Keshav Kant - Academia.edu (original) (raw)

Papers by Keshav Kant

Journal of heat transfer, Mar 1, 2008

The analytical solution for a vertical heated plate subjected to conjugate heat transfer due to n... more The analytical solution for a vertical heated plate subjected to conjugate heat transfer due to natural convection at the surface and conduction below is presented. The heated surface is split into two regions; the uniform heat flux region toward upstream and remaining fraction as the uniform wall temperature region. The fractional areas under the two regions are considered variable. Adopting thermally thin wall regime approximation, the possible solutions were investigated and found to satisfactorily deal with longitudinal conduction and temperature variation in the transverse direction. A test setup was developed and the experiments were conducted to obtain relevant data for comparison with the analytical solutions. The ranges for Rayleigh number and heat conduction parameter (α) during various test conditions were 2×108–6×108, and 0.001–1, respectively. The limiting solutions for stipulated conditions are analyzed and compared with experimental data. Reasonable agreement is observed between the experimental and analytical results.

Gastroenterology research, 2017

With the advent of newer radiological investigations, choledochal cysts are being diagnosed more ... more With the advent of newer radiological investigations, choledochal cysts are being diagnosed more often in present era. These cysts are commonly diagnosed in early childhood and infancy, although some go undetected to be diagnosed in adulthood. These malformations are associated with multiple complications like cholangitis, jaundice, pancreatitis, rupture or even malignancy. Here we describe a post partum female, who was diagnosed to have choledochal cyst during sixth month of pregnancy. She presented with obstructive jaundice in cholangitis and was subjected to endoscopic retrograde cholangiopancreatography (ERCP) with stenting. This female delivered normally at term. She again had jaundice with cholangitis during early post partum period. Endoscopic stenting could be performed. She had features of peritonitis after 1 week of stenting. Investigations were performed and a diagnosis of spontaneous rupture of choledochal cyst was made. She underwent laparotomy and lavage with complete ...

2018 3rd International Conference On Internet of Things: Smart Innovation and Usages (IoT-SIU), 2018

In this paper, we present a 50 V RF power multi-gate LMOS (MG-LMOS) structure on InGaAs with p-ty... more In this paper, we present a 50 V RF power multi-gate LMOS (MG-LMOS) structure on InGaAs with p-type InP substrate. The proposed structure contains three n<sup>+</sup>-polysilicon gate electrodes placed in a trench and n<sup>+</sup> InGaAs layer at bottom of epitaxial layer which act as a drain connected to the vertically extended drain contact at both ends of the device. The MG-LMOS generate parallel current flow through multi-channels in p-base from drain to source. The proposed structure enhances the drain current (I<inf>D</inf>) which provide reduction in specific on-resistance (R<inf>on,sp</inf>) with increase in transconductance (g<inf>m</inf>) leads to provide improvement in cut-off frequency (f<inf>T</inf>) and maximum oscillation frequency (f<inf>max</inf>). The MG-LMOS designed for V<inf>br</inf> of 50 V by using 2-D simulations, provides 3.9 times high I<inf>D</inf>, 5.4 times reduces the R<inf>on,sp</inf>, 5.9 times development in g<inf>m</inf>, 2.1 times increment in f<inf>T</inf>, and 2.5 times improvement in f<inf>max</inf> in comparison with conventional planer LMOS (CP-LMOS) for the equivalent cell pitch.

CRC Press eBooks, May 11, 2023

Printed circuit boards (PCBs)

Written for the Dept. of Chemical Engineering. Typescript. Thesis (Ph.D.) - McGill University. Bi... more Written for the Dept. of Chemical Engineering. Typescript. Thesis (Ph.D.) - McGill University. Bibliography: leaves 282-290.

Experimental Thermal and Fluid Science, 1994

• A study was carried out to observe bubble nucleation and site deactivation mechanisms under equ... more • A study was carried out to observe bubble nucleation and site deactivation mechanisms under equilibrium pool boiling of liquids on single sites. The experiments were conducted with benzene, ethanol, and their mixtures on single sites made of glass. These mechanisms were filmed using a cine camera as the temperature of the boiling liquid was decreased in programmed steps. The experiments showed that the deactivation of a bubble nucleation site in the surface occurred by progressive condensation of vapor within it until the volume of vapor became equal to or smaller than the volume of a spherical bubble of diameter equal to that of the site. Based upon these experimental observations, a site deactivation mechanism is proposed for heterogeneous pool boiling and stability criteria are developed for single cylindrical cavities. The effect of relevant parameters on depth-to-diameter ratio of the sites is also determined.

Indian journal of …, 1992

The pressure drop and drift loss characteristics of cement asbestos dift eliminators (CADE), conc... more The pressure drop and drift loss characteristics of cement asbestos dift eliminators (CADE), concrete drift eliminators (CDE) and cellular type drift eliminators (CTDE) in an evaporative condenser (EC) were experimentally investigated. For CADE and CDE, data were taken for various number of stages, n and for a range of the orientation angle,theta of the eliminator plates. For CTDE, the data were recorded for various values of n and the air velocity through a drift eliminator stage. The results showed that the pressure drop and drift were strong function of n and air flow rate. In case of CADE and CDE, they were strongly dependent on theta as well. A cellular type packing placed inside the EC was also studied experimentally ans its volume transfer coefficient was correlated in terms of the ratio of liquid to air loading.

36th AIAA Thermophysics Conference, 2003

This work is aimed at developing a numerical model for flow of refrigerant R134a inside adiabatic... more This work is aimed at developing a numerical model for flow of refrigerant R134a inside adiabatic capillary tubes used in small refrigeration systems as expansion devices. Since the flow inside the capillary tube is two-phase with simultaneous existence of vapor and liquid, two ...

