received by the International Bureau on 7 October2014(07.10.2014)

1. A control system for a refrigeration circuit comprising a low side line having an evaporator and a high side line having a compressor and the low side line extending a low side lino distance from an upstream control valve to a downstream compressor inlet;

the low aide line distance comprising an evaporator line having an evaporator line distance extending downstream through the evaporator from an evaporator inlet to an evaporator outlet and an evaporator outlet line distance extending from the evaporator outlet to a downstream compressor inlet;

the low aide line having a transfer coefficient proportional to the low side line distance, the low side line heat transfer coefficient comprising an evaporator line heat transfer coefficient corresponding to the evaporator line distance and an evaporator outlet line heat transfer capacity corresponding to the evaporator outlet line distance;

a source providing heat energy to the low side line;

A working fluid rofrigorant in the refrigeration circuit and extending through the low side circuit, the refrigerant flowing downstream through the low side line from the upstream control valve to the downstream compressor inlet, the refrigerant flowing at a flow rate metered by the control valve, the refrigerant having an expected energy value corresponding to the fluid distance traveled downstream from the control valve and the flow rate end the refrigerant having an actual energy value corresponding to a working fluid liquid to vapor refrigerant ratio;

a first void fraction sensor located in the evaporator line located in the low side circuit line a first sensor distance downstream from the control valve;

a second working fluid refrigerant sensor located in the low side circuit line a second sensor distance downstream from the control valve and downstream from the first working fluid refrigerant sensor, the second sensor distance greater than the first sensor distance;

the first void fraction sensor detecting the working fluid liquid to vapor refrigerant ratio at the first sensor distance and the second refrigerant sensor detecting a second refrigerant actual energy value at the second sensor distance; a programmable controller in communication with the first and second refrigerant sensors and the control valve, said controller receiving the working fluid liquid to vapor refrigerant ratio from the first void fraction sensor and the second refrigerant actual energy values from the second refrigerant sensor, the controller programed with a first goal set point value corresponding to the expected energy value or refrigerant at the first eensor distance and a second goal set point value corresponding to the expected energy value of refrigerant at the second sensor distance,

wherein if refrigerant actual energy value at the second sensor distance is different from the second sennor set point, the controller actuates the control valve to increase or the flow of working fluid refrigerant. through the low side line and changes the first goal set point value to a corrective set-point value.

2. The control system of claim 1 wherein the first sensor distance comprises a first percentage distance of the evaporator line distance and the first goal set point value corresponds to the expected energy value of refrigerant at a first percentage distance of the evaporator line distance.

3. The control system of claim 2 wherein the second working fluid refrigerant sensor is a second void fraction sensor located in the evaporator line, the second sensor distance comprises a second percentage distance of the evaporator line distance, the second percentage distance of the evaporator line distance greater than the first percentage distance of the evaporator line distance, the second refrigerant actual energy value corresponding to the working fluid liquid to vapor refrigerant ratio at the second sensor distance and the second goal set point value corresponds to the expected energy value of refrigerant at the second percentage distance of the evaporator line distance.

4. The control system of claim 2 wherein the second working fluid refrigerant sensor is a first superheat sensor located in the evaporator outlet line.

5. The control system of claim 1 comprising a third working fluid refrigerant sensor located in the low side circuit line a third sensor distance downstream from the control valve, the third refrigerant sensor detecting a third refrigerant actual energy value at the third sensor distance, the programmable controller in communication with the third refrigerant sensor; the controller receiving, third refrigerant actual energy values from the third refrigerant sensor, the controller programed with a third goal set point value corresponding bo the expected energy value of refrigerant at the third sensor distance wherein if refrigerant actual energy value at the third sensor distance is different from the third sensor set point, the controller actuates tho control valve to increase or decrease the flow of working fluid refrigerant through the low side line.

6. The control system of claim 5 wherein the third working fluid refrigerant sensor is located upstream of the second working fluid refrigerant sensor and wherein if refrigerant actual energy value at the second sensor distance is different from the second sensor set point, the controller changes the third goal set point value to a third corrective set-point value.

7. ft. control system for a refrigeration circuit, the refrigeration circuit comprising a low side line having an evaporator and a high side line having a compressor, the low side line extending a line distance from an upstream control valve to a downstream compressor inlet, the low side line distance comprising an evaporator line having an evaporator line distance extending, downstream through the evaporator from an evaporator inlet to an evaporator outlet and on evaporator outlet lino distance extending from the evaporator outlet to a downstream compressor inlet;

the low side line having a heat transfer coefficient proportional bo the low side line distance, the low side line heat transfer coefficient comprising an evaporator line heat transfer coefficient corresponding to the evaporator line distance and an evaporator outlet line heat transfer capacity corresponding to the evaporator outlet line distance;

an ambient source providing heat energy to the low side line; a working fluid refrigerant in the refrigeration circuit and extending through the low side circuit, the refrigerant flowing downstream through the low side line from the upstream control valve to the downstream compressor inlet, the refrigerant flowing at a flow rate metered by the control valve, the refrigerant having an expected energy value corresponding to the fluid distance traveled from the control valve and the flow rate and the refrigerant having an actual energy value;

