Heat transfer analysis and structure optimization of unit of flat plate based on a response surface test: An experimental teaching perspective in higher education

Abstract

The Flat Plate is a common component of solar photothermal experiment and an important teaching tool in the new energy teaching experiment. Aiming at the problem of low heat transfer efficiency and poor teaching effect of traditional roll-bond flat plate, this paper conducts a numerical simulation study on the flow and heat transfer characteristics in the ”Y” -shaped channel unit. The four parameters of width, length, runner parting angle and runner width are used as control variables to optimize the heat transfer structure of the runner. Taking the ”Y” -shaped channel unit as the research object, the finite element model of conjugate heat transfer was established by using Fluent. Through numerical simulation analysis, it is concluded that in the defined length and width interval, the thermal efficiency increases first and then decreases with the increase of the length of the heat transfer unit, and the pressure drop coefficient has a negative correlation with the length and width of the unit. The runner width has a positive correlation with the thermal efficiency and a negative correlation with the pressure drop coefficient. Then, according to the Box-Behnken principle, a response surface test for heat transfer optimization was designed, an optimization model with thermal efficiency and pressure drop coefficient as the response indicators was established, and the optimal element design scheme was determined. The optimization results show that when the subunit length of the heat transfer runner is 40 mm, the width is 35 mm, the parting angle is 60°, and the runner width is 11 mm, the thermal efficiency of the ”Y”-shaped runner is 0.782, and the pressure drop coefficient is 0.121. Finally, a direct-expansion solar auxiliary heating system is built to test the scheme. The experimental results show that the collector using the ”Y”-shaped channel shows better solar energy utilization, which increases the COP of the system by 15.2%. This study provides a reference for the design and optimization of other types of flow channels to improve the heat transfer efficiency of the roll-bond flat plate. Through optimization, the system has innovated in the experimental mode, effectively made up for the shortcomings in the training of new energy professionals, and enriched and developed the experimental theory system and teaching methods of higher education of energy and power majors.