JP2006078092A - Air cycle air conditioning system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air cycle air conditioning system capable of improving freezing capability by raising the expansion ratio of an expansion turbine while preventing icing of drain. <P>SOLUTION: This system comprises the expansion turbine 20 expanding air A in the atmosphere, a compressor 21 compressing and discharging low-temperature air A1 from the expansion turbine 20, a heat exchanger 22 performing heat exchange between the low-temperature air A1 and air-conditioning air A2, and an exhaust and supply passage 16 supplying a part EA1 of exhaust air EA from the compressor 21 to the expansion turbine 20. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an air conditioning system, and more particularly to an air cycle air conditioning system suitable for cooling a room such as a vehicle cabin.

In recent years, hydrocarbons and air are used as working fluids (refrigerants) in place of conventional chlorofluorocarbons in refrigerators that constitute air conditioning systems that cool indoors, such as vehicle cabins. In particular, since air can be easily taken from the atmosphere, a refrigerator using this air as a working fluid is often used in this type of air conditioning system. For example, in an air cycle air conditioning system having a refrigerator including a turbine, a compressor that compresses and discharges low-temperature air from the turbine, and a heat exchanger, ventilation from the room is performed with low-temperature air and heat using a heat exchanger. Some air conditioners are exchanged for indoor air conditioning, and water is sprayed on the heat exchanger to improve the refrigerating capacity (see, for example, Patent Document 1).
U.S. Pat. No. 4,015,438

  However, according to the air cycle air conditioning system according to Patent Document 1, since low-temperature air as a working fluid is obtained from air in the atmosphere, drainage is generated at the turbine outlet due to moisture contained in the air. To do. If the expansion ratio in the turbine is increased to improve the refrigeration capacity, the temperature at the turbine outlet decreases, so when the temperature of the outside air decreases, the drain freezes and forms between the turbine blades and the piping at the turbine outlet. Clogging occurs inside. If the above-mentioned phenomenon occurs during the operation of the air conditioning system, maintenance such as reduction of the freezing capacity of the freezer and removal of freezing is forced to reduce efficiency, and the coefficient of performance (COP) of the freezer is inferior. Smooth operation of the refrigerator, and hence smooth operation of the air conditioning system cannot be expected.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an air cycle air conditioning system that improves the refrigeration capacity and coefficient of performance of a refrigerator, and that can smoothly operate the refrigerator without icing drain.

  In order to achieve the above object, an air cycle air conditioning system according to the present invention includes an expansion turbine that expands air in the atmosphere, a compressor that compresses and discharges low-temperature air from the expansion turbine, and the low-temperature air. A heat exchanger that exchanges heat with air for air conditioning; and an exhaust supply passage that supplies part of the exhaust from the compressor to the expansion turbine.

  According to this configuration, since a part of the exhaust from the compressor that is higher than the temperature of the air in the atmosphere is supplied back to the expansion turbine, the air flowing into the turbine is mixed with the exhaust. The temperature rises. For this reason, even if the expansion ratio of the expansion turbine is increased to improve the refrigeration capacity, the air at the outlet of the expansion turbine can be adjusted so as not to be 0 ° C. or lower (below the freezing temperature). Can prevent the drain from freezing and clogging. On the other hand, the flow rate of the turbine is increased by the amount of exhaust gas mixed therein, and the refrigeration capacity (heat exchanger cooling capacity) is improved. In addition, since there is no freezing of the drain, maintenance such as removal of freezing is unnecessary, and operation efficiency is improved.

  In a preferred embodiment of the present invention, the heat exchanger further includes a drain supply passage that supplies at least a part of the drain generated from air-conditioning air to the expansion turbine.

  According to this configuration, at least a part of the drain generated from the air-conditioning air in the heat exchanger is added to the air in the atmosphere, which is the working fluid supplied to the expansion turbine, thereby increasing the specific heat and increasing the dew point. The refrigeration capacity can be increased.

  In a preferred embodiment of the present invention, there is further provided a ventilation supply passage for supplying at least a part of the ventilation air discharged from the air conditioning chamber into which the air conditioning air is introduced to the expansion turbine.

  According to this configuration, since the low-temperature ventilation air discharged from the air-conditioning room has a lower temperature than the air in the atmosphere (outside air), at least a part of this ventilation air is added to the air in the atmosphere. Thus, by effectively using the ventilation air, the turbine inlet temperature can be lowered to increase the mass flow rate, and the refrigeration capacity and the coefficient of performance of the refrigerator can be increased. In particular, even when the temperature is high, the mass flow rate of air to the expansion turbine is reduced, and the refrigeration capacity of the refrigerator is reduced, such as in summer, the supply of the ventilation air to the expansion turbine causes the turbine flow rate to decrease. Can be suppressed, and the refrigerating capacity can be kept high.

