Research Into The Junction Temperature And Power Of New Led Modules Generation In Dependence On Variable Parameters

2020 ◽  
pp. 106-115
Author(s):  
Kemal Furkan Sokmen ◽  
Osman Bedrettin Karatas
Keyword(s):  
Adverse Effect ◽  
Ambient Temperature ◽  
Finite Volume ◽  
Luminous Flux ◽  
Junction Temperature ◽  
Variable Parameters ◽  
Factors Affecting ◽  
Volume Analysis ◽  
Ambient Temperatures ◽  
New Generation

In this research, the change in the junction temperature and luminous flux of a new generation LED module depending on variables such as radiation, lens piece, ambient temperatures, currents, and quantity of elements had been studied. Commercial software FloEFD2019 was used in the finite volume analysis made during the study. The analyses were verified by experiments. On basis of the analysis, a solution was obtained that does not depend on the number of elements. The force of gravity was taken into account. While the ambient temperatures were taken as Ta = 23 °C and 40 °C, and the radiation value as 1009 W/m2, currents as 140 mA, 160 mA, 180 mA, 200 mA, 220 mA and 240 mA, meanwhile, samples numbers on PCB were taken as 101 and 202. In order to determine the effect of the lens piece located on the LED module, the analysis was repeated with and without using the lens. As a result of the study, it was found that the increase in ambient temperature and radiation has an adverse effect on the temperature Tj and luminous flux. It has been observed that changing samples number has a negligible effect on luminous flux and temperature Tj. It was found that the use of radiation and lenses are the most important factors affecting the luminous flux of the module.

The Study of Comparative Characterization between SiC MOSFET and Si- IGBT for Power Module and Three-Phase SPWM Inverter

2020 ◽  
Vol 1004 ◽  
pp. 1045-1053
Author(s):  
Heng Lee ◽  
Chun Kai Liu ◽  
Tao Chih Chang
Keyword(s):  
Ambient Temperature ◽  
Junction Temperature ◽  
System Level ◽  
Switching Frequency ◽  
Power Module ◽  
Ambient Temperatures ◽  
Three Phase ◽  
Type Power ◽  
Three Phase Inverter ◽  
Better Than

This paper focuses on how to define and integrate the system level and power module level with optimal conditions in SiC and Si-IGBT. To investigate the above situation, we compare the performance of SiC and Si-IGBT in power module and system level at different ambient temperatures. At the same maximum junction temperature 150°C and ambient temperature at 25°C and 80°C, it found that SiC type electrical resistance, maximum endurable current, and voltage could be better than the IGBT type power module above 20%. On the other hand, the simulation of three-phase inverter at different switching frequency such as 10kHz, 15kHz, 20kHz, 30kHz and it had been observed that the power loss of SiC inverter are 78% less for 10kHz switching frequency; 82% less for switching frequency at 15kHz; 85% less for 20kHz of switching frequency; 89% less for switching frequency at 30kHz in the Si-IGBT three-phase SPWM inverter at ambient temperature 80°C.

Efficiency Increase at Low Temperatures through Heat Accumulation Tube Sections in Synthetic Material Damp-Proof Luminaires with T5 Fluorescent Lamps

1970 ◽  
Vol 110 (4) ◽  
pp. 135-138
Author(s):  
F. Pracht
Keyword(s):  
Low Temperatures ◽  
Operational Efficiency ◽  
Luminous Flux ◽  
Synthetic Material ◽  
Heat Accumulation ◽  
Ambient Temperatures ◽  
Fluorescent Lamps ◽  
New Energy ◽  
Efficiency Increase ◽  
New Generation

The new energy-saving fluorescent lamp generation T5/16 mm exhibits an extremely high operational efficiency at room tempera-ture. However, low ambient temperatures cause a significantly reduced luminous flux and thus a low operational efficiency. It is there-fore for economic reasons not practical to deploy this new generation of lamps at low temperatures. In the present paper and engineering solution is discussed which is capable of improving the luminous flux in consideration of the special conditions in higher protection class luminaries. Ill. 2, bibl. 8 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.110.4.307

scholarly journals Assessment of methods of marking LED sources with the power of equivalent light bulb

