Performance of refrigerant insufficiency and judgment of charging amount
DATE:2024-08-12 10:39:21
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Refrigerant is an indispensable part of the air conditioning system, but its usage is often difficult to control precisely. When the refrigerant is insufficient, it may lead to a decline in the performance of the air-conditioning system, a deterioration in the cooling effect, or even malfunction. Therefore, it is particularly important to accurately determine the refrigerant charge.
Performance of insufficient refrigerant
(1) The valve of the air pipe is dry, and there is no obvious coolness when touched by hand. The reason is that the refrigerant is insufficient to cause the boiling end point in the evaporator to advance, so that the valve of the refrigerant superheat increases, the temperature of the valve rises, greater than the dew point temperature of the outdoor air.
② liquid pipe valve frost. The reason is that the refrigerant is insufficient to cause a drop in pressure in the liquid pipe, the boiling point is reduced, so that the valve temperature is lower than the freezing point.
③ Open the panel of the indoor unit and remove the filter, you can find part of the evaporator dew or frost. The reason is that due to insufficient refrigerant, only part of the evaporator boiling heat absorption occurs, so that the refrigeration area is reduced accordingly;
(iv) There is no heat sensation in the exhaust air of the outdoor unit. The reason is that the condensing pressure and condensing temperature are lowered due to insufficient refrigerant, and the exhaust air temperature is also lowered.
⑤ The condensate in the receiving tray is less. The reason is that the evaporator cooling area is reduced, the condensation area is also reduced, and the amount of condensed water is reduced.
(6) The gas and liquid valves of the outdoor unit have oil stains, and there is leakage if there are oil stains. The reason is that the refrigerant and refrigeration oil have a certain degree of mutual solubility, fluorine escapes from the leak into the atmosphere, while the oil adheres to the leak around.
(7) Measure the compressor's operating current is less than the rated current. The reason is that the refrigerant is not enough to reduce the compressor workload, the current drops.
(8) The pressure measured from the outdoor unit's fluorine charging port is lower than 0.45 Mpa. The reason is that the evaporating pressure drops due to insufficient refrigerant.
Accurate judgment method of refrigerant charging
Measure the pressure. Refrigerant saturated vapor temperature and pressure is a corresponding relationship, if the known refrigerant evaporation temperature can be found corresponding to the evaporation pressure. The pressure of the gauge value by the high and low pressure gauge shows. Therefore, according to the pressure value of the pressure gauge installed on the system to determine whether the refrigerant charge is appropriate.
For example: the evaporating temperature of the air conditioner is 7.2 ℃, condensing temperature of 54.5 ℃ using R22. check the saturation temperature of R22 and saturation pressure corresponding table to determine the value of its evaporating pressure and condensing pressure value. Check the table can be seen: R22 in 7.2 ℃ when the corresponding absolute pressure value of 0.53Mpa (5.3kg/cm2) and 54.5 ℃ when the corresponding absolute pressure value of 2.11Mpa (21.1kg/cm2), the pressure will be converted to the table pressure value can be.
Use high and low pressure gauge or composite pressure gauge to test the refrigeration system in the fluorine charging, if the high and low pressure gauge value meets the above range that is, it indicates that the refrigerant charging amount is appropriate; if the high and low pressure are low, it indicates that the charging amount is not enough; if the high and low pressure are high, it indicates that the charging amount is too much. Pressure measurement method is relatively simple, often in the role of maintenance, but the disadvantage is that it is relatively coarse, accuracy is not high.
② Measure the weight. When charging Freon, prepare a small scale beforehand and put the refrigerant cylinder on the scale. Before charging, write down the weight of the cylinder and observe the pointer during the charging process. When the reduction of refrigerant in the cylinder is equal to the required charging amount, the charging can be stopped.
③ Measure the working current. Clamp ammeter to measure the compressor operating current, refrigeration, the ambient temperature of 35 ℃, the measured operating current corresponds to the nameplate current. The higher the temperature, the corresponding increase in current, the lower the temperature, the corresponding decrease in current. In the case of normal fans, two devices under the condition of heat dissipation number measured current value for comparison.
④ Measure the temperature. With a semiconductor thermometer, measuring the temperature of the evaporator inlet and outlet, liquid collector outlet and other points to determine how the refrigerant charge. In the evaporator inlet (capillary tube before 150mm) and export the temperature difference between the two points is about 7 - 8 ℃, the liquid collector outlet temperature should be higher than the outlet of the evaporator 1 - 3 ℃. If the temperature difference between the evaporator inlet and outlet is large, it indicates that the refrigerant charge is insufficient, and if the suction tube frost section is too long or there is frost phenomenon in the neighboring compressor, it indicates that the refrigerant charge is too much.
