Experimental study of solar drying performance of vegetables with indirect nanofluid heating

In this research, an indirect flow solar dryer of vegetables with indirect heating of nanofluid has been experimentally tested. The system consists of a flat plate solar collector with a water-iron nanofluid working fluid and the dried material is mint vegetable. The time of the experiment was the summer and fall of 1400 at Payam Noor University in Aghajari in the south of Iran. The studies showed that the average efficiency of the collector used is 44.3% and the average thermal efficiency of the dryer is 26.1%. Also, the results obtained from this study in comparison with previous researches provide an acceptable performance in terms of efficiency for dryers with indirect heating. Weather conditions including temperature, humidity and solar radiation were evaluated. According to the data, it was found that the influence of humidity and wind speed was small due to the lack of significant changes and the correlation coefficient was close to 0.3. But in terms of air temperature and solar radiation, with increasing temperature and radiation, the drying stages take place in less time, so that the equilibrium humidity reaches less than 10% in about 5 hours and causes t the dryer efficiency reaches about 29%.