Experiments on Free Convection Between Vertical Plates With Symmetric Heating

1982 ◽  
Vol 104 (3) ◽  
pp. 501-507 ◽  
Author(s):  
R. A. Wirtz ◽  
R. J. Stutzman
Keyword(s):  
Heat Flux ◽  
Temperature Field ◽  
Laboratory Experiments ◽  
Heat Fluxes ◽  
Maximum Temperature ◽  
Parallel Plates ◽  
Flow Data ◽  
Symmetric Heating ◽  
Reported Data ◽  
Plate Geometry

Laboratory experiments on natural convection of air between vertical parallel plates with uniform and symmetric heat fluxes are reported. Data collection was through direct temperature measurement using thermocouples and through analysis of interferograms of the flow. Data were collected over a range of heat fluxes and geometric parameters where the flow was in the developing temperature field regime. A correlation is developed that allows for the calculation of the maximum temperature variation of the plates for a given input heat flux and plate geometry. The equation is expected to be accurate to ±5 percent.

The Temperature Distribution Within a Sphere Placed in a Directed Uniform Heat Flux and Allowed to Radiatively Cool

1985 ◽  
Vol 107 (1) ◽  
pp. 28-32 ◽  
Author(s):  
D. Duffy
Keyword(s):  
Heat Flux ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Analytic Solution ◽  
Blackbody Radiation ◽  
Heat Fluxes ◽  
Uniform Heat Flux ◽  
Transform Methods ◽  
Uniform Heat ◽  
Large Heat

The temperature field within a sphere is found when the sphere is heated by a directed heat flux and cooled by blackbody radiation. For small heat fluxes, the analytic solution is obtained by transform methods. For large heat fluxes, the solution is computed numerically.

scholarly journals A Theorem for Finding Maximum Temperature in Wet Grinding

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
J. L. González-Santander ◽  
G. Martín
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Temperature Field ◽  
Integral Form ◽  
Stationary Regime ◽  
Time Dependent ◽  
Maximum Temperature ◽  
Theoretical Computation ◽  
Constant Heat ◽  
Workpiece Surface

We consider the solutions found in the literature for heat transfer in surface grinding, assuming a constant heat transfer coefficient for the coolant acting on the workpiece surface and a constant or linear heat flux profiles entering into the workpiece. From the integral form of the time-dependent temperature field reached in the workpiece, assuming the previous conditions, we prove that the maximum temperature always occurs in the stationary regime on the workpiece surface within the contact zone between the wheel and the workpiece. This result assures a very rapid method for the theoretical computation of the maximum temperature.

Inverse Design of Cooling of Electronic Chips Subject to Specified Hot Spot Temperature and Coolant Inlet Temperature

2015 ◽  
Author(s):  
Sohail R. Reddy ◽  
George S. Dulikravich
Keyword(s):  
Heat Flux ◽  
Hot Spot ◽  
Heat Fluxes ◽  
Operating Conditions ◽  
Heat Transfer Analysis ◽  
Maximum Temperature ◽  
Fluid Temperature ◽  
Cooling Fluid ◽  
Pin Fin ◽  
The Given

Most methods for designing electronics cooling schemes do not offer the information on what levels of heat fluxes are maximally possible to achieve with the given material, boundary and operating conditions. Here, we offer an answer to this inverse problem posed by the question below. Given a micro pin-fin array cooling with these constraints: - given maximum allowable temperature of the material, - given inlet cooling fluid temperature, - given total pressure loss (pumping power affordable), and - given overall thickness of the entire electronic component, find out the maximum possible average heat flux on the hot surface and find the maximum possible heat flux at the hot spot under the condition that the entire amount of the inputted heat is completely removed by the cooling fluid. This problem was solved using multi-objective constrained optimization and metamodeling for an array of micro pin-fins with circular, airfoil and symmetric convex cross sections that is removing all the heat inputted via uniform background heat flux and by a hot spot. The goal of this effort was to identify a cooling pin-fin shape and scheme that is able to push the maximum allowable heat flux as high as possible without the maximum temperature exceeding the specified limit for the given material. Conjugate heat transfer analysis was performed on each of the randomly created candidate configurations. Response surfaces based on Radial Basis Functions were coupled with a genetic algorithm to arrive at a Pareto frontier of best trade-off solutions. The Pareto optimized configuration indicates the maximum physically possible heat fluxes for specified material and constraints.

