Scientists from South Ural State University (SUSU) have patented a desalination device that can utilize low-grade heat sources for distilling seawater and purifying ground water. Indonesian colleagues have proposed a method to optimize its operation.
For over a decade, joint research by Russian and Indonesian scientists in solar energy has focused on improving the efficiency of photovoltaic converters (solar panels or solar modules).
"The main issue with solar photovoltaic panels is that during normal operation under direct sunlight, their surface heats up significantly, releasing so-called waste (non-utilizable) heat into the environment," explains Evgeny Solomin, professor at the Department of Electric Power Stations, Grids, and Power Supply Systems at SUSU. "This directly contributes to global warming – the waste heat output is comparable to 60-80% of the module's total electrical power. Moreover, when heated to 50-60°C, the solar module's efficiency drops from 18-22% to 3-10% due to a decline in its current-voltage characteristics."
Three years ago, scientists at South Ural State University became the first in the world to propose an innovative method of removing heat from the surface of solar panels to heat and subsequently utilize this heat for distilling seawater and mineral-rich groundwater. As part of a project supported by the Russian Science Foundation, the Chelyabinsk researchers developed an experimental prototype of a high-speed seawater distiller operating under low pressure, which uses heat from the solar module's surface. Initially, the scientists employed a conventional coiled heat exchanger in the distiller design, which had significant thermal losses. As a result, the source water had to be additionally heated by an optional heat pump before distillation.
Indonesian scientists from the Sepuluh Nopember Institute of Technology (ITS), intrigued by their Chelyabinsk colleagues' development, managed to improve the heat exchanger's design by replacing the conventional coil with a jet-based heat removal system. This method splits the heat flow into parallel jets.
The new design proposed by the Indonesian team, featuring a reflector in the form of a jet plate, achieved a dual effect: cooling the photovoltaic panels while simultaneously reflecting light to optimize energy absorption and heat transfer through the heat exchanger. Under the coordination of the Russian project team, the Indonesian partners conducted a comprehensive performance analysis of the system, including energy output and detailed techno-economic and eco-economic assessments.
The results of computational fluid dynamics (CFD) simulations confirmed the experiments. The solar module's surface temperature decreased from 64°C to 30-48°C (depending on the operating mode), while overall efficiency increased from 3-10% to 6-17%, respectively.
This collaborative approach extends the lifespan of photovoltaic modules by 2.5 times and increases electricity production by 3-5 times (in sunny weather and in a hot climate). It also reduces waste heat emissions into the atmosphere, thereby mitigating contributions to global warming. Additionally, the Indonesian team's proposed upgrade to the Chelyabinsk scientists' unique desalination unit optimizes the distillation of seawater and groundwater using this system.
In the coming years, the Chelyabinsk developers plan to present a serial prototype of the desalination device powered by low-grade heat sources. This will not only enable mass production but also significantly increase the chances of widespread adoption of the technology.