Papers by Prof. (Dr.) Manmatha K Roul
Ceramics International, 2013
Density functional theory, density functional perturbation theory, and the Debye model have been ... more Density functional theory, density functional perturbation theory, and the Debye model have been used to investigate the structural, elastic, sound velocity, and thermodynamic properties of AlN with cubic rock-salt structure under high pressure, yielding the equilibrium structural parameters, equation of state, and elastic constants of this interesting material. The isotropic shear modulus, Pugh ratio, and Poisson's ratio were also investigated carefully. In addition, the longitudinal, transverse, and average elastic wave velocities, phonon contribution to the thermal conductivity, and interesting thermodynamic properties were predicted and analyzed in detail. The results demonstrate that the behavior of the elastic wave velocities under increasing hydrostatic pressure explains the hardening of the corresponding phonons. Based on the elastic stability criteria under pressure, it is found that AlN with cubic rock-salt structure is mechanically stable, even at pressures up to 100 GPa. Analysis of the Pugh ratio and Poisson's ratio revealed that AlN with cubic rock-salt structure behaves in brittle manner.
Advances in numerical analysis of ranque-hilsch vortex tube: A review
AIP Conference Proceedings, Dec 31, 2022
Impact of flapping trajectory and foil gap on induced thrust of a flapping foil
Ocean Engineering
A Comprehensive Review on Performance Evaluation Methods of Biomass Cook Stoves
CRC Press eBooks, Apr 12, 2023
A short review on cooling process using compressed cold air by vortex tube in machining
Materials Today: Proceedings
Experimental Investigation of Natural Convection Heat Transfer in Heated Vertical Tubes with Discrete Rings
Experimental Techniques, 2017
Natural convection heat transfer from heated vertical pipes has been investigated experimentally.... more Natural convection heat transfer from heated vertical pipes has been investigated experimentally. The pipes are open-ended and circular in cross section. The test sections are electrically heated imposing the circumferentially and axially constant wall heat flux. The outer surface of the test section is insulated and heat is allowed to dissipate from the internal surface. Experiments are carried out for four different channels of 45 mm internal diameter and 3.8 mm thickness with length varying from 450 mm to 850 mm. Ratios of length to diameter of the channel are taken as L/D = 10, 12.22, 15.56, and 18.89. Wall heat fluxes are maintained at q// = 250 to 3341 W/m2. Experiments are also carried out on intensified tubes of the same geometrical sizes with the discrete rings of rectangular cross section provided on the internal surface. Thickness of the rings are taken as t = 4, 6 and 8 mm; step size (s) of the rings are varying from 75 mm to 283.3 mm and the other ratios are taken as s/D = 1.67 to 6.29, t/D = 0.088 to 0.178 and s / t = 9.38 to 70.82. The effects of L/D ratio, ring thickness, ring spacing and wall heating conditions on local steady-state heat transfer phenomena are studied. A correlation is developed for average Nusselt number and modified Rayleigh number and another correlation is also developed for modified Rayleigh number and modified Reynolds number. These correlations predict the data accurately within ±10% error.
Performance Evaluation of an Improved Biomass-Fired Cook Stove
CRC Press eBooks, Apr 12, 2023
Experimental study of fluid flow properties at exit of the heated tube subjected to natural convection heat transfer
Materials Today: Proceedings
Heat Transfer-Asian Research, 2017
A super fast reactor is a fast spectrum, supercritical, watercooled reactor. This paper represent... more A super fast reactor is a fast spectrum, supercritical, watercooled reactor. This paper represents CFD analysis of heat transfer in hexagonal subchannels of super fast reactor using FLUENT in ANSYS. The numerical simulation of grid stability was done by considering different mesh sizes and the turbulence model for heat transfer of supercritical water was also carried out and compared with the experimental data. RNG k-turbulence model with enhanced wall treatment was considered for simulations. Heat transfer and heat generation rate analysis of the outer surface rod wall is carried out with different subchannels by changing various parameters like boundary conditions and pitchto-diameter ratio. The analyses reveal that the outer surface of the rod wall temperature decreases with increase in pitch-to-diameter ratio. Maximum coolant temperature rises in edge subchannels more than corner subchannels.
