Optimal air-supply mode of hybrid system with radiant cooling and dedicated outdoor air

The hybrid system with radiant cooling and dedicated outdoor air not only possesses high energy efficiency, but also creates a healthy and comfortable indoor environment. Indoor air quality will be improved by the dedicated outdoor air system(DOAS) and indoor thermal comfort can be enhanced by the radiant cooling system(RCS). The optimal air-supply mode of the hybrid system and the corresponding design approach were investigated. A full-scale experimental chamber with various air outlets and the ceiling radiant cooling panels(CRCP) was designed and established. The performances of different air-supply modes along with CRCPs were analyzed by multi-index evaluations. Preliminary investigations were also conducted on the humidity stratification and the control effect of different airflow modes to prevent condensation on CRCP. The overhead supply air is recommended as the best combination mode for the hybrid system after comprehensive comparison of the experiment results. The optimal proportion of CRCP accounting for the total cooling capacities in accord with specific cooling loads is found, which may provide valuable reference for the design and operation of the hybrid system.

Cooling System Design and Thermal Analysis of Modular Stator Hybrid Excitation Synchronous Motor

Hybrid excitation synchronous motor has the advantages of uniform and adjustable electromagnetic field, wide speed range and high power density. It has broad application prospects in new energy electric vehicles, wind power generation and other fields. This paper introduces the basic structure of hybrid excitation motor with modular stator, and analyzes the operation principle of hybrid excitation motor. The cooling structure of the water-cooled plate is designed, and the effects of the thickness of the water-cooled plate and the number of water channels in the water-cooled plate on the heat dissipation capacity of the water-cooled plate are analyzed by theoretical and computational fluid dynamics methods. The effects of different water cooling plate structures on water velocity, pressure drop, water pump power consumption and heat dissipation capacity were compared and analyzed. The influence of different inlet flow velocity on the maximum temperature rise of each part of the motor is analyzed, and the temperature of each part of the motor under the optimal water flow is analyzed. The influence of the traditional spiral water jacket cooling structure and the water-cooled plate cooling structure on the maximum temperature rise of the motor components is compared and analyzed. The results show that the water-cooled plate cooling structure is more suitable for the modular stator motor studied in this paper. Based on the water-cooled plate cooling structure, the air-water composite cooling structure is designed, and the effects of the air-water composite cooling structure and the water-cooled plate cooling structure on the maximum temperature rise of each component of the motor are compared and analyzed. The results show that the maximum temperature rise of each component of the motor is reduced under the air-water composite cooling structure.

Improved Safety for Automotive Lithium Batteries:An Innovative Approach to include an Emergency Cooling Element

This paper describes a concept for an independent and redundant safety concept for Lithium batteries in Electric and Hybrid Electric Vehicles. This concept includes an emergency cooling system based on pressurized carbon dioxide (CO2). Since carbon dioxide (CO2) is a possible medium of future mobile air conditioning (MAC) systems, the MAC system can be utilized for the one-time emergency cooling described in this paper. In the first part of the paper, some major safety aspects of automotive Li batteries are highlighted. In the second section, the paper describes a technical approach, how these batteries can be made safer. Pressurized CO2, which is a promising candidate for cooling liquids used in future mobile air conditioning (MAC) systems, is used to effectively cool down an overheating or up-heating battery in a critical state. The safety system thereby is not based on an electrical effect, but on a direct and fast-reacting thermal conduction, avoiding a thermal runaway of individual cells. The application of the proposed system is to act preventively just before the thermal runaway gets uncontrollable. In this case, the limited amount of CO2, which is available in the MAC system, fulfils the emergency cooling requirements. The combination of standard car components for the concept leads to an only moderate increase of the total weight and the additional system costs. Therefore, the described system might be of interest for car, battery and air conditioning system producers. This paper explains that the synergetic combination of CO2-based MAC systems and Li-based batteries is an innovative approach to improve environmental compatibility in future vehicles. The concept is proven experimentally on a lab scale with battery cells and battery packs consisting of four serially connected cells, respectively.

