Study on non-isothermal reaction and sintering kinetics of Ca(OH)2 particle cluster dehydration with temperature distribution modification

•Non-isothermal reaction and sintering of Ca(OH)2 particle cluster was studied.•Temperature distribution and variation on particle cluster suface was analyzed.•Particle cluster shrinkage was found to relate sintering behavior and heating rate.•Interaction mechanism between dehydration, temperature and sintering was revealed. Dehydration, microstructure evolution, and sintering behaviors of Ca(OH)2 particles are essential to the application of thermochemical energy storage technology. The current study established a method that combined the high-temperature stage with visualization and online temperature measurement technologies to investigate the non-isothermal reaction and sintering kinetics of Ca(OH)2 particle cluster dehydration. The results showed that three stages can be obtained from the thermogravimetric measuring curves of the dehydration process for both AR-Ca(OH)2 and I-Ca(OH)2 samples. The non-isothermal reaction kinetic parameters were calculated with the F-W-O method and compared with different heating rates. Temperature was found to be heterogeneously distributed on the particle cluster surface with a maximum difference of 50 ℃ during the dehydration process while the reaction front absorbed heat and reduced the temperature. Ca(OH)2 particle cluster shrank during the heating process and the shrinkage ratio increased with the temperature. Low heating rate was found to cause a higher shrinkage ratio of Ca(OH)2 particle cluster, which was up to 8 % after the dehydration reaction ended. Agglomerates appeared between particles when the temperature was 300 ℃ with pores found inside the particle cluster, and the size increased with the heating rate, while the sintering neck was found inside the particle cluster at 600 ℃. Finally, with the modification of the measured temperature on the particle cluster surface, the sintering kinetics of the Ca(OH)2 particle cluster were analyzed, and the interaction mechanism between dehydration, temperature and sintering was revealed.