Journal of The Institution of Engineers (India): Series A
India is the second most populous country in the world and relies heavily on agriculture as its m... more India is the second most populous country in the world and relies heavily on agriculture as its main source of income. The combination of agriculture and technology is needed to accelerate the development of agriculture, especially in rural areas, to increase productivity, e ciency and pro tability. Application of technology in agriculture will enhance the farmers to involve in their occupation. Agriculture mainly consists of eld grounding, transplantation, harvesting. In each steps of agriculture irrigation is the main requirement. Farmers are spending more to irrigate their farm for agriculture. So application of technology on irrigation is the most important requirement to sustain the farmers. In this work a pendulum operated irrigation model is presented. The designed model is required to attach with the hand pump. The developed system will work without any external source of power, which will provide maximum pro t to farmers.
Sādhanā
Determination of heat transfer characteristic has been analysed theoretically using the heat prop... more Determination of heat transfer characteristic has been analysed theoretically using the heat propagation phenomena of methane-air-premixed turbulent flames impinging on plane surfaces. The heat flux propagation on the plane surface completely depends on the distance between the plate and nozzle, Reynolds number and equivalence ratio (ER). The solution of the differential equation related to conservation of momentum, mass and energy has been analysed. The radiative heat transfer model has been designed using several radiation models and the turbulence model is analysed by the help of RNG k-e turbulence model. In the response plot it is found that heat flux increases progressively with the radial distance towards the centre of the plate to achieve the maximum value at a position a bit away from stagnation point and thereafter it reduces. It has also been exhibited that when the distance of the target plate increases, the location of the maximum value of the local heat flux approaches the stagnation point. The dependence of heat transfer phenomena on ER, Reynolds number and separation of the plate from the nozzle has been studied.
Electrical Science & Engineering
The comparison between experimental and theoretical heat transfer inside heated vertical channels... more The comparison between experimental and theoretical heat transfer inside heated vertical channels that dissipate heat from the internal surface with and without internal rings is studied. The experimental setup consists of a circular pipe which is heated electrically by providing constant heat flux on the wall. The theoretical and experimental analysis is conducted in several pipes of same diameter but different lengths. The length of the pipe varies from 450 mm to 850 mm. The length to diameter ratios are taken as L/D = 10, 12.22, 15.56, and 18.89. The value of imposed heat flux varies from 250 to 3340 W/m2. The internal ring thickness varies from 4 mm to 8 mm. separation distance between the internal rings varies from 75mm to 300 mm. The theoretical results are compared with experimental data to ascertain numerical accuracy of the method. The effects of L/D ratio, thickness of internal rings and separation distance on the heat transfer performance are studied. The experimental re...
Natural convection heat transfer through heated vertical tubes with discrete rings
Fig. 1(a) Idealized course of boundary stream lines and (b) pressure profile for a sudden expansion.
Experimental Investigation Natural Convection Heat Transfer Through Heated Vertical Tubes
Exergy analysis for biomass co-firing coal fuel based thermal power plant
Mathematical Modeling of Two-Phase Pressure Drop due to Flow of Oil-Water Emulsions through Sudden Contraction
Pressure drop through sudden contractions were numerically investigated for two-phase oil/water e... more Pressure drop through sudden contractions were numerically investigated for two-phase oil/water emulsions. Twophase computational fluid dynamics (CFD) calculations, using Eulerian-Eulerian model were employed to calculate the velocity profiles and pressure drop across sudden contraction. The realizable per-phase k turbulence model has been used as a closure model for turbulent flow. The pressure loss was determined by extrapolating the computed pressure profiles upstream and downstream of the contraction. From the pressure-loss and velocity data, the loss coefficients were obtained. The oil concentration was varied over a wide range of 0-97.3 % by volume. The loss coefficients for the emulsions were found to be independent of the concentration and type of emulsions. The numerical results were validated against experimental data from the literature and were found to be in good agreement.
Heat Transfer due to Impinging Flames on Plane and Curved Surfaces
Pressure drop across sudden contractions in pipes are numerically investigated for two-phase air/... more Pressure drop across sudden contractions in pipes are numerically investigated for two-phase air/water mixtures. Two-phase computational fluid dynamics (CFD) calculations using Eulerian-Eulerian model are employed to calculate the velocity profiles and pressure drop across sudden contraction. The pressure drop at the contraction plane has been obtained by extrapolating the computed linearized pressure profiles upstream and downstream of the contraction, to the contraction plane. Two area ratios of 0.0568 and 0.1804 have been considered. Computations are performed with singlephase flow of water and air, and two-phase mixtures. The effect of various parameters such as mass flux, mass flow quality, area ratios, flow directions (horizontal/vertical), system pressures etc on the two-phase pressure drops have been studied. The numerical results are validated against experimental data from the literature and are found to be in good agreement.
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Papers by Prof. (Dr.) Manmatha K Roul