What are the symptoms of insufficient refrigerant in refrigeration equipment? How to judge the charging amount? You will understand after reading it!
1. The performance of insufficient refrigerant
①The tracheal valve is dry, and there is no obvious cool feeling when you touch it with your hands. The reason is that insufficient refrigerant causes the boiling end point in the evaporator to advance, so that the refrigerant superheat of the valve increases, and the temperature of the valve increases, which is greater than the dew point temperature of the outdoor air.
②The liquid pipe valve is frosted. The reason is that insufficient refrigerant causes the pressure in the liquid pipe to drop and the boiling point to drop, making the valve temperature lower than the freezing point.
③Open the panel of the indoor unit and remove the filter, you can find condensation or frost on part of the evaporator. The reason is that due to the lack of refrigerant, only part of the evaporator boils and absorbs heat, which reduces the cooling area accordingly;
④ There is no heat sensation in the exhaust air of the outdoor unit. The reason is that the condensation pressure and condensation temperature are reduced due to insufficient refrigerant, and the exhaust air temperature is also reduced.
⑤ The drain hose drains intermittently or does not drain at all. The reason is that the cooling area of the evaporator 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 if there are oil stains, there will be leakage. The reason is that the refrigerant and the refrigeration oil have a certain mutual solubility, fluorine escapes from the leak point and then enters the atmosphere, and the oil adheres to the leak point.
⑦ Measure the working current of the air conditioner is less than the rated current. The reason is that the compressor work load is reduced due to insufficient refrigerant, and the current is reduced.
⑧The pressure measured from the fluorine filling port of the outdoor unit is lower than 0.45Mpa. The reason for this is a drop in evaporative pressure due to insufficient refrigerant.
2. Accurate judgment method of refrigerant charge
1. Measure the pressure. The temperature of the saturated vapor of the refrigerant has a corresponding relationship with the pressure. If the evaporating temperature of the refrigerant is known, the corresponding evaporating pressure can be found out. The gauge value of this pressure is displayed by the high and low pressure gauges. Therefore, according to the pressure value of the pressure gauge installed on the system, it can be judged whether the charging amount of the refrigerant is appropriate.
For example: the evaporating temperature of the air conditioner is 7.2°C and the condensing temperature is 54.5°C using R22. Check the corresponding table of saturation temperature and saturation pressure of R22 to determine its evaporating pressure value and condensing pressure value. It can be seen from the table that the corresponding absolute pressure value of R22 at 7.2°C is 0.53Mpa (5.3kg/cm2) and the corresponding absolute pressure value at 54.5°C is 2.11Mpa (21.1kg/cm2). Can.
Use high and low pressure pressure gauges or compound pressure gauges to test the refrigeration system in the fluorine charge. If the gauge pressure values of the high and low pressure gauges meet the above range, it indicates that the refrigerant charge is appropriate; if the high and low pressure pressures are both low, it indicates that The charging amount is not enough; if the high and low pressure pressures are both high, it indicates that the charging amount is too much. The pressure measurement method is relatively simple and often used in maintenance, but the disadvantage is that it is relatively rough and the accuracy is not high.
2. Measure the weight. When charging Freon, prepare a small scale in advance, put the refrigerant cylinder into a container, and then pour cold water below 40°C into the container (suitable for low-pressure charging refrigerant vapor for air conditioners). Note down the weight of the cylinder, warm water and container before filling, and pay attention to the pointer during the filling process. The charging can be stopped when the reduction of the refrigerant in the cylinder is equal to the required charging amount.
3. Measure the working current. Use a clamp-type ammeter to measure the working current. During refrigeration, the ambient temperature is 35°C, and the measured working current corresponds to the current on the nameplate. The higher the temperature, the higher the current, and the lower the temperature, the lower the current. When the fan is normal and the heat dissipation number of the two devices is normal, the current value is measured according to the working condition of the air conditioner for comparison.
4. Measure the temperature. Use a semiconductor thermometer to measure the temperature of the inlet and outlet of the evaporator and the outlet of the liquid collector to judge the refrigerant charge. The temperature difference between the inlet of the evaporator (150mm before the capillary) and the outlet is about 7--8°C, and the temperature at the outlet of the liquid collector should be 1-3°C higher than that at the outlet of the evaporator. If the temperature difference between the inlet and outlet of the evaporator is large, it indicates that the refrigeration capacity is insufficiently charged. If the frosting section of the suction pipe is too long or there is frosting near the compressor, it indicates that the refrigerant is overcharged.
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