Forced boiling of nanofluids, effects of contact angle and surface wettability

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.Nanofluids are the suspension of ultra fine particles in a conventional base fluid which tremendously changes the heat transfer characteristics of the original fluid. In this paper the boiling characteristics of different nanofluids was studied numerically using a CFD approach. Dispersions of Al2O3, SiO2, and ZrO2 nanoparticles in water at different concentrations (0.1, 0.01 and 0.001% by volume) have been used. Effects of some noticeable parameters such as nanoparticle concentration and temperature profile on the critical heat flux (CHF) have been investigated. The results of CFD simulation based on two-phase models were compared with experimental data. Boiling curves and critical heat flux were measured for the base fluid and the nanofluids. Based on the simulation results, it was concluded that the using of the Zirconium oxide (0.001%) led to modest (up to 31%) increase in the CHF. The minimum enhancement belongs to the aluminum oxide (0.1%) which increases the critical heat flux up to 11%. According to the experimental results, despite of expectation, addition of the nanoparticles causes decreasing the boiling heat transfer coefficient. This reduction is related to the changing of the surface characteristic causing by depositing the nanoparticles. In the Al2O3/water and SiO2/water nanofluids, the surface contact angle increases with increase in the nanoparticle volume fraction, so the CHF decreases

EFFECT OF SILVER NANOPARTICLES, SPERMINE, SALICYLIC ACID AND ESSENTIAL OILS ON VASE LIFE OF Alstroemeria

In this study, effects of different concentrations of silver nanoparticles (NS), salicylic acid (SA), spermine (SP), dill (AN), and cumin (CM) essential oils are investigated on physiological and microbiological traits of alstroemeria (Alstroemeria hybrida) cut flowers during a preharvest and postharvest application. The study was performed as a factorial experiment based on a randomized completely design with three replications. During the experiment the vase life of cut flower was evaluated in terms of chlorophylls a, b and total, SOD, MDA, stem end bacterial colonies and bacterial identification. The results showed that using high concentrations of nanosilver (NS2) increased significantly the vase life of cut Alstroemeria in preharvest and postharvest. 11 colonies of bacteria were identified in stem end of cut alstroemeria flowers

A Comparative Study of Energy Use and Greenhouse Gas Emissions of Canola Production

I n this research, the energy flow and production energy indices of canola cultivation in Trakya province of Turkey, Golestan and Mazandaran provinces of Iran were compared. Diesel fuel and chemical fertilizer inputs were the highest consumer of energy in the production of canola in these three regions. The results indicated that despite the higher energy use of machinery in Trakya province of Turkey, the energy use of diesel fuel in this province is less than the energy consumed in the two northern provinces of Iran, which could be due to available old machines for the production of canola in Mazandaran and Golestan provinces. Total greenhouse gas emissions of canola production for these regions were computed 562.85, 652.86 and 887.30 kgCO 2eq ha-1, respectively. The inputs of chemical fertilizer and diesel fuel in canola production produced the highest percentage of gas emissions in these three areas. Energy consumption for potential feedstock production for one kg production of biodiesel fuel in these provinces was calculated as 14.76, 20.66 and 37.77 MJ, respectively. The amounts of greenhouse gas emissions for potential feedstock production for one kg production of biodiesel were obtained 0.45, 0.76 and 1.17 kgCO 2eq for Trakya, Golestan and Mazandaran provinces, respectively

CFD Study of Calibration Factor for Cross Correlation Based Ultrasonic Flowmeter at Different Upstream Pipe Lengths

Despite lots of researches on the transit-time and Doppler flowmeter technologies, few researches have been done on ultrasonic cross correlation flowmeter technology. Since the mechanism of the ultrasonic cross correlation flowmeter (UCCF) differs from other ultrasonic flowmeter technologies, it strongly requires individual investigations. The upstream straight pipe length is an important item that strongly affects the UCCF accuracy. Determination of proper calibration factor concerning upstream pipe length could incredibly improve the measurement precision. In the present study, the Computational Fluid Dynamics (CFD) simulation was conducted and the water flow inside a pipe without any flow disturbances (e.g., valve, fitting, or bend) was simulated to investigate the calibration factor for the UCCF at different upstream straight pipe lengths and different Reynolds numbers (from 76,600 to 383,400). For accurately predicting the turbulent flow behavior, Reynolds Stress Model (RSM) was used in this study. The results indicated that by increasing the upstream pipe length up to approximately 25 times pipe diameter, the required calibration factor decreases, then increases, and finally remains constant at lengths greater than 40 times pipe diameter. Eventually, a proper correction factor on the calibration curve was developed at different flow Reynolds numbers, for the first time, in order to modify the calibration curve at various upstream pipe lengths

A Comparative Study of Energy Use and Greenhouse Gas Emissions of Canola Production

I n this research, the energy flow and production energy indices of canola cultivation in Trakya province of Turkey, Golestan and Mazandaran provinces of Iran were compared. Diesel fuel and chemical fertilizer inputs were the highest consumer of energy in the production of canola in these three regions. The results indicated that despite the higher energy use of machinery in Trakya province of Turkey, the energy use of diesel fuel in this province is less than the energy consumed in the two northern provinces of Iran, which could be due to available old machines for the production of canola in Mazandaran and Golestan provinces. Total greenhouse gas emissions of canola production for these regions were computed 562.85, 652.86 and 887.30 kgCO2eq ha -1 , respectively. The inputs of chemical fertilizer and diesel fuel in canola production produced the highest percentage of gas emissions in these three areas. Energy consumption for potential feedstock production for one kg production of biodiesel fuel in these provinces was calculated as 14.76, 20.66 and 37.77 MJ, respectively. The amounts of greenhouse gas emissions for potential feedstock production for one kg production of biodiesel were obtained 0.45, 0.76 and 1.17 kgCO2eq for Trakya, Golestan and Mazandaran provinces, respectively. Abstract International Journal of Agricultural Management and Development (IJAMAD

