scholarly journals Heat Transfer by Natural Convection through V-Corrugated Plates

1970 ◽  
Vol 36 ◽  
pp. 1-5
Author(s):  
Mohammad Ali ◽  
M Hasanuzzaman
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Mass Flow Rate ◽  
Heat Transfer Rate ◽  
Flow Rate ◽  
Transfer Rate ◽  
Inlet Temperature ◽  
Cold Plate ◽  
Plate Temperature ◽  
Square Enclosure

An experimental investigation is performed on natural convection heat transfer through a square enclosure of V-corrugated vertical plates. The objective of this investigation is to study the variation of heat transfer rate through the square enclosure with the variation of both hot and cold plate temperatures. Hot plate temperature is varied by heat input. To vary cold plate temperature two parameters are considered: one is mass flow rate of water used to remove heat from cold plate and the other is the inlet temperature of water. Air is the media to transfer heat from the hot V-corrugated plate to cold V-corrugated plate. The result shows that the increase of mass flow rate increases the heat transfer rate and the decrease of water inlet temperature increases the heat transfer rate.Journal of Mechanical Engineering Vol.36 Dec. 2006 pp.1-5DOI = 10.3329/jme.v36i0.804

scholarly journals Effect of Reynolds Number and Property Variation on Fluid Flow and Heat Transfer in the Entrance Region of a Turbine Blade Internal-Cooling Channel

2005 ◽  
Vol 2005 (1) ◽  
pp. 36-44 ◽  
Author(s):  
R. Ben-Mansour ◽  
L. Al-Hadhrami
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Mass Flow Rate ◽  
Heat Transfer Rate ◽  
Turbine Blade ◽  
Flow Rate ◽  
Transfer Rate ◽  
Internal Cooling ◽  
Cooling Channel ◽  
Flow And Heat Transfer

Internal cooling is one of the effective techniques to cool turbine blades from inside. This internal cooling is achieved by pumping a relatively cold fluid through the internal-cooling channels. These channels are fed through short channels placed at the root of the turbine blade, usually called entrance region channels. The entrance region at the root of the turbine blade usually has a different geometry than the internal-cooling channel of the blade. This study investigates numerically the fluid flow and heat transfer in one-pass smooth isothermally heated channel using the RNGk−εmodel. The effect of Reynolds number on the flow and heat transfer characteristics has been studied for two mass flow rate ratios (1/1and1/2) for the same cooling channel. The Reynolds number was varied between10 000and50 000. The study has shown that the cooling channel goes through hydrodynamic and thermal development which necessitates a detailed flow and heat transfer study to evaluate the pressure drop and heat transfer rates. For the case of unbalanced mass flow rate ratio, a maximum difference of8.9% in the heat transfer rate between the top and bottom surfaces occurs atRe=10 000while the total heat transfer rate from both surfaces is the same for the balanced mass flow rate case. The effect of temperature-dependent property variation showed a small change in the heat transfer rates when all properties were allowed to vary with temperature. However, individual effects can be significant such as the effect of density variation, which resulted in as much as9.6% reduction in the heat transfer rate.

scholarly journals Natural convection in a Square Enclosure with Partially Active Vertical Wall

2020 ◽  
Vol 330 ◽  
pp. 01004
Author(s):  
Abdennacer Belazizia ◽  
Smail Benissaad ◽  
Said Abboudi
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Vertical Wall ◽  
Left Wall ◽  
Convection And Heat Transfer ◽  
Square Enclosure ◽  
Active Location

Steady, laminar, natural convection flow in a square enclosure with partially active vertical wall is considered. The enclosure is filled with air and subjected to horizontal temperature gradient. Finite volume method is used to solve the dimensionless governing equations. The physical problem depends on three parameters: Rayleigh number (Ra =103-106), Prandtl number (Pr=0.71), and the aspect ratio of the enclosure (A=1). The active location takes two positions in the left wall: top (T) and middle (M). The main focus of the study is on examining the effect of Rayleigh number on fluid flow and heat transfer rate. The results including the streamlines, isotherm patterns, flow velocity and the average Nusselt number for different values of Ra. The obtained results show that the increase of Ra leads to enhance heat transfer rate. The fluid particles move with greater velocity for higher thermal Rayleigh number. Also by moving the active location from the top to the middle on the left vertical wall, convection and heat transfer rate are more important in case (M). Furthermore for high Rayleigh number (Ra=106), Convection mechanism in (T) case is principally in the top of the enclosure, whereas in the remaining case it covers the entire enclosure.

