EXCHANGER OF HEAT FORMING PRE-COOLER Of PLANE

The subject matter described herein relates to a heat exchanger and in particular a precooler sample flow for use with an environmental control system of aircraft.

Aircraft have power systems which are composed of several components, such as the motor, the environmental control system and a thermal management system. The systems are designed relatively independently from each other with the power that is transferred from one system to the other.

The environmental control system provides pressurized air to the cabin and the cockpit. This is typically carried out using a refrigeration unit edge. The air, referred to as bleed air, is extracted from the compressor stage of the engine. Bleed air leaves the motor at an elevated temperature (e.g. greater than 1000 °F (537.8 °C)) and is to be cooled prior to new use. Bleed air extracted from the engine is typically cooled by a motor or a precooler (HX) mounted on a rotor shaft that uses the air engine fan as a cooler. The precooler maintain the temperatures of the bleed air ducts connected to the environmental control system below the autoignition temperature of the vapors of the jet fuel/of fuel leak from the fuel tanks and central wing adjacent. Bleed air is then compressed in the compressor section of a refrigeration unit edge. The additional cooling of the bleed air may be carried out in a secondary heat exchanger, again using ram air. Bleed air is then typically expanded to the desired pressure on the turbine section. The energy generated during the expansion process may be used to drive the compressor stage and also further to drop the temperature of the bleed air. Bleed air cooled is mixed with recirculation air from the cabin, for maintaining the temperature of air to a desired level.

It should be noted that while the environmental control system is required to operate the aircraft, the weight of the system may have less impact on the performance of the fuel or the conveying capacity of the vehicle. Therefore, while the existing environmental control systems are suitable for their purposes provided, there is a need for improvement, especially in order to provide a heat exchanger lighter.

According to one aspect of the invention, there is provided a heat exchanger. The heat exchanger includes a first member having an inlet at a first end and a first flange at the opposite end. The first member is generally hollow to define a first flow path between the inlet and the first flange, the first member being made of a material of nickel-chromium. A second member is provided with a second flange at one end. The second flange is coupled to the first flange, the second member further having an outlet on an opposite second end of the second flange, the second member is generally hollow to define a second flow path between the second flange and the output, the second member is made from titanium.

Advantageously, the first member may have a first flange at the second end.

Advantageously, the second member may have a second flange at the first end.

Advantageously, the first flange may be coupled to the second flange.

Advantageously, the first member may include a first outer surface with a plurality of first fins arranged thereon.

Advantageously, the second member may include a second outer surface with a plurality of second fins arranged thereon.

Advantageously, the second member can be made from a pure titanium distributed commercially or from a titanium alloy.

Advantageously, the first member may have a length equal to or greater than 60% of the total length of the first member and the second member.

Advantageously, the second member may have a length equal to 40% of the total length of the first member and the second member.

According to another aspect of the invention, there is provided a heat exchanger system for an aircraft having an engine having a fan stage and a compressor stage. The heat exchanger system comprises a first conduit configured to receive the bleed air from the compressor stage and an environmental control system. A heat exchanger forming precooler with a first member having an inlet at a first end fluidly coupled to the first conduit, the first element is made from a nickel-chromium material. A second member is fluidly coupled in series to the first member, the second member having an output fluidly coupled to the environmental control system, the second is made from titanium.

Advantageously, the heat exchanger system may include a second conduit configured to receive air from the fan stage and flowing air on the first member and the second member in parallel.

Advantageously, the first member may include a first outer surface with a plurality of first fins arranged thereon, the second member may include a second outer surface with a plurality of second fins arranged thereon, and the second conduit may be arranged to leave air to flow over the plurality of first fins and the plurality of second fins.

In another aspect of Finvention , there is provided a method for cooling a Fair for aircraft environmental system. The method comprises the step of providing a first member having an inlet at a first end, the first member being made from nickel-chromium material. A second member is fluidly coupled in series with the first element, the second element having an output On a second end, the second member is made from titanium.

