Purpose – Current lubrication analyses of misaligned journal bearings were generally performed under some given preconditions. To make the lubrication analysis closer to the actual situation and usable to the journal bearing design, the purpose of this paper was to calculate the lubrication characteristics of misaligned journal bearings considering the viscosity-pressure effect of the oil, the surface roughness and the elastic deformation of the journal bearing at the same time. Design/methodology/approach – The lubrication of bearings was analyzed using the average Reynolds equation. The deformation of the bearing surface under oil film pressure was calculated by a compliance matrix method. The compliance matrix was established by finite element analysis of the bearing housing. The viscosity-pressure and viscosity–temperature equations were used in the analysis. Findings – The oil viscosity-pressure relationship has a significant effect on the lubrication of misaligned journal bearings. The surface roughness will affect the lubrication of misaligned journal bearings when the eccentricity ratio and angle of journal misalignment are all large. The directional parameter of the surface has an obvious effect on the lubrication of misaligned journal bearings. The deformation of the bearing surface has a remarkable effect on the lubrication of misaligned journal bearings. Originality/value – The lubrication characteristics of misaligned journal bearings were calculated considering the viscosity-pressure effect of the oil, the surface roughness and the elastic deformation of the journal bearing at the same time. The results of this paper are helpful to the design of the bearing.
The current experimental researches on the orbit of a journal center of a crankshaft bearing for an internal combustion engine were usually focused on the 2D movement locus of a crankshaft journal center in the cross section of the bearing. However, in the actual operation of an internal combustion engine, there exists the movement of a crankshaft journal along the bearing axis under the effect of various factors, such as the crankshaft deformation acted by load. Obviously the tribological performance of a crankshaft bearing is affected inevitably by the movement of the crankshaft journal along the bearing axis. In this paper, a four-stroke four-cylinder internal combustion engine was taken as the studying object, the 3D orbit (that includes the movement in the cross section of the bearing and the movement along the bearing axis) of the journal center of the crankshaft bearing for an internal combustion engine was measured under a number of operating conditions on the test bench of an internal combustion engine. The position of the journal in the crankshaft bearing was obtained by the measurement using eddy current gap sensors and the data post-process. The results show that there exists the movement of the crankshaft journal along the axial direction in the bearing for an internal combustion engine. The actual orbit of the journal center of the crankshaft bearing for an internal combustion engine is a 3D spatial curve. The orbit of the journal center of the crankshaft bearing in one operating cycle of an internal combustion engine is not a closed curve. There is relatively a large movement of the journal along the axial direction of the crankshaft bearing, and the numerical value of the movement is greater than the radial clearance of the bearing. The greater the rotational speed of the internal combustion engine, the larger the amount of axial movement of the journal. The periodic variation exists in the axial movement of the bearing journal in one operating cycle of the internal combustion engine at low engine speed, and the varying periodicity equals the number of engine cylinders. There is no obvious varying rule of the axial movement of the bearing journal in one operating cycle of the internal combustion engine at high engine speed.
Energy storage system (ESS) provides a new way to solve the imbalance between supply and demand of power system caused by the difference between peak and valley of power consumption. [1][2][3] Compared with various energy storage technologies, the container storage system has the superiority of long cycle life, high reliability, and strong environmental adaptability, which attracts more and more attention. 4,5 The ESS has some vertical racks, equipped with a battery management system, a heating ventilation air conditioning system, and a fire detection and suppression system. 6,7 Unfortunately, there were many energy storage battery fires in previous years. 8-10 A Korean government report indicated that a significant factor in the cause of the fires was the thermal runaway of batteries. 11 Therefore, a well-designed battery thermal management system (BTMS) is highly needed. [12][13][14] It has been found that air cooling is currently the most widely used cooling method due to its low manufacturing cost, low energy consumption, and low layout requirements. [15][16][17][18]
The air-cooled battery thermal management system (BTMS) is a safe and cost-effective system to control the operating temperature of battery energy storage systems (BESSs) within a desirable range. Different from the design of the air supply flow field of most BESSs in previous studies, this study proposes a novel combined the cooling air duct and the battery pack calculation method to enhance the heat dissipation of the battery. Using computational fluid dynamics (CFD) models, potential problems with numerical calculations of cooling air duct and battery packs alone and coupled simulations of the two are investigated. The important factor influencing the uniformity of air supply is identified, and creative measures for improvement are proposed. The results in this paper indicate that the uniformity of the outlet air supply does not indicate that the temperature uniformity performance of the matrix battery meets the requirements due to the variation of the sub air duct outlet pressure, and the coupling simulation of the cooling air duct and the battery pack is an essential process for BESSs. With the improvements proposed in this paper, the standard deviation coefficient of velocity is reduced from 60.3% to 12.6%. Furthermore, the innovative improvement of placing the partition at the connecting duct can regulates the battery temperature between 298.58 K and 311.73 K and ensures a maximum temperature difference of only 4.22 K for a single battery. Ultimately, the power consumption of the cooling system can be reduced by 6.9%. The results of the paper provide a guide for uniform heat dissipation in BESSs.
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