Numerical Studies on Natural Convection Heat Transfer – Fins with Closed Top

2014 ◽  
Vol 592-594 ◽  
pp. 1682-1686 ◽  
Author(s):  
C. Balachandar ◽  
S. Arunkumar ◽  
M. Venkatesan
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Convection Heat Transfer ◽  
Base Plate ◽  
Plate Temperature ◽  
Ansys Fluent ◽  
Numerical Studies ◽  
Vertical Base

Fins are extended surfaces provided to enhance the heat transfer rate of a system. Several attempts have been made in the past to augment the heat transfer rate by using fins of various geometries. In the present study an array of rectangular fins with closed top, standing on a vertical base is analysed under natural convection conditions using commercial CFD code ANSYS FLUENT©. The numerical model is validated with the available experimental results for fins with open top under natural convection conditions. The plate fin heat sink is analysed for a constant heat duty of 60 W. The height, thickness and length of the fins are taken to be constant throughout the analysis. A detailed study is carried out to examine the dependency of the base plate temperature on the thickness of the closed top and on the number of fins. It is concluded based on the analysis that heat fins with closed top are found to have a decreased base plate temperature compared to the conventional rectangular fins.

scholarly journals Natural Convection in a Differentially Heated Square Enclosure with a Solid Polygon

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
R. Roslan ◽  
H. Saleh ◽  
I. Hashim
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Critical Size ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
Thermal Conductivity Ratio ◽  
Left Wall ◽  
Square Enclosure

The aim of the present numerical study is to analyze the conjugate natural convection heat transfer in a differentially heated square enclosure containing a conductive polygon object. The left wall is heated and the right wall is cooled, while the horizontal walls are kept adiabatic. The COMSOL Multiphysics software is applied to solve the dimensionless governing equations. The governing parameters considered are the polygon type,3≤N≤∞, the horizontal position,0.25≤X0≤0.75, the polygon size,0≤A≤π/16, the thermal conductivity ratio,0.1≤Kr≤10.0, and the Rayleigh number,103≤Ra≤106. The critical size of the solid polygon was found exists at low conductivities. The heat transfer rate increases with the increase of the size of the solid polygon, until it reaches its maximum value. Here, the size of the solid polygon is reaches its critical value. Further, beyond this critical size of the solid polygon, will decrease the heat transfer rate.

scholarly journals A Study on the Heat Transfer Rate Performance of the Hot Water Circulating in the Tubes in the Hot Water Panels Laid in the Walls and Floor of a Small Leisure Cabin in Relation to Changes in the Temperature and Flow Rate of the Hot Water

2021 ◽  
Vol 58 (1) ◽  
pp. 3468-3476
Author(s):  
Dong-Hyun Cho
Keyword(s):  
Heat Transfer ◽  
Mass Flow Rate ◽  
Heat Transfer Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Energy ◽  
Transfer Rate ◽  
Hot Water ◽  
Radiant Heat Transfer ◽  
Rate Performance

In this study, hot water panels were laid in the three walls as well as the floor of a small leisure cabin to implement radiant heating with the heat supplied by the hot water circulating inside the hot water tubes in the hot water panels. As a result of the study as such, compared to the forced convection heating at the current technology level in which air is forced to circulate by the air conditioner, the radiant heat transfer by the hot water panels laid in the floor and walls of the small leisure cabin in this study implemented more comfortable heating and wellbeing heating beneficial to health because it implemented heating without any movement or circulation of air. In addition, this study investigated heater accessories suitable for small leisure cabins not larger than 6 m2 to significantly reduce thermal energy and manufacturing costs. The thermal energy lost by hot water per unit time and the thermal energy obtained by air inside the small leisure cabin per unit time coincided well at the accuracy of ±5%. Therefore, the reliability of the result of the heat transfer rate accuracy experiment in this study was secured. As the mass flow rate of the hot water increased, the heat transfer rate performance of the small leisure cabin improved. In addition, as the mass flow rate of hot water increased, the heat transfer rate performance of the small leisure cabin improved linearly.

Natural Convection in a Vertical Microchannel

2005 ◽  
Vol 127 (9) ◽  
pp. 1053-1056 ◽  
Author(s):  
Cha’o-Kuang Chen ◽  
Huei Chu Weng
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Transfer Rate ◽  
Flow Rate ◽  
Transfer Rate ◽  
Temperature Jump ◽  
Volume Flow Rate ◽  
Slip Flow ◽  
Velocity Slip ◽  
Volume Flow

It is highly desirable to understand the fluid flow and the heat transfer characteristics of buoyancy-induced micropump and microheat exchanger in microfluidic and thermal systems. In this study, we analytically investigate the fully developed natural convection in an open-ended vertical parallel-plate microchannel with asymmetric wall temperature distributions. Both of the velocity slip and the temperature jump conditions are considered because they have countereffects both on the volume flow rate and the heat transfer rate. Results reveal that in most of the natural convection situations, the volume flow rate at microscale is higher than that at macroscale, while the heat transfer rate is lower. It is, therefore, concluded that the temperature jump condition induced by the effects of rarefaction and fluid-wall interaction plays an important role in slip-flow natural convection.

