Refrigeration – Disparate apparatus utilized as heat source or absorber – With vapor compression system
Reexamination Certificate
1999-09-15
2001-04-17
Doerrler, William (Department: 3744)
Refrigeration
Disparate apparatus utilized as heat source or absorber
With vapor compression system
C062S175000, C062S238600
Reexamination Certificate
active
06216481
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a refrigeration system with floating head pressure and with heat reclaim.
BACKGROUND OF THE INVENTION
An ordinary refrigeration system for supermarket application uses multiples evaporators to refrigerate or to maintain in frozen conditions different perishable food products. The refrigerant vapors from the evaporators are fed to the refrigeration compressors, several in number, where through a mechanical compression their pressure and temperature are increased. The high pressure hot refrigerant vapors are fed to an outdoor air cooled condenser, where the latent heat of the refrigerant vapors is absorbed by the outdoor air and as a result the refrigerant vapors are liquified. This liquid is fed through expansion valves, thus reducing its temperature and pressure, to the evaporators, where the liquified refrigerant evaporates absorbing heat from the surrounding food products.
The pressure and the temperature of the refrigerant vapors condensing in the air cooled condenser are subject of the outdoor air temperature. During the cold period of the year, even if there is a possibility to reduce the condensing pressure, a high condensing pressure is maintained artificially in order to provide a sufficient pressure differential for the proper operation of the expansion valves; another reason for maintaining a high condensing pressure during the cold periods of the year is the use of heat reclaim coils to recuperate the heat of condensation and use it for comfort heating of the building. In order to obtain an efficient heat transfer in the heat reclaim coil, a substantial difference between the indoor air temperature and the condensing temperature is required which can be provided only by increasing the condensing pressure.
It is well known that the refrigeration compressor energy consumption efficiency is function of the ratio between the condensing pressure and the evaporating pressure. By lowering the condensing pressure, the refrigerant capacity of the compressor is increased and its power consumption decreased.
A new technology exists today (liquid delivery system) allowing the refrigeration system to work with floating condensing pressure depending on the outdoor air temperature. This is achieved by installing a centrifugal pump on the line of liquid refrigerant after the condenser, thus providing the necessary pressure differential for the proper operation of the expansion valves using a very small amount of energy. The condensing temperature could be reduced to 60° F. depending on the outdoor air temperature.
The above mentioned technology produces energy savings up to 35% of the total energy cost but creates difficulties in the field of heat reclaim especially when a recuperation of the total condensing heat is required because the air to be heated is warmer then the refrigerant to be cooled. When a heat reclaim is required the condensing pressure has to be raised artificially in order to achieve proper heat transfer, thus losing the benefits of the liquid delivery system.
OBJECTS OF THE INVENTION
It is therefore the purpose of this invention to provide a method and a system facilitating the extraction of the total condensing heat of a refrigeration system having a floating condensing pressure without the necessity to increase the condensing pressure during the heat reclaim periods.
A feature of the invention is to provide a method and a system of heat reclaim adaptable to the existing refrigeration systems Another feature of the invention is the usage of the heat reclaim system for air conditioning and subcooling purposes.
SUMMARY OF THE INVENTION
The present invention is directed to a refrigeration system with heat reclaim and with floating condensing pressure, said system comprising at least one first compressor for compressing low pressure refrigerant gas from at least one first evaporator to elevate said gas pressure to an operating high pressure level, a first outdoor air cool condenser connected to said first compressor for cooling said high pressure refrigerant gas to produce a cooled operating liquid refrigerant for feeding said first evaporator through a first expansion valve, a first heat exchanger one side of which is series connected between said first compressor and said first condenser and the other side of which forms a second evaporator of a heat pump system which further includes at least one second compressor for compressing low pressure refrigerant gas from said second evaporator, at least one heat reclaim condenser connected to the high pressure side of said second compressor and to said second evaporator through a second expansion valve.
Preferably, the system further includes a valve for selectively cutting the connection between said first compressor and said first condenser and also a pressure regulating valve to maintain at a constant value the suction pressure of said second compressor.
Preferably, the system further includes a second outdoor air cooled condenser connected between said second compressor and a third expansion valve in a circuit bypassing said heat reclaim condenser, a receiver connected to the inlet of said second and third expansion valves and to the outlets of said heat reclaim condenser and of said second condenser, and remotely operated valves for selectively connecting said second condenser and said heat reclaim condenser to said receiver.
Preferably, there are several parallel circuits of first compressors, first evaporators and first expansion valves, series connected to a single first condenser and to said one side of a single first heat exchanger.
The invention is also directed to the combination of the above defined refrigeration system with a sub- cooling system which comprises a second heat exchanger one side of which is connected to the source of cooled liquid refrigerant of said refrigeration system and the other side of which forms a sub-cooling evaporator, a third compressor for compressing low pressure refrigerant gas from said sub-cooling evaporator to a high pressure level, a third outdoor air cooled condenser connected to said high pressure side of said third compressor and to said sub-cooling evaporator through a fourth expansion valve, and valve means to selectively connect said third compressor in the circuit of said heat pump system in parallel with said second compressor and disconnect said third compressor from said circuit.
The invention is also directed to the combination of the above defined refrigeration system with an air conditioning system which comprises an air conditioning evaporator connected to said receiver through a third expansion valve and through the suction side of said second compressor.
The invention is further directed to the combination of the above defined refrigeration, sub-cooling and air conditioning systems.
REFERENCES:
patent: 4193781 (1980-03-01), Vogel et al.
patent: 4502292 (1985-03-01), Ares et al.
patent: 4535603 (1985-08-01), Willitts et al.
patent: 4711094 (1987-12-01), Ares et al.
patent: 4803848 (1989-02-01), LaBrecque
patent: 5673567 (1997-10-01), Dubé
patent: 5689966 (1997-11-01), Zess et al.
patent: 5826433 (1998-10-01), Dubé
Doerrler William
Jiang Chen-Wen
LandOfFree
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