JPS6117318Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is a two-stage air conditioner that can improve the effective energy ratio (E・E・R; ratio of refrigeration capacity to required power) while fully demonstrating dehumidification capacity. Regarding.

In the current situation where energy saving is desired, it is extremely desirable to improve the E/E/R of an air conditioner and reduce its running cost.

It is well recognized that in order to improve E・E・R, it is theoretically possible to operate with a high evaporation temperature (Te) and a low condensation temperature (Tc).

By the way, the cooling conditions in summer are when the outdoor temperature is 35℃ and the indoor air temperature is 27℃ and relative humidity is 50%.
(dew point temperature of 15.5℃). In this case, the evaporation temperature in the refrigeration equipment is required to be 27℃ or less, and the condensation temperature is required to be 35℃ or higher. has its own limits.

In actual operation, it is necessary to maintain a temperature difference between the indoor and outdoor heat exchangers with the above temperature conditions, and dehumidification is also required regarding the evaporation temperature (Te). Therefore, it is common that the condensation temperature (Tc) is approximately 50°C and the evaporation temperature (Te) is approximately 10°C, and E・E・R is further reduced.

In this way, in view of the fact that there is a limit to improving E・E・R with a single refrigerant system and no improvement can be expected, the present invention goes beyond such theoretical limits and further improves E・E・R.・This was done in an attempt to provide an air conditioner with a new system that can improve R.The specific contents of the device of the present invention will be explained in detail below with reference to device examples and characteristic diagrams shown in the attached drawings. do.

The air conditioner systemically illustrated in FIG. 1 has a two-stage structure and includes a first refrigeration circuit and a second refrigeration circuit.

The first refrigeration circuit includes a first compressor 1A and a first condenser 2.
A, the first expansion valve 3A and the first evaporator 4A are cyclically connected to form a known refrigeration cycle, and the second refrigeration circuit is connected in the same way to the second compressor 1B and the second condenser. The vessel 2B, the second expansion valve 3B, and the second evaporator 4B are cyclically connected.

The first evaporator 4A and the second evaporator 4B, which are arranged in parallel on the indoor side, are formed as an air-type heat exchanger, for example, a cross-fin type heat exchanger, and the first evaporator 4A and the second evaporator 4B are arranged in parallel on the indoor side. The evaporator 4A is placed on the upstream (windward) side, and the second evaporator 4B is placed on the downstream (leeward) side. After the indoor air flowing in from the suction port is primarily cooled by the first evaporator 4A, 2 evaporator 4B to produce cold air, which is then blown into the room from the outlet.

Note that the first and second compressors 1A and 1B are not limited to separate compressors, and in the case of a reciprocating multi-cylinder compressor, each cylinder can be used as the first and second compressors in one unit. In addition, even in the case of the rotary compressor 1, if it has a structure in which one unit has multiple cylinders, this can also be used.

On the other hand, the first and second condensers 2A and 2B are not limited to two installed in parallel, but may of course be of a shared circuit type.

Therefore, the first refrigeration circuit and the second refrigeration circuit are designed to have a specific relationship in mutual operating conditions, and the compressors 1A and 1B and the condensers 2A and 2
B. By appropriately selecting the capacities of the expansion valves 3A, 3B and the evaporators 4A, 4B, the first evaporator 4A
The second evaporator 4A is preferably operated at a higher evaporation temperature than the second evaporator 4B, preferably the former 4A is operated at an evaporation temperature higher than the dew point temperature of the indoor air, and the latter 4B is operated at an evaporation temperature lower than the dew point temperature. are doing.

The air conditioner is further provided with a heat exchanger 5 for supercooling in association with the first and second refrigeration circuits, and one refrigerant passage 5A is connected to the low-pressure refrigerant liquid pipe of the first refrigeration circuit, i.e. It is interposed in the flow path of the low-pressure refrigerant liquid before passing through the first expansion valve 3A and flowing into the first evaporator 4A, and the other refrigerant path 5B is inserted into the high-pressure refrigerant liquid pipe of the second refrigeration circuit. 2 condenser 2B
The heat exchanger 5 is installed in the flow path of the high-pressure refrigerant liquid before passing through and flowing into the second expansion valve 3B, and the heat exchanger 5 exchanges heat between the low-pressure refrigerant and the high-pressure refrigerant liquid in the first and second refrigeration circuits. It is structured in such a way that it can be done.

