INVESTIGATION ON SENSIBLE AND LATENT HEAT SOLAR THERMAL ENERGY STORAGE

Abstract

Energy is an important segment for the advancement of today’s world and major requirement of the world is fulfilled by fossil fuels. However, the use of fossil fuels is associated with some major drawbacks such as limited quantity, global warming and pollution. Therefore, experts are emphasizing to use the renewable sources of energy as these are available in plenty and capable to fulfil the global energy demand. Solar energy is one of the renewable energy source that can be a major support in energy sector. Solar energy can be used with solar photovoltaic systems and solar thermal energy systems. Due to discontinuous behaviour of solar energy, both types of systems requires integration of energy storage unit for their efficient utility. There are various solar thermal energy storage (TES) systems that can be used to store the thermal energy during its availability and provide it during the requirement. The solar TES systems are generally used in residential and domestic buildings as well as various applications of industry and the stored heat can be used for heating or cooling application and power generation. The use of phase change material (PCMs) seems to be very promising technology for TES and the designing of the PCM encapsulation is one of the major parameter for the performance enhancement of PCM enabled TES system. Therefore, the detailed investigation on solar thermal energy storage system based on combined sensible-latent heat is necessary. Under the present work, the TES technologies and its classification with material properties are the main focus. Basic principle of sensible heat based storage systems such as water tank storage, underground storage system, packed-bed storage system is discussed in the thesis. A brief review of latent heat storage system based on phase change material (PCM) and their use in various application like space heating, cooling in buildings, solar water heating, solar dryer, heat pump system is also presented. Based on the literature review, it is found that the maximum researchers of solar thermal energy storage have reported their studies on the parameters related to sensible heat and very few studies are reported on the performance affecting parameters related to latent heat. In order to obtain the effect of latent heat related parameters on the performance of solar thermal energy storage systems, an analyses of coaxial component for both melting and solidification using PCM RT35 is carried out under the present thesis. In the analysis, the investigation and comparative i study is carried out in a simplified manner with the help of two-dimensional model. In the considered model, one is horizontally oriented shell-tube heat exchanger, whereas, the second one is vertically oriented. The numerical investigation is carried out in computational fluid dynamics approach in Ansys Fluent software tool through four unique models. The present study may be useful for the researchers and manufacturers working on the solar thermal energy storage system.