Thermal analysis of a mini solar pond of small surface area while extracting heat from lower convective layer

Abstract

Solar energy is major renewable energy resource which can potentially fulfill 100% energy demand of the world while releasing no polluting agents to the atmosphere in contrast to the conventional fossil fuels. However, due to its intermittent nature, solar energy requires effective storage of energy for utilizing during the night and cloudy weather. A solar pond is a promising solution because it has its own energy storage which is suitable for low temperature application like building heating and cooling. This paper presents a thermal analysis of a salt gradient solar pond while extracting heat from the lower convective zone. A mathematical model of surface area is developed. Efficiency analysis is performed numerically using a MATLAB code for steady temperature difference of 30 °C as well as 20 °C across the gradient layer for three different pond sizes of depths 1.5 m, 1.0 m, and 0.5 m. The thermal efficiency of first pond of 1.5 m depth varies from around 21% in summer to 11% in winter. Thermal efficiency of solar pond drops significantly by reducing its size and non-convective zone thickness. Annual average efficiencies are 21%, 19%, and 9.5% for the three ponds of 1.5 m, 1.0 m, and 0.5 m depths, respectively. So it is recommended to prefer a pond of 1.5 m over others. However, the efficiency of smaller the pond can be significantly improved by compromising on quality the of thermal energy, efficiency of 0.5 m pond rises to 17% when operating at temperature just 20 °C above ambient, compared with 9.5% for 30 °C above ambient. Solar pond therefore proves to be suitable for effectively utilizing solar energy and can present an effective solution for low temperature energy needs like space heating.

Advances in solar pond technology and prospects of efficiency improvement methods

“…The temperature gradient is another crucial aspect of a solar pond, managed through the varying salinity levels from the pond's surface to the bottom (Shahid et al, 2023). This gradient prevents the upward convection of heat, which would otherwise cause the heat collected at the bottom layer to quickly dissipate to the cooler surface layer, reducing the overall efficiency of the solar pond (Shah et al, 2017). On the other hand, higher temperatures, especially at the top convective layer, can lead to increased heat losses due to evaporation or radiation, which can decrease the overall efficiency of the solar pond as the stored heat energy is lost to the environment (Andrews & Akbarzadeh, 2005).…”

Solar Power for Households in Iraq

“…Concentrated Power Stations (CPS) use a series of mirrors and lenses to concentrate large area of sunlight into a small area which is connected to an electrical power generator. Other large scale, solar ponds have been considered in Iraq by several authors such as (Shah et al, 2017). These technologies operate by using a pool of very saline water that prevent convection and thus support accumulation of thermal heat in lower areas.…”

“…These technologies operate by using a pool of very saline water that prevent convection and thus support accumulation of thermal heat in lower areas. Despite ideal temperature conditions in Iraq for this technology, Shah et al (2017) documented that the dusty environment is detrimental to the efficiency of such systems and therefore limits the applications. Similarly with solar chimneys which regularate temperature in buildings, however suffer from issues with dust accumulation (Chaichan, 2011).…”

Thermal, environmental, and cost analysis of effective solar portable vaccine refrigerator by COMSOL Multiphysics

“…Paz et al 17 improved a computational programming software to predict the polluting processes using dynamic mesh model. Shah et al 18 performed a numerical thermal analysis using a MATLAB code for steady temperature difference to evaluate the efficiency of a mini‐solar model.…”