Development of new algebraic derivations to analyze minichannel solar flat plate collectors with small and large size minichannels and performance evaluation study

Abstract

In this study two new simple methods are extended for thermal performance evaluation of minichannel collectors. The classical fin analysis method is employed for minichannel collectors with small size and small distanced minichannels and the concept of overall heat loss coefficient is utilized for minichannel collectors with any minichannel size and any distance between them. After verification, the new derivations are used to evaluate the performances of minichannel collectors with small and large size minichannels. For every mass flow rate the energy efficiencies of both minichannel collectors are found approximately the same, but much better than that of a conventional collector. For mass flow rate of 0.02 kg/s, the thermal efficiencies of the minichannel collectors compared to that of a conventional collector are 14.22% and 13.83% higher, respectively. Considering higher and identical thermal performances of the minichannel collectors compared with that of the conventional collector and the superiority of hydraulic performance of the minichannel collector with large size minichannels, design and commercialization of minichannel collectors with large size minichannels are recommended. Development of a new general relation for minichannel collector efficiency factor attained in this study paves the way for future research and simple performance evaluation of minichannel collectors.