Refrigeration system controlled by refrigerant quality within evaporator
원문보기
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
F25B-041/04
F25B-041/00
출원번호
US-0312706
(2011-12-06)
등록번호
US-8646286
(2014-02-11)
발명자
/ 주소
Scherer, John
Tator, Ralph
출원인 / 주소
PDX Technologies LLC
대리인 / 주소
Sheldon Mak & Anderson PC
인용정보
피인용 횟수 :
10인용 특허 :
9
초록▼
A method of controlling a refrigeration system having a refrigerant disposed within a fluid-tight circulation loop with a compressor, a condenser and an evaporator, wherein the method includes the steps of (a) compressing refrigerant in a gaseous state within the compressor and cooling the refrigera
A method of controlling a refrigeration system having a refrigerant disposed within a fluid-tight circulation loop with a compressor, a condenser and an evaporator, wherein the method includes the steps of (a) compressing refrigerant in a gaseous state within the compressor and cooling the refrigerant within the condenser to yield refrigerant in the liquefied state; (b) flowing refrigerant from the condenser into the evaporator, wherein the refrigerant partially exists in a two-phase state; (c) flowing refrigerant from the evaporator to the compressor; (d) repeating steps (a)-(c); (e) detecting the condition of the refrigerant with a sensor disposed within the evaporator upstream of the outlet opening; and (f) controlling the flow of refrigerant to the evaporator in step (b) based upon the detected condition.
대표청구항▼
1. A method of controlling a refrigeration system, wherein the refrigeration system comprises a refrigerant disposed within a fluid-tight circulation loop including a compressor, a condenser and an evaporator comprising one or more evaporator tubes, the refrigerant being capable of existing in a liq
1. A method of controlling a refrigeration system, wherein the refrigeration system comprises a refrigerant disposed within a fluid-tight circulation loop including a compressor, a condenser and an evaporator comprising one or more evaporator tubes, the refrigerant being capable of existing in a liquified state, a gaseous state and a two-phase state comprising both refrigerant in the liquified state and refrigerant in the gaseous state, the evaporator having an upstream section with an inlet opening and a downstream section with an outlet opening, the method comprising: (a) compressing refrigerant in a gaseous state within the compressor and cooling the refrigerant within the condenser to yield refrigerant in a liquified state;(b) flowing the refrigerant in a liquified state into the evaporator;(c) reducing the pressure of the refrigerant within the evaporator to yield refrigerant in a two-phase state;(d) reducing the pressure of the refrigerant in a two-phase state within the evaporator to yield a refrigerant in a gaseous state;(e) flowing refrigerant in a gaseous state from the evaporator to the compressor;(f) repeating steps (a)-(e);(g) measuring the ratio of the measured volume of vapor to the volume of liquid in refrigerant in a two-phase state with a refrigerant condition sensor disposed within the evaporator upstream of the outlet opening and downstream of the inlet opening; and(h) controlling the flow rate of refrigerant to the evaporator in step (b) based upon the measured ratio from step (g) to a flow rate required to wet at least most of the entire surface of the evaporator tubes. 2. The method of claim 1 wherein the controlling of the flow of refrigerant in a liquid state to the evaporator in step (h) is based upon the measured quality of the refrigerant within the evaporator. 3. The method of claim 1 wherein the measured condition of the refrigerant within the evaporator upstream of the outlet opening in step (g) is the measured condition of the refrigerant at an intermediate point within the evaporator. 4. The method of claim 1 wherein the measured condition of the refrigerant within the evaporator upstream of the outlet opening in the step (g) is the calculated condition of the refrigerant at an interpolation of the measured conditions of the refrigerant at a pair of intermediate points within the evaporator. 5. The method of claim 1 wherein refrigerant in a liquified state from step (a) is precooled prior to being flowed into the evaporator in step (b). 6. The method of claim 5 wherein refrigerant in a liquified state from step (a) is precooled to 0° F. to 60° F. of its boiling point at the pressure of the refrigerant at the inlet opening of the evaporator. 7. The method of claim 5 wherein refrigerant in a liquified state from step (a) is precooled to 0° F. to 30° F. of its boiling point at the pressure of the refrigerant at the inlet opening of the evaporator. 8. The method of claim 5 wherein refrigerant in a liquified state from step (a) is precooled to 0° F. to 5° F. of its boiling point at the pressure of the refrigerant at the inlet opening of the evaporator. 9. The method of claim 5 wherein the evaporator comprises tubing, an inlet, and an outlet, and the method comprises the additional steps of (i) removing refrigerant from the evaporator tubing between the inlet and the outlet, (ii) precooling refrigerant from step (a) with the removed refrigerant, and (iii) introducing the removed refrigerant back into the evaporator tubing at a location downstream from the location from which the refrigerant was removed. 