A more efficient device in energy transfer for a cool thermal discharge system has been designed. The governing equations have been derived from ice melting with specified heat fluxes on the boundary of complete removal of melt, and the approximation solutions were obtained, from the integral boundary-layer analysis, to estimate the thickness of ice melted and the thermal penetration distance in the ice-layer region. Considerable improvement in performance of cool thermal discharge can be achieved if the operation is conducted with complete removal of melt, rather than without removal of melt.