Vol 54, No 6 (2018)

The influence of the surface texturing on the efficiency of silicon solar cells is considered. The ability to decrease the thickness of the silicon base at the expense of light scattering in the textured zone is shown as well.

The results of computational studies aimed at determining the coefficient of thermal losses of light-absorbing heat-exchange panels (LAHP) of flat-plate solar water-heating collectors (FPSWHC) through their translucent coatings (TC) are presented. The calculations take into account the effect of free and forced convection on the external surface of the TC, as well as on the convective heat transfer coefficient and the FPSWHC tilt, the atmospheric transparency, and the air humidity on the total heat transfer coefficient from the external surface of the TC to the environment. An example is given to test the proposed approach for practical use to determine the values of \(~\alpha _{{{\text{i}}{{{\text{n}}}_{{{\text{w}} - {{c}_{1}}}}}}}^{\Sigma }\), \(\alpha _{{{\text{ex}}{{{\text{t}}}_{{{{c}_{2}} - {\text{amb}}}}}}}^{\Sigma }\), and their convective and the radiant components, and also the degree of their influence on the value of \({K}_{{{{c}_{{{\text{w}} - {\text{amb}}}}}}}^{~}\).

A 3-D computational fluid dynamics (CFD) investigation on heat transfer and fluid flow of solar air heater duct roughened with transverse rib of non-uniform cross-section of square wave profile has been carried out using ANSYS Academic Research CFD 15.0. For comparison, transverse rib of uniform square and circular cross-section has also been investigated. Relative roughness pitch and relative roughness width of rib roughness have been taken as 10 and 85 respectively. Relative roughness height and Reynolds number were varied from 0.015–0.043 and 3000–15 000, respectively. The present CFD methodology has been validated with the experimental results. The maximum augmentation in Nusselt number over that of smooth duct was 2.2 and the corresponding enhancement of friction factor was 3.4 times.

The issues of water extraction from atmospheric air and the possibility of water extraction for Central Asia are considered.

Numerical modeling of the flow dynamics and heat exchange in the tube receiver of a solar parabolic trough module (PTM) has been performed. The study is based on a dimensionless mathematical model that describes turbulent conduction of heat and momentum. An analysis has been carried out and a turbulence model has been selected. The proposed model describes the features of heat exchange near the wall most accurately. A numerical algorithm and Fortran program have been developed on the basis of the mathematical model. The major geometric, dynamic, and energy parameters of the PTM receiving system have been determined. The results can be useful in designing solar energy systems with parabolic trough concentrators (PTC) of different power and purpose.

This paper presents a systematic approach to empirical model selection for the global solar radiation (GSR) estimation considering the Algerian town of Adrar. The approach is based on various meteorological variables. The accuracy of the selected model is validated using GSR measurements in the considered location (i.e. Adrar) through eight statistical indicators. Long-term six-parameter data measurements are collected. The collected measurements are divided into two subsets; the first subset (from year 2009 to 2013) is used for the modeling purpose, while the second subset (years 2014–2016) is used for the model evaluation purpose. The results show that the statistical performance of the traditional Angström formula for GSR estimation can be significantly improved by including the effect of the maximum and minimum temperatures in the GSR empirical models. In addition, the results show that excluding the cloud cover from the empirical models significantly reduces the statistical performance of these models.

Determination of the technical and economic indicators of solar power plants is examined in the paper. The dynamics of growth of installed capacity of solar power plants is shown. Formulas for calculating the installed capacity cost of solar power plants and the cost of electricity generated by solar power plants are presented. The influence of the service life on the technical and economic parameters of solar power plants is examined.

Fixed speed wind turbines have the advantage of being robust and reliable. They allow a direct connection to the electric. The purpose of the article is to study the aerodynamic behaviour and determine the performance of a fixed speed wind turbine. The work presents an analysis method based on the theory of blade element moments (BEM). The variation of aerodynamic parameters is studied for a wide range of wind speeds. A case study is conducted for the design of a wind turbine adapted to the Adrar site which is located in the Algerian Sahara. The results obtained showed that the wind turbine has maximum efficiency just at the design speed. For speeds higher than the design speed, the efficiency is reduced by the stall effect with decreases in torque due to the fall of the lift force. At wind speeds lower than the design value, the thrust effect increases, which puts the rotor under high mechanical stress and blade rotation decreases with low efficiency.

Materials and technologies applied in the manufacture of equipment and the installation of wind-diesel power generation systems operating in harsh climatic conditions, including those in northern regions, are considered.

This paper presents the results of studying the influence of the biomass moisture content on basic pyrolysis parameters. The studies have established that the yield of biomass pyrolysis products strongly depends on the moisture content of the raw material. The paper gives graphs of the dependence of the mass yield of liquid pyrolysis products on the process temperature and biomass moisture content.

This article proposes a technique for defining the parameters of heat treatment and melting of materials in a solar furnace. The parameters are the flux density distribution in the working zone, the maximum heating temperature and temperature distribution in the working zone, and the specific material melting rate.