Patent Publication Number: US-2015065023-A1

Title: Intercompressor bleed turbo compressor

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Application No. 61/872,912, filed on Sep. 3, 2013 which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     An environmental control system supplies pressurized air to any environment, such as a cabin and flight deck of an aircraft, for both comfort and pressurization. The air supplied by the environmental control system may originate from a compressor stage of an engine (e.g., via a bleed air system) and/or directly from exterior air (e.g., via a ram air system). The interaction of the environmental control system with the engine influences how much fuel is burnt by the engine. 
     For example, in a bleed air system of an aircraft, air is extracted from an engine core at different stage locations (e.g., a high pressure port and a low pressure port). The selection of the low pressure port is based on high altitude, hot day flight conditions, which results in a pressure from the engine on other day types and lower altitudes higher than required. When the air is at a higher pressure than required, the engine has a higher fuel burn than necessary. 
     BRIEF DESCRIPTION OF THE INVENTION 
     According to one embodiment, a turbo compressor is added to a low pressure port of a bleed system to provide a required pressure. 
     Additional features and advantages are realized through the techniques of the present invention. Other embodiments and aspects of the invention are described in detail herein and are considered a part of the claimed invention. For a better understanding of the invention with the advantages and the features, refer to the description and to the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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 forgoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a block diagram of a bleed system that includes a turbo compressor according to one embodiment; and 
         FIG. 2  is a schematic diagram of a turbo compressor of a bleed system according to one embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. 
     As indicated above, the selection of the low pressure port is based on hot day high altitude flight condition and results in unnecessary fuel by the engine. Thus, what is needed is a bleed inter-compressor that enables a bleed system to take advantage of a lower pressure port of an engine, while the aircraft is at the lower altitudes and/or flying in cooler temperatures, by boosting bleed-air above a final pressure before the bleed-air is passed onto an environmental control system. 
     In general, embodiments of the present invention disclosed herein may include a bleed system, comprising a high pressure circuit fluidly coupled a high pressure portion of an engine and configured to bleed a medium from the high pressure portion; a low pressure port fluidly coupled to a low pressure portion of the engine and configured to bleed the medium from the low pressure portion, wherein the medium includes a first set of properties when being bled by the low pressure port, the first set of properties comprising a pressure; and a bleed inter-compressor fluidly coupled to the low pressure port and configured to utilize a portion of the medium received from the low pressure port to increase the pressure. 
       FIG. 1  illustrates a bleed system  100 , which is an arrangement where a medium (e.g., air) is “bled” from at least one compressor stage of an engine. The bleed system  100  comprise a high pressure port  101 , a low pressure port  102 , a precooler  105 , and a turbo compressor  106  (e.g., an bleed inter-compressor), each of which are fluidly coupled via tubes, pipes, and the like, such that a medium is from the engine may be received at an initial flow rate, pressure, and temperature from either of the ports  101 ,  102  and provided as intermediate flow rate, pressure, and temperature. 
     An engine or engine core is a machine designed to convert energy into useful mechanical motion. Engine cores may utilize multiple stages to increase gains during the conversion of energy. Examples of an engine core include, but are not limited to, gas turbine, reciprocating, steam, jet, turbo-propeller, and pulse detonation engines. 
     The high pressure port  101  and the low pressure port  102  are access points to different compression stages of the engine. In general, the bleed system  100  bleeds the medium from the high pressure port  101  and/or the low pressure port  102  of an engine core in accordance with an operation state of a vehicle associated with the engine. In turn, because the bleed system  100  is in fluid communication with the environmental control system  110 , the medium is passed to the vehicle so that a constant environmental state of the vehicle is maintained through all operations states. 
     For example, on an aircraft, air is supplied to an environmental control system by being “bled” from a compressor stage of a gas turbine engine, upstream of a combustor. The temperature and pressure of this “bleed-air” varies widely depending upon which compressor stage and a revolutions per minute of the gas turbine engine. 
     That is, air may be bled from a high compression stage of a gas turbine engine when the operation state of the aircraft is landing or taxing (e.g., the engine is throttled down as less thrust is needed during these operation states). Further, air may be bled from a low compression stage of the gas turbine engine when the operation state of the aircraft is take-off or cruising at standard altitudes (e.g., the engine is throttled up as more thrust is needed during these operation states). By bleeding air from different compression stages of the gas turbine engine, a cabin pressure (e.g., environmental state) of the aircraft is efficiently maintained by the environmental control system at a target level regardless of the operation state. 
