An apparatus to facilitate a start-up operation of a combined cycle or rankine cycle power plant is provided and includes a plurality of heat pipes, each of which respectively includes a first portion in thermal communication with exhaust emitted from a heat source and a second portion in thermal communication with the first portion, a cooling unit to cool the second portions of the heat pipes, and a controller which is configured to control the cooling unit to cool the second portions of the heat pipes and to thereby remove heat from exhaust via the first portions of the heat pipes.