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中国科学:技术科学（英文版）
中国科学:技术科学（英文版）

周光召

月刊

1674-7321

sales@scichina.org

010-64019820

100717

北京东黄城根北街16号

中国科学:技术科学（英文版）/Journal Science China Technological SciencesCSCDCSTPCDEISCI
查看更多>>《中国科学》是中国科学院主办、中国科学杂志社出版的自然科学专业性学术刊物。《中国科学》任务是反映中国自然科学各学科中的最新科研成果，以促进国内外的学术交流。《中国科学》以论文形式报道中国基础研究和应用研究方面具有创造性的、高水平的和有重要意义的科研成果。在国际学术界，《中国科学》作为代表中国最高水平的学术刊物也受到高度重视。国际上最具有权威的检索刊物SCI，多年来一直收录《中国科学》的论文。1999年《中国科学》夺得国家期刊奖的第一名。
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    Preface

    CAO Feng
    3631页
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    Exploration and numerical study of new structures for high-efficiency and low-resistance vehicle-mounted plate-fin heat exchanger based on the three-field synergy principle

    JIANG TaoLI MingJiaYANG JiaQiCAO YuanFu...
    3632-3646页
    查看更多>>摘要：As the power density of the power transmission device increases,heat exchangers are required to dissipate more heat and provide better flow resistance in the limited space of the vehicle.In this study,the synergy mechanism of the temperature field,pressure field,and velocity field in the serrated fin channel of the plate-fin heat exchanger(PFHX)was thoroughly analyzed under the guidance of the three-field synergy principle.This study also quantitatively revealed the distribution of the angle θ between the temperature gradient and velocity,and the angle α between the pressure gradient and velocity.For the regions in the channel where θ was too large(i.e.,poor synergy between temperature and velocity fields)and α was too small(i.e.,poor synergy between pressure and velocity fields),high-efficiency and low-resistance fin structures were proposed.The performance im-provement of the new structures was quantified using the comprehensive heat transfer and flow resistance performance eva-luation plot in the three-field synergy standard.The results indicate that the new structures improve the synergy of the three fields in the channel.When the air velocity is 15 m s-1,the average synergy angle θm between the temperature gradient and the velocity of the two structures,changing the inlet flow direction and the slotted fin,decreases from 83.4°to 80.3°and 82.8°,respectively.The outlet temperature increases by 2.3 and 1.6 K,respectively,compared to the basic structure,indicating enhanced the heat transfer of the PFHX.By changing the shape of the fin cross-section,the average synergy angle αm between the pressure gradient and the velocity increased from 143.6°to 150.8°,while θm increased by only 0.6°.The pressure loss was reduced by 15.2％compared to the basic structure,resulting in a significant decrease in pressure drop while maintaining essentially the same heat transfer performance.Meanwhile,the optimized PFHX can increase the heat transfer rate by 0.2％-8％under identical pump power.This work provides guidance on selecting high-efficiency and low-resistance vehicle-mounted PFHXs.
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    Experimental determination of heat generation rates of lithium-ion batteries by thermal protection method

    SHI JingHeZHANG HengYunYU HongWANG XiaoLin...
    3647-3658页
    查看更多>>摘要：Experimental determination of heat generation rates is crucial in the thermal safety design of automotive batteries.A thermal protection method(TPM)is proposed to determine the heat generation rates of 18650 cylindrical lithium-ion batteries under different discharge rates.The physical model based on the thermal protection method is established,and its feasibility is demonstrated through theoretical analysis.In the experimental setup,by introducing lateral thermal protection batteries(TPB)to minimize the heat loss of the center test battery(CTB),heat generation rates of the battery can be obtained based on the temperature change of the CTB.The average heat generation rates of the battery at 1,2,and 3 C discharge rates are found to be 0.255,0.844,and 1.811 W,respectively,which can be quadratically correlated with the discharge rate.In addition,a benchmark test of the present measurement against the commonly used accelerating rate calorimeter(ARC)was conducted.Relatively small deviations of 3.77％,4.20％,and 1.09％were identified in the heat generation rates for the discharge rates at 1,2,and 3 C.In comparison with the ARC equipment,the present TPM can be more representative of the transient battery heat generation characteristics with a much shorter time for thermal equalization.Finally,to further verify the accuracy of the present method,standard samples of the same size as the actual battery were made,which were capable of controlling heat generation through a direct current power supply.A comparison of the heat inputs of the standard sample with the heat generation rates measured by the thermal protection method shows a relative deviation of 1.01％maximum.With high measurement accuracy and an easy-to-build experimental setup,the proposed method has promising prospects in automotive applications.
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    Design and dynamic analysis of a novel scroll compressor-expander unit for the CO2 air conditioning system in electric vehicles

