Abstract:
An environmental control system including a turbomachine assembly having a shaft, motor, turbine and compressor, the compressor outputting a compressed air stream, a first valve that splits the compressed air stream into first and second compressed air streams, a heat exchanger to cool the first compressed air stream and output a cooled air stream, a second valve positioned to receive the cooled air stream and split the cooled air stream into first and second cooled air streams, wherein the first cooled stream is expanded in the turbine to produce an expanded air stream that is combined with the second compressed air stream and the second cooled air stream to provide a combined air stream having a temperature and a flow rate, and a controller that communicates control signals to the compressor, motor and first and second valves to control the temperature and flow rate of the combined air stream.

Description:
PRIORITY 
       [0001]    This application is a divisional of, and claims priority from, U.S. Ser. No. 13/343,059 filed on Jan. 4, 2012. 
     
    
     FIELD 
       [0002]    The present disclosure relates to environmental control systems and methods for aircraft with pressurized cabins and, more particularly, to aircraft environmental control systems and methods that utilize dedicated cabin air compressors to compress air. 
       BACKGROUND 
       [0003]    Bleed air, or compressed air obtained from within an aircraft&#39;s main engines, has traditionally been used to pressurize the aircraft cabin and cargo hold. However, the temperature of this compressed air is typically much higher than required and must be cooled prior to its injection into the cabin. Cooling bleed air in older aircraft required a vapor cycle refrigeration system, which was heavy, expensive and required excessive maintenance. More modern aircraft have eliminated the vapor cycle refrigeration by replacing it with an air cycle system. In addition to an air cycle system, a series of ducts, valves and other heavy equipment requiring intensive maintenance are required to operate this system. Thus, this system is also large, complex, not energy efficient, can overtax the main engine compressors, and results in poor fuel consumption by the aircraft. 
         [0004]    Current technological advances have overcome drawbacks presented by bleed air systems by utilizing dedicated separate cabin air compressors to provide compressed air to the aircraft cabin and cargo ventilation systems that is not sourced from the main engines of the aircraft. The pressurized air sourced from these dedicated cabin air compressors is matched to the required pressure so the system is able to operate with a more modest refrigeration system. When warmer air is needed, the compressors can be operated less efficiently to provide warmer air at the same pressure. However, this approach of using additional, large, high speed mechanical equipment, such as separate cabin air compressors, adds excess weight, reliability and complexity challenges to the aircraft. 
         [0005]    Given the benefits and drawbacks presented by both types of existing technology, there exists a need for an airplane environmental system that utilizes a single efficient, simple, lightweight, turbomachine that can be controlled to achieve the desired temperature and flow of air to the cabin without the need for additional mechanical equipment. 
       SUMMARY 
       [0006]    In one aspect, the disclosed environmental control system may include a turbomachine assembly having a shaft, a motor, a turbine and a compressor, the compressor outputting a compressed air stream, a first valve that splits the compressed air stream into first and second compressed air streams, a heat exchanger to cool the first compressed air stream and output a cooled air stream, a second valve positioned to receive the cooled air stream and split the cooled air stream into first and second cooled air streams, wherein the first cooled stream is expanded in the turbine to produce an expanded air stream that is combined with the second compressed air stream and the second cooled air stream to provide a combined air stream having a temperature and a flow rate, and a controller that communicates control signals to the compressor, the motor and the first and second valves to control the temperature and flow rate of the combined air stream. 
         [0007]    In another aspect, the disclosed environmental control system may include (1) a turbomachine assembly having a compressor, a motor and a turbine, wherein the compressor has a variable compressor geometry and is driven by a shaft to output a compressed air stream, wherein the motor is coupled to the shaft and has a variable motor power, and wherein the turbine is coupled to the shaft; (2) a first valve having a first variable splitting state to selectively divide the compressed air stream into a first compressed air stream and a second compressed air stream; (3) a heat exchanger positioned to cool the first compressed air stream and output a cooled air stream; (4) a second valve having a second variable splitting state to selectively divide the cooled air stream into a first cooled air stream and a second cooled air stream, wherein the first cooled air stream is coupled to the turbine such that the turbine expands the first cooled air stream as the first cooled air stream passes through the turbine, thereby producing an expanded air stream, and wherein the expanded air stream is combined with the second compressed air stream and the second cooled air stream to provide a combined air stream, the combined air stream having a temperature and a flow rate; and (5) a controller configured to control the temperature and the flow rate of the combined air stream by controlling, at least, the variable compressor geometry, the variable motor power, the first variable splitting state and the second variable splitting state. 
