A Coupled Methodology for Modeling the Transient Thermal Response of SI Engines Subject to Time-Varying Operating Conditions

1997 ◽  
Author(s):  
Douglas M. Baker ◽  
Dennis N. Assanis
Keyword(s):  
Thermal Response ◽  
Operating Conditions ◽  
Time Varying ◽  
Si Engines ◽  
Transient Thermal ◽  
Transient Thermal Response

Transient Thermal Response of Servers Through Air Temperature Measurements

2013 ◽  
Author(s):  
Hamza Salih Erden ◽  
H. Ezzat Khalifa ◽  
Roger R. Schmidt
Keyword(s):  
Thermal Conductance ◽  
Thermal Characteristics ◽  
Thermal Response ◽  
Operating Conditions ◽  
Cfd Analysis ◽  
Capacitance Measurements ◽  
Thermal Capacitance ◽  
Transient Thermal ◽  
Transient Thermal Response ◽  
Unsteady Conditions

Transient CFD analysis of data centers requires appropriate representations of the transient thermal characteristics of servers. Thermal conductance and thermal capacitance are two determining characteristics for the response of servers under unsteady conditions. Previous studies proposed tests that require detailed temperature and thermal capacitance measurements for each of the server component, requiring access to individual components inside the server. In this paper, we propose a method for obtaining the transient thermal characteristics of a server from server inlet and outlet temperatures under transient operating conditions.

Two centuries of the thermal regenerator

2000 ◽  
Vol 214 (1) ◽  
pp. 269-288 ◽  
Author(s):  
A. J. Organ
Keyword(s):  
Thermal Response ◽  
Original Description ◽  
Thermal Capacity ◽  
Operating Conditions ◽  
Temperature History ◽  
Elementary Transformation ◽  
Fluid Temperature ◽  
Transient Thermal ◽  
Transient Thermal Response ◽  
Flow Reversals

The paper looks back over almost 200 years taken to convert Stirling's original description of the thermal regenerator into a quantitative picture of transient thermal response. The ‘regenerator problem’ is found to be essentially the conjugate heat exchange problem by another name, and thus the subject of a massive literature, none of which, however, has, until recently, successfully addressed the problem of repeated flow reversals at low flush ratios. The gap in the repertoire is ironic, given that these are precisely the operating conditions of Stirling's original invention. An elementary transformation overcomes the difficulty of solving for any number of flow reversals at any flush ratio. Temperature-time histories are presented for the ‘classic’ problem with fixed entry temperatures. For sufficiently high thermal capacity ratio a straightforward and explicit solution emerges for fluid temperature history at cyclic steady state. The approach is shown to be sufficiently versatile to permit extension to the complex cyclic operating conditions of Stirling coolers and prime movers. Along the way it is noted that heat transfer correlations ( NSt N2/3Pr versus NRe) for wire gauzes frequently thought inapplicable to the regenerator by virtue of a supposed ‘steady flow’ connotation in fact owe their very existence to an early part-solution of transient thermal response. To this extent the correlations are the proper data to use.

Influence of Phonon Dispersion on Transient Thermal Response of Silicon-on-Insulator Transistors Under Self-Heating Conditions

2006 ◽  
Vol 129 (7) ◽  
pp. 790-797 ◽  
Author(s):  
Rodrigo A. Escobar ◽  
Cristina H. Amon
Keyword(s):  
Computational Models ◽  
Phonon Dispersion ◽  
Thermal Response ◽  
Domain Size ◽  
Phonon Transport ◽  
Silicon On Insulator ◽  
Nonlinear Relation ◽  
Temperature Levels ◽  
Transient Thermal ◽  
Transient Thermal Response

Lattice Boltzmann method (LBM) simulations of phonon transport are performed in one-dimensional (1D) and 2D computational models of a silicon-on-insulator transistor, in order to investigate its transient thermal response under Joule heating conditions, which cause a nonequilibrium region of high temperature known as a hotspot. Predictions from Fourier diffusion are compared to those from a gray LBM based on the Debye assumption, and from a dispersion LBM which incorporates nonlinear dispersion for all phonon branches, including explicit treatment of optical phonons without simplifying assumptions. The simulations cover the effects of hotspot size and heat pulse duration, considering a frequency-dependent heat source term. Results indicate that, for both models, a transition from a Fourier diffusion regime to a ballistic phonon transport regime occurs as the hotspot size is decreased to tens of nanometers. The transition is characterized by the appearance of boundary effects, as well as by the propagation of thermal energy in the form of multiple, superimposed phonon waves. Additionally, hotspot peak temperature levels predicted by the dispersion LBM are found to be higher than those from Fourier diffusion predictions, displaying a nonlinear relation to hotspot size, for a given, fixed, domain size.

Transient thermal response in ultrasonic additive manufacturing of aluminum 3003

2011 ◽  
Vol 17 (5) ◽  
pp. 369-379 ◽  
Author(s):  
David Schick ◽  
Sudarsanam Suresh Babu ◽  
Daniel R. Foster ◽  
Marcelo Dapino ◽  
Matt Short ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Thermal Response ◽  
Ultrasonic Additive Manufacturing ◽  
Transient Thermal ◽  
Transient Thermal Response

Transient Thermal Response of the Media by Free Space Laser Heating in Heat Assisted Magnetic Recording

2016 ◽  
Author(s):  
Shaomin Xiong ◽  
Robert Smith ◽  
Na Wang ◽  
Dongbo Li ◽  
Erhard Schreck ◽  
...  
Keyword(s):  
Magnetic Recording ◽  
Heat Conduction Problem ◽  
Temperature Response ◽  
Thermal Response ◽  
Areal Density ◽  
Heat Assisted Magnetic Recording ◽  
Lumped Model ◽  
The Media ◽  
Transient Thermal ◽  
Transient Thermal Response

Heat assisted magnetic recording (HAMR) promises to deliver higher storage areal density than the current perpendicular magnetic recording (PMR) product. A laser is introduced to the HAMR system to heat the high coercively magnetic media above the Curie temperature (Tc) which is as high as 750 K in order to enable magnetic writing. The thermal response of the media becomes very critical for the success of the data writing process. In this paper, a new method is proposed to understand the transient thermal behavior of the HAMR media. The temperature response of the media is measured based on thermal erasure of the magnetically written signal. A lumped model is built to simplify the heat conduction problem to understand the transient thermal response. Finite element modeling (FEM) is implemented to simulate the transient thermal response of the media due to the laser pulse heating. The experimental and simulation results show fairly good agreement.

Measurement of Thermal Conductivity of a Flexible Substrate

2014 ◽  
Author(s):  
Vivek Vishwakarma ◽  
Ankur Jain
Keyword(s):  
Thermal Conductivity ◽  
Analytical Model ◽  
Flexible Substrate ◽  
Thermal Response ◽  
Experimental Methodology ◽  
Plastic Substrate ◽  
The Past ◽  
Thin Plastic ◽  
Transient Thermal ◽  
Transient Thermal Response

A number of past papers have described experimental techniques for measurement of thermal conductivity of substrates and thin films of technological interest. Nearly all substrates measured in the past are rigid. There is a lack of papers that report measurements on a flexible substrate such as thin plastic. The paper presents an experimental methodology to deposit a thin film microheater device on a plastic substrate. This device, comprising a microheater line and a temperature sensor line is used to measure the thermal conductivity of the plastic substrate using the transient thermal response of the plastic substrate to a heating current. An analytical model describing this thermal response is presented. Thermal conductivity of the plastic substrate is determined by comparison of experimental data with the analytical model. Results described in this paper may aid in development of an understanding of thermal transport in flexible substrates.

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