Thermophysical Properties of Metal Oxides Nanofluids

Thermophysical properties of TiO2, Al2O3 and SiO2 nanofluids are experimentally investigated and compared with published data. Density has been measured over a range of 25–40°C for nanoparticle volumetric concentration of 0.05–4%. Viscosity experiments were carried out over a wide temperature range, from 25 to 80°C, to determine their applicability in such ranges. Nanofluids with particle volume fraction ranging from 0.02 to 0.03% and 1–4 kg/min were examined for the convective heat transfer and pumping power. The heat transfer coefficient of the nanofluid rises with rising mass flow rate, as well as rising volume concentration of metal oxide nanofluids; however, increasing the volume fraction results in increasing the density and viscosity of nanofluid, leading to a slight increase in friction factor which can be neglected. Addition of surfactants results in part of the increment in viscosity as well. An empirical formula for density is proposed, which also contributes to the novelty of this paper

Exploring the Exhaust Emission and Efficiency of Algal Biodiesel Powered Compression Ignition Engine: Application of Box–Behnken and Desirability Based Multi-Objective Response Surface Methodology

Sustainable Development Goals were established by the United Nations General Assembly to ensure that everyone has access to clean, affordable, and sustainable energy. Third-generation biodiesel derived from algae sources can be a feasible option in tackling climate change caused by fossil fuels as it has no impact on the human food supply chain. In this paper, the combustion and emission characteristics of Azolla Pinnata oil biodiesel-diesel blends are investigated. The multi-objective response surface methodology (MORSM) with Box–Behnken design is employed to decrease the number of trials to conserve finite resources in terms of human labor, time, and cost. MORSM was used in this study to investigate the interaction, model prediction, and optimization of the operating parameters of algae biodiesel-powered diesel engines to obtain the best performance with the least emission. For engine output prediction, a prognostic model is developed. Engine operating parameters are optimized using the desirability technique, with the best efficiency and lowest emission as the criteria. The results show Theil’s uncertainty for the model’s predictive capability (Theil’s U2) to be between 0.0449 and 0.1804. The Nash–Sutcliffe efficiency is validated to be excellent between 0.965 and 0.9988, whilst the mean absolute percentage deviation is less than 4.4%. The optimized engine operating conditions achieved are 81.2% of engine load, 17.5 of compression ratio, and 10% of biodiesel blending ratio. The proposed MORSM-based technique’s dependability and robustness validate the experimental methods

Combination of Co3O4 deposited rGO hybrid nanofluids and longitudinal strip inserts: thermal properties, heat transfer, friction factor, and thermal performance evaluations

The reduced-graphene oxide/cobalt oxide hybrid nanoparticles were prepared based on the in-situ/chemical co-precipitation technique, and they were analyzed by transmission electron microscope, x-ray diffraction, and magnetometer techniques. The hybrid nanofluids were prepared with particle loadings of 0.05%, 0.1%, and 0.2% by dispersing synthesized reduced-graphene oxide/cobalt oxide in distilled water and their physical properties were measured. The thermal performance of the nanofluids was studied, when they flow in the turbulent regime through a circular tube. The thermal performance was also evaluated when straight (longitudinal) strip inserts with aspect ratios of 1, 2, and 4, were used inside the circular. These straight strip inserts by increasing the flow turbulence intensity act as turbulators. Results indicate that with a dilution of 0.2% concentration of hybrid nanoparticles in water, the Nusselt number is enhanced by 25.65%, and it is further enhanced by 110.56% with a straight strip insert of aspect ratio 1. The use of hybrid nanofluids and straight strip inserts leads to a slight penalty in fluid friction. For 0.2% concentration of hybrid nanoparticles in water, the penalty in friction factor is 11%, and it is further increased to 69.8% with 0.2% particle loadings and a straight strip insert of aspect ratio1. Moreover, the thermal performance factor of hybrid nanofluids with and without straight strip inserts presents values higher than 1, which shows the benefit of the prepared hybrid nanofluids in a turbulent flow. A general form of regression equations are developed based on the experimental data.publishe

