FORCED-CONVECTION ADSORPTION CYCLES

The convective thermal wave is part of a patented cycle which uses hea t transfer intensification to achieve both high efficiency and small s ize from a solid adsorption cycle. Such cycles normally suffer from lo w power density because of poor heat transfer through the adsorbent be d. Rather than attempting to heat the bed directly, it is possible to heat the refrigerant gas outside the bed and to circulate it through t he bed in order to heat the sorbent. The high surface area of the grai ns leads to very effective heat transfer with only low levels of paras itic power needed for pumping. The cycle presented here also utilizes a packed bed of inert material to store heat between the adsorption an d desorption phases of the cycle. The highest degree of regeneration p ossible 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 d egrees C. These temperatures are compatible with ARI conditions. Furth er improvement is possible. Experimental heat transfer measurements an d cycle simulations are presented which show the potential of the conc ept to provide the basis of a gas-fired air conditioner in the range 1 0-100 kW cooling. A research project to build a 10 kW water chiller is underway. The laboratory system, which is being commissioned at the t ime of writing, is described. (C) 1998 Elsevier Science Ltd. All right s reserved.