10. The method of claim 1 wherein the measured condition of the refrigerant in step (g) is determined from refrigerant drawn from the evaporator, and wherein refrigerant in a liquified state from step (a) is precooled by thermal contact with refrigerant flowing within the evaporator. 11. The method of claim 1 wherein the upstream section of the evaporator comprises one or more lengths of tubing each having an upstream first cross-sectional area and a second downstream cross-sectional area, the second cross-sectional area being greater than the first cross-sectional area, the expansion in cross-sectional area between the first circular cross-sectional area and the second circular cross-sectional area being smooth and continuous. 12. The method of claim 1 wherein the upstream section of the evaporator comprises a plurality of upstream circuits and the downstream section comprises a plurality of downstream circuits, and wherein a plurality of the upstream circuits are connected to a plurality of the downstream circuits by a midsection header. 13. The method of claim 12 wherein the control of flow of refrigerant in a liquid state to the evaporator is based upon the measured condition of the refrigerant within the midsection header. 14. A refrigeration system comprising: (a) a fluid tight circulation loop including a compressor, a condenser and an evaporator, the circulating loop being configured to continuously circulate a refrigerant which is capable of existing in a liquified state, a gaseous state and a two-phase state comprising both refrigerant in the liquified state and refrigerant in the gaseous state, the evaporator having one or more evaporator tubes, an upstream section with an inlet opening and a downstream section with an outlet opening, the circulation loop being further configured to (i) compress refrigerant in a gaseous state within the compressor and cool the refrigerant in the condenser to yield refrigerant in a liquified state; (ii) flow the refrigerant in a liquified state into the evaporator; (iii) reduce the pressure of the refrigerant within the evaporator to yield refrigerant in a two-phase state; (iv) reduce the pressure of the refrigerant in a two-phase state within the evaporator to yield a refrigerant in a gaseous state; (v) flow refrigerant in a gaseous state from the evaporator to the compressor; and (vi) repeat steps (i)-(v);(b) a refrigerant condition sensor disposed within the evaporator upstream of the outlet opening and downstream of the inlet opening to sense the ratio of the measured volume of vapor to the volume of liquid in refrigerant in a two-phase state within the evaporator; and(c) a controller for controlling the flow of refrigerant in a liquid state to the evaporator based upon the ratio of the measured volume of vapor to the volume of liquid in refrigerant in a two-phase state, so that the flow rate of refrigerant to the evaporator can be controlled to a flow rate required to wet at least most of the entire surface of the evaporator tubes. 15. The refrigeration system of claim 14 wherein the measured condition of the refrigerant employed by the controller to control the flow of refrigerant to the evaporator is the measured quality of the refrigerant at an intermediate point within the evaporator. 16. The refrigeration system of claim 14 wherein the condition of the refrigerant employed by the controller to control the flow of refrigerant to the evaporator is the calculated condition of refrigerant at an interpolation of the measured conditions of the refrigerant at a pair of intermediate points within the evaporator upstream of the outlet opening. 17. The refrigeration system of claim 14 further comprising an internal precooler for precooling refrigerant flowed into the evaporator. 18. The refrigeration system of claim 17 wherein the precooler is capable of cooling refrigerant to within 0° F. to 30° F. of its boiling point at the pressure of the refrigerant at the inlet opening of the evaporator. 19. The refrigeration system of claim 17 wherein the controller is adapted to determine the condition of the refrigerant drawn from the evaporator, and wherein refrigerant in a liquified state from step (a) is precooled by thermal contact with refrigerant flowing within the evaporator. 20. The refrigeration system of claim 14 wherein the upstream section of the evaporator comprises one or more lengths of tubing each having a first cross-sectional area, and wherein the downstream section comprises one or more lengths of tubing, each having a second cross-sectional area which is greater than the first cross-sectional area, the expansion in cross-sectional area between the first circular cross-sectional area and the second circular cross-sectional area being smooth and continuous. 21. The refrigeration system of claim 14 wherein the upstream section of the evaporator comprises a plurality of upstream circuits and the downstream section comprises a plurality of downstream circuits, and wherein a plurality of the upstream circuits are connected to a plurality of the downstream circuits by a midsection header. 