Download or read book Experimental Performance of a Micromachined Heat Flux Sensor written by S. Stefanescu and published by . This book was released on 1998 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Steady-state and frequency response calibration of a microfabricated heat-flux sensor have been completed. This sensor is batch fabricated using standard, micromachining techniques, allowing both miniaturization and the ability to create arrays of sensors and their corresponding interconnects. Both high-frequency and spatial response is desired, so the sensors are both thin and of small cross-sectional area. Thin-film, temperature-sensitive resistors are used as the active gauge elements. Two sensor configurations are investigated: (1) a Wheatstone-bridge using four resistors; and (2) a simple, two-resistor design. In each design, one resistor (or pair) is covered by a thin layer (5000 A) thermal barrier; the other resistor (or pair) is covered by a thick (5 microns) thermal barrier. The active area of a single resistor is 360 microns by 360 microns; the total gauge area is 1.5 mm square. The resistors are made of 2000 A-thick metal; and the entire gauge is fabricated on a 25 microns-thick flexible, polyimide substrate. Heat flux through the surface changes the temperature of the resistors and produces a corresponding change in resistance. Sensors were calibrated using two radiation heat sources: (1) a furnace for steady-state, and (2) a light and chopper for frequency response.

Download or read book Experimental Performance of a Micromachined Heat Flux Sensor written by S. Stefanescu and published by . This book was released on 1998 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Steady-state and frequency response calibration of a microfabricated heat-flux sensor have been completed. This sensor is batch fabricated using standard, micromachining techniques, allowing both miniaturization and the ability to create arrays of sensors and their corresponding interconnects. Both high-frequency and spatial response is desired, so the sensors are both thin and of small cross-sectional area. Thin-film, temperature-sensitive resistors are used as the active gauge elements. Two sensor configurations are investigated: (1) a Wheatstone-bridge using four resistors; and (2) a simple, two-resistor design. In each design, one resistor (or pair) is covered by a thin layer (5000 A) thermal barrier; the other resistor (or pair) is covered by a thick (5 microns) thermal barrier. The active area of a single resistor is 360 microns by 360 microns; the total gauge area is 1.5 mm square. The resistors are made of 2000 A-thick metal; and the entire gauge is fabricated on a 25 microns-thick flexible, polyimide substrate. Heat flux through the surface changes the temperature of the resistors and produces a corresponding change in resistance. Sensors were calibrated using two radiation heat sources: (1) a furnace for steady-state, and (2) a light and chopper for frequency response.

Download or read book EXPERIMENTAL PERFORMANCE OF A MICROMACHINED HEAT FLUX SENSOR NASA TM 107517 AUG 6 1998 written by United States. National Aeronautics and Space Administration and published by . This book was released on 1999* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental Performance of a Heat Flux Microsensor written by J. M. Hager (Of Vatell Corp.) and published by . This book was released on 1990 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The performance characteristics of a heat flux microsensor have been measured and analyzed. This is a new heat flux gage system that is made using microfabrication techniques. The gages are small, have high frequency response, can measure very high heat flux, and output a voltage directly proportional to the heat flux. Each gage consists of a thin thermal resistance layer sandwiched between many thermocouple pairs forming a differential thermopile. Because the gage is made directly on the measurement surface and the total thickness is less than 2 micrometer, the presence of the gage contributes negligible flow and thermal disruption. The active surface area of the gage is 3 mm by 4 mm, with the leads attached outside this area to relay the surface heat flux and temperature signals. Gages were made and tested on glass and silicon substrates. The steady and unsteady response was measured experimentally and compared with analytical predictions. The analysis was performed using a one-dimensional, transient, finite-difference model of the six layers comprising the gage plus the substrate. Steady-state calibrations were done on a convection heat transfer apparatus and the transient response was measured to step changes of the imposed radiative flux. As an example of the potential capabilities, the time-resolved heat flux was measured at a stagnation point with imposed free-stream turbulence. A hot-film probe placed outside the boundary layer was used to provide a simultaneous signal showing the corresponding turbulent velocity fluctuations.

