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Various researchers have developed a model of conventional H2O -LiBr absorption machines, with the aim of predicting their performance. In this paper, the methodology of the adaptation of the characteristic equations is applied; this model is able to represent the cooling capacity of the double effect absorption chiller by means of simple algebraic linear equation. As a result, it is concluded that a good agreement between the theoretical simulation using the thermodynamic model and the results obtained on the literature. The results achieved through the adapted characteristic equations model have a deviation less than 10% for the cooling capacity and the coefficient of performance COP, and less than 15% for the heat capacity comparing to the thermodynamic model results. The developed characteristic equations and their assessment are useful for the simulation and the control purpose.

This work aims to enhance the heat transfer of a small prototype linear Fresnel reflector by using rGO-Co3O4/water hybrid nanofluids at a location in Blida region, in Algeria. Hybrid nanofluids, with varying concentrations (0.05, 0.10, and 0.20 wt%) and temperatures (20–60 °C), are prepared. For 0.2 wt % of rGO-Co3O4 nanofluids, the viscosity and density increased by 70.83%, and 0.47%, respectively, while the specific heat decreased by 0.17% at a temperature of 60 °C over the base fluid data. The receiver pipe energy balance equations are solved using MATLAB software. With the use of 0.2 wt% of hybrid nanofluid, the mean thermal efficiency enhanced by 2.75%–31.95%, the mean exergy efficiency improved by 23.67%–2.27%, and the mean temperature increased by 9.42 °C, while, the receiver pipe temperature decreased by 2.69 °C. In addition, the mean heat transfer coefficient, mean thermal conductivity, Nusselt number, and the performance evaluation criteria were improved by using rGO-Co3O4/water nanofluid at 0.2 wt % by 309.67%, 19.31%, 254.75%, and 240.92%, respectively, while the mean entropy generation and electrical energy consumption decreased by 59.48% and 20.30%, respectively, as the CO2 emission mitigation was 253.94 kg.

This work is focused on the energy recovery potential of olive-oil industry wastes in the region of Tizi Ouzou (north of Algeria). A theoretical modelling and simulation study of a small-scale CHP ...

Non-Newtonian blood flow through an aortic bileaflet mechanical heart valve is investigated numerically using the Casson model for the shear thinning behavior of the blood. The objective of this st...

In order to understand the behavior and to determine the effective operational parameters of a solar-driven ejector air conditioning system at low or medium temperature, a dynamic model depends on the principles of conservation, the momentum mass and energy is developed. For this purpose, the thermodynamic characteristics of the liquid and vapor refrigerant were identified using the Engineering Equation Solver (EES) software. Linear Fresnel solar reflector has been used as a tool to convert solar energy into thermal energy. Water (R718) was used as a refrigerant. The operational conditions for the studied solar-driven ejector air conditioning system are as follows: evaporator temperature “Te =283.15 K”, condenser temperature “Tc =305.15 K”, and generator temperature “Tg = 373.15 K”. The performance of the ejector air conditioning system was compared as a function of the operating parameters of the subsystem. The average value of thermal efficiency of the Fresnel linear concentrator has reached 31.60 %, the drive ratio “ω” is 0.4934, the performance value of the ejector air conditioning subsystem “COPejc” is 60.664 % and the average value of the thermal performance of the machine “STR” has touched 19.17 %. The results obtained through this scientific subject are stimulating and encouraging, where this technique can be used for air conditioning in desert areas in southern Algeria, where fossil energy (petroleum, gas, etc.) is extracted and produced in various types.

In light of the global crises that the world suffers from, the renewable energy exploitation is a viable solution to remedy the various energy crises, knowing that renewable energy is a source of environmental credibility, as it does not cause any pollution or any emissions harmful to the environment. Among the most important renewable energy sources, solar energy is the most important type as it can be exploited thermally by adopting various solar collectors, especially solar concentrators. This paper has been devoted to illustrate the types of solar concentrators, namely point-focus concentrators (Heliostat Field Collectors and Parabolic Dish Collectors) and linear concentrators (Linear Fresnel Reflectors and Parabolic Trough Collectors), in an attempt to clarify its principle and its multiple uses domestically and industrially, especially in areas that are characterized by the abundance of its direct solar radiation. The solar concentrator is a solar thermal energy concentration system, because its use reduces the consumption of fossil fuels harmful to the environment and directly contributes to climate change. Solar thermal concentrators are an effective alternative to fossil generators for thermal energy, as they have many important uses such as the solar electricity production of solar electricity in power plants, industrial and domestic water heating, and have many other industrial uses.

