4. Dissipation—Power—Transcendence / Heidegger

Performance investigation of oil journal bearings is of particular importance given the growing use of them as a support for rotary components in a wide range of industrial machines. Frictional forces and shear stresses, which are proportionate to the velocity of lubricating layers at different points in the bearing space, provide the basis for changing temperature conditions. Various factors such as rotational velocity increase, slip width reduction, and small heat transfer coefficient of lubricant cause intensification of lubricant temperature changes. In the present study, with using computational fluid dynamic (CFD) thermohydrodynamic (THD) numerical simulations, the effect of nanoparticles on the performance features of plain journal bearings is evaluated. Particularly, 3D simulation of a journal bearing is implemented using CFD which considerably improves the accuracy of results, coupled with conjugate heat transfer model for metal parts of bearings. Reynolds equation model is used to calculate the oil-film pressure developed in hydrodynamic journal bearings by applying the nano-based lubricants. The configuration of thrust bearing consists of six pads in this study. In order to reduce the modeling complexity and computational cost and because of the symmetrical geometry of the pads, simulation of a single pad is considered instead of the entire domain. In this study, TiO2 nanoparticle with different volume fraction percentages are used. The parameters that are changed to evaluate the performance of the bearing include volume fraction percentage of the nanoparticle, type of lubricant, and rotational speed. Based on the results, for all different lubricant types, the dissipation power, average shear stress, and temperature rise are increased with augmenting the rotational speed. By increasing the rotational speed from 500 to 1500 rpm, the average shear stress increases by more than 100%, 120%, and 130% for DTE 26, DTE 25, and DTE 24 lubricant types, respectively. Moreover, by increasing the rotational speed from 500 to 1500 rpm, the dissipation power, and temperature rise are increased around 600% and 800%, respectively. Furthermore, increasing nanoparticles volume fraction from 0% to 10%, increases all parameters by approximately 10% for all lubricant types and in all rotational speeds.

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Mathematical Simulations and On-Road Experimentations of the Vibration Energy Harvesting from Mining Dump Truck Hydro-Pneumatic Suspension

Shock and Vibration ◽

10.1155/2019/4814072 ◽

2019 ◽

Vol 2019 ◽

pp. 1-16 ◽

Cited By ~ 1

Author(s):

Wenguang Wu ◽

Sha Zhang ◽

Zhiyong Zhang

Keyword(s):

Energy Harvesting ◽

Vibrational Energy ◽

Average Power ◽

Open Pit ◽

Dissipated Energy ◽

Dump Truck ◽

Oil Consumption ◽

Vibration Energy Harvesting ◽

Pneumatic Suspension ◽

Dissipation Power

Running on an unpaved road, the truck’s vibration is weakened by the HPS (hydro-pneumatic suspension) and transformed into thermal energy which was finally dissipated in the air. This paper is aimed to discuss the energy harvesting potential from the truck HPS on random road excitation. In this manner, a quarter-truck model was built and the kinetic energy method that can be used to calculate the power of the dissipated energy was proposed. The dissipated instantaneous power (The peak value is 180 kW) and average power (12 kW) were analyzed which showed 15-fold of difference. The different road class analysis results showed that the E-class road excited 4-fold of power than that of D-class road. The influence of damping and stiffness on the dissipation power was analyzed. The results showed that the power excited by the D-class road is less sensitive than the E-class road. Furthermore, it is interesting that the results also show that the value of average dissipated power when running on E-class road is very close to the speed value, respectively. The real road test of the truck was carried out in an open pit mine and verified the simulation results. The final results demonstrated that the vibrational energy that harvested from the HPS could reduce oil consumption by about 4% in theory.

