Air circulating air cooler

(54) Designation Plant for cooling an air circulation (56) Publications cited DE 2 QOf 826 (B6^JLD 13/08), FR 1 37'6 252 (b6Ad 13/08) (57) Summary:

The invention relates to temperature control in several zones in circulation air cooling systems. Specifically, in this system (10), the cab (115) and the cabin (120) are pressurized in an aircraft and cooled by supplying cooled air therewith. Trim valves (180, 205) set by a common actuator (195) regulate the mixture of uncooled inlet air of the plant and the cooled air for individual control of the temperatures in the cabin and the cab.

OB 603416

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The present invention relates to a turbine-driven cooling air circulation system with the purpose of supplying cool air under overpressure to several zones, such as the cab and cabin of a transport aircraft.

In a typical cooling system for air circulation or air circulation, which is used to create overpressure in aircraft cabinets and the like and to cool said cabinets, the inlet air of the plant (from a supply) obtained from, for example, a turbine engine compressor is pressurized in the refrigerator's air compressor, of ambient air 1 a heat exchanger and then fed to the plant's turbine where it is allowed to perform work, which causes the air to cool, after which the air is discharged to the aircraft cabin and the like. The turbine is mechanically coupled to the compressor, so work done by the compressed air with respect to the turbine helps to drive the compressor's rotor.

Sometimes pressurization and cooling of several zones need to be carried out by means of one and the same system for cooling air circulation, for example when one and the same system must pressurize and cool the cockpit and the cabin of a transport aircraft. So far, in air conditioning of several zones, it has been necessary to carry out temperature control of both the entire air flow blown out of its turbine and the part of the air flow that has been introduced into one of said zones. For temperature control of the remaining zone, the temperature control of the turbine's total exhaust air flow has generally been relied on. Such temperature control of the entire exhaust air stream of the turbine is usually achieved by simultaneously controlling the total amount of air flowing through the turbine (through the 1 series compressor) and regulating the amount of cold air mixed with the turbine exhaust air before transferring to the air-conditioned zones. In much the same way, regulation of the temperature of one controlled zone 1 is usually carried out by mixing in a controlled manner cold air with

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the part of the turbine's cooled exhaust air which is transferred to the zone in question.

It should be noted that the cooling of the second (unregulated) zone is dependent on the requirements that the regulated zone places on the cooling and on the regulation of the temperature of the main exhaust air of the turbine. In modern transport aircraft, independent temperature control of two or more zones may be required. At first glance, it may appear that an obvious solution would be to carry out completely independent control in each zone of a mixture of cold air and cooled air discharged from the turbine of the air conditioner. However, such independent regulation would result in a significant duplication of plant parts (valves, controls, actuators and the like), whereby a significant increase in the cost, weight, complication rate and maintenance requirements of the plant would be obtained. Kan has therefore sought independent temperature control of several zones without using separate trim valves and actuators.

Thus, the present invention has for its object to provide independent temperature control in multiple zones cooled by a common air-conditioning system for circulating air that individual control means, trim valves and actuators are needed in each zone for the purpose.

In accordance with the invention, independent temperature control in two zones cooled by a common air conditioning system is achieved by providing each zone with a trim valve which regulates the amount of cold air mixed with cooled turbine air supplied to said zone, the trim valves being driven by a single actuator which is successively each valve opens from a closed position thereof while the remaining valve remains in the closed position. The actuator is operable depending on the temperature conditions in only one of the zones. Control valve means which regulate the temperature of the turbine's output: ps air flow in the plant as a whole is actuable depending on temperature conditions in the second zone. The operating mode of the actuator as above means that said actuator can adjust the trim valve in one zone, for example to achieve a lower temperature in said zone when required. When said trim valve is fully closed, an additional requirement for lower temperature in the zone in question will cause the actuator to continue to operate, thereby opening the trim valve assigned to the second zone so that the hot air flow to it increases. a tendency to raise the temperature in the latter zone. However, such a rise in temperature is prevented by the control valve means which further cools the total exhaust air from the turbine of the air conditioning system, thereby achieving the lower temperature desired in said one zone without disturbing the temperature maintained in the other zone. Thus, independent temperature control of the two zones is obtained by a single actuator for both trim valves assigned to the zones.