In this study industrial grade Multi-walled carbon nanotubes (MWCNTs) nanoparticles dispersed in distilled water (DW) are investigated to evaluate its impact on the thermal behavior of linear Fresnel solar reflector technology. The stability and thermophysical properties of the MWCNTs/DW nanofluids are obtained experimentally. Stable nanofluids that showed higher thermal conductivity compared to DW were obtained. Thermal conductivity (TC) of the nanofluids increased by 3%, 6% and 7% for the volume fractions of 0.05%, 0.1% and 0.3% at 25 °C, respectively. TC also increased with the increase in temperature (i.e. 11% for 0.3% volume fraction at 70 °C). A one-dimensional model is developed to evaluate the transient behavior of the nanofluid within the linear solar reflector. Matlab code based on the finite difference method is developed to solve the energy balance equations at the different components of the studied solar collector. The numerical model is then validated with experimental results, where a maximum experimental thermal efficiency of 29.205% at 14:00 is achieved. MWCNTs/DW nanofluid with 0.3% volume fraction has the highest thermal efficiency of 33.81% and the highest PEC value as well as the lowest entropy generation.

An experimental and numerical investigation of a small linear Fresnel for water heating application has been carried out in Blida, Algeria. The numerical simulation with a 1D modeling in transient mode was performed by using the finite difference method. The thermal evaluation is based on the energy assessments characterized by the differential equations of pure water with a flow mass rate equal to 0.015 kg s−1 and copper absorber tube temperature. Moreover, the Fluent code has been developed in order to conduct the CFD modeling at the absorber tube of the solar collector. SolTrace software has been used to determine the optical behavior of the linear reflector. The average optical efficiency of the device is about 42.97%, but the average value of the experimental thermal efficiency reached 29.21% for 22/01/2015 and 29.20% for 19/02/2015. The average value of pure water temperature for 22/01/2015 is 67.28 °C, while its value for 19/02/2015 is 70.99 °C. This solar experimental setup will reduce the consumption of liquefied natural gas by 88.9 m3, which will reduce the CO2 emission by 187.93 kg. In addition, its manufacturing cost will be recovered 16 years from the date of use of this heater.

An experimental and numerical study on the solar water heater is carried out in Blida area, Algeria during winter in this work. Numerical results are confirmed by experimental results, where the numerical results are presented in two forms: Numerical solution based on estimated equations of climatic data and numerical solution based on actual values of weather data. Finite difference method was used to analyze and simplify energy balance equations. Results obtained showed a significant convergence between experimental and numerical results, where optical efficiency has passed 42.65 %, while the highest value for thermal efficiency was 29.212 % on February 22, 2015, while its average exergy efficiency for February 19, 2015 is 1.81 %. Experimentally, the maximum value of hot water temperature reached 352 K on February 19, 2015. As for the volume of water heated by the studied collector, it is 0.4 m3/day. The system performance is 19.75%, the equivalent of an electrical capacity of 545.68 kWh. Economically, the LFR reflector cost is 378.87 $, where this cost can be recovered after sixteen years of the first use, as the cost of heat generation is 0.043 $/kWh. Environmentally, the CO2 mitigation is 247.14 kg. Additionally, this reflector will provide the equivalent of 127.47 m3 of Liquefied natural gas.

The concentrating solar systems of linear Fresnel reflectors offer the ability to generate electricity from solar energy. The main objective of this paper is to perform a transient numerical simulation on a linear Fresnel solar reflector directed to produce superheated water steam for the power plants, in order to determine its efficiencies (optical and thermal), where the heat transfer fluid mass flow inside the copper absorber tube is 0.045 kg/s. The dimensions of the studied linear Fresnel solar collector are the same dimension as the modular system Nova-1 of NOVATEC SOLAR Company. The dimension of the studied model is 1D. For this purpose, El-Oued region has been designated as a study field. The twelve recommended average days for months have been selected for the study. This paper was based on a numerical solution using the finite differences method. MATLAB has been used as a software language. The optical efficiency of the LFR solar receiver has reached 53.7% where the thermal efficiency has reached 37.5%, while the pressure drop within the absorber pipe has reached 02 bars. As for superheated steam temperatures variations, it ranged between 233.35 °C and 263.75 °C, knowing that the water steam inlet temperature when entering the absorber tube is equal to 140 °C. As for the overall coefficient of heat loss, its mean value is 5.84 W/m2.°C. The results obtained are very encouraging to invest in this steam power plant, especially in the desert areas, which are rich in solar energy.