A HISTORICAL PERSPECTIVE OF TRADE LIBERALISATION DYNAMICS IN BANGLADESH: IMPACTS OF NATURAL CALAMITY RISK, GROSS DOMESTIC PRODUCT, FOREIGN EXCHANGE RESERVE, RELATIVE PRICE AND TARIFF ON IMPORT DEMAND

Purpose: After the trade liberation, Bangladesh has faced the crisis of trade imbalance. Therefore, trade liberation is considered as the driving force behind the crisis. To investigate this historical allegation, this study aims at analysing the factors that determined the post trade liberalisation aggregate import demand function of Bangladesh.   Design/Methodology/Approach: Based on quarterly data from trade liberalisation period to reaching the economic stability period, 1992Q1 - 2007Q4, an autoregressive distributed lag (ARDL) approach to cointegration and an error correction model (ECM) have been utilised to estimate the impacts of natural calamity, gross domestic product, foreign exchange reserve, relative price and tariff on aggregate import demand of Bangladesh. Findings: Empirical results revealed that the natural calamity is identified to be nonresponsive to the nation's aggregate import demand both in the short and long run. This indicates that Bangladesh can meet the natural crisis related demand by herself without influencing its aggregate import demand. Results also revealed that the import volume of Bangladesh is cointegrated with relative import price, actual GDP and real foreign exchange reserve of the country. The import demand of the country can largely be described by its real GDP, while it is found inversely associated with relative price ratio in the long run. The long run association among import demand and tariff rate indicates that trade liberalisation has a significant positive impact on the country's aggregate import demand, as well as real foreign exchange reserve, as explained by the reduction in tariff rate.   Research Implication: Developing countries like Bangladesh and the relevant business stakeholders would have considerable implications of such empirical findings with their trade policies, particularly how they should respond to unpredictable scenarios caused by the factors such as natural calamity, foreign exchange reserve, tariff, etc.   Originality Value: The originality of the study lies in its uniqueness in using the historical data and factors that no studies have so far used in analysing the import demand function of Bangladesh.   Keywords: Natural calamity, import demand, foreign exchange reserve, gross domestic product, tariff, trade liberalisation, Bangladesh.   Cite as: Shikha, H. A., Alam, M. M., Murad, M. W., Said, J., & Ahmed, Z. U. (2023). A historical perspective of trade liberalisation dynamics in Bangladesh: impacts of natural calamity risk, gross domestic product, foreign exchange reserve, relative price and tariff on import demand. Journal of Nusantara Studies, 8(TI), 177-208. http://dx.doi.org/10.24200/jonus.vol8issTIpp177-20

Optimizing density, dynamic viscosity, thermal conductivity and specific heat of a hybrid nanofluid obtained experimentally via ANFIS-based model and modern optimization

In this study, rGO/Co3O4 nanocomposite was synthesized, characterized, and then the thermophysical properties were obtained experimentally, after which the experimental data at varying values of temperature and particle loadings was used for optimization purposes. The study was concerned with different values of the controlling parameters. The in-situ/chemical reduction technique was used to synthesize the rGO/Co3O4 nanocomposite and then characterized with x-ray diffraction, transmission electron microscope, and magnetometry. The system was studied at temperature values ranging at 20, 30, 40, 50, and 60 °C and with particle loadings of 0.05%, 0.1%, and 0.2% wt%. The authors in this article have introduced a novel population-based algorithm that is known as Marine Predators Algorithm to obtain the optimal values of the controlling parameters (i.e., temperature and nanofluid mixture percentage) that minimize two controlled variables (i.e., density and viscosity) as well as maximize the other two controlled variables (thermal conductivity and specific heat). The rGO/Co3O4 nanocomposite nanofluid thermal conductivity and viscosity were investigated experimentally, and a maximum increment of 19.14% and 70.83% with 0.2% particle loadings at 60 °C was obtained. At 0.05%, 0.1%, and 0.2% particle loading wt%, the density increased by 0.115%, 0.23%, and 0.451% at a temperature of 20 °C; simultaneously, density increased by 0.117%%, 0.235%, and 0.469% at 60 °C, respectively as compared to water. At 0.2 wt%, the maximum decreased specific heat was 0.192% and 0.194% at 20 °C and 60 °C. When compared with water, no effect was observed with an increase in temperature/: a similar trend as that of the water was followed. The optimal values were found to be at a temperature of 60 °C and for 0.05% particle loading of the prepared nanofluid. However, among the conducted experiments, the optimizer pointed out that the optimal experiment was the one conducted at a temperature of 60 °C and a nanofluid percentage at 0.05. In conclusion, the proposed methodology of modelling with an artificial intelligence tool such as an adaptive network-based fuzzy inference system technique and then determining the optimal parameters with the marine predators algorithm accomplished the goal of the study with major success.publishe

