Film evaporation from a micro-grooved surface - An approximate heat transfer model and its comparison with experimental data

10.2514/3.215 ◽  
1990 ◽  
Vol 4 (4) ◽  
pp. 512-520 ◽  
Author(s):  
X. Xu ◽  
V. P. Carey
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Film Evaporation ◽  
Grooved Surface ◽  
Comparison With Experimental Data

Experimental Investigation of Heat Transfer in Impingement Air Cooled Plate Fin Heat Sinks

2005 ◽  
Vol 128 (4) ◽  
pp. 412-418 ◽  
Author(s):  
Zhipeng Duan ◽  
Y. S. Muzychka
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Thermal Resistance ◽  
Thermal Performance ◽  
Heat Transfer Model ◽  
Heat Sinks ◽  
Transfer Model ◽  
Transfer Coefficients ◽  
Developing Flow ◽  
Rectangular Channels

Impingement cooling of plate fin heat sinks is examined. Experimental measurements of thermal performance were performed with four heat sinks of various impingement inlet widths, fin spacings, fin heights, and airflow velocities. The percent uncertainty in the measured thermal resistance was a maximum of 2.6% in the validation tests. Using a simple thermal resistance model based on developing laminar flow in rectangular channels, the actual mean heat transfer coefficients are obtained in order to develop a simple heat transfer model for the impingement plate fin heat sink system. The experimental results are combined into a dimensionless correlation for channel average Nusselt number Nu∼f(L*,Pr). We use a dimensionless thermal developing flow length, L*=(L∕2)∕(DhRePr), as the independent parameter. Results show that Nu∼1∕L*, similar to developing flow in parallel channels. The heat transfer model covers the practical operating range of most heat sinks, 0.01<L*<0.18. The accuracy of the heat transfer model was found to be within 11% of the experimental data taken on four heat sinks and other experimental data from the published literature at channel Reynolds numbers less than 1200. The proposed heat transfer model may be used to predict the thermal performance of impingement air cooled plate fin heat sinks for design purposes.

Development of a New Heat Transfer Model Near the Quench Front in the Reflooding Phase of a Tight Lattice

2012 ◽  
Author(s):  
Dan Wu ◽  
Hongxing Yu ◽  
Junchong Yu ◽  
Jie Li ◽  
Jiyang Yu
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Liquid Film ◽  
Temperature Drop ◽  
Transfer Model ◽  
Heat Transfer Mode ◽  
Transfer Mode ◽  
Film Evaporation ◽  
Quench Temperature ◽  
Tight Lattice

Heat transfer characteristics near the quench front in a reflooding process are quite complex. Large amount of vapor are generated, and the rod clad temperature drops rapidly to near saturation state. Until now, heat transfer mechanism in this region has not been well understood yet. Best estimate codes like RELAP5, COBRA-TF tend to treat the heat transfer mode near the quench front as transition boiling. However, when calculating the reflooding phase of tight lattice, these codes always under-predict the quench temperature, and also the slop of the temperature drop is predicted to be less steep than the experimental data. In this paper, a new heat transfer model near the quench front in the reflooding phase of a tight lattice is developed. Instead of transition boiling, transient liquid film evaporation is considered to be the main heat transfer mode in this region. It is supposed that heat released near the quench front is through liquid film evaporation. Through comparisons with experimental data, it can be concluded that the new model can better predict the quench temperature and the temperature drop slop.

Isentropic Compressor Efficiency Calculation Method for Small Gasoline Engine Turbocharger Using Supplier Performance Maps

2021 ◽  
Author(s):  
Georges Salameh ◽  
Guillaume Goumy ◽  
Pascal Chesse
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Gasoline Engine ◽  
Experimental Tests ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Flow Equations ◽  
Adiabatic Flow ◽  
Efficiency Calculation ◽  
Isentropic Efficiency

Abstract A turbocharger efficiency performance map given by the supplier is calculated using adiabatic flow equations and non-adiabatic experimental data. The experimental data used for this calculation is measured in hot gas stand conditions which are not adiabatic and the efficiency calculation needs correction. This paper presents a method to correct the isentropic efficiency of a compressor using the supplier maps and a heat transfer model applied on the compressor. Water is circulating in the central housing to cool the turbocharger and this water flow could be considered as insulation for heat transfer between the compressor and the turbine. The thermal effect of the turbine on the compressor is then neglected and the compressor heat flux is calculated and used to correct the isentropic efficiency calculation. The heat transfer is considered between the compressor and the surrounding environment and between the compressor and the central housing. Experimental adiabatic measurements are used to validate the model. Experimental tests are carried with different oil and water temperatures combinations to test the accuracy of the heat transfer model with these different combinations.

