Investigation on thermal conductive consolidated composite CaCl2 for adsorption refrigeration

Abstract

Properties such as thermal conductivity, permeability, adsorption concentration of adsorbents are paramount for adsorption refrigeration. A novel consolidated composite CaCl2 with the matrix of expanded natural graphite treated with sulfuric acid (ENG–TSA) was investigated and the samples were developed according to different mass ratio of salt and different density. Results indicate that samples have very perspective heat and mass transfer performance. The highest thermal conductivity was 88.1 W/(m K), which is 22 times higher than that with the matrix of expanded natural graphite (ENG) and 400 times higher than ordinary granular CaCl2. Permeability of adsorbent was between 9.31 × 10−10 to 3.05 × 10−14 m2 while the density ranged between 300 and 500 kg/m3. Adsorption performance of composite CaCl2 was tested, and the results showed that for the samples with different density and salt mass ratio adsorption quantity ranged between 0.364 g/g to 0.4492 g/g while the cooling temperature and evaporating temperature changed from 25 to 35 °C and −10 to 15 °C, respectively. Furthermore, under the conditions of same heat source, cooling water and evaporating temperature, the heating time for the tube adsorber of composite CaCl2 with ENG–TSA as the matrix was almost 2.5 times less than that with ENG as the matrix.