Solar energy is one of the most important sources of renewable energies, which is widely used in many fields, such as electricity production through direct production of superheated steam based on Linear Fresnel Reflector. This study aims to show the optical and thermal behavior of linear Fresnel solar reflectors field directed to the electricity production in El-Oued region at Algeria. Four days of different weather data have been selected to track the change in solar field performance. Numerical optical modeling has shown that the optical performance of the solar field has reached 53.60 %, while the thermal study based on the numerical solution of the energy balance equations of the receiver tube proved that the thermal efficiency was 37.3 % and the average thermal loss coefficient was limited between 5.72 and 5.98 W/m²K. As for the superheated steam temperature, the lowest value was recorded in December with a value of 501 K. The results obtained are very compelling and encouraging to invest in this low-cost technology.

The study aims to conduct a numerical investigation of 4E (Energy-Exergy-Economic-Environmental) for an industrial process with linear Fresnel reflector (LFR) coupled with Therminol 66 oil storage tank conducted in the El-Oued region of Algeria. MXene (Ti3C2)/silicone oil nanofluid at various weight concentrations of 0.05%, 0.08%, and 0.1%, flowing in different industrial process centers coupled with LFR has been evaluated. Results show enhanced thermal conductivity of 22%, 40% and 64%, at 0.05, 0.08 and 0.1 wt% of silicone oil nanofluids at a temperature of 150 °C against the base fluid data. Nanofluid shows Newtonian fluid behavior with the examined shear rate. MATLAB code has been developed to solve the heat balance equations. Optical efficiency of LFR enhances to 60.42%, and highest LFR’s efficiencies have been recorded for 0.1 wt% of MXene/silicone oil nanofluid with an average thermal efficiency of 58.07%, exergy efficiency of 12.21%, and performance evaluation criteria of 15.50 %. Using 0.1 wt% of nanofluid in LFR system reduced its cost from 0.95 M$ to 0.92 M$. From energy, and exergy point of view, 3.29 Tons CO2/year, and 0.663 Ton CO2/year were reduced, respectively. Maximum overall annual energy and exergy gain is 47.67 $/year and 9.61 $/year, respectively.

The objective of this paper is the investigation of the annual performance of a solar power plant with linear Fresnel reflectors in the El-Oued region at Algeria. The solar collectors produce water steam that feeds a turbine to produce electricity. The System Advisor Model (sam) tool is used for simulation. The mean net daily electricity production rate from 8:30 am to 5:30 pm is 48 MWe, and the respective annual production is 210,336 MWh/year. The mean daily optical efficiency of the solar field was close to 52%, while the mean thermal efficiency was about 39%. The net daily cycle efficiency is found to be 24%. The net capital cost of the examined system is $393 million, and the developer net present value is $47 million; the investor net present value is $15 million, the entire period of capital recovery is 11 years, and the levelized cost of electricity is 0.0382 $/kWh. The solar power plant leads to the yearly avoidance of 420,672 tons carbon dioxide emissions (operational cost savings of $6.1 million). Based on the obtained results, linear Fresnel reflectors can be used to achieve satisfying, energetic, financial, and environmental performance that can lead to sustainability.

In this paper, the design process steps of a conventional solar parabolic trough with large rim angle are presented. The various parameters which intervene to obtain the suitable parabolic trough form of the concentrator are applied. Through an experimental characterization, the real focal distance and the focal zone size of the designed concentrator have been determined and compared with those calculated theoretically. Then, its concentration ratio is evaluated and the focused solar flux at the focal zone along the absorber tube is calculated using Soltrace code. It should be noted that the wind speed effect was not taken into account in the experimental tests which are conducted under a solar irradiation of 970 W/m2 and a receiver inclination angle of 36° which corresponds to the experimentation site latitude.

In this paper, an experimental and analytical study of various parameters which affected the thermal efficiency as well as total heat loss of solar cylindrical cavity receiver for solar dish is presented. The downward facing receiver having a depth of 20 cm, inner diameter of 10 cm and 19 helically turns of copper tube thermally insulated has been designed. The wind speed effect was not taken into account in the experimental tests which are conducted under a solar irradiation of 957 W/m2 and a receiver inclination angle of 36° which corresponds to the experimentation site latitude. The developed analytical model is based in its structure on the different Nusselt number correlations suggested to evaluate the convective and radiative heat losses through the cylindrical cavity. Then, the model makes it possible to predict the total heat loss in order to determine the receiver thermal efficiency under a given inclination angle. The experimental and analytical thermal efficiency estimations agree reasonably well with a maximum deviation of about 12%.