scholarly journals Ice front blocking of ocean heat transport to an Antarctic ice shelf

2020 ◽  
Author(s):  
Anna Wåhlin ◽  
Nadine Steiger ◽  
Elin Darelius ◽  
Karen Assmann ◽  
Mirjam Glessmer ◽  
...  
Keyword(s):  
Heat Flux ◽  
Continental Shelf ◽  
Laboratory Experiments ◽  
Heat Fluxes ◽  
Density Structure ◽  
Ocean Water ◽  
Ocean Heat Transport ◽  
Ice Shelf ◽  
Rotating Platform ◽  
Oceanic Heat Flux

<p>Shoreward oceanic heat flux in deep channels on the continental shelf typically far exceeds that required to match observed ice shelf melt rates, suggesting other critical controls.  IN the present study we study the depth-independent (barotropic) and the density-driven (baroclinic) components of the flow of warm ocean water towards an ice shelf. Using observations from the Getz Ice Shelf system as well as geophysical laboratory experiments on a rotating platform, it is shown that the dramatic step shape of the ice front blocks the barotropic component, and that only the baroclinic component, typically much smaller, can enter the sub-ice cavity.  A similar blocking of the barotropic component may occur in other areas with comparable ice-bathymetry configurations, which may explain why changes in the density structure of the water column have been found to be a better indicator of basal melt rate variability than the heat transported onto the continental shelf. Representing the step topography of the ice front accurately in models is thus important for simulating the ocean heat fluxes and induced melt rates.</p>

How Much Do Different Land Models Matter for Climate Simulation? Part I: Climatology and Variability

2010 ◽  
Vol 23 (11) ◽  
pp. 3120-3134 ◽  
Author(s):  
Jiangfeng Wei ◽  
Paul A. Dirmeyer ◽  
Zhichang Guo ◽  
Li Zhang ◽  
Vasubandhu Misra
Keyword(s):  
Heat Flux ◽  
Surface Temperature ◽  
Latent Heat ◽  
General Circulation ◽  
Surface Fluxes ◽  
Heat Fluxes ◽  
Maximum Temperature ◽  
Daily Maximum Temperature ◽  
Time Step ◽  
The Impact

Abstract An atmospheric general circulation model (AGCM) is coupled to three different land surface schemes (LSSs), both individually and in combination (i.e., the LSSs receive the same AGCM forcing each time step and the averaged upward surface fluxes are passed back to the AGCM), to study the uncertainty of simulated climatologies and variabilities caused by different LSSs. This tiling of the LSSs is done to study the uncertainty of simulated mean climate and climate variability caused by variations between LSSs. The three LSSs produce significantly different surface fluxes over most of the land, no matter whether they are coupled individually or in combination. Although the three LSSs receive the same atmospheric forcing in the combined experiment, the inter-LSS spread of latent heat flux can be larger or smaller than the individually coupled experiment, depending mostly on the evaporation regime of the schemes in different regions. Differences in precipitation are the main reason for the different latent heat fluxes over semiarid regions, but for sensible heat flux, the atmospheric differences and LSS differences have comparable contributions. The influence of LSS uncertainties on the simulation of surface temperature is strongest in dry seasons, and its influence on daily maximum temperature is stronger than on minimum temperature. Land–atmosphere interaction can dampen the impact of LSS uncertainties on surface temperature in the tropics, but can strengthen their impact in middle to high latitudes. Variations in the persistence of surface heat fluxes exist among the LSSs, which, however, have little impact on the global pattern of precipitation persistence. The results provide guidance to future diagnosis of model uncertainties related to LSSs.

Investigation of Cooling Performance of a Swirl Microchannel Heat Sink by Numerical Simulation

2011 ◽  
Author(s):  
Yanfeng Fan ◽  
Ibrahim Hassan
Keyword(s):  
Numerical Simulation ◽  
Heat Flux ◽  
Heat Sink ◽  
High Heat ◽  
Heat Fluxes ◽  
Maximum Temperature ◽  
Microchannel Heat Sink ◽  
Irreversible Damage ◽  
Cooling Performance ◽  
Large Heat

