Refrigeration – Refrigeration producer – Compressor-condenser-evaporator circuit
Reexamination Certificate
2000-12-29
2003-02-25
Doerrler, William C. (Department: 3744)
Refrigeration
Refrigeration producer
Compressor-condenser-evaporator circuit
C062S513000
Reexamination Certificate
active
06523365
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an accumulator with an integral heat exchanger for use in an air conditioning or refrigeration system. In particular, the heat exchanger is positioned inside the accumulator such that liquid refrigerant from the high pressure, high temperature side of the system and gaseous refrigerant from the low pressure, low temperature side of system simultaneously flow through the heat exchanger in a heat exchange relationship. The accumulator of the present invention may be used with a variety of refrigerants including R134
a
and carbon dioxide, despite the higher operating pressures inherent in a system using carbon dioxide as the refrigerant.
A basic refrigeration or air conditioning system has a compressor, a condenser, an expansion device, and an evaporator. These components are generally serially connected via conduit or piping and are well known in the art. During operation of the system, the compressor acts on relatively cool gaseous refrigerant to raise the temperature and pressure of the refrigerant. From the compressor, the high temperature, high pressure gaseous refrigerant flows into the condenser where it is cooled and exits the condenser as a high pressure liquid refrigerant. The high pressure liquid refrigerant then flows to an expansion device, which controls the amount of refrigerant entering into the evaporator. The expansion device lowers the pressure of the liquid refrigerant before allowing the refrigerant to flow into the evaporator. In the evaporator, the low pressure, low temperature refrigerant absorbs heat from the surrounding area and exits the evaporator as a saturated vapor having essentially the same pressure as when it entered the evaporator. The suction of the compressor then draws the gaseous refrigerant back to the compressor where the cycle begins again.
In a typical air conditioning or refrigeration system, it is necessary to prevent liquid from passing from the evaporator into the compressor in order to avoid damage to the compressor. When liquid refrigerant enters a compressor, it is known as slugging. Slugging reduces the overall efficiency of the compressor and can also damage the compressor. It is well known in the art to mount a suction line or low pressure side accumulator between the evaporator and compressor. Such suction line accumulators act to separate the liquid and gaseous phases of the refrigerant flowing from the evaporator. The liquid portion of the refrigerant will settle to the bottom of the accumulator while the gaseous phase will rise to the top of the accumulator and will be suctioned out of the accumulator by the compressor.
It is also known in the art to have an accumulator with a heat exchanger arranged on both the high pressure and low pressure sides of an air conditioning or refrigeration system.
FIG. 1
is a schematic of a system having an accumulator arranged on both the high pressure and low pressure sides of the system. In general, high pressure, high temperature refrigerant exits a compressor
1
and flows into a condenser
3
. The high temperature liquid refrigerant exits the condenser and flows into a heat exchanger located in an accumulator
5
. The refrigerant is discharged from the accumulator and flows into an expansion device
7
and subsequently into an evaporator
9
.
At the same time, low temperature, low pressure refrigerant flowing from the evaporator
7
enters the accumulator and the liquid phase settles to the bottom of the accumulator, and the gaseous phase rises. The low temperature gaseous refrigerant then flows through the heat exchanger where it comes in contact with the high pressure, high temperature liquid refrigerant from the condenser in a heat exchange relationship. The high pressure liquid from the condenser
3
is then cooled by the low pressure, low temperature gaseous refrigerant running simultaneously through the heat exchanger. As a result, the liquid refrigerant flowing from the condenser
3
to the evaporator is cooled and can thereby absorb more heat as it flows through the evaporator
7
. The gaseous refrigerant exiting the low pressure side of heat exchanger is higher in temperature having absorbed heat from the high pressure, high temperature liquid refrigerant. As a result, any liquid refrigerant that may remain in the low pressure, low temperature refrigerant will be converted into a gas in the heat exchanger thereby reducing the risk of having liquid flow into the compressor.
U.S. Pat. Nos. 5,622,055, 5,245,833, 4,488,413, and 4,217,765 disclose accumulators with internal heat exchangers. In these patents, high pressure, high temperature refrigerant from the condenser is cooled as it flows through a tube that is sitting in a pool of low temperature liquid refrigerant that has been discharged from the evaporator and collected in the accumulator.
GB Patent No. 2316738B also discloses a low pressure side accumulator with an internal heat exchanger. The accumulator is divided into an upper and lower chamber. The heat transfer unit, two serially connected tubes, is housed in the lower chamber. High temperature, high pressure refrigerant flowing from the condenser enters one end of the tubes and exits the other end and then flows to an expansion device evaporator. At the same time, low pressure, low temperature refrigerant from the evaporator is discharged into the upper chamber. The refrigerant in the upper chamber is drawn into the lower chamber where it flows through the lower chamber in a heat exchange relationship with high pressure, high temperature refrigerant flowing through the tubes before being discharged from the accumulator and drawn back to the compressor.
U.S. Pat. Nos. 5,457,966 and 5,289,699 disclose a high pressure side accumulator with internal heat exchanger. In one embodiment, the heat exchanger comprises an outer shell with right and left end plates and an outer tube with a cutaway portion located within the shell. An inner tube is housed within the outer tube and extends through the shell and both end plates. In operation, high pressure, high temperature liquid refrigerant from the condenser enters an inlet line, which flows into the outer tube. The liquid refrigerant flows through the outer tube and into the shell at the cut away portion. The liquid refrigerant is discharged from the shell through an outlet line. At the same time, low pressure, low temperature refrigerant from the evaporator enters the smaller tube and flows through the inner tube in a heat exchange relationship with the high pressure, high temperature refrigerant before flowing back to the compressor.
In a second embodiment, the heat exchanger housed within the shell comprises a small oval shaped tube affixed to one side of a large tube. The larger tube extends through the entire length of the shell. High pressure, high temperature liquid refrigerant from the condenser enters one end of the oval shaped tube and exits the other end and flows into the shell. Liquid refrigerant exits the shell through an outlet line and flows to the evaporator. Simultaneously, low pressure, low temperature refrigerant flows from the evaporator through the large tube in a heat exchange relationship with the high pressure, high temperature refrigerant. The low pressure, low temperature refrigerant exiting the larger tube flows back to the compressor. A third embodiment is similar to the second embodiment except that the smaller tube is spirally wrapped around the outside of the larger tube.
U.S. Pat. No. 3,830,077 discloses a heat exchanger for use in a vehicle, which is connected between the evaporator and compressor. The heat exchanger comprises an outer shell with low pressure, low temperature inlet and outlet lines and at least one heat exchange coil, with an inlet end an outlet end both extending through the shell. In operation, low pressure, low temperature refrigerant enters the inlet line, flows through the shell, exits the outlet line and flows back to the compressor. At the same time a high temperature vehicle fluid flows through the coil in a heat e
Gibbons, Jr. Richard G.
Mehraban Henry
Urdea Teodor
Zhang Chao A.
Brinks Hofer Gilson & Lione
Doerrler William C.
Visteon Global Technologies Inc.
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