Iranica Journal of Energy & Environment
Volume:15 Issue: 4, Autumn 2024

The challenge of particle deposition in microchannels has consistently posed issues in nanofluids, adversely impacting the heat transfer rate. This study investigates the novel approach of employing a magnetic field to prevent deposition and enhance the heat transfer of nanoparticles in microchannels, utilizing Euler-Lagrange method. The analysis involves the coupled solution of momentum and energy equations, incorporating forces such as Brownian motion, thermophoresis, drag, and volumetric force. The findings within the explored parameters indicate that temperature variations affecting particles beyond the thermal boundary layer have a comparatively minor impact compared to those within the boundary layer. This presents an opportunity for optimizing nanoparticle consumption. Additionally, the study reveals that a non-developed flow at the inlet results in lower particle deposition compared to a developed inlet. The results show that an increase in the Reynolds number from 50 to 300 leads to a 1.75% increase in the distance of particles from the wall. The study also delves into the positioning of the current-carrying wire, demonstrating that placing the wire at the microchannel entrance significantly reduces particle deposition. Furthermore, the results indicate that with an increase in electrical current up to 4 amperes, the efficiency of non-deposition reaches 100%.

Herein, a non-boiling two-phase flow containing air and water through a downward flow in a vertical tube with helical corrugations has been investigated. In this simulation, various flow rates for air and water are considered, and three corrugation pitches 1, 1.5, and 2 cm are included. It can be seen in the results that the pressure drop values decrease with an increase in volume fraction. It should be noted that the reduction of pressure drop values with the reduction of volume fraction (VF) is based on the reduction of the water flow rate, which is visible. By comparing the pressure drop values for each corrugation pitch, it can be seen that as the pitch decreases, the pressure drop values increase significantly. The results for Nusselt number show that Nusselt number decreased with an increase in the volume fraction. By reducing the water flow rate, the intensity of the main flow is reduced the intensity of turbulence is also reduced and the heat transfer coefficient is reduced. Ultimately, the cost-benefit ratio has been utilized to show real results for each studied case.

In this article, the concentration of some volatile organic compounds (VOCs) in the hot oil sample of the Pars petrochemical ethylbenzene unit is presented. Pars Petrochemical is one of the largest producers of ethylbenzene in the Middle East. The hot oil impurities that were analyzed were benzene and toluene (BT). The hot oil sample was taken in May 2023 at a special sampling station on the site. The presence of BT is related to its intensity in the hot oil sample. The Multiple Headspace Extraction (MHE) method was used for the extraction and quantitative analysis of BT followed by gas chromatography (GC) analysis. A GC with flame ionization detector (FID) instrument was used for the analysis of BT. This method offers advantages for the analysis of volatile pollutants because it eliminates the use of organic solvents and various sample purification steps that often lead to erroneous results. The MHE method is independent of standard concentration and could be used in a wide range of BT in Hot Oil without calibration for different ranges. Also, linearity, detection limits, and accuracy were looked into as part of the validation process. The limit of detection (LOD) and limit of quantification (LOQ), respectively, were between 0.05 - 0.56, and 0.17 - 1.9 mg/kg. Less than 13.95 percent (n= 15) was the relative standard deviation statistically. A quick and easy method for detecting BT in hot oil samples was used for the first time. This work will be a step forward for the detection of other aromatic and cyclic hydrocarbons in hot oil samples.

Considering that the heat required for the Waste heat recovery (WHR) cycle of the engine is provided from two parts of the exhaust gas and the cooling system, the mutual influence of the WHR cycle on the engine performance is undeniable. Therefore, in this numerical study, an attempt has been made to thermodynamically evaluate the effect of the implementation of the WHR cycle on the engine efficiency. For this purpose, the 16 cylinder MTU 4000 R43L heavy diesel engine was simulated and a comparison was made between numerical and experimental results. Finally, the SRC heat recovery cycle was designed and applied in the simulated model according to the desired limits and the temperature range of the engine operation. At low speed with the application of the WHR cycle, the output net power did not drop much, but at the maximum speed and power, a power loss of about 4% is observed. At 1130 rpm, the power did not increase much. At 1600 rpm, the power increase is reduced to about 2.3%. At 1800 rpm, due to the significant increase in exhaust gas temperature, the total power value increased by about 4%.