Advantageously, the first element may be configured to receive Fair at a first temperature and cooling to about 1058 °F Fair at a second temperature lower than 830 °F (443.3 °C) at a flange on an opposite end of the inlet.

Advantageously, the method may include the step of flowing Fair in parallel on the first member and the second member.

Advantageously, the method may further include the step of providing a plurality of first fins disposed on a first outer surface of the first member.

Advantageously, the method may further include the step of providing a plurality of second fins disposed on a second external surface of the second member.

Advantageously, the second element can be configured to receive air at a second temperature and for cooling Fair to a third temperature lower than about 465 °F (240 °C) to the output.

These advantages and characteristics, and the other shall become apparent more clearly from the following description taken together with the accompanying drawings.

The object, is considered to lïnvention , is particularly indicated and distinctly claimed in the claims at the end of the description. The previous features and advantages as well as other more clearly of Finvention shall become apparent from the following detailed description taken together with the accompanying drawings, in which:

ia Figure 1 is a schematic view of an environmental control system and aircraft engine according to an embodiment of the invention; and

figure 2 is a side view of a heat exchanger forming precooler for use with the environmental control system of Figure 1.

The detailed description explains embodiments of the invention, together with the advantages and characteristics, example with reference to the drawings.

To reduce the weight of aircraft components is desirable since reductions enable improved fuel economy and a increased carrying capacity of the aircraft. Embodiments of the present invention provide a heat exchanger precooler with advantages in having a reduced weight. Embodiments of the invention provide a heat exchanger precooler having a first stage made from a first material which can be driven with very high air temperatures and a second stage realised with a second lighter material.

Figure 1 illustrates a motor 22 which comprises a fan section 24, a compressor section 26 and a turbine section 28 for an aircraft. The motor 22 receives air through the fan 24 and compresses the air in the compressor 26. The air is combined with a fuel and burned in a combustion chamber 30 which increases the temperature and pressure of air. The heated air is then expanded through the turbine to generate the thrust in order to operate the aircraft.

A conduit 32 is coupled to the compressor section 26 for drawing air, sometimes referred to as bleed air, the engine 22. Because the compression of the air, the bleed air may have a temperature as high as 1100 °F (593.3 °C) in accordance with the operation of the engine 22. Bleed air flows to a heat exchanger precooler 34 forming, which reduces the temperature of the air to allow it to be used by other components. In the example embodiment, the heat exchanger forming precooler 34 reduces the temperature of the bleed air of about 1050 °F (565.5 °C) to 450 °F (232.2 °C). As will be addressed in greater detail below, the heat exchanger forming precooler 34 comprises components made of different materials which reduce the weight of the heat exchanger forming precooler 34 while allowing the operation at temperatures of high bleed air.

A second conduit 36 is coupled to the fan stage 24 for drawing air from engine coolant 22 prior to compression. The second conduit 36 made to flow air from the fan stage 24 over and around the heat exchanger forming precooler 34. The flow of air from the conduit 36 transfers heat energy from the heat exchanger forming the precooler 34 and distributed to the environment. In the example embodiment, the flow of the air in the conduit 36 is arranged in a cross flow pattern with the heat exchanger forming precooler 34. It should be noted that the duct 36 may also be arranged in a pattern to back-flow or parallel flow with the heat exchanger forming precooler 34 to provide the desired heat exchange performance.

Bleed air cooled from the heat exchanger forming precooler 34 is transferred via a passage 38 in the compensator the environmental control system 40. The environmental control system 40 can include one or more compressor turbine which continue to be cooled and to remove the energy from the energy of the bleed air. The environmental control system 40 may also include auxiliary devices including valves, water separators and air mixers for example. The conduits 32, 36, the heat exchanger forming the precooler 34 and environmental control system 40 can be collectively referred system 20, in this example. One skilled in the art can adapt the heat exchanger forming precooler 34 to be used with any environmental control system of the prior art suitable such as that described in U.S. Patent commonly held US-6,817 515 listing "Integrated system for providing the environmental monitoring of an aircraft", for example.

