Applicability of flashing desalination technique for small scale needs using a novel integrated system coupled with nanofluid-based solar collector

The present study introduces an attempt for the application of flash desalination technique for small scale needs. An integrated system uses a flashing desalination technique coupled with nano-fluid-based solar collector as a heat source has been made to investigate both the effect of different operating modes and that of the variation of functioning parameters and weather conditions on the fresh water production. The flashing unit is performed by similar construction design technique of commercial multi-stage flashing (MSF) plant. The thermal properties of working fluid in the solar collector have been improved by using different concentrated nano-particles. Cu nano-particle is used in the modeling to determine the proper nano-fluid volume fraction that gives higher fresh water productivity. An economic analysis was conducted, since it affects the final cost of produced water, to determine the cost of fresh water production. Although a system may be technically very efficient, it may not be economical. The effect of different feed water and inlet cooling water temperatures on the system performance was studied. The mathematical model is developed to calculate the productivity of the system under different operating conditions. The proposed system gives a reasonable production of fresh water up to 7.7 l/m²/day under the operation conditions. Based on the cost of energy in Egypt, the estimated cost of the generated potable water was 11.68 US$/m³. The efficiency of the system is measured by the gained output ratio (GOR) with day time. The gained output ratio (GOR) of the system reaches 1.058. The current study showed that the solar water heater collecting area is considered a significant factor for reducing the water production cost. Also, the produced water costs decrease with increasing the collecting area of the solar water heater. The volume fractions of nano-particle in solar collector working fluid have a significant impact on increasing the fresh water production and decreasing cost.     

Investigations on the effects of Nano-fluid in ECM of die steel

Formation of spikes in the electrochemically machined workpiece prevents to achieve the better performance of ElectroChemical Machining (ECM). Hence, this research work attempts to investigate the effects of Nano-fluid i.e. Nano Copper particles suspended NaCl electrolyte on the ECM of High carbon high chromium (HCHCr) die steel with a hardness of 63HRc. The influencing parameters are voltage, tool feed rate and electrolyte discharge rate with mixing levels. Seventy-two experiments have been conducted using Nano-fluid and plain NaCl electrolyte based on design of the experiment. The Nano Copper particles in the electrolyte break the gas layer at the inter electrode gap resulting in better MRR and surface roughness due to improved current density across the gap. A maximum MRR of 458.869 mm³/min and a minimum surface roughness of 1.39 μm Ra are obtained using Nano-fluid. The developed ANOVA models prove the significances of influencing factors in obtaining the better performance of ECM.     

Effect of nano-particles on forced convection in sinusoidal-wall channel

In this paper heat transfer and flow field in a wavy channel with nano-fluid is numerically studied. The temperature of input fluid (T_c) is taken less than that of the wavy horizontal walls (T_w). The governing equations are numerically solved in the domain by the control volume approach based on the SIMPLE technique. Copper–water nano-fluid is considered for simulation. A wide spectrum of numerical simulations has been done over a range of Reynolds number, Re_H, 5 ≤ Re_H ≤ 1500, nano-fluid volume fraction, ?, 0 ≤ ? ≤ 20% and the wave amplitude, α, 0 ≤ α ≤ 0.3. The effects of these parameters are investigated on the local and average Nusselt numbers and the skin friction coefficient. Simulations show excellent agreement with the literature. From this study, it is concluded that heat transfer in channels can enhance by addition of nano-particles, and usage of wavy horizontal walls. These can enhance the heat transfer by 50%. The present work can provide helpful guidelines to the manufacturers of the compact heat exchangers.     

Experimental study on pulsating heat pipe with functional thermal fluids

An experimental investigation is conducted to explore the heat-transport capability of pulsating heat pipes (PHP) working with functional thermal fluids (FS-39E microcapsule fluid and Al₂O₃ nano-fluid), by comparing them with pure water. The test tube is a four-turn pulsating heat pipe, made of a copper tube with an external diameter of 2.5 mm, and an inner diameter of 1.3 mm. The results show that the heat-transport capability of PHP can be enhanced by using FS-39E microcapsule fluid and Al₂O₃ nano-fluid as working fluid under specific conditions. When using vertical bottom heat mode, FS-39E microcapsule fluid is the best working fluid and its best concentration is 1 wt%; when using horizontal heat mode, Al₂O₃ nano-fluid is the best working fluid and its best concentration is 0.1 wt%.     

