JPS6112540Y2 - - Google Patents

Description

[Detailed description of the invention] In the conventional refrigeration system, as shown in the flow diagram in Fig. 1, the refrigerant is transferred through the compressor 1 → condenser 2 → liquid receiver 3 → expansion valve 4 → evaporator 5 → compressor 1. In this refrigerant circulation circuit, (i)
When the outside temperature drops in winter, the high pressure (condensation pressure) decreases, so the differential pressure across the expansion valve 4 becomes small, making it difficult for the refrigerant to flow, and therefore not enough refrigerant flows to the evaporator 5, which reduces the evaporation pressure. (ii) Due to the low refrigerant flow rate, the lubricating oil of the compressor does not return properly from the evaporator 5 to the compressor 1, resulting in poor lubrication of the lubricated parts of sliding parts such as bearings. In severe cases, there is a drawback that the compressor 1 may be burnt out.

Therefore, in order to eliminate these drawbacks, the second
As shown in the figure, a refrigerant circuit is also known which is provided with a high-pressure control valve 6 that bypasses the condenser 2 shown in FIG. That is, in this refrigerant circuit, refrigerant normally circulates as follows: compressor 1 → condenser 2 → high pressure control valve 6 → liquid receiver 3 → expansion valve 4 → evaporator 5 → compressor 1, but in winter when the outside air temperature drops Then, the high pressure control valve 6 opens, and a portion of the refrigerant flows in parallel with the above circulation circuit from the compressor 1 to the bypass pipe 7 to the high pressure control valve 6 to the liquid receiver 3 to the expansion valve 4 to the evaporator 5 to the compressor 1. A part of the refrigerant gas discharged from the compressor 1 bypasses the condenser 2 and flows through the bypass pipe 7, maintaining the high pressure so that the high pressure does not fall below a certain pressure.

However, in this refrigerant circuit, when the high pressure control valve operates to maintain the high pressure above a certain pressure in winter, the refrigerating capacity is constant and the required power is also constant, so compared to the refrigerant circuit in Figure 1, When the outside temperature is low, the refrigeration capacity is small and the required power is large, resulting in operation with poor refrigeration efficiency.

In view of these circumstances, the present invention has been designed to achieve EER (Energy Efficiency) even under low outside temperatures in winter.
The purpose is to provide an energy-saving refrigeration system that increases the refrigerating capacity/input Kcal/h/w, and includes a compressor, air-cooled condenser, liquid receiver, expansion valve,
In a refrigeration system in which a refrigeration circuit is constructed by connecting evaporators in this order, the air-cooled condenser is divided into a plurality of parts, a switching valve is inserted between them, and the plurality of air-cooled condensers are sequentially connected via the switching valve. A circuit for flowing refrigerant into the liquid receiver through the air-cooled condenser, and a circuit for introducing the refrigerant condensed in a part of the air-cooled condenser into the liquid receiver and flowing it through the remaining air-cooled condenser, depending on the outside temperature. The present invention is characterized in that the switching valve is switched by the operator.

An embodiment of the present invention will be explained with reference to the drawings.
3 is a flow diagram, FIG. 4 is a Mollier diagram of FIG. 3, and FIGS. 5 to 10 are flow diagrams showing combinations of various switching valves for switching the condenser shown in FIG. 3, respectively.

First, in FIG. 3, 11 is a compressor, 12 is a first condenser, 13 is a second condenser, 14 is a liquid receiver,
15 is an expansion valve, 16 is an evaporator, and 17 is a four-way valve interposed between the first condenser 12, the second condenser 13, and the liquid receiver 14.

In this way, the condensers are the first condenser 12 and the second condenser 12.
When the outside air temperature is high in summer, the four-way valve 17 is switched to the position shown by the solid line, and the refrigerant is transferred from the compressor 11 to the first condenser as shown by the solid line arrow. A refrigeration cycle is performed by circulating in the order of 12 → four-way valve 17 → second condenser 13 → liquid receiver 14 → four-way valve 17 → expansion valve 15 → evaporator 16 → compressor 11, but the outside air temperature is low in winter. In this case, the four-way valve 17 is switched to the position shown by the broken line, and the refrigerant is transferred from the compressor 11 to the first condenser 12 to the four-way valve 17 to the liquid receiver 14 to the second condenser 13 to the four-way valve as shown by the broken line arrow. A refrigeration cycle is performed by circulating in the order of 17→expansion valve 15→evaporator 16→compressor 11.

Therefore, since the first condenser 12 and the second condenser 13 are used as condensers during the refrigeration operation during high outside air temperatures in summer, there is no difference from a general refrigeration system.

However, when the outside air temperature is low in winter, by using only the first condenser as a condenser, the condensing capacity is reduced and the high pressure (condensing pressure) is maintained high, so that high pressure control is performed.

On the other hand, the second condenser 13 cools the liquid refrigerant that has exited the liquid receiver 14 and functions not as a condenser but as a sub-cooling coil, so that the refrigerating capacity can be greatly increased.

As an example, the refrigeration capacity of a refrigeration system using refrigerant R502 during winter refrigeration operation is compared with that of the known refrigeration system shown in FIG. 2 as follows.

