Abstract A refrigerant control system, particularly useful for air conditioning apparatus, including means for operating the system with a relatively high evaporator pressure during the time the temperature within the cooled space is being reduced to its desired level. While such temperature level is being reduced, a constant pressure expansion device is adjusted to maintain the control point at a lower temperature (and pressure) to effect dehumidification. This system thus provides a higher capacity during pull-down by modifying the response level of an automatic expansion device until pull-down is achieved. Until either a reduced suction line temperature or a reduced ambient temperature (or both) is attained, the setting of the valve is higher than normal thus increasing the capacity required of the compressor for a given superheat level.
A refrigerant control system for an air conditioning system of the type including a compressor, a condenser, a constant pressure expansion device and an evaporator connected to provide a closed, vapor cycle refrigerant circuit, said control system comprising means for establishing a control signal which is indicative of the air temperature within the cooled space and means for applying said signal to said constant pressure expansion device to vary the control point thereof, and the corresponding evaporator pressure, whereby the evaporator pressure is established at a lower value when the temperature of the cooled space is below some predetermined value; means for sensing the presence of superheat of refrigerant leaving the evaporator coil; means for sensing the temperature of air circulating within the cooled space and means for deriving a signal based on the amount of superheat and said air temperature for varying the speed of said compressor.
Claim 2
Dependent Claim
148 words
A refrigerant control system for an air conditioning system of the type including a compressor, a condenser, a constant pressure expansion device and an evaporator connected to provide a closed, vapor cycle refrigerant circuit, said control system comprising means for establishing a control signal which is indicative of the air temperature within the cooled space and means for applying said signal to said constant pressure expansion device to vary the control point thereof, and the corresponding evaporator pressure, whereby the evaporator pressure is established at a lower value when the temperature of the cooled space is below some predetermined value; means for sensing the presence of superheat of refrigerant leaving the evaporator coil; means for sensing the temperature of air circulating within the cooled space and means for deriving a signal based on the amount of superheat and said air temperature for varying the speed of said compressor.