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Central air conditioning five common failure
2012-08-14 by seoer2

1, the suction temperature is too high - mainly due to the suction superheat increases due attention to the suction temperature does not mean inspiratory pressure is high, because inhale superheated steam.
    Compressor cylinder head under normal circumstances should be half cold, half hot. If the suction temperature is too high cylinder head all the heat. If the suction temperature is higher than normal exhaust gas temperature will be elevated.
    The main cause of the high suction temperature:
    Charging amount of refrigerant in the system (1), even if the expansion valve to the maximum for the amount of fluid would not be any changes, so that the refrigerant vapor in the evaporator overheating make inspiratory temperature.
    (2) expansion valve to open through a small, resulting in a lack of system refrigerant solar power garden lights, refrigerant into the evaporator superheat to the suction temperature high.
    (3) expansion valve port filter clogging, insufficient for the amount of fluid within the evaporator, reduce the amount of liquid refrigerant within the evaporator part of superheated steam occupied, so the inspiratory temperature.
    (4) other causes suction temperature is too high, such as the poor back to the gas piping insulation or pipe is too long, can cause the suction temperature is too high.
    2, the suction temperature is too low - mainly for the fluid volume of the evaporator is too large to cause the suction superheat is low.
    (1) The refrigerant charge fluence too much, accounting for the increased partial volume leaving the condensing pressure within the condenser into the evaporator, the liquid will be increased. With liquid droplets of liquid in the evaporator can not be completely gasification, the compressor suction gas. In this way, the temperature of the gas pipeline to decline, but the evaporation temperature due to the pressure drop without change, the superheat decreases. Even if no significant improvement in off the small expansion valve.
    (2) expansion valve opening through the large. Temperature sensing element banding too loose, and back to the trachea to small contact area, or temperature sensing element is not used insulation materials wrapped its bandaged position error, resulting in temperature sensing element of the measured temperature is not accurate, near ambient temperature, so that the expansion valve action opening degree is increased, the cause for the excessive amount of fluid.
    PS: press frosting - reason: as above; two reasons: the lack of charging amount of refrigerant from the evaporator has been bound to the compressor (Note: need to verify); three reasons: due to external causes refrigerant in the evaporator device evaporation is less than even evaporation, will be severe frost, and even cause wet compression. (Such as the lack of return air central air conditioning or air conditioning box filter severely clogged chillers host press back to the trachea frosty, exhaust gas temperature is very low)
    3, the exhaust temperature is not normal - influencing factors: the adiabatic index, compression ratio, inlet temperature
    Compressor discharge temperature can be read out from the thermometer of the exhaust pipe on the road. Adiabatic index of the refrigerant compression (condensing pressure / evaporation pressure) and inspiratory temperature. Suction temperature the higher the compression ratio, exhaust gas temperature is higher, and vice versa.
    Constant inspiratory pressure, exhaust pressure, exhaust temperature rise; if the exhaust pressure is constant, the suction pressure drops, the exhaust temperature also increased. Both cases is because the compression ratio increases caused. Condensing temperature and exhaust temperature is unfavorable to the compressor is running, should be prevented. The exhaust temperature is too high lubricant thinning or even carbonization coke, so that the deterioration of the compressor lubrication conditions.
    High and low compression ratio of the exhaust gas temperature (condensing pressure / evaporation pressure) and suction temperature is proportional to. If the inspiratory overheating temperature high compression ratio, exhaust gas temperature is also high. If the suction pressure and temperature are the same, when the exhaust pressure, exhaust temperature also increased.
    Exhaust temperature for two main reasons:
    (1) a higher inlet temperature, exhaust temperature of the refrigerant vapor after compression is also higher.
    (2) condensation temperature, the condensing pressure is also high, resulting in exhaust temperature.
    (3) of the exhaust valve is crushed, high-pressure steam is repeatedly compressed and the temperature rise, the cylinder and cylinder head hot exhaust pipe on the thermometer indicated value also increased.
    The exhaust temperature factors: intermediate cooling efficiency is low, or too much influence within the scale heat exchanger in the cold, behind the level of suction temperature must be high exhaust gas temperature will rise. Valve leakage, blow, not only affects the exhaust temperature, and also make the inter-stage pressure changes, as long as the compression will be higher than normal exhaust temperature. In addition, water-cooled machines, water shortage or water shortage to make the exhaust temperature. Condensing pressure is not normal, and the exhaust pressure is reduced.
    (4) the higher discharge pressure - mainly high condensing pressure cause rather than press for their own reasons.
    The exhaust pressure is generally corresponding to the level of the condensing temperature. Under normal circumstances, the compressor discharge pressure and condensing pressure is very close.
    Condensing pressure, compressor discharge temperature also increased. Compression ratio increases, the transmission coefficient decreases, so that the cooling capacity of the compressor to reduce. Increased power consumption. If the exhaust temperature is too high, an increase of the consumption of the compressor lubricant oil thinning, the impact of lubrication; when the exhaust temperature and compressor oil flash point close to, but also make some lubricant carbonization and accumulation in the suction exhaust valve ports, valve sealing.
    Reduce the temperature of the cooling medium can be making condensing temperature decreased, the condensing pressure to fall, but this is subject to environmental constraints, it is difficult to artificial selection. Increase the cooling medium flow can reduce the condensing temperature (the use of this method). To improve the flow of cooling water or air, but not one-sided, because it will increase the power of the cooling water pump or fan motor should be comprehensive consideration.
    The high discharge pressure cause the compression work increase, the transmission coefficient is reduced, so that the cooling efficiency decreased.
    Produce the main reason of this failure:
    (1) cooling water (or air) flow is small, the temperature is high;
    (2) system with air, so that the condensation pressure;
    (3) The refrigerant charge excessive liquid occupy the effective condensation area;
    (4) condenser fell into disrepair, the heat transfer surface dirt is serious and can also lead to condensation solar power air conditioning . Scale of the presence of a condensing pressure as well.
    5, the discharge pressure is too low - mainly the refrigerant flow of refrigeration system piping is too small or even stop the cause.
    Discharge pressure is too low, although the phenomenon is manifested in the high-pressure side, but the reasons are mostly produced in the low voltage side. The reason:
    Expansion valve ice blocking or fouling of filter blockage, this will bring the suction and discharge pressure drop.