The invention will be described in detail below with reference to the accompanying drawings, in which Fig. 1 shows schematically the air circulation cooling system according to the present invention and Fig. 2 graphically shows the relationship between the setting of the trim valves used in the system according to Fig. 1 and the only operating actuator adjusting the valves. .

Fig. 1 generally shows the system for cooling circulating air according to the invention. The plant is supplied with air, for example with air discharged from the gas turbine engine compressor part, through the inlet conduit 15. The supplied air stream is divided at 20, whereby a portion of the supply air is passed through a primary heat exchanger (PHX) 25, in which the air is cooled by a stream of ambient air. , such as engine frame air, passed through the same. After discharge from the primary heat exchanger, in the latter cooled air, the compressor 50 of the plant is passed through the conduit 55, the control valve 40 and the conduit 45. The X compressor compresses the air, thereby causing it to be heated, after which the compressed air or compressed air is cooled in a second heat exchanger. (SHX) 50 by ambient air, for example the aforementioned engine frame air. As shown, the primary and secondary heat exchangers 25 and 50, respectively, may be located in a common housing, to which frame air is passed through the inlet 55. Upon discharge from the heat exchangers 25 and 5θ, the frame air is passed through the duct 60, at which end a fan 65 may be present.

8304553-4 with the purpose of ensuring that air flows continuously through the primary and secondary heat exchangers. As shown, the fan 75 can be operated simultaneously with the compressor 30 by means of the expansion air turbine 70 of the air conditioning system. A flow control valve 75 located in the fan outlet passage 80 can be used to control the flow of cooling air through the heat exchangers 25 and 50.

If desired, in order to remove water vapor from the exhaust air of the compressor, the latter air, after it has withdrawn from the secondary heat exchanger 50, can be fed through conduit 85 to condenser $ Q, from which the air is passed to the inlet to turbine 70 through conduit 95 . A drain 100, which may for example be disposed in conduit 95, provides a means for discharging condensed water from the condenser 9θ. The air supplied to the turbine performs work with respect to the turbine in the usual manner and thus causes its rotor to rotate. where: expansion and cooling of the air is carried out, whereupon the air is transferred from the turbine through the condenser 90 for cooling and drying of the turbine inlet air in the above manner. From the condenser, the turbine exhaust air is fed through conduits 105 and 110 to a first zone in the cab 115 to create an overpressure in said zone and to perform cooling there. Cabs, have an air outlet to a second zone or cabin 130 through an opening I25. Turbine exhaust air is supplied to cabin 130 directly through lines 105 and 112, line 112 being a continuation of line 105 downstream from the connection point between lines 105 and 110.

Part of the uncooled supply air is fed from the inlet conduit 15 through conduit 135 # valve 140 and conduit 145, 0 at the end of conduit 145, said inlet air is selectively added to the exhaust air from turbine 70. Valves 40 and 140 are actuated by actuator 150 which at the same time, both valves set to control the temperature of the air being discharged from the tub. In the preferred embodiment, the actuator 150 is operable in dependence on the control means 153, which in turn is actuated by a signal transmitted thereto by the turbine outlet temp. The sensor 154 in the channel 112. The sensor 15½ is shown for illustrative purposes in combination with the control means. rules Orga

8304553-4 also affects in response to a signal fed thereto by the cabin temperature sensor 155. A signal obtained from the control means 155 indicating an error between the signals from the sensors 154 and 155 causes the actuator IpO to close the valve 40 and to open the valve 140, which in practice, a partial shorting of the turbine exhaust air means that less cooling is needed in the cabin. To increase cooling in the cabin, actuator 150 opens valve 40 while closing valve 140 so as to obtain increased cooling by increasing the amount of air flowing through the turbine.

