Patent Description:
An air cycle machine (ACM) is the refrigeration unit of the environmental control system (ECS) used in pressurized aircraft. Normally an aircraft has two or more ACMs. Each ACM and its components are often referred to as an air conditioning pack, or AC pack. On most jetliners, the AC packs are located in the wing-to-body fairing (aerodynamic structure) between the two wings beneath the fuselage.

In the case of gas turbine aircraft, the air cycle cooling process is achieved primarily by expanding compressed engine air through an ACM cooling turbine with the cooled output air from the process being used directly for cabin ventilation or for cooling electronic equipment. Some or all of the AC pack exhaust air can be ducted into the pressurized fuselage and is typically mixed with filtered air from the ECS's recirculation fans, and fed into a mix manifold. On most modern jetliners, the airflow in the mix manifold is approximately half outside air and half filtered air. Air from the mix manifold is directed to overhead distribution nozzles in the various zones of the aircraft.

Temperature in each zone is typically adjusted by adding small amounts of high temperature trim air that is tapped off the AC pack air supply and regulated to be slightly higher than the cabin pressure. To transfer trim air to the zone ducting from the AC pack, a conventional aircraft utilizes a system of pressure regulating valves, pressure sensors, trim valves, check valves, mufflers, bulkhead shrouds, structural penetrations and structural reinforcement doublers. Such systems for transferring trim air to zone ducting, generically referred to herein as a trim system, also includes ducts, along with duct couplings, hangers and supports, and trim injectors. As used herein, trimming air means conditioning air, i.e., trimming up means to raise temperature of an airflow and trimming down means to lower temperature of an airflow. <CIT> relates to an air distribution system which, according to its abstract, associates a thermocouple device with a respective air distribution subsystem that delivers conditioned air to a respective zone in order to provide for individual temperature control within different zones of an aircraft. In another example, a climate control device is configured to allow individualized temperature control of the air discharged through a vent by associating a thermocouple device with the respective vent, thereby allowing for individual temperature control for a passenger onboard the aircraft. <CIT> relates to an air distribution manifold. <CIT> relates to a thermoelectric heat exchanger. <CIT> relates to an air distribution system.

Disclosed is an aircraft environmental control system as defined in appended claim <NUM>. The system comprises a mix manifold having an inlet and a plurality of outlets, a recirculation fan and an air conditioning pack fluidly coupled to the inlet, as well as a plurality of trim modules of equal configuration, located at the mix manifold and fluidly coupled to respective ones of the outlets of the mix manifold, each of the trim modules being located at the mix manifold and comprising: a first heat exchanger having an inlet and an outlet; a second heat exchanger having an inlet and an outlet; and a thermoelectric cooler (TEC) module thermally coupled between the first and second heat exchangers; a mix manifold conduit fluidly coupled to the inlet of the first heat exchanger; a zone supply conduit fluidly coupled to the outlet of the first heat exchanger; an exhaust conduit fluidly coupled to the outlet of the second heat exchanger, wherein, for each TEC module: the TEC module is configured to operate in a first mode or a second mode, depending on a temperature within the zone supply conduit and a target temperature, and wherein: in the first mode, the TEC module is configured to transfer thermal energy from the first heat exchanger to the second heat exchanger; and in the second mode the TEC module is configured to transfer thermal energy from the second heat exchanger to the first heat exchanger; a temperature sensor in the zone supply conduit, wherein the TEC module is configured to operate in the first mode or the second mode depending on the temperature sensed by the temperature sensor and the target temperature; an exhaust fan fluidly coupled to the outlet of the second heat exchanger and the exhaust conduit to draw air from an ambient environment around the mix manifold into the inlet of the second heat exchanger; wherein: the plurality of outlets of the mix manifold are fluidly coupled to the mix manifold conduit of respective ones of the plurality of trim modules; and an exhaust manifold fluidly coupled to the exhaust conduit of the second heat exchanger.

In addition to one or more of the above disclosed aspects of the trim module, or as an alternate, the TEC module includes a plurality of thermoelectric coolers configured as a circuit.

Further disclosed is an aircraft including: a cabin including a zone, the zone including a zone duct; a bay located below the cabin; and an environmental control system as disclosed above disposed in the bay, wherein: the zone supply conduit of the first heat exchanger is fluidly coupled to the zone duct of the zone.

In addition to one or more of the above disclosed aspects of the aircraft, or as an alternate, the TEC module includes a plurality of thermoelectric coolers configured as a circuit.

In addition to one or more of the above disclosed aspects of the aircraft, or as an alternate, the plurality of thermoelectric coolers are electrically coupled in series or parallel.

In addition to one or more of the above disclosed aspects of the aircraft, or as an alternate, the plurality of thermoelectric coolers are thermally coupled in series or parallel.

Turning to <FIG>, an aircraft <NUM> has a cabin <NUM> that is divided into different zones <NUM>, e.g., first and second zones 120A, 120B. A bay <NUM> of the aircraft <NUM> has an ECS (or system) <NUM>. The bay <NUM> is typically located below the cabin <NUM>.