2017 ◽  
Vol 65 (6) ◽  
pp. 883-890 ◽  
Author(s):  
P. Tabaka ◽  
P. Rozga
Keyword(s):  
Ambient Temperature ◽  
Luminous Flux ◽  
Point Of View ◽  
Potential User ◽  
Actual State ◽  
Light Bulb ◽  
Ambient Temperatures ◽  
State Of Affairs ◽  
The Given

Abstract This article presents considerations on the assessment of marking LED sources with the power of an equivalent light bulb. This problem was studied both on the basis of calculations and measurements performed. 17 LEDs of different powers and luminous fluxes were tested. Calculations assessing conformity with the declared power showed that an important disadvantage for most of the LED sources results from the method of marking them with the power of an equivalent light bulb from the point of view of the luminous flux emitted. Manufacturers do not do this correctly, misleading the potential user. Meanwhile, measurements performed in different ambient temperatures indicated that for only 4 from among the 13 LED sources studied the given value of the power of an equivalent light bulb may be recognized as in accordance with the actual state of affairs and still with a reservation that specified ambient temperature shall be required. In other cases the values of power quoted are either understated or overstated.

Comparison on the Thermo-Optical Performance of LEDs with MCPCB and FR4PCB under Various Drive Currents and Ambient Temperatures

2012 ◽  
Vol 488-489 ◽  
pp. 1369-1374
Author(s):  
N. Teeba ◽  
D. Mutharasu
Keyword(s):  
Optical Properties ◽  
Ambient Temperature ◽  
Junction Temperature ◽  
Optical Performance ◽  
Heat Management ◽  
Thermal Behaviors ◽  
Drive Current ◽  
Testing Conditions ◽  
Ambient Temperatures ◽  
Chromaticity Coordinates

Proper heat management is necessary for better performance of the LEDs. In the present study, the thermo-optical properties of the LED with different type of PCBs were analyzed. The measurement was done with two different testing conditions to identify the effect of increasing drive current at constant ambient temperature and increasing ambient temperature at constant drive current on the the LEDs with different PCBs. In both the conditions, the thermal behaviors of the LED are affected much due to different type of boards. As the drive current increases, the junction temperature and RthJA of the LED with MCPCB reduces around 3.7K/W and 15.3K/W compare with the LED with FR4. The change in magnitude of chromaticity coordinates of LED with FR4PCB and MCPCB calculated as 0.154 and 0.132 respectively. At a lower ambient temperature, the LEDs with FR4 and MCPCB record the RthJA as 71.2K/W and 50.6K/W respectively. However, these values were lowered around 15% at higher ambient temperatures for both the LEDs. As ambient temperature increases, the shift in chromaticity coordinates for the LEDs with MCPCB and FR4 was obtained as 0.0163 and 0.0165. The influence of the different type of PCB’s performance on LEDs was observed in the increasing drive current condition rather than the increasing ambient temperatures.

scholarly journals Influence of Ambient Temperature on Radiative and Convective Heat Dissipation Ratio in Polymer Heat Sinks

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2286
Author(s):  
Jan Kominek ◽  
Martin Zachar ◽  
Michal Guzej ◽  
Erik Bartuli ◽  
Petr Kotrbacek
Keyword(s):  
Heat Transfer ◽  
Ambient Temperature ◽  
Convective Heat ◽  
Heat Dissipation ◽  
High Surface ◽  
Heat Sinks ◽  
Fourth Power ◽  
Molding Process ◽  
Ambient Temperatures ◽  
University Of Technology

Miniaturization of electronic devices leads to new heat dissipation challenges and traditional cooling methods need to be replaced by new better ones. Polymer heat sinks may, thanks to their unique properties, replace standardly used heat sink materials in certain applications, especially in applications with high ambient temperature. Polymers natively dispose of high surface emissivity in comparison with glossy metals. This high emissivity allows a larger amount of heat to be dissipated to the ambient with the fourth power of its absolute surface temperature. This paper shows the change in radiative and convective heat transfer from polymer heat sinks used in different ambient temperatures. Furthermore, the observed polymer heat sinks have differently oriented graphite filler caused by their molding process differences, therefore their thermal conductivity anisotropies and overall cooling efficiencies also differ. Furthermore, it is also shown that a high radiative heat transfer leads to minimizing these cooling efficiency differences between these polymer heat sinks of the same geometry. The measurements were conducted at HEATLAB, Brno University of Technology.

