scholarly journals A Method of Experimental Studies of Heat Transfer Processes between Adjacent Facilities

2018 ◽  
Vol 7 (4.3) ◽  
pp. 288 ◽  
Author(s):  
Vadym Nizhnyk ◽  
Stanislav Shchipets ◽  
Olexandr Tarasenko ◽  
Vitalii Kropyvnytskyi ◽  
Bogdan Medvid
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Test Specimen ◽  
Experimental Studies ◽  
Ground Surface ◽  
Heat Radiation ◽  
Lower Edge ◽  
Specimen Type ◽  
Transfer Processes ◽  
Window Opening

A method of experimental studies of heat transfer processes between adjacent facilities during fire was developed. Equipment necessary for the experimental studies was determined. A new specimen type for studies was created in order to perform experimental studies. Configuration of the specimen for the studies allows simulation of a building fragment with filler structures which is affected by heat radiation emitted by fire. Points of placement of the specimens for studies relative to the heat flux source when conducting experimental studies were substantiated. It was revealed that height of the specimen installation shall be determined so that the test specimen is located below the flame tip in order to take into account the most severe impact of heat radiation coming from the fire bed and to exclude any possibility of irradiation from the ground surface. It was proposed that the test specimens are placed at the level of the lower edge of the window opening of the building fragment at the distances of2 m,4 mand6 mfrom the building fragment. The sequence of conduction of experimental studies of heat transfer processes between adjacent facilities during fire was developed. 

scholarly journals A method of experimental studies of heat transfer processes between industrial constructions

2018 ◽  
Vol 230 ◽  
pp. 02021
Author(s):  
Vadym Nizhnyk ◽  
Oksana Kyrychenko ◽  
Olexandr Tarasenko ◽  
Andrii Shvydenko ◽  
Serhii Hovalenkov
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Flux Density ◽  
Experimental Studies ◽  
Heat Radiation ◽  
Ambient Conditions ◽  
Transfer Processes ◽  
Density Values ◽  
New Type ◽  
The One

A method of experimental study of heat transfer processes between industrial constructions during a fire was developed. Types of equipment necessary for the conduction of the experimental studies were determined. A new type of specimen to be used as the one to be studied when conducting experimental studies was developed. Installation sites of thermocouples and heat flux detector on the specimen under study are shown as layout. Installation sites of the specimens under study relative to heat radiation source were substantiated experimentally. Succession of the conduction of the experimental studies of heat transfer processes between industrial constructions during a fire was developed which consists of the following procedures: production of specimens for the studies, measurement and recording on ambient conditions, measuring of temperature and heat flux on the surface of the specimen under study, and filling 55B test fire with water and diesel fuel. It was established that average temperatures and heat flux density values as well as flame geometry should be measured when performing experimental studies.

scholarly journals Daytime Heat Transfer Processes Related to Slope Flows and Turbulent Convection in an Idealized Mountain Valley

2010 ◽  
Vol 67 (11) ◽  
pp. 3739-3756 ◽  
Author(s):  
Stefano Serafin ◽  
Dino Zardi
Keyword(s):  
Heat Transfer ◽  
Ground Surface ◽  
Turbulent Convection ◽  
Mountain Valley ◽  
Transfer Processes ◽  
Slope Winds ◽  
Large Eddy ◽  
Thermally Driven ◽  
Slope Wind ◽  
The Impact

Abstract The mechanisms governing the daytime development of thermally driven circulations along the transverse axis of idealized two-dimensional valleys are investigated by means of large-eddy simulations. In particular, the impact of slope winds and turbulent convection on the heat transfer from the vicinity of the ground surface to the core of the valley atmosphere is examined. The interaction between top-down heating produced by compensating subsidence in the valley core and bottom-up heating due to turbulent convection is described. Finally, an evaluation of the depth of the atmospheric layer affected by the slope wind system is provided.

Large Heat Transport Due to Spontaneous Gas Oscillation Induced in a Tube With Steep Temperature Gradients

1983 ◽  
Vol 105 (4) ◽  
pp. 889-894 ◽  
Author(s):  
T. Yazaki ◽  
A. Tominaga ◽  
Y. Narahara
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Liquid Helium ◽  
Heat Conductivity ◽  
Room Temperature ◽  
Evaporation Rate ◽  
Experimental Studies ◽  
Temperature Gradients ◽  
Pressure Amplitude ◽  
Large Heat

This paper describes experimental studies of heat transfer due to the oscillations of gas columns that are spontaneously induced in a tube with steep temperature gradients. The tube (∼3 m in length) is closed at both ends and bent into U-shaped form at the midpoint. The temperature distribution along the tube is step-functional and symmetrical with respect to the midpoint. The warm part (closed-end sides) is maintained at room temperature and the cold one is immersed in liquid helium (4.2 K). The heat transported from the warm part to the cold is estimated from the evaporation rate of liquid helium. The heat flux by the oscillations is proportional to the square of the pressure amplitude, and the effective heat conductivity can be several orders of magnitude larger than the molecular heat conductivity of gas. The experimental results are compared with the theory of the second-order heat flux proposed by Rott and are found to be in satisfactory agreement with this.

scholarly journals Heat Balance of Horizontal Ground Heat Exchangers

2018 ◽  
Vol 25 (4) ◽  
pp. 537-548
Author(s):  
Krzysztof Kupiec ◽  
Monika Gwadera
Keyword(s):  
Heat Transfer ◽  
Boundary Condition ◽  
Heat Flux ◽  
Ambient Temperature ◽  
Heat Balance ◽  
Heat Exchangers ◽  
Ground Surface ◽  
Temporal Variations ◽  
Moisture Evaporation ◽  
Ground Heat Exchangers

