METHOD AND APPARATUS FOR COOLING

• US 20080245083A1
• Filed: 06/11/2008
• Published: 10/09/2008
• Est. Priority Date: 08/15/2006
• Status: Active Grant

• Current Assignee: American Power Conversion Corporation (Schneider Electric SE)
• Original Assignee: American Power Conversion Corporation (Schneider Electric SE)
• Inventors: Bean, John H., Tutunoglu, Ozan
• Granted Patent: US 8,322,155 B2
• Time in Patent Office: Days
• US Class Current: 62/115
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/52 Indication arrangements, e.g. displays
• CPC Class Codes: F24F 11/63 Electronic processing
• CPC Class Codes: F25B 1/00 Compression machines, plants or systems with non-reversible cycle F25B3/00, F25B5/00, F25B6/00, F25B7/00, F25B9/00 take precedence
• CPC Class Codes: F25B 2400/0403 for the condenser
• CPC Class Codes: F25B 2500/18 Optimization, e.g. high integration of refrigeration components
• CPC Class Codes: F25B 2500/19 Calculation of parameters
• CPC Class Codes: F25B 2600/111 of condenser fans
• CPC Class Codes: F25B 2600/112 of evaporator fans
• CPC Class Codes: F25B 2600/2501 Bypass valves
• CPC Class Codes: F25B 2700/13 Mass flow of refrigerants
• CPC Class Codes: F25B 2700/1931 Discharge pressures
• CPC Class Codes: F25B 2700/1933 Suction pressures
• CPC Class Codes: F25B 49/005 of safety devices F25B49/02 and F25B49/04 take precedence
• CPC Class Codes: F25B 49/02 for compression type machines, plants or systems
• CPC Class Codes: H05K 7/20827 within rooms for removing heat from cabinets, e.g. air conditioning devices
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

A method of calculating net sensible cooling capacity of a cooling unit includes measuring a discharge pressure from of fluid from a compressor and a suction pressure from an evaporator, calculating a condensing temperature of fluid flowing from the compressor and an evaporating temperature of fluid flowing from the evaporator, calculating a mass flow rate of fluid flowing from the compressor, calculating enthalpy of fluid flowing from the compressor, of fluid flowing from the thermal expansion valve, and of fluid flowing from the evaporator, calculating a mass flow rate of fluid flowing through the hot gas bypass valve, and calculating net sensible cooling capacity. Embodiments of cooling units and other methods are further disclosed.

Claims

1. A method of calculating net sensible cooling capacity of a cooling unit of the type comprising a compressor, a condenser in fluid communication with the compressor, a thermal expansion valve in fluid communication with the condenser, an evaporator in fluid communication with the thermal expansion valve, and a hot gas bypass valve in fluid communication with the compressor and the evaporator, the method comprising:

measuring a discharge pressure from of fluid from the compressor and a suction pressure from the evaporator;

calculating a condensing temperature of fluid flowing from the compressor and an evaporating temperature of fluid flowing from the evaporator;

calculating a mass flow rate of fluid flowing from the compressor;

calculating enthalpy of fluid flowing from the compressor, of fluid flowing from the thermal expansion valve, and of fluid flowing from the evaporator;

calculating a mass flow rate of fluid flowing through the hot gas bypass valve; and

calculating net sensible cooling capacity.

2. The method of claim 1, wherein calculating net sensible cooling capacity is determined by employing the following equation:

P_c=(Q_total−

Q_{comp loss}−

1052.6*C*0.2928104−

P_f)/1000

where

P_c—

net sensible cooling capacity (kW);

Q_total—

total cooling capacity (W);

Q_{comp loss}—

compressor heat loss (W);

C—

condensate production rate (lbs/hr);

1052.6—

amount of energy required to condense one pound of water;

0.2928104—

converts BTU/hour to Watts; and

1000—

converts Watts to Kilowatts.

3. The method of claim 2, wherein total cooling capacity is determined by employing the following equations:

Q_total=M*(h_{suction gas}−

h_{mix evaporator inlet}); and

h_{mix evaporator inlet}=(M_bypass*h_{hot gas}+(M−

M_bypass)*h_liquid)/M,

where

Q_total—

total cooling capacity (W);

M—

refrigerant mass flow rate calculated via using ARI-540 mass flow rate coefficients (kg/sec);

h_{suction gas}—

enthalpy of the gas refrigerant at evaporator coil inlet (W/kg);

h_{mix evaporator inlet}—

enthalpy of the mixed refrigerant at evaporator coil inlet (W/kg);

M_bypass—

refrigerant mass flow rate bypassed through bypass valve (kg/sec);

h_{hot gas}—

enthalpy of the hot gas refrigerant at compressor outlet (W/kg); and

h_liquid—

enthalpy of the liquid refrigerant at expansion valve inlet (W/kg).

4. The method of claim 1, wherein calculating net sensible cooling comprising calculating total cooling.

5. The method of claim 1, further comprising measuring a parameter of the bypass valve, and manipulating the operation of the bypass valve when the parameter is above a predetermined threshold.