Maintaining In reference in Figure 2" forming a heat exchanger precooler 34 is represented having an input 42 and an outlet 44. The heat exchanger forming precooler 34 includes a first member 46 of the retract side. The first member 46 has a flange 48 opposite to the inlet 42. The first member 46 is substantially hollow, allowing the bleed air to flow along a flow path, from the inlet 42 to the flange 48. The first member 46 has a generally rectangular outer surface 50. A plurality of fins 52 are provided on the outer surface 50 to facilitate the transfer of thermal energy from the bleed air to the air located in the conduit 36. In the example embodiment, the first member 46 is made of a superalloy based on chromium-nickel austenitic, such as the Inconel® manufactured by Special Metals Corporation, having a density of about 0.30 0.32 lbs/inch³ (8301-8858 kg/m³ ).

The heat exchanger forming precooler 34 includes a second element 54 on the output side 44. The second member 54 includes a flange 56 which is coupled to the flange 48 by a plurality of bolts 58. The flanges 48, 56 may include a seal 59, such as a gasket or seal C in a crushing, for example. The second member 54 is substantially hollow, allowing the bleed air to flow along a flow path, of the flange 56 to the output 44. The second member 54 includes an outer surface 62 generally rectangular. A plurality of fins 60 are arranged On the surface 62 to further facilitate the transfer of thermal energy from the bleed air within the second member 54 to air within the conduit 36. It should be noted that the bleed air flows through the first member 46 and the second member 54 in a series arrangement while the air from the fan from the conduit 36 flows to the first member 46 and the second member 54 in a parallel arrangement.

In the example embodiment, the second member 54 is made of pure titanium distributed commercially. As used herein, the distributed commercially pure titanium has a purity equal to or greater than about 99% and has a density of 0.16 lb/inch³ (4429 kg/m³ ). The use of the distributed commercially pure titanium provides advantages in reduction of weight compared to a titanium alloy (about 45% lighter) while having a higher thermal conductivity (11-13 Btu / (hr °F ft), 19.04-22.5 W / (m K)) that llnconel (8.4 Btu / (hr °F ft), 14.54 W / (m K)).

During operation, Fair of sample is extracted from the engine 22 to a temperature of up to about 1160 °F (626.7 °C) and passes through the conduit 32 to the outlet 42 of the heat exchanger forming precooler 34. When the bleed air passes through the first member 46, thermal energy is extracted and transferred through the fins 52 Bath air in through the conduit 36. The temperature of the bleed air drop of about 1160 °F (626, 7 °C) to less than 830 °F (443.3 °C) at the flange joint. In the example embodiment, the length of the first member 46 is equal to or greater than about 60 % of the total length of the first member 46 and the second member 54 to achieve this temperature drop. In one embodiment, the length of the first member 46 is about 327 millimeters. Since the bleed air continues to flow in series through the second member 54, the additional heat energy is transferred by the fins 60 to the air located in the conduit 36. The temperature of the bleed air decreases of about 830 °F (443.3 °C) to about 465 °F (240.6 °C) to the output 44. In the example embodiment, the length of the second element 54 is about 40% of the total length of the first member 46 and the second member 54 to achieve this temperature drop. In one embodiment, the length of the second element is about 218 54 millimeters.

While the invention has been described in detail together with only a limited number of embodiments, it is understood easily that the invention is not limited to such embodiments. Instead, the present invention may be modified to include any number of variants, modifications, substitutions or equivalent non-arrangements described so far, but which correspond to the scope of the invention, which is defined by the claims. Furthermore, while different embodiments of the invention have been described, to be understood that the aspects of the invention can include only some of the disclosed embodiments. Therefore, the invention is not limited by the foregoing description " but is only limited by the scope of the attached claims.