History of the solar ponds: A review study

Solar pond was discovered as a natural phenomena around the turn of the last century in the Medve Lake in Transylvania in Hungary. In this lake, temperatures up to 70 °C were recorded at a depth of 1.32 m at the end of the summer season. The minimal temperature was 26 °C during early spring. The bottom of this lake had a salt NaCl with concentration of 26 percent. Solar pond is artificially constructed. To prevent convection, salt water is used in the pond. Those ponds are called "salt gradient solar pond". Nowadays, mini solar ponds are also being constructed for various thermal applications. It was concluded that the optimum value of salinity in the mini solar pond is 80 g/kg of water.Solar pond Salt gradient solar pond Mini solar pond Heat extraction

Thermal performance investigation of double pass-finned plate solar air heater

In this paper, the double pass-finned plate solar air heater was investigated theoretically and experimentally. An analytical model for the air heater was presented. Numerical calculations had been performed under Tanta (latitude, 30° 47'N and longitude, 31°E) prevailing weather conditions. The theoretical predictions indicated that the agreement with the measured performance is fairly good. Comparisons between the measured outlet temperatures of flowing air, temperature of the absorber plate and output power of the double pass-finned and v-corrugated plate solar air heaters were also presented. The effect of mass flow rates of air on pressure drop, thermal and thermohydraulic efficiencies of the double pass-finned and v-corrugated plate solar air heaters were also investigated. The results showed that the double pass v-corrugated plate solar air heater is 9.3-11.9% more efficient compared to the double pass-finned plate solar air heater. It was also indicated that the peak values of the thermohydraulic efficiencies of the double pass-finned and v-corrugated plate solar air heaters were obtained when the mass flow rates of the flowing air equal 0.0125 and 0.0225 kg/s, respectively.Solar air heaters Double pass Fins Thermal performance Thermohydraulic efficiency