Effective thermal conductivity and permeability of compact compound ammoniated salts in the adsorption/desorption process
Effective thermal conductivity and permeability of compact compound ammoniated salts in the adsorption/desorption process
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DOI：
10.1016/j.ijthermalsci.2013.03.017
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发表时间：
2013-09
影响因子：
4.5
通讯作者：
Long Jiang;Liwei Wang;Z. Jin;Ruzhu Wang;Y. Dai
中科院分区：
文献类型：
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作者：
Long Jiang;Liwei Wang;Z. Jin;Ruzhu Wang;Y. Dai
对于卤化盐-氨工作对，由于络合和分解过程中的溶胀和团聚现象，导热系数和渗透率总是随着吸附/解吸浓度的变化而变化。相应地，影响吸附制冷性能的传热传质性能也会受到影响。为了提供上述过程的概述，开发了以膨胀天然石墨(ENG)为基质的固化复合吸附剂，用于8种不同的盐。研究了三种不同比例的ENG和盐在氨化过程中的导热系数和渗透率。将得到的数据与不吸附氨的吸附剂的数据进行了比较。结果表明，氨化盐的导热系数和渗透率与复合吸附剂的盐比和固结密度有很强的依赖关系。对于未吸附的吸附剂，当含盐量为75%时，CaCl2-ENG的最佳热导率为1.73W/(m·K)，密度为550×10~3/m~3。当含盐量为83%时，BaCl2-ENG的最佳渗透率为9.02W×10−11m~2，密度为450g/m~3。此外，致密的复合氨化盐的导热系数和渗透率随氨浓度的不同而显著不同。在吸附过程中，导热系数的最大增幅高达1.25W/(m·−)，而渗透率的最大降幅高达5.08W/(m·K)，不同吸附状态下的磁导率最大降幅达5.08W/(m·K)。不同吸附工质对的热导率为0.62W/(m·K)~2.98W/(m·K)，磁导率为1.47W/(m·K)~8.13W×−11m2。
For halide salt-ammonia working pairs, thermal conductivity and permeability always change with the adsorption/desorption concentration because of swelling and agglomeration phenomena during the processes of complexation and decomposition. Correspondingly, heat and mass transfer performance, which both affect the adsorption refrigeration performance, will be influenced. To provide an overview of the process mentioned above, solidified composite adsorbents that utilize expanded natural graphite (ENG) as the matrix were developed for eight different salts. Thermal conductivity and permeability were investigated for three different ratios between ENG and salt in the ammoniating process. The resulting data were compared with the data for the adsorbents that did not adsorb ammonia. The results indicate that the thermal conductivity and permeability of ammoniated salts have a strong dependence on the salt ratio and the consolidated density of the compound adsorbent. In regard to the adsorbent that was not adsorbed, the optimal thermal conductivity was 1.73 W/(m K) for the adsorbent of CaCl2-ENG with a density of 550 kg/m3when the salt ratio was 75%. The optimal permeability was 9.02 × 10−11m2for the adsorbent of BaCl2-ENG with a density of 450 kg/m3when the salt ratio was 83% in converging mode. Furthermore, the thermal conductivity and permeability of the compact compound ammoniated salts varied significantly with different concentrations of ammonia. The largest increase in thermal conductivity was as high as 1.25 W/(m K)during the adsorption process, whereas the largest decrease in permeability was as high as 5.08 × 10−11m2for different adsorption states. For the different adsorption working pairs, the thermal conductivity and permeability ranged from 0.62 to 2.98 W/(m K) and 1.47 × 10−14–8.13 × 10−11m2, respectively.