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Refrigeration plays a significant role across various aspects of human life and consumes substantial amounts of electrical energy. The rapid advancement of green cooling technology presents numerous solar-powered refrigeration systems as viable alternatives to traditional refrigeration equipment. Exergy analysis is a key in identifying actual thermodynamic losses and improving the environmental and economic efficiency of refrigeration systems. In this study exergy analyze has been conducted for a solar-powered vapor compression refrigeration (SP-VCR) system in the region of Ghardaïa (Southern Algeria) utilizing R1234ze(E) fluid as an eco-friendly substitute for R134a refrigerant. A MATLAB-based numerical model was developed to evaluate losses in different system components and the exergy efficiency of the SP-VCR system. Furthermore, a parametric study was carried-out to analyze the impact of various operating conditions on the system's exergy destruction and efficiency. The obtained results revealed that, for both refrigerants, the compressor exhibited the highest exergy destruction, followed by the condenser, expansion valve, and evaporator. However, the system using R1234ze(E) demonstrated lower irreversibility compared to that using R134a refrigerant. The improvements made with R1234ze are 71.95% for the compressor, 39.13% for the condenser, 15.38% for the expansion valve, 5% for the evaporator, and 54.76% for the overall system, which confirm the potential of R1234ze(E) as a promising alternative to R134a for cooling applications. [ABSTRACT FROM AUTHOR]

As buildings evolve to meet the challenges of energy efficiency and indoor comfort, phase change materials (PCM) emerge as a promising solution due to their ability to store and release latent heat. This paper explores the transformative impact of incorporating PCM on the hygrothermal dynamics of multi-zone constructions. The study focuses on analyzing heat transfer, particularly through thermal conduction, in a wall containing PCM. A novel approach was proposed, wherein the studied system (sensitive balance) interacts directly with a latent balance to realistically define the behavior of specific humidity and mass flow rates. In addition, a numerical model implemented in MATLAB software has been developed to investigate the effect of integrating PCM on the hygrothermal balances inside the building. The obtained results indicate a consistent response in internal temperatures, specific humidity, and mass flow rates, with temperature differences ranging from 5°C to 13°C and a maximum phase shift of 13 h. In addition, the findings provided valuable insights into optimizing the design and performance of multi-zone constructions, offering a sustainable pathway for enhancing building resilience and occupant well-being. [ABSTRACT FROM AUTHOR]

Natural bio-based insulation materials have been the most interesting products for good performance and low carbon emissions, becoming widely recognized for their sustainability in the context of climate change and the environmental impact of the building industry. The main objective of this study is to characterize a new bio-sourced insulation material composed of fibers and an adhesive based on cornstarch. This innovative material is developed from waste of the marine plant called Posidonia oceanica (PO), abundantly found along the Algerian coastline. The research aims to valorize this PO waste by using it as raw material to create this novel material. Four samples with different volumetric adhesive fractions (15%, 20%, 25%, and 30%) were prepared and tested. The collected fractions underwent a series of characterizations to evaluate their properties. The key characteristics studied include density, thermal conductivity, and specific heat. The results obtained for the thermal conductivity of the different composites range between 0.052 and 0.067 W.m−1.K−1. In addition, the findings for thermal diffusivity and specific heat are similar to those reported in the scientific literature. However, the capillary absorption of the material is slightly lower, which indicates that the developed bio-sourced material exhibits interesting thermal performance, justifying its suitability for use in building insulation in Algeria. [ABSTRACT FROM AUTHOR]

This study presents a thermodynamic analysis of a solar-driven vapor compression refrigeration (VCR) system designed for use in the region of Ghardaïa (Southern Algeria) which is located in a desert with a semi-arid climate where the demand for cooling is high, and the solar radiation is abundant. Two working fluids are tested and compared, the HFC high GWP going to phased out, R134a and the low GWP, HFO refrigerant recently introduced R1234ze. The performance of the solar VCR system was evaluated using a numerical model developed in MATLAB software, based on thermodynamic properties of R1234ze and R134a refrigerants. The results showed that coefficient of performance (COP) and thermodynamic efficiency of the solar VCR system increased with decreasing ambient temperature due to the increase in the compressor power consumption. The COP during the 21st day of July month is obtained in the range of 4.37-5.77 for R1234ze refrigerant which are close and more than 90% of the maximum COP value, while it is in the range of 2.56-3.17 for R134a fluid. The lowest COP values are found around noon hours during 12:00 AM and 15:00 PM. In addition, the greatest amount of the PV power production for R134a and R1234ze refrigerants occurs in the middle of the day (12:00 PM) as 2.8 and 1.6 kWh, respectively. [ABSTRACT FROM AUTHOR]

Vacuum membrane distillation (VMD) is an attractive method for water desalination due to its high pure water permeability under lower operating temperatures, resulting in less energy consumption, lower heat loss via conduction through the membrane surface, and negligible heat transfer by conduction due to the low pressure on the permeate side. The aim of this study is to establish a comprehensive numerical model that describes the water vapor transfer across a hydrophobic micro-porous membrane in single-stage and multi-stage VMD processes for seawater desalination. The numerical predictions are compared to previous experimental data, and a good correlation is observed. The investigation also conducted a sensitivity analysis of process variables and membrane specifications on VMD performance, as well as an assessment of the impact of temperature and concentration polarization. The obtained results showed that the permeation flux reached 18.42 kg/m²·h at 35 g/L feed concentration, 65°C feed temperature, 50 L/h feed flow rate, and 3 kPa vacuum pressure. Moreover, the findings revealed that feed temperature was the most significant factor, while feed flow rate was the least important in determining permeation flux. Additionally, the results indicated that the structure and porosity of support materials play important roles in determining the performance of VMD process. Finally, results confirmed that temperature polarization had a more significant effect on the reduction of permeate flux than concentration polarization. [ABSTRACT FROM AUTHOR]