Next, the operating mode of the above device will be explained below with reference to FIGS. 1 to 5.

In the first refrigeration circuit, the refrigerant gas sucked into the first compressor 1A is compressed to become a high-pressure gas, condensed in the first condenser 2A to become a high-pressure liquid, and then decompressed and expanded in the first expansion valve 3A. The liquid becomes a low-pressure liquid, flows into the passage 5A of the heat exchanger 5, absorbs heat from the high-pressure liquid in the passage 5B, becomes dry, and reaches the first evaporator 4A.

On the other hand, in the second refrigeration circuit, the second compressor 1B
The refrigerant gas I' sucked in is compressed and becomes a high-pressure gas lo', and after being condensed in the second condenser 2B and becoming a high-pressure liquid, it flows into the passage 5B of the heat exchanger 5, where it is compressed by the low-pressure liquid in the passage 5A. The cooled and supercooled liquid
This leads to the second evaporator 4B.

In this operating state, the enthalpy (i ₄ ″−i ₄ ) and (i ₄
-i ₄ ') is heat exchanged, and the refrigeration capacity of the first refrigeration circuit side, which has a higher evaporation temperature than the two-stage operation method that does not use the heat exchanger 5, is as shown in Figure 2. decreases from G ₁ × (i ₁ − i ₄ ) to G ₁ (i ₁ − i ₄ ″),
On the other hand, the refrigeration capacity on the second refrigeration circuit side is G ₂ (i ₁ ′−
i ₄ ) to G ₂ (i′ ₁ −i′ ₄ ).

However, G ₁ and G ₂ are the refrigerant circulation amounts in the first and second refrigeration circuits, respectively.

From the above, it can be seen that under conditions where the evaporation temperatures Te ₁ and Te ₂ do not change, the two-stage cycle without the heat exchanger 5 can achieve the same refrigerating capacity [G ₁ × in Te ₁ ]
(i ₁ −i″ ₄ ), and in Te ₂ , G ₂ ×(i′ ₁ −i′ ₄ )], it is found that it is necessary to decrease G ₁ and increase G ₂ .

Therefore, the input at the compressor is G ₁ × (i ₂ − i ₁ ) + G ₂
×(i′ ₂ −i′ ₁ ), so since G ₂ increases in the second refrigeration circuit, which requires a lot of power,
E・E・R gets worse.

The above explanation is based on the evaporation temperature Te ₁ of the first evaporator 4A.
This is the case where the evaporation temperature Te ₂ of the second evaporator 4B is kept unchanged in both comparison devices with and without the heat exchanger 5, that is, the sensible heat ratio (SHF) representing the dehumidification ability is changed. In this case, each E.
E and R are as shown in FIG.

To explain the case of Te ₁ = 21°C in Fig. 3, the condensation temperature (Tc) = 43°C, supercooling 5°C, or T ₃
(See Figure 2) = 38℃, SHF = 0.65, indoor air temperature
27℃, relative humidity 50%, outdoor temperature 35℃, superheat degree 7.5
In the general case where the temperature is ℃, (a) a two-stage cycle equipped with a heat exchanger 5;

According to the i-x air diagram, Te ₂ = 7.3℃, T′ ₃ = 22.0℃, i ₁ = 152.0kcal/Kg, i ₂ = 155.4kcal/Kg i ₃ = 111.2kcal/Kg, i′ ₃ = 106.2 kcal/Kg i″ ₄ can be obtained from the following formula.

i″ ₄ −i ₄ = i″ ₄ −i ₃ = G ₂ /G ₁ (i ₃ − i′ ₃ ), i.e., i″ ₄ = G ₂ /G ₁ (i ₃ − i′ ₃ ) + i ₃ where Regarding G ₂ /G ₁ , in order to make SHF=0.65, it is necessary to set G ₂ /G ₁ =2.68.

∴ i″ ₄ = 125.4kcal/Kg Also, i′ ₁ = 150.9kcal/Kg, i′ ₂ = 156.9kcal/Kg On the other hand, E・E・R is expressed by the following formula.

