Home > News > News Center > Analysis of common faults and phenomena of air cooled chiller units
Oct.2020 20
Views: 1033
Analysis of common faults and phenomena of air cooled chiller units
Details
(1) Exhaust pressure too high If the exhaust pressure of the system is too high, the compressor will run overload for a long time, which will greatly shorten the service life of the compressor, increase the wear of the compressor, and even cause the compressor to burn down in serious cases. High exhaust pressure is often caused by the following reasons: A. the heat exchanger is dirty or partially blocked Paper, leaves and other debris deposited on the condenser fins (heating is the shell and tube evaporator dirty) will make it seriously affected, because these impurities are the condensing unit can not carry out normal heat exchange work. Treatment method: clean the heat exchanger. B. air or other non condensable gases are mixed into the refrigeration circuit If air or other non condensable gases enter the condenser, the exhaust pressure will increase abnormally, higher than the pressure corresponding to the condensing temperature of refrigerant steam. At the same time, the low pressure and the pointer on the high pressure gauge were shaking. Treatment method: discharge refrigerant, vacuum and refill refrigerant. C. insufficient condensing air volume, insufficient water flow of shell and tube heat exchanger or insufficient rotating speed of condensing fan Similar to the case of condenser blockage: insufficient heat transfer between refrigerant and cooling medium. Even if the condenser is not blocked, there will be other reasons to reduce the cooling medium. For example, there are obstacles at the outlet of the condenser, but there is no wind guide cover. The air outlet is blocked and the wind cannot blow out. D. the ambient temperature of condensation is too high If the air temperature around the condensing unit begins to rise, the discharge pressure of the condensing unit will also increase accordingly. Treatment method: equip the outdoor unit with a sunshade to prevent it from direct sunlight. At the same time, the unit should be installed in an open and ventilated place. E. the air condensation cycle is shortened If the position of the condensing unit (outdoor) is close to the wall or obstacles, the high-temperature air discharged from the condenser will be re pumped in by it, which is equivalent to the high ambient temperature, which will increase the high-pressure value of the refrigerant and make the high-pressure switch act to brake the compressor. Treatment: the unit is installed in an open and ventilated place. If it is difficult to do so, a wind guide hood should be added on the exhaust outlet to prevent short circuit of condensed air flow. (2) Suction pressure too low A during refrigeration Insufficient air flow through the evaporator coil is the most common cause of low suction pressure. If the air flowing through the evaporator coil is too slow, the normal heat transfer between the refrigerant and the air will be correspondingly weakened, that is, when the heat that the refrigerant obtains from the air for evaporation is less, the temperature of the refrigerant will be reduced, and the corresponding suction pressure will be reduced. This situation is often caused by the installation of the air duct is too long, or the air duct is too small, or the air flow is not smooth. Treatment: clean the air filter and blow the evaporator. B refrigerant flow is blocked In order to make the refrigerant effectively evaporate through the cooling coil matching the compressor capacity, and absorb the appropriate amount of heat from the air, the evaporator needs a sufficient amount of refrigerant. Any obstruction to the flow of refrigerant means a reduction in the ability of the cooling coil to absorb heat from the air. This resistance of the refrigerant in the passage is easy to find according to its position, because there is a significant decrease in temperature at this point of obstruction. There are mainly the following situations: Expansion valve blocked There are mechanical problems in the expansion valve: sometimes it is basically closed or completely closed by dirt and water vapor freezing and adhesion, which reduces the refrigerant flow of the evaporator. If the expansion valve is completely blocked, the low refrigerant pressure will be reduced to the extent that the switch acts and stops the compressor. If the low-pressure switch is not installed, the compressor will continue to run. As a result, the compressor motor is no longer cooled by refrigerant steam, which makes the exhaust temperature increase abnormally. Therefore, the thermal protector acts to stop the compressor. If there is no low-pressure switch, the outlet of expansion valve will seep or frost, and the cooling coil and suction pipe will become hot; Treatment: replace the expansion valve, if it is found that it is dirty and blocked, it is also necessary to clean and blow the system; Dryer or filter blocked The drying filter on the liquid path is sometimes blocked by dust and dirt. If such a fault occurs, the temperature of the refrigerant flowing out of the drying or filter will be lower than that of the flowing in. If the blockage is serious, it will lead to water seepage or frosting at the outlet. Local blockage of valve and blockage of liquid path If the valve in the liquid circuit is not fully open, the temperature of the liquid in the liquid circuit will decrease after passing through the valve, which is lower than the temperature when it is in the condenser. If there is an obstacle in the liquid path, the temperature of the liquid path behind the obstacle will be lower than that before the obstacle. In extreme cases, water seepage or frost will occur in the pipeline behind the obstacle, while the cooling coil and suction line will be warm. (3) Refrigerant "short circuit" The short circuit of refrigerant in refrigeration cycle can be detected by the warming of suction pipe and high suction pressure. If the refrigerant short circuit is quite obvious, the refrigerant vapor can not be effectively condensed through the condenser and effectively absorb heat from the air. The refrigerant short circuit of the modular unit is mainly caused by the reverse cross flow of one-way valve around the compressor pipeline.
