The Experts below are selected from a list of 165912 Experts worldwide ranked by ideXlab platform
Tom E. Diller - One of the best experts on this subject based on the ideXlab platform.
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Heat Flux measurement
2015Co-Authors: Tom E. DillerAbstract:This chapter reviews the most useful current Heat Flux instrumentation, particularly Heat Flux gauges. It also briefly discusses the optical methods, but these are generally research methods that require sophisticated equipment and data processing techniques. General principles for the proper use of Heat Flux gauges are discussed first, followed by the details of specific gauges along with some of their typical applications. Three classifications of gauges are considered based on measured temperature difference over space, the temperature change with time, and the power dissipated at a maintained temperature. The measurement methods are also categorized according to the type of temperature measurement. The three common techniques are thermocouples, resistance temperature devices (RTDs), and optical. Finally, the chapter discusses the calibration of Heat Flux gauges along with error analysis. There are a number of problems and complications that should be taken into account while planning for any Heat Flux measurements. Keywords: calibration; error analysis; Heat Flux gauges; Heat Flux measurement; optical methods; resistance temperature devices (RTDs); thermocouples
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Heat Flux measurement
2013Co-Authors: Tom E. DillerAbstract:Owing to the importance of energy in modern society, Heat transfer (the movement of thermal energy) has become a crucial factor in many engineering systems. Measurements of Heat transfer are therefore important, but remain a challenge to accomplish with accuracy. Various commercial Heat Flux gages and research methods are available to measure Heat transfer in a wide range of applications. This chapter explores how to accurately and reliably measure Heat Flux (Heat transfer per area) with these techniques in practical situations. Keywords: calorimeter; calibration; differential thermocouple; energy transfer; frequency response; Heat Flux gage; response time; RTD; sensor; temperature; thermoelectric
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in situ high temperature Heat Flux sensor calibration
2010Co-Authors: Clayton A. Pullins, Tom E. DillerAbstract:Abstract Recent advances in Heat Flux measurement have resulted in the development of a robust thermopile Heat Flux sensor intended for use in extreme thermal environments. The High Temperature Heat Flux Sensor (HTHFS) is capable of simultaneously measuring thermopile surface temperature and Heat Flux at sensor temperatures up to 1000 °C. The need for high temperature Heat Flux calibration of the HTHFS has resulted in the development of a new wide angle radiation calibration system, which operates with the sensor at elevated temperatures. The temperature dependence of the sensor output over the range of 100–900 °C has been successfully characterized with acceptable uncertainty limits. The calibrated HTHFS sensitivity agrees well with a theoretical sensitivity model, suggesting that the primary cause for the sensor’s output temperature dependence is due to the change in thermal conductivity of the sensor elements with temperature.
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Durable Heat Flux Sensor for Extreme Temperature and Heat Flux Environments
2010Co-Authors: Andrew Gifford, Clayton A. Pullins, David O. Hubble, Scott T Huxtable, Tom E. DillerAbstract:This paper reports on the development and evaluation of a novel Heat Flux sensor, the high-temperature Heat Flux sensor, tested at temperatures and Heat Flux levels in excess of 1000°C and 10-13 W/cm 2 , respectively. The current sensor configuration uses type-K thermocouple materials in a durable welded thermopile arrangement contained within a surface-mountable high-temperature housing. The steady-state sensitivity of the design is predicted using a simplified one-dimensional thermal-resistance model. The design performance of a prototype sensor is validated using both conduction and convection Heat transfer calibration at low temperature. The average experimental values of the sensitivity are 623 ± 33 mV/W/cm 2 and 579 ± 29 mV/W/cm 2 in conduction and convection, respectively. These calibration results compare very well with the predicted room-temperature sensitivity of 559 μV/W/cm 2 . Minimal dependence on Heat transfer coefficient is found in convection. Prolonged thermal cycling of the sensor using a high-temperature kiln and a propane torch apparatus demonstrates survivability near the maximum temperature of the thermoelectric materials with negligible oxidation or loss of calibration.
Peter H Yoon - One of the best experts on this subject based on the ideXlab platform.
