Forced convection adsorption cycles

The convective thermal wave is part of a patented cycle which uses heat transfer intensification to achieve both high efficiency and small size from a solid adsorption cycle. Such cycles normally suffer from low power density because of poor heat transfer through the adsorbent bed. Rather than attempting to heat the bed directly, it is possible to heat the refrigerant gas outside the bed and to circulate it through the bed in order to heat the sorbent. The high surface area of the grains leads to very effective heat transfer with only low levels of parasitic power needed for pumping. The cycle presented here also utilizes a packed bed of inert material to store heat between the adsorption and desorption phases of the cycle. The highest degree of regeneration possible leads to good COP. Thermodynamic modelling, based on measured heat transfer and porosity data, predicts a cycle COP (for a specific carbon) of 0.95 when evaporating at 0 degrees C and condensing at 42 degrees C. These temperatures are compatible with ARI conditions. Further improvement is possible. Experimental heat transfer measurements and cycle simulations are presented which show the potential of the concept to provide the basis of a gas-fired air conditioner in the range 10-100 kW cooling. A research project to build a 10 kW water chiller is underway. The laboratory system, which is being commissioned at the time of writing, is described. (C) 1998 Elsevier Science Ltd. All rights reserved.