Optimizing the regeneration process parameters for forward osmosis to produce clean water at low temperature

One-fifth of the world will face sever water shortage by 2040 as climate change and a growing population pushes up demand. Recently, Qatar water resources are becoming strained and stressed as Qatar only gets seven inches of rain per year. Furthermore, World Resources Institute (WRI) ranked all the countries over the world according to the severity of water crisis and the Middle East was one of the worst regions. Nine countries were considered extremely susceptible and Qatar was ranked as a number 3, after Bahrain and Kuwait. While the country (Qatar) population is growing – as today, 2.5 million residents are forecast to multiply eightfold by 2050. Thermal processes produce more than 90% of desalinated water, where the desalination process is energy intensive, and affecting the environment. The scope of the present work is to develop a process to produce clean water at low operating conditions (temperature Please click Additional Files below to see the full abstract

The effect of injected air bubble size on the thermal performance of a vertical shell and helical coiled tube heat exchanger

In the present study, the effect of injecting air bubble size on the thermal performance of a vertical counter-current shell and coiled tube heat exchanger is experimentally investigated. The experiments were accomplished in a cylindrical shape heat exchanger with a 50 cm height and 15 cm outer diameter. Copper coil with 3.939 m equivalent length and 0.6 cm outer diameter was used to carry the hot fluid (water). Four different cold fluid (shell side) flow rates (Qs = 2; 4; 6 and 8 LPM) under laminar flow conditions (316 ≤ Re ≤ 1223), constant hot (coil side) flow rate fluid rates (Qh = 1 LPM), four different injected air flow rates (Qa = 0:5; 1; 1:5 and 2 LPM), invariant temperature difference (ΔT = 20°C), and constant bubble’s number (1400) were tested. To demonstrate the effect of bubble size, a sparger with orifice diameters of 0.1, 0.8, and 1.5 mm was manufactured and used in the study. The overall heat transfer coefficient (U), NTU, effectiveness, and pressure loss were invested. The experimental results clearly showed that the heat exchanger’s thermal efficiency significantly improved with increasing the shell side flow rate and the injected air flow rate. The maximum improvement in U, NTU, and effectiveness was 153%, 153%, and 68%, respectively. The thermal performance of the heat exchanger was shown to be improved with increasing the bubble size. Although the latter finding agrees with recent CFD published results, more studies need to be confirmed.</p

An Evaluation to the Performance of Evacuated Tube Solar Heaters for Arid and Hot Areas

Solar energy applications could be the best alternative to the conventional fuels for the purposes of domestic, water and space heating and some industries in the sunny, arid, and hot areas. In the present study, the performance of an evacuated tube solar heater for water heating for months of February and March was experimentally investigated. This was performed in a hot and arid area (Nasiriya City, South of Iraq). A solar heater with ten evacuated tube solar collectors with a capacity of 100 liter was used in the experiments. Each evacuated tube had a length of 1.8 m with an outside diameter of 8 cm. It was observed that for the two selected months, water temperature of the solar heater reached a maximum more than 70°C during sunny days with no heat extraction from the tank of the solar heater. Moreover, heat was extracted from the solar collector with four different flowrates 0.5, 0.75, 1, and 1.25 l/min, respectively. The results showed that temperature of the solar heater behaved differently from the static situation. When the heat extraction begun, there was a gradual and noticeable decrease in the water temperature of the heater. The observed decrease was slight with the lowest flowrate (0.25 l/m) and becomes sharp with the highest flowrate (1.25 l/min). However, water temperature of the solar heater remained higher than 40°C for the investigated flowrates except the case of 1.25 l/min. The results showed that evacuated tube solar heater can work efficiently in arid and hot areas in winter and spring seasons when the conditions of solar radiation are suitable.</p

Improvement of Thermal Performance of Coiled Tube Heat Exchanger Utilizing Air Bubble Injection Technique

The heat transfer enhancement in terms of temperature of a vertical helically coiled tube heat exchanger is carried out experimentally. The experiments were achieved in a heat exchanger with a 50 cm height and 15 cm internal diameter under four different cold and three hot water mass flow rates and four different airflow rates. At the same time, the temperature difference was taken invariant (ΔT=20°C). To avoid some uncertainties, the hot side temperature of the heat exchanger was measured via k-Type thermocouples. The results showed that the increase of air injection flow rate improved heat transfer from the hot stream flowing in the coil to the shell's cold stream. An intimate thermal mixing when air injected is clearly observed, which could be responsible for the heat exchanger's thermal enhancement. Finally, the injected air pressure was noticed to be having only a minor effect on thermal performance improvement.</p

