Statistical approach on 3D hydromagnetic flow of water-based nanofluid between two vertical porous plates moving in opposite directions

The nanofluid flow between two plates is a common topic of research. However, studies dealing with the flow between two vertical plates moving in different directions have not been largely accounted for. The main aim of this study is to analytically and statistically investigate the MHD flow of water-based nanofluid between two vertical porous plates moving in opposite directions using perturbation technique and multiple linear regression, respectively. The consequence of various parameters on concentration, temperature, and velocity are examined via graphs using MATLAB software. It is observed that the main flow velocity profile is greater when the magnetic field is applied on the upward moving plate as compared to the main flow velocity when the magnetic field is applied on the downward-moving plate. The physical quantities are scrutinized using statistical tools like probable error and multiple linear regression and an excellent agreement is noted. It is noted that the Nusselt number is highly positively correlated with the injection parameter and highly negatively correlated with nanoparticle volume fraction. Furthermore, the simultaneous effects of parameters on drag coefficients are studied with the aid of three-dimensional surface plots.     

Temperature dependence of the optical transitions in CdTe thin film – Investigation with photoresponse spectra

The CdTe thin films have been prepared by electrochemical method from a bath solution containing cadmium sulfate and tellurium dioxide. Schottky devices of the type Au/CdTe were prepared and the spectral response of the device has been investigated. The direct and indirect transitions in the 1.3–1.6 eV region were calculated from the normalized spectral response data. The temperature dependence of the band gap have been investigated and correlated with the theory. The band gap of CdTe at absolute zero temperature is estimated as 1.61 eV and that the rate of change of E_g with temperature is calculated as −0.4 meV/K. The 1.407 eV indirect transition involves a trap level near the conduction band edge. The indirect transition also exhibits temperature dependence.     

Economic and energy efficiency of salvaging biomass from wildfire burnt areas for bioenergy production in northwestern Ontario: A case study

Wildfire burnt forest biomass can be salvaged as feedstock for bioenergy power generating stations. Despite availability of such forest biomass in northwestern Ontario, its procurement has generally been considered uneconomic and no studies have looked into the cost of harvesting, processing, and transporting the burnt material for bioenergy production. In order to meet the demand of biomass for proposed and existing power generating stations using renewable fuels, a standard costing model is used to determine the feasibility of procuring biomass from burnt areas using a full-tree to roadside, roadside grinder to mill system. The case-study was conducted at the Hogarth Plantations near Thunder Bay, Ontario, Canada. The total cost incurred for processing and delivery of biomass from wildfire burnt area with a hauling distance of 7 km and total trip cycle time of 2.55 h was found to be $29.65 gt^?1, with net energy content of 11.4 GJ gt^?1. The total procurement cost depends on the hauling distance and a linear relationship between the two was established. The energy analysis found a net energy output to input ratio of 35:1 for the operation.     

Physical properties of the CNT:TiO2 thin films prepared by sol–gel dip coating

Uniform and highly adherent thin films of CNT:TiO₂ were synthesized by sol–gel dip coating method. Both TiO₂ and CNT:TiO₂ films showed very identical structural characteristics and no significant changes in the lattice values were observed. The crystalline size decreased from 20 nm for TiO₂ film to 17 nm for the 4%CNT:TiO₂ film. The film surface was very smooth and compact, as indicated by the roughness data obtained from AFM measurements; the root mean square (rms) average of the roughness was as low as 3 nm. The HRTEM showed that the CNTs are embedded in the matrix of TiO₂ indicating the formation of a composite. In Raman spectra the characteristic vibrations of the TiO₂ are identified, the increase in the FWHM of main anatase peak (144 cm^?1) in the case of the 4%CNT:TiO₂ film is interpreted as due to the incorporation of CNTs in the film. At the wavelength of 600 nm the refractive index of pure TiO₂ was 2.07 and the 4%CNT:TiO₂ showed a value of 2.29. The photoresponse curves showed typical features of charge trapping centers in the band gap of the films.     

