Power plants – Combustion products used as motive fluid – With lubricators
Patent
1993-06-18
1995-08-08
Fox, John C.
Power plants
Combustion products used as motive fluid
With lubricators
165 41, F02C 714
Patent
active
054388236
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to heat exchange apparatus, in particular heat exchange apparatus for use in connection with gas turbine engines, especially aeroengines.
BACKGROUND OF THE INVENTION
In gas turbine aeroengines it is necessary to maintain the engine fuel and the engine lubricating oil within predetermined ranges of temperature so that the fuel and oil temperatures are suitable throughout the whole range of engine operation.
It is common practice to use the engine fuel as a heat sink to cool the engine lubricating oil, using a fuel cooled oil cooler heat exchanger. However, in the operation of certain large passenger aircraft it has been found to be necessary for the engine lubricating oil to be independently heated or cooled to avoid the fuel temperature straying outside acceptable limits.
SUMMARY OF THE INVENTION
The present invention seeks to provide a more convenient arrangement whereby the engine lubricating oil can be selectively heated or cooled prior to being in heat exchange relationship with the engine fuel.
Accordingly, the present invention provides a heat exchange apparatus comprising a first heat exchanger arranged to receive engine lubricating oil from an engine and put the oil in heat exchange relationship with a heat exchange medium and a second heat exchanger arranged to receive the engine oil from the first heat exchange apparatus, put it in heat exchange relationship with fuel for the engine and pass the oil back to the engine, and means for controlling the temperature of the heat exchange medium before it enters the first heat exchanger so as to selectively cool and heat the lubricating oil from the engine.
Also according to the invention, a heat exchange apparatus for a combustion engine having a lubrication oil system and a fuel supply system, comprises a first heat exchange means arranged to receive oil from the lubrication oil system and to put the oil in heat exchange relationship with a heat exchange medium, a second heat exchange means arranged to receive the oil from the first heat exchange means, put the oil in heat exchange relationship with fuel in the fuel system and to return the engine oil to the engine, high and low temperature sources of said heat exchange medium, and valve means for controlling flow from the high and low temperature sources of the heat exchange medium through the first heat exchange means such that the direction of heat flow between the oil and the heat exchange medium can be changed as necessary to prevent the fuel temperature from straying beyond predetermined limits.
If the engine is a turbofan aeroengine, the heat exchange medium can either be a flow of hot air from the engine's compressor or a flow of cooler air from the freestream or from a bypass duct of the gas turbine engine.
A control valve or valves can be provided in order to control the flow of air into the first heat exchanger.
The present invention will now be more particularly described with reference to the accompanying drawing which shows diagramatically one form of heat exchange apparatus according to the present invention.
BRIEF DESCRIPTION OF THE INVENTION
The sole drawing diagrammatically shows park of a turbofan aeroengine in longitudinal axial cross-section, together with a heat exchange apparatus in accordance with the invention and the fluid flows associated with it.
DETAILED DESCRIPTION OF THE INVENTION
Referring to the drawing, which is not to scale, the heat exchange apparatus or system 10 comprises a first air/oil heat exchanger 12 which is located in a duct 14 formed between the outer and inner walls 16A,16B of an outer casing or cowling 16 of the engine. Cool low pressure air 17 is allowed to enter the duct 14 from a smaller duct 19 under the control of a fully variable butterfly or flap valve 20 which has an actuator (not shown) operated under software control by an electronic engine controller (EEC, not shown). Both the actuator and the electronic controller may be of types generally well known in the industry. The duct 14
REFERENCES:
patent: 4696156 (1987-09-01), Burr et al.
patent: 5121598 (1992-06-01), Butler
Clarke Andrew
Loxley Russell A.
Fox John C.
Rolls-Royce PLC
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