Aircraft precooler heat exchanger

1. A heat exchanger comprising:

a first member having an inlet at a first end and a first flange at an opposite end, the first member being generally hollow to define a first flow path between the inlet and the first flange, the first member being made from a nickel-chromium material; and

a second member having a second flange at an end, the second flange being directly coupled to the first flange, the second member further having an outlet on a second end opposite the second flange, the second member being generally hollow to define a second flow path in series with the first flow path and arranged between the second flange and the outlet, the second member being made from titanium.

2. The heat exchanger of claim 1 wherein the first member includes a first outer surface with a plurality of first fins disposed thereon.

3. The heat exchanger of claim 2 wherein the second member includes a second outer surface with a plurality of second fins disposed thereon.

4. The heat exchanger of claim 3 wherein the second member is made from commercially pure titanium.

5. The heat exchanger of claim 3 wherein the first member has a length equal to or greater than 60% of the total length of the first member and second member.

6. A heat exchanger system for an aircraft having an engine having a fan stage and a compressor stage, the heat exchanger system comprising:

a first conduit configured to receive bleed air from the compressor stage;

an environmental control system; and

a precooler heat exchanger comprising:

a first member having a rectangular outer surface and having an inlet at a first end fluidly coupled to the first conduit, the first member having a first flange on an end opposite the first end, the first member being made from a nickel-chromium material, the first member configured to reduce a temperature of the bleed air from an inlet temperature to less than 830° F. at the first flange; and

a second member having a rectangular outer surface and fluidly coupled in series to the first member, the second member having an outlet fluidly coupled to the environmental control system, the second member having a second flange arranged on an end opposite the outlet and directly coupled to the first flange the second member being made from titanium, the second member configured to reduce the temperature of the bleed air to 465° F. at the outlet.

7. The heat exchanger system of claim 6 further comprising a second conduit configured to receive air from the fan stage at a third end and flow the air across the first member and second member in parallel.

8. The heat exchanger system of claim 7 wherein the first member includes a first outer surface with a plurality of first fins disposed thereon.

9. The heat exchanger system of claim 8 wherein the second member includes a second outer surface with a plurality of second fins disposed thereon.

10. The heat exchanger system of claim 9 wherein the second conduit is arranged to flow the air across the plurality of first fins and the plurality of second fins.

11. The heat exchanger system of claim 10 wherein the second member is made from commercially pure titanium.

12. The heat exchanger system of claim 10 wherein the second member is made from a titanium alloy.

13. A method of cooling air for an aircraft environmental system, the method comprising:

providing a first member having an inlet at a first end and a first flange at an opposite end, the first member being made from a nickel-chromium material; and

providing a second member fluidly coupled in series to the first member by a second flange, the second member further having an outlet on a second end, the second member being made from titanium;

wherein the first member is configured to receive air at a first temperature at 1058° F. and cool the air to a second temperature of less than 830° F. at a flange at an opposite end of the flange and the second member is configured to cool the air to a third temperature of 465° F. at the outlet.

14. The method of claim 13 further comprising flowing air in parallel across the first member and the second member.

15. The method of claim 14 further comprising providing a plurality of first fins disposed on a first outer surface of the first member.

16. The method of claim 15 further comprising providing a plurality of second fins disposed on a second outer surface of the second member.

17. The method of claim 16 wherein the second member is made from commercially pure titanium.

18. The method of claim 13 wherein the second member is configured to receive air at the second temperature and cool the air to the third temperature of less than 465° F. at the outlet.