All rights reserved by www.ijsrd.com 252 Simulation of PV Module based on Grid Connected Load Sat... more All rights reserved by www.ijsrd.com 252 Simulation of PV Module based on Grid Connected Load Satyapal Singh Uchariya Sanjeev Gupta Student Associate Professor Department of Electrical Engineering Samrat Ashok Technological Institute, Vidisha (M.P) Abstract— In this paper simulation of PV based grid connected system presented in his work. It is based on mathematical modeling which is depend on the different circumstance by different equation like, Isc (Short-Circuit Current(A)), Iph (Photovoltaic Current), Vo (Output voltage) and Is,stc (Diode Saturation Current) etc. It will gives current and voltage of PV module by different number of cells and variation in temperature and irradiation. The PV output voltage boost by the boost converter the AC utility grid by DC/AC inverter control the power. This module further connected to the grid connected system for industrial and commercial application. Solar cell is capable of accurate modeling of I-V and P-V characteristic of a solar module...

This paper presents a flow model that has been developed to design and study the performance of h... more This paper presents a flow model that has been developed to design and study the performance of helical capillary tubes and to mathematically simulate a situation closer to that prevailing in practice. Homogeneous flow of twophase fluid is assumed through the adiabatic capillary tube. The model includes the second law restrictions. The effect variation of different parameters like condenser and evaporator pressures, refrigerant flow rate, degree of subcooling, tube diameter, internal roughness of the tube, pitch and the diameter of the helix on the length of the capillary tube are included in the model. Theoretically predicted lengths of helical capillary tube for R-134a are compared with the length of the capillary tube needed under similar experimental conditions and majority of predictions are found to be within 10% of the experimental value.

The solid-gas contacting for thermal storage and thermal recovery is generally carried out in fix... more The solid-gas contacting for thermal storage and thermal recovery is generally carried out in fixed-bed regenerators. Compared to a fixed bed, higher thermal recovery can be achieved in a moving bed with countercurrent flow of gas and solids. However, the moving beds have ...

In order ot achieve a higher level of performance of a cooling tower, various sub-systems of the ... more In order ot achieve a higher level of performance of a cooling tower, various sub-systems of the tower should be refined and fine tuned to work together as a coherent system. Keeping in veiw the performance of a cooling tower analyses of the various sub-systems namely (a) air inlet system, (b) fill or packing (c) water distribution system (d) drift eliminators and (e) fan and associated equipment are presented here. Energy consumption by the tower sub-systems to the optimal extent only plays a key role in the energy conservation. Experiments with a cellular type of packing gave a fairly small pressure drop. Experiments also carried out with various types of drift eliminators namely cellular type and those made of Wood, Cement Asbestos and Concrete showed minimum pressure drops for the cellular type of drift eliminators. The selection, thus of a right kind packing and drift elimonator with smaller pressure drops (resistance) can result in a substantial energy conservation in the tower.

This paper deals with an experimental study of drift eliminators used in evaporative condensers t... more This paper deals with an experimental study of drift eliminators used in evaporative condensers to determine the pressure drop across them, drift loss and their effects on a refrigeration system performance using an evaporative condenser as one of its components. the experiments were conducted with single and double stages of both wooden drift eliminators (WDE) and concrete drift eliminators (CDE)using both forced and induced draft (ID). The orientation of the drift eliminator plates was varied from 15 degree to 90 degree with horizontal for a single fan speed. Based on the cost analysis for the variation of the pressure drop and the drift loss, an optimum angle of inclination of the drift eliminator plates is suggested. The COP of the refrigeration system increased with increase in fan speed and angle of inclination and decreased with increase in the number of stages. The use of forced draft resulted in better performance of the refrigeration system than with induced draft.

Theoretical work on capillary tube started with homogeneous flow models assuming the effect of sl... more Theoretical work on capillary tube started with homogeneous flow models assuming the effect of slip between the two phases to be negligible as the diameter of such capillary tubes is very small. In the recent years the work on separated flow model considering the slip between the liquid and vapour phases have started picking up. In the present paper an attempt is made to consider the slip between the phases and apply ‘drift flux model’ to simulate the flow of refrigerant through adiabatic capillary tube and compare it with the homogeneous model. The models use well established empirical correlations for friction factor for single phase flow and two phase flow. Comparison of the models with the experimental values available in the literature is made.

The efficient use of power is more important today than ever before. Much attention is paid nowad... more The efficient use of power is more important today than ever before. Much attention is paid nowadays on cooling towers as it is an important resource of energy conservation. Energy conservation is possible only if the tower is designed optimally. In view of optimal design, the authors have developed an expert system for the thermal design of wet cooling towers which is based on logic programming. The present expert system is an intelligent program that contains a large body of knowledge concerning wet cooling towers. The system is able to achieve optimal performance in problem solving and thus help conserve energy.

The objective of the paper is to present a review on the analysis of mechanical-draft wet cooling... more The objective of the paper is to present a review on the analysis of mechanical-draft wet cooling towers. Starting with the basic fundamentals of a cooling tower, an attempt is made here to present an analysis of the important computational models available. The physical situation within a cooling tower is very complex (films and droplets of water in air are in a constantly changing configuration). There is no mathematical model which is capable of simulating every detail of simultaneous heat and mass transfer process occurring within the tower. Consequently, simplifying assumptions must be made for the analysis. A comprehensive list of assumptions is provided which are used for the different models. Eight computational models are analyzed here, namely (a) ESC code, (b) FACTS, (c) VERAZD, (d) STAR, (e) Sutherland's Model, (f) Model by Fujita and Tezuka, (g) Webb's Model, (h) Model by Jaber and Webb. Each model makes use of somewhat different set of assumptions. So, the resul...