Download or read book Non contact Heat Flux Measurement Using a Transparent Sensor written by Daniel Ng and published by . This book was released on 1993 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book 33rd AIAA ASME SAE ASEE Joint Propulsion Conference Exhibit written by and published by . This book was released on 1997 with total page 598 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Monthly Catalog of United States Government Publications written by and published by . This book was released on 2000 with total page 658 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Heat Flux Sensor Applications for Below Grade Energy Studies written by PH. Shipp and published by . This book was released on 1985 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of heat flux sensors for energy studies of below-grade building envelopes and soil heat transfer is discussed. In a two-year study of three basements, heat flux sensors provided valuable information about local variations over the envelope surfaces. For complex building geometries, experimental designs that combine calorimetric monitoring of energy consumption with envelope heat flux profiles from heat flux sensors offer the most efficient means of determining building thermal performance.

Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 974 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development of Micro nano scale Sensors for Investigation of Heat Transfer in Multi phase Flows written by Sae Il Jeon and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this investigation was to develop micro/nano-scale temperature sensors for measuring surface temperature transients in multi-phase flows and heat transfer. Surface temperature fluctuations were measured on substrates exposed to phase change processes. Prior reports in the literature indicate that these miniature scale surface temperature fluctuations can result in 60-90% of the total heat flux during phase change heat transfer. In this study, DTS (Diode Temperature Sensors) were fabricated with a doping depth of ~100 nm on n-type silicon to measure the surface temperature transients on a substrate exposed to droplet impingement cooling. DTS are expected to have better sensor characteristics compared to TFTs (Thin Film Thermocouples), due to their small size and faster response (which comes at the expense of the smaller operating temperature range). Additional advantages of DTS include the availability of robust commercial micro fabrication processes (with diode and transistor node sizes currently in the size range of ~ 30 nm), and that only 2N wire leads can be used to interrogate a set of N x N array of sensors (in contrast thermocouples require 2 N x N wire leads for N x N sensor array). The DTS array was fabricated using conventional semi-conductor processes. The temperature response of the TFT and DTS was also calibrated using NIST standards. Transient temperature response of the DTS was recorded using droplet impingement cooling experiments. The droplet impingement cooling experiments were performed for two different test fluids (acetone and ethanol). An infrared camera was used to verify the surface temperature of the substrate and compare these measurements with the temperature values recorded by individual DTS. PVD (Physical Vapor Deposition) was used for obtaining the catalyst coatings for subsequent CNT synthesis using CVD (Chemical Vapor Deposition) as well as for fabricating the thin film thermocouple (TFT) arrays using the "lift-off" process. Flow boiling experiments were conducted for three different substrates. Flow boiling experiments on bare silicon wafer surface were treated as the control experiment, and the results were compared with that of CNT (Carbon Nano-Tube) coated silicon wafer surfaces. Similar experiments were also performed on a pure copper surface. In addition, experiments were performed using compact condensers. Micro-scale patterns fabricated on the refrigerant side of the compact heat exchanger were observed to cause significant enhancement of the condensation heat transfer coefficient.

Download or read book Microscale and Nanoscale Heat Transfer written by C.B. Sobhan and published by CRC Press. This book was released on 2008-06-12 with total page 317 pages. Available in PDF, EPUB and Kindle. Book excerpt: Through analyses, experimental results, and worked-out numerical examples, Microscale and Nanoscale Heat Transfer: Fundamentals and Engineering Applications explores the methods and observations of thermophysical phenomena in size-affected domains. Compiling the most relevant findings from the literature, along with results from their own re

