Performance evaluation and parametric analysis of an integrated diurnal and nocturnal cooling system driven by photovoltaic-thermal collectors with switchable film insulation. (15th February 2022)

• Record Type: Journal Article
• Authors: Chen, Hongkai; Li, Zeyu; Sun, Bin
• Is Part Of: Energy conversion and management. Volume 254(2022)
• Publication Date: 2022-02-15
• Subjects: Photovoltaic thermal collector -- Solar cooling -- Sky cooling -- Radiative cooling -- Absorption chiller; Direct energy conversion -- Periodicals; Energy storage -- Periodicals; Energy transfer -- Periodicals; Énergie -- Conversion directe -- Périodiques; Direct energy conversion; Periodicals; 621.3105
• DOI: 10.1016/j.enconman.2021.115197
• Languages: English
• ISSNs: 0196-8904

Abstract

Highlights: PVT collector switches between diurnal and nocturnal modes by inflating/deflating. Glazed, unglazed and switchable collectors are compared based on annual simulation. Using switchable film insulation can improve annual total energy yield by 10–32%. Film transmittance has opposite effects on diurnal and nocturnal cool energy yield. Low photovoltaic panel emissivity is favorable for annual total electricity saving. Abstract: Cooling systems integrated with photovoltaic-thermal (PVT) collectors are promising for reducing building energy consumption because PVT collectors can provide photovoltaic power generation, solar thermal cooling, and nocturnal passive cooling. Glazed and unglazed PVT collectors have typically been used in previous studies, but they lead to conflicting goals for enhancing the all-day energy performance. Glazed collectors are favorable for solar thermal cooling but result in low nocturnal passive cooling capacity, while unglazed collectors exhibit the opposite behavior. In this study, PVT collectors with switchable film insulation (i.e., PVTfilm collectors) are introduced to drive an integrated diurnal and nocturnal cooling system. Such collectors can adapt to daytime and nighttime operating modes by inflating and deflating their air cushion. Annual (8760-hour) simulations were performed based on the case study of a tropical building. Three system layouts driven by different PVT collectors were compared. The effects of key optical parameters on energy performance were analyzed. The results show that the PVTfilm collectors combine satisfactory solar thermal cooling and nocturnal passive cooling performances, with an annual total energy yield that is 10% and 32% higher than those of glazed and unglazed PVT collectors, respectively. To improve the annual total electricity savings, it is advantageous to increase the film transmittance for solar radiation, decrease the film transmittance for long-wave thermal radiation and decrease the photovoltaic panel emissivity for long-wave thermal radiation. This work is relevant for PVT systems to improve the all-day energy performance and reduce building energy consumption.