  According to the air cycle air conditioning system of the present invention, the refrigeration capacity can be improved by increasing the expansion ratio of the expansion turbine. Further, since the freezing of the drain can be suppressed, maintenance such as removal of freezing is unnecessary and the operation efficiency is improved.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a system diagram of an air cycle air conditioning system according to a first embodiment of the present invention. In the air cycle air conditioning system shown in the figure, the refrigerator R includes an expansion turbine 20 that expands air A in the atmosphere as a working fluid, and a compressor 21 that compresses and discharges the low-temperature air A1 from the expansion turbine 20. And a heat exchanger 22 for exchanging heat between the low-temperature air A1 and the air-conditioning air A2. The expansion turbine 20 and the compressor 21 are connected to and driven by the same rotating shaft 25 of a common driving machine 24 such as an electric motor.

  Air A in the atmosphere is supplied to the expansion turbine 20 constituting the refrigerator R through the inlet passage 11 and the intake passage 15. The low-temperature air A1 expanded to the low temperature by the expansion turbine 20 is introduced into the heat exchanger 22 through the refrigerant introduction passage 12 as a working fluid, and then introduced into the compressor 21 through the refrigerant discharge passage 13. After being compressed, the exhaust gas EA is discharged from the compressor 21 through the discharge passage 14 to the outside (in the atmosphere).

  On the other hand, air for air conditioning A2 is introduced from the atmosphere through the inlet 1 into the introduction passage 2 by the first blower fan F1 through a different route from the air A in the atmosphere as the working fluid. The air-conditioning air A2 is introduced into the heat exchanger 22 from the inlet 3 and is cooled to a low temperature by heat exchange with the low-temperature air A1, and then is taken out from the outlet 4 to the air-conditioning introduction passage 5 as the low-temperature air-conditioning air A3. Then, the vehicle is introduced from the entrance 7 through the passage 5 into the room 23 such as a vehicle cabin. Part or all of the drain DR generated from the air-conditioning air A <b> 3 by the heat exchanger 22 is introduced from the drain passage 6 into the suction passage 11.

  A part of the low-temperature air-conditioning air A3 that has air-conditioned the room 23 is sucked by the second blower fan F2 from the outlet 8, is discharged to the outside as the ventilation air VA through the ventilation passage 9, and the other part VA1. Is sucked from the outlet 8 by the third blower fan F3 and mixed into the air-conditioning air A2 in the introduction passage 2 through the reflux passage 10.

  Further, a part EA1 of the exhaust EA from the exhaust passage 14 is supplied to the inlet passage 11 through the exhaust supply passage 16, mixed into the air A, and introduced into the expansion turbine 20 from the intake passage 15. Yes.

Next, the operation of the above configuration will be described with a numerical example. The unit of numerical values is P (pressure) kPa, T (temperature) ° C, and G (mass flow rate) kg / s. The outside air temperature is slightly lower at 33 ° C and the relative humidity is 50%. Air (outside air) A (101.3P, 33.0T, 0.662G) in the atmosphere is sucked into the suction passage 11 and exhausted from the discharge passage 16. Part EA1 (101.3P, 113.3T, 0.074G) and drain DR (101.3P, 13.2T, 0.003G) from the drain passage 6 are mixed, and intake air (101.3P, 31.3T, 0.739G) And is sucked into the expansion turbine 20. Here, it expands to become low-temperature air A1, and is introduced into the heat exchanger 22 from the refrigerant introduction passage 12 (43.9P, 1.0T, 0.739G).
On the other hand, the air-conditioning air A2 (107.3P, 40.0T, 0.241G) introduced into the introduction passage 2 includes a part of the ventilation air VA1 (103.8P, 29.0T, O.973G) discharged from the room 23 Are joined through the reflux passage 10 and then introduced into the heat exchanger 22 from the inlet 3 (103.8P, 31.2T, 1.214G). The heat exchanger 22 exchanges heat between the low-temperature air A1 and the air-conditioning air A2, and the air-conditioning air A2 is air-conditioned as the low-temperature air-conditioning air A3 from the outlet 4 (101.3P, 13.2T, 1.214G). Enter the introduction passage 5.

The air-conditioning air A3 having a low temperature is supplied from the inlet 7 (101.3P, 16.3T, 1.211G) to the room 23. The air-conditioning air A3 is heated by the load (20.0 kW) in the room 23, and after passing through the outlet 8 (101.3P, 26.1T, 1.213G) of the room 23, a part of the ventilation passage 9 (101.3P) serves as a ventilation VA. , 26.1T, 0.240G). The other part VA1 is supplied to the introduction passage 2 through the reflux passage 10 as described above. In addition to the load (20.0 kW), sweat from the passenger (= water, 1.74 g / s) is also taken into consideration as the thermal element of the room 23, and the evaporated sweat generates the reflux passage 10 and the introduction passage 2. After that, the heat exchanger 22 becomes drain water, and the latent heat released at that time becomes a load on the heat exchanger 22.
On the other hand, the low-temperature air A1 introduced into the heat exchanger 22 from the refrigerant introduction passage 12 (43.9P, 1.0T, 0.739G) passes through the refrigerant outlet passage 13 (41.4P, 13.0T, 0.739G) after heat exchange. After being compressed by the compressor 21 and returned to normal pressure, most of the exhaust EA is discharged to the atmosphere via the discharge passage 14 (101.3P, 113.3T, 0.739G), and part EA1 is exhausted as described above. The air is mixed into the air A in the inlet passage 11 through the supply passage 16 (101.3P, 113.3T, 0.074G). The load of the electric motor used as the driving machine 24 is 36.8 kW, the refrigerating capacity of the heat exchanger 22 is 29.5 kW, and the coefficient of performance (COP) is 0.801.

