scholarly journals Comparison of Properties for Selected Experimental Set-Ups Dedicated to Measuring Thermal Parameters of Power LEDs

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3240
Author(s):  
Krzysztof Górecki ◽  
Przemysław Ptak ◽  
Marcin Janicki ◽  
Małgorzata Napieralska
Keyword(s):  
Optical Power ◽  
Measurement Procedure ◽  
Thermal Parameters ◽  
Measurement Results ◽  
Set Up ◽  
Transient Thermal

This article compares properties of two measurement set-ups dedicated to determining thermal parameters of power LEDs. The standard T3Ster set-up and the custom set-up developed in Gdynia Maritime University are considered. Both set-ups are described and the used measurement procedure is presented. The manner of measurement of optical power of the tested LEDs is also described. The method of measuring transfer transient thermal impedances between thermally coupled power LEDs using both set-ups is proposed. The measurement results of the mentioned parameters obtained with these set-ups for selected power LEDs are compared and discussed. Certain properties of software operating with both the considered measuring set-ups are also analyzed.

scholarly journals Influence of a Thermal Pad on Selected Parameters of Power LEDs

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3732
Author(s):  
Krzysztof Górecki ◽  
Przemysław Ptak ◽  
Tomasz Torzewicz ◽  
Marcin Janicki
Keyword(s):  
Optical Properties ◽  
Thermal Resistance ◽  
Optical Power ◽  
Junction Temperature ◽  
Operating Parameters ◽  
Cold Plate ◽  
Optical Efficiency ◽  
Forward Current ◽  
Measurement Results ◽  
Set Up

This paper is devoted to the analysis of the influence of thermal pads on electric, optical, and thermal parameters of power LEDs. Measurements of parameters, such as thermal resistance, optical efficiency, and optical power, were performed for selected types of power LEDs operating with a thermal pad and without it at different values of the diode forward current and temperature of the cold plate. First, the measurement set-up used in the paper is described in detail. Then, the measurement results obtained for both considered manners of power LED assembly are compared. Some characteristics that illustrate the influence of forward current and temperature of the cold plate on electric, thermal, and optical properties of the tested devices are presented and discussed. It is shown that the use of the thermal pad makes it possible to achieve more advantageous values of operating parameters of the considered semiconductor devices at lower values of their junction temperature, which guarantees an increase in their lifetime.

scholarly journals Selected Problems of Power MOSFETs Thermal Parameters Measurements

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8353
Author(s):  
Krzysztof Górecki ◽  
Krzysztof Posobkiewicz
Keyword(s):  
Measurement Error ◽  
Measurement Methods ◽  
Thermal Parameters ◽  
Contact Method ◽  
Electrical Method ◽  
Power Mosfets ◽  
Measurement Results ◽  
Additional Influence ◽  
Transient Thermal ◽  
Selection Of

In the paper, selected problems that are related to the measurements of thermal parameters of power MOSFETs that are placed on a common heat sink are analysed. The application of the indirect electrical method, the contact method, and the optical method in measuring self and mutual transient thermal impedances of these transistors is presented. The circuits that are required to perform measurements are presented and described. The errors of measurements are assessed for each of the considered methods. In the case of the indirect electrical method, an additional influence of the selection of a thermo-sensitive parameter and the function approximating thermometric characteristics on the measurement error are taken into consideration. The measurement results of the thermal parameters of the investigated transistors that were obtained using the considered measurement methods in various supply conditions are presented and discussed.

Numerical and Experimental Investigations of the Transient Thermal Behavior of a Steam By-Pass Valve at Steam Temperatures Beyond 700 °C

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Anis Haj Ayed ◽  
Martin Kemper ◽  
Karsten Kusterer ◽  
Hailu Tadesse ◽  
Manfred Wirsum ◽  
...  
Keyword(s):  
Thermal Behavior ◽  
Power Plants ◽  
Numerical Approach ◽  
Life Assessment ◽  
Experimental Investigations ◽  
Steam Power ◽  
Steam Power Plants ◽  
Cyclic Operation ◽  
Measurement Results ◽  
Transient Thermal

Increasing the efficiency of steam power plants is important to reduce their CO2 emissions and can be achieved by increasing steam temperatures beyond 700 °C. Within the present study, the thermal behavior of a steam by-pass valve subject to cyclic operation with 700 °C steam is investigated experimentally and numerically. An innovative numerical approach was applied to predict the valve’s thermal behavior during cyclic operation, which is essential for fatigue life assessment of such a component. Validation of the applied numerical approach has shown good agreement with measurement results, indicating the potential of its application for the valve design process.

scholarly journals Macrobending Loss Analysis on Singlemode-Multimode-Singlemode Fiber Optic Core

