THE INFLUENCE OF SURFACE HEAT FLUX DISTRIBUTION AND SURFACE TEMPERATURE DISTRIBUTION ON TURBULENT FORCED CONVECTIVE HEAT TRANSFER IN CLUSTERS OF TUBES IN WHICH THE FLOW OF COOLANT IS PARALLEL TO THE AXES OF THE TUBES

2019 ◽  
Author(s):  
J. D. Redman ◽  
G. McKee ◽  
I. C. Rule
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Temperature Distribution ◽  
Surface Temperature ◽  
Surface Heat Flux ◽  
Flux Distribution ◽  
Surface Heat ◽  
Heat Flux Distribution ◽  
Forced Convective Heat Transfer ◽  
Surface Temperature Distribution

Research on the Protection of Forward-Facing Cavity on the Flow Field of Low Total Pressure Opposing Jet

2014 ◽  
Vol 684 ◽  
pp. 335-340 ◽  
Author(s):  
Hai Bo Lu ◽  
Leng Han
Keyword(s):  
Heat Flux ◽  
Flow Field ◽  
Surface Heat Flux ◽  
Total Pressure ◽  
Flux Distribution ◽  
Surface Heat ◽  
Numerical Results ◽  
Cooling Effect ◽  
Heat Flux Distribution ◽  
Stable Flow

This paper focus on the detailed influence of forward-facing cavity on the opposing jet. The flow field of a hemisphere nose-tip with the combined configuration was simulated numerically and the surface heat flux distribution was obtained. The numerical results show that a suitable cavity is helpful for the opposing jet. With the same total pressure, the single opposing jet even can’t form a stable flow field and there is no cooling effect.

Instantaneous Local Heat Flux Measurements in a Small Utility Engine

2009 ◽  
Author(s):  
Terry Hendricks ◽  
Jaal Ghandhi ◽  
John Brossman
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Numerical Model ◽  
Surface Temperature ◽  
Heat Transfer Rate ◽  
Surface Heat Flux ◽  
Transfer Rate ◽  
Surface Heat ◽  
High Load ◽  
Flux Measurements

Heat flux measurements were performed in an air-cooled utility engine using a fast-response coaxial-type surface thermocouple. The surface heat flux was calculated using both analytical and numerical models. The heat flux was found to be a strong function of engine load. The peak heat flux and initial heat flux rise rate increase with engine load. The measured heat flux data were used to estimate a global heat transfer rate, and this was compared with the heat transfer rate calculated by a single-zone heat release analysis. The measured values of heat transfer were higher than the calculated values largely because of the lack of spatial averaging. The high load data showed an unexplainable negative heat flux during the expansion stroke while the gas temperature was still high. A 1D and 2D finite difference numerical model utilizing an adaptive timestep Crank-Nicholson (CN) integration routine was developed to investigate the surface temperature measurement. Applying the measured surface temperature profile to the 1D model, the resultant surface heat flux showed excellent agreement with the analytical inversion solution and captured the reversal of the energy flow back into the cylinder during the expansion stroke. The 2D numerical model was developed to observe transient lateral conduction effects within the probe and incorporated the various materials used in the construction and assembly of the heat flux sensor. The resulting average heat flux profile for the test case is shown to be slightly higher in peak and longer in duration when compared with the results from the 1D analytical inversion, and this is attributed to contributions from the high thermal diffusivity constituents in the sensor. Furthermore, the negative heat flux at high load was not eliminated suggesting that factors other than lateral conduction may be affecting the measurement accuracy.

Numerical Simulation of the Thermal Performance of Cable Radiant Heating Floors with Different Structure

2012 ◽  
Vol 512-515 ◽  
pp. 3047-3050
Author(s):  
Quan Ying Yan ◽  
Li Li Jin
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Surface Heat Flux ◽  
Optimization Design ◽  
Flux Distribution ◽  
Heat Transfer Process ◽  
Surface Heat ◽  
Radiant Heating ◽  
Heat Flux Distribution ◽  
Ansys Software

In this paper, three kinds of mathematical models of cable heated radiant floors were established, and numerical simulation of heat transfer process for these heated floors were carried on by using finite element method and ANSYS software. The rule of temperature distribution, surface heat flux distribution and downward heat loss of these three floor structures were given and compared. The results can provide references for a further optimization, design and application of low temperature radiant heating floor.

