Forced Convection Air Cooling of Simulated Low Profile Electronic Components: Part 1—Base Case

1991 ◽  
Vol 113 (1) ◽  
pp. 21-26 ◽  
Author(s):  
G. L. Lehmann ◽  
J. Pembroke
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Flow Rate ◽  
Turbulent Heat Transfer ◽  
Base Case ◽  
Air Cooling ◽  
Turbulent Heat ◽  
Electronic Components ◽  
Channel Spacing ◽  
Low Profile

Forced convection cooling of a simulated array of card-mounted electronic components has been investigated. An important feature of the simulated components is their relatively low profile (height/length = 0.058). Laboratory measurements of heat transfer rates resulting from convective air flow through a low aspect ratio channel are reported. The effect of variations in array position, channel spacing and flow rate is discussed. In the flow range considered laminar, transitional and turbulent heat transfer behavior have been observed. The behavior due to variations in flow rate and channel spacing is well correlated using a Reynolds number based on component length.

Forced Convection Air Cooling of Simulated Low Profile Electronic Components: Part 2—Heat Sink Effects

1991 ◽  
Vol 113 (1) ◽  
pp. 27-32 ◽  
Author(s):  
G. L. Lehmann ◽  
J. Pembroke
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Flow Rate ◽  
Heat Sink ◽  
Heat Sinks ◽  
Air Cooling ◽  
Channel Spacing ◽  
Heat Transfer Behavior ◽  
Low Profile ◽  
Transfer Behavior

Forced convection air cooling of an array of low profile, card-mounted components has been investigated. A simulated array is attached to one wall of a low aspect ratio duct. This is the second half of a two-part study. In this second part the presence of a longitudinally finned heat sink is considered. The heat sink is a thermally passive “flow disturbance”. Laboratory measurements of the heat transfer rates downstream of the heat sink are reported and compared with the measured values which occur when no heat sinks are present. Data are presented for three heat sink geometries subject to variations in channel spacing and flow rate. In the flow range considered laminar, transitional and turbulent heat transfer behavior has been observed. The presence of a heat sink appears to “trip” the start of transition at lower Reynolds numbers than when no heat sinks are present. A Reynolds number based on component length provides a good correlation of the heat transfer behavior due to variations in flow rate and channel spacing. Heat transfer is most strongly effected by flow rate and position relative to the heat sink. Depending on the flow regime (laminar or turbulent) both relative enhancement and reductions in the component Nusselt number have been observed. The impact of introducing a heat sink is greatest for flow rates corresponding to transitional behavior.

scholarly journals Heat Transfer Enhancement of Forced Convection in Horizontal Channel with Heated Block due to Oscillation of Incoming Flow

2018 ◽  
Vol 7 (1) ◽  
Author(s):  
Abdelouahab Bouttout
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Control Volume ◽  
Numerical Procedure ◽  
Horizontal Channel ◽  
Air Cooling ◽  
Electronic Components ◽  
Enhancement Of Heat Transfer ◽  
New Feature ◽  
Volume Method

The study in question consists to amplify the hydrodynamic and thermal instabilities by imposed pulsation during forced convection of air cooling of nine identical heated blocks simulate electronic components mounted on horizontal channel. The finite volume method has been used to solve the governing equations of unsteady forced convection. This approach uses control volume for velocities that are staggered with respect to those for temperature and pressure. The numerical procedure called SIMPLER is used to handle the pressure-velocity coupling. The results show that the time averaged Nusselt number for each heated block depends on the pulsation frequencies and is always larger than in the steady-state case. The new feature in this work is that we obtained a short band of frequencies which the enhancement of heat transfer of all electronic components is greater than 20 % compared with steady non pulsation flow. In addition, the gain in heat transfer Emax attainted the maximum value for the central blocks. Our numerical results were compared with other investigations and found to agree well with experimental data.

Turbulent Heat Transfer in a Revolving Square-Sectioned Tube

1980 ◽  
Vol 22 (2) ◽  
pp. 95-101 ◽  
Author(s):  
W. D. Morris ◽  
F. M. Dias
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Convection Heat Transfer ◽  
Turbulent Heat Transfer ◽  
Electrical Machine ◽  
Turbulent Heat ◽  
Convection Heat ◽  
Forced Convection Heat Transfer ◽  
Parallel Axis ◽  
Correlating Equation

An investigation of turbulent heat transfer in a revolving square-sectioned tube is reported in this paper. It is demonstrated that rotation about a parallel axis enhances the customary forced convection heat transfer, and a correlating equation for assessing this effect is proposed. The range of parameters covered in the experiments permit the results to have application for the assessment of heat transfer in certain gas-cooled electrical machine rotors.

