Experimental studies of the efficiency of a solar system, including a passive water heater and an active seawater distiller

In the hot climate of the Mangistau region, located on the eastern coast of the Caspian, there are no sources of freshwater. Of the available groundwater deposits, only three are suitable for drinking water supply. The scarcity is felt in remote areas and coastal areas, where the population uses groundwater. The provision of the population is carried out by a seawater desalination plant. In the hot summer period, due to high temperatures, the productivity of desalination plants decreases (the water in the channels reaches 30 °C, and the plants are designed for 20 °C). This factor provides opportunities for the development of desalination plants using this heliopotential. Easy to manufacture, environmentally and economically viable solar desalination plants are essential for coastal areas where water is scarce. The article presents the results of experimental studies of the heliosystem, which consists of a passive solar water heater (SWH) and an active solar desalination plant (SW). Water is heated in the SWH pool and supplied to the lower SW pool-1, in which the desalination process is achieved by cooling the water pool-2. By reducing the temperature in the SW volume, the condensation temperature is reached. The coating of 2 layers of glass with an air gap reduces heat losses and raises the temperature in the installations by 10–12 °C and keeps it at night. Horizontal glass coverings provide a large area for solar radiation to enter the pool surface. Heat transfer by convection, in the volume between the "cold" and "hot" basins, is determined using the convection coefficient, which depends on the product of the numbers Gr and Pr. According to the results of experiments, the daily productivity of the desalter was 1.97, 1.83 and 2.31 l/m(2) on the day of July 20, 21 and 22, 2019. The maximum value of the total heat transfer coefficient for SVN was 32.9 W/m(2) °C, for SW 49.4 W/m(2) °C.