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Xu, Weijie (2024) Influence of the pavement solar collector system on the urban environment. PhD thesis, University of Nottingham.

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Abstract

The Urban Heat Island (UHI) phenomenon has been a concern for many cities worldwide, and it is getting more severe with the development of urbanisation. Asphalt can absorb a large amount of heat due to its high heat capacity, and excessive heat will be released into the air, aggravating the UHI effect. The cool pavements showed a higher potential than other heat mitigation methods in resolving the urban overheating issue. Pavement Solar Collector (PSC) is a system that allows excessive heat to be transferred from the pavement surface to the bottom layers and then absorbed by the circulating fluid in the copper pipes; the absorbed heat can be converted into passive thermal energy, stored in the thermal reservoir and utilised for other purposes.

This study evaluated the performance of the PSC system in the urban environment, it also investigated the impact of the PSC system on the urban microclimate and the building’s energy performance by carrying out transient simulations. The Computational Fluid Dynamics (CFD) tool – ANSYS Fluent and Building Energy Simulation (BES) tool – IES (Integrated Environmental Solutions) VE (Virtual Environment) were used for numerical simulations; in total, three CFD models and one BES model were developed in this study.

Based on the observations from previous work, this research first conducted a feasibility study on the cooling effect of the PSC system in the urban environment by combining the PSC domain and the urban canyon domain in the same model. It is confirmed that the PSC system can cool down the air temperature effectively and has the potential to mitigate the UHI phenomenon; therefore, the research further investigated the performance of the PSC system in the urban canyon and its impact on the urban microclimate and building energy demand over a period of time.

The maximum temperature of the pavement surface decreased from 55.49℃ to 45.80℃ by implementing the PSC system under the set conditions. The performance of the PSC system was affected by the circulating flow rate, temperature, operation period and urban configurations. The turbulent flow with low temperature and velocity reduced the pavement temperature more effectively. Extending the system operation period is necessary to dissipate the stored heat in the asphalt pavement. In the neighbourhood-scale model, the PSC system cooled down the pavement surface up to 5.31℃. From the ground-floor height to the third-floor height, the air temperature reduction by the PSC system dropped from 0.83℃ to 0.50℃. The larger urban street aspect ratio resulted in a higher air temperature, and the percentage of air temperature reduction caused by the PSC system was slightly higher. By implementing the PSC system, the whole building’s cooling energy demand was reduced by 3.24%; the cooling load reduction at night was much higher than during the daytime. Therefore, using the PSC system for UHI mitigation in urban areas with abundant sunshine and high building densities is practical.

Item Type:	Thesis (University of Nottingham only) (PhD)
Supervisors:	Wood, Christopher Calautit, John Wu, Yupeng
Keywords:	Urban heat island; Heat mitigation; Pavements; Urban environment; Solar collectors
Subjects:	T Technology > TE Highway engineering. Roads and pavements
Faculties/Schools:	UK Campuses > Faculty of Engineering > Built Environment
Item ID:	78566
Depositing User:	Xu, Weijie
Date Deposited:	31 Dec 2024 04:40
Last Modified:	31 Dec 2024 04:40
URI:	https://eprints.nottingham.ac.uk/id/eprint/78566

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