  In this way, a part FA1 of the exhaust EA is supplied to the expansion turbine 20 via the exhaust supply passage 16, so that the temperature of the working fluid in the intake passage 15 becomes high even when the outside air temperature is low, It is possible to prevent the temperature of the working fluid at the outlet side of the expansion turbine 20, that is, the refrigerant introduction passage 12 from becoming below freezing point, thereby preventing the drainage generated from the working fluid from freezing. As a result, the expansion ratio of the expansion turbine 20 can be increased to improve the refrigeration capacity. Moreover, since it is only necessary to add the exhaust supply passage 16 that returns a part of the exhaust VE1 to the expansion turbine 20 side, an increase in the equipment cost of the air conditioning system can be suppressed. Further, since part of the drain DR generated from the air-conditioning air in the heat exchanger 22 is introduced into the working fluid of the expansion turbine 20 through the drain passage 6, the specific heat of the working fluid increases and the dew point increases. Therefore, the refrigerating capacity (cooling capacity of the heat exchanger 22) can be further improved.

  FIG. 2 is a system diagram of an air cycle air conditioning system according to the second embodiment of the present invention. This second embodiment is intended for summer when the temperature is high, and the outside temperature is slightly higher at 40 ° C. and the relative humidity is 34%. In the second embodiment, in particular, a ventilation supply passage for returning at least a part (all in this example) VA2 of the ventilation air VA from the ventilation passage 9 in the first embodiment to the suction passage 11 and joining the air A. 17 is provided, and first and second on-off valves 31 and 32 are provided in the passage 17 and the exhaust supply passage 16, respectively, and the on-off valves 31 and 32 are selectively opened and closed by a controller 33. That is, during operation, the second on-off valve 32 is closed in response to an external command 35, and a part of the ventilation air VA discharged from the air conditioning chamber 21 having a temperature lower than that of the outside air is VA2. By being added to A, the inlet temperature of the expansion turbine 20 can be lowered to increase the mass flow rate, and the refrigeration capacity and the coefficient of performance (COP) can be increased. When the other conditions except the outside air temperature are the same as in the first embodiment, the load of the electric motor used as the driving device 24 is 39.2 kW, the refrigeration capacity of the heat exchanger 22 is 30.9 kW, and the coefficient of performance (COP ) Is 0.788.

During the defrosting operation, the first on-off valve 31 is closed, the second on-off valve 32 is opened, and a part of the exhaust EA having a temperature higher than the outside air EA1 is added to the air A, thereby raising the inlet temperature of the expansion turbine 20. Then, the temperature of the low temperature air A1 from the expansion turbine 20 is increased to perform defrosting.
In the second embodiment of FIG. 2, the two on-off valves 31 and 32 are omitted, and both the high-temperature exhaust EA1 from the exhaust supply passage 16 and the low-temperature ventilation VA2 from the ventilation supply passage 17 are supplied to the suction passage 11. In that case, the flow rate of the working fluid entering the expansion turbine 20 is increased and the temperature rise is suppressed by appropriately setting the flow rate of the hot exhaust gas EA1 and the flow rate of the low temperature ventilation VA2. Thus, the refrigerating capacity can be improved.

  Further, in the first and second embodiments, the drain supply passage 6 can be omitted.

It is a distribution diagram showing an air cycle air-conditioning system of a 1st embodiment of the present invention. It is a systematic diagram which shows the air cycle air conditioning system of 2nd Embodiment of this invention.

Explanation of symbols

6 Drain supply passage 20 Expansion turbine 21 Compressor 22 Heat exchanger 23 Indoor (guest room)
16 Exhaust supply passage 17 Ventilation supply passage A Air A1 Low temperature air A2 Air conditioning air R Refrigerator EA Exhaust VA Ventilation air

Claims (3)

An expansion turbine for expanding air in the atmosphere;
A compressor for compressing and discharging low-temperature air from the expansion turbine;
A heat exchanger for exchanging heat between the low-temperature air and air-conditioning air;
An exhaust supply passage for supplying a part of the exhaust from the compressor to the expansion turbine;
Air cycle air conditioning system equipped with. 2. The air cycle air conditioning system according to claim 1, further comprising a drain supply passage that supplies at least a part of a drain generated from air-conditioning air to the expansion turbine in the heat exchanger. 3. The air cycle air conditioning system according to claim 1, further comprising a ventilation supply passage that supplies at least a part of the ventilation air discharged from the air conditioning chamber into which the air conditioning air is introduced to the expansion turbine.

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