Method and apparatus for condensing and subcooling refrigerant

A refrigeration system containing in a closed loop connection a compressor for compressing a refrigerant, a condenser for condensing the compressed refrigerant into a liquid refrigerant and discharging the liquid refrigerant through an outlet into a reservoir, said refrigeration system further comprising:

• (a) an electrically operable control valve connected between the condenser outlet and the reservoir for controlling the liquid refrigerant discharge from the condenser into the reservoir;
• (b) a temperature sensor connected near the condenser outlet for providing an electrical signal that is representative of the temperature of the liquid refrigerant near the condenser outlet;
• (c) a temperature sensor placed near the condenser for providing an electrical signal that is representative of the ambient temperature;
• and
• (d) a control circuit electrically connected to the temperature sensors and the control valve, said control circuit causing the control valve to increase the refrigerant flow therethrough when the temperature difference (".DELTA.t") between the ambient temperature and the temperature of the liquid refrigerant is less than a predetermined value to decrease the refrigerant flow therethrough when the .DELTA.t is greater than the predetermined value.

A refrigeration system containing in a closed loop connection a compressor for compressing a refrigerant, a condenser for condensing the compressed refrigerant into a liquid refrigerant and discharging the liquid refrigerant through an outlet into a reservoir, said refrigeration system further comprising:

• (a) an electrically operable control valve connected between the condenser outlet and the reservoir for controlling the liquid refrigerant discharge from the condenser into the reservoir;
• (b) a variable speed fan for providing airflow through the condenser;
• (c) a temperature sensor connected near the condenser outlet for providing an electrical signal that is representative of the temperature of the liquid refrigerant near the condenser outlet;
• (d) a temperature sensor placed near the condenser for providing an electrical signal that is representative of the ambient temperature;
• and
• (e) a control circuit connected to the control valve and the temperature sensors, said control circuit increasing the fan speed and decreasing the flow through the control valve when the temperature difference (".DELTA.t") between the ambient temperature and the temperature of the liquid refrigerant is greater than a predetermined value and decreasing the fan speed and increasing the discharge through the control valve when the .DELTA.t is less than the predetermined value.

A refrigeration system containing in a closed loop connection a compressor for compressing a refrigerant, a condenser for condensing the compressed refrigerant into a liquid refrigerant and discharging the liquid refrigerant through an outlet into a reservoir, said refrigeration system further comprising:

• (a) an electrically operable control valve connected between the condenser outlet and the reservoir for controlling the liquid refrigerant discharge from the condenser into the reservoir;
• (b) a variable speed fan for providing airflow through the condenser;
• (c) a secondary compressor connected between the reservoir and the condenser for transferring refrigerant vapors from the reservoir to the condenser;
• (d) a temperature sensor connected near the condenser outlet for providing an electrical signal that is representative of the temperature of the liquid refrigerant near the condenser outlet;
• (e) a temperature sensor placed near the condenser for providing an electrical signal that is representative of the ambient temperature;
• and
• (f) a control circuit electrically coupled to the fan, secondary compressor, control valve and temperature sensors, said control circuit controlling the fan speed and the discharge through the control valve in response to the temperature difference between the ambient temperature and the temperature of the liquid refrigerant so as to always subcool the liquid refrigerant in the condenser before discharging it into the reservoir, said control circuit also controlling the operation of the secondary compressor.

A refrigeration system containing in a closed loop connection a compressor for compressing a refrigerant, a condenser for condensing the compressed refrigerant into a liquid refrigerant and discharging the liquid refrigerant through an outlet into a reservoir, said refrigeration system further comprising:

• (a) an electrically operable control valve connected between the condenser outlet and the reservoir for controlling the liquid refrigerant discharge from the condenser into the reservoir;
• (b) a variable speed fan for providing airflow through the condenser;
• (c) a secondary compressor connected between the reservoir and the condenser for compressing refrigerant vapor from the reservoir to the condenser;
• (d) a temperature sensor connected near the condenser outlet for providing an electrical signal that is representative of the temperature of the liquid refrigerant near the condenser outlet;
• (e) a temperature sensor placed near the condenser for providing an electrical signal that is representative of the ambient temperature;
• and
• (f) a microprocessor based control circuit electrically connected to the temperature sensors, fan, control valve and secondary compressor, said control circuit controlling the discharge through the control valve as a function of the temperature difference between the ambient temperature and the temperature of the liquid refrigerant, and the fan speed to regulate the airflow around the condenser so as to enable the subcooling of the liquid refrigerant before discharging it into the reservoir.

A multi-stage refrigeration system having in a closed loop connection a plurality of commonly piped compressors for compressing refrigerant vapor and discharging it into the inlet of a condenser for condensing the refrigerant vapor into a liquid refrigerant, said condenser discharging the liquid refrigerant from an outlet into a reservoir, at least one evaporator for evaporating the liquid refrigerant, said refrigeration system further comprising:

• (a) an electrically operable control valve having an inlet and an outlet end, said inlet end of the control valve connected to the condenser outlet, said control valve controlling the discharge of the liquid refrigerant from the condenser;
• (b) a reservoir adapted to store a body of liquid refrigerant therein, connected to the outlet of the control valve through a pipe for receiving the liquid refrigerant from the condenser through the control valve, said reservoir also connected to each said evaporator for discharging the liquid refrigerant to each said evaporator;
• (c) a secondary compressor connected between the reservoir and the condenser inlet for compressing refrigerant vapor from the reservoir to the condenser inlet;
• (d) a temperature sensor connected near the condenser outlet for producing an electrical signal representative of the liquid refrigerant temperature near the condenser outlet;
• (e) a temperature sensor placed in the general vicinity of the condenser for producing an electrical signal representative of the ambient temperature;
• (f) a temperature sensor connected to the reservoir for producing an electrical signal representative of the temperature of the liquid refrigerant therein;
• (g) a level detection sensor placed in the reservoir for detecting the liquid refrigerant level in the reservoir;
• (h) a microprocess based control circuit electrically connected to each said temperature sensor, the level detection sensor, secondary compressor, control valve and fan, said control circuit causing the control valve to meter the liquid refrigerant discharge therethrough, so that during operation the control valve always discharges a minimum amount of liquid but increases the liquid refrigerant discharge when the temperature difference (".DELTA.t") between the ambient temperature and the temperature of the liquid refrigerant near the condenser outlet is less than a predetermined value and decreases the liquid refrigerant discharge when the .DELTA.t is greater than the predetermined value, said control circuit controlling the operation of the secondary compressor as a function of the temperature of the liquid refrigerant in the reservoir and the fan speed as a function of the .DELTA.t.