         [0008]    In yet another aspect, disclosed is an environmental control method. The method includes the steps of (1) providing a turbomachine assembly comprising a compressor, a motor and a turbine, wherein said compressor has a variable compressor geometry and is driven by a shaft, said motor and said turbine being coupled to said shaft, said motor being configured to selectively supply rotational power to said shaft; (2) obtaining an input air stream; (3) passing said input air stream through said compressor to obtain a compressed air stream; (4) providing a first valve configured to selectively split said compressed air stream into a first compressed air stream and a second compressed air stream; (5) cooling said first compressed air stream to obtain a cooled air stream; (6) providing a second valve configured to selectively split said cooled air stream into a first cooled air stream and a second cooled air stream; (7) passing said first cooled air stream though said turbine to obtain a turbine output stream, wherein said step of passing said first cooled air stream through said turbine supplies rotational power to said shaft; (8) combining said turbine output stream with said second cooled air stream and said second compressed air stream to obtain a combined air stream, said combined air stream having a temperature and a flow rate; and (9) controlling said compressor geometry, said motor, said first valve and said second valve to minimize a first difference between said temperature and a target temperature and a second difference between said flow rate and a target flow rate. 
         [0009]    Other aspects of the disclosed environmental control system and method will become apparent from the following detailed description, the accompanying drawings, and the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a schematic representation of a first embodiment of the disclosed aircraft environmental control system; 
           [0011]      FIG. 2  is a schematic representation of a second embodiment of the disclosed aircraft environmental control system; 
           [0012]      FIG. 3  is a schematic representation of a third embodiment of the disclosed aircraft environmental control system; and 
           [0013]      FIG. 4  is a flow chart depicting one aspect of the disclosed environmental control method. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    Referring to  FIG. 1 , a first embodiment of the disclosed aircraft environmental control system, generally designated  100 , may include a compressor  102 , a motor  104 , a turbine  106 , first and second valves  108 ,  110 , a heat exchanger  112 , temperature sensors  114 ,  116 ,  118 ,  120 , pressure sensors  122 ,  124 ,  126 , flow sensors  128 ,  130  and a controller  132 . Additional components, such as additional temperature, pressure and flow sensors, may be included as part of the disclosed aircraft environmental control system  100  without departing from the scope of the present disclosure. 
         [0015]    The compressor  102 , the motor  104  and the turbine  106  may be assembled as a turbomachine assembly  134 . Specifically, the compressor  102  may be driven by a shaft  136 , and both the motor  104  and the turbine  106  may supply rotational power to the shaft  136 . Therefore, the motor  104  may only be required to draw electrical power sufficient to make up the difference between the rotational power supplied by the turbine  106  and the desired amount of rotational power to be supplied to the compressor  102 . 
         [0016]    The compressor  102  may be a variable geometry air compressor. Therefore, the geometry of the compressor  102  may be actively controlled in response to control signals (communication line  138 ) received from the controller  132 . However, use of a fixed geometry compressor is also contemplated. 
         [0017]    The motor  104  may be an electric motor or the like, and may selectively supply rotational power to the shaft  136  to drive the compressor  102 . The amount of power supplied by the motor  104  to the shaft  136  may be controlled by the controller  132 , which may communicate control signals (communication line  140 ) to the motor  104 . 
         [0018]    The turbine  106  may be a fixed geometry turbine, and may supply rotational power to the shaft  136  to drive the compressor  102 . However, use of a variable geometry turbine is also contemplated. Those skilled in the art will appreciate that use of a variable geometry turbine may introduce another parameter (turbine geometry) that may be controlled by the controller  132  to achieve the desired output. 
         [0019]    The controller  132  may be any apparatus or system capable of generating control signals for controlling the compressor  102 , the motor  104 , the turbine  106 , and the first and second valves  108 ,  110  based on input signals received from the temperature sensors  114 ,  116 ,  118 ,  120 , the pressure sensors  122 ,  124 ,  126 , and the flow sensors  128 ,  130  to achieve a cabin air stream  176  having the desired temperature and flow rate. For example, the controller  132  may be a computer processor or the like that has been pre-programmed with one or more control algorithms configured to control the cabin air stream temperature and flow rate. 
