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The size and shape of solar box cooker is determined by the volume of the vessel, which in turn depends on the number of family members. The primary objective of this study is to overcome the obstacles inhibiting researchers from crafting solar box cookers tailored to their specific research needs, as well as hindrances preventing manufacturers from effectively bringing them to market. This experimental study aims to identify two novel optimal volumetric efficiencies (VE1 and VE2) to minimize cooking time. To achieve this goal, we employed two identical solar box cookers made from the same materials and four vessels. The results obtained clearly show that the absorber temperature reached a maximum value of 124.9 °C and the boiling time was the shortest 02h50 when the first volumetric efficiency VE1 had the least value of 6.2% and the second volumetric efficiency VE2 had the greatest value of 100%. It is concluded that these two volumetric efficiencies could serve as benchmark parameters for future research, providing a standardized reference for developing solar box cookers of varied shapes and sizes under the same climatic conditions.

The primary goal of this paper is to assess the thermal behaviour of Earth-to-Air Heat Exchanger (EAHE) under continuous operation mode during the cooling period in warm climatic conditions. An experimental setup was conducted in Biskra University (Algeria) to test the ability to use EAHE as an alternative solution to conventional air conditioning systems. Besides, a transient numerical approach for the flowing air within the EAHE was developed using energy balance equations, discretised by the implicit finite differences method and solved by Thomas method. Furthermore, the transient temperature profile of the soil around the EAHE was investigated in order to determine the adiabatic radius of the soil as a function of the duration of operation. In this context, a transient semi-analytical model was integrated to the air model to estimate the transient EAHE’s performance deterioration. This deterioration is produced by the thermal saturation of the soil, which is influenced by the heat released from the air inside the pipe. Results showed that continuous operation for a duration of four days has minimal impact on the outlet air temperatures due to the implementation of night purging. Furthermore, the design and thermal efficiency of the EAHE are impacted by factors such as higher air velocity and reduced soil thermal conductivity.

In this research study, the development of a theoretical model to estimate the efficiency of a double pass solar air heater (DPSAH) was the main objective. The mathematical model was compared to experimental results and found to be in agreement, both qualitatively and quantitatively. The model used energy balance equations to determine the outlet temperature and could solve the temperature equations of each component of the heater simultaneously. A matrix inversion method was used for this purpose. The study found that increasing the Nusselt number led to an increase in energy efficiency, but also caused a drop in outlet temperature at any solar radiation. The mass flow rate (MFR), with larger flow rates resulting in better efficiencies, had a significant impact on the double pass air heater's efficiency. Thus, increasing of DPSAH’s length increases its thermal performances and reach its maximum values for L=9m. These findings could be beneficial in selecting the most efficient design parameters for DPSAH.

The current study focused on the adaptation of adsorption cooling systems to hot and arid climates. A new combination is proposed to improve the performance of the direct evaporative cooler (DEC). This combined system consists in coupling Ground-Water Heat Exchanger (GWHE) with a DEC of a hybrid cooling tower. A mathematical model has been developed and validated to depict the heat and mass transfer that occurs in the DEC between the air and water, as well as between the ground and water in the geothermal heat exchanger. The key variables taken into consideration are the outdoor air temperature and the mass flow rate and the temperature of water. The effect of the inlet hot air velocity and temperature, and water mass flow rate, on the evaporated water is investigated. The findings indicate that the mathematical model of a DEC coupled to GWHE predicts optimal characteristics, leading to a reduction in the air temperature from 48°C to 32°C at the heat exchanger inlet of the cooling tower. [ABSTRACT FROM AUTHOR]

This paper aims to study an earth-air heat exchanger system proposed to cover the living environment needs and reduce energy consumption and greenhouse gas emissions of an industrial poultry house in southern Algeria. For this purpose, a detailed mathematical model was used to determine the thermal needs of this industrial building. The soil temperature was studied to estimate the appropriate depth for installing the earth-air heat exchanger, followed by a parametric and economic study to determine its dimensions and cost. Finally, compare its performance with the systems currently used in this industrial farm. The study results, which were obtained in extreme working conditions, showed that the earth air heat exchanger could cover 45% and 38% of the heating and cooling demands, respectively. In summer, the proposed heat exchanger was able to reduce the temperature from 47°C to 27.1°C, while in winter, it was able to increase the temperature from 4.8°C to 22.9°C, and its performance was stable compared to the systems currently used, and, it recorded temperatures better under hot outside conditions. Furthermore, its use reduces CO2 emissions to 719 kgCO2/day in heating and 2531 kgCO2/day in cooling, making it a suitable solution for this type of industrial building. [ABSTRACT FROM AUTHOR]