Insisting on independently providing energy due to fossil fuel availability and Economic-political purposes has imposed financial-environmental risks on countries. Inefficient obsolete infrastructures and technologies have caused devastating losses causing technical vulnerabilities in the energy sector. Ungainful increasing consumption of water resources has superimposed severe environmental degradation, threatening long-term energy planning. Successively, the energy security debate has turned into a challenging necessity for countries. This study developed a classic approach based on Modern Portfolio Theory (MPT) and Capital Allocation Line (CAL) reinforced with aggregated evaluative measures to deal with the financial-environmental complexities of national energy portfolios. Results prove that countries are not even aware of the risky hidden brittleness of their energy portfolio. Futuristic policymaking should be adapted to gradually change the national energy structure from fossil fuel dependency to portfolio thinking to avoid risks and achieve more security.

The purpose of this research is to analyze the energy of a residential building in the city of Tabriz with a cold and dry climate using energy simulation to provide a model to minimize energy consumption. A comparative model of energy consumption analysis in a three-story building unit with dimensions of 181 square meters is presented using 5 layout modes in the wall, floor, ceiling, window and door. The number of 5 designs with different arrangement of rooms and different number of windows were compared in terms of energy conservation in 51 different diagrams and the optimal energy saving design is selected. In the next step, according to the obtained results, the design of the building in the desired site is discussed. At the end, in order to check the amount of energy absorbed in the building, energy diagrams will be obtained for the thermal region of the coldest day of the year. The results show that the most optimal energy consumption of the residential building is related to the design of plan B with the fabric gains value of 41767 Wh. After that, the designed plan A show the most optimal energy consumption in the building with fabric gains value of 41028 Wh in the month of July. The results of this research are useful for energy ‎efficiency of residential buildings and environmental management in future.

The use of microchannel heat sinks is one of the most popular methods for cooling electronic components. In recent years, fractal microchannels have attracted researchers' attention, leading to increased heat transfer and reduced pressure drop compared to parallel microchannels. In this study, two hybrid nanofluids under laminar flow conditions are used for cooling inside microchannels, and simulations are conducted using COMSOL Multiphysics software. Parameters such as pumping power, maximum temperature, and performance evaluation coefficient are investigated for two hybrid nanofluids, Fe3O4-MoS2 and Fe3O4-Al2O3 (mixed 50%-50% and with a volume fraction of 1% for each nanoparticle). The results indicate that the thermal performance of Fe3O4-MoS2 hybrid nanofluid is superior, leading to a 0.5% improvement in the maximum temperature of the heat sink. On the other hand, the use of this hybrid nanofluid increases pumping power by 9% inside the microchannel. Ultimately, the overall system performance is enhanced with the use of both hybrid nanofluids, and the Fe3O4-MoS2 hybrid nanofluid improves the overall system performance by 3.2%, providing better performance and making it more suitable for cooling microchannel heat sinks.

The impact of solar radiation and ambient temperature on solar PV energy yield and its corresponding economic implication was investigated. The electrical load assessment was done by physical inspection through periodic visits to study location. Five different scenarios were investigated for two locations - Ogun and Bayelsa States: Case I considers the PV performance based on the  locations’ historical solar radiation and temperature data, Case II considers  30 % increase in the solar radiation data while the ambient temperature data remains fixed, Case III  focuses on when solar radiation data is decreased by 30 % while the ambient temperature data remains constant, Case IV considers the solar radiation data remains constant while the temperature values are  increased by 30 %, and Case V examined the same solar radiation values with temperature data values being decreased by 30 %. The HOMER pro was used as the implementation tool, Electrical energy yield, Unmet electric load, Net present cost, Levelized cost, and Operating cost for Cases I, II, III, IV, and V in Ota, Ogun State were as follows: 28,659 kWh/y, 4.71kWh/y, $13,537, $0.166, 271.43kWh/y; 37,260 kWh/y, 1.63kWh/y, $12,417, $0.152, 290.43kWh/y; 20,058kWh/y, 3.22kWh/y, $15,663, $0.192, 293.14kWh/y; 28,659kWh/y, 4.71kWh/y, $13,537, $0.166, 271.43kWh/y; and 28,659kWh/y, 4.61kWh/y, $13,437, $0.156, 261.43kWh/y, respectively while similar trend was observed for Otuasega in Bayelsa State. The results of the analysis showed that the optimal performance of the PV module occurred at a higher solar radiation and a lower ambient temperature.

