Heat storage performance analysis of ZMS-Porous media/CaCl2/MgSO4 composite thermochemical heat storage materials

• Published in: Solar energy materials and solar cells Vol. 230; p. 111246
• Main Authors: Xueling, Zhang, Feifei, Wang, Qi, Zhang, Xudong, Lei, Yanling, Wang, Yeqiang, Zhang, Chuanxiao, Cheng, Tingxiang, Jin
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.09.2021; Elsevier BV
• Subjects: Adsorption; Adsorption capacity; Calcium chloride; Calorimetry; Cold pressing; Composite materials; Desorption; Differential scanning calorimetry; Heat; Heat storage; Heat storage density; Heat transfer; Hygroscopicity; Low temperature; Magnesium sulfate; Mass transfer; Molecular sieves; Porous media; Salts; Shelf life; Stability; Storage systems; Thermal conductivity; Thermochemical heat storage; Porous media; Adsorption capacity; Heat storage density; Thermochemical heat storage; Stability
• DOI: 10.1016/j.solmat.2021.111246
• ISSN: 0927-0248

A new composite thermochemical heat storage (TcHS) material was proposed herein with good heat storage performance and desirable stability, which was prepared by using solid-state cold pressing with a zeolite molecular sieve (ZMS) and two salts (CaCl2 and MgSO4). First, the optimized mass content (CaCl2:MgSO4 = 6:4) denoted Smix was obtained, which represents an equilibrium between the adsorption capacity and deliquescence. Then, two types of ZMS porous media: 13X and NaY were added to Smix to further prevent deliquescence and improve stability, respectively. An orthogonal experiment with four factors (mass fraction, pressure, temperature, and humidity) and three levels was used to test the optimal preparation conditions, and the optimal configurations were obtained for Xopt (13X-ZMS: CaCl2: MgSO4 = 10: 54: 36) and Yopt (NaY-ZMS: CaCl2: MgSO4 = 20: 48: 32). The optimized samples were measured by SEM, XRD and thermal conductivity tests, and the adsorption capacities for Smix, Xopt, and Yopt were found to follow the order of Xopt (0.449 g/g) > Smix (0.374 g/g) > Yopt (0.335 g/g). The accumulated void formation for the porous media can promote heat and mass transfer and can significantly improve the adsorption capacity and avoid deliquescence. Differential scanning calorimetry (DSC) results showed that the heat storage density (HSD) for Xopt (1414.49 J/g) is higher than that for Yopt (1097.02 J/g). Finally, 20 cycles showed that Xopt has good cycle stability based on the normalized ad/desorption mass (>1) and normalized desorption heat (>0.8). The results showed that Xopt shows application potential as a TcHS composite material in medium- and low-temperature thermochemical adsorption heat storage systems. •A new composite Thermochemical heat storage (TcHS) material has been synthesized by solid-state cold pressing using zeolite molecular sieve (ZMS) and two salts (CaCl2 and MgSO4).•The adsorption capacity of Smix (CaCl2:MgSO4 = 6:4), Xopt (13X-ZMS:CaCl2:MgSO4 = 10:54:36) and Yopt (NaY-ZMS:CaCl2:MgSO4 = 20:48:32) are 0.374, 0.449 and 0.335 g/g, respectively, both the Xopt and Yopt were avoided the deliquesce of the Smix.•The heat storage density of Smix, Xopt and Yopt were determined to be 1886, 1414.5 and 1097 J/g, respectively.•The Xopt has the best cycle stability in the 20 cycles from the normalized ad/desorption mass (>1) and the normalized desorption heat (>0.8) than the Yopt and Smix.