Improvement of Thermal Performance of Coiled Tube Heat Exchanger Utilizing Air Bubble Injection Technique

The heat transfer enhancement in terms of temperature of a vertical helically coiled tube heat exchanger is carried out experimentally. The experiments were achieved in a heat exchanger with a 50 cm height and 15 cm internal diameter under four different cold and three hot water mass flow rates and four different airflow rates. At the same time, the temperature difference was taken invariant (ΔT=20°C). To avoid some uncertainties, the hot side temperature of the heat exchanger was measured via k-Type thermocouples. The results showed that the increase of air injection flow rate improved heat transfer from the hot stream flowing in the coil to the shell's cold stream. An intimate thermal mixing when air injected is clearly observed, which could be responsible for the heat exchanger's thermal enhancement. Finally, the injected air pressure was noticed to be having only a minor effect on thermal performance improvement.</p

Biosynthesis of Zinc Oxide Nanoparticles Using <i>Capparis spinosa </i>L. Fruit Extract:Characterization, Biocompatibility, and Antioxidant Activity

Recent years have seen an increase in the acceptance of green chemistry as a viable method for producing nanoparticles. The aim of this work was to investigate the cytotoxicity, antioxidant effect, and hemocompatibility of zinc oxide nanoparticles (ZnO NPs) produced utilizing Capparis spinosa L. (C. spinosa L.) fruit extract as a powerful reducing agent. The reaction rate and ZnO NPs’ shape concerning extract concentration, contact time, pH, and temperature were investigated. The production and characterization of ZnO-NPs were confirmed by ultraviolet spectroscopy (U-V), Dynamic Light Scattering (DLS), zeta potential, Field Emission Scanning Electron Microscope (FESEM), X-ray Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR). The antioxidant activity of ZnO NPs was performed by DPPH assay; hemocompatibility of the erythrocytes and cell-cytotoxic properties were investigated using MTT assay. XRD confirmed the production of highly pure, crystalline ZnO-NPs, while FESEM analyses revealed that these particles were agglomerated and spherical, with an average size of about 37.49 nm. Moreover, UV-Vis absorption was revealed at 366 nm, and tests of ZnO NPs’ ζ potential and DLS revealed values of −44.76 mV and 116.80 nm, respectively. ZnO NPs exhibited good biocompatibility with RBCs in hemolytic activity experiments and did not exhibit any hemolytic reaction at doses ranging from 7.5 to 120 μg/mL. The study concluded that greenly generated ZnO NPs had good antioxidant activity and little cytotoxicity and can thus possibly be developed as a useful therapeutic option.</p

Experimental study on a novel waterless solar collector

This study is an endeavour to introduce a novel approach to enhance the performance of solar collectors. The sun emits sufficient power of solar radiation to meet the demand of energy. Harvesting the renewable solar energy needs advanced technologies and requirements. Solar ponds including salinity gradient solar ponds (SGSPs) are common solar collectors. These ponds are one of the solar energy applications used for many industrial and domestic purposes. However, challenges of the conventional SGSPs such as evaporation, salt diffusion, temperature discrepancy, and layer mixing profoundly and significantly affected their expansion globally. A novel experimental solar collector configuration to overcome the challenges of the conventional solar ponds (solar collectors) is investigated, there is no water body and no salinity gradient to build; it is entirely a collector with no water body. The experimental unit was constructed in an arid area. It is basically a cylindrical tank with a total depth of 1.4 m with three zones or layers to store heat namely, paraffin wax layer (10 cm thickness). The paraffin layer was covered with a layer of coal with a thickness of 30 cm. On the top of coal layer, an air gap with a thickness of 80 cm was left. A clear plastic cover with a thickness of 0.2 cm was utilized to cover the constructed layers and making the air gap. The experimental unit was monitored, and temperature measurements were collected for the period of 17/7/2021-30/9/2021. The results demonstrated that temperature of the paraffin wax layer reached more than 48 °C in a short period and with a small day and night discrepancy (1 °C). Temperature of the paraffin layer remained constant around 43 °C even in night-time during the period of the study. Furthermore, the results showed that temperatures of coal layer and air gap reached the maximum at the daytime of 53 °C and 71 °C respectively with a clear discrepancy between day and night. The results of the present study are encouraging for more investigations in this new direction of solar collectors.</p

The effect of a liquid cover on the thermal performance of a salinity gradient solar pond:An experimental study

