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Search Results: 1 - 10 of 3523 matches for " Rectangular channel "
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Convection in a rectangular channel with a flow of water in laminar-turbulent transition with high heat fluxes
Silin,N.; Masson,V.; García,J. C.;
Latin American applied research , 2010,
Abstract: in this work we examine the phenomenon of laminar-turbulent transition in a heated rectangular channel under high heat fluxes and water as a working fluid. we use an experimental device that allows the electric heating of the walls and the measurement of its temperature through thermocouples housed beneath the surface. the results of this initial exploration clearly show the dependence of the convection coefficient on the heat flux through different mechanisms. in first place we can see an increase in the convection coefficient with the heat flux that is correctly predicted for laminar and turbulent flows by the sieder-tate correction. in second place, there was a clear change of behaviour that corresponds to the start of the transition to turbulence. the reynolds number that corresponds to the departure from laminar behavior was independent of the heat flux in the walls within the conditions covered in this study.
Ketidakstabilan Aliran Sekunder pada Saluran Lengkung Berpenampang Persegi
Nursubyakto .
Jurnal Teknik Mesin , 2010,
Abstract: Secondary flow is the counter rotating vortex that appears in the channel when a fluid flows in a curved channel. The occurence of this secondary flow is caused by imbalance between centrifugal force and pressure on the outer wall of the channel. When Dean number is increased the additional secondary flow appears to the main secondary flow and/or disappears. This paper investigated the occurence of the additional secondary flow to the main flow with rectangular cross section and the radius of curvature varied from 1 to 10. The result shows that increament of curvature ratio the additional Dean voritces appears and beyond of ratio of 4 is constant. The effect of the additional secondary flow to the friction factor is also predicted.
REVIEW OF HEAT TRANSFER ENHANCEMENT IN DIFFERENT TYPES OF BAFFLES AND THEIR ORIENTATIONS.
S.P.WALDE,V.M.KRIPLANI
International Journal of Engineering Science and Technology , 2012,
Abstract: The use of baffles in channel is commonly used for passive heat transfer enhancement strategy in single phase internal flow. Considering the rapid increase in energy demand, effective heat transfer enhancement techniques have become important task worldwide. Some of the applications of passive heat transfer enhancement strategies are in process industries, thermal regenerator, Shell and tube type heat exchanger, Internal cooling system of gas turbine blades, radiators for space vehicles and automobiles, etc. Thepresent paper is a review of different types of baffles and its arrangement. According to recent studies these are known to be economic heat transfer augmentation tools.
Convection in a rectangular channel with a flow of water in laminar-turbulent transition with high heat fluxes
N. Silin,V. Masson,J. C. García
Latin American applied research , 2010,
Abstract: In this work we examine the phenomenon of laminar-turbulent transition in a heated rectangular channel under high heat fluxes and water as a working fluid. We use an experimental device that allows the electric heating of the walls and the measurement of its temperature through thermocouples housed beneath the surface. The results of this initial exploration clearly show the dependence of the convection coefficient on the heat flux through different mechanisms. In first place we can see an increase in the convection coefficient with the heat flux that is correctly predicted for laminar and turbulent flows by the Sieder-Tate correction. In second place, there was a clear change of behaviour that corresponds to the start of the transition to turbulence. The Reynolds number that corresponds to the departure from laminar behavior was independent of the heat flux in the walls within the conditions covered in this study.
Pressure drop coefficients for elliptic and circular sections in one, two and three-row arrangements of plate fin and tube heat exchangers
Bordalo, Sérgio Nascimento;Saboya, Francisco Eduardo Mour?o;
Journal of the Brazilian Society of Mechanical Sciences , 1999, DOI: 10.1590/S0100-73861999000400004
Abstract: the objective of the present work is the experimental determination of pressure drop coefficients (loss coefficients) for elliptic and circular sections in one, two and three-row arrangements of plate fin and tube heat exchangers. the experiments permitted to correlate the dimensionless loss coefficient with the flow reynolds number in the rectangular channel formed by the plate fins. the experimental technique consisted of the measurement of the longitudinal pressure distribution along the flow channel, for several values of air mass flow rate. the total number of data runs, each one characterized by the flow reynolds number, was 216. the present geometry is used in compact heat exchangers for air conditioning systems, heaters, radiators, and others. also, it is verified the influence of the utilization of elliptic tubes, instead of circular ones, in the pressure drop. the measurements were performed for reynolds numbers ranging from 200 to 1900.
