Thermal Management of Voids and Delamination in TIMs

2005 ◽  
Author(s):  
Vadim Gektin
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Performance Analysis ◽  
Effective Thermal Conductivity ◽  
Thermal Management ◽  
Thermal Performance ◽  
Power Dissipation ◽  
Thermal Measurements ◽  
The Impact ◽  
The Relationship

The paper parametrically assesses the impact of the voids/delamination on the system thermal performance. Analysis are carried out numerically and validated against experimental data (thermal measurements and C-SAM images). Topics covered include the relationship between voids/delamination and TIMs’ and heat spreader’s effective thermal conductivity; sensitivity of the system thermal performance to void/delamination size and location; voids/delamination impact vs. on the chip power dissipation (uniform vs. non-uniform); comparison of TIM1 vs. TIM2 voids impact; and, finally, comparison of voids vs. delamination.

The Effective Thermal Conductivity of Porous Polymethacrylimide Foams

2014 ◽  
Vol 609-610 ◽  
pp. 196-200 ◽  
Author(s):  
Peng Yue ◽  
Lin Qiu ◽  
Xing Hua Zheng ◽  
Da Wei Tang
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Formation Mechanism ◽  
3Ω Method ◽  
Temperature Range ◽  
Different Temperatures ◽  
The Relationship

A freestanding sensor-based 3ω method was employed to measure the effective thermal conductivity of porous polymethacrylimide (PMI) foams with different densities at different temperatures. Experimental data showed that within the measuring temperature range, the effective thermal conductivity increased with temperature. Moreover, the formation mechanism of the relationship between the effective thermal conductivity and temperature was analyzed in this paper.

Experimental Investigation of Thermal Conduction Performance on Silicon-Based Micro Flat Heat Pipe

2015 ◽  
Vol 645-646 ◽  
pp. 1032-1037
Author(s):  
Cong Ming Li ◽  
Yi Luo ◽  
Chuan Peng Zhou ◽  
Liang Liang Zou ◽  
Xiao Dong Wang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Pipe ◽  
Effective Thermal Conductivity ◽  
Thermal Performance ◽  
Axial Direction ◽  
Filling Ratio ◽  
Parallel Structure ◽  
Working Fluid ◽  
Vacuum Degree ◽  
Structure Dimension

There are several factors that affect heat transfer of heat pipe, for example, structure dimension, filling ratio and vacuum degree of charging. This paper studied the thermal conductivity of micro flat heat pipes (MFHPs) with different structure dimension and with different filling ratio, when the charging vacuum degree of MFHP was decided. When electric power was 2W or 4W, MFHPs with parallel grooves and nonparallel grooves, charged by working fluid with different filling ratio, were carried out. And the filling ratio is 30%, 40% and 50%, respectively. The better thermal performance of MFHP can be evaluated by lower thermal resistance and higher effective thermal conductivity. The experiment results show that MFHP has the highest effective thermal conductivity when the filling ratio is 40%; and the thermal performance of MFHP with nonparallel structure in axial direction is better than that of MFHP with parallel structure.

Thermo-Optic Tuning Efficiency of Micro Ring Resonators on Low Thermal Resistance Silicon Photonics Substrates

2017 ◽  
Author(s):  
Shenghui Lei ◽  
Alexandre Shen ◽  
Ryan Enright
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Thermal Performance ◽  
Silicon Photonics ◽  
Communication Systems ◽  
Device Fabrication ◽  
Ring Resonators ◽  
Wide Range ◽  
Soi Substrates ◽  
The Impact

Silicon photonics has emerged as a scalable technology platform for future optotelectronic communication systems. However, the current use of SiO2-based silicon-on-insulator (SOI) substrates presents a thermal challenge to integrated active photonic components such as lasers and semiconductor optical amplifiers due to the poor thermal properties of the buried SiO2 optical cladding layer beneath these devices. To improve the thermal performance of these devices, it has been suggested that SiO2 be replaced with aluminum nitride (AlN); a dielectric with suitable optical properties to function as an effective optical cladding that, in its crystalline state, demonstrates a high thermal conductivity (∼100× larger than SiO2 in current SOI substrates). On the other hand, the tuning efficiencies of thermally-controlled optical resonators and phase adjusters, crucial components for widely tunable lasers and modulators, are directly proportional to the thermal resistance of these devices. Therefore, the low thermal conductivity buried SiO2 layer in the SOI substrate is beneficial. Moreover, to further improve the thermal performance of these devices air trenches have been used to further thermally isolate these devices, resulting in up to ∼10× increase in tuning efficiency. Here, we model the impact of changing the buried insulator on a SOI substrate from SiO2 to high quality AlN on the thermal performance of a MRR. We map out the thermal performance of the MRR over a wide range of under-etch levels using a thermo-electrical model that incorporates a pseudo-etching approach. The pseudo-etching model is based on the diffusion equation and distinguishes the regions where substrate material is removed during device fabrication. The simulations reveal the extent to which air trenches defined by a simple etch pattern around the MRR device can increase the thermal resistance of the device. We find a critical under-etch below which no benefit is found in terms of the MRR tuning efficiency. Above this critical under-etch, the tuning efficiency increases exponentially. For the SiO2-based MRR, the thermal resistance increases by ∼7.7× between the un-etched state up to the most extreme etch state. In the unetched state, the thermal resistance of the AlN-based MRR is only ∼4% of the SiO2-based MRR. At the extreme level of under-etch, the thermal resistance of the AlN-based MRR is still only ∼60% of the un-etched SiO2-based MRR. Our results suggest the need for a more complex MRR thermal isolation strategy to significantly improve tuning efficiencies if an AlN-based SOI substrate is used.