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Jet Impingement Cooling of an Inverter Module in the Harsh Environment of a Hybrid Vehicle

Heat Transfer: Volume 4 ◽

10.1115/ht2005-72574 ◽

2005 ◽

Cited By ~ 6

Author(s):

Avijit Bhunia ◽

Chung-Lung Chen

Keyword(s):

Heat Dissipation ◽

Jet Impingement ◽

Base Plate ◽

Hybrid Vehicle ◽

System Level ◽

Liquid Jet ◽

Harsh Environment ◽

Impingement Cooling ◽

Dissipation Power ◽

Cooling Technique

This paper presents a study of liquid jet impingement cooling technique and its system level implementation for thermal management of an inverter module in a hybrid vehicle. Clusters of anti-freeze liquid jet array impinge on the base plate of a 450V (DC Link voltage)/400A (RMS current) module, made by Semikron, Inc. In the harsh environment of an automobile, the ambient temperature of the coolant is 105°C, and the maximum allowable flow rate and pressure drop are 2.5GPM and 1.6bar respectively. The impingement cooling technique demonstrates 1623 Watts of heat dissipation for 20°C device temperature rise above ambient. This translates to a chip level dissipation power density of 56W/cm2, approximately 1.8X improvement over forced convection liquid cooling in the state-of-the-art pin fin cold plate. At the highest power, the less than 3°C temperature variation among the twelve IGBT measurements indicates a high degree of reliability in module operation. The efficient phase change heat transfer mechanism sets in at local base plate temperatures between 109–111°C, which accounts for more than 10% of the total heat dissipation at 1600W level.

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Evaluation on the analogy between the dynamic magnetosphere and a forced and/or self-organized critical system

Nonlinear Processes in Geophysics ◽

10.5194/npg-9-399-2002 ◽

2002 ◽

Vol 9 (5/6) ◽

pp. 399-407 ◽

Cited By ~ 5

Author(s):

A. T. Y. Lui

Keyword(s):

Solar Wind ◽

Power Law ◽

Plasma Sheet ◽

Critical State ◽

Conclusive Evidence ◽

Critical System ◽

Scale Free ◽

Self Organized ◽

Dissipation Power ◽

Different Levels

Abstract. The dissipation power and size of auroral blobs are investigated in detail to examine the possible analogy between the dynamic magnetosphere and a forced and/or self-organized critical system. The distributions of these auroral parameters are sorted in terms of different levels of activity, namely substorms, pseudo-breakups, and quiet conditions. A power law (scale-free) component is seen in all these distributions. In addition, a peak distribution is found for substorm intervals and a hump for pseudo-breakup intervals. The peak distribution is present prominently during magnetic storms, i.e. when the magnetosphere is strongly driven by the solar wind. It is interpreted that the scale-free component is associated with the activity of the diffuse aurora, corresponding to disturbances at all permissible scales within the plasma sheet. Ionospheric feedback appears to be essential for the presence of two components in the distribution for auroral dissipation power. These results are consistent with the concept that the magnetosphere is in a forced and/or self-organized critical state, although they do not constitute conclusive evidence for the analogy.

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Analysis of Dissipation Power from Multi-State Switchable Damper

International Journal of Vehicle Structures and Systems ◽

10.4273/ijvss.13.1.14 ◽

2021 ◽

Vol 13 (1) ◽

Author(s):

M.M.M. Salem ◽

Mostafa M. Makrahy ◽

M.R. Abd-El-Wahhab ◽

Abd Allah S. Sharkawy

Keyword(s):

Linear Relationship ◽

Experimental Test ◽

Power Dissipation ◽

Vehicle Dynamics ◽

Vibration Energy ◽

Test Results ◽

Laboratory Environment ◽

Suspension Systems ◽

Energy Dissipated ◽

Dissipation Power

A considerable amount of vibration energy in automotive is worth of being harvested through power dissipation using regenerative suspension systems. In this study, the vehicle dynamics and energy dissipated from a Multi-State Switchable Damper (MSSD) based suspension for various vibration dynamic modes are assessed. Quantification of the energy dissipated in a MSSD is achieved through an experimental test at laboratory environment. The test results showed a linear relationship between the dissipated power and the damping modes.

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