HEAT EXCHANGER ASSEMBLY FOR AIRCRAFT ECS
An aircraft environmental conditioning system is disclosed that includes an air cycle system for conditioning a flow of hot compressed air by reducing its temperature and pressure. The air cycle system includes a heat exchanger having a heat rejection side in fluid communication with the airflow and a heat absorption side in fluid communication with external unconditioned air. The system also includes an airflow path from an external air inlet to the heat absorption side of the heat exchanger. A centrifugal separator is disposed in the airflow path, and includes a tubular body portion having an inlet that receives airflow, a deflector in the tubular body portion that imparts a vortex motion to airflow in the tubular body portion, and an outlet portion that includes a clean air outlet in fluid communication with the heat absorption side of the heat exchanger and a scavenge air outlet for removing particulate matter.
This invention relates to environmental air conditioning systems (ECS), and more specifically to air cycle environmental air conditioning systems such as used on aircraft.
Aircraft that fly at altitudes above that at which ambient air is suitable for crew, passengers, cargo, or equipment are often equipped with air cycle environmental air conditioning systems to provide pressurized conditioned air. These air conditioning systems typically utilize a pressurized air bleed from a turbine fan engine or an auxiliary power unit (APU), or in some cases from an electrically-powered compressor as a source of compressed air that flows along an airflow path through the air cycle environmental air conditioning system to produce conditioned air for the cockpit and passenger cabin or other pressurized areas of the aircraft. The compressed air that is fed into these systems is typically at a temperature and pressure far in excess of the normal temperature and pressure for conditioned air to be supplied to the cockpit and passenger cabin, so it must be expanded and cooled by the air conditioning system before it can be discharged as conditioned air. Aviation air cycle environmental conditioning systems typically process the bleed air through multiple cycles of cooling/pressure reduction and compression/heating. Cooling and pressure reduction is accomplished with heat exchangers (including condensers) and with turbines (which also extract work from the bleed air), while compression/heating is accomplished with compressors and reheaters. Many systems include at least one heat exchanger that utilizes external air to cool the bleed air.
Air cycle-based aviation ECS systems are required to operate under a variety of conditions. Some of these conditions can involve exposure to airborne particulates, which can result in the accumulation of particulate debris on and around the heat absorption side of heat exchangers that use external air to absorb heat from the bleed air. Continued accumulation of such debris can ultimately lead to partial to complete or near-complete airflow blockage on the heat absorption side of the heat exchanger, which can result in reduced cooling performance, fan surge, broken fan blades, and system failure. Fan blade breakage can also involve failed journal bearings, turbine rotor rubs, and smoke events in the cabin.
BRIEF DESCRIPTION OF THE INVENTIONAccording to an aspect of the invention, an aircraft environmental conditioning system comprises an air cycle conditioning system for conditioning an airflow comprising hot compressed air by reducing its temperature and pressure. The air cycle conditioning system includes a heat exchanger having a heat rejection side in fluid communication with the airflow and a heat absorption side in fluid communication with external unconditioned air. The system also includes a heat exchanger assembly comprising an external air inlet and a first flow path from the external air inlet to the heat absorption side of the heat exchanger and from the heat absorption side of the heat exchanger to an external air exhaust outlet. A particulate separator is disposed in the first flow path between the external air inlet and the heat exchanger, and is movable between a deployed position in the first flow path and a stand-by position not in the first flow path.
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:
Turning now to
The centrifugal separator(s) are movable between a deployed position in the external inlet air flow path (i.e., first flow path) and a stand-by position not in the external inlet air flow path.
In some embodiments, the heat exchanger assembly further comprises a second flow path, without a centrifugal separator disposed therein, connecting the external air inlet to the heat absorption side of the heat exchanger. An example of such a configuration is depicted in
The invention allows, but does not require, that centrifugal separators can be controllably interposed in an external inlet air stream for an aircraft ECS heat exchanger. The exercise of such control can provide beneficial technical effects such as eliminating or minimizing pressure drop by excluding the centrifugal separators from the air flow path under conditions where lower airborne particulate levels are expected, and also utilizing the centrifugal separators to remove or reduce airborne particulates under conditions where greater airborne particulate levels are expected. Accordingly, in some embodiments such as shown in
In some embodiments, the controller 27 (
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. 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.
