Thermal Performance of a Mini Liquid-Cooled Cold Plates for Robot Cooling

Author(s):  
Sarng Woo Karng ◽  
Kyudae Hwang ◽  
Jongmin Moon ◽  
Seo Young Kim

Thermal performance for mini water-cooled cold plates covered with non-metallic polycarbonate (PC) is experimentally measured in this study. The mini cold plates are designed to reduce the overall weight of the cooling device for effective heat dissipation from a humanoid robot. The water-cooled cold plate has a 10×10 mm2 of base plate which is made of copper or aluminum. Two different types of enhanced surfaces are considered in the present study: copper pin-finned surface of 0.5×0.5 mm2 area and 1.5 mm high with 0.5 mm fin spacing and aluminum foam-finned surface of 92% porosity and 40 PPI (pores per inch). Heat transfer rates are measured according to the input power and the flow rate of cooling water. The surface temperature of the base plate and the cooling water temperatures at inlet and outlet of each cold plate are measured. From the results, it is found that the copper pin-finned cold plate shows better performance than the aluminum foam-finned cold plate in terms of thermal resistance and pressure drop.

Author(s):  
Nikhil Lakhkar ◽  
Madhusudan Iyengar ◽  
Michael Ellsworth ◽  
Dereje Agonafer

With the continuing industry trends towards smaller, faster and higher power devices, thermal management has become an extremely important element in the development of computer products. The primary goal of a good thermal design is to ensure that the chip can function at its rated frequency, while maintaining its junction temperature below the specified limit, to ensure reliable operation. The use of a heat sink or cold plate to manage the external thermal resistance has been well documented in the literature. However, the measurement of thermal performance of today state-of-the-art cold plates is challenging because of the low value of thermal resistance that they offer to heat dissipation. In this paper, the design of a tester apparatus for such high performance cold plates is presented. The expected performance of the tester is modeled numerically for a heat flux of 250 W/cm2, and for a range of footprint areas of 100-400 mm2. The analysis study is supported by a detailed uncertainty analysis that utilizes a Monte Carlo simulation approach. It was observed that the sum of random and repeatable errors could be controlled to within ±7.5% even for a very high performance cold plate with an effective heat transfer coefficient of 200,000 W/m2-K dissipating 250 W/cm2, with assumed errors in other relevant parameters.


Author(s):  
Sarng Woo Karng ◽  
Suk Won Lee ◽  
Kyudae Hwang ◽  
Seo Young Kim

In this study, we compare thermal performance between one metallic cold plate and three different types of non-metallic cold plates for humanoid robot cooling. The four types of cold plates have the same dimension of 20×20 mm2 base area with 7 mm high. A metallic cold plate is made of copper. Three non-metallic PC (polycarbonate) cold plates, which are designed to reduce the overall weight of robot cooling system, are composed of a polycarbonate cover with three different base shapes. All cold plates are mounted on a 20×20 mm2 copper heating block with two cartridge heaters of 30 W/cm2. The overall heat transfer coefficients per unit mass and thermal resistances are obtained for the liquid-cooled cold plates. It is interesting to note that the PC cold plate with an aluminum base plate with 18 channels shows the best heat transfer performance per unit mass. Most polycarbonate cold plates display fairly comparable thermal performance with more reduced weight compared to a conventional copper cold plate.


Author(s):  
Yi. Feng ◽  
Y. Wang ◽  
C. Y. Huang

The increasing power consumption of microelectronic systems and the dense layout of semiconductor components leave very limited design spaces with tight constraints for the thermal solution. Conventional thermal management approaches, such as extrusion, fold-fin, and heat pipe heat sinks, are somehow reaching their performance limits, due to the geometry constraints. Currently, more studies have been carried out on the liquid cooling technologies, as the flexible tubing connection of liquid cooling system makes both the accommodation in constrained design space and the simultaneous cooling of multi heating sources feasible. To significantly improve the thermal performance of a liquid cooling system, heat exchangers with more liquid-side heat transfer area with acceptable flow pressure drop are expected. This paper focuses on the performance of seven designs of source heat exchanger (cold plate). The presented cold plates are all made in pure copper material using wire cutting, soldering, brazing, or sintering process. Enhanced heat transfer surfaces such as micro channel and cooper mesh are investigated. Detailed experiments have been conducted to understand the performance of these seven cooper cold plates. The same radiators, fan, and water pump were connected with each cooper cold plate to investigate the overall thermal performance of liquid cooling system. Water temperature readings at the inlets and outlets of radiators, pump, and colder plate have been taken to interpret the thermal resistance distribution along the cooling loop.


