新型复合吸附剂传热性能的强化

Heat Transfer Enhancement of a New Composite Adsorbent

以氯化钙和杉木屑为原料,通过炭化活化的方法制备具有发达孔隙结构的吸附剂,然后加入膨胀石墨以强化吸附剂的传热性能。石墨的含量从0%到50%变化,通过氨吸附性能实验考察石墨含量对吸附量和吸附速率的影响。实验结果表明,在四个小时内,复合吸附剂对氨气的吸附量随着膨胀石墨含量的增加而减小,吸附速率随膨胀石墨含量的增加先增加后减小,而导热系数随膨胀石墨含量的增加单调的增加。对吸附制冷而言,膨胀石墨含量为30%的复合吸附剂具有最佳性能,其导热系数达到0.193W/(m.K),吸附时间为15min时对应的吸附量达到0.431g/g。

Composite adsorbents of CaCI2/activated carbon were prepared by charring and activating at high temperature from CaC12 and fir crumbs. Thermal conductivity was improved by adding expanded graphite into composite adsorbent. The proportion of expanded graph- ite in composite adsorbents was changed from 0% to 50%. The effect of the proportion of expanded graphite in composite adsorbents on the uptake and the adsorption rate was observed from ammonia adsorption experiment. It is found that the adsorption capacity of composite absorbent is decreasing all the time while the adsorption rate increasing at first but then decreasing with the increase of the proportion of expanded graphite. It is also found that thermal conductivity of the composite adsorbent is improving with the increase of the proportion of expanded graphite. When the proportion of expanded graphite in composite adsorbent is 30%, the composite adsorbent has the optimum performance for adsorption refrigeration--its thermal conductivity of the composite adsorbent is 0. 193 W/（ m. K） and its uptake is 0.43 1g/ g in first 15min of the adsorption time.