An Experimental Study on the Thermal Performance Evaluation of SCW Ground Heat Exchanger

2017 ◽  
Vol 25 (01) ◽  
pp. 1750006 ◽  
Author(s):  
Keun Sun Chang ◽  
Min Jun Kim ◽  
Young Jae Kim
Keyword(s):  
Thermal Conductivity ◽  
Performance Evaluation ◽  
Heat Exchanger ◽  
Effective Thermal Conductivity ◽  
Thermal Performance ◽  
Thermal Response ◽  
High Heat ◽  
Injection Rate ◽  
Operating Parameters ◽  
Ground Heat Exchanger

In recent years, application of the standing column well (SCW) ground heat exchanger (GHX) has been noticeably increased as a heat transfer mechanism of ground source heat pump (GSHP) systems with its high heat capacity and efficiency. Determination of the ground thermal properties is an important task for sizing and estimating cost of the GHX. In this study, an in situ thermal response test (TRT) is applied to the thermal performance evaluation of SCW. Two SCWs with different design configurations are installed in sequence to evaluate their effects on the thermal performance of SCW using a single borehole. A line source method is used to derive the effective thermal conductivity and borehole thermal resistance. Effects of operating parameters are also investigated including bleed, heat injection rate, flow rate and filler height. Results show that the effective thermal conductivity of top drawn SCW (Type A) is 11.7% higher than that of bottom drawn SCW (Type B) and of operating parameters tested bleed is the most significant one for the improvement of the thermal performance (40.4% enhanced in thermal conductivity with 10.9% bleed).

THE EFFECT OF VERTICAL AIR GAPS TO THERMAL TRANSMITTANCE OF HORIZONTAL THERMAL INSULATING LAYER

2009 ◽  
Vol 15 (3) ◽  
pp. 309-315 ◽  
Author(s):  
Jolanta Šadauskienė ◽  
Andrius Buska ◽  
Arūnas Burlingis ◽  
Raimondas Bliūdžius ◽  
Albinas Gailius
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Thermal Insulation ◽  
Standard Method ◽  
Mineral Wool ◽  
Insulating Layer ◽  
Air Gaps ◽  
Thermal Transmittance ◽  
Thermal Insulating ◽  
The Impact

In order to reduce the amounts of work at the construction site, single‐ply dual density thermal insulating roofing boards are used with increasing frequency for thermal insulation of flat roofs. In this case, the joints between boards are not overlapped by the other ply over it; therefore gaps of varying width form between the sides of the boards through the entire thickness of the insulating layer, whose effect on the effective thermal conductivity of the thermal insulating layer must be evaluated. The aim of this project was to assess the reliability of standard method, used to determine the impact of such air gaps on the effective thermal conductivity of the thermal insulating layer by comparing the results of calculations and the results of measurements of thermal conductivity, also to determine the correction factors for thermal transmittance of horizontal thermal insulation layers due to the forming vertical air gaps between the single‐ply mineral wool boards. After measurements of thermal resistances of 50 mm thick thermal insulation board with the air gaps which width varied from 3 mm to 20 mm, it was determined that the thermal conductivity value of the air gaps increases with the increment of the width of air gaps. After completion the experimental measurements of thermal conductivity it was determined that the height of closed and unventilated or partly ventilated air gaps has no effect on the properties of effective thermal conductivity of the thermal insulation layer when the air gap width is up to 5 mm. When wider unventilated or partly ventilated air gaps occur, the effective thermal conductivity coefficient increases proportionally as the height of the air gaps increases. Calculated according to the standard method the affix to the thermal transmittance is overly general and not always appropriate. In some cases it is 6 times higher or 4 times lower than the measured one. In this paper a method to evaluate the effects of air gaps by the use of correction factor to the thermal transmittance of the horizontal thermal insulating layer is proposed. Santrauka Nornt sumažinti darbų apimtis statybos vietoje, stogams šiltinti vis dažniau naudojamos vienu sluoksniu klojamos dvitankės termoizoliacinės plokštės. Šiuo atveju plokščių sandūros neperdengiamos, todėl tarp plokščių kraštinių susidaro įvairaus pločio plyšių, kurių įtaka termoizoliacinio sluoksnio šilumai perduoti turi būti įvertinta. Šio darbo tikslas yra įvertinti standartinio metodo, taikomo tokių plyšių poveikiui sluoksnio šilumos laidumui, patikimumui nustatyti lyginant skaičiavimo ir šilumos laidumo matavimų rezultatus, nustatyti horizontaliojo termoizoliacinio sluoksnio šilumos perdavimo koeficiento pataisas dėl vertikaliųjų oro plyšių susidarymo. Apskaičiavus 50 mm storio termoizoliacinio sluoksnio oro plyšių šilumines varžas, kai plyšių plotis yra nuo 3–20 mm, nustatyta, kad oro plyšių šilumos laidumo koeficiento vertė didėja didėjant oro plyšio pločiui. Atlikus eksperimentinius šilumos laidumo matavimus, nustatyta, kad susidarančių uždarų ir nevėdinamų arba iš dalies vėdinamų oro plyšių aukštis neturi įtakos termoizoliacinio sluoksnio šilumos laidumo savybėms, kai oro plyšys yra iki 5 mm pločio. Esant platesniems uždariems ir nevėdinamiems oro plyšiams, šilumos laidumo koeficientas proporcingai didėja didėjant oro plyšių aukščiui. Pagal standartinį metodą skaičiuotas šilumos perdavimo koeficiento priedas yra per daug apibendrinantis ir ne visada tinkamas. Kai kuriais atvejais jis yra 6 kartus didesnis arba 4 kartus mažesnis už išmatuotąjį. Šiame darbe pasiūlytas horizontaliojo termoizoliacinio sluoksnio šilumos perdavimo koeficiento priedo, naudojamo plyšių įtakai įvertinti, skaičiavimo metodas.