E・E・R=0.86×G ₁ (i ₁ −i″ ₄ )+G ₂ (i′ ₁ −i′ ₃ )/G ₁ (i ₂ −i ₁ )+G ₂ (i′ ₂ −i
' ₁ ) = 0.86 x (i ₁ - i'' ₄ ) + G ₂ /G ₁ (i' ₁ - i' ₃ ) / (i ₂ - i ₁ ) + G ₂ /G ₁ (i' _2
-i'1 ) =0.86×(152.0-125.4)+2.68(150.9-106.2)/(155.4-15
2.0) + 2.68 (156.9 - 150.9) ≒ 6.46 (b) Two-stage cycle without heat exchanger 5.

In order to obtain SHF=0.65, both Te ₁ and Te ₂ are equivalent to the device of the present invention having a heat exchanger 5.

However, G ₂ /G ₁ is different and becomes 4.37. i.e. relatively
G ₂ becomes larger. Therefore, E・E・R=0.86×G ₁ ×(i ₁ −i ₃ )+G ₂ (i′ ₁ −i ₃ )/G ₁ ×(i ₂ −i ₁ )+G ₂ (i′ ₂ −i
' ₁ ) =0.86×(152.0-111.2)+4.37(150.9-111.2)/(155.4-15
2.0) + 4.37 (156.9 - 150.9) ≒ 6.22 As is clear from the above comparison, the two-stage cycle without the heat exchanger 5 can also improve E・E・R, but this Approximately 4% more for devised devices
It is hoped that improvements will be made.

Next, the case of the present invention in which a heat exchanger 5 for supercooling is added without changing the capacity of refrigeration equipment such as a compressor, condenser, and evaporator will be explained using the psychrometric diagram shown in Fig. 4. In this case, the refrigeration capacity on the first refrigeration circuit side decreases and the refrigeration capacity on the second refrigeration circuit side increases, so the evaporation temperature (Te ₁ ) becomes higher (Te′ ₁ ) and the evaporation temperature (Te ₂ ) changes to a lower (Te′ ₂ ) and becomes balanced.

Therefore, as for the input to the compressor, (Te' ₁ ) increases, which is advantageous, but (Te' ₂ ) decreases, which is disadvantageous, and the overall refrigerating capacity does not change significantly.

From this, E・E・R hardly changes, but since the state point of the blown air becomes lower in both temperature and humidity, the sensible heat ratio (SHF), which indicates the dehumidification ability, decreases, which has the advantage of increasing the dehumidification ability. be.

In order to support this basis, examples showing substantial effects are shown in Figure 5 (a) and (b). It clearly shows that the two-stage refrigeration system (shown by the solid line) is improved over the two-stage refrigeration system (shown by the one-dot chain line) that does not have the heat exchanger 5.

Next, Figure 6 shows an example of the device of the present invention that is capable of both cooling and heating operations, and is equipped with a first refrigeration circuit and a second refrigeration circuit. The exchanger 4A is arranged on the windward side with respect to the indoor heat exchanger 4B, which also acts as an evaporator, in the second refrigeration circuit, and the refrigerant in the first refrigeration circuit and the refrigerant in the second refrigeration circuit are The basic structure of the heat exchanger 5 provided therein for heat exchange is the same as that shown in FIG. 1, and has exactly the same effect regarding the cooling cycle.

However, in order to enable both cooling and heating operations, each refrigeration circuit is equipped with a first cooling expansion valve 3A, a first heating expansion valve 6A, and a first four-way switching valve 7A. , a second cooling expansion valve 3B, a second heating expansion valve 6B, and a second four-way switching valve 7B are additionally provided, and both four-way switching valves 7A and 7B are switched in conjunction with each other. , the refrigerant flows as shown by the solid line arrow in the case of cooling operation, and as shown by the broken line arrow in the case of heating operation.

This device is characterized by the arrangement form of the heat exchanger 5, and on the other hand, the refrigerant passage 5A is
Cooling expansion valve 3A outlet and first indoor heat exchanger 4A
The other refrigerant passage 5 is interposed in the liquid pipe connecting the
B is interposed in a liquid pipe connecting the inlet of the second cooling expansion valve 3B and the inlet of the second heating expansion valve 6B.