         [0020]    An input air stream  150  may be supplied to the compressor  102 , where it may be compressed and output as a compressed air stream  152 . The input air stream  150  may come from a ram air duct. 
         [0021]    The input air stream  150  will be at a temperature and pressure. The pressure sensor  122  may sense the pressure of the input air stream  150 , and may communicate to the controller  132  a signal indicative of the pressure of the input air stream  150  by way of communication line  156 . The compressor  102  inlet temperature may be determined from the compressor inlet pressure sensed by pressure sensor  122  and airplane data typically available to the controller  132 . Alternatively, the compressor  102  inlet temperature may be measured directly by way of optional temperature sensor  114 , which may communicate to the controller  132  a signal indicative of the temperature of the input air stream  150  by way of communication line  154 . 
         [0022]    The temperature and pressure of the input air stream  150  depend on the source of the input air stream  150  and/or the ambient conditions. For example, when the aircraft is on a tarmac in a warm climate, the temperature and pressure of the input air stream  150  may be relatively higher than when the aircraft is moving at altitude. Therefore, the signals (communication lines  154 ,  156 ) received by the controller  132  may be used by the controller  132  to generate control signals. 
         [0023]    The compressed air stream  152  output by the compressor  102  may be at a temperature and pressure, which may be measured by temperature sensor  116  and pressure sensor  124 . The temperature sensor  116  may communicate to the controller  132  a signal indicative of the temperature of the compressed air stream  152  by way of communication line  158 . The pressure sensor  124  may communicate to the controller  132  a signal indicative of the pressure of the compressed air stream  152  by way of communication line  160 . 
         [0024]    The flow rate of the compressed air stream  152  output by the compressor  102  may be measured by the flow sensors  128 ,  130 . While a dedicated flow sensor is not shown on the compressed air stream  152 , those skilled in the art will appreciate that the flow rate of the compressed air stream  152  may be derived by totaling the flow rates measured by both flow sensor  128  and flow sensor  130 . The flow sensors  128 ,  130  may communicate to the controller  132  signals indicative of the measured flow rates by way of communication lines  162 ,  164 . 
         [0025]    The flow sensors  128 ,  130  may optionally include pressure and temperature information. For example, the flow sensors  128 ,  130  may be venturi or turbine flow sensors, which may require pressure and temperature information to obtain a reliable measurement. However, flow sensors that do not require pressure and temperature information, such as anemometer flow sensors, are also contemplated. 
         [0026]    Thus, the temperature, pressure and flow rate of the compressed air stream  152  may be dictated by, among other things, the geometry of the compressor  102  and the rotational power supplied to the compressor  102  by the shaft  136 , both of which may be controlled by the controller  132 . 
         [0027]    The compressed air stream  152  may be split at the first valve  108  into a heat exchanger stream  166  and a heat exchanger bypass stream  168 . The first valve  108  may be controlled by the controller  132  by way of communication line  170 . The control signal communicated by the controller  132  to the first valve  108  may control the split between the heat exchanger stream  166  and the heat exchanger bypass stream  168 . Therefore, the first valve  108  may control the division of the flow between the heat exchanger stream  166  and the heat exchanger bypass stream  168 . 
         [0028]    Optionally, the first valve  108  (or an additional valve unit) may also control the total impedance across the first valve  108 . Therefore, by controlling the impedance, the first valve  108  may control the flow rate downstream of the first valve  108 . 
         [0029]    The heat exchanger bypass stream  168  may bypass the heat exchanger  112 , and may be combined with the turbine output stream  172  and the turbine bypass stream  174  at combination point  180 . The combination of the heat exchanger bypass stream  168 , the turbine output stream  172  and the turbine bypass stream  174  may form the cabin air stream  176 , which may flow into the cabin  178 . 
         [0030]    The heat exchanger bypass stream  168  will have a temperature, a pressure and a flow rate. The temperature of the heat exchanger bypass stream  168  may be substantially the same as the temperature of the of the compressed air stream  152 , though additional temperature and pressure sensors (not shown) may be provided on the heat exchanger bypass stream  168  without departing from the scope of the present disclosure. The flow rate of the heat exchanger bypass stream  168  may be measured by flow sensor  130 . Flow sensor  130  may communicate to the controller  132  a signal indicative of the flow rate of the heat exchanger bypass stream  168  by way of communication line  164 . 