Going forward towards developing and improving renewable energies in Algeria is one of the main objectives of this study, especially, solar energy that is an exceptional and continuous source of energy. Algerian Sahara has a large area suitable for agriculture, but not connected to the electricity network. Therefore, the construction of solar power plants based on the solar energy concentration has been proposed for the electricity production, which is exploited in the rest of the economic sector of the Algerian state. Through the study conducted under real weather data for the day March 16th, 2018, an optical characterization of a solar power plant of parabolic trough concentrator has been convoyed in El-Oued region, Algeria. The geometrical and the optical characteristics of studied solar collector have been determined, such as the optical efficiency, the local concentration ratio, the cosine effect of the incidence angle, the optical losses at the ends of the receiver tube, the shading effect, the blocking effect, and the coefficient of incidence angle modifier and intercept factor. MATLAB code has been used as a program for numerical programming. Of the most important results obtained, it was found that the optical efficiency has exceeded 77.22 %. As for the local concentration ratio, its maximum value is equal to 116.30 in the lower part of the receiver tube at the peripheral receiver angles “β=91° and 269°", while the minimum values of this important coefficient were recorded at the top of the receiver tube.

In this paper, an experimental and analytical study of the weld nugget development in resistance spot welding process of 304L stainless steel sheets having equal and unequal thickness is presented. Experimentally, the metallographic technique has been used to determine the size and location of different weld nuggets realized under a given welding parameters which varies from no nugget formation to expulsion. Two stainless steel sheet thicknesses (1 mm and 1.5 mm) were investigated. The effects of welding current intensity and time on nugget growth are studied. Moreover, the influence of the electrode applied load in weld nugget displacement has been also investigated. Analytically, a two dimensional thermal model was developed with ability to predict the electrical contact resistance and nugget size during spot welding of equal sheet thicknesses. The maximum nugget thicknesses are reached when the electrical contact resistance becomes maximal, contrary to nugget diameter which is less influenced by the electrical contact resistance. For a given sheet thickness ratio (1/1.5), the nugget displacement induced during spot welding of unequal sheet thicknesses remains not influenced by the variation of the welding parameters.

The main objective of this study is to conduct a controlled thermal investigation of a small Parabolic Trough Concentrator (PTC) under a real climatic conditions for El-Oued region on 16/03/2018, where the water was adopted as a heat transfer fluid. One-dimensional and transient energy balance equations have been analyzed, simplified and then programmed with the Matlab code. What distinguishes this study is the precise tracking of all heat coefficients that would give an accurate representation of the thermal behavior of the studied device. The average optical efficiency of the device has reached 78.55 %, the average value of the thermal efficiency has reached 74.30 %, while the average value of the overall coefficient of the thermal loss is 5.96 W.m-2.°C-1. Water steam has been formed under the effect of practical conditions between 10:20 and 11:50. The results obtained in this study encouraged the research team to start manufacturing this device with the dimensions mentioned in this paper, in order to direct this prototype setup to conduct scientific experiments will be in the field of solar cooling, desalination, water heating and other areas that serve the society welfare and maintain the environment integrity.

This work presents a design and an experimental study of a linear Fresnel reflector solar with trapezoidal cavity. This prototype is used for heating the tap water. The reflector was designed, constructed and tested in mechanical engineering department, University of Blida 1, Algeria. Various combinations of reflecting mirrors were tried to achieve hot temperature at the concentration line. The absorber tube was made of copper; it was painted with black paint and covered by selective suitable surface. The quantity of heat available to the absorber tubes was evaluated and compared with 7, 9 and 11 mirrors. The experimental works on the concentrator were accomplished within two days in the winter of 2015. Water temperature reached a maximum of 74 °C with eleven reflective mirrors. The maximum value of the thermal efficiency is 29.21%. The results obtained are very encouraging for using linear Fresnel concentrator in the solar fields allocated to the domestics and industrial water-heaters.Keywords: Solar energy; design, linear Fresnel reflector; thermal efficiency; solarwater-heater

In this work, a steady three-dimensional RANS numerical simulation has been carried out to investigate the air flow field of a centrifugal compressor used for the turbocharger applications; such a compressor consists of a simple-splitter impeller followed by a vaned diffuser. Particular attention is focused on the diffuser solidity effect on the performance of the turbocharger centrifugal compressor by varying the number of diffuser vanes without changing the number of impeller blades. It is found from the computational fluid dynamics analysis that the diffuser solidity presents a considerable effect on the fluid flow field and turbulence characteristics and then on the performances and operating range of the turbocharger compressor.

