| 摘要 |
An air conditioning system has a compressor for compressing a liquid refrigerant to form a high pressure vapor which is fed to a condenser for cooling the vapor so that it returns to liquid state and fed to an evaporator. In the evaporator, the liquid is transformed back to a vapor which absorbs heat from the surroundings and provides cooled air. A receiver stores extra refrigerant which is used at low ambient temperatures to flood the condenser to facilitate operation at ambient temperatures which are low compared to the ambient temperatures at which the capacity of the system is rated. A shutoff valve is employed to isolate the high and low pressure elements of t he system from each other to enable servicing or pumping down of the system. An accumulator prevents liquid from entering the compressor and a head pressure control maintains a minimum pressure on the high pressure side of the system to assure that the temperature and pressure of the liquid refrigerant remains high enough when the ambient temperature surrounding the condenser is low.
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