Experimental investigation of operating parameters and control the performance of a PEM fuel cell
I. Khazaee, M. Ghazikhani
International Journal of Energy and Environment , 2012,
Abstract: In this study, the performance of a PEM fuel cell is investigated experimentally. Some parameters such as input oxygen temperature, input hydrogen temperature, cell temperature, input pressure, oxygen flow rate and hydrogen flow rate affect the performance of the cell. A series of experiments are carried out to investigate the influence of the above parameters on the polarization curve under the normal conditions. A PEM fuel cell with 25 cm2 active area and Nafion 117 membrane for the anode and cathode is employed as a membrane electrode assembly. The results show that increase in the operating temperature of the cell and inlet gases and pressure can enhance the cell performance. Also the results show that when the oxygen flow rate is at 0.9 L/min and the hydrogen flow rate is at 0.5 L/min the performance of the cell increases.
Pressure drop coefficients for elliptic and circular sections in one, two and three-row arrangements of plate fin and tube heat exchangers
Bordalo Sérgio Nascimento,Saboya Francisco Eduardo Mour?o
Journal of the Brazilian Society of Mechanical Sciences , 1999,
Abstract: The objective of the present work is the experimental determination of pressure drop coefficients (loss coefficients) for elliptic and circular sections in one, two and three-row arrangements of plate fin and tube heat exchangers. The experiments permitted to correlate the dimensionless loss coefficient with the flow Reynolds number in the rectangular channel formed by the plate fins. The experimental technique consisted of the measurement of the longitudinal pressure distribution along the flow channel, for several values of air mass flow rate. The total number of data runs, each one characterized by the flow Reynolds number, was 216. The present geometry is used in compact heat exchangers for air conditioning systems, heaters, radiators, and others. Also, it is verified the influence of the utilization of elliptic tubes, instead of circular ones, in the pressure drop. The measurements were performed for Reynolds numbers ranging from 200 to 1900.
Laboratory Study on Transverse Mixing Coefficient of Rivers
河流横向混合系数的室内试验

Mu Jinbo,Hou Kefu,
慕金波
,侯克复

环境科学 , 1991,
Abstract: The formulary structure about transverse mixing coefficient of rivers has been studied at the laboratory model of straight rectangular open channel. In the model, a lot of trace experiments were performed so that 63 groups of data were obtained. On the basis of the experiments, the relation for transverse mixing coefficient was offered and analyzed. The empirical formulation and some conclusions induced by the model will provide reference for ascertainment of the transverse mixing coefficient in natural streams.
Numerical Simulation of Asymmetric Merging Flow in a Rectangular Channel  [PDF]
Abuzar Abid Siddiqui
World Journal of Mechanics (WJM) , 2016, DOI: 10.4236/wjm.2016.64010
Abstract: The steady, asymmetric and two-dimensional flow of viscous, incompressible and Newtonian fluid through a rectangular channel with splitter plate parallel to walls is investigated numerically. Earlier, the position of the splitter plate was taken as a centreline of channel but here it is considered its different positions which cause the asymmetric behaviour of the flow field. The geometric parameter that controls the position of splitter is defined as splitter position parameter a. The plane Poiseuille flow is considered far from upstream and downstream of the splitter. This flow-problem is solved numerically by a numerical scheme comprising a fourth order method, followed by a special finite-method. This numerical scheme transforms the governing equations to system of finite-difference equations, which are solved by point S.O.R. iterative method. In addition, the results obtained are further refined and upgraded by Richardson Extrapolation method. The calculations are carried out for the ranges -1 < α < 1, and 0 ≤ R < 105. The results are compared with existing literature regarding the symmetric case (when a = 0) for velocity, vorticity and skin friction distributions. The comparison is very favourable. Moreover, the notable thing is that the decay of vorticity to its downstream value takes place over an increasingly longer scale of x as R increases for symmetric case but it is not so for asymmetric one.
A COMPARATIVE STUDY WITH FLOW VISUALIZATION OF TURBULENT FLUID FLOW IN AN ELBOW
RABIN DEBNATH,,SOMNATH BHATTACHARJEE,ARINDAM MANDAL,DEBASISH ROY
International Journal of Engineering Science and Technology , 2010,
Abstract: The analysis of the turbulent fluid flow in an elbow is important for a wide range of engineering applications like heat exchangers, particle transport piping system, air conditioning devices, pneumatic conveying system etc. Elbow is an important component of pneumatic conveying system and the flow structure within it plays an important role to covey materials. In this paper, a comparative study has been made between three types of turbulent models e.g. standard
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