AIR CYCLE CONDENSER COLD INLET HEATING USING INTERNALLY FINNED HOT BARS
An environmental control system (ECS) includes an air cycle machine with an expansion turbine and a condenser having a cold air inlet connected to receive air from the expansion turbine. The condenser has hollow, internally finned hot bars positioned at the cold air inlet to prevent ice formation at the cold air inlet.
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The present invention generally relates to fluid conditioning apparatus, systems and methods, and is more particularly concerned with such systems employed to meet the physiological air requirements of passenger aircraft.
Systems employed to meet the physiological air requirements of passenger aircraft may be referred to as environmental control systems (ECS). A typical aircraft ECS may employ a three-wheel air cycle machine in which humid high pressure air is cooled in a reheater and condenser assembly. Water condenses from the high pressure air and is mostly removed in a water extractor device. This drier air is then expanded in a cooling turbine and is used to cool the condenser. After passing through the condenser the air is delivered to the aircraft cabin.
The cold air leaving the cooling turbine may still have some residual humidity which may form ice because typical turbine discharge temperatures may be well below 0° F. This ice can build up on a cold inlet face of the condenser, blocking cooling flow to the condenser and reducing the amount of humidity which can be removed. Removal of such ice buildup may be achieved with an ice melting system but such a system may consume substantial amounts of energy.
As can be seen, there is a need for an ECS in which such ice buildup does not occur. Moreover there is a need for such an ECS in which only a small amount of energy is consumed in order to preclude such ice buildup.
SUMMARY OF THE INVENTIONIn one aspect of the present invention, an environmental control system (ECS) may comprise: an air cycle machine with an expansion turbine; and a condenser having a cold air inlet connected to receive air from the expansion turbine, the condenser having hollow, internally finned hot bars positioned at the cold air inlet.
In another aspect of the present invention, a condenser for an aircraft ECS may comprise: a plate-fin core having a cold-inlet side; and hollow internally finned hot bars disposed transversely across the cold-inlet side of the core.
In still another aspect of the present invention, a method for conditioning air for delivery to an aircraft cabin may comprise the steps of: passing the air through an expansion turbine to cool the air; heating the air by passing the air over hollow internally finned hot bars attached to a cold-inlet side of a condenser; passing the air into a cold-inlet side of a condenser; and passing the air into the cabin.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.
The following detailed description is of the best currently contemplated modes of carrying out exemplary embodiments of the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.
Various inventive features are described below that can each be used independently of one another or in combination with other features.
Broadly, embodiments of the present invention generally provide an ECS with hollow header tubes positioned at a cold air inlet of a heat exchanger. Heated gas may pass through the header tubes so that ice buildup at the inlet is precluded. The header tubes may be uniquely shaped so that their external temperature is maintained above a freezing point of water with introduction of only a minimal amount of energy.
Referring now to
Dehumidified air may then emerge from the water trap 24, pass through the reheater and then enter an expansion turbine 12-2 of the air-cycle machine. The dehumidified air may be cooled by the expansion turbine 12-2. Cooled air from the expansion turbine 12-2 may enter the condenser 22 at a cold-air inlet 22-1 of the condenser 22. As the cooled air passes through the condenser 22, it may be warmed by air flow entering a hot air inlet 22-2 of the condenser 22. Air emerging from a cooled-air outlet 22-3 of the condenser 22 may be directed though the ECS outlet 26 into a cabin (not shown) of an aircraft.
It may be noted that, even though the condenser 22 and water trap 24 may remove most of the humidity from the air passing through the ECS 10, some residual humidity may remain in the air after it emerges from the expansion turbine 12-2. Because, air emerging from the expansion turbine 12-2 may be at a temperature below the freezing point of water, there is a risk that this residual humidity could coalesce into ice formation at the cold-air inlet 22-1 of the condenser 22. In order to assure that ice formation does not occur, the condenser 22 may be provided with hollow hot bars 32 (shown in
Referring now to
In operation, cold air 34 emerging from the expansion turbine 12-2 of
Referring now to
In an exemplary embodiment, the hot bar 32 may have a front-to-back width of about 0.6 inch and a height of about 0.25 inch. The hot bar 32 may be constructed as an aluminum extrusion. The passageway 56 may have a front-to-back width of about 0.25 inch and a height of about 0.15 inch. The fins 58 may project into the passageway 56. The fins 58 may have a length of about 0.045 inch and a thickness of about 0.030 inch. The fins 58 may projects from the lateral surface elements 52 and may be arranged so that they do not touch one another. Within such a configuration, bleed air may migrate across the passageway 56 as it flows along the length of the hot bar 32. This feature may be advantageous in that it may allow for full flow through the entire cross-sectional areas of the passageway 56 even if an inlet portion of the passageway 56 becomes inadvertently blocked with weld spatter during welding assembly of the core 30.