Waste heat water pumping model with direct contact cooling

The performance of a patented water pumping model with steam-air power was presented, which operates automatically by direct contact cooling method. The main objective was to study feasibility of a pumping model for underground water. In this model, a heater installed within the heat tank represented sources of waste heat as energy input for finding appropriate conditions of the 10 L pump model. The system operation had five stages: heating, pumping, vapor flow, cooling, and water suction. The overall water heads of 3, 4.5, 6 and 7.5 m were tested. At the same time, it was found that the pump with 50% air volume is sufficient for pumping water to a desired level. In the experiment, the temperatures in the heating and pumping stages were 100-103 °C and 80-90 °C, respectively. The pressure in the pumping stage was 12-18 kPa, and the pressure in the suction stage was about-80 kPa, sufficient for the best performance. It could pump 170 L of water at a 2 m suction head, 120 L at a 3.5 m suction head, 100 L at a 5 m suction head, and 65 L at a 6.5 m suction head in 2 h. A mathematical model for larger pumps was also presented, which operates nearly the same as the present system. Economic analysis of the 10 L pump was also included.

混动汽车整车热管理系统冷却优化

为了使整车能量控制与利用更加具有合理性与有效性,从而提高整车的性能,以某混动汽车为研究对象,基于某仿真软件搭建空调系统模型和电池电机冷却系统模型,进而拟合成协调配合的热管理系统模型。通过对热管理系统模型结构优化,使得电池组可由风冷和液冷两种方式共同冷却。提出将空调系统与电池组冷却系统进行热量传递和转换的控制方案,并在NEDC工况下对比空调座舱独立热管理系统冷却方案和空调座舱与电池组协同热管理系统冷却方案的差异。研究结果表明,在保证座舱舒适性的前提下,采用空调座舱与电池组协同热管理系统的冷却方案更加节能,有助于整车剩余电量与行驶里程的提高。

液冷服务器中多连接器拓扑的信号完整性研究

对3个高速连接器的拓扑和4个高速连接器的拓扑分别在液冷环境和风冷环境中的信号质量进行仿真。在液冷环境中,对4个高速连接器的拓扑中高速连接器间间距进行仿真。仿真结果表明:风冷环境下PCIe 5.0 Tx链路的信号质量优于液冷环境下PCIe 5.0 Tx链路的信号质量;高速连接器个数对液冷环境下PCIe 5.0 Tx链路的信号质量影响较风冷环境下更大;优化后的高速连接器间间距可以改善液冷环境下PCIe 5.0 Tx链路的信号质量。

电池热管理对城市客车能耗的影响

先介绍了电池热管理技术(即电池冷却系统)的重要性,并以电池液冷系统作为研究对象,以国内某地区在营运的城市客车的数据为例,结合电池液冷系统的零部件结构和工作原理,分析了电池液冷系统对纯电动客车能耗的影响,以及由于能耗的增加对单车运营成本的影响。

混合动力机车电池组液冷板流道结构选型研究

为了选出混合动力机车电池组液冷板的最优流道结构,文章结合电池组液冷原理提出了4种流道结构模型,并在环境温度35℃、冷却液进口速度2 L/min和进口温度25℃的条件下,进行热仿真分析。通过对比分析发现,随着并行流道数量的增加,电池组的平均温度、最高温度、最大温差均呈上升趋势,冷却液的进出口压差均呈下降趋势。综合评价指标及冷却液流速情况,两并行流道被确定为该电池组最适配的液冷板流道结构。

堆叠式车载超级电容器热管理方式分析

本研究使用COMSOL Multiphysics 6.0软件对堆叠式车载超级电容器建立了有限元模型,并且针对空冷和液冷两种不同的热管理方式分别建立了热模型以对比其热管理效果。首先,在相同的参数变化范围内,分别研究了空冷和液冷两种方式的超级电容器的最高温度与换热介质的初始温度、在入口处的流速以及超级电容器模组的发热功率之间的关系。结果表明,换热介质的初始温度越高,超级电容器的发热功率越大,则超级电容器的最高温度越高,而换热介质在入口处的平均流速越大,则超级电容器的最高温度越低,且存在一个临界流速1.5m/s,超过该临界值之后,二者的相关性将大大减弱。此外,基于参数化研究结果,设定相同的操作参数,深入分析了这两种热管理方式的换热过程,解释了本研究中空冷和液冷在高度方向上温度梯度方向相反的现象,并从最高温度与温差、温度分布和换热时间三个方面对比了二者的热管理效果。结果表明,液冷超级电容器的最高温度更低,温差很小,温度分布十分均匀,且换热时间远少于空冷超级电容器,热管理效果更好。

电化学储能系统热管理技术研究进展

锂电池储能具有循环特性好、响应速度快、系统综合效率高等特点,是目前市场上推广应用最多的储能方式。从电化学储能系统热管理关键技术出发,对空气冷却和液体冷却(冷却板液体冷却及浸没式液体冷却)的电化学储能热管理技术的研究现状进行了介绍,并对浸没式液冷技术的发展进行了展望。随着电化学储能迅速发展,浸没式液冷热管理技术将会大规模应用,与之配套的浸没式冷却液未来的潜在市场容量可达万吨级以上。(图3表0参考文献9)

