much oil return. The main suction pipe is provided with an oil return bend every certain height difference distance (for example, 8 meters), so that the refrigerated oil gradually returns to the main engine in sections.

During low-load operation, refrigerant oil accumulates in the oil return elbow. Due to the limitation of the flow rate, the effect of driving the oil return only by "as long as the elbow is about to be blocked, the pressure difference between the two ends" is very small. Increase the output capacity of the compressor to increase the suction speed. If the suction speed can be increased to a larger value, then there is no need to increase the return curve. The actual situation is that, in view of the influence of the internal heat transfer effect on the compressor under small load Excessive increase in output can easily cause system control problems. Low pressure is too low and suction has no superheat. This means that the increase in suction speed is limited. When there is a large height difference, the return curve must be used to return step by step. oil!

　　 When the air pipe in the riser exceeds 10 meters, install an oil trap every 10 meters. Two "U"-shaped bends or one "back" bend are used to make the oil trap, and the height is generally 3-5 times the pipe diameter.