Refrigeration – Intermediate fluid container transferring heat to heat... – Flow line connected transfer fluid supply and heat exchanger
Reexamination Certificate
2000-04-14
2001-12-11
Doerrler, William (Department: 3744)
Refrigeration
Intermediate fluid container transferring heat to heat...
Flow line connected transfer fluid supply and heat exchanger
C062S267000, C062S431000, C062S432000, C062S441000, C062S442000
Reexamination Certificate
active
06327871
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to refrigerators and refrigeration cycles with a thermal storage.
BACKGROUND OF THE INVENTION
The present invention relates to freezers and refrigerators. More particularly the present invention relates to household and commercial freezers and refrigerators with multiple compartments: including freezing or frozen food compartments and refrigeration or fresh food compartments.
For most of refrigerators and freezers, a compression refrigeration system is the source of negative thermal potential. Compression refrigeration system consists of a compressor, a condenser, a metering/expansion device, and a low temperature evaporator installed in a freezing compartment. In refrigerators the refrigeration compartment is connected to the freezing compartment through the openings in the mullion or clearance between the mullion and the refrigerator case. Low temperature evaporator cools air in the freezing compartment. Refrigeration compartment is mostly cooled when cold air from the freezing compartment flows into the refrigeration compartment and cools the air in the compartment, although part of the cooling potential comes into the refrigeration compartment due to the heat transfer through the mullion. The air movement between the compartments is by forced or natural convection.
It is widely recognized, however, that the cooling of the refrigeration compartment by low temperature potential from the freezing compartment reduces the refrigeration capacity and efficiency. Also the air circulation between both compartments causes drying of the food in the refrigeration compartment and excessive frost building in the freezing compartment.
Some designers have attempted to overcome these problems by installation of two evaporators: a low temperature evaporator in the frozen food compartment and a high temperature evaporator in the fresh food compartment. There is no necessity for any clearance or openings in the mullion separating the compartments. Thus, there is no air circulation between the compartments. That eliminates moisture movement between two compartments and reduces consumption of electricity. Yet, because the refrigeration system provides much higher capacity to the high temperature evaporator, to sustain high efficiency this evaporator must be big in size with preferably forced air convection. Otherwise, the temperature of the evaporator drops down considerably, thus decreasing efficiency of refrigeration. In refrigerators with variable speed compressor high temperature operation requires low compressor speed. Still the evaporator has to have relatively large heat transfer surface. Another problem for refrigerators with two separate evaporators is the existence of temperature swings in the fresh food compartment. Unlike frozen food that has both latent and sensible heat, specific heat of fresh food itself consists only of sensible heat. It means that at the time when the compressor is off, the temperature in the refrigeration compartment quickly rises. On the other hand, the proper food preservation limits the temperature range for refrigeration. It causes excessive number of power switching of the compressor, which, in turn, reduces its efficiency and reliability. Even with extra insulation of the fresh food compartment, if the refrigerator door is open for some time, or somebody puts a new warm portion of fresh food and/or water into the compartment, compressor should start operating. In a refrigerator with variable speed majority of the time the compressor can run with low speed and jump the speed when the door is open. However, low speed operation is not very efficient, besides, in systems with the capillary tube as an expansion device changing of refrigerant flow rate causes reduction in the system efficiency. To overcome these problems some designers use a thermal storage in the fresh food compartment. However, known designs of a thermal storage for refrigerators are complicated and expensive.
In freezers and most of the contemporary refrigerators the biggest part of the negative thermal potential escapes through the walls and doors of the freezing compartment. Thus, in freezers and even in refrigerators that have two separate evaporators the increase of the low temperature operation efficiency is extremely important.
The present invention relates to freezers and different refrigerators. The preferred refrigerators, disclosed herein, are refrigerator-freezers that include side-by-side models with and without the ice/water dispenser in the door, models with the freezer mounted on the top or at the bottom of the refrigeration cabinet, and models with multiple compartments.
SUMMARY OF THE INVENTION
According to the present invention, a refrigerator with at least one of refrigeration and/or freezing compartments and a compression refrigeration system operable in at least one of either a medium/low temperature cooling mode or a high/medium temperature cooling mode is provided. The compression refrigeration system comprises of a refrigerant circuit including a compressor and, in serial connection a compressor discharge line, a condenser, a first expansion device, a thermal storage with a thermal storage medium, a second expansion device, an evaporator, and a compressor suction line; a refrigerant bypass line for bypassing the second expansion device; a valve positioned to block flow through the bypass line, and control means for controlling the valve and the compressor.
The compression refrigeration system further comprises a first capillary tube as the first expansion device and a second capillary tube as the second expansion device. Further the first and the second capillary tubes of the refrigeration system are in heat transfer communications with the compressor suction line.
According to one aspect of the invention, an inlet of the bypass line is connected to the thermal storage and an outlet of the bypass line is connected to the evaporator, further the valve of the refrigeration system is a shut-off valve. According to another aspect of the invention, the inlet of the bypass line is also connected to the thermal storage and the outlet of the bypass line is connected to the compressor suction line, the valve is either a shut-off valve or a three-way valve. The compression refrigeration system with a three-way valve further comprises a check valve after the evaporator to block refrigerant flow from the compressor suction line to the evaporator.
Further in accordance with the present invention, the compression refrigeration system comprises a fan moving air around surfaces of the thermal storage to deliver the high/medium temperature cooling potential to the refrigeration compartment. The thermal storage consists of a container with a phase change material as a thermal storage medium, and a refrigerant coil to evaporate refrigerant that extracts heat from the thermal storage medium and to condense and subcool refrigerant that rejects heat to the thermal storage medium.
According to a yet further aspect of the present invention, the thermal storage container and the refrigerant coil are roll-bonded from metal sheets, wherein two internal sheets with formed internal channels make the refrigerant coil and external sheets with formed external channels make the thermal storage container for the thermal storage medium that is located between external walls of the internal sheets and internal walls of the external sheets. In accordance with another aspect of the invention, the thermal storage container is filled with water and opened to air, and the refrigerant coil is submerged in water in the container with fins emerging from water to increase heat transfer surface contacting with the air.
Further in accordance with the present invention, a refrigerator with refrigeration and/or freezing compartments is provided. The refrigerator comprises a compressor with suction and discharge ports, the compressor insulated from the compartments, a condenser outside of the compartments, insulated side, top, bottom and back walls, at
Doerrler William
Shulman Mark
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