Study on Thermal Performance for Straw Fiber Concrete Hollow Block

2014 ◽  
Vol 953-954 ◽  
pp. 1596-1599 ◽  
Author(s):  
Zu Peng Zhang ◽  
Shui Wen Zhu ◽  
Guo Ping Chen
Keyword(s):  
Thermal Conductivity ◽  
Temperature Distribution ◽  
Thermal Performance ◽  
Building Block ◽  
Plant Fiber ◽  
Coefficient Of Thermal Conductivity ◽  
Fiber Concrete ◽  
Hollow Block ◽  
Insulation Effect ◽  
The Mean

In this paper, based on ansys studies for thermal performance of concrete hollow block which were conducted on the content of 5% and 15% of the straw plant fiber, and get temperature distribution and the law of heat of the blocks which suffer the load of convection, then calculate the mean coefficient of thermal conductivity and thermal resistance based on the data block obtained. The results show that mixed plant fiber can effectively improve thermal performance for the concrete hollow block,and better insulation effect,thus can provide the basis for the promotion of plant fiber building block materials.

Stochastic Analysis of Temperature Distribution in a Solid With Random Heat Conductivity

1988 ◽  
Vol 110 (1) ◽  
pp. 23-29 ◽  
Author(s):  
Da Yu Tzou
Keyword(s):  
Thermal Conductivity ◽  
Temperature Distribution ◽  
Heat Conductivity ◽  
Stochastic Analysis ◽  
Solid Medium ◽  
Mean Value ◽  
Random Response ◽  
Thermal Failure ◽  
Numerical Examples ◽  
The Mean

Stochastic temperature distribution in a solid medium with random heat conductivity is investigated by the method of perturbation. The intrinsic randomness of the thermal conductivity k(x) is considered to be a distribution function with random amplitude in the solid, and several typical stochastic processes are considered in the numerical examples. The formulation used in the present analysis describes a situation that the statistical orders of the random response of the system are the same as those of the intrinsic random excitations, which is characteristic for the problem with extrinsic randomness. The maximum standard deviation of the temperature distribution from the mean value in the solid medium reveals the amount of unexpected energy experienced by the solid continuum, which should be carefully inspected in the thermal-failure design of structures with intrinsic randomness.

The Evaluation of the Simulation of Thermal Conductivity Coefficient Based on the Concrete with Minimum Thermal Resistance

2013 ◽  
Vol 448-453 ◽  
pp. 3320-3323
Author(s):  
Chao Zhao ◽  
Du Shun Ting
Keyword(s):  
Thermal Conductivity ◽  
Temperature Field ◽  
Thermal Resistance ◽  
Thermal Performance ◽  
Theoretical Basis ◽  
Thermal Conductivity Coefficient ◽  
Great Influence ◽  
Coefficient Of Thermal Conductivity ◽  
Primary Materials

The coefficient of thermal conductivity is one of the important parameters of concretes thermal performance and it has a relatively great influence on the temperature field inside its structure. This paper explores the basic equipments of the experiment on concretes coefficient of thermal conductivity and the requirements on configuration of primary materials. In the meanwhile, it studies the establishment of the model of concretes coefficient of thermal conductivity from the theoretical basis of thermal conductivity simulation, the division of thermal fluxs pathways and that of K in the formula of the coefficient of thermal conductivity.

scholarly journals Testing of property changes in recycled bedding for dairy cows

2016 ◽  
Vol 62 (Special Issue) ◽  
pp. S44-S52 ◽  
Author(s):  
J. Lendelová ◽  
M. Žitňák ◽  
M. Bošanský ◽  
M. Šimko ◽  
P. Piterka
Keyword(s):  
Thermal Conductivity ◽  
Dairy Cows ◽  
Thermal Performance ◽  
Dry Matter ◽  
Bedding Material ◽  
Coefficient Of Thermal Conductivity ◽  
Different Types ◽  
Property Changes

The aim of this study was to analyse the change of the characteristics of different types of organic bedding in deepened stall base cubicles for dairy cows. The research was carried out in barn 1 using separated raw manure solids, in barn 2 using drum composted manure solids and for comparison a barn 3 was chosen, which used traditional straw as a bedding material. Dry matter of separated raw manure and drum composted recycled manure solids in sample 1 collected after 2–3 hours of bedding acclimatization in the stable were lower (P < 0.05) compared with sample 3 collected 2–3 hours before the new bedding was spread, but dry matter of straw in sample 1 was higher (P < 0.05) compared with sample 3. The values of the coefficient of thermal conductivity show that the bedding from recycled sludge slurry is a good insulant and absorbent. In addition, a determined increase of humidity at the end of the bedding interval does not cause dramatic changes of thermal performance.

Maximizing Heat Transfer Through Joint Fin Systems

2005 ◽  
Vol 128 (2) ◽  
pp. 203-206 ◽  
Author(s):  
A.-R. A. Khaled
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Performance ◽  
Critical Length ◽  
The Other ◽  
Rigid Fixation ◽  
Convection Coefficient ◽  
Heat Transfer Characteristics ◽  
Cold Side ◽  
Transfer Characteristics

Heat transfer through joint fins is modeled and analyzed analytically in this work. The terminology “joint fin systems” is used to refer to extending surfaces that are exposed to two different convective media from its both ends. It is found that heat transfer through joint fins is maximized at certain critical lengths of each portion (the receiver fin portion which faces the hot side and the sender fin portion that faces the cold side of the convective media). The critical length of each portion of joint fins is increased as the convection coefficient of the other fin portion increases. At a certain value of the thermal conductivity of the sender fin portion, the critical length for the receiver fin portion may be reduced while heat transfer is maximized. This value depends on the convection coefficient for both fin portions. Thermal performance of joint fins is increased as both thermal conductivity of the sender fin portion or its convection coefficient increases. This work shows that the design of machine components such as bolts, screws, and others can be improved to achieve favorable heat transfer characteristics in addition to its main functions such as rigid fixation properties.

