scholarly journals The Results of the Testing of Led Light According to the Method of Measuring the Lighting Engineering Parameters

2018 ◽  
pp. 3-8
Author(s):  
A. Kolesnyk ◽  
D. Usichenko ◽  
L. Nazarenko
Keyword(s):  
Cost Effectiveness ◽  
Heat Removal ◽  
High Heat ◽  
High Heat Flux ◽  
Thermal Mode ◽  
Led Lighting ◽  
Led Light ◽  
Software Complex ◽  
The Individual ◽  
The Cost

LED lighting sources, appeared on the market in the 60s of the last century, are the most effective option and it is the fastest developing lighting technology for now. The problem of efficient heat removal from the LED becomes to be one of the basic ones. Due to high heat flux on the individual diodes surface, problems related to the light source cooling become to be one of the most. Modeling and thermal calculations are the solution to the problem of heat sink and maintenance of optimal thermal mode of operation of LEDs. One of the biggest drawbacks of LED lighting is the excessive price, so it is important to take into account the cost-effectiveness in selecting the components of the luminaire, and use the resour­ces correctly. In the conducted research the model of the LED light in the software complex has been designed and analyzed. And a real sample was made. As a rule, the corresponding photometric characteristics are determined depending on the field of application of the light device. In addition, the conditions of this coil are taken into account in the overload mode. Photometric characteristics and thermographic calculations for 75 W and 90 W have been measured. This proves the cost-effectiveness of a projected luminaire, using a power supply of Mean Well. The paper presents the results of light enginee­ring calculations and thermographic analysis of a sample LED device. Experimental and computational data have been compared and discussed.

STABLE, CALM, AND HIGH-HEAT-FLUX HEAT REMOVAL USING A POROUS-MICRO-CHANNEL

2017 ◽  
Author(s):  
Tomio Okawa ◽  
Junki Ohashi ◽  
Ryo Hirata ◽  
Koji Enoki
Keyword(s):  
Heat Flux ◽  
Heat Removal ◽  
High Heat ◽  
High Heat Flux ◽  
Micro Channel

scholarly journals Cost-Effectiveness of an Exercise Programme that Provided Group or Individual Training to Reduce the Fall Risk in Healthy Community-Dwelling People Aged 65–80: A Secondary Data Analysis

Healthcare ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 714
Author(s):  
Isaac Aranda-Reneo ◽  
Laura Albornos-Muñoz ◽  
Manuel Rich-Ruiz ◽  
María Ángeles Cidoncha-Moreno ◽  
Ángeles Pastor-López ◽  
...  
Keyword(s):  
Economic Evaluation ◽  
Cost Effectiveness ◽  
Older People ◽  
Incremental Cost ◽  
Fall Risk ◽  
Community Dwelling ◽  
Effective Measure ◽  
The Individual ◽  
The Cost ◽  
Individual Training

Research has demonstrated that some exercise programs are effective for reducing fall rates in community-dwelling older people; however, the literature is limited in providing clear recommendations of individual or group training as a result of economic evaluation. The objective of this study was to assess the cost-effectiveness of the Otago Exercise Program (OEP) for reducing the fall risk in healthy, non-institutionalized older people. An economic evaluation of a multicenter, blinded, randomized, non-inferiority clinical trial was performed on 498 patients aged over 65 in primary care. Participants were randomly allocated to the treatment or control arms, and group or individual training. The program was delivered in primary healthcare settings and comprised five initial sessions, ongoing encouragement and support to exercise at home, and a reinforcement session after six months. Our hypothesis was that the patients who received the intervention would achieve better health outcomes and therefore need lower healthcare resources during the follow-up, thus, lower healthcare costs. The primary outcome was the incremental cost-effectiveness ratio, which used the timed up and go test results as an effective measure for preventing falls. The secondary outcomes included differently validated tools that assessed the fall risk. The cost per patient was USD 51.28 lower for the group than the individual sessions in the control group, and the fall risk was 10% lower when exercises had a group delivery. The OEP program delivered in a group manner was superior to the individual method. We observed slight differences in the incremental cost estimations when using different tools to assess the risk of fall, but all of them indicated the dominance of the intervention group. The OEP group sessions were more cost-effective than the individual sessions, and the fall risk was 10% lower.