High heat fluxes have been created by the semiconductor devices due to the high power generation and shrank size. The large heat flux causes the circuit to exceed its allowable temperature and may experience both working efficiency loss and irreversible damage due to excess in their temperatures. In this paper, a swirl microchannel heat sink is designed to dissipate the large heat flux from the devices. The numerical simulation is carried out to investigate the cooling performance. Uniform heating boundary condition is applied and single phase water is selected as coolant. The present micro heat sink applies multiple swirl microchannels positioned in a circular flat plate to enhance the heat convection by creating the secondary flow at high Reynolds numbers. Copper is selected as the material of heat sink. The channel depth and width are fixed as 0.5 mm and 0.4 mm, respectively. The heat is injected into the system from the bottom of heat sink at the heat fluxes from 10 to 60 W/cm2. Flow is supplied from the top of micro heat sink through a jet hole with a diameter of 2 mm and enters swirl microchannels at the volume flow rates varying from 47 to 188 ml/min. The cooling performances of swirl microchannel heat sinks with different curvatures and channel numbers are evaluated based on the targets of low maximum temperature, temperature gradient and pressure drop.

The Effectiveness of Solar Shield for Outdoor Equipment

2003 ◽  
Author(s):  
Mulugeta K. Berhe ◽  
Younes Shabany
Keyword(s):  
Heat Flux ◽  
Vertical Plate ◽  
Heat Fluxes ◽  
Maximum Temperature ◽  
Heated Plate ◽  
Surface Emissivity ◽  
Cfd Simulations ◽  
Sky Temperature ◽  
Flow Effects ◽  
Solar Heat Flux

The effect of solar shield on the maximum temperature of an active plate was investigated. The focus of this analysis was to determine conditions under which it was advantageous to have a solar shield around a heated plate. Heat transfer correlations for free convection around a vertical plate were used with some corrections for channel flow effects. Results obtained from these correlations were validated using CFD simulations. The results presented in this paper include the effects of some key parameters on the maximum temperature of the active plate, including the effects of heat fluxes from the active plate and solar shield, surface emissivity and sky temperature. The results suggest that there is a limit on the ratio of heat flux from the active plate to the solar heat flux beyond which it is not advantageous to have a solar shield. The results also show that the advantage of having a solar shield diminishes as the effective sky temperature decreases. Furthermore, the emissivity is an important factor and its value can determine whether a solar shield is necessary or not.

Study on the Thermal Contact Zone in the Surface Grinding

2011 ◽  
Vol 188 ◽  
pp. 523-528
Author(s):  
Chong Lue Hua ◽  
Gui Cheng Wang ◽  
Hong Jie Pei ◽  
Gang Liu
Keyword(s):  
Heat Flux ◽  
Temperature Field ◽  
Thermal Contact ◽  
Heat Fluxes ◽  
Grinding Temperature ◽  
The Finite Element Method ◽  
Temperature Dependent ◽  
Convection Model ◽  
Temperature Dependent Properties ◽  
Circular Heat

The present study aims to investigate the temperature field by using the different heat fluxes, such as rectangle heat flux, triangular heat flux, inclined triangular heat flux, circular heat flux. To obtain a reliable figure of temperature field induced by grinding, temperature-dependent properties of work materials were taken into account and a convection model with an effective cooling factor was introduced. A thorough analysis using the finite element method showed that predictions were very agreed with the results of the experiment. Finally, the present paper showed that the contact angle must be taken into account in future models.

scholarly journals Efficient Series Expansions of the Temperature Field in Dry Surface Grinding for Usual Heat Flux Profiles

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Juan Luis González-Santander
Keyword(s):  
Heat Flux ◽  
Temperature Field ◽  
Numerical Evaluation ◽  
Numerical Procedure ◽  
Constant Heat Flux ◽  
Surface Grinding ◽  
Maximum Temperature ◽  
Series Expansions ◽  
Constant Heat ◽  
Flux Profile

In the framework of Jaeger’s model for heat transfer in dry surface grinding, series expansions for calculating the temperature field, assuming constant, linear, triangular, and parabolic heat flux profiles entering into the workpiece, are derived. The numerical evaluation of these series is considerably faster than the numerical integration of Jaeger’s formula and as accurate as the latter. Also, considering a constant heat flux profile, a numerical procedure is proposed for the computation of the maximum temperature as a function of the Peclet number and the depth below the surface. This numerical procedure has been used to evaluate the accuracy of Takazawa’s approximation.

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