SOLAR ENERGY FOR SEAWATER DESALINATION: REVIEW OF ECONOMICS

Major desalination processes consume a large amount of energy derived from oil and natural gas as heat and electricity, while emitting harmful CO2. Solar desalination has emerged as a promising solar energy-powered technology for producing fresh water. This paper will provide an overview of the economics of solar desalination with an emphasis on the Saudi fact in order to estimate the economic benefits of it in comparison with other desalination systems

Modelling the Wake Flow Behind a Model of Horizontal Axis Wind Turbine using RANS Approach: A Comparative Study

Steady CFD simulations, which is based on Reynolds Average Navier-Stokes (RANS) approach, were conducted for a model of Horizontal Axis Wind Turbine (HAWT) and compared with experimental data in order to assess the accuracy of these models in simulating the wake flow of HAWTs. The models can be categorized into two categories: fully developed models (Standard k-ε model, Realizable k-ε model, and SST k-ω model) and transitional models (K-kl-ω transition model and Transition SST Model). In this paper, ANSYS FLUENT 19.2 was being used to execute the simulations of the model turbine standing on a closed-loop wind tunnel at Norwegian University of Sciences and Technology (NTNU). Experiments were operating on a high turbulence intensity uniform inflow. Velocity, turbulence intensity, and turbulent kinetic energy profiles are illustrated at two downstream cross sections. Furthermore, contours of these parameters are set to investigate the developing of wake flow behind the turbine. It is demonstrated that models reasonably predict the velocity profile at the wake region. Transitional models are more accurate in predicting the power of the turbine. Turbulent kinetic energy and turbulence intensity were underestimated for all models

Theoretical Analysis of Continuous Heat Extraction from Absorber of Solar Still for Improving the Productivity

This paper communicates the theoretical analysis of continuous waste heat extraction from the other side of absorber plate. For theoretical analysis two conditions are determined one is the mass of water in the absorber and another one is mass flow rate of water around the absorber plate. Results indicated that the water temperature is reached maximum at 10 kg of mass and 5 kg/hr mass flow of water and the heat extracted from the absorber is higher at optimum mass flow of 5 kg/hr. Also, the higher temperature difference between the water and the collector cover is found during the off-shine period. The maximum achievable hourly productivity of 0.9 and 0.5 kg is found for the solar still with and without circulation respectively. The yield from present model with continuous heat extraction is increased from 3 to 5.5 kg/m2. As the approached method is more new to the society it may be determined by Agouz- Nagarajan- Sathyamurthy (ANS) model

Study of combustion behaviors for dimethyl ether as an alternative fuel using CFD with detailed chemical kinetics

In the present analysis, the dissemination of dimethyl ether (DME) as an alternative fuel with the charged air inside the HCCI engine chamber until accomplishing the burning procedure have been numerically expected by utilizing CFD with detailed chemical kinetics mechanism. The physical technique of the ignition and pollution arrangement in the engine barrel with DME fuel is examined with a developed hydrocarbon reaction mechanism at various HCCI engine loads. The mechanism is including 81 chemical species and 362 basic chemical reactions. Along these lines, the used CFD/discipline code predicts the admittance of the fuel spray, ignition, and pollutant development of DME as a biodiesel fuel. The split injection technique has been used to inject the dimethyl ether remotely at the engine admission tube. The in-cylinder flow field enhances farther the engine chamber fuel/air distribution. The outcomes showed that the blend of DME fuel with charged air is exact and efficient to accomplish the in-barrel blend homogeneity. It is anticipated that, under every engine working condition the production of the methyl radical is considered as imperative part in dimethyl ether pyrolysis and oxidation. In the meantime, the formaldehyde sub-component is a huge division of the general dimethyl ether (DME) ignition system. Keywords: HCCI engine, Alternative fuels, CFD/chemistry, KIVA-3Vr2 code, Zero-dimensional chemistry code, Dimethyl ether, Biodiese

Floating Photovoltaic Plants as an Effective Option to Reduce Water Evaporation in Water-Stressed Regions and Produce Electricity: A Case Study of Lake Nasser, Egypt

Water resources are considered one of the most critical and indispensable elements to ensure the survival of all living organisms on the planet. Since there is a close relationship between water, energy, and food security, this interdependence presents a major global societal challenge. While Egypt is one of the countries that suffers the most from water poverty, it has Lake Nasser which is considered one of the largest artificial lakes in the world, with an estimated area of about 5250 km2. Hence, this work aims to conserve such water resources while addressing two critical issues related to water and energy. To achieve this goal, this study proposed the use of partial coverage technology on Lake Nasser with floating photovoltaic (FPV) panels. The results of the study showed that the partial coverage of Lake Nasser with FPV panels represents a very effective proposal to preserve the water resources of Egypt, which suffers from water poverty. The savings in water evaporation in Lake Nasser reached 61.71% (9,074,081,000 m3/year) and the annual rate of electricity production was 467.99 TWh/year when 50% of the area of Lake Nasser was covered with FPV panels

High-Resolution and Large-Detection-Range Virtual Antenna Array for Automotive Radar Applications