2019 ◽  
Vol 9 (2) ◽  
pp. 11-15
Author(s):  
Sisca Arisya Harry Andhina
Keyword(s):  
Light Source ◽  
Optical Fibers ◽  
Fiber Optic ◽  
Optical Power ◽  
Single Mode ◽  
Fiber Optic Cable ◽  
Power Meter ◽  
Loss Analysis ◽  
Measurement Results ◽  
Source Test

Macrobending often occurs in optical fibers that embedded in the ground due to shifting of soil or rocks in the ground causing interference in transmission. In this study used single-mode-multimode-singlemode fiber optic cable connected manually and axially measured using a light source test equipment and optical power meter and the results will be compared. The measurement results obtained the greater  value of macrobending losses with the smaller the diameter of the winding, and the greater the number of turns. The highest value of macrobending losses in multimode cables is -1.48dB at 0.5cm diameter with 5 turns, highest value of macrobending losses on single mode cables is -12.73dB at 0.5cm diameter with 5 turns,  lowest value of macrobending losses for multimode cables is -0.44dB at 5cm diameter with 1 twist, lowest macrobending losses in singlemode cables is -1.69dB at 5cm diameter with 1 twist. While the value of macrobending losses on axially connected SMS cables shows the highest value of macrobending losses on multimode cables is -1.12dB in diameter of 0.5cm with 5 turns,  highest value of macrobending losses on singlemode cables is -1.18dB at diameter of 0.5cm with 5 turns,  lowest value for macrobending losses on multimode cables is -0.66dB at 5cm in diameter with 1 twist, the smallest value for macrobending losses on singlemode cables is -0.27dB at 5cm diameter with 1 twist . The measurement results also showed that the macrobending losses of manually connected SMS cables were greater than the macrobending losses of axially connected SMS cables.

Measurement on Temperature Distribution of Metal Powder Stream in Laser Fabricating

2011 ◽  
Vol 101-102 ◽  
pp. 994-997 ◽  
Author(s):  
Jian Bo Lei ◽  
Zhen Wang ◽  
Yun Shan Wang
Keyword(s):  
Temperature Distribution ◽  
Temperature Gradient ◽  
Thermal Radiation ◽  
Metal Powder ◽  
Visible Region ◽  
Digital Signal ◽  
Processing Parameters ◽  
Measurement Results ◽  
Set Up ◽  
Powder Temperature

In order to study temperature distribution of metal powder stream in laser fabricating, its thermal radiation in visible region was detected by CCD. Based on Planck’s radiation law, the relation between molten powder temperature and its visible thermal radiation could be set up. The thermal radiation image signal of powder stream was transformed to digital signal which was used to analyzing its temperature distribution. It was shown that crosswise dimension of molten powder was about 2.5mm in diameter at the distance of 5mm from power nozzle. The powder out from powder nozzle was heated rapidly by laser. Temperature of powder in central axis regions was the highest which was nearly 2000K at the power of 1100w. The temperature gradient of powder at the edge of laser stream was greatly. The measurement results could be used to optimize the design of powder nozzle and processing parameters of laser fabricating.

scholarly journals A frame for a computer aided inspection planning system

2015 ◽  
Vol 4 (1) ◽  
pp. 125 ◽  
Author(s):  
Wilma Polini ◽  
Giovanni Moroni
Keyword(s):  
Measurement Techniques ◽  
Coordinate Measuring Machine ◽  
Planning System ◽  
Inspection Planning ◽  
Coordinate Measurement ◽  
Measurement Results ◽  
Measuring Machine ◽  
Set Up ◽  
Almost All ◽  
Computer Aided Inspection

Coordinate Measuring Machine (CMM) inspection planning is an activity performed by well-trained operators, but different measurement techniques, using the same data analysis algorithms yield in different measurement results. This is a well-recognized source of uncertainty in coordinate measurement. A CMM, provided with an automatic inspection planning (CAIP) system, permits to implement more accurate and efficient operating procedures and to fit higher quality assurance standards and tighter production timings.In this paper we present a frame of a CAIP system, able to deal with almost all the decisional stages of CMM inspection. Moreover, original approaches have been developed and presented in inspection feature selection, part set-up, probe configuration, and path planning.

