JPH0136025B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a refrigeration cycle equipped with a thermostatic automatic expansion valve, and particularly relates to a working medium sealed in the thermostatic automatic expansion valve and a circulating refrigerant sealed in the refrigeration cycle. It is related to.

[Prior art]

The temperature-sensitive cylinder of a thermostatic automatic expansion valve used in ordinary refrigeration equipment is generally filled with the same refrigerant as that used in the refrigeration cycle. In such a refrigeration cycle, periodic unstable phenomena such as pressure or temperature (hereinafter referred to as hunting) often occur in the refrigeration system due to branching of the refrigerant flowing into the evaporator or imbalance in heat load. Conventionally, as a means to avoid this hunting, the adjustment spring of the expansion valve is strengthened to increase the stationary superheat, and the superheat of the evaporator is increased to stabilize the temperature of the temperature-sensitive tube provided at the evaporator outlet. Hunting is stopped by damping the periodic opening and closing of the valve. However, such a method reduces the capacity of the evaporator and significantly reduces the refrigeration capacity. Furthermore, if this method does not stop hunting, you may need to replace the expansion valve with one with a smaller capacity, fill the thermosensor with a special gas, or reduce temperature fluctuations as disclosed in Japanese Patent Publication No. 47-23825. Countermeasures have been taken, such as changing the time constant of the response speed of the thermosensor.

[Purpose of the invention]

The present invention was invented in view of the above, and an object of the present invention is to provide a refrigeration system that improves the evaporator capacity and growth coefficient of the refrigeration system, and prevents hunting of a thermostatic automatic expansion valve.

[Summary of the Invention] In order to achieve the above object, the present invention includes a single fluorocarbon refrigerant sealed as a working medium in a thermostatic automatic expansion valve, and the same refrigerant as the heat-sensitive cylinder sealed refrigerant as the sealed circulating refrigerant in a refrigeration cycle. The refrigerant is characterized by containing a non-azeotropic mixed refrigerant consisting mainly of , and a non-azeotropic refrigerant with a higher boiling point.

When a non-azeotropic high boiling point refrigerant is added to a certain refrigerant,
Under the same pressure conditions, the evaporation temperature becomes higher. Moreover, the evaporation temperature of this mixed refrigerant is not constant, and as the evaporation action progresses, the evaporation temperature increases. If a thermostatic automatic expansion valve in which refrigerant containing only low boiling point components is sealed in a temperature-sensitive tube is used in this mixed refrigerant cycle, the degree of superheat at the evaporator outlet can be reduced. Taking advantage of these characteristics, the refrigeration cycle is additionally filled with a non-azeotropic high-boiling refrigerant that has characteristics that improve cycle operating efficiency in addition to the main refrigerant with low-boiling components, and the temperature-type automatic expansion valve is equipped with a thermostatic expansion valve. If you use a hot cylinder filled with only the main refrigerant with the above-mentioned low boiling point components,
While the degree of superheating at the evaporator outlet is reduced to increase the coefficient of performance, even if some liquid returns to the evaporator outlet, the sensing temperature level of the thermosensor tube is higher than when only the main refrigerant is used, and therefore the sensing temperature changes. Since it is held down small, hunting is less likely to occur.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

