Predicting charring rate of woods exposed to time-increasing and constant heat fluxes

2008 ◽  
Vol 81 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Yang Lizhong ◽  
Zhou Yupeng ◽  
Wang Yafei ◽  
Guo Zaifu
Keyword(s):  
Heat Fluxes ◽  
Constant Heat ◽  
Charring Rate

Variations of Buoyancy-Induced Mass Flux From Single-Phase to Two-Phase Flow in a Vertical Porous Tube With Constant Heat Flux

1999 ◽  
Vol 121 (3) ◽  
pp. 646-652 ◽  
Author(s):  
T. S. Zhao ◽  
Q. Liao ◽  
P. Cheng
Keyword(s):  
Heat Flux ◽  
Mass Flux ◽  
Single Phase ◽  
Two Phase Flow ◽  
Constant Heat Flux ◽  
Heat Fluxes ◽  
Phase Flow ◽  
Constant Heat ◽  
Two Phase ◽  
Porous Tube

This paper presents an experimental study of a buoyancy-induced flow of water with phase-change heat transfer in a vertical porous tube heated at a constant heat flux. Experiments were carried out from subcooled liquid flow to connective boiling by varying the imposed heat fluxes. At a prescribed heat flux the steady-state mass flux of water, as well as the temperatures along the tube wall and along the centerline of the packed tube, were measured. It is shown that for both single-phase flow and the two-phase flow with a rather low vapor fraction, the induced mass flux increased as the heat flux was increased. However, as the imposed heat flux was increased further, the induced mass flux dropped drastically, and remained relatively constant afterwards. The influences of various parameters such as the porous tube diameter, the particle sizes, and the hydrostatic head on the induced mass flux are also examined.

Heat Flow Transducer Responses to Hyperbaric Environments

1980 ◽  
Vol 102 (3) ◽  
pp. 247-252 ◽  
Author(s):  
M. L. Nuckols
Keyword(s):  
Heat Flow ◽  
Ambient Pressure ◽  
Heat Fluxes ◽  
Constant Heat ◽  
Flow Transducer ◽  
Ambient Temperatures ◽  
Temperature And Pressure ◽  
Environmental Temperatures ◽  
Body Heat ◽  
Hyperbaric Conditions

The responses of heat flow transducers, used in the evaluation of convective body heat losses, have been investigated at hyperbaric environments. Environmental temperatures, pressures, and gas composition were varied while transducer responses to constant heat fluxes were observed. Ambient temperatures were varied between 3° and 40° C. Ambient pressures were varied between simulated depths of 0 and 1000 feet of seawater (445 psi). Transducer responses to heat fluxes varying between 0 and 250 watts/m2 are reported in the above temperature and pressure ranges within atmospheres of helium, nitrogen, and air. Ambient pressure variations were found to have little effect on the response of the heat flow transudcers to a constant heat source once appropriate temperature corrections were made. However, transducer response variations of up to 14 percent were observed when environmental gas compositions were varied at hyperbaric conditions.

scholarly journals Numerical Investigation of Conjugate Heat Transfer in Rectangular Micro-Channel Heat Sinks under Laminar Flow Conditions

2018 ◽  
Vol 1 (1) ◽  
pp. 196-205
Author(s):  
Haluk Anıl Köse ◽  
Alperen Yıldızeli ◽  
Gökhan Canbolat ◽  
Sertaç Çadırcı
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Heat Transfer Enhancement ◽  
Heat Fluxes ◽  
Heat Sinks ◽  
Micro Channel ◽  
Flow Conditions ◽  
Transfer Enhancement ◽  
Constant Heat ◽  
Laminar Flow Conditions

In this study, numerical calculations are performed to investigate steady, laminar convective heat transfer characteristics in rectangular micro channel heat sinks under constant heat fluxes. The investigations are performed at three different inlet Reynolds numbers (400,600 and 800) and constant heat fluxes (500, 1000 and 2000 kW/m2). The aspect ratios of the rectangular micro-channel are selected 1, 1.5 and 2 in the laminar flow regime, respectively. Heat transfer enhancement is the main objective of the study. Nusselt number variation and the pressure drops are found for the given parameters to find the best heat transfer enhancement. It is found that a micro-channel heat sink with square cross-sectional area can be used as an adequate configuration under laminar flow conditions.

Implementations of Deflectors to Improve the Performance of Heat Sinks

2012 ◽  
Author(s):  
J. P. Ramirez-Vazquez ◽  
A. Hernandez-Guerrero ◽  
J. L. Zuñiga-Cerroblanco ◽  
J. C. Rubio-Arana
Keyword(s):  
Heat Sink ◽  
Numerical Study ◽  
Electronic Devices ◽  
Constant Heat Flux ◽  
Heat Fluxes ◽  
Heat Sinks ◽  
Hydrodynamic Behavior ◽  
Constant Heat ◽  
Pin Fin ◽  
Global Performance

This work presents a numerical study of the thermal and hydrodynamic behavior of a pin-fin heat sink where deflectors are placed along the flow of the coolant air; the effect of the arrangement of the fins and deflectors in the global performance of the heat sink is investigated. The fin geometry analyzed is rectangular, and the arrangement of the fins is inline. The heat sink is placed in a channel in which air flows, and a constant heat flux is applied at the bottom wall of the heat sink with values equivalent to the heat fluxes generated by current electronic devices. Deflectors are placed in the top of the channel in order to drive the air flow into the front and end of the heat sink. The results for the Nusselt number and for the pressure drop along the heat sink are reported. The best dimension of deflectors and pitch for the arrangement based on the thermal and hydraulic performance is attained.

Design and Testing of a Natural Convection Experimental Setup on the External Surface of Heated Inclined Cylinders With a Constant Heat Flux Boundary Condition: Tests for Naked Cylinders

Volume 1 ◽  
2004 ◽  
Author(s):  
Jaime Antonio Sa´nchez Baquerizo ◽  
Jorge W. Duque Rivera
Keyword(s):  
Boundary Condition ◽  
Heat Flux ◽  
Natural Convection ◽  
Convection Heat Transfer ◽  
Constant Heat Flux ◽  
Heat Fluxes ◽  
Experimental Setup ◽  
Constant Heat ◽  
Flux Boundary Condition ◽  
Heat Flux Boundary Condition

An experimental setup for natural convection heat transfer from inclined heated cylinders with a constant heat flux boundary condition has been designed and tested for various heat fluxes and inclination angles. For the horizontal cylinder experiment the results are in good agreement with [2] within the range of Ra* (1E5 to 1E6). For the variable inclination experiments, comparisons were made with a correlation available for inclined isothermal cylinders [1]. It was observed, that although the boundary conditions that have been compared are different, the decreasing tendency of the Nusselt number holds as the inclination of the cylinder increases. The results have been correlated in an experimental equation shown at the end of this paper.

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