Abstract:
A environmental control system (ECS) for an aircraft includes a primary heat exchanger configured to receive bleed air from a turbine compressor of the aircraft and a secondary heat exchanger having an input configured to receive a flow from the primary heat exchanger and a secondary heat exchanger output. The ECS also includes a thermoelectric condensing device having an input in fluid communication with the output of the secondary heat exchanger and also having a thermoelectric condensing device output.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present disclosure relates to an air conditioning system for an aircraft and, in particular, to using a thermoelectric device to regulate the air used to regulate temperature in an aircraft. 
         [0002]    Conventional aircraft environmental control systems (ECSs) incorporate an air cycle machine, also referred to as an air cycle cooling machine, for use in cooling and dehumidifying air for an aircraft cabin. The air cycle machine may receive bleed air from a compressor that may have been passed through a primary heat exchanger (PEX). 
         [0003]    In more detail, on aircraft powered by turbine engines, the air to be conditioned in the air cycle machine is typically air bled from one or more of compressor stages of the turbine engine. In conventional systems, this bleed air passes through the air cycle machine compressor where it is further compressed. The compressed air is passed through a heat exchanger (condenser) to cool the compressed air sufficiently to remove moisture and dehumidify the air. The dehumidified compressed air is expanded in a first turbine of the air cycle machine to both extract energy from the compressed air so as to drive the shaft and also to cool the expanded turbine exhaust air before it is supplied to the aircraft cabin as conditioned cooling air. The cooled expanded air serves as the cooling cross-flow in the condenser and is then may be further expanded in a second turbine before being provided to aircraft cabin. 
       SUMMARY OF THE INVENTION 
       [0004]    According to one embodiment, an environmental control system (ECS) for an aircraft is disclosed. The ECS includes a primary heat exchanger configured to receive bleed air from a turbine compressor of the aircraft and a secondary heat exchanger having an input configured to receive a flow from the primary heat exchanger and a secondary heat exchanger output. The ECS further includes a thermoelectric condensing device having an input in fluid communication with the output of the secondary heat exchanger and also having a thermoelectric condensing device output. 
         [0005]    Also disclosed is an aircraft that includes an aircraft cabin and turbine that includes a turbine compressor and an environmental control system (ECS). The ECS includes: a primary heat exchanger that receives bleed air from the compressor of the aircraft, a secondary heat exchanger having an input configured to receive a flow from the primary heat exchanger and a secondary heat exchanger output; and a thermoelectric condensing device having an input in fluid communication with the output of the secondary heat exchanger and also having a thermoelectric condensing device output. 
         [0006]    In another embodiment, a environmental control system (ECS) for an aircraft is disclosed. The ECS of this embodiment includes an air cycle machine that includes a turbine and a compressor and a thermoelectric condensing device that is in fluid communication with an output of the compressor and an input of the turbine. 
         [0007]    Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein. For a better understanding of the disclosure with the advantages and the features, refer to the description and to the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0009]      FIG. 1  shows a high level block diagram an environmental control system (ECS) that includes an air cycle machine (ACM) according to the prior art. 
           [0010]      FIG. 2  shows an example of an ECS that includes a thermoelectric condensing device that may be utilized in one embodiment; and 
           [0011]      FIG. 3  shows another example of an ECS that includes a thermoelectric condensing device that may be utilized in one embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0012]      FIG. 1  shows a high level block diagram an ECS  100  that includes an air cycle ACM  102  according to the prior art. Hot air from a compressor is received at a primary heat exchanger (PHX)  104 . The air is cooled in the PHX  104  by cross-flow from a ram air fan in some cases. After being cooled the air is provided to the ACM  102  and compressed by compressor  106 . For example, on a hot day at sea level the compressor  106  causes the air pressure to be increased which, in turn, heats the air. The heated air enters a secondary heat exchanger (SHX)  108 . Again, the SHX may cool the air my providing a flow across the input flow from a ram air fan. In the following, the input flow will refer to air that has passed through the PHX and the compressor  106 . The cooled air is then passed through a condenser  110  that causes water vapor in the input flow to condense into water droplets and be removed through a separator  112 . The water extracted by the separator  112  may be simply dumped overboard or may be sprayed into the ram-air intakes where the PHX  104  and SHX  108  are located to improve their cooling efficiency. 
         [0013]    A first turbine  114  receives the de-humidified air and allows it to expand. The expansion both further cools the air and provides for rotation of the shaft (not shown) to which the compressor  106 , the first turbine  114  and the second turbine  116  are all attached. The cooled air then is crossflowed back across the condenser  110  and to provide for cooling the condenser  110 . Finally, the air may be further expanded in the second turbine  116  and then provided into the cabin. In  FIG. 1 , various example parameters of the input flow at various stages are shown by way of example. These values are not limiting but are examples and are incorporated into this specification as is set forth explicitly herein. 
