Solar thermal collector is a device that converts solar radiation into useful thermal energy (heat). This technology has become mature and cost-effective. However, because its input comes from an intermittent source (sun), its production is variable during the day; also it is vulnerable to climatic conditions. To adopt this technology, it is therefore necessary to invest in energy storage means or to use a secondary energy source. In this work, a solar thermal collector has been studied and modeled. The objective of this study consists of: first, analyze the impact of the geometrical form of the absorbing surface on the solar collector's thermal performance. Three geometries are tested, namely flat, triangular, and corrugated. The solar collector is evaluated under a hot climate considering the meteorological data of Er-rachidia city (Morocco). The second part of the present study consists of integrating a latent heat storage system using phase change materials (PCMs) to store part of the heat and exploit it during the night. Integrating PCM in this system is a relevant technique to overcome the problem of intermittency of solar energy. Moreover, according to the findings of this study, a significant improvement of the solar collector thermal performance has been reached. The reduction of the missed thermal energy is from 5.6485 kW h to 4.4566 kW h with the use of PCM and the corrugated surface.

Thermal energy storage systems play a pivotal role in addressing the challenge of aligning energy supply with demand, offering diverse applications in energy management. Latent heat storage (LHS), a promising solution, uses the latent heat of phase change materials (PCMs) to store and release thermal energy efficiently. This study provides a novel and in-depth parametric analysis of a tank integrated with PCM, using advanced computational fluid dynamics (CFD) simulations to explore the system's behavior under varying conditions. The research delves into the evolution of heat transfer fluid (HTF) outlet temperature profiles, liquid fraction dynamics within the capsules, PCM temperature fluctuations, and the energy storage and recovery rates throughout both charging and discharging periods. The findings present new insights into the impact of flowrate variations, highlighting that an increase in flowrate from 0.01 kg/s to 0.03 kg/s results in a significant reduction in stored energy, from 28.692 kWh to 10.598 kWh, and recovered energy, from 25.642 kWh to 7.343 kWh. These results contribute to a better understanding of PCM-based LHS systems and offer valuable guidance for perfecting their performance in real-world applications.

This study numerically investigates the thermo-energetic behaviour of partitioned cavity walls integrating hypothetical phase change material (PCM) arrangements with single and staggered transition temperatures under cyclic thermal excitation representative of building-envelope operating conditions. The investigated configurations included single-PCM cases with transition temperatures of $20 °\mathrm{C}$, $22 °\mathrm{C}$, and $24 °\mathrm{C}$, as well as two staggered multi-PCM arrangements, namely $(20,22,24 °\mathrm{C})$ and $(24,22,20 °\mathrm{C})$. A two-dimensional transient numerical model based on the enthalpy–porosity approach was developed and validated against previously published numerical and experimental studies available in the literature. Several thermo-energetic indicators were introduced, including temperature amplitude reduction, damping factor, heat-flux attenuation, thermal time lag, cumulative transmitted thermal energy, and liquid-fraction evolution. A normalized multi-objective thermo-energetic assessment was additionally performed to identify the most balanced PCM arrangement. The results demonstrated that the $20 °\mathrm{C}$ PCM provided the strongest indoor-side thermal attenuation, reducing the temperature amplitude and heat-flux amplitude at facet $x8$ by $66.34\%$ and $62.20\%$, respectively, while increasing the thermal time lag to approximately $7.41\mathrm{h}$. The liquid-fraction analysis further revealed that latent heat activation remained strongly localized and spatially selective within the partitioned cavity structure. The staggered multi-PCM arrangements generated broader and spatially redistributed latent heat activation patterns, promoting more progressive thermal regulation over time. In particular, the $(20,22,24 °\mathrm{C})$ arrangement produced the highest partial latent activation, with a maximum liquid fraction approaching $0.1596$, corresponding to the highest latent activation ratio observed in the present study (≈15.96%), whereas the reversed arrangement $(24,22,20 °\mathrm{C})$ provided enhanced indoor-side stabilization associated with delayed and spatially redistributed latent heat activation. The combined thermo-energetic assessment further revealed important trade-offs between peak thermal damping, delayed thermal response, and distributed latent heat activation. Overall, the obtained findings demonstrate that both PCM transition temperature and spatial ordering strongly influence the transient thermal behaviour of partitioned cavity walls and should therefore be carefully considered in the design of adaptive PCM-integrated building envelopes.

The continuous increase in the building energy consumption impactes negatively on both energy resources and the environment. In this respect, the use of conventional heating systems affects on both energy consumption and the related co₂ emissions. The present work shows the benefits of using a radiant floor heating system (RFHS) coupled with a solar energy system. In the current study TRNSYS-18 software was used to numerically evaluate the RFHS. To achieve improved efficiency and optimize the performance of this letter, a parametric study was conducted on the solar system characteristics and the heated floor. According to the obtained results the optimal design parameters of the system that lead to a high annual solar fraction (SF=93.72%) are: a parabolic trough collector area of 6 m² with a tilt angle 60°, a mass flow rate of 180 kg/h and 410 kg for the collector and floor heating respectively, and a thickness of 0.07m for the heating floor slab. Furthermore, the total auxiliary energy consumption of the RFHS is approximately 63.42 kWh, versus 1953.41 kWh for a conventional heating system of reference. The economic results of the studied system show that the cost of energy saving is 244.25 €/year, and becomes 257.52 €/year with the production of solar domestic hot water. The payback period is estimated at around 13 years.