Collision avoidance and autonomous control of vehicles have become essential needs for providing a high-quality and safe life. This paper introduces a new generic scheme for a virtual antenna array (VAA) and its application in a train collision-avoidance system (TCAS). The proposed TCAS shall have the capability of identifying the range and angle of an object in front of a moving train and provide the required alerts. Thereby, a new virtual array distribution for both the transmitting and the receiving antenna arrays is introduced to get a long-range object detection and high-resolution multi-input multi-output (MIMO) system. This can be accomplished because the VAA radiation pattern is the multiplication of the radiation patterns for both the transmitting and receiving antenna arrays, which is different than each one of them alone. In this work, the VAA is utilized in radar systems in which the radar range depends on the multiplication of the gain of the transmitting and receiving antennas. So, we introduce a new scheme for the general design of VAA-based radars. A prototype for the antenna system was fixed on a of Texas Instruments platform for the cascading radar. One of the main problems of the VAA is the loss of radiated power in undesired directions, which affects the maximum detection range in beamforming systems and degrades the diversity gain in MIMO applications. These issues have been solved by the introduction of the practical implementation of a proposed high-gain, low side lobe level VAA system for automotive radar that is based on the integration of four AWR1243 RF chips operating in a frequency range of 76 GHz to 81 GHz. It was implemented using low-power 45 nm (TI) RFCMOS technology. The measured gain of the realized VAA was 47.2 dBi, which was 1.815 times higher than that of the Texas instrumentation linear frequency modulated continuous wave (TI’ LFMCW) radar, which was 26 dBi. The proposed VAA saved 45% of the required implementation area compared to the TI’ LFMCW antenna array. The VAA system was fabricated and tested in an anechoic chamber, and it was found that the simulated and measured patterns of the proposed VAA were highly matched in terms of half-power beamwidth and side lobe level

Comparative Experimental Study Between Conventional Stepped Solar Still and an Active Stepped Solar Still Incorporated with a Water Circulation System

In the following experimental study modifications were carried out into a stepped solar still, considerably increasing the distilled water productivity. Objective function in present study is the comparison between of an active stepped solar still provided with modifications in a new water cooling circulation depending upon an active mode by means of a PV cell incorporated for a stepped solar still, with a conventional solar still without water circulation. In the study the results of glass cover temperature, basin temperature, and fresh water productivity are collected for both stepped solar stills. Also, the solar radiation rate for a period of June 2018 to November 2018 have been carried out in order to optimize the stepped still performance and its yield as well. It was found that, these additions and modifications highly enhance the evaporation and condensation, so distillate yield was augmented. It was found that, daily distilled water productivity reached about 7.21 l/m2 day for the stepped solar still with water circulation. While corresponding value was 4.45 l/m2 day for the conventional stepped solar still at the same water depth (2) cm at summer times and 6.41 l/m2 day for the stepped solar still with water circulation and 3.5 l/m2 day for the conventional stepped solar still at winter times also at the same water depth. The increase in daily distillate water productivity for a stepped solar still with a PV and water circulation is about 78.24 % higher than that of a conventional stepped solar still. Moreover, the average efficiency of daily freshwater productivity is 42.84 % for a stepped solar still with water circulation, while it was 37 % for a conventional stepped solar still, at the same water depth 2 cm at summer and 40.5 % for a stepped solar still with water circulation and 34 % for a conventional stepped solar still at winter times. The present study held under the climate conditions of Egypt at Faculty of Engineering-Tanta University, Egypt

Experimental investigation on seaweed (sargassum wightii) derived using methanolic extracts

Seaweeds are a primitive type of plant and macro algae, which usually grow in the regions of backwaters, estuaries, and seas, especially in shallow water. They are typically formed, attached, and visualized to the coral reef, rocks, and other substrata wherever available. The seaweeds are collected from the Kanyakumari region and processed for methanol production. The methanol is extracted from the processed seaweed using the Saccharification method. The physicochemical properties of methanol are determined as per ASTM standards. The yield (%) of methanol production depends on the concentration of the substrate and the time duration (24, 48, and 72 h). It is observed that for a substrate concentration of 15%, a maximum yield of methanol is observed. In contrast, when the substrate concentrations lie below 10%, there is a decrease in the methanol yield for all the time durations investigated. Therefore, the maximum yield (51.2%) of methanol is obtained for a substrate concentration of 15% with a time period of about 48 h.The present work concentrated on producing methanol from a high concentration and choice of seaweed (Sargassum wightii)

Thermo-Economic Assessment of Photovoltaic/Thermal Pan-Els-Powered Reverse Osmosis Desalination Unit Combined with Preheating Using Geothermal Energy

Recently, the reverse osmosis (RO) process is widely used in the field of desalinating brackish water and seawater to produce freshwater, but the disadvantage of using this technology is the increase in the rates of electrical energy consumption necessary to manage these units. To reduce the rates of electrical energy consumption in RO desalination plants, geothermal energy and photovoltaic/thermal panels were used as preheating units to heat the feed water before entering RO desalination plants. The proposed system in this study consists of an RO desalination plant with an energy recovery device, photovoltaic/thermal panels, and a geothermal energy extraction unit. To evaluate the system performance, three incorporated models were studied and validated by previous experimental data. The results indicated that incorporating the geothermal energy and photovoltaic/thermal panels with the RO desalination plants has positive effects in terms of increasing productivity and reducing the rates of specific power consumption in RO desalination plants. The average saving in the specific power consumption for utilizing the thermal recovery system of PV panels and geothermal energy as preheating units reached 29.1% and 40.75% for the treatment of seawater and brackish water, respectively. Additionally, the economic feasibility showed the saving in the cost of freshwater produced from the RO desalination plants for incorporating both geothermal energy and photovoltaic panels with a thermal recovery system with reverse osmosis desalination plants of up to 39.6%