    HU HaoYuYANG XuCAO FengYIN Xiang...
    3659-3672页
    查看更多>>摘要：Transcritical CO2 refrigeration cycle systems hold significant promise for improving the energy efficiency of air conditioning system in vehicles,diminishing reliance on traditional energy sources,and reducing environmental impact.Utilizing a scroll compressor-expander unit(SCEU)to recover energy during the expansion process enables the effective conversion of expansion work into useful work,thereby enhancing the efficiency of the entire refrigeration cycle.This paper provides a detailed description of the geometric structure of the SCEU,and based on this,conducts an exhaustive mechanical analysis of its orbiting scrolls and main shaft,thus establishing dynamic models.Computational results indicate that in transcritical CO2 refrigeration systems,the SCEU aids in recovering expansion work,increasing the coefficient of performance(COP)by 8.2％under standard operating condition.Additionally,this paper pioneers in studying the dynamic characteristics of SCEU under variable conditions.It is found that although the COP of the systems decreases with the rise of working pressure,compared to traditional systems,its rate of improvement progressively increases.Under conditions of negligible leakage and an isentropic efficiency of 60％,the SCEU can potentially increase the COP of the system by up to 9.8％.
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    Performance analysis of an R290 vapor-injection heat pump system for electric vehicles in cold regions

    YANG YunChunSHAO WenCongYANG TianYangZOU HuiMing...
    3673-3681页
    查看更多>>摘要：High-performance automotive thermal management systems with environment-friendly refrigerants are essential for achieving carbon peaking and carbon neutrality goals.In this study,an R290 vapor-injection heat pump system for electric vehicles is developed and experimentally investigated.The effects of refrigerant charge mass,injection pressure,and in-cabin air tem-perature are analyzed in ambient temperatures from-30℃ to 0℃.The results show that the vapor-injection system can increase the coefficient of performance(COP)and heating capacity by 14.3％and 15.9％at 0℃/20℃(ambient/in-cabin temperature)compared with the basic system,and this increase becomes more significant at-20℃/20℃ with improvements of 32.5％and 38.1％,respectively.At a lower ambient temperature of-20℃,increasing refrigerant charge mass contributes to a more pronounced increase in heating capacity than at 0℃,which results from the more significant increase in injection mass flow.The optimal COP at various injection pressures are 2.07 and 1.63 at 0℃ and-20℃ ambient temperatures,corresponding to the relative injection pressures of 0.60 and 0.57,and the injection flow ratios of 0.23 and 0.29,respectively.At-30℃/0℃,a COP of 1.69 can be achieved.
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    Prior-based patch-level representation learning for electric vehicle battery state-of-charge estimation across a wide temperature scope

    YE SongTaoAN Dou
    3682-3694页
    查看更多>>摘要：Electric vehicles(EVs)powered by lithium-ion batteries have emerged as a global development trend.To ensure the safe and stable driving of EVs,it is imperative to address battery safety and thermal management issues,which rely heavily on the precise state-of-charge(SOC)estimation of the battery.However,estimating SOC under uncontrolled environmental temperatures remains an unresolved challenge.This study proposes a patch-level representation learning model based on domain knowledge to estimate the SOC over a wide temperature range.First,patches were adopted as inputs instead of traditional points,thereby mitigating error accumulation and capturing dynamic changes in the battery from these more informative representations.Second,the open-circuit voltage(OCV)-SOC-temperature relationship was incorporated to obtain the temperature-related SOC priors.Subsequently,the prior was updated recursively along the time dimension to obtain a more precise SOC estimate.The accuracy of the proposed model was confirmed experimentally for three driving cycles at six ambient temperatures,significantly reducing the root mean square error by 48.19％compared to popular existing models.Notably,the performance of the proposed method had an excellent improvement of 51.52％and 57.20％at-10℃ and-20℃,respectively.Moreover,the parameter size of the proposed method was 39.748 KB,which significantly promoted the deployment and application of data-driven models in the real world.
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    Analysis and optimization of thermal management system for cylindrical power battery based on distributed liquid cooling plates

    ZHAO YangZHANG TaoWANG ChunTANG YinBo...
    3695-3706页
    查看更多>>摘要：To ensure the battery works in a suitable temperature range,a new design for distributed liquid cooling plate is proposed,and a battery thermal management system(BTMS)for cylindrical power battery pack based on the proposed cooling plate is also investigated.To verify the accuracy of the battery model and battery pack numerical calculation model used for simulation,an experiment is conducted for the liquid cooling BTMS.The influence of key working parameters,including the cooling water inlet flow,ambient temperature and working conditions,are investigated.The results show that at the discharge rate of 3 C,the best cooling performance can be achieved when the total inlet mass flow rate is 3.2 g/s and the flow distribution is 3:1:1:3.The obtained maximum temperature is 29.6℃ and the maximum temperature difference is 2.1℃.When the ambient temperature is in the range of 20℃ to 50℃,the proposed BTMS can keep the temperature of battery pack in the proper range.Finally,different inlet flow rates are recommended according to different battery working states.
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    Thermodynamic analysis of auto-thermal chemical looping hydrogen production systems