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Performance of insufficient refrigerant
(1) The valve of the air pipe is dry, and there is no obvious coolness when touched by hand. The reason is that the refrigerant is insufficient to cause the boiling end point in the evaporator to advance, so that the valve of the refrigerant superheat increases, the temperature of the valve rises, greater than the dew point temperature of the outdoor air.
② liquid pipe valve frost. The reason is that the refrigerant is insufficient to cause a drop in pressure in the liquid pipe, the boiling point is reduced, so that the valve temperature is lower than the freezing point.
③ Open the panel of the indoor unit and remove the filter, you can find part of the evaporator dew or frost. The reason is that due to insufficient refrigerant, only part of the evaporator boiling heat absorption occurs, so that the refrigeration area is reduced accordingly;
(iv) There is no heat sensation in the exhaust air of the outdoor unit. The reason is that the condensing pressure and condensing temperature are lowered due to insufficient refrigerant, and the exhaust air temperature is also lowered.
⑤ The condensate in the receiving tray is less. The reason is that the evaporator cooling area is reduced, the condensation area is also reduced, and the amount of condensed water is reduced.
(6) The gas and liquid valves of the outdoor unit have oil stains, and there is leakage if there are oil stains. The reason is that the refrigerant and refrigeration oil have a certain degree of mutual solubility, fluorine escapes from the leak into the atmosphere, while the oil adheres to the leak around.
(7) Measure the compressor's operating current is less than the rated current. The reason is that the refrigerant is not enough to reduce the compressor workload, the current drops.
(8) The pressure measured from the outdoor unit's fluorine charging port is lower than 0.45 Mpa. The reason is that the evaporating pressure drops due to insufficient refrigerant.
Accurate judgment method of refrigerant charging
Measure the pressure. Refrigerant saturated vapor temperature and pressure is a corresponding relationship, if the known refrigerant evaporation temperature can be found corresponding to the evaporation pressure. The pressure of the gauge value by the high and low pressure gauge shows. Therefore, according to the pressure value of the pressure gauge installed on the system to determine whether the refrigerant charge is appropriate.
For example: the evaporating temperature of the air conditioner is 7.2 ℃, condensing temperature of 54.5 ℃ using R22. check the saturation temperature of R22 and saturation pressure corresponding table to determine the value of its evaporating pressure and condensing pressure value. Check the table can be seen: R22 in 7.2 ℃ when the corresponding absolute pressure value of 0.53Mpa (5.3kg/cm2) and 54.5 ℃ when the corresponding absolute pressure value of 2.11Mpa (21.1kg/cm2), the pressure will be converted to the table pressure value can be.
Use high and low pressure gauge or composite pressure gauge to test the refrigeration system in the fluorine charging, if the high and low pressure gauge value meets the above range that is, it indicates that the refrigerant charging amount is appropriate; if the high and low pressure are low, it indicates that the charging amount is not enough; if the high and low pressure are high, it indicates that the charging amount is too much. Pressure measurement method is relatively simple, often in the role of maintenance, but the disadvantage is that it is relatively coarse, accuracy is not high.
② Measure the weight. When charging Freon, prepare a small scale beforehand and put the refrigerant cylinder on the scale. Before charging, write down the weight of the cylinder and observe the pointer during the charging process. When the reduction of refrigerant in the cylinder is equal to the required charging amount, the charging can be stopped.
③ Measure the working current. Clamp ammeter to measure the compressor operating current, refrigeration, the ambient temperature of 35 ℃, the measured operating current corresponds to the nameplate current. The higher the temperature, the corresponding increase in current, the lower the temperature, the corresponding decrease in current. In the case of normal fans, two devices under the condition of heat dissipation number measured current value for comparison.
④ Measure the temperature. With a semiconductor thermometer, measuring the temperature of the evaporator inlet and outlet, liquid collector outlet and other points to determine how the refrigerant charge. In the evaporator inlet (capillary tube before 150mm) and export the temperature difference between the two points is about 7 - 8 ℃, the liquid collector outlet temperature should be higher than the outlet of the evaporator 1 - 3 ℃. If the temperature difference between the evaporator inlet and outlet is large, it indicates that the refrigerant charge is insufficient, and if the suction tube frost section is too long or there is frost phenomenon in the neighboring compressor, it indicates that the refrigerant charge is too much.