Suction stabilizer control circuit for a heat pump system

1. A suction stabilizer control circuit (SSCC) for a heat pump system, the SSCC comprising:

a thermostatic expansion valve (TXV) including

a valve body defining a valve flow path extending between a TXV inlet and TXV outlet, the valve body including a TXV head portion having a sensing connection and an equalization connection;

a throttling element extending into the valve flow path and movable to variably restrict refrigerant flow passing from the TXV inlet to the TXV outlet;

a diaphragm positioned in the TXV head portion and connected to the throttling element such that increased pressure from the sensing connection will urge the throttling element to increase refrigerant flow restriction; and

a biasing element arranged in the valve body operable to urge the throttling element to decrease refrigerant flow restriction;

TXV inlet and outlet lines extending from the TXV inlet and the TXV outlet, respectively;

a TXV bypass line having a bypass inlet and a bypass outlet connected to the TXV inlet line and TXV outlet line, respectively, such that a predetermined portion of refrigerant flow passing between the TXV inlet and outlet lines passes through the TXV bypass line;

first and second side connection lines for connecting in a liquid refrigerant transport line between heat exchangers of the heat pump system;

first side inlet and outlet lines branching from the first side connection line and connected with the TXV inlet line and TXV outlet line, respectively;

first side inlet and outlet check valves arranged in the first side inlet and outlet lines, respectively, the first side inlet check valve oriented to block flow from the TXV inlet line toward the first side connection line, the first side outlet check valve oriented to block flow from the first side connection line toward the TXV outlet line; and

second side inlet and outlet check valves arranged in the second side inlet and outlet lines, respectively, the second side inlet check valve oriented to block flow from the TXV inlet line toward the second side connection line, the second side outlet check valve oriented to block flow from the second side connection line toward the TXV outlet line;

wherein the bypass inlet connects to the TXV inlet line downstream of the first and second side inlet lines and the bypass outlet connects to the TXV outlet line upstream of the first and second side outlet lines.

2. The SSCC of claim 1 , wherein the bypass line includes a flow restricting orifice.

3. The SSCC of claim 1 , further comprising a filter dryer arranged in the TXV inlet line upstream of the bypass inlet.

4. The SSCC of claim 1 , further comprising a liquid receiver arranged in the TXV inlet line upstream of the bypass inlet.

5. The SSCC of claim 1 , further comprising:

a filter dryer arranged in the TXV inlet line upstream of the bypass inlet; and

a liquid receiver arranged in the TXV inlet line upstream of the bypass inlet.

6. The SSCC of claim 5 , wherein the filter dryer is upstream of the liquid receiver.

7. The SSCC of claim 1 , further comprising a sensing line connected to the sensing connection.

8. The SSCC of claim 7 , wherein the sensing line includes a capillary tube connected to the sensing connection and a sensing bulb at a distal end of the capillary tube, the sensing line including a sensing line refrigerant sealed therein.

9. The SSCC of claim 1 , wherein further comprising an external equalization line connected to the equalization connection.

10. The SSCC of claim 1 , further comprising:

a filter dryer arranged in the TXV inlet line upstream of the bypass inlet and downstream of the first and second side inlet lines; and

a liquid receiver arranged in the TXV inlet line upstream of the bypass inlet and downstream of the filter dryer.

11. A method of reducing condenser subcooling and evaporator superheating in a heat pump system using the SSCC of claim 1 , the method comprising:

passing refrigerant flow from a condenser outlet to the suction stabilizer control circuit (SSCC);

dividing the refrigerant flow in the SSCC into first and second portions;

directing the first portion of the refrigerant flow in the SSCC to the TXV;

variably throttling the first portion of the refrigerant flow in the TXV based on sensed superheating at an evaporator outlet;

directing the second portion of the refrigerant flow in the SSCC to the bypass line bypassing the TXV; and

combining the first and second portions of the refrigerant flow downstream of the TXV and supplying the combined refrigerant flow to an evaporator inlet.

12. The method of claim 11 , wherein directing the second portion of the refrigerant flow in the SSCC to the bypass line bypassing the TXV including passing the second portion of the refrigerant flow through a flow restricting orifice in the bypass line.

13. The method of claim 11 , further comprising passing the refrigerant flow from the condenser outlet through a filter dryer before dividing the refrigerant flow into first and second portions.

14. The method of claim 11 , further comprising passing the refrigerant flow from the condenser outlet through a liquid receiver before dividing the refrigerant flow into first and second portions.

15. The method of claim 11 , further comprising passing the refrigerant flow from the condenser outlet through a filter dryer and a liquid receiver before dividing the refrigerant flow into first and second portions.

16. The method of claim 15 , wherein the refrigerant flow is passed through the filter dryer before the liquid receiver.

17. A heat pump system comprising:

an evaporator having an evaporator inlet and outlet;

a condenser having a condenser inlet and outlet;

a refrigerant vapor transport line extending between the evaporator outlet and the condenser inlet;

a compressor arranged in the refrigerant vapor transport line between a compressor inlet and outlet and operable to compress the refrigerant vapor passing therethrough;

a refrigerant liquid transport line extending between the condenser outlet and the evaporator inlet; and

a suction stabilizer control circuit (SSCC) arranged in the refrigerant liquid transport line, the SSCC including:

a thermostatic expansion valve (TXV) including

a valve body defining a valve flow path extending between a TXV inlet and TXV outlet, the valve body including a TXV head portion having a sensing connection and an equalization connection;

a throttling element extending into the valve flow path and movable to variably restrict refrigerant flow passing from the TXV inlet to the TXV outlet;

a diaphragm positioned in the TXV head portion and connected to the throttling element such that increased pressure from the sensing connection will urge the throttling element to increase refrigerant flow restriction; and

a biasing element arranged in the valve body operable to urge the throttling element to decrease refrigerant flow restriction;

TXV inlet and outlet lines extending from the TXV inlet and the TXV outlet, respectively, and connected in the refrigerant liquid transport line;

a TXV bypass line having a bypass inlet and a bypass outlet connected to the TXV inlet line and TXV outlet line, respectively, such that a predetermined portion of refrigerant flow passing through the refrigerant liquid transport line between the TXV inlet and outlet lines passes through the TXV bypass line; and

a sensing line extending from the sensing connection to a distal end in thermal contact with the refrigerant vapor transport line proximate the evaporator outlet;

first and second side connection lines for connecting in a liquid refrigerant transport line between heat exchangers of the heat pump system;

first side inlet and outlet lines branching from the first side connection line and connected with the TXV inlet line and TXV outlet line, respectively;

first side inlet and outlet check valves arranged in the first side inlet and outlet lines, respectively, the first side inlet check valve oriented to block flow from the TXV inlet line toward the first side connection line, the first side outlet check valve oriented to block flow from the first side connection line toward the TXV outlet line; and

second side inlet and outlet check valves arranged in the second side inlet and outlet lines, respectively, the second side inlet check valve oriented to block flow from the TXV inlet line toward the second side connection line, the second side outlet check valve oriented to block flow from the second side connection line toward the TXV outlet line;

wherein the bypass inlet connects to the TXV inlet line downstream of the first and second side inlet lines and the bypass outlet connects to the TXV outlet line upstream of the first and second side outlet lines.

18. The heat pump system of claim 17 , wherein the bypass line including a flow restricting orifice.

19. The heat pump system of claim 17 , wherein the SSCC further includes:

a filter dryer arranged in the TXV inlet line upstream of the bypass inlet; and

a liquid receiver arranged in the TXV inlet line upstream of the bypass inlet.