Effect of salicylic acid and progesterone on physiological characteristics of Kentucky bluegrass under salinity stress

Salinity is one of the most important limiting factors in plant growth. It is also a predominant constraint that impairs grass growth and quality. Plant hormones play important roles in the capability of plants to adapt to environmental stresses. Hence, the impact of two plant growth regulators (PGRs) i.e. salicylic acid (SA) and progesterone (P4) was studied on biological characteristics of Poa pratensis in saline conditions in a greenhouse experimnt. The experimental treatments were composed of salinity at four levels (0, 2, 4, and 6 dS m-1) and six levels of PGRs (control, 1 mg L-1 P4,10 mg L-1 P4, 1 mM SA, 3 mM SA, and 1 mg L-1 P4 + 1 mM SA). The results showed that leaf firing percentage was increased with the excess in salinity, but the use of SA and P4 eased the effects of salinity stress and reduced leaf firing under salinity. 6 dS m-1 and 3 mM SA salinity caused to the maximum electrolyte leakage. The highest relative water content was observed in 4 dS m-1 salinity and 1 mM SA treatment. The highest glycine betaine was related to 6 dS m-1 NaCl and no hormone application. Salinity increased total protein and catalase, and the simultaneous use of P4 and SA exhibited the highest total protein and catalase content, whilst the control plants showed the lowest ones. The application of salinity stress reduced chlorophyll content, but SA and P4 increased it. The application of the two growth regulators improved carotenoid content under salinity stress. Overall, the results showed that the application of SA and P4 improved salinity tolerance and increased pigments and antioxidant enzyme activities

Numerical analysis of nitrogen oxides in turbulent lifted H2/N2 cabra jet flame issuing into a vitiated coflow

Supplementary data are available online at: https://www.sciencedirect.com/science/article/pii/S0360319919311747?via=ihub#appsec1 .This paper gives an in-depth insight into NOX (NO, NO2, and N2O)formation of H2/N2 turbulent Cabra jet flame issuing into a hot vitiated coflow. The joint composition probability density function (PDF)was employed to model the combustion and to specify the characteristics of the flame (i.e., scalar variables, concentration of species etc.). The turbulent transport term was modelled by Reynold-Average-Naiver-Stokes (RANS)SSG and molecular mixing was modelled by modified curl model. A combustion mechanism including 13 species and 34 reactions was employed to define the thermochemical state of the flame. The chemical reaction terms were resolved and accelerated by In Situ Adaptive Tabulation (ISAT). The simulation was performed at different equivalence ratios (ER), fuel jet nitrogen content (YN2,C), coflow (TC)and jet temperatures (TJ), coflow oxygen (YO2,C)and water contents (YH2O,C). Results reveal NOX is composed of 30% NO2 and 70% NO in the burner. Reaction rate analysis at different operating points in the ignition kernel demonstrates that N+OH⇌NO+H and NO2+H⇌NO+OH are dominant reactions in NO formation, while NO+HO2⇌NO2+OH is the main reaction in NO2 formation.Dr. Ahmad Shariati from Petroleum University of Technology, Chairman of Ahvaz Faculty of Petroleum is greatly acknowledged for underwriting this research, as this paper a part of, under his grant number: 9515456

Assessment of genetic diversity among some Iranian hazelnut genotypes using SSR markers

Abstract Studying genetic diversity is a preliminary step for conservation and utilization of germplasm. Talesh hills, located in Guilan province in northern part of Iran, are one of the main areas for natural distribution of hazelnut (Corylus avellana L.). Hazelnut trees in Talesh Mountains are a wild population (land race) and obtained from open-pollinated seedling. In this research, a population including 90 hazelnut samples was studied using 15 microsatellite markers. Totally, 98 polymorphic alleles were detected with an average of 6.53 alleles per locus. The lowest numbers of 3 alleles were observed in CaC-B005 and CaC-C114 and the highest number of 12 alleles in CaC-C101 locus. The average effective number of alleles (3.75), mean expected heterozygosity of (He=0.70) and average observed heterozygosity of (Ho=0.62) were estimated for studied loci. All loci showed high PIC with an average of 0.72 that the highest amount detected in CaC-B011 and CaC-B101 loci with values of 0.85 and 0.84, respectively. A dendrogram was generated by UPGMA clustering method that placed the 90 accessions into 7 main loose groups. According to the results a high genetic diversity was found in the studied population that mainly related to the hazelnut pollination nature that shows sporophytic incompatibility system enhancing out-crossing in natural populations

Improving the Vase life of Cut Carnation ‘Tempo’ (Dianthus carryophyllusL.) Flower by Silver Thiosulphate and Silver Nano-Particles

Nanometer-sized silver particle can be act as an anti-microbial compound. Thus, in this research, the efficacy of silver thiosulphate and silver nano-particles as antimicrobial agents in extending the vase-life of cut carnation flowers was evaluated. A factorial experiment carried out based on randomized completely blocks design with two factors: silver thiosulphate (0, 0.1, 0.2 and 0.3 mM) and silver nano-particles (0, 5, 10 and 15 mg/L). Mean comparison of the data showed that the combined treatments of 0.3 mM silver thiosulphate + 15 mg/L silver nano-particles had the highest vase life, water uptake and super oxide dismutase enzyme. Thus, the mentioned above treatment was proposed to increase prolong vase life and improvement of water relations and control of stem end blockage. Based to results of this study, silver thiosulphate and silver nano-particles can be used for increasing postharvest longevity of cut carnation "Tempo"