Numerical Simulation of Heat Transfer Characteristics for Optimum Air Flow Rate in Triangular PV/T System

Abstract

The aim of this numerical study is to investigate the heat transfer characteristics of the air flowing in the triangular photovoltaic thermal (PV/T) array/system at variable velocities. The PV/T array in the present analysis is composed of seven photovoltaic (PV) panels connected in series along with a triangular duct throughout its length. The heat transfer analysis in the PV panel (solid component) and visualization of temperature distribution in the PV/T system has been simulated by the use of system coupling of steady state thermal and CFX tools in ANSYS 18.2. Experiment was initially performed at velocity of 1.5 m/s inside the duct by the use of ANSYS software to predict the glass temperature, outlet air temperature, and tedlar temperature of triangular PV/T system. Further, the velocity has been incremented by 1 m/s up to 6.5 m/s to see the overall performance of the system. The validation of simulation results showed a good agreement with the experimental results under reasonable limit. The gain in temperature with the increase in velocity becomes marginal (only 7%) after 4.5 m/s. The temperature contours from the numerical simulation also revealed that cooling up to the last panel is not significant beyond 4.5 m/s. Similar tendency is documented in the overall exergy efficiency which significantly increased to 4.5 m/s and became marginal with further increment in velocity. It can be inferred that the optimum velocity which can fulfill the requirement of cooling of all PV panels along with reasonable thermal output is 4.5 m/s. The thermal energy gain gradually increases as the day progresses and becomes maximum at 2:00 PM. The average thermal energy gain being 9.6% higher than that in the morning (10:00 AM) indicates its suitability for applications requiring moderately high temperature. The present numerical investigation focuses on improving the overall performance of the system without the involvement of any additional cost. The system can be used in various applications like crop drying, space heating, etc. Owing to different outlet air temperatures during the day, the applications can either be utilized independently or can be combined to be used at different times according to the temperature requirement.