Gas turbine engine thermal management system

1. A gas turbine engine, comprising:

a primary function oil circulation system configured to circulate oil;

a primary function fuel circulation system configured to circulate fuel; and

a thermal management system comprising a fluid circuit configured to circulate thermally neutral heat transfer fluid, a first heat exchanger disposed on the fluid circuit, a second heat exchanger disposed on the fluid circuit, and a third heat exchanger disposed on the fluid circuit;

wherein the thermal management system is configured to exchange heat with both the oil of the primary function oil circulation system and the fuel of the primary function fuel circulation system using the thermally neutral heat transfer fluid;

wherein:

the first heat exchanger comprises an air to heat transfer fluid heat exchanger configured to transfer heat between air and the thermally neutral heat transfer fluid;

the second heat exchanger comprises a heat transfer fluid to oil heat exchanger configured to transfer heat between the thermally neutral heat transfer fluid and the oil; and

the third heat exchanger comprises a heat transfer fluid to fuel heat exchanger configured to transfer heat between the thermally neutral heat transfer fluid and the fuel.

2. The gas turbine engine of claim 1 , wherein the first heat exchanger, the second heat exchanger, and the third heat exchanger are arranged in series on the fluid circuit.

3. The gas turbine engine of claim 1 , wherein the first heat exchanger is disposed between the second heat exchanger and the third heat exchanger such that the thermally neutral heat transfer fluid flows through the first heat exchanger in order to pass from one of the second heat exchanger and the third heat exchanger to the other of the second heat exchanger and the third heat exchanger.

4. A method of transferring heat in a gas turbine engine, comprising

circulating a thermally neutral heat transfer fluid in a fluid circuit of a thermal management system, wherein a first heat exchanger is disposed on the fluid circuit and a second heat exchanger is also disposed on the fluid circuit;

transferring heat between a first engine fluid and the thermally neutral heat transfer fluid at the second heat exchanger; and

transferring heat between the thermally neutral heat transfer fluid and air at the first heat exchanger;

wherein the second heat exchanger is disposed adjacent to a primary function engine fluid circulation system for the first engine fluid; and

wherein the primary function engine fluid circulation system performs an engine function using the first engine fluid independent of the step of transferring heat between the first engine fluid and the thermally neutral heat transfer fluid at the second heat exchanger such that the primary function engine fluid circulation system comprises a direct route to a portion of the gas turbine engine in which the first engine fluid is configured to perform the engine function of the primary function engine fluid circulation system.

5. The method of claim 4 , wherein a third heat exchanger is disposed on the fluid circuit, wherein the method further comprises:

transferring heat between the thermally neutral heat transfer fluid and a second engine fluid at the third heat exchanger.

6. The method of claim 4 , further comprising:

varying the flow rate of the thermally neutral heat transfer fluid in the fluid circuit.

7. The method of claim 4 , wherein the first engine fluid is oil.

8. The method of claim 4 , wherein the first engine fluid is fuel.

9. A thermal management system, comprising:

a thermally neutral heat transfer fluid circuit;

a first heat exchanger disposed on the fluid circuit; and

a heat transfer fluid to fuel heat exchanger disposed on the fluid circuit, wherein the heat transfer fluid to fuel heat exchanger is disposed adjacent to a primary function fuel circulation system such that heat transfer fluid is configured to thermally communicate with fuel in a fuel flow pathway of the primary function fuel circulation system, wherein the primary function fuel circulation system is configured to perform a fuel function independent of the thermal management system, wherein the fuel flow pathway of the primary function fuel circulation system is a direct route to a portion of an engine in which the fuel is configured to perform the fuel function of the primary fuel circulation system.