What Is a Renewable Energy Sources?

A renewable energy source plays a vital role in the future existing applications such as solar energy, geothermal heat. In the development of the energy in the heat transferring applications, the thermal conductivity plays a vital role. For the development of the energy efficient usages, the convection heat transfer can be preferred by changing the flow geometry. More attention has been focussed for the utilization of the thermal energy storage. The energy storage is of the three types that are latent heat, sensible heat, and thermo chemical heat.

Sensible Heat Storage Systems: It means that no change of state but a transfer of heat takes place. The most common material to store the heat is the water due to low costs.

Latent Heat Storage Systems: It is used the storage capacity of a material’s phase change.

The performance of different types of heat exchangers and heat storages used as latent heat thermal energy storage units has investigated by many researches. zalba [1],[2] have reviewed various kinds of PCMS, Phase change materials (PCMs) with their phenomenal phase changing behaviour hold a key for many developments in renewable energy and engineering systems for sustainable future.
PCM which can store and release heat energy over a temperature range has become an eminent candidate for many engineering applications that includes thermal, civil, electronics and textile[3], Nanofluids are suspensions of nanoparticles in base fluids, a new challenge for thermal sciences provided by nanotechnology.
Nanofluids have unique features different from conventional solid-liquid mixtures in which mm or ?m sized particles of metals and non-metals are dispersed. It has been shown that nanoparticles with higher thermal conductivity than their surrounding liquid can increase the effective thermal conductivity of suspension[4], since the thermal conductivity of the solids are typically higher than that of liquids, by suspending nano or larged sized particles in fluids, the thermal conductivity is increased[5].
A lot of research has been going on the thermal energy storage such as sensible heat and latent heat. Of this latent heat storage systems have more advantageous so the materials containing latent heat principle was used for the heat energy storage applications. Thermal energy storage system was used to store the heat in the PCM for the charging process. Phase Changing Materials(PCM) with their heat storage and releasing behaviour have found suitable for latent heat storage systems that can be operated at wide range of temperatures. PCM’s are Latent heat storage system place an important role in energy conservation of environmental conditions.
Latent heat storage system having a high thermal conductivity when compared with the sensible heat storage system. Phases changing materials are those which is used to observe heat and release heat even to the surroundings temperature High storage density and heat charging process at constant temperature. These systems are preferable to store the high energy in terms of latent heat and sensible heat. Nanofluids are a fluid containing nanometer size called nanoparticles. As the nanoparticles having the more thermal conductivity, nanoparticles are used to increase the heat transfer rate for the PCM within the less period of time so