Formulation of a composite of date palm wood-cement

This work reports the results of an experimental study on the incorporation of wood waste date palm reduced in particles for the manufacture of wood – cement composites. These materials are chipper than the conventional insulator material and environmental friendly. Five types of wood – cement composites with various concentrations of the wood particles, ie. 2, 4, 6, 8 and 10% of total volume, were made according to defined protocol and mix design. Their thermal and mechanical properties were measured and compared to other conventional materials. The obtained results show that the thermal conductivity is positively correlated to the content of particles in the mixture. The compressive strength of composites decreases where the content of particles increase. However, taking account of the ASTM C 109 / C109-95 standard, the wood – cement composite contained 10% of wood particles, considered as lightweight concrete, could be used as non-structural material in construction

Experimental Characterization of a Functionally Graded Composite Using Recycled Steel Fiber

Many industries have recently focused on cost-effective materials with good mechanical properties. Steel fiber reinforced cementitious composites have proven their mechanical performance in industrial and structural components. The concept of recycled fiber-reinforced FGM is used as an alternative construction material, which can be one of the proposed cost-effective solutions. To achieve these objectives, an experimental program has been developed. A cementitious composite based on local materials was strengthened in two designs; one strengthened over the entire cross-section and the other strengthened only in the tensile zone. We also substituted a functional gradient material reinforced with recycled fibers considering the following volume fractions: 0, 0.5, 1, and 1.5%. This paper investigates the feasibility of using recycled fibers from industrial waste from steel wool manufacturing as reinforcement. We also characterized their mechanical properties using ultrasonic pulse velocity, compressive strength, flexural tensile strength, and shear strength. The results show that the corrugated recycled fibers are the ideal choice to increase the mechanical performance of the reinforced composite, including the improvement of flexural and shear behaviors. Therefore, the investigated FGC could be a valuable tool to optimize the design process in various structural applications and make the production of mechanically and environmentally economical composites possible. Doi: 10.28991/CEJ-2022-08-05-03 Full Text: PD

Thermal design of air cooled condenser of a solar adsorption refrigerator

The objective of this paper is to study the design of a condenser of a solar adsorption refrigerator which will be tested in the region of Biskra (Algeria). The LMTD (log mean temperature difference) method is used to calculate the size of the condenser applying experimental data obtained from the literature. For this purpose, a calculation code has been developed to determine the total heat transfer area of the heat exchanger. Therefore, we present a comparison between calculated and experimental results obtained from the literature. This comparison allowed the validation of the calculation method by applying the same experimental conditions. The discussion of the results indicates that we cannot use the ambient air in free convection mode as a cooling fluid if its temperature exceeds 30°C. This problem presents the greatest obstacle especially in the Saharan regions, such as in Biskra, where the average ambient air temperature during the summer exceeds 35°C. As a solution, we propose in this article the improvement of the heat transfer by the air-forced convection mode. Thus, it is established that the use of the air fan can extend the operating temperature limits of the condenser above 35°C

Feasibility of solar adsorption air-conditioning in the region of Biskra: Reflection on the government support for electricity bills

In this paper, the feasibility of solar adsorption air conditioning system in the region of Biskra (Algeria) is studied. The main objective is to give a reflection on the current government support for electricity bills. A comparison between three air conditioning systems was made by taking into account economic and environmental constraints: classical mono-split system (A), classical centralized air conditioning chiller (B) and solar adsorption system (C). In the context of the current government support for electricity bills, results show that system A is actually the best choice from the total investment costs, electrical consumption and maintenance point of view. This is observed even with the gain of the electrical consumption obtained in the case of solar adsorption air conditioner (C). From an environmental point of view, the system (C) is more advantageous than the classical systems (A) & (B) especially for its use of the solar energy, its low electrical consumption, low CO2 emissions and low heat rejected to the outside. It can be concluded that the current state policy do not encourage the transition to the use of air conditioning systems operate by renewable energies. Thus, the redirection of the current support for electricity bills to the support of the investment cost of the solar adsorption air conditioner (C) will make it more competitive in the Algerian market. In this case, system (C) can replace, in the long-term, the system (A) used actually

Applicability of solar desiccant cooling systems in Algerian Sahara: Experimental investigation of flat plate collectors

The increasing interest in the development of solar cooling technologies to their various economic and impressive environmental benefits, conducted us to study the feasibility of solar desiccant cooling systems in Algerian Sahara, particularly in the region of Biskra. Thus, we present in this paper, the results of an experimental investigation of solar flat plate collectors (FPCs) to test and estimate their heat regeneration capacity for solid desiccant cooling applications. The applicability of both Pennington and Dunkle cycles taking into account the effects of some parameters such as outdoor humidity and temperature and hot air temperature required to regenerate the desiccant wheel have been studied. From the psychrometric analysis, it was found that the Dunkle cycle is suitable in warm and semiarid climate. In addition, this study has allowed us to show that the temperature achieved by the flat plate solar air heaters in a large band of air flow rate can satisfy the energy needs for the dehumidification in desiccant cooling systems. Hot water produced by the solar water heaters and the stored one are in the operating temperature gap of the system (50-80 °C)

Numerical simulation of convective heat losses in a helical tube of a cylindrical solar receiver

In this paper, natural convection heat losses in a cylindrical solar receiver are investigated numerically. The study is conducted using three helical tube diameters: 12mm, 16mm and 25mm. The diameter of the receiver is 0.3 m with an aspect ratio equal to one and three aperture ratios of 1, 0.75 and 0.5. In each case, the receiver tube inside the cylindrical cavity is modelled by a helical spiral similar to those of real systems. The simulations are performed for three inlet temperatures (of 50, 75 and 100°C) and four receiver tilt angles (of 0, 30, 60 and 900) with a constant mass flow rate of 0.0885 kg/s. The effects of some parameters such as receiver size, boundary conditions, tube diameter, receiver tilt, inlet temperature and opening ratio on convective heat losses and outlet temperature are presented in form of graphs. It has been found that the convective heat losses are reduced by using the adiabatic boundary condition imposed on the half-circumference of the tube. Thus, increasing the helical tube diameter causes an increasing in the convective heat losses. The increasing of the fluid temperature and the opening ratio are found proportional to the increasing of convective heat losses

Effet de l'ajout de polyanioniques et de KCl sur le comportement rhéologique de la suspension de bentonite de Maghnia (Algérie)

Nous étudions l'effet de l'ajout de carboxyméthylcellulose de sodium (CMC) et de chlorure de potassium (KCl) sur le comportement rhéologique d'une suspension de bentonite de Maghnia (Algérie). Des tests rhéologiques ont mis en évidence l'influence du polymère et du KCl sur son comportement en écoulement. Les tests rhéologiques réalisés sur la suspension de bentonite ont révélés un comportement rhéoépaissisant à seuil de type Herschel-Bulkley. Ainsi, Il a été montré que le comportement rhéologique de la solution de CMC domine le comportement des mélanges argile-polymère. L'ajout de KCl provoque une augmentation de la viscosité et de la contrainte seuil expliquée par l'agrégation des particules argileuses due à la compression de la double couche électrique