Heat exchange – With timer – programmer – time delay – or condition responsive... – Having heating and cooling capability
Reexamination Certificate
2002-07-22
2004-01-20
Tapolcai, William E. (Department: 3744)
Heat exchange
With timer, programmer, time delay, or condition responsive...
Having heating and cooling capability
C062S238700, C062S324600
Reexamination Certificate
active
06679321
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates, in general, to heat pump systems and, more particularly, to a heat pump system that uses air as its heat source.
2. Description of the Prior Art
As well known to those skilled in the art, a heat pump system is an air conditioning machine that is selectively used as a heater or a cooler by changing the refrigerant flowing direction in the system, as desired. That is, in a conventional heat pump system, a main refrigerant line starting from the outlet port of a compressor extends while sequentially connecting a four-way valve, an indoor heat exchanger, two expansion valves, and an outdoor heat exchanger to each other, prior to being ended at the four-way valve. In addition, the four-way valve is also connected to the inlet port of the compressor through a refrigerant suction line. During a heating mode operation of the heat pump system, the four-way valve controls the refrigerant flowing direction in the main refrigerant line such that high pressure and high temperature gas refrigerant outputted from the compressor flows to the indoor heat exchanger, which acts as a condenser for condensing the gas refrigerant while transmitting heat from the gas refrigerant to indoor air or water flowing around the indoor heat exchanger, thus heating the indoor air or producing hot water while condensing the gas refrigerant. In such a case, the heat pump system performs a heating, drying or hot water producing function. The high pressure and high temperature liquid refrigerant outputted from the indoor heat exchanger is expanded in the heating mode expansion valve. The refrigerant from the expansion valve is, thereafter, evaporated by heat at the outdoor heat exchanger acting as an evaporator using outdoor air as a heat source. At the outdoor heat exchanger, the liquid refrigerant thus becomes low pressure and low temperature gas refrigerant, which is returned to the compressor so as to accomplish one cycle. During the heating mode operation, the heat pump system repeats the above-mentioned cycle.
During a cooling mode operation of the heat pump system, the four-way valve controls the refrigerant flowing direction in the main refrigerant line such that the high pressure and high temperature gas refrigerant outputted from the compressor flows to the outdoor heat exchanger, which acts as a condenser for condensing the gas refrigerant while transmitting heat from the gas refrigerant to outdoor air used as a heat source of the condenser. At the outdoor heat exchanger, the high pressure and high temperature gas refrigerant thus becomes high pressure and high temperature liquid refrigerant, which is outputted to the cooler-mode expansion valve so as to be expanded in the expansion valve. The liquid refrigerant from the cooling mode expansion valve is evaporated by heat transmitted from indoor air or water, at the indoor heat exchanger acting as an evaporator. In such a case, due to the evaporation of the refrigerant at the indoor heat exchanger, the refrigerant absorbs heat from the indoor air or water flowing around the indoor heat exchanger, thus cooling the indoor air or producing cold water. At the indoor heat exchanger, the refrigerant thus becomes low pressure and low temperature gas refrigerant, which is returned to the compressor so as to accomplish one cycle. During the cooling mode operation, the heat pump system repeats the above-mentioned cycle.
During an evaporation of the liquid refrigerant using heat of outdoor air at the outdoor heat exchanger in a heating mode operation of the conventional heat pump system, moisture laden in the outdoor air may be frozen on the external surface of the outdoor heat exchanger when the temperature of the outdoor air is excessively low. In such a case, the frost formed on the external surface of the outdoor heat exchanger reduces the evaporation effect of the liquid refrigerant, thus remarkably reducing the heating capacity of the heat pump system. Therefore, the technique of promoting the evaporation of liquid refrigerant at the outdoor heat exchanger or promoting the evaporation of gas refrigerant inputted into the compressor of heat pump systems has been actively studied.
For example, Japanese Patent Laid-open Publication No. Sho. 54-45949 discloses an air conditioning apparatus, with a refrigerant heater installed on the refrigerant line of the apparatus and used as an evaporator during a heating mode operation of the apparatus. In a heating mode operation of the above Japanese air conditioning apparatus, high pressure and high temperature refrigerant outputted from a compressor is condensed at an indoor heat exchanger while heating indoor air. The refrigerant is, thereafter, dropped in its pressure at a heating mode pressure reducer, and evaporated at the refrigerant heater. Therefore, this air conditioning apparatus is not deteriorated in its heating capacity even when the apparatus is operated as a heater in cold outdoor air. In addition, Japanese Patent Publication No. Sho. 55-5017 discloses a heat pump type air conditioning apparatus, which has a plurality of outdoor heat exchangers, and a flow control unit. The flow control unit switches the refrigerant flow between a first cycle, in which the outdoor heat exchangers act as condensers at the same time in the case of a cooling mode operation, and act as evaporators at the same time in the case of a heating mode operation, and a second cycle, in which a part of high temperature gas refrigerant directly flowing from a compressor to an indoor heat exchanger is fed to the outdoor heat exchangers so as to allow one of the outdoor heat exchangers to alternately act as a condenser and an evaporator and, at the same time, allow the other outdoor heat exchanger to alternately act as an evaporator and a condenser. Another example of conventional heat pump systems is referred to U.S. Pat. No. 6,050,102, allowed to the inventor of the present invention and entitled “heat pump type air conditioning apparatus”. This heat pump type air conditioning apparatus comprises a compressor, a four-way valve, an indoor heat exchanger, a cooling mode capillary tube used as a pressure reducer, a heating mode capillary tube used as a pressure reducer, and an outdoor heat exchanger connected to each other by both a first refrigerant line and a gas refrigerant suction line. The above heat pump type air conditioning apparatus also has a first heat exchanger and a second heat exchanger. The first heat exchanger is installed on the first refrigerant line at a position between the indoor heat exchanger and the heating mode capillary tube. The second heat exchanger is installed on the first refrigerant line at a position between the outdoor heat exchanger and the four-way valve such that the second heat exchanger is positioned higher than the first heat exchanger. The second heat exchanger is also connected to the first heat exchanger through a connection line having an on-off valve, such that the first and second heat exchangers form a closed circuit. The first and second heat exchangers contain actuation fluid therein and vaporize both the remaining liquid refrigerant and incompletely vaporized gas refrigerant from the outdoor heat exchanger using the actuation fluid heated and vaporized by liquid refrigerant from the indoor heat exchanger.
In an operation of such a conventional heat pump system, liquid or gas refrigerant is evaporated or condensed at the outdoor heat exchanger using heat of outdoor air, and so the thermal capacity of the system is determined by the quantity of heat transmitted at the indoor heat exchanger. Typically, it has been well known to those skilled in the art that the heat exchanging surface area of the outdoor heat exchanger, determining the thermal capacity of the system, is set to about 1.2 to 1.4 times larger than that of the indoor heat exchanger.
In Japanese Patent Laid-open Publication No. Sho. 54-45949, it is described that a refrigerant heater is installed on the refrigerant line, and is used as an evaporator
Hedman & Costigan ,P.C.
Tapolcai William E.
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