    LI PeiJingLIU TaiXiuLI JiChaoQIN YuanLong...
    3707-3723页
    查看更多>>摘要：Chemical looping hydrogen production is of interest because of its ability to simultaneously produce hydrogen and capture CO2 at the same time.Achieving an energy balance is crucial in chemical-looping hydrogen production systems.Decreasing the external heat duty can effectively reduce carbon capture and energy conversion efficiency.In this study,two auto-thermal chemical looping H2 generation systems are proposed.An adiabatic counter current moving bed chemical looping H2 generation system using CH4 as fuel and Fe2O3 and Al203(inert carriers)as oxygen carriers(OC)is proposed to analyse the energy balance and exergy balance of the systems.A parametric analysis was conducted to investigate the influence of the reaction ratio and temperature on the product outcomes,leading to the determination of optimal operating conditions.Subsequently,the impact of hydrogen production efficiency and reduction reactor outlet stream ratio and inert component proportion in the oxygen carrier on the system's thermal balance was analysed under these optimal conditions,culminating in the identification of key parameters for the two auto-thermal systems.Energy balance and exergy balance analyses were employed to compare the energy efficiency and irreversible losses of the autothermal and reference systems.The results demonstrated that the autothermal system enhanced the energy efficiency by 2.5％and the CO2 capture rate by 11％(percentage points)compared with the reference system.
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    Numerical study on flow and heat transfer characteristics of S-CO2 in a novel parabolic trough collector tube utilizing impinging jets under non-uniform heat flux boundary

    HE ZhengLI QingZHANG YaRuZHOU Ping...
    3724-3740页
    查看更多>>摘要：Parabolic trough collectors are essential components of solar thermal power plants,and the non-uniform heat flux on the walls may lead to low heat transfer coefficients and large wall temperature differences.A novel jet structure is proposed in this paper to explore the feasibility of adopting impinging jets to improve the heat transfer performance of the collector tube with supercritical carbon dioxide(S-CO2)as the working fluid.The physical model is built based on several assumptions,and numerical simulations are performed under the mass flow rate of 0.25-0.75 kg/s and the average surface heat flux of 14.7-33 kW/m2.Firstly,performance comparisons are made between the jet and tube-in-tube structures.The results show that the average heat transfer coefficient h of the jet structure is 46.5％higher than that of the tube-in-tube structure and the corresponding average temperature difference ΔT between the wall and S-CO2 is 31.7％lower.Secondly,the effects of the jet hole circumferential position and diameter on heat transfer are investigated.It's found that by adjusting the circumferential position of the jet hole from 60°to 120°and matching the impingement area of the jets and the high heat flux region,h can be increased by 14.2％and ΔT can be reduced by 12.4％.h is also found to be increased by 77.4％when the jet hole diameter is reduced from D=9.7 mm to D=5 mm.Furthermore,the jet structure is further modified by incorporating it with the eccentric configuration.The effect of eccentricity e is studied in detail,and results show that appropriate eccentricity results in higher h and smaller ΔT due to the decreased impingement distance and the increased heat transfer.This study can guide the design and optimization of parabolic trough collectors.
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    Experimental evaluation of a 10-kW parabolic trough solar reactor prototype driving Ni-based chemical looping redox cycle with methane for solar fuel production

    JIANG QiongQiongCAO YaLiSUN FanXING XueLi...
    3741-3754页
    查看更多>>摘要：Solar fuels can be cost-effectively produced using solar-driven thermochemical processes.Hybridizing thermochemical pro-cesses can not only effectively utilize solar energy but also achieve clean conversion of fossil fuels.With this method,the solar energy level can be upgraded,and the irradiation fluctuation can be solved.It is worth noting that solar reactors play an important role in this technology.In this study,we demonstrated a 10-kW parabolic trough solar-driven reactor prototype for methane reforming and solar fuel production.The primary setup of the experimental platform consisted of a trough concentrating solar collector,chemical looping reforming reactors with indirect heat transfer,and associated auxiliary equipment.Experiments on the chemical looping redox cycle were conducted using nickel-based NiO/NiAl2O4 as the OC under different direct normal irradiation(DNI)from 740 to 920 W/m2.Under irradiation at approximately 920 W/m2,the methane conversion initially increased to 92％before declining to 75％from 0 to 900 s and then to 2500 s.Under these conditions,the syngas concentration increased from 30％to 57％and the solar-to-fuel efficiency reached 59％.The oxygen transfer rate during the chemical looping redox cycle was also experimentally investigated.Cyclic redox cycle experiments were conducted for 540 min of long-term operation to assess the duration and adaptability performance.The fractional oxidation can consistently return to almost 1.0 after each redox cycle,indicating strong reactivity and regenerability when exposed to different levels of DNI.The reactivity of the chemical looping redox cycle during typical autumn and winter days was also investigated and discussed.This study aimed to prove that this 10-kW parabolic trough reactor prototype can harness 500℃ solar heat to drive efficient methane reforming,offering a promising avenue for solar fuel production.
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