Thermo-Fluid-Stress-Deformation Analysis of Two-Layer Microchannels for Cooling Chips With Hot Spots

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Abas Abdoli ◽  
George S. Dulikravich ◽  
Genesis Vasquez ◽  
Siavash Rastkar
Keyword(s):  
Heat Flux ◽  
Thermal Stresses ◽  
Hot Spot ◽  
Heat Removal ◽  
High Heat ◽  
Heat Transfer Analysis ◽  
Deformation Analysis ◽  
High Heat Flux ◽  
Cooling Design ◽  
Microchannel Cooling

Two-layer single phase flow microchannels were studied for cooling of electronic chips with a hot spot. A chip with 2.45 × 2.45 mm footprint and a hot spot of 0.5 × 0.5 mm in its center was studied in this research. Two different cases were simulated in which heat fluxes of 1500 W cm−2 and 2000 W cm−2 were applied at the hot spot. Heat flux of 1000 W cm−2 was applied on the rest of the chip. Each microchannel layer had 20 channels with an aspect ratio of 4:1. Direction of the second microchannel layer was rotated 90 deg with respect to the first layer. Fully three-dimensional (3D) conjugate heat transfer analysis was performed to study the heat removal capacity of the proposed two-layer microchannel cooling design for high heat flux chips. In the next step, a linear stress analysis was performed to investigate the effects of thermal stresses applied to the microchannel cooling design due to variations of temperature field. Results showed that two-layer microchannel configuration was capable of removing heat from high heat flux chips with a hot spot.

scholarly journals Calculation of the thermal mode of the LED device

2019 ◽  
pp. 146-148
Author(s):  
Natalia Kulik ◽  
Jakov Danchenkov
Keyword(s):  
Calculation Method ◽  
Heat Removal ◽  
Light Sources ◽  
Thermal Mode ◽  
Led Light ◽  
Modern Methods ◽  
The Given

The problem of heat removal from the substrate of LED light sources is considered. Modern methods of cooling of LEDs are reviewed. The calculation method is given and the radiator area for passive heat removal is calculated. The radiator was selected according to the given criteria.

First Fundamental Decision of the Federal Supreme Court of Switzerland on Cost-Effectiveness in the Area of Human Healthcare

2011 ◽  
Vol 2 (3) ◽  
pp. 442-446 ◽  
Author(s):  
Felix Kesselring
Keyword(s):  
Cost Effectiveness ◽  
Supreme Court ◽  
Maximum Amount ◽  
Public Health Insurance ◽  
Health Insurance Provider ◽  
The Individual ◽  
The Cost ◽  
First Time ◽  
Federal Supreme ◽  
Human Healthcare

In rendering this decision, the Federal Supreme Court of Switzerland entered for the first time into a detailed analysis of questions relating to the cost-effectiveness of human healthcare. The decision, concerned with the availability of a drug for a rare genetic disease, makes it clear that the maximum amount available from a public health insurance provider for the medical treatment in a particular case has been reached once the amount requested by the individual patient cannot also be provided to all other persons in a comparable situation. It remains unclear, however, how cost-effectiveness is to be assessed below this maximum amount (author's headnote).

scholarly journals Influence of the ambient temperature on the cooling efficiency of the high performance cooling device with thermosiphon effect

2018 ◽  
Vol 180 ◽  
pp. 02073
Author(s):  
Patrik Nemec ◽  
Milan Malcho
Keyword(s):  
Ambient Temperature ◽  
High Performance ◽  
Convection Heat Transfer ◽  
Heat Removal ◽  
Measuring Method ◽  
High Heat ◽  
Heat Fluxes ◽  
High Heat Flux ◽  
Cooling Efficiency ◽  
Cooling Device

This work deal with experimental measurement and calculation cooling efficiency of the cooling device working with a heat pipe technology. The referred device in the article is cooling device capable transfer high heat fluxes from electric elements to the surrounding. The work contain description, working principle and construction of cooling device. The main factor affected the dissipation of high heat flux from electronic elements through the cooling device to the surrounding is condenser construction, its capacity and option of heat removal. Experimental part describe the measuring method cooling efficiency of the cooling device depending on ambient temperature in range -20 to 40°C and at heat load of electronic components 750 W. Measured results are compared with results calculation based on physical phenomena of boiling, condensation and natural convection heat transfer.

Dependence of Heat Transfer Coefficient on Porous Structure in Porous Media

2008 ◽  
Author(s):  
Akira Matsui ◽  
Kazuhisa Yuki ◽  
Hidetoshi Hashizume
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Porous Media ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
High Performance ◽  
Heat Removal ◽  
High Heat ◽  
Metal Foams ◽  
High Heat Flux

