scholarly journals Fluid Choice Based on Thermal Model and Performance Testing for Direct Cooled Electric Drive

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5867
Author(s):  
Robert Lehmann ◽  
Arthur Petuchow ◽  
Matthias Moullion ◽  
Moritz Künzler ◽  
Christian Windel ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Model ◽  
Performance Testing ◽  
Sensitivity Study ◽  
Maximum Heat ◽  
Cooling Fluid ◽  
Two Fluids ◽  
Fluid Properties ◽  
And Performance ◽  
Electric Traction

In this publication, the cooling fluid for direct oil-cooled electric traction drive is investigated. A dedicated thermal resistance model was developed in order to show the influence of the fluid properties on the continuous performance. For this purpose, the heat transfer parameters are adjusted in the simulation using an exponential approach in order to evaluate the cooling fluid. In a sensitivity study, density, heat capacity, thermal conductivity, and viscosity are investigated. Because viscosity, within the range investigated, shows the largest percentage deviation from the reference fluid, the greatest effect on performance can be seen here. In order to check the plausibility of the calculated results of the thermal simulation, two fluids were chosen for performance testing on a dedicated electro motor cooling (EMC) test. Beyond the investigation of heat transfer, aging of the defined fluid at maximum heat input over several hours is also evaluated. Only slight changes of the fluid properties are detected. This publication presents a thermal model for direct oil-cooled drive trains, which consider fluid properties. Furthermore, the model was tested for plausibility on real hardware.

scholarly journals Topology design of two-fluid heat exchange

2020 ◽  
Author(s):  
Hiroki Kobayashi ◽  
Kentaro Yaji ◽  
Shintaro Yamasaki ◽  
Kikuo Fujita
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Heat Transfer Rate ◽  
Design Variable ◽  
Pressure Loss ◽  
Transfer Rate ◽  
Maximum Heat ◽  
Variable Field ◽  
Two Fluids ◽  
Two Fluid

Abstract Heat exchangers are devices that typically transfer heat between two fluids. The performance of a heat exchanger such as heat transfer rate and pressure loss strongly depends on the flow regime in the heat transfer system. In this paper, we present a density-based topology optimization method for a two-fluid heat exchange system, which achieves a maximum heat transfer rate under fixed pressure loss. We propose a representation model accounting for three states, i.e., two fluids and a solid wall between the two fluids, by using a single design variable field. The key aspect of the proposed model is that mixing of the two fluids can be essentially prevented. This is because the solid constantly exists between the two fluids due to the use of the single design variable field. We demonstrate the effectiveness of the proposed method through three-dimensional numerical examples in which an optimized design is compared with a simple reference design, and the effects of design conditions (i.e., Reynolds number, Prandtl number, design domain size, and flow arrangements) are investigated.

Static configuration of liquid films on horizontal tubes with low radial fins: implications for condensation heat transfer

1987 ◽  
Vol 410 (1838) ◽  
pp. 125-139 ◽  
Keyword(s):  
Heat Transfer ◽  
Liquid Films ◽  
Finned Tube ◽  
Tube Surface ◽  
Maximum Heat ◽  
Finned Tubes ◽  
Horizontal Tubes ◽  
Maximum Heat Transfer ◽  
Fluid Properties ◽  
Static Conditions

The configuration of a liquid film retained by surface tension forces on horizontal low-finned tubes has been analysed. It has been shown that liquid is retained on the upper parts of the tube surface previously regarded as 'unflooded'. The meniscus in a radial plane has been shown to approximate to a circular arc, with radius dependent only on the distance from the bottom of the tube, fluid properties and gravity. Four ‘flooding’ conditions are identified for trapezoidal-section fins and the positions around a tube at which these occur have been determined. Experimental measurements, for condensation of three fluids on tubes with rectangular-section fins, suggest that maximum heat-transfer en­hancement occurs when the spacing between the fins (the only geometric variable in these tests) is such as to maximize the ‘unblanked’ (by retained liquid under static conditions) finned tube surface area. The ‘unblanked’ or ‘active’ area is increased by using a radiused fillet at the fin root rather than a sharp corner. This might also be expected to give a corresponding increase in heat-transfer enhancement during condensation.

Thermal Properties of Graphite Foam: Experiments and Modeling

Volume 1 ◽  
2004 ◽  
Author(s):  
N. Yu ◽  
C. C. Tee ◽  
H. Li
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Mesophase Pitch ◽  
Cooling Fluid ◽  
Open Cell ◽  
Manufacturing Technique ◽  
Fluid Properties ◽  
Transfer Properties ◽  
Graphite Foam

Mesophase pitch-derived open-cell graphite foams with excellent heat transfer properties have been developed by using a relatively simple manufacturing technique [1]. The specific thermal conductivity of the graphite foam is more than seven times greater than that of copper and six times greater than that of aluminum. The present work focuses on the interactions between the effective heat transfer properties and foam microstructure, temperature, and cooling fluid properties.

Thermal-Field Experimental Study of a Thin Circular Carbon-Fiber Tube in Stratosphere Environment

2011 ◽  
Vol 189-193 ◽  
pp. 1027-1030
Author(s):  
Fen Bo Pei ◽  
Guo Quan Tao ◽  
Zhe Wu
Keyword(s):  
Heat Transfer ◽  
Thermal Model ◽  
Thermal Field ◽  
Thermal State ◽  
Radiant Heat ◽  
Radiant Heat Transfer ◽  
The Sun ◽  
Coupling Problem ◽  
Whole Process ◽  
And Performance

The changeable, atrocious environment of stratosphere affects the capability and performance of the structure. An effective and economical approach used to analyze thermal state of stratospheric aerostat was investigated in this study. A simplified thermal model was built in environmental experiment which simulates stratosphere and takes radiation of the sun, air and earth. This model solved a coupling problem of heat conduction, heat convection and radiant heat transfer and obtained a pleasant result through numerical simulations of Fluent. The whole process makes great effect to further analysis and study of stratospheric structure.