     As illustrated in  FIG. 1 , when bled (e.g., Arrow A) from the high pressure port  101 , the medium is passed through the precooler  105  to (e.g., Arrows B, E) the environmental control system  110 . That is, because the medium is of a high temperature (e.g., above 400° F.) when bled from the high pressure port  101 , the precooler  105  cools the medium, thereby lowing the temperature, to a suitable level for further processing by the environmental control system  110 . 
     Heat exchangers (e.g., a precooler  105 ) are equipment built for efficient heat transfer from one medium to another. Examples of heat exchangers include double pipe, shell and tube, plate, plate and shell, adiabatic wheel, plate fin, pillow plate, and fluid heat exchangers. Continuing with the aircraft example above, air forced by a fan (e.g., via push or pull methods) is blown across the heat exchanger at a variable cooling airflow to control the final air temperature of the bleed-air. 
     Further, when bled (e.g., Arrow C) from the low pressure port  102 , the medium is passed through the turbo compressor  106 . In turn, the turbo compressor  106  boosts the pressure of the medium as it exits the low pressure port  102 , so that the medium is received (e.g., Arrows D, E) at a suitable level for further processing by the environmental control system  110  (e.g., a higher pressure the initially bled from the low pressure port  102 ). Thus, the turbo compressor  106  may regulate a pressure of the medium (e.g., air) flowing before the medium is supplied to the environmental control system  110 . 
     A compressor (e.g., the turbo compressor  106  and/or the bleed inter-compressor) or fan is a mechanical device that pressurizes a medium (e.g., increasing the pressure of a gas by reducing its volume). Examples of a compressor include centrifugal, diagonal or mixed-flow, axial-flow, reciprocating, ionic liquid piston, rotary screw, rotary vane, scroll, diaphragm, air bubble compressors. Further, compressors are typically driven by an electric motor or a steam or a gas turbine. 
     An environmental control system (e.g., the environmental control system  110 ) of a vehicle, such as an aircraft or watercraft, provides air supply, thermal control, and cabin pressurization for a crew and passengers of the vehicle. The system may also include avionics cooling, smoke detection, and fire suppression. In  FIG. 1 , once the environmental control system  110  receives (e.g., Arrow E) the medium from bleed air system  100 , the bleed air is processed and supplied to the Outlet  1  at a final flow rate, pressure, and temperature (e.g., processed and supplied to the cabin of an aircraft at 14.6 psia). 
     The system of  FIG. 1  will now be described with reference to  FIG. 2 .  FIG. 2  is a schematic diagram of a turbo compressor  106  within a bleed system according to one embodiment.  FIG. 2  includes check valves  210 ,  211 , a flow valve  214 , and a compressor  220 , a turbine  222 , and a shaft  223 , e.g., which combine to form the turbo compressor  106 . The items of  FIG. 2  are connected via tubes, pipes, and the like, such that the medium is accepted the low pressure port  102  at the initial flow rate, pressure, and temperature and provided to the environmental control system  110  at the final flow rate, pressure, and temperature (e.g., from a first pressure to a second pressure that is higher than the first pressure). 
     For example, utilizing the aircraft example, properties of the bleed-air (e.g., the final flow rate, pressure, and temperature at the Outlet  1 ) enable the cabin of the aircraft to receive pressurized and cooled air during operation states that utilize the low compression stage (e.g., port  102 ) at a lower fuel cost due to the addition of turbo compressor (e.g., turbo compressor  106 ). 
     Valves, such as the check valves  210 ,  211  and the flow valve  214 , are devices that regulate, direct, and/or control a flow of a medium (e.g., gases, liquids, fluidized solids, or slurries, such as bleed-air) by opening, closing, or partially obstructing various passageways within the tubes, pipes, etc. of the cabin air conditioning system  200 . Valves may be operated by actuators such that the flow rates of any medium in any portion of the bleed system  100  may be regulated to a desired value. 
     In operation, the check valve  210  prevents reverse flow to the low pressure port  102 . The check valve  211  prevents recirculation of air to a compressor inlet. The flow value  214  supplies a portion of the medium to the turbine  222 . 
