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Heating of sugarcane juice gives concentrated sugarcane juice (CSJ) which becomes raw material for the production of a variety of value added products. Conventional ways of CSJ production are environment polluting and indulge in huge amount of energy losses. In this study, an attempt is made to obtain final CSJ (98°B) by induction heating (IH) which is environment friendly and causes minimum energy losses. The experiments are performed at constant heat flux (9947.5 W m−2) on samples of sugarcane juice having 14.2°B, 18.8°B, 23.9°B, and 27.4°B values of initial brix contents. Thermo-enviro-economic analyses are carried out for the experiments conducted on given samples. The results concluded that time required for obtaining final CSJ decreases and evaporation rate increases with increase in initial brix value of sugarcane juice. The energy required for obtaining final CSJ from sugarcane juice of 27.4°B is 683.43 kJ which is 154.3% less as compared to that of fresh sugarcane juice heating with 14.2°B. The environmental parameters have no discernible effects of initial brix value while economic factors were improved. IH is observed thermally and environmentally beneficial with lower costs of CSJ production from the juice of higher initial brix contents. [ABSTRACT FROM AUTHOR]

This article is a comparison of the date fruits drying performance of two most simple and common type of solar dryers. A simple even span type forced convection greenhouse dryer (FCGHD) and a forced convection cabinet solar dryer (FCCSD) were developed and tested under the climate of Hisar, India. The average values of convective heat transfer coefficients (HTC) were calculated as 0.46 and 0.53 W m−2 °C−1 for FCGHD and FCCSD, respectively. The respective average evaporative HTC was evaluated as 64.58 and 276.06 W m−2 °C−1. The drying efficiency and specific energy consumption for date fruits drying under FCCSD were, respectively, 55.2% higher and 37.87% lower than that of FCGHD. Amongst seven considered thin layer drying models, Midilli–Kucuk model showed the highest commensuration to the experimentally evaluated drying data of moisture ratio for date fruits. Higher values of effective moisture diffusivity and lower values of activation energy were observed under FCCSD. The economic prospective of both the drying arrangements has also been presented. [ABSTRACT FROM AUTHOR]

Experiments have been performed on an innovative stepped solar distillation-cum-active drying unit (SSD-ADU). The basin of the distillation unit is made in the stepped form and its underneath part works as a drying unit which is integrated with a solar flat plate collector. Thermal analysis of the SSD-ADU has been performed at water flow rates of 50 and 65 mL min−1 in the distillation unit for drying ginger. The developed unit has been found to perform better at lower water flow rate for which the drying of bitter gourd and potato slices has also been tested. The average values of internal and external heat transfer coefficients at lower flow rate for distillation unit are found to be 121.20 and 18.95 Wm−2 °C, respectively. The average values of convective heat transfer coefficients for the drying of ginger, bitter gourd and potato slices have been evaluated as 5.24, 4.67 and 5.46 Wm−2 °C, respectively. The energy efficiency, exergy efficiency and daily distillate output of the distillation system at lower flow rate have been observed 15%, 28% and 12% higher than at other given flow rate. Experimental uncertainty, efficiency of solar collector and cost analysis of SSD-ADU have also been evaluated. [ABSTRACT FROM AUTHOR]

This article investigates the visualizations of heatlines in a natural convection magnetohydrodynamic flow from a vertical cylinder via heat function concept. Fluid is electrically conducting in the existence of an applied magnetic field. The constitutive equations of time-dependent, coupled and highly nonlinear Jeffrey fluid model are evaluated mathematically by utilizing well-organized unconditionally stable finite-difference Crank–Nicolson method. Simulated results are given for several values of Deborah number and Hartmann number to present interesting aspects of the solution of the flow variables, friction factor and heat transfer rate. Results specify that required time to achieve time-independent state rapidly rises with the boosting values of Hartmann number. Boundary-layer flow visualization has been made using heatlines, isotherms and streamlines to perceive the understanding of heat and fluid flow. It is noticed that heat function value reduces for augmenting Hartmann number and also for all smaller physical parameter values and these heatlines become closer to the hot wall. It is also remarked that the hydromagnetic flow-field profiles concerning the Newtonian fluid show a different pattern from that of non-Newtonian Jeffrey fluid. [ABSTRACT FROM AUTHOR]