Identification of thermal parameters of a building envelope based on the cooling process of a building object

2019 ◽  
Vol 43 (6) ◽  
pp. 503-527 ◽  
Author(s):  
Iwona Pokorska-Silva ◽  
Artur Nowoświat ◽  
Lidia Fedorowicz
Keyword(s):  
Thermal Conductivity ◽  
Regression Model ◽  
Multiple Regression ◽  
Analytical Model ◽  
Multiple Regression Model ◽  
Building Envelope ◽  
Thermal Parameters ◽  
Cooling Process ◽  
Building Envelopes ◽  
Measurement Results

Thermal properties of building envelopes are often described using thermal conductivity or thermal resistance. And the opposite task involves the identification of thermal parameters of building envelopes based on the measurements of their cooling process. In this article, the authors proposed a method of identifying thermal parameters of a building envelope based on cooling measurements, using a multiple regression model for this purpose. To satisfy the research objectives, two basic experiments were carried out. The first experiment was performed in laboratory conditions. The research model was a cube of the dimensions of 1.1 m × 1.1 m × 1.1 m. The second experiment was carried out in semi-real conditions, and the used model was a small house of the dimensions of 6.0 m × 4.15 m × 5.2 m. The measurement results were also used to calibrate numerical models made in the ESP-r program. The research studies have demonstrated that the model can be used to identify thermal parameters of a building envelope. Based on the measurements and simulations, the cooling equations of the object were determined and the 95% confidence interval for the heat retention index was estimated. On that basis, using the multiple regression model, such parameters of the model as density, specific heat, and thermal conductivity were estimated. It turned out that using the Gauss–Newton approximation, we obtained the correlation of the measurement results and the analytical model with the correlation coefficient of 0.9971 (for the laboratory scale). And the multiple regression improved not only the correlation between the measurement and the analytical model, but it also allowed to obtain “almost identical” results. Similarly, promising results were obtained for the semi-real scale.

scholarly journals Characterization of a Micro-Opto-Mechanical Transducer for the Electric Field Strength

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 855
Author(s):  
Wilfried Hortschitz ◽  
Andreas Kainz ◽  
Harald Steiner ◽  
Gabor Kovacs ◽  
Michael Stifter ◽  
...  
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Resolution Limit ◽  
Strength Based ◽  
Measurement Results ◽  
Mechanical Transducer ◽  
Mems Technology ◽  
Order Of Magnitude ◽  
Set Up

We report on a new optical sensing principle for measuring the electric field strength based on MEMS technology. This method allows for distortion-free and point-like measurements with high stability regarding temperature. The main focus of this paper rests on an enhanced measurement set-up and the thereby obtained measurement results. These results reveal an improved resolution limit and point to the limitations of the current characterization approach. A resolution limit of 222 V/m was achieved while a further improvement of roughly one order of magnitude is feasible.

Using Linear Superposition to Solve Multiple Heat Source Transient Thermal Problems

2007 ◽  
Author(s):  
David T. Billings ◽  
Roger P. Stout
Keyword(s):  
Heat Source ◽  
Transient Response ◽  
Response Curves ◽  
Linear Superposition ◽  
Circuit Simulator ◽  
Set Up ◽  
The Time Domain ◽  
The Individual ◽  
Transient Thermal ◽  
Application Engineer

For many years engineers have been using linear superposition to solve steady state thermal problems with multiple-heat-source systems. Predicting transient response of single-heat-source systems has been performed using R-C Foster networks with reasonable success. In most real applications there are multiple heat sources that are interacting perhaps in very complex ways in the time domain. Being able to simulate these interactions using a spreadsheet tool or a circuit simulator may be very advantageous to a device or application engineer designing or evaluating an application design. Using an RC-network model of a system to represent the individual transient response curves, we’ll show how to do this bookkeeping (and all the other calculations) for a simple system using Microsoft Excel. We’ll also see how to set up this sort of problem in a circuit simulator.

Experimental determination of thermal conductivity of composite materials in a wide range of values at room temperature

2019 ◽  
Author(s):  
A.N. Chistov ◽  
M.Yu. Kladov ◽  
I.B. Pronin ◽  
A.S. Smirnov
Keyword(s):  
Thermal Conductivity ◽  
Composite Materials ◽  
Room Temperature ◽  
Measurement Procedure ◽  
Thermal Mode ◽  
Wide Range ◽  
Measurement Results ◽  
Transfer Problems ◽  
Range Of Values

In developing new composite materials and solving heat transfer problems, the thermal conductivity is an important characteristic that must be reliably determined. This often requires samples of the smallest dimensions, which is relevant for the production of pilot batches of material, as well as if they are taken directly from the product, when the amount of material is very limited. Most common methods for determining thermal conductivity require samples of relatively large sizes. To measure thermal conductivity on small-sized samples, an upgraded benchtop instrument is introduced. The instrument uses the relative method of longitudinal heat flux, which consists in a comparative measurement of a sample located between the heater and the standard in a stationary thermal mode. This paper presents the instrument design details, the requirements for the samples, explains the calibration features and the measurement procedure. The measurement results in a number of composite materials, as well as in materials with well-studied properties are analyzed. Findings show that the error of determining the thermal conductivity on a modernized instrument does not exceed several percent.

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