THERMAL CONDUCTIVITY OF COMPOSITE POLYPROPYLENE/CARBON NANOFIBRES

2019 ◽  
Vol 1 (7) ◽  
pp. 72-76
Author(s):  
A. S. Stepashkina ◽  
M. Yu. Egorov ◽  
R. N. Tselms ◽  
T. P. Mishura
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Transfer Process ◽  
Heat Removal ◽  
Heat Transfer Process ◽  
Polymer Composite Material ◽  
Heat Conducting ◽  
Carbon Nanofibres ◽  
Linear Character ◽  
Filler Mass

The polymer composite material based on polypropylene (PP) matrix and vapor grown carbon fibers (VGCF) as filler was received by the melt-technology. Dependences of the thermal conductivity on the filler mass fraction and temperature were experimentally obtained. Such dependences have a nearly linear character. It is shown that the material heat-conducting properties don’t depend on the sample geometry. It is found out that in case the concentration of VGCF is more than 5% the material can be used for heat removal in electrical and electronic devices. To describe the heat transfer process a model was built based on the multichannel conduction problem. It allows describing the heat transfer process in composite materials with sharply differing heat-conducting properties of the components taking into account such material characteristics as density, heat capacity, heat conduction, and heat flow velocity.

scholarly journals Thermal conductivity and deformation of Taxodium hybrid ‘Zhongshanshan’ during heat transfer process

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 2645-2655
Author(s):  
Yuehua Zhu ◽  
Yaoli Zhang ◽  
Biao Pan
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Moisture Content ◽  
Transfer Process ◽  
Dimensional Change ◽  
Testing Temperature ◽  
Scientific Basis ◽  
Heat Transfer Process ◽  
Wood Moisture Content ◽  
Wood Moisture

The thermal conductivity and the deformation of wood from the Taxodium hybrid ‘Zhongshanshan’ were studied in the process of heat transfer. The results showed that the average thermal conductivity of this wood was 0.1257 W/(m·K) under the condition of 12% wood moisture content and 30 °C heat transfer temperature. When the testing temperature exceeded 0 °C, the thermal conductivity increased linearly with both temperature and wood moisture content and was affected by the moisture content of the wood. During the heat transfer process, the deformation of features caused repeated swelling and shrinkage in the longitudinal, radial, and tangential directions. The dimensional change was greatly affected by the wood’s moisture content and was less affected by the temperature. These results are of great meaning for the study of the heat transfer process of Taxodium hybrid ‘Zhongshanshan’ wood. Furthermore, it provides a scientific basis for the heat preservation effect, drying treatment, and pyrolysis treatment of Taxodium hybrid ‘Zhongshanshan’ wood for use as a building material.

An alternative criterion in heat transfer optimization

2010 ◽  
Vol 467 (2128) ◽  
pp. 1012-1028 ◽  
Author(s):  
Qun Chen ◽  
Hongye Zhu ◽  
Ning Pan ◽  
Zeng-Yuan Guo
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Entropy Generation ◽  
Transfer Process ◽  
Heat Transfer Process ◽  
Optimization Criterion ◽  
Entransy Dissipation ◽  
Minimum Entropy ◽  
Fourier’S Law ◽  
Fourier's Law

Entropy generation is recognized as a common measurement of the irreversibility in diverse processes, and entropy generation minimization has thus been used as the criterion for optimizing various heat transfer cases. To examine the validity of such entropy-based irreversibility measurement and its use as the optimization criterion in heat transfer, both the conserved and non-conservative quantities during a heat transfer process are analysed. A couple of irreversibility measurements, including the newly defined concept entransy , in heat transfer process are discussed according to different objectives. It is demonstrated that although thermal energy is conserved, the accompanied system entransy and entropy in heat transfer process are non-conserved quantities. When the objective of a heat transfer is for heating or cooling, the irreversibility should be measured by the entransy dissipation, whereas for heat-work conversion, the irreversibility should be described by the entropy generation. Next, in Fourier’s Law derivation using the principle of minimum entropy production, the thermal conductivity turns out to be inversely proportional to the square of temperature. Whereas, by using the minimum entransy dissipation principle, Fourier’s Law with a constant thermal conductivity as expected is derived, suggesting that the entransy dissipation is a preferable irreversibility measurement for heat transfer.

A Numerical Research on the Heat Transfer Process for a General Passive Heat Removal System

2017 ◽  
Author(s):  
Li Wei ◽  
Liu Zhuo ◽  
Guo Qiang ◽  
Yuan Yidan
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Transfer Process ◽  
Heat Removal ◽  
Heat Transfer Process ◽  
Sensitivity Analyses ◽  
Scaling Analysis ◽  
Water Tank ◽  
Heat Removal System ◽  
Removal System

A code module for simulating a general passive heat removal system composed of an elevated water tank, a heat exchanger and pipes connecting them is developed in this paper. Then, a typical heat transfer process in this heat removal system is calculated. According to the simulation results, the flash shows the most important impact of the heat transfer process for this passive heat removal system, especially the moment of the flash appearing. In order to design a scaled-down facility with the help of a scaling method to carry out experimental studies on the heat transfer process occurring in a PHRS for developing a more efficient heat removal system, all influence factors of flash should be conducted before a scaling analysis to make a good understanding for the flash. Finally, we get some qualitative conclusions based on sensitivity analyses for some influence parameters: 1) water temperature in the water tank, system flow resistance and the length of the outlet pipe should be ensured by designing according to scaling criteria strictly; 2) choosing a heat exchanger with geometric and material similarity can realize a consistency of heat transfer efficiency and 3) the liquid level in the water tank is less important.