In Fig. 1, 1 is a compressor, 2 is a condenser, and 3 is a compressor.
Reference numeral 4 indicates a thermostatic automatic expansion valve, and 4 indicates an evaporator, and a refrigeration cycle is formed by sequentially connecting each of the above-mentioned devices with piping. Here, the temperature-sensitive cylinder 3' of the thermostatic automatic expansion valve 3 is filled with a single-component fluorocarbon refrigerant, and the refrigeration cycle mainly contains the same refrigerant as in the temperature-sensitive cylinder, but with a higher boiling point than this. with the addition of a non-azeotropic refrigerant of
A so-called non-azeotropic mixed refrigerant is enclosed. Here, as an example, the thermosensor tube 3' is equipped with fluorocarbon refrigerant R22.
However, let us also consider a case where the refrigeration cycle is mainly filled with fluorocarbon refrigerant R22 and an additional n% of fluorocarbon R114. In this refrigeration cycle, gas refrigerant compressed to high temperature and high pressure by the compression action of the compressor 1 enters the condenser 2 and is condensed and liquefied.Then, the pressure is reduced by the expansion valve 3 and guided to the evaporator 4, where it performs a cooling action. . Here, it evaporates and vaporizes, and returns to the suction side of the compressor 1 to form a refrigerant circuit. The amount of refrigerant circulated within the refrigeration cycle is controlled by a temperature sensing cylinder 3' attached to the outlet pipe 7 of the evaporator 4. The pressure of evaporator 4 is P ₀
(=constant), the state of the refrigerant on the secondary side of the expansion valve 3, inside the temperature sensing cylinder 3', and inside the evaporator 4 is
It is expressed as shown in Fig. 3. In FIG. 2, curve A shows the saturated vapor pressure line of R22, and curve B shows the pressure obtained by adding pressure corresponding to the adjustment spring force of the expansion valve to curve A. The expansion valve 3 corresponds to the spring force that adjusts the temperature-sensitive cylinder internal pressure P ₁ (A ₁ point) due to the detected temperature t ₁ of the temperature-sensing cylinder 3', and the secondary side pressure P ₀ (A ₀ point) of the expansion valve 3. The pressure (point A ₀ ') that is the sum of this pressure forms the opening force and stopping force of the valve, respectively, and when these are balanced, the valve opening is maintained at a constant degree. At this time,
Since a mixed refrigerant is sealed in the refrigeration cycle, the saturation temperature of the evaporator internal pressure P ₀ (assuming there is no pressure loss in the evaporator and the same pressure P ₀ from the evaporator inlet to the outlet) is , is different from the saturation temperature t ₀ at the pressure P ₀ of R22, and has a higher value. Therefore, the degree of superheating of the refrigerant at the outlet of the evaporator 4 has a value smaller than t ₁ −t ₀ . The degree of superheating at this time is explained with reference to FIG. Here, curves C and D are mixed refrigerant R22
- Shows the saturated liquid line and saturated vapor line at constant pressure P ₀ of the R114 system. enclosed within the refrigeration cycle
The liquefied mixed refrigerant having an R114 concentration of n% in R22 is depressurized by the expansion valve 3 and flows into the evaporator 4 in a state xm at a temperature tm containing some gas. temperature tm pressure
Higher than the saturation temperature t ₀ of R22 at P ₀ and lower than the saturation temperature t ₁₀ of R114. This refrigerant acts as a cooling agent within the evaporator 4 and gasifies itself while increasing its evaporation temperature. Gasification is completed at xg state with temperature tg,
Thereafter, the degree of superheating of the gas increases in response to the rise in temperature. Now, the outlet temperature of evaporator 4 is t′g (x′g state)
Then, the degree of superheat of the refrigerant is tg' - tg. temperature
Since t′g is equal to the sensing temperature t ₁ of the thermosensor tube in Fig. 2, the refrigerant mixture in the refrigeration cycle is R22.
This is considerably smaller than the superheat degree t ₁ −t ₀ (or tg′−t ₀ ) in the case of

In this way, in the refrigeration cycle of this embodiment, even if liquid components still remain at the evaporator outlet due to load fluctuations or imbalances in the refrigerant distribution state, the refrigeration cycle can be significantly reduced from the saturated gas temperature tg. There will be no decline. Furthermore, even if hunting should occur, its width will be approximately tg' - tg, which can be kept much smaller than tg' - t ₀ in the case of a conventional R22 100% refrigeration cycle. At the same time, the heat transfer area can be used effectively without reducing the capacity of the evaporator. Furthermore, the coefficient of performance can be improved by enclosing a suitable combination of refrigerants such as R22 (approximately 90%) and R114 (approximately 10%) and a mixed refrigerant at a mixed ratio.

[Results of the invention]

As explained above, according to the present invention, the following effects are achieved by using an appropriate combination of mixed refrigerants and reducing the degree of superheating at the evaporator outlet.

(1) The coefficient of performance can be improved.

(2) The heat transfer area of the evaporator can be used effectively.

(3) Hunting of the expansion valve can be prevented.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of a refrigeration cycle showing an embodiment of the present invention, Fig. 2 is an explanatory diagram of the operating state of the expansion valve shown in Fig. 1, and Fig. 3 is a state of the R22-R114 mixed refrigerant. It is a diagram. 1... Compressor, 2... Condenser, 3... Temperature-type automatic expansion valve, 3'... Temperature-sensitive cylinder, 4... Evaporator.

Claims (1)

[Scope of Claims] 1 A compressor, a condenser, a temperature-type automatic expansion valve, and an evaporator are sequentially connected via piping to form a refrigeration cycle, and the above-mentioned temperature-type automatic expansion valve is provided on the outlet side pipe of the evaporator. Inside the heat-sensitive cylinder, a single fluorocarbon refrigerant is sealed as a working medium and as a refrigerant component, and the circulating refrigerant in the refrigeration cycle is mainly the same refrigerant as the above-mentioned refrigerant sealed in the heat-sensitive cylinder. A refrigeration device characterized in that a non-azeotropic mixed refrigerant mixed with a non-azeotropic refrigerant is sealed. 2. The refrigeration system according to claim 1, wherein the refrigerant sealed in the heat-sensitive cylinder is Freon R-22. 3. The refrigeration system according to claim 1 or 2, wherein the refrigerant sealed in the refrigeration cycle is a non-azeotropic refrigerant mainly composed of Freon R-22 and mixed with R-114.