Experimental Evaluation of Thermals Performances of The Solar Dryer with Parabolic Trough Collector

Abstract

A cylindrical-parabolic solar-thermal converter, with 0.5m2 of capture surface, was manufactured and attached to a furnace, constituting an indirect solar dryer. Thermal balances of the elements of the receiver, housed in the focal point of this collector, are settled. A campaign of vacuum tests of this dryer indicated temperatures of the heat-bearing air in natural convection, along the absorber tube (70°C) and inside the drying cage (almost 60°C,on average). The average thermal efficiency of said converter has been evaluated at 50%.The higher the efficiency, the less the converter's capture surface is required and, therefore, less investment is required. These promising results testify to the effective performance of this new dryer compared to dryers with flat collectors, whose efficiencies could not exceed 40% despite the large surface area of these collectors.

Experimentation of the Solar Dryer with Parabolic Trough : Drying of Okra

“…Therefore, the indirect solar dryer, with a solarthermal converter, cylindrical-parabolic as an air insolator, seems to be a viable technical-economic compromise, avoiding the cost of improving the thermal performance of a flat plate collector, an alternative to the low energy density of the incident solar radiation [5] and finally, a good response to the problem previously mentioned [4]. To confirm this conclusion, tests related to the drying of okra were conducted.…”

“…Compared to the literature, we have the data grouped in Table 4. The differences could be justified either by the drying conditions; some of them are done with the help of microwave, or by the effect of temperature which influences the drying [13][14], or related to the thickness of the sample [15][16][17], to the varieties of okra, to the type of drying equipment used, globally to the operating conditions and other uncontrolled parameters.…”