Dynamic heat transfer mechanisms of internal thermal mass: Effects of thermal conductivity and diffusivity under varied temperature conditions
The appropriate use of internal thermal mass in buildings can reduce energy consumption while maintaining thermal comfort. A prerequisite for selecting suitable internal thermal mass is to establish its relationship with indoor air temperature and heat exchange. However, there is currently a lack of...
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Elsevier
2025-01-01
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| Series: | Case Studies in Thermal Engineering |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2214157X24016319 |
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| author | Ru Yang Liting Yuan Dong Zhang Taiquan Wu Yihang Lu |
| author_facet | Ru Yang Liting Yuan Dong Zhang Taiquan Wu Yihang Lu |
| author_sort | Ru Yang |
| collection | DOAJ |
| description | The appropriate use of internal thermal mass in buildings can reduce energy consumption while maintaining thermal comfort. A prerequisite for selecting suitable internal thermal mass is to establish its relationship with indoor air temperature and heat exchange. However, there is currently a lack of analytical models to describe this relationship. This study investigates the dynamic heat transfer performance of internal thermal mass under constant indoor air temperature, exponentially declining temperatures, and sinusoidal heating and cooling conditions. The results show that under constant indoor air temperature, materials with lower thermal conductivity (e.g., plywood with 0.17 W/m·°C) generate more thermal waves and experience faster surface temperature rises compared to materials with higher conductivity (e.g., reinforced concrete with 1.74 W/m·°C). In the case of exponentially declining indoor air temperature, heat exchange per unit area decreases with increasing thickness, with plywood (0.02 m) reaching its peak temperature at 6360 s, and reinforced concrete (0.2 m) at 9900 s. For sinusoidal temperature variations, the decrement factor for plywood and reinforced concrete decreases from 0.90 to 0.59 as thickness increases from 0.02 m to 0.06 m, while the time lag increases from 1.45 h to 3.16 h. The heat exchange is primarily related to the effective thermal capacity per unit area and the storage coefficient, which are determined by the physical properties of the internal thermal mass. These findings provide a quantitative basis for estimating the impact of internal thermal mass on indoor air temperature and heat exchange in the early stages of building design. |
| format | Article |
| id | doaj-art-6a5d1f544b06410a95b79233939dfbd9 |
| institution | Kabale University |
| issn | 2214-157X |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Case Studies in Thermal Engineering |
| spelling | doaj-art-6a5d1f544b06410a95b79233939dfbd92025-01-08T04:52:37ZengElsevierCase Studies in Thermal Engineering2214-157X2025-01-0165105600Dynamic heat transfer mechanisms of internal thermal mass: Effects of thermal conductivity and diffusivity under varied temperature conditionsRu Yang0Liting Yuan1Dong Zhang2Taiquan Wu3Yihang Lu4Nanxun Innovation Institute, Zhejiang University of Water Resources and Electric Power, Hangzhou, 310018, China; The College of Electrical Engineering, Zhejiang University of Water Resources and Electric Power, Hangzhou, 310018, ChinaSchool of Civil Engineering and Architecture, Zhejiang Sci-Tech University, Hangzhou, 310018, ChinaCollege of Mechanical Engineering, Donghua University, Shanghai, 201620, ChinaThe College of Electrical Engineering, Zhejiang University of Water Resources and Electric Power, Hangzhou, 310018, ChinaThe College of Electrical Engineering, Zhejiang University of Water Resources and Electric Power, Hangzhou, 310018, China; Corresponding author.The appropriate use of internal thermal mass in buildings can reduce energy consumption while maintaining thermal comfort. A prerequisite for selecting suitable internal thermal mass is to establish its relationship with indoor air temperature and heat exchange. However, there is currently a lack of analytical models to describe this relationship. This study investigates the dynamic heat transfer performance of internal thermal mass under constant indoor air temperature, exponentially declining temperatures, and sinusoidal heating and cooling conditions. The results show that under constant indoor air temperature, materials with lower thermal conductivity (e.g., plywood with 0.17 W/m·°C) generate more thermal waves and experience faster surface temperature rises compared to materials with higher conductivity (e.g., reinforced concrete with 1.74 W/m·°C). In the case of exponentially declining indoor air temperature, heat exchange per unit area decreases with increasing thickness, with plywood (0.02 m) reaching its peak temperature at 6360 s, and reinforced concrete (0.2 m) at 9900 s. For sinusoidal temperature variations, the decrement factor for plywood and reinforced concrete decreases from 0.90 to 0.59 as thickness increases from 0.02 m to 0.06 m, while the time lag increases from 1.45 h to 3.16 h. The heat exchange is primarily related to the effective thermal capacity per unit area and the storage coefficient, which are determined by the physical properties of the internal thermal mass. These findings provide a quantitative basis for estimating the impact of internal thermal mass on indoor air temperature and heat exchange in the early stages of building design.http://www.sciencedirect.com/science/article/pii/S2214157X24016319Thermal massDynamic heat transferPeriodic heating and coolingStorage coefficientDecrement factorTime lag |
| spellingShingle | Ru Yang Liting Yuan Dong Zhang Taiquan Wu Yihang Lu Dynamic heat transfer mechanisms of internal thermal mass: Effects of thermal conductivity and diffusivity under varied temperature conditions Case Studies in Thermal Engineering Thermal mass Dynamic heat transfer Periodic heating and cooling Storage coefficient Decrement factor Time lag |
| title | Dynamic heat transfer mechanisms of internal thermal mass: Effects of thermal conductivity and diffusivity under varied temperature conditions |
| title_full | Dynamic heat transfer mechanisms of internal thermal mass: Effects of thermal conductivity and diffusivity under varied temperature conditions |
| title_fullStr | Dynamic heat transfer mechanisms of internal thermal mass: Effects of thermal conductivity and diffusivity under varied temperature conditions |
| title_full_unstemmed | Dynamic heat transfer mechanisms of internal thermal mass: Effects of thermal conductivity and diffusivity under varied temperature conditions |
| title_short | Dynamic heat transfer mechanisms of internal thermal mass: Effects of thermal conductivity and diffusivity under varied temperature conditions |
| title_sort | dynamic heat transfer mechanisms of internal thermal mass effects of thermal conductivity and diffusivity under varied temperature conditions |
| topic | Thermal mass Dynamic heat transfer Periodic heating and cooling Storage coefficient Decrement factor Time lag |
| url | http://www.sciencedirect.com/science/article/pii/S2214157X24016319 |
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