Heat Exchanger with Controlled Coefficient of Thermal Expansion
The heat exchanger with a controlled coefficient of thermal expansion (CTE) includes a low CTE thermal expansion control member operatively connected to a heat transfer member in order to restrain the lateral thermal expansion of the heat transfer member during use. The thermal expansion control member is placed outside the heat transfer path, so the thermal expansion control member can be made of a low thermal conductivity material without increasing the thermal resistance of the heat exchanger. The CTE of the thermal expansion control member is lower than that of the heat transfer member, so as to constrain lateral thermal expansion of the heat transfer member during operation. The difference between the CTE of the device being cooled and the heat transfer member, i.e. the CTE mismatch, is reduced over conventional heat exchangers by restraining the heat transfer member during operation.
1 . A heat exchanger for cooling a heat producing device, the heat exchanger comprising:
a heat transfer member having a first surface operatively connected to the heat producing device, a second surface opposite the first surface, at least the first surface of the heat transfer member having a coefficient of thermal expansion larger than the coefficient of thermal expansion of the heat producing device;
a thermal expansion control member operatively connected to the second surface of the heat transfer member such that the thermal expansion control member is outside of a heat transfer path disposed between the heat transfer member and the heat producing device, the thermal expansion control member having a coefficient of thermal expansion sufficiently lower than that of the heat transfer member so as to constrain lateral thermal expansion of the heat transfer member during use; and
wherein during operation of the heat producing device, the thermal expansion control member constrains the lateral thermal expansion of the heat transfer member so that the heat transfer member expands a similar amount as the expansion of the heat producing device, allowing a rigid connection between the heat producing device and the heat transfer member without inducing excessive thermal stresses in the heat producing device or at the interface between the heat producing device and the heat transfer member.
2 . The heat exchanger according to claim 1 , wherein the coefficient of thermal expansion for the heat producing device is in the range of about 3-6 ppm.
3 . The heat exchanger according to claim 2 , wherein the coefficient of thermal expansion for the heat transfer member is above about 15 ppm.
4 . The heat exchanger according to claim 1 , wherein the thermal expansion control member includes a restraining plate.
5 . The heat exchanger according to claim 4 , wherein the thermal expansion control member further includes a manifold, the manifold being constructed and arranged to distribute and collect fluid over a heat transfer surface of the heat transfer member.
6 . The heat exchanger according to claim 5 , further comprising a bow compensation member.
7 . The heat exchanger according to claim 6 , wherein the bow compensation member is disposed adjacent the manifold on a side opposite that of the restraining plate.
8 . The heat exchanger according to claim 4 , further including a compliant manifold constructed and arranged to distribute and collect fluid over a heat transfer surface of the heat transfer member and a bow compensation member disposed between the compliant manifold and the thermal expansion control member.
9 . The heat exchanger according to claim 4 , further including a rigid manifold constructed and arranged to distribute and collect fluid over a heat transfer surface of the heat transfer member, a compliant gasket disposed between the rigid manifold and the thermal expansion control member, and further including a bow compensation member disposed between the compliant gasket and the thermal expansion control member.
10 . The heat exchanger according to claim 5 , wherein the thermal expansion control member further includes a second restraining plate and wherein the manifold is disposed between the restraining plate and the second restraining plate.