A Study on Heat Storage Capacity Performance of Thermochemical Materials

Thermal Energy Storage (TES) is a very important process in the system of energy utilisation on building sectors. It can substantially reduce peak power requirement, and also plays an important role in the utilisation of solar energy and heat recovery. It is necessary to incorporate TES in solar energy and heat recovery systems as there is a temporal mismatch in supply and use of this form of energy. Thermochemical energy storage material is considered as one of the most suitable energy storage adsorbents for building applications, due to its high energy storage density. Adsorbent is a key element of Adsorption Heat Storage (AHS). Harmonizing the adsorbent and AHS cycle can significantly improve storage parameters. In particular, a very specific adsorbent is needed for AHS of low temperature heat (60°C-70°C), huge fluxes of which are usually wasted. For this DECC funded study, Zeolite, Silica Gel and LiNO3 adsorbent materials were investigated using water as working media and an analytical method with FORTRAN programme. The nano-composite materials based on LiNO3/ Zeolite were found to be the most suitable for the heat storage capacity performance as they are able to exchange a large amount water (0.4~0.5 g H2O/g) and have a remarkable heat storage capacity of about 1.15MJ/kg compared with 0.209MJ/kg for water when the temperature change was 50°C.