Gravitational heat pipes for discontinuous applications

Gravitational heat pipes or thermosiphons (TS) are simple and efficient heat exchangers. This paper deals with the adaptation of these exchangers to discontinuous or cyclic processes such as chemical heat pumps. Such TS must fulfil a two-mode working too: the TS working must be active/inactive according to the successive endothermal/exothermal phases of the cyclic process. Two kinds of TS blockage processes have been successfully experimented: they act either on the liquid or on the vapor phase inside the TS. A simple model demonstrates that realistic configurations of TS and reactor can easily reduce the energy and duration required by the blockage process itself on the performances of the coupling.