Claims
1. An aircraft environmental conditioning system, comprising
- an air cycle conditioning system for conditioning an airflow comprising hot compressed air by reducing its temperature and pressure, the air cycle conditioning system including a heat exchanger having a heat rejection side in fluid communication with said airflow and a heat absorption side in fluid communication with external unconditioned air;
- a heat exchanger assembly comprising an external air inlet and a first flow path from the external air inlet to the heat absorption side of the heat exchanger and from the heat absorption side of the heat exchanger to an external air exhaust outlet;
- a particulate separator disposed along the first flow path between the external air inlet and the heat exchanger, the particulate separator being movable between a deployed position in the first flow path and a stand-by position not in the first flow path.
2. The aircraft environmental conditioning system of claim 1, wherein the heat exchanger assembly further comprises a fan disposed in the first flow path.
3. The aircraft environmental conditioning system of claim 1, wherein the particulate separator is a screen or mesh.
4. The aircraft environmental conditioning system of claim 1, wherein the particulate separator is a centrifugal separator comprising a tubular body portion having an inlet that receives external air from the external air inlet, a deflector in the tubular body portion that imparts a vortex motion to air flow in the tubular body portion, and an outlet portion that comprises a clean air outlet in fluid communication with the heat absorption side of the heat exchanger and a scavenge air outlet for removing particulate matter.
5. The aircraft environmental conditioning system of claim 4, comprising a plurality of said centrifugal separators disposed along the first flow path.
6. The aircraft environmental conditioning system of claim 1, wherein the particulate separator is configured to, or is disposed in a housing configured to align and seal with a conduit along the first flow path, thereby directing the external air flow along the first path into the tubular body inlet.
7. The aircraft environmental conditioning system of claim 1, further comprising a controller configured to direct the particulate separator to move between the deployed position and the stand-by position.
8. The aircraft environmental conditioning system of claim 7, wherein the external air inlet comprises a ram external air inlet and a secondary external air inlet, and the controller is configured to direct air from the ram air inlet along the first flow path when the centrifugal separator is in the stand-by position, and is configured to deploy the particulate separator when the secondary external air inlet is open.
9. The aircraft environmental conditioning system of claim 7, wherein the controller is configured to deploy the particulate separator if the aircraft is on or within proximity to the ground or if the fan is operating.
10. The aircraft environmental conditioning system of claim 1, wherein the heat exchanger assembly further comprises a second flow path, without a particulate separator disposed therein, connecting the external air inlet to the heat absorption side of the heat exchanger.
11. The aircraft environmental conditioning system of claim 10, wherein the external air inlet comprises a ram external air inlet and a secondary external air inlet, the first flow path is along a path from the secondary external air inlet to the particulate separator to the heat absorption side of the heat exchanger, and the second flow path is along a path from the ram external air inlet to the heat absorption side of the heat exchanger.
12. The aircraft environmental conditioning system of claim 10, further comprising a controller configured to direct air from the external air inlet between the first flow path and the second flow path.
13. The aircraft environmental conditioning system of claim 12, wherein the controller is configured to direct air from the external air inlet to the first flow path when the aircraft is on or proximate to the ground or the fan is operating, and is configured to direct air from the external air inlet to the second flow path when the aircraft is in flying at altitude or the fan is not operating.
14. The aircraft environmental conditioning system of any of claims 1-13, wherein the particulate separation device is configured to separate particles of 4 μm to 3 mm from air in the first flow path.
Type: Application
Filed: Nov 24, 2014
Publication Date: May 26, 2016
Inventors: Harold W. Hipsky (Willington, CT), Thomas M. Zywiak (Suffield, CT)
Application Number: 14/552,121