Thermal conductivity and Thermal properties enhancement of Paraffin/Titanium Oxide based Nano enhanced Phase change materials for Energy storage

The Latent heat storage (LHS) based on phase change materials (PCMs) has a critical part to demonstration in preserving and efficiently utilizing energy, resolving demand-supply mismatches, and boosting the efficiency of energy systems. However, they have a low thermal performance inherent in it because the low thermal conductivity (TC) of PCMs. Paraffin organic PCMs have several advantages such as higher LHS, nontoxic, abundant in nature and inexpensive, whereas TiO2 nanoparticle is type of hydrophilic group having tendency to improve TC. In this research TiO2 in different concentration (0.1, 0.5, 1, and 2 wt percent) with surfactant sodium dodecyl benzene sulphonate (SDBS) added into Paraffin RT44 HC PCM using two step techniques, and the thermophysical properties were broadly discussed. Thermogravimetric analyzer (TGA), Fourier transform infrared spectroscopy (FT-IR) and Thermal property analyzer (TEMPOS) were used for the characterization of prepared composite nano-enhanced phase change materials (NePCM). Additionally, the effect of nanoparticles on TC was investigated. The highest TC was obtained with PW/TiO2-1.0 by an increment of 86.36% as related with base PW. The FTIR spectrum of the composite PW/TiO2 confirmed no interaction between PW and TiO2, resulting in a more chemical stable composite. The addition of TiO2 to PW enhance the degrading temperature 10 C by making it more thermal stable. Grounded on the results it can be concluded that the developed composite is suitable for thermal energy storage (TES), photovoltaic thermal (PVT) systems, and hot water applications

Nano-refrigerants and nano-lubricants in refrigeration : synthesis, mechanisms, applications, and challenges

Addressing global energy security and environmental concerns, the utilization of nano-refrigerants and nano-lubricants has emerged as an innovative path for enhancing heat transfer. This research focuses on enhancing the thermophysical properties, heat transfer efficiency, and tribological characteristics of nanofluids—nanoparticles dispersed in refrigerants or lubricants. These nanofluids have demonstrated significant potential in applications such as cooling, air conditioning systems, and heat transfer equipment including pumps and pipes. A comprehensive understanding of parameters like thermal conductivity, viscosity, pressure drop, pumping power, and energy performance is delivered, with the aim of enhancing the overall efficiency of refrigeration systems, particularly the coefficient of performance (COP). Additionally, the review covers existing research on flow and pool boiling heat transfer, nano-lubricant tribological enhancement, and nano-refrigerant condensation. The study also addresses the challenges associated with the use of nano-refrigerants and nano-lubricants and offers a prospective outlook for their usage. These novel nanofluids are anticipated to emerge as effective solutions for increasing the COP and reducing energy consumption in the industrial sector, thus extending beyond the scope of previous efforts in this field. This review could serve as a valuable resource for a broad audience interested in this novel approach to energy efficiency

State-of-the-art review on electrolytes for sodium-ion batteries: Potential recent progress and technical challenges

