An increase in energy demand is leading to the continuous rise in global temperature above pre-industrial levels with the discharges of toxic gases and radiations leading to severe climatical circumstances. Thus, it is mandatory to develop ever-lasting, highly efficient thermal systems to overcome this issue. Scientific works on different nanofluids for enhancing performance in thermal applications have gained attention significantly over the last few years owing to their superior qualities. However, it increases safety and health concerns as they are generally more reactive in solvents. Also, other undesired effects such as corrosion of the equipment, non-biodegradable byproducts occur due to the presence of strong chemicals. Therefore, developing cost-effective, and eco-friendly nanofluids has emerged as an alternate research area that is rapidly growing with a great deal of interest. The current review gives a comprehensive view of the different techniques utilized in the preparation of green nanofluids using several natural extracts. Unique morphology, optical properties, stability, high surface area, less toxicity, and enhanced thermo-physical properties of green nanoparticles makes them a favorable candidate in enhancing the performance of thermal systems. Further, various factors affecting the preparation of green nanofluids are highlighted in addition to the evaluation and enhancement techniques concerning the stability and thermophysical properties. Recent experimental and numerical works on the effect of green nanofluids in thermal systems are critically analyzed and provide an overview from economic and environmental perspectives. The challenges and future developments are highlighted to ensure safer health and environment using nanofluids.
Energy is needed for all community activities, the production of all goods, and the provision of all services. It is extremely important to a country’s economy and wealth. Currently, conventional fossil fuels provide most of the world’s energy. In case of oil and gas fields their energy consumption is totally off-grid, their generation depends upon fossil fuels, the cost of energy consumption of oil and gas fields are too high because operational work of the field is totally depending upon fossil fuels. The development of off-grid renewable energy generation technologies offers the opportunity for tackling these challenges. This study provides a techno-economic feasibility analysis of an off-grid hybrid renewable energy system [HRES] for Pasakhi Satellite Oil & Gas Field, Tando Jam, Hyderabad, Sindh, Pakistan. The proposed hybrid energy system designed for field consists of the different combination of solar Photovoltaics [PVs], wind turbines, batteries, and generator to meet the required energy consumption demand. The renewable hybrid energy system is model and optimized configuration through powerful simulation software Hybrid Optimized Model for Electric Renewable [HOMER] Pro. The optimized configuration of the hybrid system consists of solar PV’s (50 kW), Wind turbines (60 kW), 40 lead-acid batteries (165 Ah and 12V each), 30 kw generator and 100 kW converter. The simulation results show that the proposed system can meet the power requirements of 250 kWh/day primary demand load with 40.21 kW peak load. This system configuration has the Capital Cost $71040, the Net Present Cost [NPC] of $253,159 and Cost of Energy [COE] of 0.215$/kWh. Furthermore, the results of the present study are compared with the literature because of which a cost-effective HRES with a low COE has been established.
The ever-increasing water stress and availability of fresh drinking water are becoming a major challenge in rural and urban communities. The current high-end and large-scale technologies are becoming way more expensive and not friendly to the environment. In this regard, solar still is becoming a prominent and promising future technology due to its environment-friendly nature, less maintenance and operational costs, and simple design. The technological challenge regarding solar still is its low distillate yield. In this study, an attempt has been made to investigate the effect of tin oxide (SnO2) on the absorption surface of solar still towards improvement in sunlight absorption, which would lead to high distillate production rates. Various concentrations of SnO2, i.e., 0.5wt%, 1 wt%, 3 wt%, 5 wt%, 7 wt%, 10 wt%, 15 wt%, and 20 wt%, have been mixed in black and applied on the absorber plate to further optimize the suitable concentration. The experiments have been performed in both indoor (simulated) and outdoor conditions. An increase in surface temperature of absorber plate has been observed with increasing concentration of SnO2 under both the indoor and outdoor conditions, which is due to high solar spectrum absorption properties of SnO2 in the ultraviolet (UV) and near to far-infrared (IR) regions. The highest surface temperature of 101.61°C has been observed for specimens containing 15 wt% SnO2 in black paint under indoor conditions at 1000W/m2 irradiation levels, which is 53.67% higher compared to bare aluminum plate and 16.91% higher compared to only black paint coated aluminum plate. On the other hand, the maximum temperature of 74.96°C has been recorded for the identical specimens containing 15 wt% SnO2 under uncontrolled outdoor conditions. The recorded temperature is 47.96% higher than the bare aluminum plate and 14.88% higher than the black paint-coated aluminum plate. The difference of maximum temperatures under indoor and outdoor conditions is due to uncontrolled outdoor conditions and convective losses.
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