STUDY OF HEAT TRANSFER CHARACTERISTICS OF A SENSIBLE HEAT STORAGE FOR SOLAR THERMAL ENERGY

Abstract

The rapid evolution of Renewable Energy Sources (RESs) during the last two decades resulted in the installation of many renewable energy power systems all over the world such as small hydro, wind, solar, biomass based etc. One of these resources is solar radiation which can be converted directly into electricity by using solar photovoltaic (PV) panels or converted into heat by solar power concentrators. Solar thermal power plants, often also called Concentrating Solar Power (CSP) plants, produce electricity in much the same way as conventional thermal power stations. The difference is that they obtain their energy input by concentrating solar radiation and converting it to high-temperature steam or gas to drive a turbine or motor engine. The sun, unlike the other forms of green energy, is not available during the night time hours. Although renewable, its source is not continual 24 hours a day, which is the primary need for ways to store solar energy. Various types of solar thermal storage medium available to fulfill the demand of continuous supply of electricity are molten salts, steam accumulators, oils, concrete, liquid ions, graphite, phase change materials. In sensible heat storage systems, energy is stored or extracted by heating or cooling a liquid or a solid, which does not change its phase during this process. Very little work has been reported on sensible heat storage of solid material to store the heat. Therefore there is a need to study of heat transfer characteristics of sensible heat storage for solar energy. A experimental set up is designed and fabricated in order to study transient heat transfer characteristics of concrete structure. Characteristics of sensible heat storage have been investigated theoretically and by CFD analysis. Experimental and simulation results are validated and they are found to be in a good agreement. It is recommended that this work can be further be extended to study heat transfer characteristics of sensible heat storage at higher temperature range with different composition of concrete having embedded metal fins.