Salinity Gradient Solar Ponds (SGSPs) offer the potential to capture and store solar energy for use in a range of domestic and industrial activities in regions with high solar insolation. However, the evaporation of water from these ponds is a significant problem that must be overcome for them to be deployed successfully. Thus, two ponds were constructed in the city of Nasiriya, Iraq. The two ponds were cylindrical with a diameter of 1.4 m and a total depth of 1.4 m. The water body in the two ponds was constructed with layer depths of 0.5, 0.75 and 0.1 m for the lower convective zone (LCZ), non-convective zone (NCZ) and the upper convective zone (UCZ) respectively. One of the two ponds was covered with a thin liquid paraffin layer (0.5 cm) to eliminate evaporation from the surface of the UCZ. The behavior of the standard SGSP and that of the covered pond with evaporation suppressed can be straightforwardly compared. The experimental units were run for six months from 1st of February to 31st of July 2019. It was shown in the first instance that by covering the pond with a thin layer of paraffin, that evaporation could be suppressed. The results showed that for the conventional SGSP, the temperature of the LCZ reached a maximum of ca. 76◦C while in the covered pond the temperature of the LCZ was consistently lower than that in the uncovered pond by approximately 5–6◦C. The results also indicated that the temperature of the UCZ in the covered pond was higher than that in the uncovered pond by about 10◦C in the second half of the study period. However, it was noted that on rainy days the paraffin layer was swept away from the surface; and this could hinder the implementation of thin liquid cover in the large SGSP.</p

Optimization studies of expired mouthwash drugs on the corrosion of aluminum 7475 in 1 M hydrochloric acid:Gravimetrical, electrochemical, morphological and theoretical investigations

The aim of the present work is to study the corrosion inhibition of Al 7475 alloy by an expired mouthwash drug (EMWD) in a 1 M HCl solution. The corrosion rate was optimized by the Doehlert experimental design at various temperatures, concentrations of inhibitor, and rotational velocity. The corrosion behavior was investigated by mass loss, Tafel potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) techniques. SEM, MOMT, XRD, FT-IR spectrum, and drop wettability measurement were used in characterizations of EMWD and surface morphology. Optimum conditions for corrosion control of EMWD on aluminum were 44.12 °C, 141.71 mL/L of EMWD per liter of acid, and 234.89 rpm. Maximum corrosion inhibition efficiency was 84.717% at higher levels of temperature and inhibitor concentration. It is observed that EMWD follows the Langmuir Adsorption Isotherm with negative values of ΔGadso, proposing a stable spontaneous inhibition process. The inhibitor efficiency increased as the inhibitor concentration increased. Moreover, increasing the solution temperature and rotational velocity had an adverse influence on inhibitor efficiency. The results of mass loss were in good agreement with potentiodynamic polarization and EIS. Polarization diagrams revealed that the inhibitor acts as a mixed-type inhibitor. It could be concluded that response surface Doehlert design (RSDD) was adequately applicable in the optimization of corrosion inhibition process variables and that EMWD sufficiently inhibited the corrosion of the aluminum at the studied conditions. Simulation of the EMWD molecules adsorption on the metal surface by quantum chemical theoretical studies was a powerful tool for supporting experimental outcomes.</p

Mass transfer influence on the corrosion inhibition of N80 steel in 1 M H₂SO₄ by green corrosion inhibitor using MATLAB

The corrosion process of steel alloys in acidic environments is typically considered to be governed by charge transfer (activation) control. Nonetheless, in aerated solutions, mass transfer can affect the electrochemical measurements. This study examines the corrosion inhibition of N80 steel in 1 M sulfuric acid using okra leaf extract (OLE), utilizing electrochemical polarization techniques at various concentrations of the inhibitor and different temperatures. The outcomes of electrochemical data of current densities and overpotentials were fitted to a high-order polynomial equation and the Maclaurin series formula. The coefficients of the high-order polynomial equation were evaluated using a non-linear regression method, which is in turn used in the Maclaurin series formula. A series of complex equations were derived, incorporating a factor (β) to account for the impact of mass transfer on the activation-controlled corrosion process. A complex equation set of β-models was processed using MATLAB computer programming. In addition, a β-model was correlated to a mass transfer correction factor (γ) and polarization resistance (Rp). β-values ranged from 0.005 to 0.916 (average 0.198), which indicates the presence of a mass transfer effect in addition to the activation effect (mixed control corrosion mechanism). Conversely, the polarization resistance (Rp) increased with higher inhibitor concentrations and decreased as the temperature rose.</p