Forced convection adsorption cycle with packed bed heat regeneration

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 new cycle presented here also utilises a packed bed of inert material to store heat between the adsorption and desorption phases of the cycle, The high degree of regeneration possible leads to good coefficients of performance (COPs). Thermodynamic modelling, based on measured heat transfer data, predicts a COP (for a specific carbon) of 0.90 when evaporating at 5 degrees C and condensing at 40 degrees C, with a generating temperature of 200 degrees C and a modest system regenerator effectiveness of 0.8. 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 IO-kW water chiller is underway. The laboratory system, which should be operational by June 1997, is described. (C) 1998 Published by Elsevier Science Ltd and IIR. All rights reserved.