Entropy generation analysis of nanofluid flow in a circular tube subjected to constant wall temperature

Due to their improved thermal conductivity, nanofluids have the potential to be used as heat transfer fluids in thermal systems. However adding particles into nanofluids will increase the viscosity of the fluid flow. This demonstrates that there is a trade-off between heat transfer enhancement and viscosity. It might not be ideal to achieve a heat transfer enhancement along with a relatively high pumping power. This study presents an analytical investigation on the entropy generation of a nanofluid flow through a circular tube with a constant wall temperature. Nanofluid thermo-physical properties are obtained from literature or calculated from suitable correlations. The present study focuses on water based alumina and titanium dioxide nanofluids. Outcome of the analysis shows that titanium dioxide nanofluids offer lower total dimensionless entropy generation compared to that of alumina nanofluids. Addition of 4% titanium dioxide nanoparticles reduces the total dimensionless entropy generation by 9.7% as compared to only 6.4% reduction observed when using alumina. It is also noted that dimension configurations of the circular tube play a significant role in determining the entropy generation.     

Emission and performance characteristics of an indirect ignition diesel engine fuelled with waste cooking oil

Biofuel has so far been backed by government policies in the quest for low carbon fuel in the near future and promises to ensure energy security through partially replacing fossil fuels. At present biodiesel is mostly produced by transesterification reaction from oil-seed feedstock and has to conform to ASTM D6751 specifications. Biodiesel sustainability has sparked debate on the pros and cons of biodiesel and the question of food security. The use of waste cooking oil such as palm and coconut oil in diesel engines is more sustainable if they can perform similarly to ordinary diesel fuel (B0). This paper presents the experimental study carried out to evaluate emission and performance characteristics of a multi-cylinder diesel engine operating on waste cooking oil such as 5% palm oil with 95% ordinary diesel fuel (P5) and 5% coconut oil with 95% ordinary diesel fuel (C5). B0 was used for comparison purposes. The results show that there are reductions in brake power of 1.2% and 0.7% for P5 and C5 respectively compared with B0. In addition, reduction of exhaust emissions such as unburned hydrocarbon (HC), smoke, carbon mono-oxide (CO), and nitrogen oxides (NO_x) is offered by the blended fuels.     

Experimental investigation of power management and control of a PV/wind/fuel cell/battery hybrid energy system microgrid

This paper presents an experimental study of a standalone hybrid microgrid system. The latter is dedicated to remote area applications. The system is a compound that utilizes renewable sources that are Wind Generator (WG), Solar Array (SA), Fuel Cell (FC) and Energy Storage System (ESS) using a battery. The power electronic converters play a very important role in the system; they optimize the control and energy management techniques of the various sources. For wind and solar subsystem, the speed and Single Input Fuzzy Logic (SIFL) controllers are used respectively to harvest the maximum power point tracking (MPPT). To maintain a balance of energy in the hybrid system, an energy management strategy based on the battery state of charge (SOC) has been developed and implemented experimentally. The AC output voltage regulation was achieved using a Proportional Integral (PI) controller to supply a resistive load with constant amplitude and frequency. According to the obtained performances, it was concluded that the proposed system is very promising for potential applications in hybrid renewable energy management systems.     

Power-to-liquid hydrogen: Exergy-based evaluation of a large-scale system

Hydrogen as an energy vector is seen as a key for the energy transition. Recently, more than 30 countries have launched their hydrogen strategies and roadmaps. Hydrogen storage and transportation are challenging steps of the hydrogen economy since all available options have significant drawbacks. This paper evaluates a power-to-liquid hydrogen process; the system is “charged” with electricity from renewable sources to produce hydrogen via water electrolysis; the produced hydrogen gas is liquefied and stored at ambient pressure and cryogenic temperature. The purpose of this paper is to report the first evaluation results of a system including a polymer electrolyte membrane electrolyser and a hydrogen liquefier. The evaluation was conducted using exergy-based methods, i.e. exergetic, exergoeconomic and exergoenvironmental analyses. The process of hydrogen liquefaction was simulated with the aid of the Aspen Plus software. The exergetic efficiencies for the liquefaction process and for the electrolyser are 42% and 47%, respectively. While the total exergetic efficiency of the power-to-liquid hydrogen system amounts to 44%. The total exergy destruction for the liquefier amounts to 9.3 MW and for the polymer electrolyser membrane electrolyser amounts to 19.3 MW. The electrolyser followed by the hydrogen compressors were identified as the components with the highest exergy destruction values and investment costs, while the compressors and the recuperators account for the highest exergoenvironmental impact. The sensitivity analysis shows that the specific liquefaction cost of hydrogen strongly varies with the electricity price and the cost of green hydrogen.     

Nitrogen-doped graphene-supported zinc sulfide nanorods as efficient Pt-free for visible-light photocatalytic hydrogen production

Nitrogen-doped graphene-ZnS composite (NG-ZnS) was synthesized by thermal treatment of graphene-ZnS composite (G-ZnS) in NH₃ medium. In the second step, the as-synthesized samples were deposited on indium tin oxide glass (ITO) by electrophoretic deposition for photocatalytic hydrogen evolution reaction. The as-prepared NG-ZnS-modified ITO electrode displayed excellent photocatalytic activity, rapid transient photocurrent response, superior stability and high recyclability compared to the pure ZnS and G-ZnS-modified ITO electrode due to the synergy between the photocatalytic activity of ZnS nanorods and the large surface area and high conductivity of N-graphene.     

