scholarly journals Analisis perancangan cooler box berbasis termoelektrik terhadap varian penggunaan thermal paste, faktor lingkungan dan heatsink

2021 ◽  
Vol 7 (1) ◽  
pp. 188
Author(s):  
Imron Rosyadi ◽  
Haryadi Haryadi ◽  
Novreza Pratama ◽  
M Haikal Fasya ◽  
Ade Irman ◽  
...  
Keyword(s):  
2021 ◽  
Author(s):  
Bharath Bharadwaj ◽  
Prashant Singh ◽  
Roop L. Mahajan

Abstract With increased focus on miniature high power density electronic packages, there is a need for the development of new interface materials with lower thermal resistance. To this end, high conductivity thermal paste or similar thermal interface materials (TIMs), reinforced with superior thermal conductivity materials such as multi-walled carbon nanotubes (MWCNTs), graphene nanoplatelets (GNPs), graphite-derived multilayer graphene (g-MLG) offer an effective strategy to provide efficient paths for heat dissipation from heat source to heat sink. In an earlier paper, we had demonstrated that multilayer graphene derived from coal (coal-MLG) synthesized using our in-house developed one-pot process, has increased presence of phenolic groups on its surfaces, which translates into better dispersion of coal-MLG in silicone thermal paste. In this paper, we first compare the thermal conductance of a high conductivity thermal paste (k = 8.9 W/mK) using coal-MLG as an additive with that realized with other nano additives — MWCNTs, GNPs, and g-MLG. The data shows that coal-MLG as an additive outperforms all the other investigated nano additives in enhancing the thermal performance of the paste. With the coal-MLG as an additive, ∼70% increase in thermal performance was observed as compared to the base thermal paste used. This increase is about 2.5 times higher than that obtained using g-MLG as an additive. We also measured the thermal performance of coal-MLG-based TIM with its different wt.% fractions. The data confirmed our hypothesis that the optimum level of the loading fraction of the additive that can be dispersed in the matrix (paste in this case) before the onset of agglomeration is higher for the coal-MLG (3%) than for the other additives (2%). The implication is further improvement thermal performance with coal-MLG. The data shows the additional thermal enhancement to ∼2X. Finally, since coal-MLG produced by our in-house process is relatively cheaper and more environmentally friendly, we believe that these results would pave the path for enhanced thermal performance with non-silicone thermal pastes at a significantly lower cost. We also expect similar benefits for the silicone-based thermal pastes.


1991 ◽  
Vol 6 (5) ◽  
pp. 1082-1093 ◽  
Author(s):  
I. Sushumna ◽  
R.K. Gupta ◽  
E. Ruckenstein

Highly concentrated solid-in-liquid suspensions find applications in a number of areas such as electronics, ceramics, paints, coatings, etc. Highly loaded, stable suspensions which exhibit desirable rheological characteristics (moderate viscosity, shear thinning behavior, thixotropy, and a small yield stress, for example), and which have high thermal or electrical conductivities are frequently sought after. We describe here some techniques which can be used to obtain such highly concentrated suspensions. These involve employing mixed size grades of particles and effective dispersants. For thermal paste applications, for example, compliant pastes of up to 78 vol. % solids with thermal conductivity values as high as 6 W/mK (hence, a few times greater than the values reported previously by others), low electrical conductivity, and moderate viscosity have been prepared by mixing different particle size grades of materials such as Al2O3, SiC, AlN, Al, and diamond. Effective dispersants, both commercial as well as those synthesized in our laboratory as novel variations of previously known molecular architectures, have been used to facilitate the achievement of these very high loading and stable suspensions.


2015 ◽  
Vol 9 (4) ◽  
Author(s):  
Davide Polito ◽  
Michele Arturo Caponero ◽  
Andrea Polimadei ◽  
Paola Saccomandi ◽  
Carlo Massaroni ◽  
...  