Boiling heat transfer performance and phenomena of Al2O3-water nano-fluids from a plain surface in a pool

Boiling heat transfer characteristics of nano-fluids with nano-particles suspended in water are studied using different volume concentrations of alumina nano-particles. Pool boiling heat transfer coefficients and phenomena of nano-fluids are compared with those of pure water, which are acquired on a smooth horizontal flat surface (roughness of a few tens nano-meters). The experimental results show that these nano-fluids have poor heat transfer performance compared to pure water in natural convection and nucleate boiling. On the other hand, CHF has been enhanced in not only horizontal but also vertical pool boiling. This is related to a change of surface characteristics by the deposition of nano-particles. In addition, comparisons between the heat transfer data and the Rhosenow correlation show that the correlation can potentially predict the performance with an appropriate modified liquid-surface combination factor and changed physical properties of the base liquid.     

Influence of an oxygenated additive on emission of an engine fueled with neat biodiesel

Biodiesel obtained from mustard seed is found to be a promising alternative for petroleum diesel fuel owing to its similarity in physical and chemical properties. In this work, TiO₂ nano-fluid which acts as an oxygen buffer during combustion was added to mustard oil biodiesel (MOBD) to study its effect on emission characteristics of MOBD. TiO₂ nano-fluid can provide high surface energy during the course of combustion and reduces the limitations of neat biodiesel. A four-stroke, multi-cylinder, water-cooled, diesel engine was used in the experiments and was fueled with diesel, neat MOBD and MOBD with TiO₂ nanoparticles at 100 ppm (MOBDT100), 200 ppm (MOBDT200) and 300 ppm (MOBDT300). Experimental results revealed that the TiO₂ nanoparticles had positive effect on the emission characteristics of MOBD as it acted as an oxidation buffer. MOBDT300 showed a reduction in HC, CO and smoke emissions as compared to pure MOBD. In addition, NO_x emissions were also reduced by the catalytic activity of the TiO₂ nanoparticles which reduce the peak combustion temperature. Therefore, TiO₂ nano-fluid had a positive effect on reducing the emissions associated with neat biodiesel.     

Heat transfer enhancement in distribution transformers using TiO2 nanoparticles

A transformer is an electrical device that transfers electrical energy between windings by electromagnetic induction while producing a considerable amount of heat in circuits. The heat produced in windings is removed by an appropriate heat transfer fluid such as liquid dielectrics. The cooling and insulating of a liquid dielectric depend on the properties of the oil filling the transformer. One of the approaches to enhance the thermal and dielectric properties of transformer oil is employing an appropriate nanoparticle in a transformer.In this paper, a three-phase distribution transformer is simulated three-dimensionally in order to study the heat transfer efficiency for pure oil (single phase) and nanofluid (TiO₂ nanoparticles- transformer oil). For both models, the electromagnetic field in solid sections and heat transfer in fluid and solid sections of the transformer are simultaneously investigated. The simulation results show that the presence of TiO₂ nanoparticles in the transformer oil increases the heat transfer coefficient, i.e. adding 1% (vol/vol) of TiO₂ nanoparticles to the transformer oil increases the Nusselt number from 2.17 to 2.49, while the maximum temperature of transformer components decreases from 47.20?°C to 43.05?°C.     

Experimental investigation of silver nano-fluid on heat pipe thermal performance

Nano-fluid is employed as the working medium for a conventional 211 μm wide × 217 μm deep grooved circular heat pipe. The nano-fluid used in this study is an aqueous solution of 35 nm diameter silver nano-particles. The experiment was performed to measure the temperature distribution and to compare the heat pipe thermal resistance using nano-fluid and DI-water. The tested nano-particle concentrations ranged from 1 mg/l to 100 mg/l. The condenser section of the heat pipe was attached to a heat sink that was cooled by water supplied from a constant-temperature bath maintained at 40 °C.At a same charge volume, the measured nano-fluid filled heat pipe temperature distribution demonstrated that the thermal resistance decreased 10–80% compared to DI-water at an input power of 30–60 W. The measured results also show that the thermal resistances of the heat pipe decrease as the silver nano-particle size and concentration increase.