The present study aims to investigate the effect of the pulsed fluid flow on the thermal performance of a latent heat storage unit (LHSU). The storage unit consists of a shell-and-tube in which phase change material (PCM) occupied the shell space and the heat transfer fluid (HTF) flows in the inner tube. The present study is motivated by the need to intensify heat transfer and accelerate melting process in LHSU. A mathematical model based on the conservation equations of energy in both HTF and PCM has been developed. The finite volume approach was used for the discretization of equations. The developed model has been validated by comparing the obtained numerical results with experimental, analytical, and numerical data found in literature. The effects of the pulsation frequency and amplitude, the Reynolds and Stefan numbers on the thermal performance and behavior of the LHSU were investigated. The parametric study showed that the pulsating parameters (frequency and amplitude) affect the thermal performance of the LHSU. The results reveal reduction in the melting time for low pulsating frequency (less than 0.052) and high pulsating amplitude. For pulsating amplitude of 6 and pulsating frequency of 0.01, a reduction up to 13% (at Reynolds number of 500 and Stefan number of 0.16) was obtained. The results also showed that the Reynolds and Stefan numbers strongly affect the heat transfer rate, and the low melting time is obtained for high Reynolds and Stefan numbers.

The proposed work presents a numerical investigation of the melting of a phase change material (PCM: Paraffin wax P116) dispersed with nanoparticles (Al2O3) in a latent heat storage unit (LHSU). The latter is composed of a number of vertical and identical slabs of nano-enhanced phase change material (NEPCM) separated by rectangular channels through which passes heat transfer fluid (HTF: water). A mathematical model based on the conservation equations of mass, momentum and energy has been developed. The resulting equations are discretized using the finite volume approach. The numerical model has been validated by experimental and numerical results published in literature. Numerical investigations have been conducted to evaluate the effects of the volumetric fraction of nanoparticles, HTF mass flow rate and inlet temperature on the latent heat storage unit’s thermal behaviour and performance. Modelling results show that the volumetric fraction, HTF mass flow rate and inlet temperature need to be designed to achieve a significant improvement in thermal performance.

Considering the growing need for developing ecological materials, this study investigates the acoustic, mechanical, and thermal properties of wood composites reinforced with beech or oak wood fibres. Scanning electron microscopy (SEM) revealed a complex network of interconnected pores within the composite materials, with varying pore sizes contributing to the material’s overall properties. Acoustic characterization was conducted using a two-microphone impedance tube. The results revealed that the fibre size significantly impacts the sound absorption coefficient, demonstrating that the highest sound absorption coefficient of 0.96 corresponds to the composites reinforced with oak wood fibres with a size of 2 mm in the low-frequency range of 1000–2500 Hz. Mechanical testing revealed a significant reduction in compressive strength as fibre size increased from 0.4 mm to 2 mm, correlating with the observed changes in sound absorption and thermal properties. Thermal analysis indicated thermal conductivity (λ) values ranging from 0.14 to 0.2 W/m·K, with a notable increase in conductivity as fibre size decreased. It was shown that composites reinforced with beech or oak wood fibres with a size of 2 mm are recommendable for insulation materials due to the lowest thermal conductivity of 0.14 W/(m·K). Oak wood composites with a fibre size of 0.4 mm recorded the highest heat capacity, which is 54.4% higher than the one corresponding to the composites reinforced with the largest fibres. The results regarding heat diffusion rates are also reported. The findings about the effects of fibre size and pores on thermal, acoustic and mechanical properties provide valuable insights for designing sustainable materials, offering potential applications in industries where balanced performance across multiple properties is required.

This study focuses on the development, characterization, and numerical simulation of novel composite materials based on natural vegetable fibers for applications in civil engineering. Three different bio-based composites were formulated using Alfa plant fibers, wood waste, and an equal mixture of both (50% Alfa, 50% wood), with polyvinyl acetate (PVAc), a non-polluting polymer matrix, as the binder. The performance of these composites is strongly influenced by the fiber morphology, structural characteristics, and the nature of the matrix. Thus, understanding and optimizing these parameters is crucial for tailoring materials to meet specific design requirements. The experimental approach began with the morphological and structural characterization of the raw and treated fibers, followed by the evaluation of the thermal a properties of the resulting composites. Furthermore, thermal conductivity simulations were performed using COMSOL Multiphysics to validate the experimental results and gain deeper insights into heat transfer behavior within the composites. A comparative analysis with conventional synthetic insulation materials revealed that the developed bio-composites offer competitive thermal performance while being more environmentally sustainable. These findings highlight the potential of Alfa and wood waste fibers as effective, eco-friendly alternatives for thermal insulation in building applications.

This paper numerically investigates the effect of the location of a horizontal fin on the melting of a phase change material (PCM) inside a rectangular enclosure heated by multiple discrete pulsed protruding heat sources. The fin and the phase change material filling the enclosure store the thermal energy extracted from the heat sources, in sensible and latent forms. The heat sources are assumed to simulate electronic components undergoing a superheating technical issue. By extracting heat from the electronics, the PCM plays the role of a heat sink. To analyze the thermal behavior and predict the cooling performance of the proposed cooling system, we derive a nonlinear mathematical model based on mass, momentum and energy conservation laws. Several numerical investigations are conducted to quantify the influence of the fin position on the thermal behavior and the cooling performance of the heat sink. Predictions include the transient maximum temperature occurring inside the heat sources and the liquid volume. A comparison between our numerical results and experimental data selected from the literature shows a good agreement. The main conclusion is that the presence of the fin leads to a slight increase in the melting time.