Author(s):  
T. J. Lu ◽  
D. Sui ◽  
T. Kim ◽  
M. L. Xu

The challenge in thermal management is the capability to remove heat from the device while maintaining acceptable component operating temperatures. Metal foams with high porosity ε∼0.9 have in recent years emerged as a promising heat dissipation medium, due to high extended surface area densities as well as tortuous flow passages that promote the coolant flow mixing. This study focuses on investigating experimentally the thermal performance of highly porous aluminum foam heat sinks with open cells under the impingement of axial fan flows. While the porosity, foam thickness and axial fan rotation are fixed, three selected pore densities and varying impinging distance are considered. The parameters of overall thermal resistance Rθ and temperature difference ΔT are used to evaluate thermal performance of aluminum foam heat sink which is also compared with that of a conventional fin heat sink. The experimental results represent aluminum foam heat sinks can provide similar or better cooling performance with more compact (a 50% reduction in both the weight and volume) than conventional fin heat sink.


2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Peng Wang ◽  
Patrick McCluskey ◽  
Avram Bar-Cohen

Recent trends including rapid increases in the power ratings and continued miniaturization of semiconductor devices have pushed the heat dissipation of power electronics well beyond the range of conventional thermal management solutions, making control of device temperature a critical issue in the thermal packaging of power electronics. Although evaporative cooling is capable of removing very high heat fluxes, two-phase cold plates have received little attention for cooling power electronics modules. In this work, device-level analytical modeling and system-level thermal simulation are used to examine and compare single-phase and two-phase cold plates for a specified inverter module, consisting of 12 pairs of silicon insulated gate bipolar transistor (IGBT) devices and diodes. For the conditions studied, an R134a-cooled, two-phase cold plate is found to substantially reduce the maximum IGBT temperature and spatial temperature variation, as well as reduce the pumping power and flow rate, in comparison to a conventional single-phase water-cooled cold plate. These results suggest that two-phase cold plates can be used to substantially improve the performance, reliability, and conversion efficiency of power electronics systems.


2021 ◽  
Vol 39 (1A) ◽  
pp. 34-44
Author(s):  
Talib Z. Farge ◽  
Samar J. Ismael ◽  
Rawad M. Thyab

The present work investigated the thermal performance of thermosyphon by using distilled water as a working fluid at different filling ratios (50%, 60%, and 70 %). The thermosyphon was manufactured from a copper tube with outer and inner diameters (26 and 24) mm, respectively. The thermosyphon was tested experimentally at different input power (100, 200 and 300) Watt. The operating temperature of the oil was chosen below 85°C. Experimental results revealed that the filling ratio of 60% exhibited the best heat dissipation at the highest operating temperature. While the low operating temperature and 50 % filling ratio show better heat dissipation. Further, it was found that the thermal resistance of the thermosyphon was obviously decreased with increasing the input power. The percentage decrease in the thermal resistance of the thermosyphon at a filling ratio of 0.6 was 14.6 % compared with that filling ratio of 0.5 at an input power of 300 W.


Batteries ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 17
Author(s):  
Seyed Saeed Madani ◽  
Erik Schaltz ◽  
Søren Knudsen Kær

Thermal analysis and thermal management of lithium-ion batteries for utilization in electric vehicles is vital. In order to investigate the thermal behavior of a lithium-ion battery, a liquid cooling design is demonstrated in this research. The influence of cooling direction and conduit distribution on the thermal performance of the lithium-ion battery is analyzed. The outcomes exhibit that the appropriate flow rate for heat dissipation is dependent on different configurations for cold plate. The acceptable heat dissipation condition could be acquired by adding more cooling conduits. Moreover, it was distinguished that satisfactory cooling direction could efficiently enhance the homogeneity of temperature distribution of the lithium-ion battery.


Author(s):  
Zhuo Cui

This paper presents the effects of heat dissipation performance of pin fins with different heat sink structures. The heat dissipation performance of two types of pin fin arrays heat sink are compared through measuring their heat resistance and the average Nusselt number in different cooling water flow. The temperature of cpu chip is monitored to determine the temperature is in the normal range of working temperature. The cooling water flow is in the range of 0.02L/s to 0.15L/s. It’s found that the increase of pin fins in the corner region effectively reduce the temperature of heat sink and cpu chip. The new type of pin fin arrays increase convection heat transfer coefficient and reduce heat resistance of heat sink.


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.


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