Optimization of culture conditions for biohydrogen production from sago wastewater by Enterobacter aerogenes using Response Surface Methodology

Sago wastewater (SWW) causes pollution to the environment due to its high organic content. Annually, about 2.5 million tons of SWW is produced in Malaysia. In this study, the potential of SWW as a substrate for biohydrogen production by Enterobacter aerogenes (E. aerogenes) was evaluated. Response Surface Methodology (RSM) was employed to find the optimum conditions. From preliminary optimization, it was found that the most significant factors were yeast extract, temperature, and inoculum size. According to Face Centered Central Composite Design (FCCCD), the maximum hydrogen concentration and yield were 630.67 μmol/L and 7.42 mmol H₂/mol glucose, respectively, which is obtained from the sample supplemented with 4.8 g/L yeast extract concentration, 5% inoculum, and incubated at the temperature of 31 °C. Cumulative hydrogen production curve fitted by the modified Gompertz equation suggested that H_max, R_max, and λ from this study were 15.10 mL, 2.18 mL/h, and 9.84 h, respectively.     

Curcumin based nanomedicines as efficient nanoplatform for treatment of cancer: New developments in reversing cancer drug resistance,rapid internalization,and improved anticancer efficacy

BackgroundCancer is a group of diseases involving an abnormal growth of cells which tend to proliferate in an uncontrolled fashion and in some cases metastasize to the surrounding tissues (malignancy). Resistance to chemotherapy is typically intrinsic (heterogeneity); however, acquired resistance has also become prevelant due to multiple factors including expression of energy-dependent transporters causing expulsion of internalized drug contents extracellular, insensitivity of tumor cells to drug-induced apoptosis, and induction of drug-detoxifying mechanisms. Curcumin (CUR) has gained widespread recognition due to remarkable anticancer, anti-mutagenic, and anti-metastasizing potentials via downregulation of proliferation of cancer cells and induction of apoptosis. Nevertheless, pharmaceutical significance and therapeutic feasibility of CUR is restricted due to intrinsic physicochemical characteristics including poor aqueous solubility, inadequate biological stability, low bioavailability, and short half-life.Scope and approachOwing to these pharmaceutical limitations of CUR, nanodelivery systems have attained remarkable fascination in the recent years. Therefore, this review was aimed to overview and critically ponders recent developments in improving anticancer viability of CUR.Key findings and conclusionCritical analysis of the literature revealed that nanodelivery systems showed promising efficiency in achieving tumor specific targetability, maximizing internalization of drugs into cancer cells, mitigating tumor metastasis, as well as improving anticancer efficacy of CUR. Moreover, nanocarrier-mediated improved pharmacokinetics, drug accumulation, induced promising cytotoxicity, and enhanced anticancer efficacy by suppressing Egr-1 induction, Mitogen-activated protein kinase (MAPK) pathway, and protein tyrosine kinase (PTK) cascades while mitigating the progression of tumor, have also been discussed.     

Detection of fresh palm oil adulteration with recycled cooking oil using fatty acid composition and FTIR spectral analysis

There is a growing concern over the food safety issue related to increased incidence of cooking oil adulteration with recycled cooking oil (RCO). The objective of this study was to detect fresh palm olein (FPO) adulteration with RCO using fatty acid composition (FAC) and Fourier-transform infrared spectroscopy (FTIR) spectral analyses combined with chemometrics. RCO prepared in the laboratory was mixed with FPO in the proportion ranged from 1% to 50% (v/v) to obtain the adulterated oil samples (AO). FACs for FPO, RCO, and AO were determined using gas chromatography equipped with a flame ionization detector (GC-FID). The compositions of most fatty acids in RCO lied within the normal ranges of Codex standard, except for C8:0, C10:0, C11:0, C15:0, trans C18:1, and polyunsaturated fatty acids (PUFAs), C20:5. PUFAs showed a consistent decreasing trend with increasing magnitude of change with respect to increasing adulteration level and thus might be a good indicator for detecting FPO adulteration with RCO. The evaluation parameters (coefficient of determination, root mean standard error) of the FTIR-partial least square (PLS) model of palm oil adulteration with recycled oil are R² = 0.995 and 3.25, respectively. For FTIR spectral analysis, the distinct variations in spectral regions and aberrations in characteristic bands between FPO and RCO were observed. The optimized PLS calibration model developed from normal spectral of the combined region at 3602–3398, 3016–2642, and 1845–650 cm^?1 overpredict the adulteration level. On the other hand, the discriminant analysis classification model was able to classify the FPO and AO into two distinct groups. Improvement of the principles of combined techniques in authenticating AO from fresh oil is beneficial as a guideline to detect adulteration in cooking oil.     

Actions,emotional reactions and cyberbullying – From the lens of bullies,victims, bully-victims and bystanders among Malaysian young adults

This paper examined the emotional reactions and actions involving cyberbullying, focusing on the cyber bullies, victims, bully-victims and bystanders. Gender analysis was conducted to examine if males and females behave and react differently. Self-administered surveys were used to gather data from a large sample of 1158 young adults, mostly university students in Malaysia (M_age?=?21.0?years; SD?=?2.16). Findings indicate the presence of cyberbullying perpetration after the schooling years, with 8% (N?=?93) bullying, 18.6% (N?=?216) victimization, 15.2% (N?=?174) bullying and victimization, and 53.4% (N?=?675) witnessing a cyberbullying incident in the past one year. Most of the bullies reported to be remorseful; however the majority did nothing after a perpetration. Most of the victims on the other hand, experienced anger, sadness and depression after a victimization with the majority claiming to have defended themselves (75%). The majority of the bully-victims regretted their actions, pitied the victims and felt angry after a cyberbullying perpetration/victimization. Bystanders mostly reported feeling pity for the victim and angry at the bullies, with the majority (61.5%) claiming to have defended the victims. However, 40% of them behaved indifferently out of fear retaliation. Finally, gender analysis revealed females to have significantly experienced more emotions than males whereas more males did nothing after a cyberbullying incident, both as victims and bystanders.