6. The method of claim 5, wherein the parameter is a pressure differential.

7. The method of claim 6, wherein determining the pressure differential is achieved by measuring the pressure of fluid flowing through a discharge pressure sensor and measuring the pressure of fluid flowing from through a suction pressure sensor.

8. A cooling unit comprising:

a housing;

a compressor coupled to the housing;

a first heat exchanger coupled to the housing;

a second heat exchanger coupled to the housing;

a thermal expansion valve configured to control the delivery of fluid to the second heat exchanger;

a conduit system in fluid communication with the compressor, the first heat exchanger, the second heat exchanger, the thermal expansion valve, and the compressor;

a bypass valve provided in the conduit system, the bypass valve being configured to divert a portion of coolant from the compressor to the second heat exchanger; and

a controller to control the operation of the thermal expansion valve and the bypass valve, the controller being configured to calculate net sensible cooling capacity of the cooling unit based on parameters taken from the cooling unit.

9. The cooling unit of claim 8, further comprising at least one first air moving device coupled to the housing and configured to direct air over the first heat exchanger.

10. The cooling unit of claim 9, further comprising at least one second air moving device coupled to the housing and configured to direct air over the second heat exchanger, the second air moving device comprising at least one variable speed fan.

11. The cooling unit of claim 8, wherein the first heat exchanger comprises a condenser unit, and wherein the second heat exchanger comprises an evaporator unit.

12. A cooling unit comprising:

a compressor;

a first heat exchanger in fluid communication with the compressor;

a second heat exchanger in fluid communication with the compressor and the first heat exchanger;

a thermal expansion valve configured to control the delivery of fluid to the second heat exchanger;

a bypass valve in fluid communication with the compressor and the first heat exchanger, the bypass valve being configured to divert a portion of coolant from the compressor to the second heat exchanger; and

a controller to control the operation of the thermal expansion valve and the bypass valve, the controller being configured to calculate net sensible cooling capacity of the cooling unit based on parameters taken from the cooling unit.

13. The cooling unit of claim 12, further comprising at least one first air moving device coupled to the housing and configured to direct air over the first heat exchanger.

14. The cooling unit of claim 13, further comprising at least one second air moving device coupled to the housing and configured to direct air over the second heat exchanger, the second air moving device comprising at least one variable speed fan.

15. The cooling unit of claim 12, wherein the first heat exchanger comprises a condenser unit, and wherein the second heat exchanger comprises an evaporator unit.

16. A cooling unit comprising:

a compressor;

a condenser in fluid communication with the compressor;

a thermal expansion valve in fluid communication with the condenser;

an evaporator in fluid communication with the thermal expansion valve;

a hot gas bypass valve in fluid communication with the compressor and the evaporator; and

a controller coupled to a plurality of temperature and pressure sensing devices disposed between the compressor and the condenser and the evaporator and the compressor, the controller being configured to

calculate a condensing temperature of fluid flowing from the compressor and an evaporating temperature of fluid flowing from the evaporator,

calculate a mass flow rate of fluid flowing from the compressor,

calculate enthalpy of fluid flowing from the compressor, of fluid flowing from the thermal expansion valve, and of fluid flowing from the evaporator,

calculate a mass flow rate of fluid flowing through the hot gas bypass valve; and

calculate net sensible cooling capacity.

17. The cooling unit of claim 16, wherein the processor is further configured to process a measurement of a discharge pressure from of fluid from the compressor and a suction pressure from the evaporator.

18. The cooling unit of claim 16, wherein the mass flow rate of fluid flowing through the hot gas bypass valve is calculated by measuring the pressure differential across the hot gas bypass valve and employing a formula created for refrigeration systems having hot gas bypass valves.

19. The cooling unit of claim 18, wherein determining the pressure differential is achieved by measuring the pressure of fluid flowing through a discharge pressure sensor and measuring the pressure of fluid flowing from through a suction pressure sensor.

20. A computer readable medium having stored thereon sequences of instruction including instructions that will cause a processor to:

process a measurement of a discharge pressure from of fluid from the compressor and a suction pressure from the evaporator;

calculate a condensing temperature of fluid flowing from the compressor and an evaporating temperature of fluid flowing from the evaporator;

calculate a mass flow rate of fluid flowing from the compressor;

calculate enthalpy of fluid flowing from the compressor, of fluid flowing from the thermal expansion valve, and of fluid flowing from the evaporator;

calculate a mass flow rate of fluid flowing through the hot gas bypass valve; and

calculate net sensible cooling capacity.

21. The computer readable medium of claim 20, wherein the mass flow rate of fluid flowing through the hot gas bypass valve is calculated by measuring the pressure differential across the hot gas bypass valve and employing a formula created for refrigeration systems having hot gas bypass valves.

22. The cooling unit of claim 21, wherein determining the pressure differential is achieved by measuring the pressure of fluid flowing through a discharge pressure sensor and measuring the pressure of fluid flowing from through a suction pressure sensor.