This article studies the pattern of heat lines in free convection non-Newtonian flow from a semi-infinite vertical cylinder via Bejan's heat function concept. The viscoelastic Jeffrey fluid model is employed. The time-dependent, coupled, nonlinear conservation equations for momentum and energy (heat) are solved computationally with the unconditionally stable finite difference Crank–Nicolson method. Extensive graphical results are presented for the influence of Deborah number (viscoelastic parameter) and Prandtl number (with ranges 0–0.8 and 0.68–7.2, respectively) on thermal and flow characteristics including time histories of overall skin friction and heat transfer rate. Lower values of Deborah number indicate that the material acts in a more fluid-like manner, whereas the higher values of Deborah number correspond to the material showing characteristics more associated with a solid. The solutions indicate that the time taken for the flow-field variables to achieve the steady state is increased with higher values of Deborah number. Boundary flow visualization is presented using heat lines, isotherms and streamlines. It is observed that as Deborah number increases the intensity of heat lines increases and they tend to deviate from the hot cylindrical wall. Furthermore, the flow-field variables for the Newtonian fluid case exhibit a significantly different pattern from that of Jeffrey fluid. [ABSTRACT FROM AUTHOR]

Wood, one of the flammable material, was treated with aqueous solution of guanidine nitrate (GUN) and also with small amount of bases like N, N-dimethylformamide, 4-dimethylaminopyridine, pyridine, and triethylamine in the treating solution. These bases catalyze the impregnation of GUN as indicated by increase in mass gain percentage, elemental analysis, and scanning electron microscopy. To study their thermal behavior, dynamic thermogravimetry (TG) and derivative thermogravimetry (DTG) analysis under nitrogen atmosphere have been applied from ambient temperature to 973 K on all samples, at multiple linear heating rates 2.5, 5, 10, and 20 K min. Non-isothermal, 'model free' iso-conversional multiple heating rate methods, Ozawa-Flynn-Wall (O-F-W) and modified Coats-Redfern are used to calculate activation energy of samples. The activation energy of samples is found in the range 109-208 kJ mol. Thermal parameters like overall pyrolysis duration, maximum mass loss rate, corresponding to DTG peak maximum and percentage char yield calculated at 873 K from TG curves are used to appraise the flammability of samples. Also, flammability of samples is determined by reliable methods namely limiting oxygen index and underwriters laboratories 94 (UL 94) test. The aforesaid study indicates that base catalyzed impregnated samples are less flammable than those impregnated with only GUN and untreated ones. [ABSTRACT FROM AUTHOR]

An energetic composite of an octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine with a polymer matrix is generally developed to reduce sensitivity, improve mechanical strength and furnish engineering shape. A hydroxyl-terminated polybutadiene (HTPB) and various curatives, namely methylene diphenyl diisocyanate (MDI), isophorone diisocyanate (IPDI), toluene diisocyanate (TDI) and trimethyl-hexamethylene diisocyanate (TMDI), were mixed in 1:1 [NCO]/[OH] equivalent ratio to form polyurethane, and these samples were designated by HTPB/MDI, HTPB/IPDI, HTPB/TDI and HTPB/TMDI, respectively. The four kinds of energetic composites were prepared by mixing of an energetic HMX with various HTPB/MDI, HTPB/IPDI, HTPB/TDI and HTPB/TMDI matrices. These composites were studied for the thermal stability by employing thermogravitry analysis (TGA) and found to be almost similar. The kinetic parameters of all kinds of composites were investigated through the isoconversional Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS) methods for the first and second stages of the thermal decomposition using TGA data. The results of the activation energy obtained from the FWO method were analogous to those values obtained from the isoconversional KAS method. In addition, the kinetic parameters were also investigated through isoconversional KAS method using DSC data. The overall values of the activation energy of the HMX/HTPB/MDI, HMX/HTPB/IPDI, HMX/HTPB/TDI and HMX/HTPB/TMDI samples were varied in a range of 168–263, 277–409, 210–421 and 206–324 kJ mol−1 at a constant value of conversion (α = 0.1–0.9), respectively. The results indicated that there was significant variation in the activation energy with varying curative groups in the HTPB-based PU matrices. The compensation effect method was used to calculate the pre-exponential factor. The energetic composites were also investigated for the thermodynamic parameters for formation of the activated complexes and are discussed. [ABSTRACT FROM AUTHOR]

A series of new unsymmetrical 2,5-disubstituted 1,3,4-oxadiazoles ( 3a- d) has been synthesized to evaluate their antibacterial and thermal properties. All compounds have been tested for their in vitro antibacterial activity against two Gram-positive bacteria namely, Staphylococcus aureus and Bacillus subtilis. Among the tested compounds, compound 2-(4-chlorophenyl)-5-(thiophen-2-yl)-1,3,4-oxadiazole ( 3c) has been found to be most potent member having minimum inhibitory concentration. Thermal stability and melting point of compounds have been studied by TG and DSC analysis in air atmosphere at heating rate of 10 °C min. Thermal degradation kinetics of the most potent antibacterial compound 3c has been carried out by multiple heating rate model free kinetic methods namely, Ozawa-Flynn-Wall, modified Coats-Redfern, and Kissinger. [ABSTRACT FROM AUTHOR]