MMC水冷系统故障分析与参数设计

水冷系统是模块化多电平换流器(Modular Multilevel Converter,MMC)必不可少的辅助系统,其正常运行是换流阀可靠工作的保证。这里以南京220 kV模块化多电平统一潮流控制器(Modular Multilevel Unified Power Flow Controller,MMUPFC)为研究对象,对MMUPFC及换流阀水冷系统进行了结构介绍。其次,针对目前MMUPFC正常运行时水冷系统去离子支路出现漏气的问题,在ANSYS-FLUENT仿真软件中对MMUPFC水冷系统去离子罐内液-气进行了多相流仿真建模,对故障形成机理进行了理论分析和研究。通过仿真研究,对水冷系统去离子罐内液位参数进行了设计。最后,在南京220kV MMUPFC换流站对水冷系统参数设计进行了实验验证,实验结果验证了这里设计的正确性和合理性。

液体硅酸钠用冷却输送装置的优化改进

液体硅酸钠因黏度高、易结晶,给其冷却输送带来了较大困难。介绍了一种新型液体冷却输送装置的结构、工作原理及技术特点。液体硅酸钠冷却输送应用效果证明,该新型装置在不改变流量的基础上提升冷却系统的运行效率,保证了高黏度液体冷却输送的高效和节能。

混合动力汽车高速工况下制冷性能影响分析

参考《QCT 658-2000汽车空调整车降温性能试验方法》国家法规评价标准,运用KULI软件搭建了混合动力汽车的空调系统冷媒回路仿真模型及电池包冷却回路仿真模型。通过仿真试验曲线,混合动力汽车运行车速为100km/h高速稳态工况下,在压缩机转速2000~7000rpm区间,随着转速升高,吹面出风温度逐渐降低,而主驾头部温度降温不明显;压缩机优先推荐转速6000rpm,7000rpm作为第二选择。

Electrically driven chip cooling device using hybrid coolants of liquid metal and aqueous solution

Heat dissipation of electronic devices keeps as a tough issue for decades. As the most classical coolant in a convective heat transfer process, water has been widely adopted which however inherits with limited thermal conductivity and relies heavily on mechanical pump. As an alternative, the room temperature liquid metal was increasingly emerging as an important coolant to realize much stronger enhanced heat transfer. However, its thermal capacity is somewhat lower than that of water, which may restrict the overall cooling performance. In addition, the high cost by taking too much amount of liquid metal into the device also turns out to be a big concern for practical purpose. Here, through combining the individual merits from both the liquid metal with high conductivity and water with large heat capacity, we proposed and demonstrated a new conceptual cooling device that integrated hybrid coolants, radiator and annular channel together for chip thermal management. Particularly, the electrically induced actuation effect of liquid metal was introduced as the only flow driving strategy, which significantly simplified the whole system design. This enables the liquid metal sphere and its surrounding aqueous solution to be quickly accelerated to a large speed under only a very low electric voltage. Further experiments demonstrated that the cooling device could effectively maintain the temperature of a hotpot(3.15 W/cm^2) below 55oC with an extremely small power consumption rate(0.8 W). Several situations to simulate the practical working of the device were experimentally explored and a theoretical thermal resistance model was established to evaluate its heat transfer performance. The present work suggests an important way to make highly compact chip cooling device, which can be flexibly extended into a wide variety of engineering areas.

Liquid Air Energy Storage for Decentralized Micro Energy Networks with Combined Cooling,Heating,Hot Water and Power Supply

Liquid air energy storage(LAES)has been regarded as a large-scale electrical storage technology.In this paper,we first investigate the performance of the current LAES(termed as a baseline LAES)over a far wider range of charging pressure(1 to 21 MPa).Our analyses show that the baseline LAES could achieve an electrical round trip efficiency(e RTE)above 60%at a high charging pressure of 19 MPa.The baseline LAES,however,produces a large amount of excess heat particularly at low charging pressures with the maximum occurred at~1 MPa.Hence,the performance of the baseline LAES,especially at low charging pressures,is underestimated by only considering electrical energy in all the previous research.The performance of the baseline LAES with excess heat is then evaluated which gives a high e RTE even at lower charging pressures;the local maximum of 62%is achieved at~4 MPa.As a result of the above,a hybrid LAES system is proposed to provide cooling,heating,hot water and power.To evaluate the performance of the hybrid LAES system,three performance indicators are considered:nominal-electrical round trip efficiency(ne RTE),primary energy savings and avoided carbon dioxide emissions.Our results show that the hybrid LAES can achieve a high ne RTE between 52%and 76%,with the maximum at~5 MPa.For a given size of hybrid LAES(1 MW×8 h),the primary energy savings and avoided carbon dioxide emissions are up to 12.1 MWh and 2.3 ton,respectively.These new findings suggest,for the first time,that small-scale LAES systems could be best operated at lower charging pressures and the technologies have a great potential for applications in local decentralized micro energy networks.

