Study on the Thermal Performance of Inner and Outer Wall Surfaces Based on FDM-ATSCM
ObjectiveThis study examines the limitations of traditional heat conduction models in terms of accuracy and computational efficiency. Such models often struggle to handle dynamic wall temperature variations driven by solar radiation, ambient temperature, humidity, and wind speed. Many existing appro...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Editorial Department of Journal of Sichuan University (Engineering Science Edition)
2025-01-01
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| Series: | 工程科学与技术 |
| Subjects: | |
| Online Access: | http://jsuese.scu.edu.cn/thesisDetails#10.12454/j.jsuese.202401042 |
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| Summary: | ObjectiveThis study examines the limitations of traditional heat conduction models in terms of accuracy and computational efficiency. Such models often struggle to handle dynamic wall temperature variations driven by solar radiation, ambient temperature, humidity, and wind speed. Many existing approaches rely on overly simplified assumptions, resulting in significant errors and inefficient strategies. For large-scale or high-performance buildings, even slight temperature deviations can have major impacts on energy consumption and indoor conditions. Accordingly, this study proposes the FDM-ATSCM model to enhance the numerical accuracy of wall surface temperature analysis while improving computational efficiency.MethodsTraditional finite difference methods (FDM) can accurately capture heat transfer in walls by discretizing the partial differential equations of conduction. However, when the temporal or spatial resolution is high, the computational load increases significantly, making practical applications challenging. To balance computational accuracy and efficiency, this study introduces an Adaptive Time-Step Control Method (ATSCM) into the traditional FDM framework. Under rapidly changing meteorological conditions, the time step is automatically reduced to maintain high accuracy, whereas in relatively stable conditions, the time step is increased to save computing resources. On this basis, a Seasonal Auto-Regressive Integrated Moving Average with Exogenous Regressors (SARIMAX) model is employed to fully capture the temporal effects of solar radiation, wind speed, and relative humidity on wall temperature. The effects of outdoor climate factors—solar irradiance, wind speed, outdoor temperature, and humidity—on the thermal conductivity and specific heat capacity of wall materials are also included to ensure a sound representation of wall heat transfer. By setting appropriate thresholds, the model identifies whether each meteorological factor causes significant changes in heat transfer, ultimately striking a balance between computational efficiency and accuracy.Results and Discussions To validate the effectiveness of the FDM-ATSCM method, we conducted experimental comparisons under identical conditions between wall surface temperatures predicted by FDM-ATSCM, actual onsite measurements, and results from EnergyPlus. These tests confirmed that FDM-ATSCM can accurately capture wall surface temperatures under combined climatic influences while using fewer computational resources. Experimental results demonstrated strong agreement between the simulated and measured temperatures, especially during periods of rapidly changing weather, indicating the adaptive time-step approach effectively captures sudden meteorological shifts.ConclusionsAnalysis of the results shows that solar radiation is the most significant factor affecting the exterior wall temperature, with only a minor influence when below 50 W/m². Meanwhile, wind speeds below 4 m/s have a limited impact on the exterior wall temperature, and relative humidity in the 30%–60% range can generally be disregarded. The exterior wall temperature exerts a strong influence on the interior wall temperature through heat conduction. Given the complexity of indoor environments, omitting long-wave radiation on the interior wall surface helps improve the accuracy of interior wall temperature predictions, as reflected by an increase in the R² value from 0.887 to 0.938 when this factor is excluded. Moreover, relative humidity not only alters the heat transfer coefficient of the exterior wall surface but also affects the thermal conductivity of the wall materials, thereby influencing the interior wall temperature. Consequently, when humidity exceeds 60%, its effect on the interior wall temperature becomes slightly greater than its effect on the exterior wall temperature. In contrast, wind speed and atmospheric pressure mainly affect the interior wall temperature indirectly by modifying the exterior wall temperature, rather than acting directly on the interior surface, and thus can be considered negligible in terms of their direct impact on interior wall temperature. |
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| ISSN: | 2096-3246 |