Study of heat conduction in three-layered structure—a sandwich model

2020 ◽  
Vol 95 (4) ◽  
pp. 045222
Author(s):  
Tarika K Patel ◽  
P N Gajjar
2014 ◽  
Vol 1051 ◽  
pp. 823-827
Author(s):  
Ching Wu Wang ◽  
Ti Chun Yeh ◽  
Kai Chun Lin ◽  
Kuan Hsun Chen ◽  
Wei Chih Wang ◽  
...  

In various traditional technologies of solving the heat-dissipation problem for LED, all of these methods exhaust the waste heat into the environment and cause the more serious greenhouse effect. In this article, we present a new heat-dissipation method for high brightness 10W LED bulb using a novel structure of thermoelectric chip module. Evidence illustrates that graphite performs both the best heat-absorption material as well as the superior heat-dissipation material for LED thermoelectric chip module. Besides, the double-layered structure with graphite as heat-conduction material of LED thermoelectric module could create the most temperature-difference and thus conduct the highest output power. It implies that double-layered structure of LED thermoelectric chip module with graphite as heat-conduction material is the optimal structure for heat-dissipation of 10W LED bulb.


2018 ◽  
Author(s):  
Sean McInerney ◽  
Elliot J Carr ◽  
Matthew J Simpson

AbstractIn this work we consider a recent experimental data set describing heat conduction in living porcine tissues. Understanding this novel data set is important because porcine skin is similar to human skin. Improving our understanding of heat conduction in living skin is relevant to understanding burn injuries, which are common, painful and can require prolonged and expensive treatment. A key feature of skin is that it is layered, with different thermal properties in different layers. Since the experimental data set involves heat conduction in thin living tissues of anesthetised animals, an important experimental constraint is that the temperature within the living tissue is measured at one spatial location within the layered structure. Our aim is to determine whether this data is sufficient to reliably infer the heat conduction parameters in layered skin, and we use a simplified two-layer mathematical model of heat conduction to mimic the generation of experimental data. Using synthetic data generated at one location in the two-layer mathematical model, we explore whether it is possible to infer values of the thermal diffusivity in both layers. After this initial exploration, we then examine how our ability to infer the thermal diffusivities changes when we vary the location at which the experimental data is recorded, as well as considering the situation where we are able to monitor the temperature at two locations within the layered structure. Overall, we find that our ability to parameterise a model of heterogeneous heat conduction with limited experimental data is very sensitive to the location where data is collected. Our modelling results provide guidance about optimal experimental design that could be used to guide future experimental studies.NomenclatureA brief description of all variables used in the document are given in Table 1.Table 1:Variable nomenclature and description.


Author(s):  
Tai D. Nguyen ◽  
Ronald Gronsky ◽  
Jeffrey B. Kortright

Nanometer period Ru/C multilayers are one of the prime candidates for normal incident reflecting mirrors at wavelengths < 10 nm. Superior performance, which requires uniform layers and smooth interfaces, and high stability of the layered structure under thermal loadings are some of the demands in practical applications. Previous studies however show that the Ru layers in the 2 nm period Ru/C multilayer agglomerate upon moderate annealing, and the layered structure is no longer retained. This agglomeration and crystallization of the Ru layers upon annealing to form almost spherical crystallites is a result of the reduction of surface or interfacial energy from die amorphous high energy non-equilibrium state of the as-prepared sample dirough diffusive arrangements of the atoms. Proposed models for mechanism of thin film agglomeration include one analogous to Rayleigh instability, and grain boundary grooving in polycrystalline films. These models however are not necessarily appropriate to explain for the agglomeration in the sub-nanometer amorphous Ru layers in Ru/C multilayers. The Ru-C phase diagram shows a wide miscible gap, which indicates the preference of phase separation between these two materials and provides an additional driving force for agglomeration. In this paper, we study the evolution of the microstructures and layered structure via in-situ Transmission Electron Microscopy (TEM), and attempt to determine the order of occurence of agglomeration and crystallization in the Ru layers by observing the diffraction patterns.


1881 ◽  
Vol 11 (270supp) ◽  
pp. 4307-4307
Author(s):  
William Crookes
Keyword(s):  

Sign in / Sign up

Export Citation Format

Share Document