Computational Model Development and Failure Mode Investigation for a Magnetically-Driven Bearingless Micro-Pump

2017 ◽  
Author(s):  
Gabriel B. Goodwin ◽  
Jesse R. Maxwell ◽  
Triem T. Hoang
Keyword(s):  
Thermal Management ◽  
Computational Study ◽  
Model Development ◽  
Heat Removal ◽  
Heat Pipes ◽  
Space Environment ◽  
Working Fluid ◽  
High Heat Flux ◽  
Loop Heat Pipes ◽  
Micro Pump

As the electronics systems aboard air and spacecraft grow in scale and complexity, so too does the heat generated by those systems. A high-heat flux, compact, maintenance-free cooling system is required to meet the increased demand for heat removal. Loop heat pipes are robust and effective thermal management systems that are long-life and maintenance-free, making them ideal for use in unmanned spacecraft. Integrating a mechanical pump into a loop heat pipe system can drastically improve the system’s heat removal capacity through increased mass flowrate. Like loop heat pipes, magnetically-driven bearingless pumps are also maintenance-free, which is a necessity in the space environment. This work details the modeling of a low-flowrate, magnetically-driven bearingless centrifugal pump and a computational fluid dynamics study of the pump’s operation and performance under a range of conditions that are typical to the demands of a satellite thermal management system. The purpose of this computational study is to investigate the failure mechanism of a bench-test unit that was unable to generate a pressure head with its intended working fluid of ammonia. Model development, validation, and pump performance with multiple working fluids are discussed. The cause of the pump’s failure is investigated.

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.

scholarly journals Experimental Study on Thermal Performance of a Loop Heat Pipe with Different Working Wick Materials

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2453
Author(s):  
Kyaw Zin Htoo ◽  
Phuoc Hien Huynh ◽  
Keishi Kariya ◽  
Akio Miyara
Keyword(s):  
Stainless Steel ◽  
Heat Pipes ◽  
Working Fluid ◽  
Stable Operation ◽  
Loop Heat Pipe ◽  
Heater Surface ◽  
Loop Heat Pipes ◽  
Limited Temperature ◽  
Sintered Stainless Steel ◽  
Continuous Heat

In loop heat pipes (LHPs), wick materials and their structures are important in achieving continuous heat transfer with a favorable distribution of the working fluid. This article introduces the characteristics of loop heat pipes with different wicks: (i) sintered stainless steel and (ii) ceramic. The evaporator has a flat-rectangular assembly under gravity-assisted conditions. Water was used as a working fluid, and the performance of the LHP was analyzed in terms of temperatures at different locations of the LHP and thermal resistance. As to the results, a stable operation can be maintained in the range of 50 to 520 W for the LHP with the stainless-steel wick, matching the desired limited temperature for electronics of 85 °C at the heater surface at 350 W (129.6 kW·m−2). Results using the ceramic wick showed that a heater surface temperature of below 85 °C could be obtained when operating at 54 W (20 kW·m−2).

Active and passive cooling technologies for thermal management of avionics in helicopters: Loop heat pipes and mini-Vapor Cycle System

2018 ◽  
Vol 5 ◽  
pp. 107-116 ◽  
Author(s):  
Claudio Zilio ◽  
Giulia Righetti ◽  
Simone Mancin ◽  
Romain Hodot ◽  
Claude Sarno ◽  
...  
Keyword(s):  
Thermal Management ◽  
Heat Pipes ◽  
Passive Cooling ◽  
Loop Heat Pipes ◽  
Cycle System

Thermal Management of a Heat-Pipe Drill: A FEM Analysis

2003 ◽  
Author(s):  
Tien-Chien Jen ◽  
Rajendra Jadhav
Keyword(s):  
Finite Element ◽  
Heat Pipe ◽  
Thermal Management ◽  
Heat Pipes ◽  
High Heat ◽  
Heat Fluxes ◽  
High Heat Flux ◽  
Drilling Process ◽  
Generation Process ◽  
Finite Element Software

Thermal management using heat pipes is gaining significant attention in past decades. This is because of the fact that it can be used as an effective heat sink in very intricate and space constrained applications such as in electronics cooling or turbine blade cooling where high heat fluxes are involved. Extensive research has been done in exploring various possible applications for the use of heat pipes as well as understanding and modeling the behavior of heat pipe under those applications. One of the possible applications of heat pipe technology is in machining operations, which involves a very high heat flux being generated during the chip generation process. Present study focuses on the thermal management of using a heat pipe in a drill for a drilling process. To check the feasibility and effectiveness of the heat pipe drill, structural and thermal analyses are performed using Finite Element Analysis. Finite Element Software ANSYS was used for this purpose. It is important for any conceptual design to be made practical and hence a parametric study was carried out to determine the optimum geometry size for the heat pipe for a specific standard drill.

