AN ITERATIVE ALGORITHM FOR DESIGNING AND SCALING OF PARABOLIC TROUGH COLLECTOR BASED SOLAR AGRO-DRYING SYSTEM

This work proposes a simple and robust iterative algorithm for designing and scaling an indirect solar agro-drying system, which harvests thermal energy for drying using a parabolic trough collector (PTC). Separate computational procedures are developed for the design of the PTC by considering receiver tubes with and without a glass envelope. The computational procedure starts with the total heat requirement in the drying chamber and considers various heat losses and heat loss coefficients for the PTC receiver tube. The equations for various modes of heat losses in receiver tubes with and without a glass envelope are identified and formulated. Using thermal network and heat balance analysis, the expressions for various heat losses and overall heat loss coefficient are formulated in both cases. Required aperture area for the reflector surface of the PTC can be obtained in terms of overall heat loss coefficient and the collector heat removal factor. The tedious equations involved in computational procedure are solved using an iterative algorithm by developing a code in MATLAB. The results obtained from parametric analysis conducted using computational procedure reveals that heat losses and area of PTC required for providing drying thermal energy will be more if the receiver tube of PTC is without glass cover. The iterative algorithm described here can be used to optimize the design parameters and thus helps researchers in designing and sizing the components required for drying agro-based products. The algorithm will also help to scale the size of PTC and drying chamber based on the quantity and item to be dried.