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nonlinear development of electron Heat Flux instability particle in cell simulation
2019Co-Authors: Sangyun Lee, E Lee, Peter H YoonAbstract:Finite Heat Flux often exists in space and astrophysical plasmas, which can be a free energy source for Heat Flux instability. The solar wind is a well-known example of such plasmas and a number of previous studies have investigated the characteristics of Heat Flux instability in the context of solar wind. In the literature there exists some uncertainties regarding the properties of Heat Flux instability. While some linear theories predict the association of the Heat Flux instability with right-hand polarized whistler waves, other studies argue for left-hand polarized unstable modes. The present study investigates the nonlinear development of initially unstable left-hand Heat Flux mode by means of particle-in-cell simulation. It is found that while the early phase is characterized by the left-hand polarization, in agreement with linear theory, as the wave amplitude becomes high and the instability enters the nonlinear phase, the dominant wave mode gradually switches over to the right-hand polarized waves. Such a behavior is related to the pitch angle scattering of the Heat Flux carrying electrons by nonlinear interaction with large-amplitude waves. The present study shows that the Heat Flux instability generally requires nonlinear treatment such that characterizing its behavior with linear theories may not always be adequate.
R D Saunders - One of the best experts on this subject based on the ideXlab platform.
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High-Heat-Flux sensor calibration using black-body radiation
2003Co-Authors: Annageri V. Murthy, Benjamin K. Tsai, R D SaundersAbstract:This paper deals with the radiative calibration aspects of high-Heat-Flux sensors using black-body radiation. In the last two years, several Heat-Flux sensors were calibrated up to 50 kW/m 2 using a 25 mm diameter aperture variable-temperature black body and a reference room-temperature electrical-substitution radiometer. Tests on a typical Schmidt-Boelter Heat-Flux sensor showed long-term repeatability of calibration is within 0.6%. Plans for extending the present calibration capability to 100 kW/m 2 are discussed.
Min Zhang - One of the best experts on this subject based on the ideXlab platform.
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Heat Flux investigations during flame thermal spray process using the lumped capacitance method
2017Co-Authors: Duo Yi, Min ZhangAbstract:Abstract The evaluation of Heat Flux is vital in the field of thermal spray process since it decides the temperature gradient, the formation of the residual stress inside the coating and finally affects the coating properties. Especially for the specific net incident Heat Flux density launched by the torch during each passage, it affects greatly the interaction between the previous and latter adjacent layers, the temperature gradient formation as well as the residual stress distribution along the vertical direction during the coating deposition process. This work mainly concentrates on the estimation of Heat Flux density during flame thermal spray process based on a lumped capacitance model. The Heat Flux evolution during one multi-pass of the torch was analyzed in detail and the average Heat Flux density impinging the substrate surface was firstly estimated, the root mean square error between the measured temperature and the numerical estimation was selected as the evaluation criteria to compare the calculation accuracy. The dynamic increase of coating mass was then added into consideration and the net incident Heat Flux density launched by the torch was estimated. The peak power value of the Heat Flux density was estimated based on an assumed Gaussian form of thermal energy distribution.
Zhang Min - One of the best experts on this subject based on the ideXlab platform.
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Heat Flux investigations during flame thermal spray process using the lumped capacitance method
2017Co-Authors: Yi Duo, Zhang MinAbstract:The evaluation of Heat Flux is vital in the field of thermal spray process since it decides the temperature gradient, the formation of the residual stress inside the coating and finally affects the coating properties. Especially for the specific net incident Heat Flux density launched by the torch during each passage, it affects greatly the interaction between the previous and latter adjacent layers, the temperature gradient formation as well as the residual stress distribution along the vertical direction during the coating deposition process. This work mainly concentrates on the estimation of Heat Flux density during flame thermal spray process based on a lumped capacitance model. The Heat Flux evolution during one multi-pass of the torch was analyzed in detail and the average Heat Flux density impinging the substrate surface was firstly estimated, the root mean square error between the measured temperature and the numerical estimation was selected as the evaluation criteria to compare the calculation accuracy. The dynamic increase of coating mass was then added into consideration and the net incident Heat Flux density launched by the torch was estimated. The peak power value of the Heat Flux density was estimated based on an assumed Gaussian form of thermal energy distribution. (C) 2017 Elsevier Ltd. All rights reserved.National Natural Science Foundation of China [61327812]SCI(E)ARTICLE554-56112