Abstract This work refers to the modelling of heat transfer in horizontal ground heat exchangers. For different conditions of collecting heat from the ground and different boundary condition profiles of temperature in the ground were found, and temporal variations of heat flux transferred between the ground surface and its interior were determined. It was taken into account that this flux results from several different mechanisms of heat transfer: convective, radiative, and that connected with moisture evaporation. It was calculated that ground temperature at great depths is greater than the average annual ambient temperature.

scholarly journals EFFECT OF CAVITY RATIO ON HEAT TRANSFER BY FREE LOAD FROM HEATED PLATES UPWARD WITH CONSTANT HEAT FLUX

2021 ◽  
Vol 9 (12) ◽  
pp. 686-695
Author(s):  
Waleed Abdulhadiethbayah ◽  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Nusselt Number ◽  
Free Convection ◽  
Electronic Devices ◽  
Experimental Studies ◽  
Constant Heat Flux ◽  
Rate Of Change ◽  
Constant Heat ◽  
The Difference

Many engineering and industrial applications always seek to find ways to dissipate heat from heated surfaces used in these industries. As it is involved in the cooling of electronic parts and electrical transformers, as well as the design of solar collectors, in addition to being a process of heat exchange between hot surfaces and the fluids in contact with them. Since most electronic devices or their parts are cooled by removing the heat generated inside them by using air as a heat transfer medium and in a free convection way, and the fact that heat transfer by free convection occurs in many fields, so there were many studies that dealt with this topic. The free load is generated by the buoyant force (Bouncy force) As a result of the difference in the density of the fluid adjacent to the heated surface due to the difference in temperatures between the fluid and the surface. The laminar flow along surfaces has been extensively studied analytically [1,2,3,4] In the horizontal, inclined and vertical case, whether by constant heat flux or constant surface temperature, there are also many experimental studies of heat transfer by free convection from horizontal, inclined and vertical surfaces with constant heat flux or constant surface temperature [5,6,7,8]. Some experimental studies have also been conducted on heat transfer by convection from heated surfaces in the form of a disk (ring)The outcome of these studies was to extract an exponential mathematical relationship between the average of Nusselt number and the Kirchhoff number or Rayleigh number and the following formula: (Nu=C(Ra) n It is one of the most suitable formulas for heat transfer by free convection from heated surfaces in all its forms and over a wide range of Rayleigh number . It is noted that not all of these studies dealt with the study of the effect of the cavity ratio on heat transfer by free convection from square-shaped surfaces, which is the form that is more applied in electronic devices. Therefore, the current research means studying the rate of change in the average of Nusselt number, which represents a function of the rate of change in the rate of heat transfer by convection, as well as studying the thermal gradient above the surface, and this was done through using three hollow surfaces in proportions (0.25,0.5,0.75) of the total area.

An Evaporating Ethanol Meniscus—Part I: Experimental Studies

1979 ◽  
Vol 101 (1) ◽  
pp. 55-58 ◽  
Author(s):  
F. J. Renk ◽  
P. C. Wayner
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Capillary Flow ◽  
Experimental Studies ◽  
Resistance Thermometers ◽  
Flow Heat ◽  
Meniscus Profile

The profile of an evaporating ethanol meniscus was measured as a function of the evaporative heat flux using interferometry. A measure of the evaporative heat flux was obtained using vapor deposited resistance thermometers. The meniscus profile was found to be stable and a function of the heat flux for the heat flux range of 0 – 1.36w/m of interline. These results were used in an analysis of capillary flow heat transfer in Part II.

Heat Transfer Enhancement in a Tube Using Triangular Ribs

2008 ◽  
Author(s):  
Veysel Ozceyhan ◽  
Sibel Gunes
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Enhancement ◽  
External Surface ◽  
Numerical Study ◽  
Experimental Studies ◽  
Working Fluid ◽  
Uniform Heat Flux ◽  
Enhancement Ratio ◽  
Transfer Enhancement

A numerical study was undertaken for investigating the heat transfer enhancement in a tube with triangular cross sectioned ribs. The spacing between the ribs were kept constant as a distance of tube diameter, D. Three different rib thicknesses were considered for numerical analyses. Uniform heat flux was applied to the external surface of the tube and air was selected as working fluid. Numerical calculations were performed with FLUENT 6.1.22 code, in the range of Reynolds number 8000–36000. The results obtained from a smooth tube and rib inserted tube were compared with those from the experimental studies in literature in order to validate the numerical method. The variation of Nusselt number, friction factor and overall enhancement ratios for the tube with triangular cross sectioned ribs were presented. Consequently, a maximum gain of 1.34 on overall enhancement ratio is obtained for S/D = 0.75.

Simulation of the Heat Transfer in a Gas Turbine Combustor Fueled With Coal-Water Mixture: Part 2 — Model Predictions and Experimental Data

1986 ◽  
Author(s):  
Ihab H. Farag ◽  
Joseph L. Vaillancourt
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Flux ◽  
Gas Turbine ◽  
Transfer Rate ◽  
Water Mixture ◽  
Gas Turbine Combustor ◽  
Total Heat Transfer ◽  
Transfer Processes ◽  
Model Predictions

Data was obtained from the combustion of coal derived fuels in a 30 inch diameter, 4 foot long bench scale atmospheric unit fueled with CWF. The data is presented and compared with model predictions of ash, temperature, and mole fraction distributions. A computer model was developed to simulate the heat transfer processes taking place in a gas turbine combustor (GTC) burning a coal water fuel (CWF). It is to predict the species and temperature distribution, the heat flux patterns, and the contribution of both convection and radiation to the total heat transfer rate. This model was verified in part 1 of this paper.

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