A Simplified Model for Effective Thermal Conductivity of Highly Porous Ceramic Fiber Insulation

2015 ◽  
Vol 7 (4) ◽  
Author(s):  
Nicholas P. G. Lumley ◽  
Emory Ford ◽  
Eric Minford ◽  
Jason M. Porter
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Natural Convection ◽  
Effective Thermal Conductivity ◽  
Research Effort ◽  
Porous Ceramic ◽  
Ceramic Fiber ◽  
Chemical Process Industry ◽  
Thermophysical Model ◽  
Highly Porous

Highly porous ceramic fiber insulations are beginning to be considered as a replacement for firebrick insulations in high temperature, high pressure applications by the chemical process industry. However, the implementation of such materials has been impeded by a lack of experimental data and predictive models, especially at high gas pressure. The goal of this work was to develop a general, applied thermophysical model to predict effective thermal conductivity, keff, of porous ceramic fiber insulation materials and to determine the temperature, pressure, and gas conditions under which natural convection is a possible mode of heat transfer. A model was developed which calculates keff as the sum of conduction, convection, and radiation partial conductivities. The model was validated using available experimental data, including laboratory measurements made by this research effort. Overall, it was concluded that natural convection is indeed possible for the most porous insulations at pressures exceeding 10 atm. Furthermore, keff for some example insulations was determined as a function of temperature, pressure, and gas environment.

THE EXPERIMENTAL INVESTIGATION OF THE PROFIT DISTRIBUTION IN INDUSTRIAL SUPPLY CHAINS WITH AN OUTSIDE OPTION / PELNO PASKIRSTYMO PRAMONINĖSE TIEKIMO GRANDINĖSE EKSPERIMENTINIS TYRIMAS

2010 ◽  
Vol 16 (3) ◽  
pp. 487-501 ◽  
Author(s):  
Harald David Stein ◽  
Romualdas Ginevičius
Keyword(s):  
Experimental Data ◽  
Outside Option ◽  
Profit Distribution ◽  
Cooperative Relationships ◽  
Distribution Rule ◽  
Internet Experiments ◽  
Theoretical Predictions ◽  
Cooperation Partners ◽  
The Impact ◽  
The Relationship

There is an industrial supply chain, where an individual customer selects a supplier and excludes other ones. If the excluded supplier has the possibility to overtake the relationship afterwards, he has big influence on the relationship among the cooperation partners. A profit distribution rule has been developed that considers the impact of the excluded supplier. The paper presents round based games in which the present values change and influence the cooperative relationships. First, examples with ideal‐typical numbers are calculated and depicted by the software “MATLAB”. Internet experiments are made with participants on the basis of the software “z‐tree” in order prove the relevance of the proposed profit distribution rule. Finally, the experimental data is compared with the theoretical predictions. Santrauka Paprastai pramoninio tiekimo grandineje klientas pasirenka konkretų tiekėja ir atmeta kitus. Jei veliau su atmestuoju tiekėju vis dėlto užmezgami santykiai, klientas įgyja didelę svarbą pletojant partnerių santykius. Sukurta pelno paskirstymo taisyklė, įvertinanti atmesto tiekejo įtaka. Straipsnyje pateikiama serija žaidimų, kuriuose kinta esama vertė ir daroma įtaka partnerių santykiams. Pirma, naudojantis MATLAB programinė įranga apskaičiuojamos ir atvaizduojamos būdingosios reikšmės. Antra, pasitelkus Z‐tree programinę įranga atliktas internetinis eksperimentas siekiant įrodyti, kad pasiūlyta pelno paskirstymo taisyklė galioja. Galiausiai eksperimentiniai duomenys palyginami su teorinėmis prognozėmis.

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