         [0031]    The heat exchanger stream  166  may pass through the heat exchanger  112 . The heat exchanger  112  may cool the heat exchanger stream  166  and may output a cooled stream  182 . The heat exchanger  112  may be any apparatus or system capable of cooling the heat exchanger stream  166 . For example, the heat exchanger  112  may be capable of cooling the heat exchanger stream  166  approximately to ambient conditions. 
         [0032]    The cooled stream  182  may exit the heat exchanger  112  at a temperature, pressure and flow rate, which may be measured by temperature sensor  118  and flow sensor  128 . The temperature sensor  118  may communicate to the controller  132  a signal indicative of the temperature of the cooled stream  182  by way of communication line  184 . The flow sensor  128  may communicate to the controller  132  a signal indicative of the flow rate of the cooled stream  182  by way of communication line  162 . The pressure of the cooled stream  182  may be substantially the same as the pressure of the compressed air stream  152 , though an additional pressure sensor (not shown) may be provided on the cooled stream  182  without departing from the scope of the present disclosure. 
         [0033]    Thus, the controller  132  may communicate control signals to the first valve  108  by way of communication line  170  to control the flow rates of the heat exchanger stream  166  and the heat exchanger bypass stream  168 . Additionally, the control signals communicated to the first valve  108  may control the split between the heat exchanger stream  166  and the heat exchanger bypass stream  168 , thereby controlling the amount (e.g., percentage) of the compressed air stream  152  that is cooled by the heat exchanger  112 . 
         [0034]    The cooled stream  182  may be supplied to the second valve  110 , which may split the cooled stream  182  into a turbine input stream  186  and the turbine bypass stream  174 . The second valve  110  may be controlled by the controller  132  by way of communication line  188 . The control signal communicated by the controller  132  to the second valve  110  may control the split between the turbine input stream  186  and the turbine bypass stream  174 . Therefore, the second valve  110  may control the flow rate downstream of the second valve, as well as the division of the flow between the turbine input stream  186  and the turbine bypass stream  174 . 
         [0035]    The turbine bypass stream  174  may bypass the turbine  106 , and may be combined with the turbine output stream  172  and the heat exchanger bypass stream  168  at combination point  180 . 
         [0036]    The turbine bypass stream  174  may have a temperature, which may be substantially the same as the temperature of the cooled stream  182 . However, additional temperature, pressure and flow sensors (not shown) may be provided on the turbine bypass stream  174  without departing from the scope of the present disclosure. 
         [0037]    The turbine input stream  186  may pass through the turbine  106 . The turbine  106  may expand the turbine input stream  186 , thereby outputting a cooled turbine output stream  172 . The energy extracted by the turbine  106  from the turbine input stream  186  is supplied to the shaft  136  to drive the compressor  102 . 
         [0038]    The turbine output stream  172  may be combined with the turbine bypass stream  174  and the heat exchanger bypass stream  168  at combination point  180  to form the cabin air stream  176 , which may be supplied to the cabin  178 . 
         [0039]    The cabin air stream  176  may enter the cabin  178  at a controlled temperature and flow rate. The temperature of the cabin air stream  176  may be measured by temperature sensor  120 , which may communicate to the controller  132  a signal indicative of the measured temperature by way of communication line  190 . The flow rate of the cabin air stream  176  may be derived from the total flow measured by both flow sensors  128 ,  130 , though a dedicated flow sensor (not shown) may be provided on the cabin air stream without departing from the scope of the present disclosure. 
         [0040]    Thus, the controller  132  may control both the temperature and the flow rate of the cabin air stream  176 . Specifically, the controller  132  may generate control signals and may communicate (by way of communication lines  138 ,  140 ,  170 ,  188 ) the control signals to the compressor  102 , the motor  104 , the first valve  108  and the second valve  110  based on input signals received (by way of communication lines  154 ,  156 ,  158 ,  160 ,  162 ,  164 ,  184 ,  190 ) from the temperature sensors  114 ,  116 ,  118 ,  120 , the pressure sensors  122 ,  124 ,  126 , and the flow sensors  128 ,  130 . The controller  132  may also ensure that the pressure of the cabin air stream  176  is greater than the pressure of the cabin  178  to ensure positive airflow into the cabin  178 . 
