Thermal analysis of novel minichannel-based solar flat-plate collector

• A novel flat-plat solar collector was thermally analyzed.
• A computer program to predict the thermal performance of the novel collector was developed.
• Thermal and hydraulic characteristics of the mini-scaled conduits was numerically modeled.
• Experimental test was conducted in order to validate the analytical model.

This paper investigates thermal performance of a new design of minichannel-based solar flat-plate collector. The solar collector consists of an array of minichannels located in the absorber plate which is covered by single glass cover. Water was used as the working fluid. A numerical model was implemented to determine the heat transfer characteristics and pressure drop of the working fluid inside the minichannels. The numerical model was verified by comparing the predicated results with those obtained from the available analytical and experimental data with maximum deviation of 10%. A program code was developed using Engineering Equation Solver EES software in order to predict the thermal performance of the novel solar collector at any operating conditions. The code is based on energy balance and heat transfer equations assuming a quasi-steady state condition. A small-scale of this novel solar collector, with an absorber plate area of 0.6 m2, is experimentally tested during month of June in Beirut. The experimental test was conducted aiming to validate the computer program in terms of the calculation of the instantaneous efficiency and overall heat loss coefficient. There was a good agreement between the analytical and experimental results with a maximum deviation of less than 10% for instantaneous efficiency and 20.4% for predication of overall heat loss coefficient. The thermal and hydraulic performance of the proposed novel collector was compared to that of the conventional flat-plate solar collector. The comparison revealed that the heat removal factor of the novel collector is higher than that of the conventional one by 16.1%. Effect of varying mass flow rate of the working fluid on the new collector's thermal and hydraulic performance has been also studied.