Experimental Study and Performance Enhancement of a Novel Micro Heat Pipe Pv/T System in a Cold Region

Abstract

The photovoltaic/thermal (PV/T) system, which harnesses solar energy to produce both electricity and thermal energy, holds substantial potential in China's northwest region, an area with abundant solar irradiation. To demonstrate the performance of micro heat pipe (MHP) PV/T, this paper conducted typical day experiments on MHP-PV/T system based on the working fluid R141b inside the MHP in four seasons in Lanzhou, which included environmental temperature, surface temperature of the PV/T panel, back temperature of the PV/T panel, water tank temperature, thermal collection efficiency (PCE) and power conversion efficiency (TCE). The PCE was the highest with 12.64% in winter, and the TCE was the highest with 39.45% in summer. Additionally, using R141b as the working fluid has increased the average TCE by 7.14% and the average PCE by 4.46% compared to acetone, demonstrating that R141b had better performance for system performance. A three-dimensional mathematical model of PV/T panel was developed and validated with experimental results. The simulation results aligned well with the experiment data. It was observed that the double-layer glass lowered the solar transmittance while simultaneously reducing the convective heat transfer between the PV/T panel and its surrounding environment, leading to an increasing temperature of the solar cell, subsequently causing a decline in the PCE and a rise in the TCE of the MHP-PV/T. Additionally, the nanofluid within the airfoil heat exchanger lessened the thermal resistance between the fluid and the airfoil heat exchanger, resulting in an elevated temperature of the nanofluid and enhanced performance of the MHP-PV/T.

Keywords: micro heat pipe PV/T, double-layer glass, nanofluid, PCE, TCE