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Yadav A.S.,Technocrats Institute of Technology Excellence
Journal of the Chinese Institute of Engineers, Transactions of the Chinese Institute of Engineers,Series A/Chung-kuo Kung Ch'eng Hsuch K'an | Year: 2015

Solar air heaters are cheap and extensively used solar energy collection devices for space heating, seasoning of timber, curing of industrial products and can also be effectively used for curing/drying of concrete/clay building components and in air-conditioning systems. In this article, the effect of relative roughness height on Nusselt number and friction factor in an artificially roughened solar air heater having circular-sectioned transverse rib roughness (duct aspect ratio, AR = 5:1) is studied by adopting CFD (computational fluid dynamics) approach. Numerical solutions are obtained using commercial CFD software ANSYS FLUENT v12.1. Computations based on the finite volume method with the SIMPLE algorithm have been conducted. Circular-sectioned transverse ribs are applied at the underside of the top of the duct, that is, on the absorber plate. The rib pitch (P) and rib height (e) are varied by keeping rib-pitch-to-rib-height ratio constant (P/e = 14.29). The rib-height-to-hydraulic-diameter ratio (e/D) studied is 0.021, 0.03, 0.042, and 0.06. For each rib-height-to-hydraulic-diameter ratio (e/D), simulations are executed at six Reynolds numbers from 3800 to 18,000 (relevant in solar air heater). The thermal enhancement factor for e/D = 0.042 is found to be the best for the investigated range of parameters and is about 1.635. © 2015 The Chinese Institute of Engineers.


Yadav A.S.,Technocrats Institute of Technology Excellence | Yadav A.S.,Maulana Azad National Institute of Technology | Bhagoria J.L.,Maulana Azad National Institute of Technology
International Journal of Heat and Mass Transfer | Year: 2014

In this article, a numerical investigation is conducted to analyze the two-dimensional incompressible Navier-Stokes flows through the artificially roughened solar air heater for relevant Reynolds number ranges from 3800 to 18,000. Twelve different configurations of equilateral triangular sectioned rib (P/e = 7.14-35.71 and e/d = 0.021-0.042) have been used as roughness element. The governing equations are solved with a finite-volume-based numerical method. The commercial finite-volume based CFD code ANSYS FLUENT is used to simulate turbulent airflow through artificially roughened solar air heater. The RNG k-ε turbulence model is used to solve the transport equations for turbulent flow energy and dissipation rate. A total numbers of 432,187 quad grid intervals with a near wall elements spacing of y+ ≈ 2 are used. Detailed results about average heat transfer and fluid friction in an artificially roughened solar air heater are presented and discussed. The effects of grid distributions on the numerical predictions are also discussed. It has been observed that for a given constant value of heat flux (1000 W/m 2), the performance of the artificially roughened solar air heater is strong function of the Reynolds number, relative roughness pitch and relative roughness height. Optimum configuration of the roughness element for artificially roughened solar air heater is evaluated. © 2013 Elsevier Ltd. All rights reserved.


Yadav A.S.,Technocrats Institute of Technology Excellence | Yadav A.S.,Maulana Azad National Institute of Technology | Bhagoria J.L.,Maulana Azad National Institute of Technology
The Scientific World Journal | Year: 2013

Solar air heater is a type of heat exchanger which transforms solar radiation into heat energy. The thermal performance of conventional solar air heater has been found to be poor because of the low convective heat transfer coefficient from the absorber plate to the air. Use of artificial roughness on a surface is an effective technique to enhance the rate of heat transfer. A CFD-based investigation of turbulent flow through a solar air heater roughened with square-sectioned transverse rib roughness has been performed. Three different values of rib-pitch (P) and rib-height (e) have been taken such that the relative roughness pitch (P / e = 14.29) remains constant. The relative roughness height, e / D, varies from 0.021 to 0.06, and the Reynolds number, Re, varies from 3800 to 18,000. The results predicted by CFD show that the average heat transfer, average flow friction, and thermohydraulic performance parameter are strongly dependent on the relative roughness height. A maximum value of thermohydraulic performance parameter has been found to be 1.8 for the range of parameters investigated. Comparisons with previously published work have been performed and found to be in excellent agreement. © 2013 Anil Singh Yadav and J. L. Bhagoria.


Ahirwal V.,Technocrats Institute of Technology | Agrawal J.,Technocrats Institute of Technology Excellence
IEEE International Conference on Computer Communication and Control, IC4 2015 | Year: 2015

There was different type analysis work already proposed in the past for the enhancement of gray scale images these are corrupted by salt and pepper noise, however in case of color image denoising for color impulse noise need more effort during this field. This research object to epitomize a powerful approach for the removal as well as enhancement of color and gray level images those are extremely corrupted color impulse noise also on gray scale impulse noise. In color impulse noise images are corrupted by the pixel value black and white are making certain that red, green, blue, black and white dot within the image. In proposing algorithm take a color noise image separated into 3 subparts, i.e. red, green and blue color pixel matrices, then these 3 matrices are checked for noisy or noisy free pixels. Then choose 3×3 size window of every frame with targeted pixel value check if its value is zeros or two fifty five then the image is corrupted otherwise noise free image. If the image is noisy and target pixels neighboring pixel value is between 0's and 255's currently we interchange values of the corrupted pixel by unsymmetrical trimmed median and if target pixels neighboring pixel value is 0's or 255's now we interchange the value of pixels by the unsymmetrical trimmed average. The proposed filter algorithm shows higher simulation results as compared the existing algorithms. The simulation result shows efficient performance in expressions of peak signal to noise ratio (PSNR) and mean square error (MSE) and complexity additionally shows higher end up in terms of human and computer vision. © 2015 IEEE.


Yadav A.S.,Maulana Azad National Institute of Technology | Yadav A.S.,Technocrats Institute of Technology Excellence | Bhagoria J.L.,Maulana Azad National Institute of Technology
Numerical Heat Transfer; Part A: Applications | Year: 2014

A numerical investigation of turbulent flows through a solar air heater roughened with semicircular sectioned transverse rib roughness has been executed. The physical problem is represented mathematically by a set of governing equations, and the transport equations are solved using the finite element method. The numerical results show that the flow-field, average Nusselt number, and average friction factor are strongly dependent on the relative roughness height. The thermohydraulic performance parameter is found to be the maximum for the relative roughness height of 0.042. Comparisons with previously published work are performed and were found to be in excellent agreement. © 2014 Taylor and Francis Group, LLC.

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