Temperature distribution monitoring in tissue undergoing laser ablation (LA) could be beneficial for improving treatment outcomes. Among several thermometric techniques employed in LA, fiber Bragg grating (FBG) sensors show valuable characteristics, although their sensitivity to strain entails measurement error for patient respiratory movements. Our work describes a solution to overcome this issue by housing an FBG in a surgical needle. The metrological properties of the probes were assessed in terms of thermal sensitivity (0.027 nm °C−1 versus 0.010 nm °C−1 for epoxy liquid encapsulated probe and thermal paste one, respectively) and response time (about 100 ms) and compared with properties of nonencapsulated FBG (sensitivity of 0.010 nm °C−1, response time of 43 ms). The error due to the strain caused by liver movements, simulating a typical respiratory pattern, was assessed: the strain induces a probes output error less than 0.5 °C, which is negligible when compared to the response of nonencapsulated FBG (2.5 °C). The metallic needle entails a measurement error, called artifact, due to direct absorption of the laser radiation. The analysis of the artifact was performed by employing the probes for temperature monitoring on liver undergoing LA. Experiments were performed at two laser powers (i.e., 2 W and 4 W) and at nine distances between the probes and the laser applicator. The artifact decreases with the distance and increases with the power: it exceeds 10 °C at 4 W, when the encapsulated probes are placed at 3.6 mm and 0 deg from the applicator, and it is lower than 1 °C for distance higher than 5 mm and angle higher than 30 deg.


2018 ◽  
Vol 64 ◽  
pp. 02005 ◽  
Author(s):  
Fathi Sanad Mohamed ◽  
Shaker Ahmed ◽  
O. Abdellatif Sameh ◽  
Elmahallawi Iman ◽  
A. Ghali Hani ◽  
...  

A super-passive cooling technique based on a thermal paste is proposed for PV efficiency enhancement in elevated temperature conditions. A mixture between carbon nanotubes and graphene having a promising Seebeck coefficient is chosen. An overall enhancement in efficiency by around 58% was reached while thermoelectrically supplying hundreds of micro-Watt per PV Watt.


2016 ◽  
Vol 138 (1) ◽  
Author(s):  
S. Shanmugan ◽  
O. Zeng Yin ◽  
P. Anithambigai ◽  
D. Mutharasu

All solid-state lighting products produce heat which should be removed by use of a heat sink. Since the two mating surfaces of light emitting diode (LED) package and heat sink are not flat, a thermal interface material (TIM) must be applied between them to fill the gaps resulting from their surface roughness and lack of coplanarity. The application of a traditional TIM may squeeze out when pressure is applied to join the surfaces and hence a short circuit may result. To avoid such a problem, a thin solid film based TIM has been suggested. In this study, a zinc oxide (ZnO) thin film was coated on Cu substrates and used as the TIM. The ZnO thin film coated substrates were used as heat sink purposes in this study. The prepared heat sink was tested with 3 W green LED and the observed results were compared with the results of same LED measured at bare and commercial thermal paste coated Cu substrates boundary conditions. The influence of interface material thickness on total thermal resistance (Rth-tot), rise in junction temperature (TJ), and optical properties of LED was analyzed. A noticeable reduction in Rth-tot (5.92 K/W) as well as TJ (ΔTJ = 11.83 °C) was observed for 800 nm ZnO thin film coated Cu substrates boundary conditions when compared with bare and thermal paste coated Cu substrates tested at 700 mA. Change in TJ influenced the thermal resistance of ZnO interface material. Improved lux level and decreased correlated color temperature (CCT) were also observed with ZnO coated Cu substrates.


2004 ◽  
Vol 831 ◽  
Author(s):  
Y. Xi ◽  
J.-Q. Xi ◽  
Th. Gessmann ◽  
J. M. Shah ◽  
J. K. Kim ◽  
...  

ABSTRACTThe junction temperature of AlGaN/GaN ultraviolet (UV) Light-Emitting Diodes (LEDs) emitting at 295 nm is measured by using the temperature coefficients of the diode forward voltage and emission peak energy. The high-energy slope of the spectrum is explored to measure the carrier temperature. A linear relation between junction temperature and current is found. Analysis of the experimental methods reveals that the diode-forward voltage is the most accurate method (± 3 °C). A theoretical model for the dependence of the diode junction voltage (Vj) on junction temperature (T) is developed that takes into account the temperature dependence of the energy gap. A thermal resistance of 87.6 K/W is obtained with the AlGaN/GaN LED sample mounted with thermal paste on a heat sink.