电动汽车驱动电机冷却技术研究发展综述

电动汽车驱动电机作为电动汽车的核心部件,其温升问题直接影响着电动汽车的稳定性以及安全性,因此选择合适的热分析模型和冷却结构在电动汽车驱动电机的设计过程中有着非常重要的现实意义。针对电动汽车驱动电机冷却问题,以电动汽车驱动电机“热的来源-热的处理-实际应用”为主线,对近年来国内外电动汽车驱动电机的冷却设计发展现状进行了综述。对电动汽车驱动电机热源计算方法以及各类型损耗基本原理进行了简述。按照自然冷却、强迫风冷、液冷的分类方式阐述了不同种类电动汽车驱动电机冷却系统的国内外应用现状,并总结了近年来电动汽车驱动电机冷却结构的实际应用情况及其优缺点。这些工作为电动汽车驱动电机的研发提供了一定的参考。

Hybrid Chiller Plant Optimization Strategies for Hotel Building on Nile River of Egypt

Hybrid chiller plants (HCPs) using multiple chillers and different energy sources are highly recommended in several energy applications in non-residential buildings such as hospitals and hotels. Time of use and cooling load profiles are significant factors that should be carefully considered either in chiller plant design or in chiller sequencing operation. This article aims to present an operation planning of HCP which consists of both electric and non-electric chillers. Four operational strategies are proposed and solved to compare their coefficients of performance and economics of running costs. A typical hotel building located on the Nile river in Egypt is selected to perform the current thermal and economic case study. The total cooling load profile of this hotel building is 4000 refrigeration tonnage (TR), which is simulated to optimize chiller sequence of operation and to select optimal design conditions of both numbers for electric and non-electric chillers used in HCP. The results of this comparative study for running cost are defined using various design configurations with different several chiller sequences available for each configuration. Then, the results of COPs, and operational running cost and initial cost are presented in this article also. The comparison aims to find the optimal design and operational sequencing for HCPs on thermal basis and economic analysis which were attached in this article. Recommendations and suggestions for future work are attached at the end of this article.

车用锂离子动力电池风冷散热系统研究进展

锂离子电池作为电动汽车动力电池首选,维持其工作在最佳温度范围需要应用散热系统。针对常用的风冷散热系统,阐述了不同类型的特点,综述了国内外在电池内部流道、进出风口结构、冷却空气流体参数等方面开展的仿真与实验研究,以及采用优化算法和优化策略,改善电池内部温度和温差的优化设计研究。为克服风冷散热系统冷却效率低及密封性不足的问题,基于风冷散热系统的混合冷却系统被研究者广泛提出。

基于Icepak的船舶储能电池散热特性仿真分析

目前全电船舶储能系统主要由锂电池构成,对其进行合理的热设计是保证储能系统安全可靠运行的关键。以某型船用储能电池包为研究对象,分别设计其风冷和水冷散热系统,基于Icepak软件进行两类冷却系统的散热特性仿真及评估。通过改变风冷散热系统的入口风速、风扇半径、风扇数量,以及液冷散热系统的冷却液流速、冷却液入口温度等参数,对比分析参数变化对系统散热效果的影响,为全电船舶储能系统散热方案的选取和散热系统的设计提供依据。

锂离子电池热管理技术

电动汽车在应对气候变化和减少碳排放方面显示出了巨大潜力,电池作为电动汽车的动力来源,在性能和安全方面受温度影响很大。一套有效的热管理控制系统能使电池组温度保持在最佳工作范围内,提高整车的续驶里程。主要总结了目前对电池进行散热和保温的主流电池热管理技术——风冷、液冷、相变冷却、热管冷却以及电池加热技术。提出电池热管理技术应往智能化、集成化、与机器学习相结合、能够自适应调节电池生态温度的方向发展,将会有很大的研究空间。