Influence of Space-Varying Surface Heat Flux on the Heat Transfer Due to a Moving Fluid Over a Moving Surface

2013 ◽  
Vol 135 (8) ◽  
Author(s):  
Swati Mukhopadhyay ◽  
Iswar Chandra Mondal ◽  
Kuppalapalle Vajravelu ◽  
Robert A. Van Gorder
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Flux ◽  
Power Law ◽  
Surface Heat Flux ◽  
Flat Surface ◽  
Similarity Solutions ◽  
Surface Heat ◽  
Forced Convective Heat Transfer ◽  
Moving Fluid

Boundary-layer forced convective heat transfer at a moving flat surface parallel to a moving stream is presented for the case where the plate is subjected to a variable heat flux. In particular, we assume that the surface heat flux varies with spatial variable x according to a power-law rule. The similarity solutions for the problem are obtained by solving the reduced ordinary differential equations numerically, while exact solutions are provided for certain parametric values. It is noted that even in the case of prescribed surface heat flux, dual solutions exist when the surface and the fluid move in opposite directions.

Proposed Experimental Technique for Measuring Heat Transfer Coefficients Using a Pulsed Periodic Surface Heat Flux

1999 ◽  
Author(s):  
Wayne N. O. Turnbull ◽  
William E. Carscallen
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Surface Temperature ◽  
Phase Behavior ◽  
Experimental Technique ◽  
Surface Heat Flux ◽  
Surface Heat ◽  
Transfer Coefficients ◽  
Periodic Surface ◽  
Heat Transfer Coefficients

Abstract An analytical and numerical investigation has been carried out to ascertain the possibility of using a pulsed periodic surface heat flux to measure local surface heat transfer coefficients. The proposed technique is an extension of a previously proven experimental method. It is based upon the premise that the harmonics of a surface temperature response to an imposed periodic pulse will display phase shifting behavior that is a function of the thermophysical properties of the surface, the local heat transfer coefficient and the harmonic frequency. The phase behavior is not a function of the magnitude of the energy deposited by the pulse. Since phase behavior is being investigated there is no requirement to calibrate the surface temperature-sensing device. The numerical solution confirms the analytical results, which were obtained using a non-rigorous mathematical assumption. Results indicate that in order to maximize the sensitivity of the proposed experimental technique the pulse frequency should be kept low, the surface layer thin and the substrate thermal conductivity and diffusivity as low as possible.

Measurement of Surface Heat Flux and Surface Temperature in Nucleate Pool Boiling Using Micro-Thermocouples

2009 ◽  
Author(s):  
Wei Liu ◽  
Kazuyuki Takase
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Surface Temperature ◽  
Temperature Change ◽  
Surface Heat Flux ◽  
Heat Conduction Problem ◽  
Pool Boiling ◽  
Surface Heat ◽  
Heat Transfer Analysis ◽  
Boiling Process

In this paper, a measurement system for surface temperature and surface heat flux was developed to study heat transfer mechanism in boiling process. The system was consisted by two parts: (1) inner block temperatures were measured using micro-thermocouples set at two layers inside heating block; (2) with using the measured temperatures, inverse heat transfer analysis was performed to get surface heat flux and surface temperature. For the inner block temperature measurement, special T-type micro thermocouples with a common positive pole were developed. Totally 20 thermocouples were set at two layers at the depths 3.1μm and 4.905mm beneath the boiling surface, in a radius of 5mm. The developed system was used to research the change of surface heat flux and surface temperature in a boiling process. Experiments were performed to pool boiling at atmospheric pressure. The experiments showed the developed special T-type micro thermocouples could trace temperature change in boiling process successfully. With comparison to images from a high-speed camera, temperature change tendencies in boiling process were tried to understand. Then one dimensional inverse heat conduction problem was solved to get surface heat flux and surface temperature. Increase in surface heat flux with the generation of big bubble was derived successfully.

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