The system <NUM> includes a centralized mix manifold <NUM> that has at least one inlet <NUM> to receive cabin air from the cabin <NUM>. As shown by way of example, the manifold includes first and second inlets 160A, 160B but these could be a single inlet. The at least one inlet <NUM> is fluidly coupled to at least one inlet duct <NUM>. In the example shown in <FIG>, in which the mix manifold <NUM> has first and second inlets 160A, 160B, first and second inlet ducts 165A, 165B are fluidly coupled to the first and second inlets 160A, 160B.

At least one recirculation fan <NUM> draws air from the cabin <NUM> to the mix manifold <NUM> via the at least one inlet duct <NUM>. In the example shown in <FIG>, in which the mix manifold <NUM> has first and second inlet ducts 165A, 165B,first and second recirculation fans 170A, 170B are provided which draw air from the cabin <NUM> into the inlets.

Cabin return air typically flows from vents located near the intersection of the fuselage and the cabin floor. The return flow moves into a cheek area of the cargo bay from which the recirculation fans 170A, 170B and thermoelectric coolers (TECs), discussed below, draw in the return flow. The cabin air is mixed with conditioned bleed air that is processed through first and second AC packs 180A, 180B. The ECS packs 180A, 180B are typically located in outside of the aircraft pressure vessel in an unpressurized bay. As shown in <FIG>, the first and second AC packs 180A, 180B are fluidly coupled with the first and second inlet ducts 165A, 165B, between the first and second recirculation fans 170A, 170B and the mix manifold <NUM>. The mix manifold <NUM> has outlets <NUM>, e.g., first and second outlets 190A, 190B. The outlets <NUM> of the mix manifold <NUM> are fluidly coupled with the first and second zones 120A, 120B via zone ducts <NUM>, e.g., first and second zone ducts 200A, 200B.

To accommodate different preferences in the zones 120A, 120B, air exiting the mix manifold <NUM> may need further conditioning by being heated or cooled by, e.g., <NUM> degrees Celsius, as a non-limiting example. According to the embodiments, to provide such further conditioning, trim modules, e.g., first and second trim modules <NUM>, <NUM>, are provided such that each of the zone ducts 200A, 200B is fluidly coupled to one of the trim modules <NUM>, <NUM>. Each of the trim modules <NUM>, <NUM> may have a same configuration as each other so that further reference will be to the trim module <NUM>.

Turning to <FIG>, details of the trim module <NUM> are shown. The trim module <NUM> includes at least two heat exchangers <NUM>, e.g., a first heat exchanger (a zone air heat exchanger) 220A and a second heat exchanger (a cabin return air heat exchanger) 220B. A thermoelectric cooler (TEC) module <NUM> is interposed and thermally coupled between the first and second heat exchangers 220A, 220B. The TEC modules can be Peltier devices that utilize the Peltier effect to create a heat flux at the junction of two different types of materials. A Peltier device (cooler, heater, or thermoelectric heat pump) is a solid-state active device which transfers heat from one side of the device to the other based on application of a voltage across the device. The direction of heat flow is based on the polarity of the voltage as will be understood by the skilled.

The TEC module <NUM> is operationally coupled to the system <NUM>, e.g., via leads 230A that receive power (e.g., supply voltage) and control signals from a system control 140A. As can be appreciated, voltage magnitude and polarity to the TEC module <NUM> will control its direction and magnitude of heat transfer, e.g., from the first heat exchanger 220A to the second heat exchanger 220B and vice versa. The TEC module <NUM> may include a plurality of TECs, <NUM>, <NUM> configured as a circuit <NUM>. The plurality of TECs <NUM>, <NUM> may be electrically coupled in series or parallel, thermally coupled in series or parallel, or for either coupling, as a combination of series and parallel, and may be organized as a stack, to achieve a desired thermal effect, improve fault tolerances and increase heat transfer capacity. To increase heat transfer via the TEC module <NUM>, the heat exchangers 220A, 220B, may be manufactured from aluminum.

The trim module <NUM> may include various conduits <NUM>. For example, a mix manifold conduit 240A is fluidly coupled between an inlet 220A1 of the first heat exchanger 220A and, e.g., the first outlet 190A (<FIG>) of the mix manifold <NUM>. A zone supply conduit 240B is fluidly coupled between an outlet 220A2 of the first heat exchanger 220A and, e.g., the first zone duct 200A (<FIG>) that is fluidly coupled to the first zone 120A. The heat exchanger 220B is intended to draw cabin return air from the ambient environment surrounding the mix manifold <NUM> into an inlet 220B1 using the exhaust fan <NUM> (discussed below). An exhaust conduit 240E is fluidly coupled between an outlet 220B2 of the second heat exchanger 220B and a low-pressure TEC exhaust (overboard) manifold <NUM> (or exhaust manifold, for simplicity) of the system <NUM>.