An Analytical Model for Turbulent Compression-Driven Heat Transfer

1998 ◽  
Vol 120 (3) ◽  
pp. 617-623 ◽  
Author(s):  
F. J. Cantelmi ◽  
D. Gedeon ◽  
A. A. Kornhauser
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Transfer Coefficient ◽  
Analytical Solution ◽  
Power Loss ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Mixing Length ◽  
Power Losses ◽  
Flow Configurations

Compression-driven heat transfer is important to the performance of many reciprocating energy-conversion machines. For small pressure variations in cylinder spaces without inflow, heat transfer and power losses are well predicted using a simple heat transfer model which neglects turbulence. In actual engine cylinders, where significant turbulence levels can be generated by high-velocity inflow, a model which neglects turbulence may not be adequate. In this paper, a heat transfer model having an analytical solution is developed for turbulent cylinder spaces based on a mixing length turbulence model. The model is then used to develop expressions for heat-transfer-related power loss and heat transfer coefficient. Predicted results compare favorably with experimental data for two in-flow configurations.

Heat Transfer Model for Evaporation of Elongated Bubble Flows in Microchannels

2002 ◽  
Vol 124 (6) ◽  
pp. 1131-1136 ◽  
Author(s):  
Anthony M. Jacobi ◽  
John R. Thome
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Flow Boiling ◽  
Heat Transfer Model ◽  
Transfer Mechanism ◽  
Transfer Model ◽  
Heat Transfer Mechanism ◽  
New Model ◽  
Thin Film Evaporation ◽  
Film Evaporation

Recent experimental studies of evaporation in microchannels have shown that local flow-boiling coefficients are almost independent of vapor quality, weakly dependent on mass flux, moderately dependent on evaporating pressure, and strongly dependent on heat flux. In a conventional (macrochannel) geometry, such trends suggest nucleate boiling as the dominant heat transfer mechanism. In this paper, we put forward a simple new heat transfer model based on the hypothesis that thin-film evaporation into elongated bubbles is the important heat transfer mechanism in these flows. The new model predicts the above trends and quantitatively predicts flow-boiling coefficients for experimental data with several fluids. The success of this new model supports the idea that thin-film evaporation into elongated bubbles is the important heat transfer mechanism in microchannel evaporation. The model provides a new tool for the study of such flows, assists in understanding the heat transfer behavior, and provides a framework for predicting heat transfer.

Theoretical Post-Dryout Heat Transfer Model

2018 ◽  
Vol 1 (1) ◽  
pp. 142-150
Author(s):  
Murat Tunc ◽  
Ayse Nur Esen ◽  
Doruk Sen ◽  
Ahmet Karakas
Keyword(s):  
Heat Transfer ◽  
Droplet Diameter ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Operating Pressure ◽  
Vertical Pipe ◽  
Two Phase ◽  
Experimental Values ◽  
Reactor Operating ◽  
Coolant System

A theoretical post-dryout heat transfer model is developed for two-phase dispersed flow, one-dimensional vertical pipe in a post-CHF regime. Because of the presence of average droplet diameter lower bound in a two-phase sparse flow. Droplet diameter is also calculated. Obtained results are compared with experimental values. Experimental data is used two-phase flow steam-water in VVER-1200, reactor coolant system, reactor operating pressure is 16.2 MPa. On heater rod surface, dryout was detected as a result of jumping increase of the heater rod surface temperature. Results obtained display lower droplet dimensions than the experimentally obtained values.

An Engine Heat Transfer Model for Comprehensive Thermal Simulations

2006 ◽  
Author(s):  
Filip Kitanoski ◽  
Wolfgang Puntigam ◽  
Martin Kozek ◽  
Josef Hager
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Thermal Simulations
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