A141 Investigation of internal heat transfer by measurement of 2-D temperature distribution inside PMMA during flame spread

Radiant floor cooling systems are increasingly used in practice. The temperature distribution on the floor surface and inside the floor structure, especially the minimum and average temperature of floor surface, determines the thermal performance of radiant floor systems. A good temperature distribution of the floor structure is very important to prevent occupant discomfort and avoid possible condensation in summer cooling. In this study, based on the heat transfer model of the single-layer homogeneous floor structure when there is no internal heat radiation in the room, this paper proposes a heat transfer model of single-layer floor radiant cooling systems when the room has internal heat radiation. Using separation variable methods, an analytical solution was developed to estimate temperature distribution of typical radiant floor cooling systems with internal heat radiation, which can be used to calculate the minimum temperature and the average temperature of typical composite floor structure. The analytical solution was validated by experiments. The values of the measured experiments are in a good agreement with the calculations. The absolute error between the calculated and the measured floor surface temperatures was within 0.45°C. The maximum relative error was within 2.31%. Prove that this model can be accepted. The proposed method can be utilized to calculate the cooling capacity of a typical multi-layer composite floor and will be developed in the future study for design of a typical radiant floor cooling system.

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A split ring—disc electrode with internal heat transfer facilities

Electrochimica Acta ◽

10.1016/0013-4686(88)80013-6 ◽

1988 ◽

Vol 33 (2) ◽

pp. 265-269

Author(s):

M. Shirkhanzadeh ◽

V. Ashworth ◽

G.E. Thompson

Keyword(s):

Heat Transfer ◽

Internal Heat ◽

Disc Electrode ◽

Split Ring ◽

Internal Heat Transfer

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The Measurement of Full-Surface Internal Heat Transfer Coefficients for Turbine Airfoils Using a Non-Destructive Thermal Inertia Technique

Volume 3: Turbo Expo 2002, Parts A and B ◽

10.1115/gt2002-30199 ◽

2002 ◽

Cited By ~ 2

Author(s):

Nirm V. Nirmalan ◽

Ronald S. Bunker ◽

Carl R. Hedlung

Keyword(s):

Heat Transfer ◽

Heat Transfer Coefficient ◽

Transfer Coefficient ◽

External Surface ◽

Internal Heat ◽

Transfer Coefficients ◽

Heat Transfer Coefficients ◽

Turbine Airfoils ◽

Non Destructive ◽

Internal Heat Transfer

A new method has been developed and demonstrated for the non-destructive, quantitative assessment of internal heat transfer coefficient distributions of cooled metallic turbine airfoils. The technique employs the acquisition of full-surface external surface temperature data in response to a thermal transient induced by internal heating/cooling, in conjunction with knowledge of the part wall thickness and geometry, material properties, and internal fluid temperatures. An imaging Infrared camera system is used to record the complete time history of the external surface temperature response during a transient initiated by the introduction of a convecting fluid through the cooling circuit of the part. The transient data obtained is combined with the cooling fluid network model to provide the boundary conditions for a finite element model representing the complete part geometry. A simple 1D lumped thermal capacitance model for each local wall position is used to provide a first estimate of the internal surface heat transfer coefficient distribution. A 3D inverse transient conduction model of the part is then executed with updated internal heat transfer coefficients until convergence is reached with the experimentally measured external wall temperatures as a function of time. This new technique makes possible the accurate quantification of full-surface internal heat transfer coefficient distributions for prototype and production metallic airfoils in a totally non-destructive and non-intrusive manner. The technique is equally applicable to other material types and other cooled/heated components.

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Investigation of internal heat transfer in ejection refrigeration systems

International Journal of Refrigeration ◽

10.1016/j.ijrefrig.2013.11.016 ◽

2014 ◽

Vol 40 ◽

pp. 131-139 ◽

Cited By ~ 6

Author(s):

Dariusz Butrymowicz ◽

Kamil Śmierciew ◽

Jarosław Karwacki

Keyword(s):

Heat Transfer ◽

Internal Heat ◽

Internal Heat Transfer

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Overall Cooling Effectiveness Characteristic and Influence Mechanism on an Endwall With Film Cooling and Impingement

Volume 5A: Heat Transfer ◽

10.1115/gt2015-43069 ◽

2015 ◽

Cited By ~ 2

Author(s):

Mingfei Li ◽

Xueying Li ◽

Jing Ren ◽

Hongde Jiang

Keyword(s):

Heat Transfer ◽

Film Cooling ◽

Internal Heat ◽

Main Flow ◽

Cooling Effectiveness ◽

Film Cooling Effectiveness ◽

One Dimensional ◽

Influence Mechanism ◽

Endwall Cooling ◽

Internal Heat Transfer

The cooling system is required to ensure gas turbine can work at high temperature, which has exceeded the material limitation. An endwall cooling test rig was built up to conduct the endwall cooling research. A detailed work was done for analyzing characteristics of endwall heat transfer and discussing the multi-parameter influence mechanism of overall cooling effectiveness. The main flow side heat transfer coefficient, adiabatic film cooling effectiveness and overall cooling effectiveness were measured in the experiments. The effects of coolant mass flowrate ratio (MFR) were considered through the measurement. In order to analyze how each of the parameters works on overall cooling effectiveness, a one-dimensional correlation was developed. The results showed that obvious enhancement could be found in cooling effectiveness by increasing coolant MFR, and the film jet can be easily attached to the surface after the acceleration of the main flow in the nozzle channel. Comparing with film cooling effectiveness, overall cooling effectiveness distribution is more uniform, which is due to the influence of internal cooling. The verified one-dimensional analysis method showed that the improvement in film cooling would be most efficient to heighten overall cooling effectiveness. The improvement in film cooling would be more efficient when film cooling effectiveness is in high level than in low level. However, the enhancement of internal heat transfer is more efficient when internal heat transfer coefficient is low.

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Improved Pyrolysis Model of Polymer Materials under Windy Conditions

MATEC Web of Conferences ◽

10.1051/matecconf/201930306004 ◽

2019 ◽

Vol 303 ◽

pp. 06004

Author(s):

Lizhong Yang ◽

Dimeng Lai ◽

Yuan Zheng ◽

Fei Peng

Keyword(s):

Heat Transfer ◽

Absorption Coefficient ◽

Critical Mass ◽

Internal Heat ◽

Fire Risk ◽

Polymer Materials ◽

Critical Surface ◽

Pyrolysis Model ◽

Mass Flow Rates ◽

Internal Heat Transfer

The polymer materials are widely used in various occasions, of which polymethyl methacrylate(PMMA) is used in architectural transparent roofs, telephone booths, stairs, and their fire risk is getting more and more attention. The ignition conditions （critical surface temperatures and critical mass flow rates） of polymer materials have extensively researched, but their internal heat transfer studies have been relatively rare, especially in wind environments. Considering that internal heat transfer research is important for the heat transfer of multi-layer materials, the study of heat transfer inside materials is also worthy of attention. In this work, we found that in-depth absorption theory is more suitable for solid pyrolysis models under wind conditions. An absorption coefficient depends with temperature are assumed, and it fits better than the constant absorption coefficient. In addition, this work made some improvements to the ignition model by employing the theory of in-depth absorption.

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