         [0014]    Embodiments herein allow for the removal of at least the first turbine  114  and the condenser  110 . This may be accomplished by providing a thermoelectric condenser downstream of the SHX  108 . The condenser includes a thermoelectric (TE) device. In one embodiment, the TE device is superlattice device. The TE device, when powered, “pumps” heat from the input flow to a location where the heat may be removed by, for example, a ram air flow and provides that heat to the ram air. 
         [0015]      FIG. 2  shows an example of an ECS  200  that includes a thermoelectric condensing device (TECD)  202  that may be utilized in one embodiment. In  FIG. 2 , various example parameters of the input flow at various stages are shown by way of example. These values are not limiting but are examples and are incorporated into this specification as is set forth explicitly herein. 
         [0016]    The ECS  200  includes an ACM  204 . In this embodiment, the ACM  204  includes a compressor  206  and a turbine  208  connected to co-resident on a shaft  210 . It shall be understood that expansion of a flow in the turbine  208  may provide rotational energy to drive the compressor  206  in one embodiment. 
         [0017]    An incoming flow from a turbine (e.g., jet engine) may be passed through a PHX  220 . Ram air (shown by arrows  240 ) may cool the received flow in a known manner. That same ram air may also be used to cool flows received by the SHX  230  and the TECD  202 . As such, all are shown as being included in ram air channel as generally indicated by dashed boxes  250 . It shall be understood that the exact orientation and arrangement of the PHX  220 , the SHX  230  and the TECD  202  may be varied from that shown in  FIG. 2 . For instance, the SHX  230  and the TECD  202  could be in series or parallel and the PHX could be in front or behind either or both the SHX  230  and the TECD  202 . 
         [0018]    The air leaving the PHX  240  is compressed by compressor  206  and provided to the SHX where it is cooled. That air is then further cooled by the TECD  202 . The heat is pumped from the flow where it is carried away by the ram air  240  due to application electrical power  260  to the TECD  202 . Removal of the heat by the TECD  202  may cause the vapor in the flow to become liquid water droplets. The liquid water droplets are removed from the flow by cyclone  262 . The dehumidified flow may then be expanded in turbine  208  of the ACM  204 . If need, a bypass line  250  may be provided between the output of the PHX  240  to control the temperature of the flow before it is provided to the cabin and that bypass line  250  is controlled by a valve  260 . 
         [0019]    From time to time herein, an element may be described as being located in a fluid path between two elements. For example, the water cyclone  262  is fluid communication with the TECD  202  and the turbine  208  and is disposed in a fluid path between them. 
         [0020]    In this version, the ram cooled TECD may allow for the omission of the first turbine  114  of  FIG. 1 . In addition, it may allow for the reduction of the ACM  240  outlet temperature to drop by up to 60%. In the illustrated example, the TECD  202  may cool the air at 2250 BTU/min (39 kW). 
         [0021]    According to another embodiment, the ACM  204  may be eliminated in whole or in part. For instance, in  FIG. 3 , the ECS  300  includes a thermoelectric condensing device (TECD)  302  that may be utilized in one embodiment. In  FIG. 3 , various example parameters of the input flow at various stages are shown by way of example. These values are not limiting but are examples and are incorporated into this specification as is set forth explicitly herein. 
         [0022]    An incoming flow from a compressor (e.g., jet engine) may be passed through a PHX  320 . Ram air (shown by arrows  340 ) may cool the received flow in a known manner. That same ram air may also be used to cool flows received by the SHX  330  and the TECD  302 . As such, all are shown as being included in ram air channel as generally indicated by dashed boxes  350 . It shall be understood that the exact orientation and arrangement of the PHX  320 , the SHX  330  and the TECD  302  may be varied from that shown in  FIG. 3 . For instance, the SHX  330  and the TECD  302  could be in series or parallel and the PHX could be in front or behind either or both the SHX  330  and the TECD  302 . 
         [0023]    The air leaving the PHX  340  provided to the SHX where it is cooled. That air is then further cooled by the TECD  302 . The heat is pumped from the flow where it is carried away by the ram air  340  due to application electrical power  360  to the TECD  202 . Removal of the heat by the TECD  202  may cause the vapor in the flow to become droplets. The mist is removed from the flow by cyclone  362 . If need, a bypass line  350  may be provided between the output of the PHX  240  to control the temperature of the flow before it is provided to the cabin and that bypass line  350  is controlled by a valve  360 . 
         [0024]    In this version, the ram cooled TECD may allow for the omission of the first and second turbines  114 ,  116  of  FIG. 1 . In addition, in some instances, the compressor may also be omitted leading to an ECS that does not include an ACM. In the illustrated example, the TECD  302  may cool the air at 3530 BTU/min (62.2 kW). 
         [0025]    The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one more other features, integers, steps, operations, element components, and/or groups thereof. 
         [0026]    While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. 
         [0027]    Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.