Placement of the thermostatic valve bulb

Placement of the thermostatic valve bulb

The bulb should be as close as possible to the outlet of the evaporator and placed in close contact with the outlet pipe. In the part of the pipe section where the temperature bulb is in contact with the pipe, the paint and rust must be thoroughly removed, and aluminum silver powder must be coated to prevent corrosion. Two thin steel leather clips are used (do not use fixing parts with large heat storage) to fix the temperature bulb Fix it firmly to ensure that the entire length of the bulb is in good contact with the wall of the outlet pipe.

　　 When the diameter of the outlet pipe is below 21 mm (7/8), the bulb is often placed on top of the horizontal pipe. When the pipe diameter is greater than 2l mm, considering that the refrigerant flows unevenly in the pipe and the temperature at the top of the pipe is higher, the bulb should be placed on the side of the pipe. The larger the pipe diameter, the lower it should be, but it should not be lower than the distance. Tube bottom 45. At the circumference of the corner, this is because when the load is low, due to the accumulation of oil at the bottom of the pipe or a small amount of liquid refrigerant flowing through, their temperature is different from the refrigerant vapor temperature (high oil temperature, low liquid refrigerant), which will cause expansion The valve does not work properly. The above regulations are not absolute, and the appropriate position should be adjusted during work. If the liquid refrigerant overflows the evaporator at low load, it can be quickly felt by the temperature bulb due to its low temperature, and the expansion valve can be closed to prevent the compressor from being hit by liquid. When the outlet pipe of the cold storage evaporator is very thick, the warm bulb can also be plugged in the pipe.

　　The bulb should be placed on a horizontal pipe section that does not accumulate as much as possible, so as to prevent the accumulation of liquid in the pipe from making the valve work abnormally. If there is no suitable horizontal pipe, it can also be placed on the vertical pipe section, but attention should be paid to avoid the liquid storage section. Because oil or liquid refrigerant may accumulate under the ascending pipe.

　　Temperature bulb should usually be placed in the cold storage, and at least away from the evaporator outlet pipe extending out of the storage wall. 5～1. O meter, in case the outside heat is transferred from the tube wall during shutdown, the temperature bulb will rise too high, which will affect the expansion width and cannot be closed. In addition to sensing the temperature of the outlet pipe section in the cold storage, the bulb should no longer be affected by the temperature of other objects. When the bulb is placed outside the cold storage, or when it is swept by circulating cold air in the cold storage, the bulb and the outlet pipe of the section should be wrapped with two layers of rubber, and the length of the bulb must exceed the two ends of the bulb by at least 30 cm. In the tea air-conditioning box, it should be noted that the warm bulb should not be placed in the place where the wind blows directly.

　　 For closed brine tanks or water cooling tanks, the temperature bulb should be placed above the highest water level; for open brine tanks, in order to prevent the influence of outside hot air, the temperature bulb must be placed below the minimum working water level. When low shut-off superheat is required, and the evaporator outlet pipe is too short or the outer diameter exceeds 54 mm, it is not suitable for the bulb to be attached to the outside of the tube, and the bulb should be directly plugged into the tube.

For some liquid-filled bulbs, attention should be paid to the placement position so that the filling agent does not flow out of the bulb due to gravity, that is, the bulb position should be lower than the capillary tube or the capillary tube should be bent upward at the outlet of the bulb A paragraph. The connection position of the outer balance pipe and the outlet of the evaporator The outer balance pipe should be connected behind the temperature bulb (compressor side), 150-200 mm away from the temperature bulb. If it is connected to a horizontal pipe section, it should come out from the top of the pipe to prevent oil accumulation in the balance pipe.

　　 If the external balance expansion valve is used only because the distributor is used, and the resistance of the evaporator itself is not large, the external balance pipe can be connected to the entrance of the evaporator. If the resistance of the evaporator exceeds the maximum allowable value, it can also be connected to the middle elbow of one of the parallel coils to prevent unequal heat load of the coils or uneven liquid supply from the distributor. If it is connected to the main outlet pipe, it will cause the expansion valve to work and oscillate.