a void fraction sensor located in the evaporator line a sensor distance downstream from the control valve, the sensor distance comprising a percentage distance of the evaporator line distance;

the void fraction eeneor detooting a working fluid liquid to vapor refrigerant ratio at the sensor distance;

a programmable controller in communication with the refrigerant sensor and the control valve, said controller receiving the working fluid liquid to vapor refrigerant ratio from the void fraction sensor, the controller programed with a senaor set point corresponding to the expected energy value of refrigerant at the sensor distance wherein if the refrigerant actual energy value corresponding to the working fluid liquid to vapor refrigerant ratio at the sensor distance is different from the sensor set point, the controller actuates the control valve to increase or decrease the flow of working fluid refrigerant through the low side line.

8. The control system of claim 7 wherein the void fraction sensor is located in the evaporator line at an evaporator line distance of about 50% of the total evaporator line distance. 9· The control system of claim 7 wherein the void fraction sensor is located in the evaporator line at an evaporator line distance of about 80% of the total evaporator line distance.

10. The control system of claim 7 comprising a second working fluid refrigerant sensor in communication with the programmable controller, the second refrigerant sensor located in the low side circuit line a second sensor distance downstream from the control valve, the second sensor distance comprising a percentage distance of the evaporator line distance, the second refrigerant sensor detecting a second refrigerant actual energy value at the second sensor distance, the controller programed with a second sensor set point corresponding to the expected, energy value of refrigerant at the second sensor distance wherein if the refrigerant actual energy value at the second sensor distance is different from the second sensor set point, the controller actuates the control valve to increase or decrease the flow of working fluid refrigerant through the low aide line.

11. The control system of claim 7 wherein the second working fluid refrigerant sensor is a void fraction sensor and the actual energy value corresponds to the working fluid liquid to vapor refrigerant ratio at the second sensor distance.

12. The control system of claim 7 wherein the second working fluid refrigerant sensor is a superheat sensor and the actual energy value corresponds to the degree of superheat in refrigerant present within the refrigerant at tho second sensor distance.

13. The control system of claim 7 wherein the refrigerant actual energy value at the sensor distance is different from the sensor set point/ and the controller adjusts the second sensor act point.

14. A method of regulating a refrigeration circuit comprising the steps of:

A. Providing a refrigeration circuit comprising a low side line low side line distance extending from an upstream control valve to a downstream compressor inlet, the low side line comprising an evaporator, an evaporator line and an evaporator outlet line, the low side line further comprising a heat transfer coefficient proportional to the low side line distance, the low side line heat transfer coefficient comprising an evaporator line heat transfer coefficient corresponding to a evaporator line distance and an evaporator outlet line heat transfer capacity corresponding to a evaporator outlet line distance;

B. Providing a heat energy source to the low side line;

C. Providing a working fluid refrigerant to the refrigeration circuit to the low side line through the uuntrol valve;

D. Flowing refrigerant downstream through the evaporator line an evaporator line distance;

E. Flowing heat energy from the heat energy source to refrigerant in the evaporator line at an amount corresponding to an evaporator line heat transfer coefficient and the evaporator line dietnnea;

F. Detecting refrigerant the working fluid liquid to vapor refrigerant ratio at the evaporator line distance;

G. Calculating the actual energy value at the evaporator line distance from the working fluid liquid to vapor refrigerant ratio at the evaporator line distance;

H. Comparing the actual energy value at the evaporator line distance to an expected energy value set-point of refrigerant at the evaporator line distance; and H. Actuating the control valve if the actual energy value does not match the expected energy value set-point.

15. The method of claim 14 further Comprising the steps of:

I. Flowing refrigerant an additional downstream line distance through the low side line;

J. Flowing heat energy from the heat energy source to refrigerant in the evaporator outlet line at an amount corresponding to a low side heat transfer coefficient and the additional downstream line distance;

K. Detecting refrigerant actual energy value at the additional downstream line distanca;

L. Comparing the actual energy value at the evaporator outlet line distance to an expected energy value set-point of refrigerant at the additional downstream line distance; and M. Actuating the control valve if the actual energy value at the additional downstream line distance does not match the expected energy value set-point additional downstream line distance.

16. The method of claim 14 further comprising the steps of:

I. Flowing refrigerant downstream through the evaporator outlet line an evaporator outlet line distance;

J. Flowing heat energy from the heat energy source to refrigerant in the evaporator outlet line at an amount corresponding to an evaporator outlet line heat transfer coefficient and the evaporator outlet line distance;

K. Detecting refrigerant actual energy value at the evaporator outlet line distance;

L. Comparing the actual energy value at the evaporator outlet line distance to an expected energy value set-point of refrigerant at the evaporator outlet line distance; and

M. Actuating the control valve if the actual energy value does not match the expected energy value set-point.

17. The method of claim 16 wherein step H comprises changing the expected energy value set-point of refrigerant at the evaporator outlet line distance.