Numerical and Experimental Investigations of Composite Solar Walls Integrating Sensible or Latent Heat Thermal Storage

Abstract

This article studies a composite solar wall with latent storage (TES) designed to heat rooms inside buildings during the cold season. No numerical model of the composite solar wall is currently available in the Dymola/Modelica software library. The first objective of this work is to develop one such model. The article describes the elementary components, along with the equations that allow modeling the heat transfers and storage phenomena governing both the thermal behavior and performance of the solar wall. This model was built by assembling various existing basic elements from the software's "Building" library (e.g., models of heat transfer by convection, radiation and conduction) and then creating new elements, such as the storage element incorporating the phase change material (PCM). To validate this solar wall model, numerical results are compared to experimental data stemming from a small-scale composite solar wall manufactured in our laboratory, and the experimental set-up could be tested under real weather conditions. After verifying the level of confidence in the model, the energy performance of two solar walls, one with a conventional storage wall (sensible heat storage) the other containing a PCM (the same as in the experiment), are compared. The result indicates that the solar wall incorporating a PCM does not in this case release any more energy in the room to be heated. first assessment by E.S. Morse in the 19th century. It was subsequently redesigned as an architectural element by F. Trombe and J. Michel [11], as frequently acknowledged in published papers on: Trombe wall, Trombe-Michel solar wall, or composite solar wall. In current research dedicated to energy and environmental contexts, passive solar wall techniques are more relevant than ever, leading to the development of various passive configurations, namely: (a) the classical Trombe wall: engineering techniques [12], theoretical and experimental investigations of heat transfer [13], comparison of the effects of air flow rate between the one-dimensional and two-dimensional models [14], and the numerical study of thermal performance [15]; (b) the PCM Trombe wall: clay bricks integrating PCM macro-capsules functioning as the storage wall [16], thermal performance of a PCM storage wall in temperate and hot climates [17], a simulation study of building walls using the collector-storage wall integrating PCMs [18], a summary of the investigation and analysis conducted on systems incorporating PCMs as storage elements [19], the heat storage wall of the studied building ventilation using black paraffin wax [20], and experimental investigations of PCM wall thermal performance improved by delta winglet vortex generators [21]; (c) a composite Trombe wall with or without PCM: the numerical study of a composite Trombe wall model both with and without PCM in relying on the Dymola/Modelica software [22], numerical studies of the comparison between two walls using sensible heat (with concrete as the storage wall) by means of TRNSYS software [23], experiment...

Impact of a Composite Trombe Wall Incorporating Phase Change Materials on the Thermal Behavior of an Individual House with Low Energy Consumption

“…The design house was modeled with the thermal simulation software Dymola/Modelica. Moreover, the numerical model of the solar Trombe wall was developed and validated using experimental data from previous studies [38,89].…”

“…This model was validated by comparing the data measured from a small experimental solar wall with the simulated data. The differences between energy balances and temperatures were all within 10% [89]. The weather data are stored in the 'weaBus' component.…”

“…The composite Trombe wall (Figure 3) has been integrated into the south sidewall of the bedroom, which was originally an opaque wall, 1.34 m wide and 2.15 m high (surface area: 2.88 m 2 ). The operating mode and primary characteristics of this solar wall have been described in a previous study [89]. The thermal properties of the defined storage walls, as well as the double glazing and insulating panel, are all given in Table 4.…”

“…The objectives of this study are twofold-producing results on heating energy, and observing temperature comfort inside the house. The previous study pertains to the model, using the Dymola/Modelica program and components from the Buildings [87] and IDEAS [88] libraries, along with the validation of a composite Trombe wall model compared to measurement data [89]. Heat transfer in this model house is considered in 1D terms everywhere except in the ventilated air gap of the solar Trombe wall, where the vertical airflow is taken into account through enthalpic balances and correlations for the calculation of convective exchange coefficients [90].…”

Design Optimization of a Composite Solar Wall Integrating a PCM in a Individual House: Heating Demand and Thermal Comfort Considerations

“…The model and its main characteristics have already been presented in previous work [24] and validated in [44]. The thermal behavior of the house was modeled using the 'MixedAir' component of the 'Modelica Buildings Library' [45], in connecting a solar Trombe wall model developed by our team and presented in [24].…”