         [0041]    An outflow valve  194  may control the flow rate of the outflow stream  196  from the cabin  178 , thereby maintaining the desired pressure within the cabin  178 . A separate cabin pressure controller  193  may be provided to control the pressure in the cabin  178  by controlling the outflow valve  194  based on cabin pressure signals supplied to the controller  193  by the cabin pressure sensor  126 . Controlling the cabin pressure with only one controller is also contemplated. 
         [0042]    Referring to  FIG. 2 , a second embodiment of the disclosed aircraft environmental control system, generally designated  200 , may generally retain the architecture of the system  100  shown in  FIG. 1 , but may additionally include a recirculation stream  202 . A recirculation fan  204  may move air along the recirculation stream  202 . 
         [0043]    In one implementation of the second embodiment, the recirculation stream  202  draws air from the cabin  208 , and may combine the recirculation stream  202  with the turbine output stream  210 , the turbine bypass stream  212  and the heat exchanger bypass stream  214  at combination point  216  to form the cabin air stream  218 , which may be supplied to the cabin  208 . 
         [0044]    Other implementations, such as implementations in which the recirculation stream  202  is introduced at other points in the system  200  (i.e., at points other than combination point  216 ), are also contemplated. 
         [0045]      FIG. 3  illustrates a third embodiment of the disclosed aircraft environmental control system, generally designated  300 , which may generally retain the architecture illustrated in  FIG. 1 , but may additionally include a water extractor  302 . 
         [0046]    The water extractor  302  may receive the cooled stream  304  from the heat exchanger  306 , and may remove water vapor from the cooled stream  304 . Therefore, the output from the water extractor  302  may be a cooled dry stream  308 , which may be supplied to the second valve  310 . 
         [0047]    While the water extractor  302  is schematically shown as a box in the drawings, those skilled in the art will appreciate that the water extractor  302  may include a recirculation loop that passes through the turbine  312 , which optionally may be a variable geometry turbine. 
         [0048]    Referring to  FIG. 4 , also disclosed is a method  400  for controlling the temperature and flow rate of an air stream, such as a cabin air stream supplied to the cabin of an aircraft. As shown at block  402 , the method  400  may begin with the step of providing a turbomachine assembly. The turbomachine assembly may include a compressor, a motor and a turbine. The compressor may have a variable compressor geometry and may be driven by a shaft. The motor and the turbine may both be coupled to the shaft to supply rotational power to the shaft. 
         [0049]    As shown at block  404 , an input air stream may be obtained. Then, as shown at block  406 , the input air stream may be passed through the compressor to obtain a compressed air stream. 
         [0050]    A first valve may be provided, as shown at block  408 . The first valve may be controllable to selectively split the compressed air stream into a first compressed air stream and a second compressed air stream. As shown at block  410 , the first compressed air stream may be cooled, such as by passing the first compressed air stream through a heat exchanger, thereby providing a cooled air stream. 
         [0051]    A second valve may be provided, as shown at block  412 . The second valve may be controllable to selectively split the cooled air stream into a first cooled air stream and a second cooled air stream. As shown at block  414 , the first cooled air stream may be expanded and, thus further cooled, by passing the first cooled air stream through a turbine, thereby providing a turbine output stream. The step of passing the first cooled air stream through the turbine may supply rotational power to the shaft. 
         [0052]    As shown at block  416 , the turbine output stream may be combined with the second cooled air stream and the second compressed air stream to obtain a combined air stream. The combined air stream may have a temperature and a flow rate. 
         [0053]    As shown at block  418 , the compressor geometry, the motor (e.g., the motor power), the first valve (e.g., the splitting state of the first valve) and the second valve (e.g., the splitting state of the second valve) may be controlled to minimize both ( 1 ) a difference between the temperature of the combined air stream and a target temperature and ( 2 ) a difference between the flow rate of the combined air stream and a target flow rate. 
         [0054]    Accordingly, the disclosed environmental control systems and methods may be employed to control the temperature and flow rate of a cabin air stream using a single turbomachine by controlling, among other possible parameters, the compressor geometry, the motor power and the states of the valves. 
         [0055]    Although various aspects of the disclosed environmental control system and method have been shown and described, modifications may occur to those skilled in the art upon reading the specification. The present application includes such modifications and is limited only by the scope of the claims.