Performance Investigation and Structure Optimization of a Flat Dual-Function Solar Collector

Abstract

The performance of a dual-function solar collector (DFSC) that can work as either water heater or air heater depending on seasonal requirement is investigated via both experimental and numerical approaches in this paper. The numerical results are well consistent with the experimental results. Daily efficiency of the thermosiphon system with DFSC is more than 55% in water heating mode and the instantaneous air heating efficiency of the collector reaches 60%. The effects of inner parameters on the thermal efficiency of the collector are analyzed by numerical simulations of the operation of DFSC in two working modes. It is found that the depths of the two air channels in DFSC have an optimal range suitable for both working modes. The thickness of back insulation should be no less than 0.06 m to prevent heat loss via backboard, and the diameter and number of copper tubes show notable effect on the efficiency of DFSC in water heating mode but slight effect in air heating mode.

Design and Simulation of Air-Solar Preheating Unit: An Improved Design of a Flat Plate Solar Collector

“…The supplementary material contains the partial derivatives or elements of the coefficient matrix in Equation (23). The step by step differentiation that led to each of the thirty-six (36) partial derivatives, which form the simulatory matrices is carefully presented for reader comprehension and scrutiny.…”

“…The design exit fluid temperature (Tf,o) is in good agreement with the reported data by Shemelin and Matuska [2]. Whereas the net power functions; g1(W), g2(W), g3(W), g4(W), g5(W), and g6(W), are 0.0017→0, 0.0015→0, -0.0534→0, 0.0348→0, 0.0081→0 and 0.0043→0, respectively for the design equations; Equations (1), (2), (19), (21), (22) and (23), respectively, are all tending to zero, which substantiate the fact that the simulatory matrices; the coefficient matrix of Equation 23is nonsingular matrices or invertible matrix, which guarantees that the product of the inverse matrix with the column matrix yielded a definite solution (the change in design variables in Equation 25). Then, the change in the variables is added to the previous design variables to obtain new values of the design variables in Equation (26).…”

“…Strategically, Patil and Deshmukh [8], Ma et al [23] recommended a practical insulation thickness of 0.06m for FPSC designs but the present work shall implement Rajput [24] method of establishing a critical insulation thickness. The critical lagging thickness is determined for the unit in order to conserve power as much as possible and to increase its efficiency is considered in developing the base thermal loss equation.…”

Thermal performance investigation of modified flat plate solar collector with dual-function

“…The studies about air-water compound heating that can supply hot air and water simultaneously were not enough. On the other hand, the thickness of the dual-function collectors reached 8~14 cm higher than that of the flat plate liquid solar collector in order to improve the thermal performance [15][16][17], which resulted in a higher cost. The research results are not easy to industrialize due to a long design time and high cost, which were carefully considered by the designer, producer and the potential ender user [19].…”