scholarly journals Insufficient Stability of Clavulanic Acid in Widely Used Child-Appropriate Formulations

Antibiotics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 225
Author(s):  
Ines Mack ◽  
Mike Sharland ◽  
Janneke M. Brussee ◽  
Sophia Rehm ◽  
Katharina Rentsch ◽  
...  
Keyword(s):  
Ambient Temperature ◽  
Clavulanic Acid ◽  
Storage Conditions ◽  
Essential Medicines ◽  
Active Components ◽  
Middle Income ◽  
Ambient Temperatures ◽  
Essential Medicines List ◽  
Dispersible Tablets ◽  
The Stability

Amoxicillin-clavulanic acid (AMC) belongs to the WHO Essential Medicines List for children, but for optimal antimicrobial effectiveness, reconstituted dry powder suspensions need to be stored in a refrigerated environment. Many patients in low- and middle-income countries who are sold AMC suspensions would be expected not to keep to the specified storage conditions. We aimed to assess the stability of both ingredients in liquid formulations and dispersible tablets, combined with nationally representative data on access to appropriate storage. Degradation of amoxicillin (AMX) and clavulanic-acid (CLA) was measured in suspensions and dispersible tablets commercially available in Switzerland at different ambient temperatures (8 °C vs. 28 °C over 7 days, and 23 °C vs. 28 °C over 24 h, respectively). Data on access to refrigeration and electricity were assessed from the USAID-funded Demographic and Health Survey program. In suspensions, CLA degraded to a maximum of 12.9% (95% CI −55.7%, +29.9%) at 8°C and 72.3% (95% CI −82.8%, −61.8%) at a 28 °C ambient temperature during an observation period of 7 days. Dispersible tablets were observed during 24 h and CLA degraded to 15.4% (95% CI −51.9%, +21.2%) at 23 °C and 21.7% (−28.2%, −15.1%) at a 28 °C ambient temperature. There is relevant degradation of CLA in suspensions during a 7-day course. To overcome the stability challenges for all active components, durable child-appropriate formulations are needed. Until then, prescribers of AMC suspensions or pharmacists who sell the drug need to create awareness for the importance of proper storage conditions regarding effectiveness of both antibiotics and this recommendation should be reflected in the WHO Essential Medicines List for children.

Ambient temperature effects on physiological traits of white-tailed deer

1975 ◽  
Vol 53 (6) ◽  
pp. 679-685 ◽  
Author(s):  
J. B. Holter ◽  
W. E. Urban Jr. ◽  
H. H. Hayes ◽  
H. Silver ◽  
H. R. Skutt
Keyword(s):  
Heart Rate ◽  
Body Temperature ◽  
Energy Expenditure ◽  
Ambient Temperature ◽  
Temperature Effects ◽  
Temperature Changes ◽  
Wind Chill ◽  
Ambient Temperatures ◽  
Energy Equilibrium ◽  
Body Energy

Six adult white-tailed deer (Odocoileus virginianus borealis) were exposed to 165 periods of 12 consecutive hours of controlled constant ambient temperature in an indirect respiration calorimeter. Temperatures among periods varied from 38 to 0 (summer) or to −20C (fall, winter, spring). Traits measured were energy expenditure (metabolic rate), proportion of time spent standing, heart rate, and body temperature, the latter two using telemetry. The deer used body posture extensively as a means of maintaining body energy equilibrium. Energy expenditure was increased at low ambient temperature to combat cold and to maintain relatively constant body temperature. Changes in heart rate paralleled changes in energy expenditure. In a limited number of comparisons, slight wind chill was combatted through behavioral means with no effect on energy expenditure. The reaction of deer to varying ambient temperatures was not the same in all seasons of the year.

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