Refrigeration – Processes – Employing diverse materials or particular material in...
Reexamination Certificate
1999-07-08
2001-06-19
Doerrler, William (Department: 3744)
Refrigeration
Processes
Employing diverse materials or particular material in...
C062S149000
Reexamination Certificate
active
06247320
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a refrigerating and air-conditioning apparatus using a non-azeotropic refrigerant, and more particularly to a refrigerating and air-conditioning apparatus which is capable of operating with high reliability and efficiency by accurately detecting the composition of the refrigerant which circulates in a refrigeration cycle using a non-azeotropic refrigerant in which three or more kinds of refrigerants are mixed.
First, a description will be given of the characteristics of the composition of a refrigerant which is circulated in a cycle of a refrigerating and air-conditioning apparatus using a non-azeotropic refrigerant.
FIG. 15
is a gas-liquid equilibrium diagram illustrating the characteristics of a non-azeotropic refrigerant in which two kinds of refrigerants are mixed, and the ordinate represents the temperature, while the abscissa represents a circulating composition (a composition ratio of low-boiling components), the parameter being the pressure. In the case of the two-kinds-mixed non-azeotropic refrigerant, a saturated vapor curve and a saturated liquid curve are determined by the pressure, as shown in FIG.
15
. The region located upwardly of the saturated vapor curve indicates a superheated vapor state, the region located downwardly of the saturated liquid curve indicates a supercooled state, and the region located between the saturated vapor curve and the saturated liquid curve indicates a gas-liquid two-phase state. In
FIG. 15
, Z denotes the circulating composition in a refrigeration cycle; a point
1
, an outlet portion of a compressor; a point
2
, an outlet portion of a condenser; a point
3
, an inlet portion of an evaporator; and a point
4
, an inlet portion of the compressor.
In general, in a refrigeration cycle using a non-azeotropic refrigerant, the composition of the refrigerant circulating in the cycle and the composition of the refrigerant charged in the cycle does not necessarily agree with each other. This is because, in the gas-liquid two-phase portion of the refrigeration cycle, which is shown by a point A in
FIG. 15
, the liquid composition becomes X which is smaller than the circulating composition Z, while the vapor composition becomes Y which is larger than the circulating composition. Particularly in a cycle in which an accumulator is provided in the piping between the outlet of the evaporator and the inlet of the compressor, if the liquid refrigerant accumulates in the accumulator, the circulating composition shows a tendency in which low-boiling components increase more than in the case of the charged composition. This is attributable to the fact that the liquid refrigerant, in which the amount of low-boiling components is smaller (the amount of high-boiling components is larger) than in the case of the charged composition, is accumulated in the accumulator.
In addition, even if the refrigerant in the refrigeration cycle has leaked outside, the circulating compositions in the cycle change. For example, if the leakage of the liquid refrigerant occurs in the gas-liquid two-phase portion shown by the point A in
FIG. 15
, the refrigerant with a composition X smaller than the circulating composition leaks, so that the circulating composition shows a tendency of becoming larger. On the other hand, if the vapor refrigerant leaks in the gas-liquid two-phase portion, the refrigerant with the composition Y larger than the circulating composition, so that the circulating composition shows a tendency of becoming smaller. Thus, in the cycle using the non-azeotropic refrigerant, the composition of the refrigerant circulating in the cycle changes substantially due to the operating condition of the cycle, the leakage of the refrigerant, and the like.
If the circulating composition in the cycle changes, the relationship between the pressure and the saturation temperature of the refrigerant changes, as can be seen from
FIG. 15
, and the cooling capabilities also change substantially. Accordingly, to make the cycle stable and allow predetermined capabilities to be demonstrated, it is necessary to accurately detect the circulating composition in the cycle, and optimally control the number of revolutions of the compressor, the amount of opening of a pressure reducing device, and the like in correspondence with the circulating composition.
FIG. 16
shows a configuration of a conventional refrigerating and air-conditioning apparatus using a non-azeotropic refrigerant, which is disclosed in, for example, Japanese Patent Application Publication. In the drawing, reference numeral
1
denotes a compressor ;
2
, a condenser;
33
, a receiver;
3
, a pressure reducing device; and
4
, an evaporator, and these component elements are consecutively connected by pipes and constitute a refrigeration cycle. As a refrigerant, a non-azeotropic refrigerant in which two kinds of refrigerants, including a high-boiling component and a low-boiling component, are mixed is used. In addition, a temperature detector
34
and a pressure detector
35
are provided for a receiver
33
at an outlet of the condenser
2
, and signals from these detectors are inputted to a composition calculator
10
.
With the conventional refrigerating and air-conditioning apparatus using a non-azeotropic refrigerant, which is figured as described above, the vapor of the high-temperature, high-pressure non-azeotropic refrigerant which is compressed by the compressor
1
is condensed and liquefied by the condenser
2
, and flows into the receiver
33
. This liquid refrigerant is passed through the pressure reducing device
3
, where it is converted to a low-temperature, low-pressure gas-liquid two-phase refrigerant, and flows into the evaporator
4
, where it is evaporated and returns to the compressor
1
. The circulating composition in the cycle is calculated by the composition calculator
10
on the basis of information on the temperature and pressure of the liquid refrigerant which has flown into the receiver
33
, the temperature and pressure having been detected by the temperature detector
34
and the pressure detector
35
. That is, a gas-liquid equilibrium diagram such as the one shown in
FIG. 17
is obtained from the kind of the charged non-azeotropic refrigerant in which two kinds of refrigerants are mixed, as well as the pressure PH detected by the pressure detector
35
. If it is assumed that the state of the refrigerant in the receiver
33
is that of a saturated liquid, the circulating composition Z in the cycle can be detected from a point of intersection of the saturated liquid curve and the temperature TH detected by the temperature detector
34
, as shown in FIG.
17
.
If this basic principle of detection of the circulating composition is expanded, in the case of the two-kinds-mixed non-azeotropic refrigerant, the circulating composition can be detected if the quality of wet vapor, X, (=the flow rate of the mass of refrigerant vapor/the flow rate of the total mass of the refrigerant), as well as the temperature and pressure of the refrigerant at this quality of wet vapor, X, are known. That is, in the case of the two-kinds-mixed non-azeotropic refrigerant, in a case where the pressure P is fixed, the relationship such as the one shown by the dot-dashed line in
FIG. 18
, which illustrates the conventional basic principle of detection of circulating compositions of the two-kinds-mixed refrigerant, is present between the temperature and the circulating composition Z of the refrigerant at the quality of wet vapor, X, including the saturated vapor curve where the quality of wet vapor, X, =1 and the saturated liquid line where the quality of wet vapor, X, =0. Accordingly, by using this relationship, it is possible to detect the circulating composition in the cycle if the pressure, temperature, and quality of wet vapor of the refrigerant in the gas-liquid two-phase state, including the saturated vapor and the saturated liquid, can be known.
However, although this method can be applied to the two-kinds-mixed refr
Kasai Tomohiko
Morimoto Osamu
Okazaki Takashi
Sumida Yoshihiro
Ueno Yoshio
Burns Doane , Swecker, Mathis LLP
Doerrler William
Jones Melvin
Mitsubishi Denki & Kabushiki Kaisha
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