Multiple stream heat exchanger

1. A thermal management system for a gas turbine engine comprising:

a heat exchanger including a first coolant passage for a first coolant medium, a second coolant passage for a second coolant medium that is different than the first coolant medium, a first hot flow passage in thermal communication with the first coolant passage and a second hot flow passage in thermal communication with the second coolant passage all defined within a common housing;

a first valve controlling a flow of a first lubricant into at least one of the first hot flow passage or the second hot flow passage; and

a controller configured to operate the first valve to direct the flow of hot medium into one of the first hot flow passage and the second hot flow passage for transferring thermal energy from the flow of hot medium into one of the first coolant medium and the second coolant medium; and

a secondary cooler for cooling a second lubricant for an integrated drive generator with the first lubricant cooled in the heat exchanger.

2. The thermal management system as recited in claim 1 , wherein a flow of the first coolant medium and a flow of the second cooling medium is counter to a flow of the first lubricant in either the first hot flow passage and the second hot flow passage.

3. The thermal management system as recited in claim 1 , including a bypass passage for routing the first lubricant around the heat exchanger and the first valve controls the flow of the first lubricant through the bypass passage.

4. The thermal management system as recited in claim 3 , including a first temperature sensor communicating information indicative of a temperature of the first lubricant before entering the heat exchanger to the controller, wherein the controller operates the first valve to rout a flow of the first lubricant to at least one of the first hot flow passage, the second hot flow passage and the bypass passage depending upon a temperature of the flow of hot medium.

5. The thermal management system as recited in claim 4 , including a first coolant temperature sensor communicating information indicative of a temperature of the first coolant medium to the controller and a second coolant temperature sensor communicating information indicative of a temperature of the second coolant medium to the controller, wherein the controller operates the first valve to route the first lubricant to a corresponding one of the first coolant passage and the second coolant passage and the bypass passage based on the received information indicative of the temperature of the first coolant medium and the second coolant medium.

6. The thermal management system as recited in claim 2 , wherein the first coolant passage, the second coolant passage, the first hot flow passage and the second hot flow passage are defined in plates that are stackable to alternate the first coolant passage with the first hot flow passage and the second coolant passage with the second hot flow passage.

7. The thermal management system as recited in claim 6 , wherein each of the plates includes internal fins to aid in thermal exchange between the first coolant medium, the second coolant medium and the first lubricant.

8. A gas turbine engine comprising:

a fan disposed within a nacelle;

a core engine disposed within a core cowling, wherein a bypass passage for a fan air stream is defined radially between the nacelle and the core cowl;

a thermal management system for maintaining lubricant for components of the core engine within a defined temperature range, the thermal management system including:

a heat exchanger mounted within the core cowling adjacent the bypass passage, the heat exchanger including a first coolant passage for a hydraulic fluid flow, a second coolant passage for a fuel flow, a first flow passage in thermal communication with the first coolant passage and a second flow passage in thermal communication with the second coolant passage all defined within a common housing;

a first valve controlling a flow of first lubricant into at least one of the first flow passage or the second flow passage;

a controller configured to operate the first valve to direct the flow of first lubricant into one of the first flow passage and the second flow passage for transferring thermal energy from the first lubricant into one of the hydraulic fluid flow and the fuel flow; and

a secondary cooler for cooling a second lubricant for an integrated drive generator with the first lubricant cooled in the heat exchanger.

9. The gas turbine engine as recited in claim 8 , including a bypass passage for routing the first lubricant around the heat exchanger and the first valve controls the flow of the first lubricant through the bypass passage.

10. The gas turbine engine as recited in claim 9 , including a first temperature sensor communicating information indicative of a temperature of the first lubricant before entering the heat exchanger to the controller, wherein the controller operates the first valve to route the flow of the first lubricant to at least one of the first flow passage, the second flow passage and the bypass passage depending upon a temperature of the flow of first lubricant.

11. The gas turbine engine as recited in claim 10 , including a hydraulic fluid temperature sensor communicating information indicative of a temperature of the hydraulic fluid flow and a fuel temperature sensor communicating information indicative of a temperature of the fuel to the controller, wherein the controller operates the first valve to route the first lubricant to a corresponding one of the first coolant passage, the second coolant passage and the bypass passage based on the received information indicative of the temperature of the hydraulic fluid flow and the fuel flow to control a temperature of the first lubricant.

12. The gas turbine engine as recited in claim 11 , wherein the first coolant passage, the second coolant passage, the first flow passage and the second flow passage are defined in plates that are stackable to alternate the first coolant passage with the first flow passage and the second coolant passage with the second flow passage.

13. The gas turbine engine as recited in claim 12 , wherein each of the plates includes internal fins to aid in thermal exchange between the hydraulic fluid, the fuel and the lubricant.

14. A method of managing thermal properties of a lubricant flow for a gas turbine engine, the method comprising:

assembling a heat exchanger to include a first coolant passage for a hydraulic fluid flow, a second coolant passage for a fuel flow, a first flow passage in thermal communication with the first coolant passage and a second flow passage in thermal communication with the second coolant passage all defined within a common housing;

measuring a temperature of the hydraulic fluid flow, the fuel flow and the lubricant flow with at least one sensor assembly and communicated the measured temperature information to a controller; and

operating at least one valve to rout lubricant flow into thermal communication with one of the hydraulic fluid flow in the first coolant passage and fuel flow in the second coolant passages to maintain the lubricant flow within a predefined temperature range; and

routing a portion of lubricant flow exiting the heat exchanger to a secondary cooler for cooling a second lubricant low for an integrated drive generator.

15. The method as recited in claim 14 , wherein the at least one valve proportionally routes the lubricant flow into each of the first coolant passage and the second coolant passage depending on the measured temperature of the hydraulic fluid flow, the fuel flow and the lubricant flow.

16. The method as recited in claim 14 , including assembling the heat exchanger into a core cowling adjacent a fan air stream bypass passage.