Thermodynamic Analysis of a Flat Plate Solar Collector with Different Hybrid Nanofluids as Working Medium-A Thermal Modelling Approach.

In this study, the performance of hybrid nanofluids in a flat plate solar collector was analysed based on various parameters such as entropy generation, exergy efficiency, heat transfer enhancement, pumping power, and pressure drop. Five different base fluids were used, including water, ethylene glycol, methanol, radiator coolant, and engine oil, to make five types of hybrids nanofluids containing suspended CuO and MWCNT nanoparticles. The nanofluids were evaluated at nanoparticle volume fractions ranging from 1% to 3% and flow rates of 1 to 3.5 L/min. The analytical results revealed that the CuO-MWCNT/water nanofluid performed the best in reducing entropy generation at both volume fractions and volume flow rate when compared to the other nanofluids studied. Although CuO-MWCNT/methanol showed better heat transfer coefficients than CuO-MWCNT/water, it generated more entropy and had lower exergy efficiency. The CuO-MWCNT/water nanofluid not only had higher exergy efficiency and thermal performance but also showed promising results in reducing entropy generation.

Trends and prospects of geothermal energy as an alternative source of power: A comprehensive review.

The world has capitalized on numerous renewable energy resources by developing its energy infrastructure mainly around solar, biomass, and hydro energy. However, geothermal energy has not yet been developed at a significant scale, despite reports from 62 wells showing evidence of geothermal gradients ranging from 20.8 °C/km to 48.7 °C/km in various areas of the world. Recent studies suggest that Bangladesh also has a huge potential for geothermal energy. This review extensively reports on exploiting the range of geothermal temperature in various direct and indirect energy application sectors including but not limited to the agriculture and industrial sector of Bangladesh. Additionally, the authors have analyzed and proposed adaptable measures to harness the abundance of geothermal energy. Furthermore, a comparative and possible solution has been discussed extensively for implementing a geothermal powerplant by analyzing techno-economic costs, policies, and systems of other countries in the world. Further, this review also shows the prospect of geothermal energy for Bangladesh as a case study.

Influence of oxygen content of the certain types of biodiesels on particulate oxidative potential.

Oxidative potential (OP) is related to the organic phase, specifically to its oxygenated organic fraction (OOA). Furthermore, the oxygen content of fuel molecules has significant influence on particulate OP. Thus, this study aimed to explore the actual dependency of the OOA and ROS to the oxygen content of the fuel. In order to reach the goal, different biodiesels blends, with various ranges of oxygen content; have been employed. The compact time of flight aerosol mass spectrometer (c-ToF AMS) enabled better identification of OOA. ROS monitored by using two assays: DTT and BPEA-nit. Despite emitting lower mass, both assays agreed that oxygen content of a biodiesel is directly correlated with its OOA, and highly related to its OP. Hence, the more oxygen included in the considered biodiesels, the higher the OP of PM emissions. This highlights the importance of taking oxygen content into account while assessing emissions from new fuel types, which is relevant from a health effects standpoint.

Particle emissions from microalgae biodiesel combustion and their relative oxidative potential.

Microalgae are considered to be one of the most viable biodiesel feedstocks for the future due to their potential for providing economical, sustainable and cleaner alternatives to petroleum diesel. This study investigated the particle emissions from a commercially cultured microalgae and higher plant biodiesels at different blending ratios. With a high amount of long carbon chain lengths fatty acid methyl esters (C20 to C22), the microalgal biodiesel used had a vastly different average carbon chain length and level of unsaturation to conventional biodiesel, which significantly influenced particle emissions. Smaller blend percentages showed a larger reduction in particle emission than blend percentages of over 20%. This was due to the formation of a significant nucleation mode for the higher blends. In addition measurements of reactive oxygen species (ROS), showed that the oxidative potential of particles emitted from the microalgal biodiesel combustion were lower than that of regular diesel. Biodiesel oxygen content was less effective in suppressing particle emissions for biodiesels containing a high amount of polyunsaturated C20-C22 fatty acid methyl esters and generated significantly increased nucleation mode particle emissions. The observed increase in nucleation mode particle emission is postulated to be caused by very low volatility, high boiling point and high density, viscosity and surface tension of the microalgal biodiesel tested here. Therefore, in order to achieve similar PM (particulate matter) emission benefits for microalgal biodiesel likewise to conventional biodiesel, fatty acid methyl esters (FAMEs) with high amounts of polyunsaturated long-chain fatty acids (≥C20) may not be desirable in microalgal biodiesel composition.

Impact of metabolic syndrome in acute myocardial infarction at hospital.

The study was aimed to find out the impact of metabolic syndrome in patients with acute myocardial infarction during hospital stay. This prospective study was carried out in coronary care unit, Mymensingh Medical College Hospital from August 2009 to May 2010. Patients were followed up for minimum 3 days to maximum 6 days after admission. Variables of this study were age, sex, smoking, anterior AMI, inferior AMI, Non STEMI, hyperglycemia, low high density lipoprotein (HDL), raised blood pressure, high triglyceride (TG), waist circumference, recurrent non fatal MI, heart failure (Killip class), arrhythmia (VT, VF), ejection fraction (EF), family history of cardiovascular (CV) risk factors. Considering inclusion and exclusion criteria total 100 patients were included and divided into two groups, Group A - Acute Myocardial Infarction (AMI) with Metabolic Syndrome (MS) and Group B - Acute Myocardial Infarction (AMI) without Metabolic Syndrome (MS). Investigations included ECG, FBS, fasting lipid profile, cardiac enzyme (troponin I) and echocardiography (2D & M mode). The data were analyzed by computer software SPSS version 12. Chi-square test, t test, ANOVA test was used as test of significance. Among the study population (n=100), female were 12.0%. Mean age of study population was 53.3±10.6 years vs. 47.5±11.3 years. Distribution of metabolic syndrome components in study population, High TG (?150mg/dl) was more prevalent (81.1% vs. 25.8%). Heart failure (Killip class) was significantly more in metabolic syndrome patients than those without metabolic syndrome (46.0 % vs. 20%). LV ejection fraction also lowers in metabolic syndrome patients (46.76±8.34 vs. 50.45±7.50) with MI. Among the components of metabolic syndrome, hyperglycemia had strongest association for development of heart failure (OR 3.05; 95% CI 0.80-12.14).