Feasibility study of producing a carbon/ammonia adsorption high level cold heat energy by heat pump

A multi Adsorption Heat Pump (AHP) system, which can successfully produce high level cold heat energy (253 K) by using waste heat with temperature below 373 K, was proposed in the present study. It consists of an active carbon/ammonia AHP and another AHP such as a silica gel/water AHP, which generates cold heat energy and provides heat sink energy for the active carbon/ammonia AHP, respectively. Considering the performance of ammonia AHP, the adsorption equilibria and adsorption rates of ammonia vapor on several adsorbents were experimentally investigated under 268-303 K. It is found that, (1) compared with other adsorbents, both super active carbon (SAC) and active carbon (AC) have larger reversible adsorptivity at low relative pressure of ammonia vapor; (2) the adsorption rates of ammonia vapor on SAC and AC are much higher than that of water vapor on silica gel; (3) the AHP combined by AC/ammonia as the adsorbent/adsorbate pair can be driven by low temperature heat sources (:! 373 K) with high COP when the heat sink temperature T-M is lower than 283 K.