With this connection, the refrigerant passage 5A and the refrigerant passage 5B become a low-pressure refrigerant passage and a high-pressure refrigerant passage during the cooling cycle, and the heat exchanger 5 functions as a subcooling heat exchanger. During the heating cycle, the heat exchanger 5 serves as a high-pressure refrigerant flow path, and the heat exchanger 5 substantially does not perform any heat exchange action. This clearly shows that the results do not affect the refrigeration cycle in any way.

In the case of this heating operation, since the first and second outdoor heat exchangers 2A and 2B operate at the same evaporation temperature, it is clear that there is no need to make the heat exchanger 5 function as in the case of cooling. Therefore, it is recognized that the arrangement of the heat exchanger 5 described above is one that satisfies the purpose.

As mentioned above, the device of the present invention includes a first compressor 1A, a second condenser 2A, a first expansion valve 3A, and an air-type first
First refrigeration circuit consisting of evaporator 4A, second compressor 1
B, a second refrigeration circuit consisting of a second condenser 2B, a second expansion valve 3B, and a second air-type evaporator 4B,
The first evaporator 4 is based on the flow direction of the indoor air flow.
A is disposed on the upstream side and a second evaporator 4B is disposed on the downstream side, and the first refrigeration circuit is operated at an evaporation temperature higher than the evaporation temperature of the second refrigeration circuit. The heat exchanger 5 is configured to perform heat exchange between the low-pressure refrigerant after passing through the first expansion valve 3A of the circuit and the high-pressure refrigerant after passing through the second condenser 2B of the second refrigeration circuit. 1. Since it is configured in conjunction with the second refrigeration circuit, conventional single-system evaporators are operated by maintaining a large temperature difference between indoor air temperature and evaporation temperature to ensure cooling capacity. In this type of air conditioner, it is possible to further improve the E・E・R values, which were considered to be the limits.

Furthermore, by operating the first evaporator 4A at an evaporation temperature higher than the dew point temperature of indoor air and the second evaporator 4B at an evaporation temperature lower than the dew point temperature,
In addition to the sensible heat change, the latent heat change can also be used, which further improves the efficiency, and since the supercooling heat exchanger 5 is provided, there is an advantage that the dehumidification capacity is increased.

[Brief explanation of the drawing]

FIG. 1 is a refrigeration circuit diagram according to an example of the device of the present invention,
Figures 2 to 4 and Figures 5A and 5B are explanatory diagrams of the operating characteristics of the device of the present invention; Figure 2 is a Mollier diagram;
The figure shows the evaporation temperature - E, E, R relationship diagram, Figure 4 is the air line diagram, Figure 5 A is the outside air temperature - E, E, R relationship diagram, and Figure 5 B is the outside air temperature - SHF relationship diagram. Figure, 6th
The figure is a refrigeration circuit diagram according to an example of the device of the present invention. 1A...First compressor, 1B...Second compressor, 2
A...first condenser, 2B...second condenser, 3A...
...first expansion valve, 3B...second expansion valve, 4A...first evaporator, 4B...second evaporator, 5...heat exchanger.

Claims (1)

[Claims for Utility Model Registration] 1. A first refrigeration circuit consisting of a first compressor 1A, a first condenser 2A, a first expansion valve 3A, and an air-type first evaporator 4A; 2 condenser 2
B, second expansion valve 3B, second air-type evaporator 4
The first evaporator 4A is disposed on the upstream side and the second evaporator 4B is disposed on the downstream side with respect to the flow direction of the indoor air flow. The low-pressure refrigerant after passing through the first expansion valve 3A of the first refrigeration circuit and the second condenser of the second refrigeration circuit A two-stage air conditioner characterized in that a heat exchanger 5 for exchanging heat with the high-pressure refrigerant after passing through the refrigerant 2B is provided in association with the first and second refrigeration circuits. 2. The first evaporator 4A is operated at an evaporation temperature higher than the dew point temperature of indoor air, and the second evaporator 4B is operated at an evaporation temperature lower than the dew point temperature. The two-stage air conditioner according to item 1.