The purpose of this study is to present a technical solution to avoid the malfunction of air coolers and condensers when the ambient temperature exceeds the operating limits of these systems. These critical climatic conditions are obtained especially during scorching temperatures in hot climates. First, this article describes this technical solution called Geothermal Air-Cooler (GAC). Second, to design the GAC components, a simple calculation methodology is presented and validated. A real dry cooling tower, available in the literature with its technical characteristics, was considered as a case study applied to the region of Biskra (Algeria). The GAC principle is to use an air mixer to couple a finned tubes heat exchanger (air condenser or dry cooling tower) with an Earth-Air Heat Exchanger, EAHE. The proposed calculation methodology uses an original model to estimate the soil radius surrounding the pipes, required to the EAHE design. Thermal design of the EAHE is validated using experimental data obtained in a previous research by the authors’ team and good agreements were found (average relative error, ±0.99%). Results relating to the case study showed that the GAC can improve the operating limits of the conventional air conditioning systems to 57°C. Besides, for 0.75, 1.75 and 3.00 kg/s of fresh air mass flow rates, the GAC can increase the operating limit temperature of solar adsorption chiller to 42°C, 50°C, and 57°C, respectively. It has been shown that when a large heat transfer area of finned tubes is required, several EAHEs can be used together.EAHE: Earth-air heat exchanger; EWHE: Earth-Water heat exchanger; GAC: Geothermal air-cooler [ABSTRACT FROM AUTHOR]

This paper interests to the applicability of the solar adsorption air refreshment systems in the semiarid region of Biskra (Algeria) and the water cooling system was investigated. We proposed the replacement of the dry cooling tower (DCT) used in the main system with a supplementary water cooling system based on shallow geothermal energy by using earth-water heat exchanger (EWHE). The supplementary EWHE operates just when the ambient temperature exceeds the operating limits of the DCT. Thus, we have modeled and sized the EWHE by FORTRAN programming code. After the code validation, we have designed the appropriate EWHE to the region keeping the same pressure drop and respecting all the functioning conditions of an experimental SACM found in the literature. Results are very significant and showed that the geothermal solution can effectively replace the DCT and presents an important reduced cost compared with other solutions. [ABSTRACT FROM AUTHOR]

This study aims to valorise industrial waste of Expanded Polystyrene Packaging waste (EPS) and used tire waste, in the production of a new composite material. The new composite material RTPC (Rubber Tire Polystyrene Composite) is a mixture of rubber particles from used tires, as reinforcement, and a matrix obtained by recycling EPS with gasoline. In this study, several matrix/reinforcement weight proportions (25%, 30% and 35%) and several reinforcement particle sizes (2-3, 3-4 and 4-5 mm) were considered. Physical, mechanical and thermal characterization were carried out in order to determine the density, the flexural modulus, the maximum stress and the thermal conductivity of the composite material. According to the obtained results, the RTPC material obtained is considered as a light material with a density between 500 and 600 kg/m³. The thermal characterization tests of the RTPC material also showed that the RTPC is an insulating material with thermal conductivity between 0.22 and 0.23 W/m.K. On the other hand, the three-point bending tests showed that the RTPC material has poor bending properties. The RTPC material can be used in the field of building construction as a good thermal insulator. The RTPC material can be used in other applications as a structural component in sandwich structures if its mechanical properties will improve. [ABSTRACT FROM AUTHOR]

• Experimental setup of an earth air heat exchanger was built in biskra (Algeria). • Numerical model is developed to study the effect of continuous operation mode. • Derating factor is used to evaluate the main parameters in the design of EAHE system. • Continuous operation mode has no remarkable effect during 95 h of operation. The Earth Air Heat Exchanger (EAHE) is a promising passive technique that utilises shallow geothermal energy to improve the thermal comfort in buildings. EAHE has the potential to minimize the amount of electrical energy used by traditional air conditioning systems. The aim of this research is to examine the thermal performance of the EAHE under continuous operation. A transient numerical model was developed using the implicit finite difference method. Afterwards, the thermal performance was evaluated by using the means of derating factor. In addition, an experimental setup is realised in Biskra University (Algeria) to take measurements during cooling period. According to numerical calculations, the high thermal performance of EAHE is dependant on high thermal conductivity of soil and low air velocity. The values of the derating factor in the studied cases ranged from 0% to 35% that can mislead the design of the EAHE if ignored. The experimental findings revealed that for 3.5 m/s of air velocity, the maximum air temperature drop can reach up 19 °C. It is noticed that the initial 33 m of the pipe can provide 91% of the whole reduction in air temperature. In extreme real cases, the maximum air temperature increasing does not exceed 0.85 °C during all 95 h. Consequently, ambient temperature decreases during night operation and then cools the heated subsoil and assists the soil to recover its cooling capacity. [ABSTRACT FROM AUTHOR]