The trim module <NUM> may include a temperature sensor <NUM> located in the zone supply conduit 240B. An exhaust fan <NUM> may be fluidly coupled between the outlet 220B2 of the second heat exchanger 220B and the exhaust conduit 240E. The exhaust fan <NUM> may create negative pressure that draws air from bay <NUM> into the inlet 220B1 of the second heat exchanger 220B. This enables mixing of air from bay <NUM> and the cabin <NUM> within the second heat exchanger 220B when conditioning air from the mix manifold <NUM>. The exhaust fan <NUM> is operationally coupled to the system <NUM>, e.g., via leads 230B, to receive power (e.g., supply voltage) and control signals. As can be appreciated, the supply voltage and control signals to the exhaust fan <NUM> may differ from the supply voltage and control signals to the TEC module <NUM>. That is, while the TEC module <NUM> may be controlled to alternatively direct heat transfer between the first and second heat exchangers 220A, 220B, the exhaust fan <NUM> is configured to exhaust waste air in one direction, i.e., away from the second heat exchanger 220B. The magnitude of the supply voltage to the exhaust fan <NUM> may be controlled to change the flow rate of air across the second heat exchanger 220B, depending on cooling or heating requirements. With the exhaust fan <NUM>, waste air can be directed overboard from the exhaust manifold <NUM>, or used for another purpose such as a driving a power turbine of an air cycle machine (ACM). Directing the exhaust air to the exhaust manifold <NUM> from the trim module <NUM> avoids adding unwanted heating and cooling of the aircraft cabin <NUM>.

The TEC module <NUM> is configured to operate in a first mode or a second mode, depending on a temperature within the zone supply conduit 240B and a target temperature. In the first mode, the TEC module <NUM> is configured to transfer thermal energy from the first heat exchanger 220A to the second heat exchanger 220B. In the second mode, the TEC module <NUM> is configured to transfer thermal energy from the second heat exchanger 220B to the first heat exchanger 220A. Thus, during operation, a voltage magnitude and polarity to the TEC module <NUM> may be utilized to regulate the outlet temperatures of heat exchangers 220A, 220B to raise or lower the temperature of the mix manifold <NUM> by approximately <NUM> degrees Celsius, as indicated. That is, the trim module <NUM> provides for a heating and cooling capability of a zone <NUM> by varying the magnitude and polarity of voltage applied to the TEC module <NUM>. When operating in either mode, as indicated above, the magnitude of the voltage to the exhaust fan <NUM> may be controlled to change the flow rate of air across the second heat exchanger 220B, depending on cooling or heating requirements.

With the above embodiments, a heating and cooling capability of the TEC module <NUM> enables optionally running the ECS <NUM> at a higher outlet temperature, which may translate into extra system capacity. Alternatively, a smaller ECS may be utilized. Locating the trim module <NUM> at the mix manifold <NUM> enables a low integration cost and weight for the trim module <NUM> because the system wiring and the exhaust manifold <NUM> are confined to the bay <NUM>. As each trim module <NUM> is configured the same, there is a reduction in recurring manufacturing costs.

In addition to the above identified benefits, the configuration enables an elimination of, e.g., diverter valves, which enables the ability to provide steady exhaust flow for other uses. Conventional pneumatic zone trim valves, trim injectors, mufflers, ducting, couplings and its associated mounting hardware is also eliminated.

Claim 1:
An environmental control system for an aircraft, comprising:
a mix manifold (<NUM>) having an inlet and a plurality of outlets;
a recirculation fan and an air conditioning pack fluidly coupled to the inlet;
a plurality of trim modules (<NUM>), having a same configuration as each other, fluidly coupled to respective ones of the plurality of outlets of the mix manifold, each of the trim modules (<NUM>) is located at the mix manifold (<NUM>), each trim module comprising:
a first heat exchanger (220A) having an inlet and an outlet;
a second heat exchanger (220B) having an inlet and an outlet; and
a thermoelectric cooler, TEC, module (<NUM>) thermally coupled between the first and second heat exchangers (220A, 220B);
a mix manifold conduit (240A) fluidly coupled to the inlet of the first heat exchanger;
a zone supply conduit (240B) fluidly coupled to the outlet of the first heat exchanger;
an exhaust conduit (240E) fluidly coupled to the outlet of the second heat exchanger,
wherein, for each TEC module:
the TEC module (<NUM>) is configured to operate in a first mode or a second mode, depending on a temperature within the zone supply conduit (240B) and a target temperature, and
wherein:
in the first mode, the TEC module (<NUM>) is configured to transfer thermal energy from the first heat exchanger (220A) to the second heat exchanger (220B); and
in the second mode the TEC module (<NUM>) is configured to transfer thermal energy from the second heat exchanger (220B) to the first heat exchanger (220A);
a temperature sensor (<NUM>) in the zone supply conduit (240B), wherein the TEC module (<NUM>) is configured to operate in the first mode or the second mode depending on the temperature sensed by the temperature sensor (<NUM>) and the target temperature;
an exhaust fan (<NUM>) fluidly coupled to the outlet of the second heat exchanger (220B) and the exhaust conduit (240E) to draw air from an ambient environment around the mix manifold (<NUM>) into the inlet (220B1) of the second heat exchanger;
wherein:
the plurality of outlets of the mix manifold (<NUM>) are fluidly coupled to the mix manifold conduit (240A) of respective ones of the plurality of trim modules (<NUM>); and
an exhaust manifold (<NUM>) fluidly coupled to the exhaust conduit (240E) of the second heat exchanger.