Refrigeration – Reversible – i.e. – heat pump – With atmospheric condensate removal or prevention
Reexamination Certificate
1999-07-21
2001-08-21
Doerrler, William (Department: 3744)
Refrigeration
Reversible, i.e., heat pump
With atmospheric condensate removal or prevention
C062S151000, C062S324600, C062S324100
Reexamination Certificate
active
06276158
ABSTRACT:
TECHNICAL FIELD
The present invention relates to heat exchange equipment comprising a compressor which is connected to a heat exchanger intended to be in contact with air for indoor circulation and also to two heat exchangers, both intended to be in contact with outdoor air, so that a heat exchange fluid can flow between the compressor and the heat exchangers, the equipment further comprising flow-direction changing means to change the direction of flow in the heat exchangers whereby each of the outdoor heat exchangers can be defrosted whilst the other continues to remove heat from its surroundings.
BACKGROUND OF THE INVENTION
Previously proposed such heat exchange equipment is disclosed in U.S. Pat. No. 5,771,699. This discloses an air conditioning system which employs reverse cycle refrigeration apparatus to condition air inside a building for heating in the winter months, and for cooling in the summer months, utilizing one heat exchanger coil disposed in heat exchange relation to the flow of conditioned air circulating within a building, and two heat exchanger coils disposed in heat exchange relation to the flow of ambient air circulating outside a building, wherein each heat exchanger coil comprises a separate and singular component part of a single air conditioning circuit connected to, and served by one single compressor; and wherein each of the outside heat exchanger coils are designed to change functions independently of the other, from that of an evaporator, to that of a condenser, for the purpose of inhibiting the accumulation of frost on, and/or removing frost from the outside heat exchanger coil when the heat pump is operating in the heating mode without reversing the flow of refrigerant within, or impeding the flow of refrigerant to the inside heat exchanger coil, whereby the inside heat exchanger coil will continue to function in the condenser mode, and will continue to furnish heat to the inside of a building during the defrost cycle of either of the said outside heat exchanger coils, and whereby heat generated by one said outside heat exchanger coil during the defrost cycle of that coil will be reabsorbed into the heat pump system via the other outside heat exchanger coil and circulated through the same refrigeration circuit, in a manner that will improve the efficiency of the heat pump.
Previously proposed equipment provides respective thermostatic control means for the outside coils. Furthermore, it is possible that both coils may require defrosting simultaneously.
SUMMARY OF THE INVENTION
The present invention seeks to obviate one or more of these disadvantages.
Accordingly, the present invention is directed to heat exchange equipment as set out in the opening paragraph of the present specification in which the equipment further comprises pressure lowering means between the two outdoor beat exchangers, and in which the fluid-direction changing means are provided between the compressor and the heat exchangers to enable a first direction of flow of the heat exchange fluid, wherein the latter passes from the indoor heat exchanger to one of the outdoor heat exchangers to defrost it, and thence to the other outdoor heat exchanger via the said pressure lowering means before it is returned to the compressor, so that the said other outdoor heat exchanger removes heat from its surroundings, and a second direction of flow of the heat exchange fluid, wherein the latter passes from the indoor heat exchanger to the said other outdoor heat exchanger to defrost it, and thence to the said one of the other outdoor heat exchangers via the said pressure lowering means, before it is returned to the compressor, so that the said one of the outdoor heat exchangers removes heat from its surroundings and in which the equipment further comprises control means connected so as to be able to issue control signals to the fluid-direction control valves to cause the latter to change the flow of the heat exchange fluid from one of the said first and second directions to the other.
The operation of the equipment as a heat pump to heat an indoor environment can alternate between a flow of the heat exchange fluid in the first direction and a flow of the heat exchange fluid in the second direction. Such flip-flop operation between the two directions of flow ensures that no more than one of the outdoor heat exchangers will need defrosting at any given time.
Preferably, the pressure lowering means comprises one pressure lowering device which serves both the outdoor heat exchangers, the flow direction changing means being such as to ensure that, for both the said first and second directions of flow of the heat exchange fluid, the latter passes through the said pressure lowering device in the same direction.
Preferably, the equipment further comprises defrost-threshold sensor means arranged to provide a signal indicative of when one or other of the outdoor heat exchangers requires defrosting, the control means being connected to receive signals from the defrost-threshold sensor means and to issue such a control signal upon receipt of a signal from the defrost-threshold sensor means.
One or more of the heat exchangers may comprise a coil, or a meandering passageway, for the flow of the heat exchange fluid.
The pressure lowering means may comprise a heat exchange fluid expansion device, which may simply be an orifice.
The heat exchange flow expansion device may comprise a thermostatic expansion valve. The latter may be adjustable to enable it to adjust the flow rate of fluid therethrough. Thus, if the expansion device comprises an orifice, the adjustability may be accomplished by adjusting the size of the orifice. Temperature-dependent control means may be incorporated in the adjustable expansion valve to adjust the latter in dependence upon the value of the temperature of the heat exchange fluid, preferably the heat exchange fluid flowing into the suction side of the compressor.
The defrost-threshold sensor means may be a temperature sensor. It may be located to provide an indication of the temperature of the heat exchange fluid where it flows between the two outdoor heat exchangers. In particular, the defrost-threshold sensor means may be located upstream of the pressure lowering means.
A fluid receiving vessel may be positioned upstream of the pressure lowering means. A fluid filter may be arranged between the fluid receiving vessel and the pressure lowering means to filter the heat exchange fluid which flows therebetween.
The heat exchange fluid may comprise a freon which may be a chlorofluoro hydrocarbon.
The compressor may comprise a positive displacement piston pump.
REFERENCES:
patent: 5105629 (1992-04-01), Parris et al.
patent: 5771699 (1998-11-01), Ponder
patent: 5832735 (1998-11-01), Matsumoto et al.
patent: 5852939 (1998-12-01), Gazes
patent: 6021644 (2000-02-01), Ares et al.
patent: 6102114 (2000-08-01), Nishihara et al.
Lowes Albert Robert
Luxford Mark Steven
Clark & Brody
Doerrler William
Eaton-Williams Group Limited
Shulman Mark
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