Development of High-Efficiency Adsorption Heat Exchanger System and Adsorption Heat Pumps

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This study aimed at the realization of freon-free, energy-saving air-conditioning systems with effective waste heat recovery, and utilization of hitherto unexploited near-environmental temperature heat sources in the range between 50 and 80ﾟC.To this end, the silica gel-water adsorption system was investigated, focusing on the suitability to low grade driving heat sources and on efficiency improvement. The research can be broadly divided into two sub-themes, namely a systemic investigation encompassing adsorption cycle simulation and test plant experiments, and an elemental technology study aimed at understanding the adsorption phenomenon on a small scale, inside the adsorbent heat exchanger.(1) Cycle simulation and test plant experiments : The single stage adsorption chiller has a comparatively higher Coefficient Of Performance (COP) , but requires driving heat sources of relatively higher temperature. The three stage chiller, on the other hand, can be driven by heat sources of lower … More temperature, but is limited in terms of maximum possible sink-source temperature lift due to the cycle characteristics. For both single stage and three stage chillers, it was clarified that cooling and hot water inlet temperatures, along with cycle times, are important parameters to be optimized according to the intended application.(2) Adsorption heat exchanger system : It was confirmed that the adsorbent particle diameter and adsorbent bed thickness clearly influence the adsorption characteristics and are important parameters for adsorption efficiency improvement. These characteristics are explained in terms of heat conduction in the adsorbent bed, and the adsorption mechanism was understood. Fin effect on adsorbent bed temperature and concentration distribution was understood from a theoretical analysis with consideration to heat transfer enhancement. It was also clarified that concentration changes are governed by adsorbent void ration and by intraparticle resistance. It was made clear that in adsorbent beds with adsorbent layrs of multiple particle diameters, the discontinuity in vapor flow resistance has a strong influence on adsorption.The following items require further investigation :(a) evaluation of actual machine efficiency improvement, based on knowledge obtained from the cycle simulation ;(b) understanding of both adsorption and desorption phenomena inside the heat exchanger, and optimization of the heat exchanger system. Less