In other words, if the difference between the outside air temperature and the condensation temperature is 15°C, the evaporation temperature is -40°C, and the outside air temperature is 0°C, then as shown by the broken line in the Mollier diagram in Figure 4, in the case of the refrigeration system in Figure 2, When the condensing temperature is controlled to +30℃ using the high pressure control valve, Condensing temperature...+30℃ Evaporation temperature...-40℃ Liquid temperature before expansion valve (5° supercooled)...+25℃...Enthalpy 107.05kcal/Kg Evaporator outlet gas temperature ( 5° overheating)...-35℃...The enthalpy is 131.35kcal/Kg, so the freezing effect is 131.35-107.05=
It is 24.3kcal/Kg.

On the other hand, in the refrigeration system of the present invention, the size of the first condenser 12 is 50% of that shown in Fig. 2, and the difference between the outside air temperature and the condensing temperature is 30°C, that is, when the outside air temperature is 0°C, the condensing temperature is 30°C. ℃, and the liquid refrigerant cooled by the second condenser 13, which acts as a subcooling coil, is
Assuming that it is supercooled by 20°C, the expansion valve liquid refrigerant temperature is 30°-30° because it is supercooled by 5° at the condenser outlet.
20° + 5° = 5°C, and the situation in this case can be summarized as follows (see solid line in Figure 4).
That is, condensing temperature...+30℃ Evaporation temperature...-40℃ First condenser outlet liquid temperature (5° supercooling)...25°C Subcooling coil outlet liquid temperature (20° supercooling)...
+5℃...enthalpy 101.37kcal/Kg Evaporator outlet temperature (5° superheated)...-35℃...enthalpy 131.35kcal/Kg, so the refrigeration effect is 131.35-101.37=
It is 29.98kcal/Kg.

Therefore, when comparing the refrigeration system of the present invention with that shown in Fig. 2, the refrigerating capacity = 29.98/24.3 = 0.234 In other words, under low outside temperature, the refrigeration system of the present invention has a lower refrigerating capacity than that shown in Fig. 2. will increase by 23.4%. Incidentally, the required power is the same since the condensing temperature and the evaporation temperature are the same.

In the above embodiment, a four-way valve was used to switch the refrigerant circuit that flows through the condenser, but instead of the four-way valve,
Various combinations can be made, such as using a 3-way valve, using a solenoid valve (2-way valve), and using a combination of a check valve and a 3-way valve or a solenoid valve. Some examples are listed below.

Figure 5 shows solenoid valves 21, 22, 23 and check valve 3.
1, 32, Fig. 6 shows a 3-way valve 41, solenoid valves 21, 22, check valves 31, 32, and Fig. 7 shows a solenoid valve 21, 22, 23, 24, check valve. One using valves 31 and 32, Fig. 8 shows a three-way valve 4
1, 42, one using check valves 31, 32, No. 9
The figure shows three-way valves 41, 42, solenoid valve 21, and check valve 31.
Fig. 10 shows one using three-way valves 41, 42, and a solenoid valve 21, respectively.The solid arrow indicates the flow of refrigerant during high outside air temperature in summer, and the flow in all directions during low outside air temperature in winter is shown in Fig. 10. Flow through the valves is indicated by dashed arrows, respectively.

Furthermore, by dividing the condenser into three or more instead of two, it is possible to finely control the refrigerating capacity as described below. In other words, summer...1st condenser → 2nd condenser → 3rd condenser →
Receiver Intermediate period: 1st condenser → 2nd condenser → Receiver → 3rd condenser (1st sub-cooling coil) Winter period: 1st condenser → Receiver → 2nd condenser (1st
subcool coil) → 3rd condenser (2nd
In short, according to the present invention, in a refrigeration system in which a refrigeration circuit is constructed by connecting a compressor, an air-cooled condenser, a liquid receiver, an expansion valve, and an evaporator in this order, the air-cooled condenser can be connected to a plurality of air-cooled condensers. a circuit in which a switching valve is inserted between the switching valves and the refrigerant is sequentially passed through the plurality of air-cooled condensers to the liquid receiver; The present invention is industrially advantageous because an energy-saving refrigeration system is obtained by providing a circuit for flowing the remaining liquid through an air-cooled condenser after introducing it into the receiver, and switching the switching valve according to the outside temperature. It is extremely useful.

[Brief explanation of the drawing]

1 and 2 are refrigerant flow diagrams in a known refrigeration system, FIG. 3 is a refrigerant flow diagram according to the present invention, and FIG.
A Mollier diagram comparing the refrigeration cycle shown in the figure with that of FIG. 2, and FIGS. 5 to 10 are flow diagrams showing combinations of various switching valves for switching the condenser shown in FIG. 3, respectively. 11... Compressor, 12... First condenser, 13...
...Second condenser, 14...Liquid receiver, 15...Expansion valve, 16...Evaporator, 17...Four-way valve, 21,2
2, 23, 24... Solenoid valve, 31, 32... Check valve, 41, 42... 3-way valve.

Claims (1)

[Scope of utility model registration request] In a refrigeration system configured by connecting a compressor, an air-cooled condenser, a liquid receiver, an expansion valve, and an evaporator in this order to form a refrigeration circuit, the air-cooled condenser is divided into a plurality of parts,
a circuit in which a switching valve is inserted between the switching valves and the refrigerant is sequentially passed through the plurality of air-cooled condensers to the liquid receiver; A refrigeration system characterized in that a circuit is provided in which the remaining air flows through an air-cooled condenser after being introduced into the air, and the switching valve is switched in accordance with outside air temperature.