scholarly journals Simulation of the thermal control system of nanosatellite using the loop heat pipes under the orbital flight conditions

2021 ◽  
Vol 22 (1) ◽  
pp. 23-35
Author(s):  
Yu Wang ◽  
Oleg V. Denisov ◽  
Liliana V. Denisova
Keyword(s):  
Control System ◽  
Thermal Regime ◽  
Thermal Power ◽  
Heat Removal ◽  
Heat Pipes ◽  
Thermal Control ◽  
Thermal Design ◽  
Loop Heat Pipes ◽  
Thermal Control System ◽  
Design Power

One of the key problems in the development of nanosatellites is to provide a given temperature range for the operation of the on-board computer. The constantly increasing information load leads to the need to use more advanced processors with high thermal design power (TDP). The indicated thermal regime of processors can be achieved using remote heat removal systems - miniature loop heat pipes. Using a model of nanosatellite as an example, a thermal control system with miniature loop heat pipes is designed. The simulation was carried out in the Siemens NX program in the elliptical and geostationary orbits of the Earth. The cooling schemes of the processor with a thermal power of 15 W using one and two loop heat pipes are considered. Calculations showed that the use of loop heat pipes can reduce the processor temperature to acceptable values. The anisotropy of the thermal conductivity coefficient in the reinforcement plane of the composite material of the nanosatellite case can have a significant effect on the temperature of the processor. This opens up prospects for the use of anisotropic composite materials to ensure the thermal regime of the nanosatellite.

Steady State Parametric Modeling of Non-Conventional Loop Heat Pipes

2013 ◽  
Author(s):  
Karthik S. Remella ◽  
Frank M. Gerner ◽  
Ahmed Shuja
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Steady State ◽  
Transfer Coefficient ◽  
Thermal Energy ◽  
Heat Pipes ◽  
Parametric Model ◽  
Parametric Modeling ◽  
Working Fluid ◽  
Loop Heat Pipes

Loop Heat Pipes (LHPs) are used in many thermal management applications, especially for micro-electronics cooling, because of their ability to passively transport thermal energy from a source to a sink. This paper describes the development of a parametric model for a non-conventional LHP operating in steady state, employed to cool Light Emitting Diodes (LEDs). This device is comprised of a flat evaporator, and a finned circular loop wherein condensation and sub-cooling of the working fluid takes place. Unlike a conventional LHP, this device has no compensation chamber. In the mesh screen of the evaporator, the vapor flow entrains liquid and hence the quality of the two-phase mixture leaving the evaporator (xevap) is less than unity (unlike in a conventional LHP where saturated vapor leaves the evaporator). Since this lower quality (approximately 0.2) results in a smaller ratio of latent energy to sensible energy being removed by the condenser and sub-cooler respectively; the ratio of the length of the sub-cooler to condenser length is significantly larger. This results in more stable and controlled operation of the device. Mathematical models of the evaporator, the condenser and the sub-cooler sections are developed, and two closure conditions are employed in this model. For consistency and accuracy, some parameters in the model, such as the natural convection heat transfer coefficient (h o) and a few thermal resistances in the evaporator, are estimated empirically from test data on the device. The empirically obtained value of the heat transfer coefficient is in very good agreement with correlations from the literature. The parametric model accurately predicts the LED board temperature and other temperatures for a specific amount of thermal energy dissipated by the LEDs.

Heat Management With Phase Change of Self-Rewetting Fluids

2005 ◽  
Author(s):  
Yoshiyuki Abe
Keyword(s):  
Surface Tension ◽  
Phase Change ◽  
Thermal Management ◽  
Heat Pipes ◽  
Working Fluid ◽  
Reduced Gravity ◽  
Heat Management ◽  
Preliminary Experimental Data ◽  
Marangoni Effects ◽  
Dry Spot

The present paper mainly describes the latest progress in the thermal management devices with using “self-rewetting fluids” as a working fluid. The self-rewetting fluids are those dilute aqueous solutions of high carbon alcohols, which show a particular surface tension behavior—an increase in the surface tension with increasing temperature. In the case of phase change of these particular solutions, the Marangoni effects caused by both temperature gradient and concentration gradient along vapor/liquid interface are expected to induce a strong liquid inflow to local hot or dry spot at heater wall. Such a behavior is more pronounced in reduced gravity conditions and micro-scale heat transfer. The paper contains a series of reduced gravity and terrestrial experimental results on thermal management devices with self-rewetting fluids, wickless heat pipes and wicked heat pipes in reduced gravity and terrestrial conditions, respectively. In addition, preliminary experimental data for pool boiling characteristics of self-rewetting fluids are given.

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