Cylindricity Sensitivity Thermal Model of the AGR-5/6/7 Experiment in the Advanced Test Reactor

2020 ◽  
Author(s):  
Grant L. Hawkes
Keyword(s):  
Heat Transfer ◽  
Stainless Steel ◽  
Thermal Model ◽  
National Laboratory ◽  
Sensitivity Study ◽  
Operating Conditions ◽  
Department Of Energy ◽  
Easy Method ◽  
Gas Gap ◽  
Test Reactor

Abstract The AGR-5/6/7 experiment is currently being irradiated in the Advanced Test Reactor (ATR) at the Idaho National Laboratory and is approximately 70% complete. Several fuel and material irradiation experiments have been planned for the U.S. Department of Energy Advanced Gas Reactor Fuel Development and Qualification Program, which supports the development and qualification of tristructural isotropic (TRISO)-coated particle fuel for use in high-temperature gas-cooled reactors. The goals of these experiments are to provide irradiation performance data to support fuel process development, qualify fuel for normal operating conditions, support development of fuel performance models and codes, and provide irradiated fuel and materials for post-irradiation examination and safety testing. Originally planned and named as separate fuel experiments, but subsequently combined into a single test train, AGR-5/6/7 is testing low-enriched uranium oxycarbide TRISO fuel. The AGR-5/6/7 test train has five capsules with thermocouples and independent gas control mixtures. Unique to this paper is a sensitivity study concerning the cylindricity of the graphite holders containing the fuel compacts and their eccentricity in relation to the stainless-steel capsule walls. Each capsule has small nubs on the outside used for centering the graphite holder inside the stainless-steel capsule with a small gas gap used to control temperature. Due to machining tolerances of these nubs, and vibration wearing the nubs down when the experiment is running in the reactor, the possibility exists that the holder may move around radially. Each capsule is equipped with several thermocouples placed at various radii and depths within each graphite holder. This paper will show the sensitivity of offsetting the graphite holder for various radii in 45-degree increments around the circle with the objective of minimizing the difference between the measured thermocouples and the modeled thermocouple temperatures. Separate gas mixtures of helium/neon are introduced into this gas gap between the holder and capsule wall and changed as necessary to maintain the desired thermocouple temperatures to keep the fuel compacts at a constant temperature as the nuclear reactor conditions change. The goal of the sensitivity study is to find a radius and an angle to offset the holder from perfectly centered for each of the five capsules separately. The complex thermal model includes fission heating, gamma heating, radiation heat transfer, and heat transfer via conduction and radiation across the control gaps. Subroutines linked to the thermal model offer an easy method to offset the graphite holder from the capsule walls without remeshing the entire model.

Correlation for Prediction of Peak Heat Flux Achieved With a Bi-Porous Wick

2009 ◽  
Author(s):  
Ladan Amouzegar ◽  
Ivan Catton ◽  
Aleksander Vadnjal
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Material Properties ◽  
Working Fluid ◽  
Maximum Heat ◽  
Porous Wick ◽  
Maximum Heat Transfer ◽  
Capillary Limit ◽  
Small Pore ◽  
Fluid Properties

In the past researchers noted three distinct stages of evaporative heat transfer in a bi-porous wick. The maximum heat transfer rate is postulated to occur at the end of the second stage when the maximum number of small pores interfaces the vapor space. For optimization purposes a reliable model that relates the maximum heat flux of a bi-porous wick to the wick material properties, wick geometry given with average large and small pore diameter, wick thickness, and working fluid properties is demanded. In this work, a semi-empirical model that relates the heat flux at the capillary limit to the wick material properties, working fluid properties and wick dimensions is further developed. The model is based on the hydrodynamics of the capillary limit. The result is employed to qualitatively and quantitatively optimize the wick parameters for some specific cases and the optimization can be further performed using the proposed model.

Digitalization system of ancient architecture decoration art based on neural network and image features

2020 ◽  
pp. 1-12
Author(s):  
Wu Xin ◽  
Qiu Daping
Keyword(s):  
Neural Network ◽  
Construction Industry ◽  
Three Dimensional ◽  
Performance Testing ◽  
Image Features ◽  
Three Dimensional Model ◽  
Performance Effect ◽  
Data Process ◽  
And Performance ◽  
Construction Mode

The inheritance and innovation of ancient architecture decoration art is an important way for the development of the construction industry. The data process of traditional ancient architecture decoration art is relatively backward, which leads to the obvious distortion of the digitalization of ancient architecture decoration art. In order to improve the digital effect of ancient architecture decoration art, based on neural network, this paper combines the image features to construct a neural network-based ancient architecture decoration art data system model, and graphically expresses the static construction mode and dynamic construction process of the architecture group. Based on this, three-dimensional model reconstruction and scene simulation experiments of architecture groups are realized. In order to verify the performance effect of the system proposed in this paper, it is verified through simulation and performance testing, and data visualization is performed through statistical methods. The result of the study shows that the digitalization effect of the ancient architecture decoration art proposed in this paper is good.

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