Balancing the heat flow between components associated with a gas turbine engine

• US 4,773,212 A
• Filed: 04/01/1981
• Issued: 09/27/1988
• Est. Priority Date: 04/01/1981
• Status: Expired due to Term

• Current Assignee: United Technologies Corporation (Rtx Corporation)
• Original Assignee: United Technologies Corporation (Rtx Corporation)
• Inventors: Beck, John P., Griffin, James G., McHale, Robert J., Dreisbach, Raymond A. Jr.
• Primary Examiner(s): Casaregola, Louis J.
• Application Number:
  US06/249,765
• Time in Patent Office: 2,736 Days
• Field of Search: 60/39.83, 60/266, 60/267, 60/226 R, 60/39.08, 60/39.27, 60/39.02, 165/41, 165/51
• US Class Current: 60/772
• CPC Class Codes: F02C 7/224 Heating fuel before feeding to the burner

Abstract

Heat transfer systems for maintaining a thermal balance between a gas turbine engine and heat generating accessory components of the engine are disclosed. In the embodiment illustrated, heat is removed from the cooling system 48 of an electrical generator 46 and is transferred to the fuel supply system 32 of the engine. In one detailed embodiment, the cooling system 48 is in direct heat transfer communication with the downstream portion 62 of the fuel supply system through a heat exchanger 76 and in indirect heat transfer communication with the upstream portion 60 of the fuel supply system through the fuel recirculation system 42.

Claims

1. A method for maintaining a thermal balance in a gas turbine engine operating at variable operating conditions which has a combustion section for burning a first portion of fuel to produce power and which has, a fuel system to supply fuel, the fuel system having a fuel at a temperature which is lower than the freezing point of water under certain operating conditions, wherein a fuel control having an inlet and an outlet for fuel is used to control the flow of fuel in the fuel system and wherein a generator for producing electrical power is driven by the engine, including the steps of:

transferring heat from the electrical generator to the feel control by transferring heat from the electrical generator to a second portion of fuel in the fuel system to heat the fuel and to cool the electrical generator,

flowing all of the heated fuel to the inlet of the fuel control and through the fuel control to the outlet of the fuel control to heat the fuel control to inhibit the formation of ice in the fuel control, and

flowing an amount of fuel through the fuel control which is greater than the first portion of fuel and which is greater than the second portion of fuel.

2. The method for maintaining a thermal balance as claimed in claim 1 wherein the step of transferring heat from the electrical generator to the fuel control includes the step of recirculating a portion of the fuel flowed through the fuel control from a point in the fuel supply system downstream of the fuel control to a point in the fuel supply system upstream of the fuel control and transferring heat from the electrical generator to the fuel being recirculated.

3. The method for maintaining a thermal balance as claimed in claim 2 wherein the step of transferring heat from the electrical generator to the fuel control includes the step of circulating a cooling fluid through the electrical generator and transferring heat from the cooling fluid to the recirculated fuel.

4. A method for maintaining a thermal balance in an axial flow gas turbine engine operating at low power and having a combustion section in which fuel is burned to produce power, wherein a fuel supply system is used to deliver fuel to the combustion chamber, wherein a fuel control having an inlet and outlet in the fuel supply system is used to control the flow of fuel through the supply system, wherein a heat exchanger in the fuel supply system downstream of the fuel control is used to cool oil circulated through the engine by rejecting heat from the oil to the fuel and wherein an electrical generator driven by the engine is used to produce electrical power and waste heat, including the steps of:

transferring heat from the electrical generator to a cooling fluid;

transferring heat between the cooling fluid and the fuel supply system at a point downstream of the engine oil heat exchanger;

recirculating a portion of the fuel flowing through the fuel control from a point between the engine oil heat exchanger and the fuel control to a point upstream of the fuel control;

transferring heat from the cooling fluid to the recirculated fuel;

wherein the effect on the cooling fluid temperature of transient heat transfer from the fuel downstream of the fuel control to the cooling fluid during sudden reductions in power is reduced by transferring heat from the cooling fluid to fuel upstream of the fuel control.

5. A turbofan, gas turbine engine having a fan bypass duct into which pressurized air fron the fan is discharged and of the type in which fuel consumption is controlled by a fuel control having an inlet and outlet for fuel, in which bearings are used and engine oil is used to lubricate the engine bearings and in which an electrical generator producing electrical power produces excess heat and is cooled by a cooling fluid wherein the improvement comprises:

(1.) a fuel supply system which includes

(1a) an upstream portion in fluid communication with the inlet of the fuel control, and

(1b) a downstream portion in fluid communication with the outlet of the fuel control, the downstream portion including

(1bi) a first heat exchanger in fluid communication with the downstream portion of the fuel line for transferring heat from the engine oil to the fuel,

(1bii) a second heat exchanger in fluid communication with the downstream portion of the fuel line for transferring heat between the cooling fluid and the fuel;

(2) a fuel recirculation system which includes

(2a) a conduit for recirculating pressurized fuel which extends between the downstream portion of the fuel supply system and the upstream portion of the fuel supply system,

(2b) a hydraulic vane controller in fluid communciation with the fuel recirculation conduit,

(2c) a third heat exchanger in fluid communication with the fuel recirculation conduit for transferring heat from the cooling fluid to the recirculated fuel; and

(3) a cooling system for the electrical generator which includes

(3a) a fourth heat exchanger for transferring heat from the cooling fluid to fan air,

(3b) a conduit for ducting fan air from the bypass duct to the fourth heat exchanger, and

(3c) a conduit for cooling fluid in fluid and heat transfer communication with the electrical generator, the fourth heat exchanger, the third heat exchanger and the second heat exchanger;

wherein the third heat exchanger transfers heat from the cooling fluid to fuel in the upstream portion of the fuel supply system to minimize the transient effect of the heat transferred from the engine oil to the cooling fluid through the first and second heat exchangers in the downstream portion of the fuel line during a sudden reduction in the power setting of the engine.

6. In a gas turbine engine of the type in which fuel having water molecules is burned to produce power and the flow of fuel is controlled by a fuel control having an inlet and an outlet, and in which heat is produced by an electrical generator driven by the engine, the improvement which comprises:

means for transferring heat from the electrical generator to the fuel control which includes

a heat exchanger in heat transfer communciation with the electrical generator,

a fuel pump for pressurizing fuel passing through the fuel control, and

a conduit for recirculating pressurized fuel which is in fluid communication with the outlet of the fuel control, the heat exchanger, and the inlet to the fuel control such that the fuel recirculated through the conduit receives heat from the electrical generator as it passes through the heat exchanger and transfers heat to the fuel control as the fuel passes through the fuel control to inhibit the formation of ice in the fuel control and to cool the electrical generator.

7. The gas turbine engine of claim 6 which further includes stator vanes and a hydraulic vane controller for positioning stator vanes in the engine, said hydraulic vane controller being in fluid communication with the conduit for recirculating pressurized fuel such that the hydraulic vane controller develops a hydraulic force in response to the flow of pressurized fuel and receives heat from the fuel.

8. The gas turbine engine of claim 6 or claim 7 which includes a filter upstream of the fuel control and wherein the recirculated fuel passes through the filter before entering the fuel control such that heat transferred to the filter blocks the accretion of wax-like paraffin on the filter.