• Energy Research
• IN close
• RU close
• Indian Institutes of Technology close

Abstract In this communication, a mathematical model is presented to predict the thermal performance of a spherical solar still. The analysis is based on the heat and mass transfer relationships by Dunkle (1961) which have been modified empirically so as to validate the experimental results of Menguy et al. (1980). Numerical calculations have also been made to study the effect of the absorptivity of the basin liner on the distillate yield of the still

Photoconductive antennas (PCAs) are among the most conventional devices used for emission as well as detection of terahertz (THz) radiation. However, due to their low optical-to-THz conversion efficiencies, applications of these devices in out-of-laboratory conditions are limited. In this paper, we report several factors of enhancement in THz emission efficiency from conventional PCAs by coating a nano-layer of dielectric (TiO2) on the active area between the electrodes of a semi-insulating GaAs-based device. Extensive experiments were done to show the effect of thicknesses of the TiO2 layer on the THz power enhancement with different applied optical power and bias voltages. Multiphysics simulations were performed to elucidate the underlying physics behind the enhancement of efficiency of the PCA. Additionally, this layer increases the robustness of the electrode gaps of the PCAs with high electrical insulation as well as protect it from external dust particles.

The convective heat transfer in microchannels with the use of nanofluids has proved to be a potential candidate for cooling of micro-electromechanical system devices. The current research article presents the experimental study on fluid flow and heat transfer characteristics of [Formula: see text]/water nanofluid in a microchannel under thermally developing laminar flow at Reynolds number ranging from 300 to 1000. The experimental set-up of a circular microchannel test section with an inner diameter of [Formula: see text] and length of [Formula: see text] is fabricated to conduct the experimental study. The effect of nanoparticle concentration ([Formula: see text]), Reynolds number ([Formula: see text]) on fluid flow and heat transfer characteristics of [Formula: see text]/water nanofluid have been measured and compared with that of distilled water (DW). The results indicate that the maximum enhancement in local heat transfer coefficient is achieved up to [Formula: see text], while friction factor is achieved up to [Formula: see text] for [Formula: see text]/water nanofluid with nanoparticle concentration of [Formula: see text] as compared to DW. The results showed that the performance evaluation criterion of [Formula: see text]/water nanofluid is greater than unity ([Formula: see text]), implying the benefits of nanofluids as compared to DW. Moreover, the predicted data obtained by the present proposed correlations for friction factor and local Nusselt number using [Formula: see text]/water nanofluid show reasonably good agreement with the deviations of [Formula: see text] and [Formula: see text], respectively, with the numerical data as compared to the predicted data obtained by the existing correlations available in the literature.

Nowadays, increasing population, widespread urbanization, rise in living standards together with versatile use of polymers have caused non-biodegradable polymeric wastes affecting the environment a chronic global problem, simultaneously, the existing high energy demand in our society is a matter of great concern. Hence forth, this review article provides an insight into the technological approach of pyrolysis emphasizing catalytic pyrolysis for conversion of polymeric wastes into energy products and presents an alternative waste management technique which is a leap towards developing sustainable environment. Pyrolysis of waste non-biodegradable polymer materials involves controlled thermal decomposition in the absence of oxygen, cracking their macromolecules into lower molecular weight ones, resulting into the formation of a wide range of products from hydrogen, hydrocarbons to coke. Nanocatalyzed pyrolysis is a recommended solution to the low thermal conductivity of polymers, promoting faster reactions in breaking the C-C bonds at lower temperatures, denoting less energy consumption and enabling enhancement in the process selectivity, whereby higher value added products are generated with increased yield. Nanotechnology plays an indispensable role in academic research as well as in industrial applications. Existing reviews illustrate that one of the oldest application field of nanotechnology is in the arena of nanocatalysis. Nanocatalysis closes the gap between homo and heterogeneous catalyses while combines their advantageous characteristics and positive aspects, reducing the respective drawbacks. During the current nanohype, nanostructured catalysts are esteemed materials and their exploration provide promising solutions for challenges from the perspective of cost and factors influencing catalytic activity, due to their featured high surface area to volume ratio which render enhanced properties with respect to the bulk catalyst.

Abstract In this communication, an analysis of multipass air heating system has been carried out bv incorporating the effect of reflector, duct length, thermal storage and movable insulation for various applications. The analysis is based on energy balance equations for different component of the system. In order to have the parametric study, numerical computation has been done for a typical day of the month of June and December for Delhi climatic conditions. It has been observed that design parameters can be optimized by the proposed theory

Surfactant-modified alumina (SMA) was prepared and used for the removal of Mn(II), Ni(II), and Cu(II) from aqueous environment. Batch studies were conducted to find out optimum pH of the medium, adsorbent dose of SMA, and contact time. They were further optimized using response surface methodology (RSM). In the present study, a three-factor, three-level Box–Behnken experimental design was used to derive a second-order polynomial equation and construct three-dimensional (3D) surface plots and two-dimensional (2D) contour plots to examine the response. The level of significance for each independent variable and their interaction effects were examined by means of analysis of variance (ANOVA), F test, and Student’s t test results. In addition, the percentage effects of the different factors and their interactions on the removal efficacy were also investigated by plotting a Pareto chart. The models were validated for accurate prediction of the percentage (%) removal by performing numerical optimization. The optimum values of three tested variables were determined at pH 6.2, 8.2, and 5.3; adsorbent dose = 20, 5, and 4 g/L; and contact time = 30, 60, and 75 min for the adsorption of Mn(II), Ni(II), and Cu(II) ions, and the corresponding removal efficiency was found to be 77.04, 93.83, and 97.23 %, respectively.

Abstract Based on the periodic solution of the heat conduction equation, an analysis has been developed to study the thermal performance of a simple domestic solar water-heating system consisting of a thermal-trap solar-energy collector, connected to a water tank. To study the effects of typical parameters such as the thickness of the trap material and the presence/absence of the glass cover on the thermal performance, numerical calculations have been performed to correspond to the daily variations of the ambient temperature and solar intensity on a typical cold winter day in New Delhi.