Numerical Analysis of a TEG and mPCM Enhancement System for BIPVs Using CFD

Abstract

Building-integrated photovoltaics (BIPVs) are the most promising systems for net-zero energy buildings. However, there are few practical cases because of shortcomings, such as the lack of solar tracking and the rapid rise in PV surface temperature. Therefore, methods of increasing the efficiency of BIPVs have been proposed and studied. These include using phase change material (PCM) or heat fins, wavelength selection, decreasing the PV surface temperature, or using a thermoelectric generator (TEG) and convection cooling to utilize the waste heat from the PV. Many preceding studies have been conducted on TEG and convection heat dissipation methods to utilize as much waste heat as possible. Therefore, in this study, a TEG–PCM hybrid system using mPCM was proposed to improve constructability. Herein, the appropriate phase change temperature of the PCM, the heat fin spacing in the PCM container, and the TEG arrangement were analyzed through computational fluid dynamics (CFD)-based simulations. The appropriate melting temperature of the PCM, the heat fin interval, and the arrangement of the TEG for the proposed system are 25 °C, 20 mm, and 140 mm, respectively. In order to achieve optimal efficiency, it is necessary to consider an appropriate amount of heat transfer, and it has been confirmed that if there are too many thermoelectric elements, the opposite effect occurs.

Latest Advancements in Solar Photovoltaic‐Thermoelectric Conversion Technologies: Thermal Energy Storage Using Phase Change Materials, Machine Learning, and 4E Analyses

“…The normal PCM is a liquid-state PCM with tiny particles. As a result, it results in leakage issues and external environment reactivity [86,87]. When packaging is disregarded, leakage happens after prolonged usage, and if a casing flaw exists, leakage can happen extremely quickly.…”

“…The organic or inorganic materials can enclose PCM droplets smaller than 1000 μm due to the design of the microencapsulation phase change material (mPCM). Hence, by increasing the PCM's surface-to-volume ratio and covering the liquid PCM surface, it is possible to overcome the drawbacks of the standard PCM, including its diminished thermal conductivity and challenges related to leakage [87][88][89][90][91]. A study by Royo et al [85] constructed their proposed BIPV-TEG-PCM system (Figure 7), which employs phase change material encapsulated at the microscale (mPCM) to capture lost solar and thermal energy from the building envelope, the best design for manufacturing was determined using numerical analysis.…”