Condensation Heat Transfer With High Partial Pressure Non Condensable Gas Inside Tube

2009 ◽  
Author(s):  
Jun Xia Zhang ◽  
Li Wang ◽  
Hong Ying Li ◽  
Ping Wu
Keyword(s):  
Heat Transfer ◽  
Partial Pressure ◽  
Heat Transfer Rate ◽  
Flow Rate ◽  
Transfer Rate ◽  
Cooling Water ◽  
Condensation Heat Transfer ◽  
Inlet Temperature ◽  
Separate Type ◽  
High Partial Pressure

An experimental study on the condensation heat transfer in a non-vacuum separate type heat tube is carried out to comprehend the effect of high partial pressure NC condensable gas on the condensation heat transfer of vapor. The outer wall temperature along the tube length and the condensation heat transfer rate at different operation parameters, including inlet pressure and temperature of vapor, inlet temperature of cooling water and flow rate of cooling water, were measured. The factors influencing the condensation heat transfer coefficient (HTC) and condensation heat transfer rate were analyzed. The results show that the non-vacuum separate type heat pipe can run steadily; the region of the stagnant high partial pressure NC gas in the condenser tube is caused by the pressing of both vapor from the inlet and the condensation liquid at the rear of the tube; vapor flow rate and vapor inlet pressure have prominent influence on the condensation heat transfer rate and condensation HTC, and inlet temperature of cooling water affects the condensation HTC slightly.

scholarly journals CFD Analysis of Turbulent Heat Transfer Characteristics in Cubical Enclosure

2019 ◽  
Vol 9 (1) ◽  
pp. 6116-6120
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
Turbulent Flow ◽  
Mass Flow Rate ◽  
Heat Transfer Rate ◽  
Flow Rate ◽  
Transfer Rate ◽  
Flow Behavior ◽  
Cubical Enclosure ◽  
Flow Case

In this paper we present the turbulent flow and convective heat transfer phenomena inside a cubical enclosure with an internal heat source. The enclosure is designed with an inlet and outlet vent and the heat source is mounted on the bottom wall. The turbulent flow is modeled by the computational fluid dynamics (CFD) approach using Lambremhorst k- ε turbulence model. A finite difference method is used to discretize the governing equations and an in- house CFD used is developed for simulating the turbulent characteristics . The parametric study is performed for the assisting and opposing flow character stics inside the enclosure by varying the Grashof (Gr) and Reynolds (Re) number in the range of 105 ≤ Gr ≤ 1010 and 102 ≤ Re ≤ 106. The present study emphasises that the inertial force and buoyancy force has significant impact on the recirculation flow p attern inside the enclosure . The heat transfer rate is drastically influenced by the assisting and opppsing flow behavior developed inside the enclosure. It is observed that the mass flow rate across the outlet vent increases linearly with the Reynolds nu mber. The flow behavior is highly chaotic with the development of instabilities inside the enclosure . The streamlines and temperature distribution patterns inside the enclosure indicated that the assisting flow enhanced the heat transfer rate by 48% while the opposing flow suppressed the heat transfer rate by 45% inside the enclosure. A multi recirculating convective cell pattern is formed at higher Grashof number and the size of the cell increases with increase in Grashof number . It is also found that the mass flow rate across the outlet vent increases linearly for assisting flow case while it decreases for the opposing flow case. It is evident from the present study that the assisting flow case is best suited for heat transfer enchancement in cubical enclosure.

Effect of magnetic field-dependent thermal conductivity on natural convection of magnetic nanofluid inside a square enclosure

2019 ◽  
Vol 29 (4) ◽  
pp. 1466-1489 ◽  
Author(s):  
Mohammadhossein Hajiyan ◽  
Shohel Mahmud ◽  
Mohammad Biglarbegian ◽  
Hussein A. Abdullah ◽  
A. Chamkha
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Hartmann Number ◽  
Magnetic Nanofluid ◽  
Content Type ◽  
Square Enclosure ◽  
Field Dependent

Purpose The purpose of this paper is to investigate the convective heat transfer of magnetic nanofluid (MNF) inside a square enclosure under uniform magnetic fields considering nonlinearity of magnetic field-dependent thermal conductivity. Design/methodology/approach The properties of the MNF (Fe3O4+kerosene) were described by polynomial functions of magnetic field-dependent thermal conductivity. The effect of the transverse magnetic field (0 < H < 105), Hartmann Number (0 < Ha < 60), Rayleigh number (10 <Ra <105) and the solid volume fraction (0 < φ < 4.7%) on the heat transfer performance inside the enclosed space was examined. Continuity, momentum and energy equations were solved using the finite element method. Findings The results show that the Nusselt number increases when the Rayleigh number increases. In contrast, the convective heat transfer rate decreases when the Hartmann number increases due to the strong magnetic field which suppresses the buoyancy force. Also, a significant improvement in the heat transfer rate is observed when the magnetic field is applied and φ = 4.7% (I = 11.90%, I = 16.73%, I = 10.07% and I = 12.70%). Research limitations/implications The present numerical study was carried out for a steady, laminar and two-dimensional flow inside the square enclosure. Also, properties of the MNF are assumed to be constant (except thermal conductivity) under magnetic field. Practical implications The results can be used in thermal storage and cooling of electronic devices such as lithium-ion batteries during charging and discharging processes. Originality/value The accuracy of results and heat transfer enhancement having magnetic field-field-dependent thermal conductivity are noticeable. The results can be used for different applications to improve the heat transfer rate and enhance the efficiency of a system.

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