     The compressor  220  is a mechanical device that raises the pressure of the medium received from the check valve  210  (e.g., a pressure of the medium flowing from the low pressure location to the environmental control system). For instance, the compressor  220  is coupled to the low pressure port  102  of the bleed system  100  and configured to compress the medium received from the low pressure port  102  by the compressor  220  via the check valve  210 . 
     The turbine  222  is coupled to the compressor and configured to drive the compressor  220  via the shaft  223  to regulate the pressure of the medium. For instance, a portion of the medium is retrieved via the flow valve  214  (e.g., located upstream from the turbo compressor) and utilized by the turbine to drive the compressor  220 , after which the portion of the medium as an exhaust may be supplied to another component and/or system. That is, the fan stream, which includes the exhaust from the turbine  222 , may be supplied to a heat exchanger in communication with the turbine  222 . In the aircraft example, thrust may be recovered by dumping the exhaust, thereby reducing the need for ram air and increasing the fuel efficiency of the aircraft. 
       FIG. 2  will now be described in view of the aircraft example above. Bleeding air from a low pressure port  102  causes less of a fuel burn than bleeding air from a high pressure location. The compressor  220  is employed to ensure that the bleed-air is boosted above the final pressure before being passed onto the environmental control system  110  (e.g., thus, the first pressure of the bleed-air is regulated properly to the final pressure). To assist in further explanation of a pressure management by the compressor  220 ,  FIG. 2  includes demarcation points C1, D1, H that itemize properties of the bleed-air (e.g., the medium) at that point in the bleed system  100 . The properties include a change in flow-rate, a pressure, and a temperature. 
     In  FIG. 2 , the bleed-air is supplied from the low pressure port  102  through the check valve  210 , where before it arrives at the compressor  222  it includes a first flow-rate, a first pressure, and a first temperature (demarcation point C1). Then, before the bleed-air is passed to the compressor  222 , some of the flow rate is regulated by the flow valve  214  such that a portion of the bleed-air is supplied to the turbine  222  while the rest of the bleed-air goes through the compressor  222 . For example, the first flow rate is regulated by the flow valve  214  so that the turbine  222  is powered by a portion of the bleed-air at a second flow-rate, a second pressure, and a second temperature (demarcation point H). 
     When the turbine  222  receives the portion of the bleed-air regulated by the flow valve  214 , the turbine  222  drive the compressor  220  via the shaft  223  to pressurize the bleed-air based on the force applied from the shaft  223 . In this example, the resulting properties of the bleed-air after pressurization are a third flow-rate, a third pressure, and a third temperature (demarcation point D1), where the third pressure is greater than the first pressure. In addition, once the portion of the bleed-air that was supplied to the turbine  222  is utilized by the turbine  222 , that portion of the bleed-air proceeds to exit the turbine  222  (e.g., as indicated by Arrow J) and may proceed overboard or be utilized the aircraft (e.g., such as by entering the fan stream). Thus, the turbo compressor  106  enables, during the lower altitudes and/or the cooler temperatures, a pressure management method of providing the bleed-air by fluidly coupling the low pressure port  102  of the bleed system  100  to the compressor  220 , fluidly coupling an output of the compressor  220  to the environmental control system  110 , mechanically coupling the turbine  222  via the shaft  223  to the compressor  220 ; utilizing, by the turbine  222 , the portion of the medium to drive the compressor  220 ; and pressurizing, by the compressor  220 , the medium flowing from the low pressure port  102  to the environmental control system  100  from a first pressure (demarcation point C1) to a second pressure (demarcation point D1). 
     Aspects of the present invention are described herein with reference to flowchart illustrations, schematics, and/or block diagrams of methods, apparatus, and/or systems according to embodiments of the invention. Further, the descriptions of the various embodiments of the present invention have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to best explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein. 
     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. 
     The flow diagrams depicted herein are just one example. There may be many variations to this diagram or the steps (or operations) described therein without departing from the spirit of the invention. For instance, the steps may be performed in a differing order or steps may be added, deleted or modified. All of these variations are considered a part of the claimed invention. 
     While the preferred embodiment to the invention had been described, it will be understood that those skilled in the art, both now and in the future, may make various improvements and enhancements which fall within the scope of the claims which follow. These claims should be construed to maintain the proper protection for the invention first described.