Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Energy and exergy losses in photovoltaic-thermal module with polymeric heat exchanger
Submission Author:
Bruna de Oliveira Busson , Buscando endereço... , Brazil
Co-Authors:
Bruna de Oliveira Busson, Uallas Henrique de Oliveira de Brito, Victor César Pigozzo Filho, Alexander Leyton Mopan, Júlio Passos
Presenter: Bruna de Oliveira Busson
doi://10.26678/ABCM.COBEM2023.COB2023-0373
Abstract
Photovoltaic-thermal (PVT) modules combine photovoltaic (PV) and solar thermal (ST) concepts. PVT modules improve global energy performance and spatial efficiency for producing electrical energy and hot water in the same area. A new model of the polymeric heat exchanger was installed below the PV module's rear surface, converting it into the PVT module (2.21 m²). Water flows through the heat exchanger parallel channels and removes the heat of the PV module, reducing its operating temperature and improving electrical energy output, because the operating temperature is inversely proportional to conversion efficiency. The main objective of this study is the determination of energy and exergy losses of the PVT module. Energy losses are mainly convection and radiation heat losses occurring in front and rear PVT surfaces. Exergy losses are related to optical losses, heat transfer, and exergy destruction. The optical losses depend on the transmissivity-absorptivity product which, in turn, varies with solar incidence angle. Exergy destruction occurs due to pressure drop for fluid flow through channels and to maximum useful work solar radiation not converted to electrical or thermal energies. One week of measured data between 11:30 and 12:30 hours, hourly of maximum solar incident radiation, is applied to energy and exergy models. On average, electrical and thermal productions were 2.3 kWh and 2.9 kWh, respectively, when the solar irradiation was 4.4 kWh/m²/day. The convection and radiation loss rates fluctuated between 100 and 450 W and 200 to 300 W, respectively, depending on wind velocity and operating cell temperature. However, losses in PVT rear surface were neglected because of the use of thermal insulation. The exergy destruction due to pressure drop and exergy losses due to convection and radiation heat transfers represent about 18%, on average, of total exergy lost. Optical losses are responsible for more than 6% of solar radiation exergy destruction. Some part of exergy destruction not specific evaluated in this work represents about 9.8% on average of total exergy destruction in a PVT module. Moreover, the PVT module is the main component responsible for exergy destruction in a PVT system and electrical and thermal energy conversions are the main contributors to that.
Keywords
PVT module, Energy losses, Exergy losses, Exergy Destruction
