scholarly journals Thermal Conductivity of Protein-Based Materials: A Review

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 456 ◽  
Author(s):  
Ye Xue ◽  
Samuel Lofland ◽  
Xiao Hu
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Polymer Materials ◽  
Protein Films ◽  
Processing Technologies ◽  
Fibrous Proteins ◽  
Chemical Residues ◽  
Fast Development ◽  
High Flexibility ◽  
Transfer Direction

Fibrous proteins such as silks have been used as textile and biomedical materials for decades due to their natural abundance, high flexibility, biocompatibility, and excellent mechanical properties. In addition, they also can avoid many problems related to traditional materials such as toxic chemical residues or brittleness. With the fast development of cutting-edge flexible materials and bioelectronics processing technologies, the market for biocompatible materials with extremely high or low thermal conductivity is growing rapidly. The thermal conductivity of protein films, which is usually on the order of 0.1 W/m·K, can be rather tunable as the value for stretched protein fibers can be substantially larger, outperforming that of many synthetic polymer materials. These findings indicate that the thermal conductivity and the heat transfer direction of protein-based materials can be finely controlled by manipulating their nano-scale structures. This review will focus on the structure of different fibrous proteins, such as silks, collagen and keratin, summarizing factors that can influence the thermal conductivity of protein-based materials and the different experimental methods used to measure their heat transfer properties.

The Solid-State Electrocaloric Refrigeration With Unimorph Beam and its Analytical Model

2018 ◽  
Author(s):  
Zhimin Sun ◽  
Qing-Ming Wang ◽  
William S. Slaughter
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Solid State ◽  
Temperature Change ◽  
Analytical Model ◽  
Step Motor ◽  
Ratio Requirement ◽  
Cooling Technology ◽  
Converse Piezoelectric Effect ◽  
Transfer Direction

Electrocaloric (EC) cooling technology, which has reversible temperature change of a polarizable material in an adiabatic condition with the application and/or removal of an electric field, exhibits some great advantages for efficient solid-state refrigeration. However, many challenges still exist in EC cooling technology. One of the main challenges is how to control the heat transfer direction. Some of the reported device types require movement of EC material by step motor or fluid media by pump back and forth between heat source and heat sink for controlling heat transfer direction. The other device designs utilize thermal diodes by adjusting their thermal conductivity to control heat transfer direction. Here we report a solid-state electrocaloric refrigeration using unimorph beam structure which has temperature change due to EC effect and bending behavior due to converse piezoelectric effect. The new device design can eliminate problems of fluid medium loss, friction, high thermal conductivity ratio requirement and external system assistance, etc., existed in the previously reported EC cooling device types. An analytical model is also derived by considering multi-physical phenomenon. The model shows that the temperature change is a combinatorial result from the couplings of thermal, electric and mechanical field in the device.

scholarly journals The Role of Carbonized Layers for Fire Protection of Polymer Materials

2018 ◽  
Vol 20 (1) ◽  
pp. 63
Author(s):  
Z.A. Mansurov ◽  
B.Ya. Kolesnikov ◽  
V.L. Efremov
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Oxidation ◽  
Epoxy Polymer ◽  
Burning Surface ◽  
Leading Edge ◽  
Polymer Materials ◽  
High Porosity ◽  
Flame Zone ◽  
Critical Temperatures

The present work studies the processes occurring in pre-flame zone in the form of «candle-like flame» which is spread over the surface of epoxy polymer. As exemplified by epoxy polymer, it can be seen that the dominating mechanism of heat transfer from flame to pre-flame zone of carbonized polymers is a thermal conductivity by condensed phase (to phase). The mechanism of gasification processes in pre-flame zone is proposed. Gasification of the material in front of the flame edge is a controlling process, and when selecting flame retardants, it is necessary to register their ability to influence on kinetics and mechanism of gasification. The flame leading edge is bordered with the surface of polymer, which largely determines the nature of heat transfer in pre-flame region. Due to investigations of gas-phase composition at «candle-like» combustion of epoxy polymer it has been detected a considerable amount of oxygen (up to 10‒12%) near burning surface. Its presence facilitates the thermal oxidation of polymer, moreover the rate of thermal oxidation can significantly exceed the thermal decomposition rate of the polymer. The possibility to form the heat-insulating intumescent layer during decomposition of carbonizable polymers was used at development of flame retardant coatings ‒ complex multicomponent systems. Which in turns forms the intumescent carbonized layer with high porosity and low thermal conductivity, and protects based material or construction from premature heating up to critical temperatures.

ALCOA QC-10

Alloy Digest ◽  
2009 ◽  
Vol 58 (7) ◽  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Aluminum Alloys ◽  
Physical Properties ◽  
Tensile Properties ◽  
Mold Material ◽  
Cast Products

Abstract Aluminum has long been accepted as a mold material. This alloy has a combination of faster machining, highest heat transfer, lighter weight, higher strength in thick sections, and greater thermal conductivity than other aluminum alloys. This datasheet provides information on physical properties, hardness, elasticity, and tensile properties. It also includes information on forming and machining. Filing Code: AL-423. Producer or source: Alcoa Forged and Cast Products.

Development of a New Correlation and Post Processing of Heat Transfer Coefficient and Pressure Drop of Functionalized COOH MWCNT Nanofluid by Artificial Neural Network

2018 ◽  
Vol 14 (2) ◽  
pp. 104-112 ◽  
Author(s):  
Mohammad Hemmat Esfe ◽  
Somchai Wongwises ◽  
Saeed Esfandeh ◽  
Ali Alirezaie
Keyword(s):  
Neural Network ◽  
Heat Transfer ◽  
Thermal Conductivity ◽  
Artificial Neural Network ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Regression Coefficient ◽  
New Correlation ◽  
The Neural Network

Background: Because of nanofluids applications in improvement of heat transfer rate in heating and cooling systems, many researchers have conducted various experiments to investigate nanofluid's characteristics more accurate. Thermal conductivity, electrical conductivity, and heat transfer are examples of these characteristics. Method: This paper presents a modeling and validation method of heat transfer coefficient and pressure drop of functionalized aqueous COOH MWCNT nanofluids by artificial neural network and proposing a new correlation. In the current experiment, the ANN input data has included the volume fraction and the Reynolds number and heat transfer coefficient and pressure drop considered as ANN outputs. Results: Comparing modeling results with proposed correlation proves that the empirical correlation is not able to accurately predict the experimental output results, and this is performed with a lot more accuracy by the neural network. The regression coefficient of neural network outputs was equal to 99.94% and 99.84%, respectively, for the data of relative heat transfer coefficient and relative pressure drop. The regression coefficient for the provided equation was also equal to 97.02% and 77.90%, respectively, for these two parameters, which indicates this equation operates much less precisely than the neural network. Conclusion: So, relative heat transfer coefficient and pressure drop of nanofluids can also be modeled and estimated by the neural network, in addition to the modeling of nanofluid’s thermal conductivity and viscosity executed by different scholars via neural networks.

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