The experimental study of the physicochemical properties of biodegradable composite of sugarcane bagasse-polyester have been investigated. Natural composite materials having biodegradable property which makes them a material with limited lifespan, thereby there is a need to research on these materials beyond their normal scope before their lifespan for solid material applications as current technological concepts advances. In this research, water absorption, specific gravity, and chemical resistance test were conducted on sugarcane bagasse polyester composite of different specimen, using a laboratory beaker filled with distilled water, HCl, NaOH, H2O2, NaOCl and detergent solution, at a particular time observing a suitable ASTM. From the result obtained, specimen with 25 weights % increase in Sugarcane bagasse fibre loading, indicated water absorption value of 1.42 %, which could be acceptable for good resistance to water material. The chemical resistance test, severity of the attack and effect on the appearance and weight of the composites followed the order: 10% HCl > 10% NaOH solutions, the deteriorating effect of the composites showed to be unaffected by neither the amount of filler weight nor the presence of any additive incorporated in the SCB-PES composites.

Providing sustainable energy to achieve favorable economic development has attracted the attention of many governments in recent years. Renewable energies, especially wind energy, have gained considerable media attention recently due to challenges with the use of fossil fuels, including difficulty in accessing and devastating environmental impacts. Extensive efforts have been made in Asia to benefit wind energy regionally, all of which have made Asia a leader in this field. There are a few simulation results in this area, given the importance and need to compile infrastructural strategies and programs that require a thorough understanding of the current state of wind energy usage and determining its potential in different regions. Therefore, this study reports for the first time on surveys conducted on average of 20-year wind speed data collected from 2892 stations in 49 Asian countries and wind speed and power density maps obtained using Geographic Information System (GIS) software and the Boolean method. Besides assessing the problems and issues of energy consumption in countries with high potential wind energy in Asia, in this paper, we try to explore the benefits and requirements of using wind energy in these countries as well as the possibility of maximally using wind energy. According to the results, east and north of Russia, as well as west and southwest Asia are optimal regions for establishing large-scale wind plants; there is no significant potential for the use of wind energy in other regions, especially in the majority of China, ASEAN countries, and their neighboring countries.

The COVID-19 pandemic, which began during early 2020, had been a worldwide problem, resulting in significant fatalities. In China, the pandemic resulted in strict lockdowns, restricted movement, and reduced transportation. This resulted in improvement of air quality in many cities in China. The objective of the study is to compare the nature of air quality pre-COVID period (2018-2019) and during COVID period (2020-2201). The following air quality parameters were investigated, air quality index (AQI), particulate matter (PM2.5 and PM10), sulphur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3), and carbon monoxide (CO). The present investigation results will augment to the current understanding on the air pollution situation during the COVID-19 pandemic in Jiangsu Province in China. The study revealed that air quality in Jiangsu Province improved during the months when COVID-19 positive cases increased. The reduction in air pollutants concentrations started during 2020 and reached a maximum during 2021. Overall the air quality index (AQI) improved by 8.2 % and air pollutant reductions achieved were, PMs (≈ 21%), SO2 (26.2 %), NO2 (13.6 %), O3 (2.4 %) and CO (10.4 %). Cities in Jiangsu Province with high air pollutant concentrations achieved a moderate reduction. The correlation between air pollutants and AQI was positive except for O3. The implications of the study are, reduction of fossil fuel powered vehicles and industrial activity can make notable positive impact on the air quality of the region.

In this paper, a new type of wind collection device that can generate rotating wind for wind power generation has been designed to address the shortcomings of current wind power generation devices. This device can collect wind energy from different directions by changing the direction of the wind. Firstly, the simulation model for this wind collection device had been designed by the software SolidWorks. Secondly, the internal flow field of the model was modeled and simulated using Computational Fluid Dynamics, and the k-ω SST model was selected in Fluent for flow field analysis. The results showed that this device could generate an outlet wind speed of 3.8 m/s at a wind speed of 4 m/s, which verified the wind collection effect of the device. Thirdly, the outlet wind speed was taken as the optimization objective, and orthogonal optimization design was carried out on the guide convex groove in the model, and the optimal design parameters of the guide convex groove were determined. The results showed that when the width of the diversion convex groove is 47.35mm and the height is 10.65mm, the outlet wind speed is the highest, about 3.89m/s. Finally, to verify the analysis results of numerical simulation, the experimental verification of the wind collection device was carried out through physical prototypes. The results indicated that the simulation results are consistent with the physical results The design of this device can provide theoretical support for the subsequent design of a full-direction wind collection device to cope with the complex wind direction conditions.