22. The refrigeration system of claim 21 wherein the control of flow of refrigerant in a liquid state to the evaporator is based upon the measured condition of the refrigerant measured within the midsection header. 23. The refrigeration system of claim 14 comprising no equipment for removing liquid refrigerant from the circulation loop flowing between the evaporator and the compressor. 24. The system of claim 14 comprising (i) evaporator tubing as part of the evaporator, (ii) an evaporator header for receiving refrigerant, the evaporator header being between the inlet opening and the outlet opening, (iii) a precooler for precooling refrigerant flowed into the evaporator with refrigerant in the evaporator header, and (iv) a connection for passing the refrigerant used for precooling back into the tubing. 25. A method of controlling a refrigeration system, wherein the refrigeration system comprises a refrigerant disposed within a fluid-tight circulation loop including a compressor, a condenser and an evaporator comprising one or more evaporator tubes, the refrigerant being capable of existing in a liquefied state, a gaseous state and a two-phase state comprising both refrigerant in the liquefied state and refrigerant in the gaseous state, the evaporator having an upstream section with an inlet opening and a downstream section with an outlet opening, the method comprising the steps of: (a) compressing refrigerant in a gaseous state within the compressor and cooling the refrigerant within the condenser to yield refrigerant in the liquefied state;(b) flowing refrigerant from the condenser into the evaporator, wherein the refrigerant partially exists in a two-phase state;(c) flowing refrigerant from the evaporator to the compressor;(d) repeating steps (a)-(c);(e) measuring the ratio of the measured volume of vapor to the volume of liquid in refrigerant in a two-phase state with a refrigerant condition sensor disposed within the evaporator upstream of the outlet opening and downstream of the inlet opening; and(f) controlling the flow rate of refrigerant to the evaporator in step (b) based upon the measured ratio from step (e) to a flow rate required to wet at least most of the entire surface of the evaporator tubes;wherein refrigerant in a liquified state from step (a) is precooled prior to being flowed into the evaporator in step (b); andwherein a plurality of the upstream circuits are connected to a plurality of the downstream circuits by a midsection header. 26. The method of claim 25 wherein the evaporator comprises tubing, an inlet, and an outlet, and the method comprises the additional steps of (i) removing refrigerant from the evaporator coil at a location between the inlet and the outlet, (ii) precooling refrigerant flowing from the condenser into the evaporator with the removed refrigerant, and (iii) introducing the removed refrigerant back into the evaporator tubing at a location downstream from the location from which the refrigerant was removed. 27. A method for cooling a refrigerant comprising the steps of: (a) compressing refrigerant in a gaseous state within a compressor and cooling the refrigerant within a condenser to yield refrigerant in a liquefied state;(b) flowing refrigerant from the condenser into an evaporator comprising one or more evaporator tubes;(c) flowing refrigerant from the evaporator to the compressor;(d) repeating steps (a)-(c);(e) measuring the ratio of the measured volume of vapor to the volume of liquid in refrigerant in a two-phase state with a refrigerant condition sensor disposed within the evaporator upstream of the outlet opening; and(f) controlling the flow rate of refrigerant to the evaporator in step (b) based upon the measured ratio from step (e) to a flow rate required to wet at least most of the entire surface of the evaporator tubes. 28. The method of claim 27 wherein the measured condition of the refrigerant within the evaporator upstream of the outlet opening in the step (e) is the calculated condition of the refrigerant at an interpolation of the measured conditions of the refrigerant at a pair of intermediate points within the evaporator. 29. The method of claim 27 wherein the upstream section of the evaporator comprises one or more lengths of tubing each having an upstream first cross-sectional area and a second downstream cross-sectional area, the second cross-sectional area being greater than the first cross-sectional area, the expansion in cross-sectional area between the first circular cross-sectional area and the second circular cross-sectional area being smooth and continuous. 30. The method of claim 27 wherein the evaporator comprises tubing, an inlet, and an outlet, and the method comprises the additional steps of (i) removing refrigerant from the evaporator tubing at a location between the inlet and the outlet, (ii) precooling refrigerant flowing from the condenser into the evaporator with the removed refrigerant, and (iii) introducing the removed refrigerant back into the evaporator tubing at a location downstream from the location from which the refrigerant was removed.
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