The floor heating system with phase change materials (PCMs) for thermal storage is an effective approach to increase the floor thermal capacity and reduce indoor temperature fluctuation range. A two-dimensional numerical model of the floor heating system combined with PCM was developed to investigate its dynamic thermal performance in winter. To verify the reliability of the model, an experimental room was established in Beijing, China. The experiment results agreed well with the modelling results, which demonstrated that the numerical model was reliable. The effects of the phase change temperature, latent heat and thermal conductivity of PCM on the thermal performance of the floor were numerically investigated. The results showed that the phase change temperature and thermal conductivity of PCM had a significant influence on thermal comfort. At the same time, these two thermal physical parameters also played a critical role in improving the utilization rate of PCM. Conversely, the latent heat, in the range of 100 to 200 kJ/kg, had no obvious influence on the thermal performance of the floor. PCM with phase change temperature of 313 K was recommended, which could increase the average indoor temperature by 2.2 K, increase the thermal energy storage ratio by 12% and reduce indoor temperature fluctuation range by 2.2 K.
As an environment-friendly approach for low-grade thermal utilization, adsorption technology has received more and more attention since it can have a plethora of applications, such as thermal energy storage, heat pumps and carbon dioxide capture etc. The performance of this technology is highly affected by the heat and mass transfer efficiency in the adsorption heat exchangers. This minireview is focused on recent studies and investigations on performance improvement of the adsorption heat exchangers, especially on the improvement of the thermal conductivity of adsorbents, the reduction of the thermal contact resistance, and the improvement of the heat exchange area. Discussion on the future research required to improve the heat and mass transfer performance was presented. These technologies and results are expected to provide insights and guidance for performance improvement of both adsorption heat pumps and adsorption thermal energy storage systems.
Titanium silica (TS-1) membrane catalysts grown on the surfaces of spherical substrates can both exploit the high catalytic performance and facilitate their separation from products after the reaction. In this work, a simple static crystallization method was used to perform the in situ construction of a TS-1 membrane on the surfaces of micron-sized spherical carriers. The shortcomings of the TS-1 membrane under static crystallization conditions were overcome by in situ dynamic crystallization, and the effect of rotation speed on the formation of the molecular sieve membrane was investigated. The results showed that the molecular sieve membrane was smooth and homogeneous, with a higher synthesis efficiency at a slow rotational speed. The micron TS-1 spherical membrane catalytic chloropropene epoxidation reaction was investigated in a fixed bed, and the conversion of hydrogen peroxide and selectivity of epichlorohydrin reached 99.4 and 96.8%, respectively. After being reused twice, the catalyst still maintained a stable catalytic performance.
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