Thermal conductivity and contact resistance of mesoporous silica gel adsorbents bound with polyvinylpyrrolidone in contact with a metallic substrate for adsorption cooling system applications

Comparative study on adsorbent characteristics for adsorption thermal energy storage system

“…More extensive local temperature variation with zeolites are relevant with a smaller magnitude of thermal conductivity. The thermal conductivities of zeolites are almost half of silica gel thermal conductivity . Another difference in adsorption characteristics between adsorbents is the duration of the adsorption process.…”

“…The object of the vapor transfer tube installed at the center of the reactor is to improve the vapor transfer capability within the reactor. The double copper coil is part of the water circulation loop and was made by rolling a 6.35-mm-diameter copper tube doubly to improve the adsorption heat recovery, which is poor due to the low thermal conductivity of the adsorption materials packed in the reactor, for example silica gel <0.4 W/m-K, zeolite 13X, or zeolite 4A < 0.2 W/m-K [19,20,21].…”

“…The thermal conductivities of zeolites are almost half of silica gel thermal conductivity. [20][21][22] Another difference in adsorption characteristics between adsorbents is the duration of the adsorption process. It is longest in a test with silica gel and the shortest with zeolite 4A.…”

Improving the Energy Efficiency of Adsorption Chillers by Intensifying Thermal Management Systems in Sorbent Beds

“…Factors such as particle size and the packing density could have significantly affected the effective thermal conductivity. From the summarized thermal conductivity packed bed of dry silica gel reported in the literature [15], the values range from 0.106 to 0.198 W/m K. Comparing the reported values with the expected effective thermal conductivity of 0.147 W/m K, a maximum discrepancy of 27.8% can be attributed.…”

“…The remaining thermal resistances were determined by the dimensions of the heat exchanger, the thermal conductivity of the aluminum and silica gel, and the thermal contact resistance between the aluminum and the silica gel. The thermal contact resistance between silica gel and aluminum was taken to be 2.0 m 2 K/kW based on the work of Sharafian et al [15] and Zhu and Wang [16] who investigated the contact resistance between different granular sorbents and copper to range between 0.83 and 2.55 m 2 K/kW. The effective thermal conductivity of the silica gel powder was [3] Granular HX Silica gel/water 3.7 0.5 26 45 [10] Coated HX Consolidated activated carbon/ammonia 9 0.22 800 1 [11] Coated HX Zeolite/methanol 3 0.11 25 18 [12] Coated HX Zeolite/water 6 0.24 675 5 [12] Granular HX Zeolite/water 1.96 0.4 498 5 Transactions of the ASME made to be 0.147 W/m K based on averaging the effective thermal conductivity from the literature as summarized in the work of Freni et al [17] and Sharafian et al [15].…”