2017 ◽  
Vol 139 (3) ◽  
Author(s):  
Afroza Nahar ◽  
M. Hasanuzzaman ◽  
N. A. Rahim

Performance of photovoltaic (PV) module decreases significantly with increasing cell temperature due to its overheating. Photovoltaic thermal (PVT) is an optimized technology that facilitates effective removal and utilization of this excess heat leading to enhanced electrical performance. In this article, a 3D numerical model has been developed and analyzed to investigate the PVT performance with a new pancake-shaped flow channel design. This flow channel is attached directly to the backside of PV module by using thermal paste. The governing equations are solved numerically by using Galerkin's weighted residual finite-element method (FEM), which has been developed using COMSOL Multiphysics® software. The numerical results show that the cell temperature reduces on an average 42 °C, and the electrical efficiency and output power increase by 2% and 20 W, respectively, for both aluminum and copper channels with an increase in inlet velocity from 0.0009 to 0.05 m/s. On the other hand, overall efficiency of the PVT system drops about 13% in both cases as the inlet temperature increases from 20 °C to 40 °C. Cell temperature is found to increase approximately by 5.4 °C and 9.2 °C for every 100 W/m2 increase in irradiation level of the PV module with and without cooling system, respectively. Regarding flow channel material, it has been observed that use of either copper or aluminum produces almost similar performance of the PVT module.


2006 ◽  
Vol 977 ◽  
Author(s):  
Ijeoma Nnebe ◽  
Claudius Feger ◽  
Maurice McGlashan-Powell

AbstractThermal pastes are a class of soft composite materials of great importance to the microelectronics industry. The function of these pastes is two-fold: (i) to transport heat away from the chip; and (ii) to accommodate mechanical stresses in the package arising from the mismatch in the thermal expansion between the chip and the heat spreader or sink. Due to the former requirement, thermal pastes are among some of the most highly-filled composite systems in practice (solids volume fraction > 70%). These materials are expected to withstand the significant normal forces, lateral forces, and temperature variations associated with chip operations and power off/on transitions. The structural changes and degradation of various thermal pastes during power cycling have been characterized using optical microscopy and IR thermography. Correlations between the evolving structures and variables such as thermal paste inhomogeneity and binder-particle dispersability have been successfully made and will be presented.


Author(s):  
Yulong Ji ◽  
Gen Li ◽  
Hongbin Ma ◽  
Yuqing Sun

In order to improve thermal interface material (TIM), vertically aligned carbon nanotube (VACNT) arrays were synthesized by the chemical vapor deposition method, and then transferred by dipping in hydrofluoric acid (HF acid) solution to get a free standing VACNT array. Different TIM samples with sandwiched structures were fabricated by inserting the free standing VACNT arrays between two copper plates with and without bonding materials. The laser flash analysis method was applied to measure the overall thermal conductivity of these samples. Results show that: compared with two copper plates in direct contact, thermal conductivity of samples only with VACNT arrays as TIM can be enhanced about 142%–460% depending on the thickness of VACNT arrays. Conventional TIM made up of thermal paste (TG-550 with thermal conductivity of 5 W/mK) and a thermal pad (TP-260 US with thermal conductivity of 6 W/mK) was used as a bonding material between copper plates and VACNT arrays, thermal conductivity has been shown to further improve with the highest values at 8.904 W/mK and 10.17 W/mK corresponding to the different bonding materials and different thicknesses of VACNT arrays used. Results also show that the thicker the VACNT array is when used as a TIM, the lower the overall thermal conductivity of the corresponding samples. This lower thermal conductivity caused by more defects in amorphous carbon of thicker VACNT arrays and lower density of the corresponding sandwiched samples.


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