Despite tremendous progress seen in the computational fluid dynamics community for the past few decades, numerical tools are still too slow for the simulation of practical flow problems, consuming thousands or even millions of computational core-hours. To enable feasible multi-disciplinary analysis and design, the numerical techniques need to be accelerated by orders of magnitude. Reduced-order modeling has been considered one promising approach for such purposes. Recently, non-intrusive reduced-order modeling has drawn great interest in the scientific computing community due to its flexibility and efficiency and undergoes rapid development at present with different approaches emerging from various perspectives. In this paper, a brief review of non-intrusive reduced-order modeling in the context of fluid problems is performed involving three key aspects: i.e. dimension reduction of the solution space, surrogate models, and sampling strategies. Furthermore, non-intrusive reduced-order modelings regarding to some interesting topics such as unsteady flows, shock-dominating flows are also discussed. Finally, discussions on future development of non-intrusive reduced-order modeling for fluid problems are presented.
In this article, a combined experimental and analytical study has been performed to 12 investigate the transient heat generation characteristics of the lithium-ion power battery. An 13 experimental apparatus is newly built and the investigations on the charge/discharge 14 characteristics and temperature rise behavior are carried out at the ambient temperatures of 28 o C, 15 35 o C and 42 o C over the period of 1C, 2C, 3C and 4C rates. The thermal conductivity of a single 16 battery cell is measured, which is 5.22 W/(m·K). A new model of the heat generation rate based 17on the battery air cooling system is proposed by the lumped parameter approach. Comparison 18 between the simulated battery temperatures with experimental data is performed and good 19 agreement is achieved. The impacts of the ambient temperature and charge/discharge rates on the 20 heat generation rate are further analyzed. It is found that both ambient temperature and 21 charge/discharge rates have significant influences on the voltage change and temperature rise as 22 well as heat generation rate. During charge/discharge, the larger the current rate, the larger the 23 heat generation rate. The effect of the ambient temperature on the heat generation shows an 24 obvious difference with different state of charge. 25 26 Keywords: Lithium-ion battery; heat generation model; heat generation rate; temperature rise; 27 thermal management system 28 29 51 52 Subscripts 53 amb ambient 54 h convection heat transfer 55 J Joule heat 56 max maximum 57 t time 58 v volume 59 Acronyms 60 DC direct current 61 DOD depth of discharge 62 EV electric vehicle 63 HEV hybrid electric vehicle 64 ITMS integrate thermal management system 65 TMS thermal management system 66 TPS transient plane source 67 SOC state of charge 68 69 1. Introduction 70 Among the electrochemical energy storage systems, lithium-ion batteries, as a promising 71 candidate, have attracted considerable attention in many power demand applications due to their 72 advantages of large specific energy, high power density, charge/discharge cycle stability and long 73 cycle lifetime [1, 2]. With rapid development of the electric vehicles (EVs) and hybrid electric 74 vehicles (HEVs), lithium-ion batteries have been widely used in recent years [3]. However, a 75 large amount of heat will be generated because of the electrochemical reactions and physical 76 changes inside the batteries, potentially bringing out capacity fade and thermal runaway [4]. 77Therefore, it is crucial to have insight into the heat generation characteristics for maintaining 78 safety and performance of the battery.
79Many researches on the safety issues of the battery are finally ascribed to the heat generation 80 and heat dissipation at each level of the battery system [5, 6]. In order to keep the battery within 81 a reasonable temperature, an efficient thermal management system (TMS) will be needed to 82 dissipate the heat generated. Furthermore, the heat generation rate is a necessary prerequisite for 83 an efficient TMS design [7, 8]...
Abstract:A large amount of heat inside the power battery must be dissipated to maintain the 14 temperature in a safe range for the hybrid power train during high-current charging/discharging 15 processes. In this article, a combined experimental and theoretical study has been conducted to
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