Solar ponds have a horizontal surface, and therefore, the solar radiation received per unit area is less as compared to what is received on the surface normal to solar radiation. In addition to this, once the solar pond is constructed it cannot supply increased demand of thermal energy, if need arises. These two limitations of the solar pond can be overcome by the use of planar reflectors. These reflectors reflect the solar radiation, and hence, increase the radiation input to the solar pond. As a result, the pond not only supplies more heat energy but also saves on land cost to provide the same amount of energy. The enhancement of the average radiation gain in a solar pond using planar reflector has been studied and calculated for Indore city in India. The results are then compared with the performance of the pond without reflector.

Salt gradient solar pond is a water body in which a significant temperature rise is caused by the absorption of solar radiation by the prevention of convection. In other words, solar ponds are solar radiation collector-cum-storage devices. These are capable enough to supply low grade heat at large scale. There are three distinct zones in a solar pond, namely an Upper Convective Zone (UCZ), a Non-Convective Zone or Non-Convective Gradient Zone (NCZ or NGZ) and a Storage or Lower Convective Zone (STZ or LCZ).

The top convective layer absorbs a large portion of the solar radiation. However, less than 50% penetrates to a depth of 0.2 m (Wang and Akbarzadeh, 1983) as half the solar spectrum is in the infra red region, for which water is almost opaque (Cengel and Ozissik, 1984). In other words, water is a selective absorber. In the same context, Mehmet et al. (2006) have also reported a maximum absorption of 28.1% in the heat storage zone. Various losses of this stored energy result in further reduced efficiency. Different methods and models have been proposed to improve the efficiency of the solar pond (Rajagopan et al., 2008; and Sharma et al., 2009).

Mechanical Engineering Journal, Solar Pond, Upper Convective Zone, Non-Convective Gradient Zone, Lower Convective Zone, Radiation Transmission, Incident Radiations, Operational Feasibility, Economic Feasibility, Ambient Temperature Variation, Salt Gradient Solar Pond, Solar Radiation.