A heat pipe heat exchanger (2) and a heat pipe (10) therefor wherein the condensor end (30) of the heat pipe (10) is provided with a hydrogen gas collection chamber (80) which houses a hydrogen gas oxidization material (85) and/or has a wall portion formed at least in part of a material (82) through which hydrogen gas diffuses thereby improving the removal of hydrogen gas generated within the heat pipe (10) from the working cavity (50) thereof.
The heat exchanger (2) includes a casing (4) defining a first gas duct (6) for a stream of heated gas and a second gas duct (8) for a stream of gas to be heated. The heat pipes (10) are disposed within the heat exchanger (2) with their evaporator portion (20) in the first gas duct (6) and their condenser portion (30) in the second gas duct (8). An auxiliary plenum chamber (40) is provided laterally adjacent the second gas duct (8) to receive the hydrogen gas collection chamber (80) of each heat pipe. The hydrogen gas collection chambers (80) are selectively heated either by a heating coil (90) wrapped about the hydrogen gas collection chamber (80) of each heat pipe, or by heating the interior of the auxiliary plenum chamber (40).