[New Paper] Thermal performance analysis of an existing building heating based on a novel active phase change heater

Latent heat thermal energy storage (LHTES) can store energy in a narrow temperature range. Usually solid–liquid phase change is used, by melting and solidification of a material. Upon melting heat is transferred to the material, storing large amounts of heat at constant temperature; the heat is released when the material solidifies. They are characterized by a dense storage capacity. Active applications of PCM achieve a fast switching between thermal energy storage and release, in response to the demand of building energy consumption. Whereas, there are few studies concerned dynamic response relationship between indoor thermal environment and transient thermal and mass performance of LHTES applied in buildings. Therefore, the aim of this investigation is to assess the capacity of the active phase change heater and the related thermal performance of buildings from the aspect of energy conservation. The entire internal space is assumed as an isothermal domain with the transient mean temperature marked as the performance index.

Abstract: An active phase change heater is configurated to transform excess electricity at off-peak tariff periods into thermal energy, store and release it at the electricity on-peak tariff periods to accomplish heating demand towards an existing building with marine climate. A reliable numerical model is developed based on phase change heat transfer and convective heat transfer between phase change material (PCM) and indoor air. The objective temperature zone (18—24 °C) is achieved using an event control that is coupled with a heat transfer model. The performance of indoor temperature, phase change characteristics, and operating model of active phase change heaters during the building heating period are comprehensively evaluated. Results indicate that indoor temperatures are generally within the thermal comfort range under various initial temperatures and air inlet velocities. Start-stop frequencies of the PCM system increase while total working times decrease with the augment of air velocity. Liquid fractions of PCM decrease as studied time elapses, and several parallel stages occur owing to intermittent operation of active phase change heaters. Parametric analysis reveals that thermal resistance is determined as the most decisive factor, followed by ambient temperature, PCM melting point, and PCM thermal conductivity. The liquid fraction of PCMs declines to merely 0.074 when thermal resistance increases to 0.4 (m2 oC)/W. In conclusion, the studied results highlight the correlation between building thermal performance and specific heat transfer characteristics of PCM, with substantial benefits to the development of latent heat thermal energy storage available for building energy conservation.

Citation: Zhang, Z., Zhang, N., Yuan, Y., Phelan, P. E., &  Attia, S. (2023). Thermal performance analysis of an existing building heating based on a novel active phase change heater. Energy and Buildings, 278, 112646.

📣 Read and share the 📄 article. The paper is available in Open Access format: https://lnkd.in/eayqhdAE The article was published by Zhaoli Zhang, @Nan Zhang, Yanping Yuan, and Patrick Phelan, and Shady Attia.

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