Download or read book Aerospace America written by and published by . This book was released on 1997 with total page 654 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Analytical and Experimental Studies of Micromachined MEMS Flow Sensor written by Abhinav Kumar and published by . This book was released on 2006 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Microfluidics written by Stéphane Colin and published by John Wiley & Sons. This book was released on 2013-05-06 with total page 313 pages. Available in PDF, EPUB and Kindle. Book excerpt: The recent development of microscale technologies makes it possible to design complex microsystems devoted to transport, dosing, mixing, analysis or even synthesis of fluids. Applications are numerous and exist in almost every industrial field, from biotechnology and healthcare to aeronautics and advanced materials manufacturing. Microfluidics is a relatively new research area, usually comprising work with microsystems and involving internal fluid flows with characteristic dimensions of the order of one micrometer (1 x 10 -6 m). This book provides engineers and researchers with a range of tools for modeling, experimenting on, and simulating these microflows, as a preliminary step in designing and optimizing fluidic microsystems. The various consequences of miniaturization on the hydrodynamics of gas, liquid or two-phase flows, as well as on associated heat transfer phenonema, are analyzed. The book is illustrated with examples that demonstrate the wide diversity of applications, and the breadth of novel uses of these fluidic microsystems.

Download or read book Experimental and Computational Heat Transfer Analysis of Micro Channel Heat Sink with Different Manifold Arrangements written by Independently Published and published by . This book was released on 2018-09-14 with total page 69 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heat sink is an object, system or an environment that absorbs or dissipates heat from anotherusing direct or radiant thermal contact. Heat sink is object that enhances heat dissipation fromcomponent to a cooler ambient. The primary purpose of a heat sink is to maintain the temperatureof the device being cooled within acceptable limits as specified by the component manufacturer.Heat sinks are normally made up of copper or aluminum and is in directly contact with microchipson a circuit board.This advancement leads to the development of miniaturized systems, which further leads tovarious applications, as in the field of medical science, electronic and bioengineering. These typesof systems often contain small scale fluid channels embedded in the surrounding solids withheating sourcesStudy have been done on the different shapes of manifolds through the project. In this workdifferent watts (50, 75, 100 and 125 W) are used with Reynolds number ranging from 342 to857.Due to the instability of flow at the entrance and exit regions of the micro channels, it is thebasic needs to come up with an efficient design of inlet and outlet manifold shapes and with anefficient design of micro-channels.The overall performance of micro channel heat sink (MCHS) as a system is affected by the inletand outlet manifold arrangements in addition to array of micro channel. In the present study theexperimental analysis is performed w.r.t the heat transfer coefficient, pressure drop and Nusseltnumber for three different manifold arrangements. In the experiment deionized water is made toflow through the inlet manifolds to the array of micro channels and exit is through outletmanifolds. In the present work three different arrangements: Rectangular (R), Rectangle withsemi-circular (RSC) and Divergent Convergent (DC) of the inlet and outlet manifolds areselected. Within the Reynolds number range 342-857 DC type manifold has highest heat transfercoefficient of about 24%-32% in comparison to Rectangle (R) type manifold while Rectanglewith semi-circle (RSC) shows an enhancement of about 7% to 10% as compare to Rectangular(R).

Download or read book Performance and Modeling of Heat Flux Sensors in Different Environments written by D. G. Holmberg and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Testing of an Innovative Metal Nanothread Heat Flux Sensor written by Héctor Sánchez Vicente and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermal sensors are currently highly used in building applications to assess losses and determine possible thermal bridges. However, in some cases they are not useful enough because of the field conditions or, sometimes, due to the dimensions of the sensor. This thesis aims to calibrate and test a new product developed by JonDeTech AB company; a tiny heat flux - temperature sensor based on metal nanothreads and a vertical or "out-of-the-plane" thread arrangement. It may have a bright future in measuring local heat flux through building and installation components owing to its tininess. Three methods have been applied. First, calibration with a specific device designed for this purpose in a controlled environment. Second, field test measurements within an ongoing project by Gävle University in Gävle city hall historical building. And third, finite element simulations where the experimental scenarios were replicated. By these methods it was possible to apply corrections on the experimental procedures and make this work more accurate. It was also determined, the calibration curve of the sensor and a slight temperature dependency. In the field measurements, the output of the new heat flux sensor (using the calibration curves) was compared with output from a heat flux sensor available on the market. There is a good correspondence in the dynamics of the two sensors output, but there are discrepancies in the order of magnitude. Finite element simulations indicate that differences in the incidental direction of heat through the sensor are different in-situ and calibration, thus affecting results. Larger deviations are obtained for lower heat flux values (