This article presents the results of an investigation concerning the application of two configurations of the Dish Stirling system (prototype, mature) in order to use it as stand alone systems under the Algerian climate for three different sites (Algiers, Bechar, and Tamanrasset). Furthermore, this article presents the social and environmental impacts of using this technology. An analysis of the daily performances, monthly performances, and annual performances for the three sites has been presented. In addition, an economic assessment of these systems has been performed. The results show that both Tamanrasset and Bechar are more suitable than the Algiers site for the implementation of the Dish Stirling systems.

The use of solar energy in sunny countries, is an effective outil for compensate the lack in the energy, their benefits are not related only to its economic benefits but especially for the environmental protection, so we must find solutions to the problems of pollution. This work is a theoretical study of a solar flat plate collector; air is used as the heat transfer fluid. In this study, we established in first step calculation of solar radiation in various sites in Algeria (Adrar, El Oued, Bechar, Biskra and Tamanrasset). The second step is the parameters influence study of the sites and climate on the performance of our collector. The results obtained are encouraging for the use of this type in the heating in the winter; also it can be used in different kinds of drying.Keywords: thermal energy; solar collector plane; air; simulation; outlet temperature.

The solar power is a clean and a durable energy; there are several techniques for using them. When necessary to elevated temperatures of heat transfer fluid, this energy must concentration. This paper presents the efficiencies study of a linear solar concentrator of a parabolic trough type. This study was conducted on the device in Guemar area, this region is located in the state of El-Oued, which it is found in the south-east of Algeria. Six typical days were selected to conduct the study in them. The solar collector has been studied optically and thermally. The optical study was using SolTrace. Matlab was used as device of programmation to solve the non-linear system of mathematical equations. The method of finite differences in the implicit case was used as way of solution. The thermal efficiencies of the concentrator are very acceptable, it have exceeded 82 %.Keywords: Solar energy; parabolic trough concentrator; modelisation; optical efficiency, thermal efficiency

This paper is an optical and thermal study of a small model of a parabolic trough solar collector (CTP), which will be used to heat tap water in the winter at Guemar, El-Oued province, Algeria. A mathematical model drawn from the energy balance equation applied to the absorber tube, this model was solved by the finite difference method. A computer program was developed to solve our problem. MATLAB was used as a tool for numerical simulation where it is used to calculate dynamic shifts at the level of the absorbent tube. The results are very honorable and encouraging, where the thermal efficiency of the concentrator had passed 61%, and the fluid temperature had passed 343 K.

The solar energy reaching a given surface is directly dependent on the orientation thereof and the position of the sun. To get maximum energy from the sun, it is necessary a good solar receiver orientation towards the solar radiation where the solar radiation is perpendicular to the solar collector, so the knowledge of the sun's position over time is a very important thing. The intensity calculate of solar radiation received by an inclined surface is the primary objective of this paper. The study is based on the true solar time, the geographic and astronomical data on-site study. Matlab was the simulation tool, where a program was developed to calculate the daily global solar radiation collected by any geographical site depending on the semi-empirical model of PERRIN DE BRICHAMBAUT. The some applications on different places in Algeria, like El-Oued, Biskra, Blida and Oran in the day of March 21, June 21, September 21 and December 21, and the results obtained were confirmed by comparing them with the previously results published by the researchers is of great competence in this field. Keywords: solar energy, global solar radiation, inclined surface, simulation

An investigation for the parametric characterization of the weld nugget development was studied in this work which comprises two principal parts; the first one consists of a metallographic technique study of the nugget during spot welding. One gauge of a 304L stainless steel (1.5 mm) was studied experimentally under various welding parameters like the weld time and welding current. Current range curves, from no weld to expulsion, were generated for this stainless steel at a different weld times. The second part presents an analytical approach developed to predict the weld thickness under the same welding parameters used in the experimental stage. This analytical model is two dimensional and takes into account the thermal properties, electrode geometry and contact resistances. The results obtained through this analytical approach are compared with the metallographic results.

An investigation for the parametric characterization of a solar paraboloid intended to receive a Stirling engine was studied in this work. This one comprises two principal parts; the first one consists of the design of a solar parabolic concentrator having an aperture area of 1.67 m2 with a focal distance of 52.65 cm. Its primary surface was covered by 152 aluminium facets distributed uniformly on eight equal petals. The optical parameters revealed a peak concentration ratio of 40 488, while average concentration ratio is 4920. The real focal distance and the dimension of the sunspot focused at the focal zone are given in experiments after a series of tests. The second part was devoted to the development of an analytical model based on the resolution of the heat equation using the variables separation method. This model adopted is able to predict the distribution of temperature and heat flux at the focal zone. By the application of Soltrace code, it is noted that the predicted results by the analytical model are in good agreement with those obtained by experiments.