scholarly journals Numerical study of melting and heat transfer of PCM in a rectangular cavity with bilateral flow boundary conditions

2021 ◽  
pp. 101183
Author(s):  
Haofeng Qin ◽  
Ziyun Wang ◽  
Wenlei Heng ◽  
Zhen Liu ◽  
Peiyi Li
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Numerical Study ◽  
Rectangular Cavity ◽  
Flow Boundary

Natural Convection in an Inclined Rectangular Cavity With Different Thermal Boundary Conditions at the Top Plate

1988 ◽  
Vol 110 (2) ◽  
pp. 350-357 ◽  
Author(s):  
T. G. Karayiannis ◽  
J. D. Tarasuk
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Boundary Conditions ◽  
Forced Convection ◽  
Rectangular Cavity ◽  
Forced Flow ◽  
Cold Plate ◽  
Transfer Rates ◽  
Average Heat ◽  
Thermal Boundary Conditions

Natural convection inside a rectangular cavity with different temperature boundary conditions on the cold top plate was studied using a Mach-Zehnder interferometer for θ = 15, 45, and 60 deg to the horizontal. At θ = 60 deg coupling with external forced convection and non-coupled heat transfer from a cavity with an isothermal top plate was studied. In all experiments the bottom hot plate was isothermal. The Rayleigh number Ra was varied from subcritical to 6×105 and the cavity aspect ratio ARx, from 6.68 to 33.4. The Reynolds number of the external forced flow Redh was constant and approximately equal to 5.8×104. It was found that for Ra ≲ 3×104 the differing thermal boundary conditions at the top plate did not affect the local or average heat transfer rates from the cavity. For Ra ≳ 3×104 coupling at the top plate compared to the non-coupled case resulted not only in a reduction in the variation of the local heat transfer rates at the cold plate, but also in a significant reduction in the variation of the average transfer rates from hot and cold plates of the cavity. Forced convection at the top plate as compared to natural convection resulted only in a small reduction in the heat transfer coefficient at the cold plate. Correlation equations for coupled and noncoupled average heat transfer rates are presented.

Influence of Non Uniform Boundary Conditions on Laminar Free Convection in Wavy Square Cavity With Partial Partitions

Volume 1 ◽  
2004 ◽  
Author(s):  
A. Sabeur-Bendehina ◽  
M. Aounallah ◽  
L. Adjlout ◽  
O. Imine ◽  
B. Imine
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Numerical Study ◽  
Laminar Regime ◽  
Uniform Temperature ◽  
Square Cavity ◽  
Vertical Walls ◽  
The Mean ◽  
Rayleigh Numbers ◽  
Partial Partitions

In the present work, a numerical study of the effect of non uniform boundary conditions on the heat transfer by natural convection in cavities with partial partitions is investigated for the laminar regime. This problem is solved by using the partial differential equations which are the equation of mass, momentum and energy. The tests were performed for different boundary conditions and different Rayleigh numbers while the Prandtl number was kept constant. Four geometrical configurations were considered namely three and five undulations with increasing and decreasing partition length. The results obtained show that the non uniform temperature in the vertical walls affects the flow and the heat transfer. The mean Nusselt number decreases comparing with the heat transfer in the undulated square cavity without partitions for all non uniform boundary conditions tested.

Natural convection in a rectangular cavity filled with nanofluids

2018 ◽  
Vol 28 (6) ◽  
pp. 1410-1432 ◽  
Author(s):  
Cornelia Revnic ◽  
Eiyad Abu-Nada ◽  
Teodor Grosan ◽  
Ioan Pop
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Design Methodology ◽  
Volume Fraction ◽  
Numerical Study ◽  
Rectangular Cavity ◽  
Heat Transfer Characteristics ◽  
Content Type ◽  
Flow And Heat Transfer ◽  
Comprehensive Survey

Purpose This paper aims to develop a numerical study of the steady natural convection in a rectangular cavity filled with the CuO–water-based nanofluid. It is assumed that the viscosity of nanofluids depends on the temperature and on the nanofluids volume fraction. Design/methodology/approach The mathematical nanofluid model has been formulated on the basis of the model proposed by Buongiorno (2006). The system of partial differential equations is written in terms of a dimensionless stream function, vorticity, temperature and the volume fraction of the nanoparticles, and is solved numerically using the finite difference method for different values of the governing parameters. Findings It is found that both fluid flow and heat transfer coefficient are affected by the considered parameters. Thus, the Nusselt number is slowly increasing with increasing volume fraction from 2 per cent to 5 per cent and it is more pronounced increasing with increasing Rayleigh number from 103 to 105. Originality/value Buongiorno’s (2006) nanofluid model has been applied for the flow with the characteristics as mentioned in the paper. A comprehensive survey on the behavior of flow and heat transfer characteristics has been presented. All plots presented in the paper are new and are not reported in any other study.

Simulation of Micro-Scale Jet Impingement Heat Transfer

2000 ◽  
Author(s):  
Paul A. Boeschoten ◽  
Deborah V. Pence ◽  
James A. Liburdy
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Mach Number ◽  
Boundary Conditions ◽  
Slip Velocity ◽  
Slip Flow ◽  
Local Maximum ◽  
Jet Impingement ◽  
Micro Scale ◽  
Flow Boundary

Abstract The heat transfer performance of a micro-scale, axisymmetric, confined jet impinging on a flat surface at high Mach numbers (0.2 to 0.6) and low Reynolds numbers (419 to 1310) was computationally studied. The flow is characterized by Knudsen numbers, based on the jet radius, large enough (0.0013) to warrant slip-flow boundary conditions at the impinging surface. The effects of Mach number, compressibility, and slip-flow on heat transfer results are presented, along with the local Nusselt number distributions, and velocity and temperature fields near the impingement surface. Results for uniform wall heat flux show that the wall temperature decreases with increasing Mach number, with a local minimum at r/D = 0.7. The slip velocity also increases with Mach number with peak values also near r/D = 0.7. The resulting Nusselt number increases with increasing Mach number, and a local maximum in the Nusselt number is observed at r/D = 0.6, not at the centerline. In general, compressibility improves heat transfer due to increased fluid density near the impinging surface. Also, inclusion of slip-velocity increases the rate of heat transfer. However, the accompanying temperature-jump condition at the wall is found to reduce the local heat transfer rate. The net effect of the slip-flow boundary conditions applied in this study was an overall reduction in heat transfer.

Numerical study of heat transport in thermally isolated flow-rate microsensors

1992 ◽  
Vol 70 (10-11) ◽  
pp. 904-907
Author(s):  
N. Swart ◽  
A. Nathan
Keyword(s):  
Heat Transfer ◽  
Heat Flow ◽  
Boundary Conditions ◽  
Heat Transport ◽  
Flow Rate ◽  
Energy Equation ◽  
Numerical Study ◽  
Control Volume ◽  
Circuit Simulator ◽  
Temperature Distributions

The temperature distributions in thermally isolated cantilever based flow-rate microsensors have been numerically calculated for different gas temperatures and gas velocities. In particular, we investigate the efficiency of heat transfer to the flowing gas and corresponding directions of heat flow in the system. The above analysis is based on a solution to the energy equation under appropriate boundary conditions. The equation was discretized using a control volume procedure, based on which an equivalent circuit was devised and subsequently simulated using a circuit simulator such as SPICE.

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