Tin doping in spray pyrolysed indium sulfide thin films for solar cell applications

This paper presents studies carried out on tin-doped indium sulfide films prepared using Chemical Spray Pyrolysis (CSP) technique. Effect of both in-situ and ex-situ doping were analyzed. Ex-situ doping was done by thermal diffusion, which was realized by annealing Sn/In₂S₃ bilayer films. In-situ doping was accomplished by introducing Sn into the spray solution by using SnCl₄·5H₂O. Interestingly, it was noted that by ex-situ doping, conductivity of the sample enhanced considerably without affecting any of the physical properties such as crystallinity or band gap. Analysis also showed that higher percentage of doping resulted in samples with low crystallinity and negative photosensitivity. In-situ doping resulted in amorphous films. In contrast to ex-situ doping, ‘in- situ doping’ resulted in widening of optical band gap through oxygen incorporation; also it gave highly photosensitive films.     

Strategies for stationary and portable fuel cell markets

In the future, hydrogen-based stationary and portable fuel cell systems can help supply some or all of the power demanded with additional advantages of higher reliability, lower emissions, independence from the general grid, and cogeneration capability. In order to understand how to prepare the future for this technology, this paper describes a thorough investigation of past alternative stationary and portable power projects in order for an assessment of the opportunities for stationary and portable fuel cell markets, as well as interactions with transportation hydrogen systems. The lessons learned from the programs are used to establish best practices and recommendations for a hydrogen strategy that addresses opportunities for hydrogen in power generation systems, as well as to make recommendations for market transformation within the hydrogen fuel cell industry.     

Performance of Counterflow Microchannel Heat Exchangers Subjected to External Heat Transfer

This article analyzes the effect of external heat transfer on the thermal performance of counterflow microchannel heat exchangers. Equations for predicting the axial temperature and the effectiveness of both fluids as well as the heat transferred between the fluids, while operating under external heating or cooling conditions, are provided in this article. External heating may decrease and increase the effectiveness of the hot and cold fluids, respectively. External cooling may improve and degrade the effectiveness of the hot and cold fluids, respectively. For unbalanced flows, the thermal performance of the microchannel heat exchanger subjected to external heat transfer depends on the fluid with the lowest heat capacity. At a particular number of transfer units (NTU), the effectiveness of both the fluids increased with decrease in heat capacity ratio when the hot fluid had the lowest heat capacity. When the cold fluid had the lowest heat capacity, the effectiveness of both fluids increased with decrease in heat capacity ratio at low values of NTU but at high values of NTU the effectiveness increased with increase in heat capacity ratio. A term called the “performance factor” has been introduced in this article to assess the relative change in effectiveness due to external heat transfer.     

Outgassing of ZrF4-Based Glasses

The nature and quantities of the chemical species evaporating from the surface of fluorozirconate glasses heated to above T_g were investigated. ZrF4 vaporized from a ZBLAN glass whereas ZrF₃. ZrF₂ and ZrF vaporized from a ZBL glass. Other gases found include HF, HCl, O₂, CO₂, and atomic fluorine.     

The influence of oxidation on the structure and strength of graphite—II: Materials of different impurity content

Six polycrystalline graphites were manufactured to contain specific impurities, iron, vanadium and calcium, with two different concentrations. They were then oxidized in either dry air, CO₂ or H₂O so as to produce a uniform gasification profile within the samples and were tested for loss of compressive strength and Young's modulus. Mercury porosimeter measurements and scanning electron microscope observations were also made. Materials containing calcium suffered the greatest loss of mechanical properties for a given weight loss, with calcium producing the greatest catalytic effect for the graphite—H₂O reaction. For the materials doped with Ca and Fe there appeared to be little or no effect of impurity concentration on strength loss as a function of burn-off. Microscopic observations showed that the degradation of mechanical properties was due to gross gasification of the binder together with some weakening of filler particles.