scholarly journals Enhancement of the Thermal Performance of the Paraffin-Based Microcapsules Intended for Textile Applications

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1120
Author(s):  
Virginija Skurkyte-Papieviene ◽  
Ausra Abraitiene ◽  
Audrone Sankauskaite ◽  
Vitalija Rubeziene ◽  
Julija Baltusnikaite-Guzaitiene
Keyword(s):  
Thermal Conductivity ◽  
Thermal Performance ◽  
Comparative Method ◽  
Multiwall Carbon Nanotubes ◽  
Acrylic Resin ◽  
Positive Influence ◽  
Outer Shell ◽  
Ir Camera ◽  
Spacer Fabric ◽  
Thermally Conductive

Phase changing materials (PCMs) microcapsules MPCM32D, consisting of a polymeric melamine-formaldehyde (MF) resin shell surrounding a paraffin core (melting point: 30–32 °C), have been modified by introducing thermally conductive additives on their outer shell surface. As additives, multiwall carbon nanotubes (MWCNTs) and poly (3,4-ethylenedioxyoxythiophene) poly (styrene sulphonate) (PEDOT: PSS) were used in different parts by weight (1 wt.%, 5 wt.%, and 10 wt.%). The main aim of this modification—to enhance the thermal performance of the microencapsulated PCMs intended for textile applications. The morphologic analysis of the newly formed coating of MWCNTs or PEDOT: PSS microcapsules shell was observed by SEM. The heat storage and release capacity were evaluated by changing microcapsules MPCM32D shell modification. In order to evaluate the influence of the modified MF outer shell on the thermal properties of paraffin PCM, a thermal conductivity coefficient (λ) of these unmodified and shell-modified microcapsules was also measured by the comparative method. Based on the identified optimal parameters of the thermal performance of the tested PCM microcapsules, a 3D warp-knitted spacer fabric from PET was treated with a composition containing 5 wt.% MWCNTs or 5 wt.% PEDOT: PSS shell-modified microcapsules MPCM32D and acrylic resin binder. To assess the dynamic thermal behaviour of the treated fabric samples, an IR heating source and IR camera were used. The fabric with 5 wt.% MWCNTs or 5 wt.% PEDOT: PSS in shell-modified paraffin microcapsules MPCM32D revealed much faster heating and significantly slower cooling compared to the fabric treated with the unmodified ones. The thermal conductivity of the investigated fabric samples with modified microcapsules MPCM32D has been improved in comparison to the fabric samples with unmodified ones. That confirms the positive influence of using thermally conductive enhancing additives for the heat transfer rate within the textile sample containing these modified paraffin PCM microcapsules.

scholarly journals Ballistic Heat Transport in Nanocomposite: The Role of the Shape and Interconnection of Nanoinclusions

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1982
Author(s):  
Paul Desmarchelier ◽  
Alice Carré ◽  
Konstantinos Termentzidis ◽  
Anne Tanguy
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Free Path ◽  
Mean Free Path ◽  
Strong Increase ◽  
Moderate Increase ◽  
Energy Propagation ◽  
The Mean ◽  
Dynamics Simulations

In this article, the effect on the vibrational and thermal properties of gradually interconnected nanoinclusions embedded in an amorphous silicon matrix is studied using molecular dynamics simulations. The nanoinclusion arrangement ranges from an aligned sphere array to an interconnected mesh of nanowires. Wave-packet simulations scanning different polarizations and frequencies reveal that the interconnection of the nanoinclusions at constant volume fraction induces a strong increase of the mean free path of high frequency phonons, but does not affect the energy diffusivity. The mean free path and energy diffusivity are then used to estimate the thermal conductivity, showing an enhancement of the effective thermal conductivity due to the existence of crystalline structural interconnections. This enhancement is dominated by the ballistic transport of phonons. Equilibrium molecular dynamics simulations confirm the tendency, although less markedly. This leads to the observation that coherent energy propagation with a moderate increase of the thermal conductivity is possible. These findings could be useful for energy harvesting applications, thermal management or for mechanical information processing.

Experiments on the flow of heat in liquid helium below 0.7 °K

1958 ◽  
Vol 246 (1246) ◽  
pp. 390-405 ◽  
Keyword(s):  
Thermal Conductivity ◽  
Liquid Helium ◽  
Free Path ◽  
Empirical Relation ◽  
Mean Free Path ◽  
Series Of Experiments ◽  
The Mean ◽  
Set Up ◽  
Low Pressures ◽  
Measured Thermal Conductivity

A series of experiments has been performed to study the steady flow of heat in liquid helium in tubes of diameter 0.05 to 1.0 cm at temperatures between 0.25 and 0.7 °K. The results are interpreted in terms of the flow of a gas of phonons, in which the mean free path λ varies with temperature, and may be either greater or less than the diameter of the tube d . When λ ≫ d the flow is limited by the scattering of the phonons at the walls, and the effect of the surface has been studied, but when λ ≪ d viscous flow is set up in which the measured thermal conductivity is increased above that for wall scattering. This behaviour is very similar to that observed in the flow of gases at low pressures, and by applying kinetic theory to the problem it can be shown that the mean free path of the phonons characterizing viscosity can be expressed by the empirical relation λ = 3.8 x 10 -3 T -4.3 cm. This result is inconsistent with the temperature dependence of λ as T -9 predicted theoretically by Landau & Khalatnikov (1949).

Sign in / Sign up

Export Citation Format

Share Document