JPH0338592Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an air conditioner using a mixed refrigerant consisting of a high boiling point refrigerant and a low boiling point refrigerant.

FIG. 1 shows a conventional air conditioner using a mixed refrigerant consisting of a high boiling point refrigerant and a low boiling point refrigerant.
3. Evaporator 14.

During operation, as shown by the arrow in FIG. 1, the refrigerant compressed by the compressor 11 is condensed in the condenser 12, throttled by the throttle mechanism 13, evaporated in the evaporator 14, and sucked into the compressor 11. repeat.

FIG. 2 shows the refrigeration cycle of the air conditioner shown in FIG. 1 in a Mollier diagram. Figure 2 shows the enthalpy of the refrigerant on the horizontal axis and the pressure of the refrigerant on the vertical axis, where 21 is the saturated liquid line, 22 is the saturated vapor line, 23 is the critical point, and 24 is the saturated liquid line 21 and saturated vapor. The isotherm line between lines 22 and 25 indicates the line where the pressure is constant. Points 26 to 27 in Figure 2 are the refrigerant compression process, 27 to 28 are the condensation process, and 28 to 29
29 is the expansion process, and 29 to 26 are the evaporation processes.

In the conventional device shown in FIG. 1, as shown in the Mollier diagram in FIG. Since the direction is downward to the right as you move towards the direction, during operation the initial state of the evaporation process (point 29 in Figure 2) and the final state of the evaporation process (point 26 in Figure 2) are different. The difference in temperature is large, compared to when a single medium was used as a refrigerant.
In particular, when the outside temperature is low, the temperature of the refrigerant at the inlet of the evaporator 14 (point 29) decreases, and the portion that exchanges heat with the air near the inlet of the evaporator 14 has a high degree of frost formation. Driving was impaired by the influence. That is, in FIG. 2, if isotherm 24-1 (refrigerant evaporation temperature T ₀ °C) is the frosting temperature of the evaporator, then
In order to maximize the heat exchange capacity of the evaporator,
It is necessary to bring the evaporation temperature close to this frosting temperature 24-1. However, when a mixed refrigerant is used, the isothermal line descends to the right, so even if the temperature at the evaporator inlet 29 is set at the isothermal line 24-2 (T ₁ °C), which is close to the frosting temperature 24-1, no evaporation occurs at the evaporator outlet 26. The temperature will be T ₂ ℃,
When the temperature becomes higher than T ₁ °C, the heat exchange capacity of the evaporator decreases.

If the temperature at the evaporator inlet 29 is set lower to compensate for this decrease in capacity, there is a risk of frost formation at the evaporator inlet.

In view of the above, the present invention aims to prevent frost formation on the evaporator due to a temperature drop at the inlet of the evaporator of a refrigeration cycle using a mixed medium as a refrigerant. A pressure regulating valve is provided in between to adjust the pressure, and the evaporation pressure of the upstream evaporator can be arbitrarily set, thereby making it possible to adjust the temperature at the evaporator inlet. FIG. 3 shows a refrigerant system diagram of an air conditioner using a mixed refrigerant according to the present invention. In FIG. 3, 31 is a compressor, 32
33 is a condenser, 33 is a throttle mechanism, 34 is a first evaporator, 35 is a pressure regulating valve, and 36 is a second evaporator.

In FIG. 3, the mixed refrigerant during operation is compressed by a compressor 31, condensed by a condenser 32, throttled by a throttle mechanism 33, and transferred to a first evaporator 34, as shown by the solid line arrow in FIG. A part of the refrigerant is evaporated, the pressure is reduced by the pressure regulating valve 35, it is evaporated again by the second evaporator 36, and the refrigerant is sucked into the compressor 31 and compressed again.

FIG. 4 shows the refrigeration cycle of FIG. 3 in a Mollier diagram. In Figure 4, 41
is the saturated liquid line, 42 is the saturated vapor line, 43 is the critical point,
44 is an isothermal line between the saturated liquid line 41 and the saturated vapor line 42. (Now this isotherm 44 is the frosting temperature T ₀ ℃
In addition, points 46 to 47 in FIG. 4 are the compression process, 47 to 48 are the condensation process, 48 to 49 are the throttle expansion process, 49 to 50 are the evaporation process by the first evaporator 34, and 50 to 51 is the pressure reduction process by the pressure regulating valve 35, and 51 to 46 are the second evaporator 36.
This shows the evaporation process. Temperatures at the inlet state of the first evaporator 34 (point 49 in FIG. 4) and the inlet state of the second evaporator 36 (point 51 in FIG. 4) on the Mollier diagram in FIG. By adjusting the temperature in two stages using the throttling mechanism 33 and the pressure regulating valve 35 to bring it as close as possible to the frosting temperature T ₀ °C,
It is possible to prevent frost from forming on the inlet portions of the first evaporator 34 and the second evaporator 36 that come into contact with the air, and to increase the heat exchange capacity, so that stable operating conditions can be maintained.

In addition, in FIG. 3, the evaporator is divided into two parts, each of which is a first evaporator 34 and a second evaporator 36, with a pressure regulating valve 35 disposed between them. The same effect can be achieved even if the pressure regulating valve 35 is arranged between a large number of parts as shown in FIG. Furthermore, FIG. 3 shows a first evaporator 34 and a second evaporator 3.
Although a pressure regulating valve 35 is provided between the two evaporators 35 and 6, the effect is the same even if a large number of evaporators 37 and 39 are connected in parallel and a pressure regulating valve 38 is disposed between them as shown in FIG. It is.

[Brief explanation of the drawing]

Fig. 1 is a refrigerant system diagram of an air conditioner using a conventional non-azeotropic mixed refrigerant, Fig. 2 is a Mollier diagram of the same as above, Fig. 3 is a refrigerant system diagram of an embodiment of the present invention, and Fig. 4 is a Mollier diagram similar to the above, and FIGS. 5 and 6 are refrigerant system diagrams showing other embodiments of the present invention, respectively. Evaporator 34, 36, 37, 39, pressure regulating valve 3
5,38.

Claims (1)

[Scope of utility model registration request] An air conditioner using a mixed refrigerant consisting of a high boiling point refrigerant and a low boiling point refrigerant, characterized in that the evaporator is divided into a plurality of parts, and a pressure regulating valve for adjusting the pressure is arranged between the evaporators. Machine.