scholarly journals A Study of Rotor Cavities and Heat Transfer in a Cooling Process in a Gas Tubine

1992 ◽  
Author(s):  
R. S. Amano ◽  
V. Pavelic
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Gas Flow ◽  
Numerical Study ◽  
Heat Transfer Process ◽  
High Rate ◽  
Turbulent Heat Transfer ◽  
Air Cooling ◽  
Turbulent Heat ◽  
Accurate Analysis

A high temperature flow through a gas-turbine produces a high rate of turbulent heat transfer between the fluid flow field and the turbine components. The heat transfer process through rotor disks causes thermal stress due to the thermal gradient as well as the centrifugal force causes mechanical stresses; thus an accurate analysis for the evaluation of thermal behavior is needed. This paper presents a numerical study of thermal flow analysis in a two-stage turbine in order to better understand the detailed flow and heat transfer mechanisms through the cavity and the rotating rotor-disks. The numerical computations were performed to predict thermal fields throughout the rotating disks. The method used in this paper is the ‘segregation’ method which requires a much smaller number of grids than actually employed in the computations. The results are presented for temperature distributions through the disk and the velocity fields which illustrate the interaction between the cooling air flow and gas flow created by the disk rotation. The temperature distribution in the disks shows a reasonable trend. The numerical method developed in this study shows that it can be easily adapted for similar computations for air cooling flow patterns through any rotating blade disks in a gas turbine.

A Study of Rotor Cavities and Heat Transfer in a Cooling Process in a Gas Turbine

1994 ◽  
Vol 116 (2) ◽  
pp. 333-338 ◽  
Author(s):  
R. S. Amano ◽  
K. D. Wang ◽  
V. Pavelic
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Gas Flow ◽  
Numerical Study ◽  
Heat Transfer Process ◽  
High Rate ◽  
Turbulent Heat Transfer ◽  
Air Cooling ◽  
Turbulent Heat ◽  
Accurate Analysis

A high-temperature flow through a gas turbine produces a high rate of turbulent heat transfer between the fluid flow field and the turbine components. The heat transfer process through rotor disks causes thermal stress due to the thermal gradient just as the centrifugal force causes mechanical stresses; thus an accurate analysis for the evaluation of thermal behavior is needed. This paper presents a numerical study of thermal flow analysis in a two-stage turbine in order to understand better the detailed flow and heat transfer mechanisms through the cavity and the rotating rotor-disks. The numerical computations were performed to predict thermal fields throughout the rotating disks. The method used in this paper is the “segregation” method, which requires a much smaller number of grids than actually employed in the computations. The results are presented for temperature distributions through the disk and the velocity fields, which illustrate the interaction between the cooling air flow and gas flow created by the disk rotation. The temperature distribution in the disks shows a reasonable trend. The numerical method developed in this study shows that it can be easily adapted for similar computations for air cooling flow patterns through any rotating blade disks in a gas turbine.

Studies of the Deteriorated Turbulent Heat Transfer Regime for the Gas-Cooled Fast Reactor Decay Heat Removal System

2006 ◽  
Author(s):  
Jeong Ik Lee ◽  
Pavel Hejzlar ◽  
Mujid S. Kazimi ◽  
Pradip Saha
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Fast Reactor ◽  
Natural Circulation ◽  
High Surface ◽  
Heat Removal ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Convection Regime ◽  
Decay Heat

Increased reliance on passive emergency cooling using natural circulation of gas at elevated pressure is one of the major goals for the Gas-cooled Fast Reactor (GFR). Since GFR cores have high power density and low thermal inertia, the decay heat removal (DHR) in depressurization accidents is a key challenge. Furthermore, due to its high surface heat flux and low velocities under natural circulation in any post-LOCA scenario, three effects impair the capability of turbulent gas flow to remove heat from the GFR core, namely: (1) Acceleration effect (2) Buoyancy effect (3) Properties variation. This paper reviews previous work on heat transfer mechanisms and flow characteristics of the Deteriorated Turbulent Heat Transfer (DTHT) regime. It is shown that the GFR’s DHR system has a potential for operating in the DTHT regime by performing a simple analysis. A description of the MIT/INL experimental facility designed and built to investigate the DTHT regime is provided together with the first test results. The first runs were performed in the forced convection regime to verify facility operation against well-established forced convection correlations. The results of the three runs at Reynolds numbers 6700, 8000 and 12800 showed good agreement with the Gnielinsky correlation [4], which is considered the best available heat transfer correlation in the forced convection regime and is valid for a large range of Reynolds and Prandtl numbers. However, even in the forced convection regime, the effect of heat transfer properties variation of the fluid was found to be still significant.

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