Presence of the fins 58 in the passageway 56 may provide the advantageous benefit of decreasing the hydraulic radius of the passageway 56 and a corresponding increase in convection coefficient of the passageway 56. Consequently, the fins 58 may provide the beneficial effect of allowing outer surfaces of the hot bars 32 to be maintained at ice-prevention temperature while passing only a minimal quantity of bleed air through the hot bars 32.
Referring now to
Referring now to
Referring now to
It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.
Claims
1. An environmental control system (ECS) comprising:
- an air cycle machine with an expansion turbine; and
- a condenser having a cold air inlet connected to receive air from the expansion turbine,
- the condenser having hollow, internally finned hot bars positioned at the cold air inlet.
2. The ECS of claim 1 wherein the condenser is a plate-fin condenser.
3. The ECS of claim 1 wherein the hot bars are positioned transversely across the cold air inlet.
4. The ECS of claim 1 wherein the hot bars are connected to a bleed-air plenum.
5. The ECS of claim 4 further comprising a bleed air inlet connected to the plenum.
6. The ECS of claim 5 further comprising a flow regulator connected to the bleed air inlet.
7. A condenser for an aircraft ECS comprising:
- a plate-fin core having a cold-inlet side; and
- hollow internally finned hot bars disposed transversely across the cold-inlet side of the core.
8. The condenser of claim 7 further comprising:
- layers of cold fins,
- the hot bars having rounded leading surface elements,
- the hot bars being attached to the cold fins at the cold-inlet side so that the rounded leading surface elements project outwardly from the cold fins.
9. The condenser of claim 7 wherein the hot bars are aluminum extrusions.
10. The condenser of claim 7 further comprising a bleed-air plenum connected to the hot bars.
11. The condenser of claim 10 wherein the bleed-air plenum is bounded by a divider bar attached to the condenser and a frame member of the condenser.
12. The condenser of claim 7 wherein the hot bar comprises:
- outer-surface elements surrounding a passageway;
- fins attached to one or more of the outer-surface elements and projecting into the passageway.
13. The condenser of claim 12 wherein the fins are attached to opposed lateral surface elements and the fins extend along an entire length of the hot bar.
14. The condenser of claim 12 wherein the passageway has front-to-back width of about 0.25 inch and a height of about 0.15 inch.
15. The condenser of claim 12 wherein the fin has a length of about 0.045 inch and a thickness of about 0.030 inch.
16. The condenser of claim 12 wherein:
- a first set of two of the fins projects from a first one of the lateral surface elements;
- a second set of two of the fins projects from a second one of the lateral surface elements: and
- the fins of the first set do not touch the fins of the second set.
17. A method for conditioning air for delivery to an aircraft cabin comprising the steps of:
- passing the air through an expansion turbine to cool the air;
- heating the air by passing the air over hollow internally finned hot bars attached to a cold-inlet side of a condenser;
- passing the air into a cold-inlet side of a condenser; and
- passing the air into the cabin.
18. The method of claim 17 further comprising passing heated gas into and through the hot bars to heat the hot bars.
19. The method of claim 17 further comprising the step of maintaining temperature of a leading outer surface element of the hot bars at a temperature above a freezing point of water.
20. The method of claim 19 wherein the step of maintaining temperature of the leading outer surface comprises transferring heat from bleed of an engine of the aircraft into internal fins within a hollow passageway of the hot bar.
Type: Application
Filed: Sep 13, 2011
Publication Date: Mar 14, 2013
Applicant: HONEYWELL INTERNATIONAL INC. (MORRISTOWN, NJ)
Inventors: Joe Borghese (Yucca Valley, CA), Tim Moorhouse , Jorge Alvarez (Buena Park, CA)
Application Number: 13/231,351
International Classification: F25B 9/00 (20060101); F28F 3/02 (20060101);