Lithium batteries play a prominent role as a critical technology for advancing electric vehicles. However, establishing lithium-based technologies for mass storage encounters critical challenges such as materials availability and cost-efficiency. Hence, strategic approaches should be developed to address the existent challenges. Using sodium as new sustainable chemistry to replace lithium-based technologies tends to exhibit promising solution as the most appealing alternative. While exploring new electrode materials which has attracted significant interest from eminent researchers for sodium-ion batteries, research activities related to electrolyte are less attention paid. This paper reviews the most recent articles on developing and improving the electrolytes for sodium-ion batteries, particularly liquid electrolytes. This is the latest comprehensive discussion related to sodium-ion batteries with different type of electrolytes and a particular focus on the advantages/disadvantages in order to improve efficiency of these novel technologies as well as comprehensive discussion on the application of advanced nanomaterials towards these devices

Experimental investigations on thermal properties of copper (II) oxide nanoparticles enhanced inorganic phase change materials for solar thermal energy storage applications

Due to the current environmental catastrophe and energy crises, the government and industries shift towards sustainable, renewable, and clean energy sources. This circumstance motivates the harvesting of energy from all available sources. Phase change materials (PCM) are latent heat storage (LHS) substances and have been proven one of the potential techniques for thermal energy storage (TES). However, PCMs possess some disadvantages lies lower thermal conductivity, due to that the heat transfer and heat storage capacity are less. In this present work, feasibility and thermal conductivity enhancement of dispersing Copper (II) Oxide (CuO) nanoparticles in six various weight concentrations (0.1%, 0.5%, 1.0%, 2.0%, 3.0%, and 5.0%) into the salt hydrate PCM with Sodium dodecylbenzene sulfonate (SDBS) were analyzed. A two-step method is adopted for dispersing nanoparticles and PCM. The key objective of the research work is to characterize the elemental mapping, chemical stability, thermal stability, and thermal conductivity of developed CuO enhanced salt hydrate PCM. The Fourier transform infrared (FT-IR) spectroscopy shows the CuO nanoparticles integrated well, and no chemical reaction occurs with nanoparticles, and PCM means chemically stable. The thermogravimetric analysis (TGA) reveals that prepared composite salt hydrate PCM are thermally stable up to 474°C. Furthermore, the thermal conductivity was enhanced by 87.39% during the dispersion of 3.0wt%CuO nanoparticles into salt hydrate PCM. Thus, the newly developed nanocomposite PCM is potential material for medium and low-temperature solar TES applications

The influence of forced convective heat transfer on hybrid nanofluid flow in a heat exchanger with elliptical corrugated tubes : numerical analyses and optimization

The capabilities of nanofluids in boosting the heat transfer features of thermal, electrical and power electronic devices have widely been explored. The increasing need of different industries for heat exchangers with high efficiency and small dimensions has been considered by various researchers and is one of the focus topics of the present study. In the present study, forced convective heat transfer of an ethylene glycol/magnesium oxide-multiwalled carbon nanotube (EG/MgO-MWCNT) hybrid nanofluid (HNF) as single-phase flow in a heat exchanger (HE) with elliptical corrugated tubes is investigated. Three-dimensional multiphase governing equations are solved numerically using the control volume approach and a validated numerical model in good agreement with the literature. The range of Reynolds numbers (Re) 50 < Re < 1000 corresponds to laminar flow. Optimization is carried out by evaluation of various parameters to reach an optimal case with the maximum Nusselt number (Nu) and minimum pressure drop. The use of hybrid nanofluid results in a greater output temperature, a higher Nusselt number, and a bigger pressure drop, according to the findings. A similar pattern is obtained by increasing the volume fraction of nanoparticles. The results indicate that the power of the pump is increased when EG/MgO-MWCNT HNFs are employed. Furthermore, the thermal entropy generation reduces, and the frictional entropy generation increases with the volume fraction of nanoparticles and Re number. The results show that frictional and thermal entropy generations intersect by increasing the Re number, indicating that frictional entropy generation can overcome other effective parameters. This study concludes that the EG/MgO-MWCNT HNF with a volume fraction (VF) of 0.4% is proposed as the best-case scenario among all those considered.Taif University Researchers Supporting Granthttps://www.mdpi.com/journal/applsciMechanical and Aeronautical Engineerin