Detailed heat transfer characteristics of particle-sintered porous media and metal foams are evaluated to specify the important structural parameters suitable for high heat removal. The porous media used in this experiment are particle-sintered porous media made of bronze and SUS316L, and metal foams made of copper and nickel. Cooling water flows into the porous medium opposite to heat flux input loaded by a plasma arcjet. The result indicates that the bronze-particle porous medium of 100μm in pore size shows the highest performance and achieves heat transfer coefficient of 0.035MW/m2K at inlet heat flux 4.6MW/m2. Compared with the heat transfer performance of copper fiber-sintered porous media, the bronze particlesintered ones give lower heat transfer coefficient. However, the stable cooling conditions that the heat transfer coefficient does not depend on the flow velocity, were confirmed even at heat flux of 4.6MW/m2 in case of the bronze particle-sintered media, while not in the case of the copper-fiber sintered media. This signifies the possibility that the bronze-particle sintered media enable much higher heat flux removal of over 10MW/m2, which could be caused by higher permeability of the particle-sintered pore structures. Porous media with high permeability provide high performance of vapor evacuation, which leads to more stable heat removal even under extremely high heat flux. On the other hand, the heat transfer coefficient of the metal foams becomes lower because of the lower capillary and fin effects caused by too high porosity and low effective thermal conductivity. It is concluded that the pore structure having high performance of vapor evacuation as well as the high capillary and high fin effects is appropriate for extremely high heat flux removal of over 10MW/m2.

Copper-Carbon Nanotube Micropillars for Passive Thermal Management of High Heat Flux Electronic Devices

2020 ◽  
Author(s):  
Gerardo Rojo ◽  
Jeff Darabi
Keyword(s):  
Thermal Management ◽  
Thermal Performance ◽  
Computational Study ◽  
Copper Substrate ◽  
Heat Removal ◽  
Cost Effective ◽  
High Heat ◽  
Operating Conditions ◽  
High Heat Flux ◽  
Micropillar Array

Abstract Miniaturization of electronic products and a consequent rapid increase in power density of advanced microprocessors and electronic components have created a need for improved cooling techniques to efficiently remove heat from such devices. Traditional air-cooled heat sinks have been utilized for several decades as the most cost-effective cooling technique for electronic cooling applications. However, the existing thermal management solutions are unable to maintain the temperature of the next generation of complex electronic systems within acceptable limits without adding considerable weight and complexity. This paper reports a microstructured wick for application in passive thermal management systems such as heat pipes and vapor chambers. The wick structure consists of mushroom-like composite copper-carbon nanotubes (Cu-CNT) micropillars. The small spacing between micropillar heads provides a higher capillary pressure whereas the large spacing between the base of micropillars provides a higher permeability for liquid flow. The micropillar array was fabricated on a copper substrate using an electroplating technique. The micropillar array was then tested in a controlled environment to experimentally measure its thermal performance under several operating conditions. A heat removal capability of 80 W/cm2 was demonstrated at a wall superheat of 15° C. In addition, a computational study was performed using ANSYS Fluent to predict the thermal performance of the micropillar array. Model predictions were compared with the experimental results and good agreement was obtained.

10310 A study on high heat flux heat removal with phase change using a porous metal

2014 ◽  
Vol 2014.20 (0) ◽  
pp. _10310-1_-_10310-2_
Author(s):  
Daiki Hanzawa ◽  
Kyosuke Katsumata ◽  
Tomio Okawa
Keyword(s):  
Heat Flux ◽  
Phase Change ◽  
Heat Removal ◽  
Porous Metal ◽  
High Heat ◽  
High Heat Flux

A Study on High Heat Flux Heat Removal With Boiling Using Porous Microchannel

2014 ◽  
Author(s):  
Daiki Hanzawa ◽  
Kyosuke Katsumata ◽  
Tomio Okawa
Keyword(s):  
Heat Flux ◽  
Pore Size ◽  
Mass Flux ◽  
Pressure Loss ◽  
Heat Removal ◽  
Porous Metal ◽  
High Heat ◽  
High Mass ◽  
High Heat Flux ◽  
Small Flow

This paper reports the critical heat flux (CHF) enhancement that was observed experimentally when a porous metal was placed in a small flow channel (hereafter, this channel is called a “porous microchannel”). In the porous microchannel, the CHF value increased almost linearly with increased values of the mass flux and the inlet subcooling. In consequence, higher cooling performance was achieved under high mass flux and high inlet subcooling conditions. It was also found that considerable fluctuation of the pressure loss frequently encountered in a small heated channel disappears in the porous microchannel. It was considered that the stabilization of the pressure loss can mainly be attributed to inhibition of the formation of large bubbles. The effects of the material and the pore size of the porous metal were also investigated. Silver and nickel were selected as the porous metal material and the pore size tested was 0.2 and 0.6 mm. In the present experiments, the CHF value was not influenced significantly by the material in spite of the distinct difference of the thermal conductivity between silver and nickel, whilst it was dependent noticeably on the pore size. It was hence suggested that the CHF enhancement observed in this work was mainly caused by the complex thermal-hydraulic field formed in the porous microchannel. Preliminary results of the flow visualization performed to reveal the mechanisms of the CHF enhancement in the porous microchannel was also reported.

Sign in / Sign up

Export Citation Format

Share Document