scholarly journals Thermal conductivity, viscosity and heat transfer process in nanofluids: A critical review

2020 ◽  
Vol 2 (5) ◽  
pp. 175-192
Author(s):  
Saeed Noorzadeh ◽  
Farhad Sadegh Moghanlou ◽  
Mohammad Vajdi ◽  
Mohammad Ataei
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Transfer Process ◽  
Critical Review ◽  
Heat Transfer Process

Design of the Blast Furnace Wall Structure Made of Efficient Materials. Part 4. Calculation Examples

2020 ◽  
Vol 786 (11) ◽  
pp. 30-34
Author(s):  
A.M. IBRAGIMOV ◽  
◽  
L.Yu. GNEDINA ◽  
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Blast Furnace ◽  
Boundary Value Problems ◽  
Transfer Process ◽  
Rational Design ◽  
Boundary Value ◽  
Heat Transfer Process ◽  
Furnace Wall ◽  
Time Interval

This work is part of a series of articles under the general title The structural design of the blast furnace wall from efficient materials [1–3]. In part 1, Problem statement and calculation prerequisites, typical multilayer enclosing structures of a blast furnace are considered. The layers that make up these structures are described. The main attention is paid to the lining layer. The process of iron smelting and temperature conditions in the characteristic layers of the internal environment of the furnace is briefly described. Based on the theory of A.V. Lykov, the initial equations describing the interrelated transfer of heat and mass in a solid are analyzed in relation to the task – an adequate description of the processes for the purpose of further rational design of the multilayer enclosing structure of the blast furnace. A priori the enclosing structure is considered from a mathematical point of view as the unlimited plate. In part 2, Solving boundary value problems of heat transfer, boundary value problems of heat transfer in individual layers of a structure with different boundary conditions are considered, their solutions, which are basic when developing a mathematical model of a non-stationary heat transfer process in a multi-layer enclosing structure, are given. Part 3 presents a mathematical model of the heat transfer process in the enclosing structure and an algorithm for its implementation. The proposed mathematical model makes it possible to solve a large number of problems. Part 4 presents a number of examples of calculating the heat transfer process in a multilayer blast furnace enclosing structure. The results obtained correlate with the results obtained by other authors, this makes it possible to conclude that the new mathematical model is suitable for solving the problem of rational design of the enclosing structure, as well as to simulate situations that occur at any time interval of operation of the blast furnace enclosure.

Numerical Simulation for Microconvection Around Nano-Particle With Brownian Motion in Liquid

2003 ◽  
Author(s):  
B. X. Wang ◽  
H. Li ◽  
X. F. Peng ◽  
L. X. Yang
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Brownian Motion ◽  
Numerical Model ◽  
Temperature Gradient ◽  
Transfer Process ◽  
Heat Transfer Process ◽  
Nano Particles ◽  
Analytic Method ◽  
Nano Particle

The development of a numerical model for analyzing the effect of the nano-particles’ Brownian motion on the heat transfer is described. By using the Maxwell velocity distribution relations to calculate the most possible velocity of fluid molecules at certain temperature gradient location around the nano-particle, the interaction between fluid molecules and one single nano-particle is analyzed and calculated. Based on this, a syntonic system is proposed and the coupled effect that Brownian motion of nano-particles has on fluid molecules is simulated. This is used to formulate a reasonable analytic method, facilitating laboratory study. The results provide the essential features of the heat transfer process, contributed by micro-convection to be considered.

The 3-D Numerical Simulation of Heat Transfer Process of Finned Copper Tube

2011 ◽  
Vol 393-395 ◽  
pp. 412-415
Author(s):  
Jian Hua Zhong ◽  
Li Ming Jiang ◽  
Kai Feng
Keyword(s):  
Heat Transfer ◽  
Transfer Process ◽  
Theoretical Calculations ◽  
Structural Parameters ◽  
Convection Heat Transfer ◽  
Heat Transfer Process ◽  
Finned Tube ◽  
Copper Tube ◽  
Central Air Conditioning ◽  
Fin Thickness

In this article, finned copper tube used in the central air conditioning was acted as the discussed object. According to the combination with actual processing and theoretical calculations, Five finned tube was selected with typical structural parameters, and established their entity model using Pro/E, then the heat transfer process of finned tube was simulated through the ANSYS, the effect of the fin height, fin thickness and other structure parameters to the heat transfer enhancement of finned tube was researched. Meantime the efficiency of the heat transfer under different convection heat transfer coefficient was also studied.

Numerical Study on the Effect of Inner Tube Position on Heat Transfer Process in Self-Recuperative Radiant Tube

2011 ◽  
Vol 228-229 ◽  
pp. 676-680 ◽  
Author(s):  
Ye Tian ◽  
Xun Liang Liu ◽  
Zhi Wen
Keyword(s):  
Heat Transfer ◽  
Transfer Process ◽  
Numerical Study ◽  
Flame Temperature ◽  
Three Dimensional ◽  
Mathematic Model ◽  
Heat Transfer Process ◽  
Bulk Temperature ◽  
Radiant Tube ◽  
Peak Value

A three-dimensional mathematic model is developed for a 100kw single-end recuperative radiant tube and the simulation is performed with the CFD software FLUENT. Also it is used to investigate the effect of distance between combustion chamber exit and inner tube on heat transfer process. The results suggest that the peak value of combustion flame temperature drops along with the increasing of distance, which leads to low NOX discharging. Also radiant tube surface bulk temperature decreases, which causes radiant tube heating performance losses.

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