Ice formation in the turbine outlet can be reduced to a minimum by allowing the cabin air to be recirculated by means of fan 157 through filter 160 and check valve 165 in line 170.

In order for temperature control to be achieved in one zone, for example the driver's cab 115, uncooled inlet air to the plant is selectively mixed with the turbine outlet air supplied to the zone in question through conduit 110. This inlet air is fed to line 110 through line 175 and a first (cab) trim valve 180 located in line 185 communicating at its ends with lines 110 and 175, respectively, Valve 18o is actuated by actuator 155 Actuator 195 is actuated by actuator 196 which is actuable in response to signals transmitted thereto from the temperature sensors 197 and 200 in the channel 110 and in the cab respectively. Etc. errors between the signals from these sensors indicating that the cab's cooling should be reduced causes the actuator 195 to open the trim valve 18o further so that more uncooled supply air can be supplied to the channel 110. Similarly, signals emanating from the sensors 197 and 200 indicates that the cab must be cooled more to cause actuator 195 to partially close trim valve 180.

As mentioned above, it is often desired to provide both zones (the cab and cabin) with independent temperature control with the minimum possible duplication of the components. In accordance with the present invention, such independent control is achieved by means of a second (cabin) trim valve 205 disposed in conduit 175 and operated together with the trim valve.

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18θ by means of a common actuator 195 to regulate the amount of uncooled supply air supplied to conduits. 112 from

The relationship between the actuator 195 actuator area through the cab of trim cab Ιού and cab trim valve 20? is shown in Fig. 2. It is seen that the actuator 195 causes one of the trim valves to be opened successively while the other remains closed. Furthermore, it is seen that. If the cabin trim valve is fully open, the cab trim valve will be closed. When the actuation judgment is affected, the cab: trim valve will be closed successively while the cab's trim valve · is kept fully closed until the actuator strengthens. The cab trim valve completely closes, with both valves closed. Further operation of the actuator means that the cab of the cab can be opened successively while the cabin trim valve is completely closed.

The manner in which the cabin and driver cab valves, valves 40 and 140 for controlling the turbine exhaust air temperature and the associated actuators and sensors result in independent temperature control in both the cab and cabin without having to individually actuate the trim valves. This can best be realized with the aid of an example description of the plant's working methods. If it is assumed that the actuator is in the middle of its working position, ie open to half (50, both trim valves are closed. If the cab is too cold, the cab's trim valve 180 is opened so that more cold supply air can be fed into line 110 without disturbing the interior temperature of the cabin. On the other hand, if the cab is too hot and its trim valve is open, the trim valve will be closed gradually. If the cab is not sufficiently cooled when the latter trim valve is fully closed, the actuator will continue and thereby keep the cab of the cab closed while opening the cabin trim valve. Hereby, uncooled supply air is supplied to the cabin supply air which. in itself would warm the cabin. However, if the sensor 154 finds that the cabin supply air is heated, said sensor causes the control means 153 to actuate the actuator 15c, thereby controlling the setting of the valves 40 and 140 so as to

8304553-4 means that the temperature in the channel 105 is lowered, varies as the desired constant supply temperature to the cabin is maintained.

Although it is. particular embodiment of the invention has been shown, it will be apparent that alternative equivalent embodiments may be apparent to those skilled in the art. For example, while only two independent zones have been shown, it will be understood that additional zones may be provided within the scope of the invention. Furthermore, limits can be set for the sensors and / or actuators to prevent ice formation in the plant's turbine exhaust air. Thus, in the example given above, for example, the sensor Ό7 or the actuator 195 can be configured with suitable limits to prevent the turbine's exhaust air from being driven to below predetermined temperature when the sensor 137 controls the outlet air temperature in the manner described above. Likewise, the sensor 154 or the actuator 150 may have a suitable stop to prevent the temperature of the air-conditioning system's exhaust air from sinking below a predetermined temperature, thereby preventing ice formation when the sensor 154 requires increased cooling of the cabin.

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