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译文题目：Automotive Radiator Performance 汽车散热器性能 Automotive Radiator Performance Abstract Automotive engine cooling system takes care of excess heat produced during engine operation. It regulates engine surface temperature for engine optimum efficiency. Recent advancement in engine for power forced engine cooling system to develop new strategies to improve its performance efficiency. Also to reduce fuel consumption along with controlling engine emission to mitigate environmental pollution norms. This paper throws light on parameters which influence radiator performance along with reviews some of the conventional and modern approaches to enhance radiator performance. Index TermsAutomotive engine cooling system, Performance, RadiatorI. INTRODUCTION Automotive engine cooling system takes care of excess heat produced during engine operation. It regulates engine surface temperature for engine optimum efficiency. Most automotive engine cooling systems consist of the radiator, water pump, cooling fan, pressure cap and thermostat. Radiator is the prime component of the system.Radiator is a heat exchanger that removes heat from engine coolant passing through it. Heat is transferred from hot coolant to outside air. Radiator assembly consists of three main parts core, inlet tank and outlet tank. Core has two sets of passage, a set of tubes and a set of fins. Coolant flows through tubes and air flows between fins. The hot coolant sends heat through tubes to fins. Outside air passing between fins pickups and carries away heat.Manuscript received February, 2013. Pawan S. Amrutkar, Department of Mechanical Engineering, Sinhgad Academy of Engineering, University of Pune, India. Sangram R. Patil, Department of Mechanical Engineering, Sinhgad Academy of Engineering, University of Pune, India.Performance of engine cooling system is influenced by factors like air and coolant mass flow rate, air inlet temperature, coolant fluid, fin type, fin pitch, tube type and tube pitch etc. While designing cooling system three worst conditions considered based on above parameters. High altitude : At high altitude, air density becomes low and hence affects air mass flow rate. Summer conditions : During summer surrounding air is hot i.e. air inlet temperature is more. Maximum power : Engine condition producing maximum power like when vehicle is climbing uphill, maximum heat rejection is required during this condition. To compensate all these factors radiator core size required may be large.II. LITERATURE REVIEW C. Oliet, A. Oliva, J. Castro, C.D. studied different factors which influence radiator performance. It includes air and coolant flow, fin density and air inlet temperature. It is observed that heat transfer and performance of radiator strongly affected by air and coolant mass flow rate. As air and coolant flow increases cooling capacity also increases. When air inlet temperature increases, heat transfer and thus cooling capacity decreases. Smaller fin spacing and higher louver fin angle have higher heat transfer. Fin density can be increased till it blocks the air flow and heat transfer rate decreases. JP Yadav and Bharat Raj Singh in their studies also presented parametric study on automotive radiator. In the performance evaluation, a radiator is installed into a test setup. The various parameters including mass flow rate of coolant, inlet coolant temperature; etc. are varied. Following remarks are observed during study : Influence of coolant mass flow cooling capacity of the radiator has direct relation with the coolant flow rate. With an increase in the value of cooling flow rate, there is corresponding increase in the value of the effectiveness and cooling capacity. Influence of coolant inlet temperature with the increase in the inlet temperature of the coolant the cooling capacity of the radiator increases. Mazen Al-Amayreh in his study, tested the thermal conductivities of ethylene glycol + water, diethylene glycol + water and triethylene glycol + water mixtures, measured attemperatures ranging from 25C to 40C and concentrations ranging from 25 wt. % glycol to 75 wt.% glycol. Increasing the concentration of glycol leads to decrease of thermal conductivity. Increasing the temperature of mixture resulted in slight increase in thermal conductivity. The various techniques are used to enhance the performance of automotive engine cooling system. It may be either conventional or modern approach. Conventional approach relies on fin, tube and fan design optimization. Modern techniques are based on new technologies like nano-technology, heat load averaging capacity or actuator based engine cooling system. This paper reviews some of the conventional and modern approaches focusing on radiator performance enhancement.P. K. Trivedi, N. B. Vasava illustrated the effect of Tube pitch for best configured radiator for optimum performance. Heat transfer increases as the surface area of the radiator assembly is increased. This leads to change the geometry by modifying the arrangement of tubes in automobile radiator to increase the surface area for better heat transfer. The modification in arrangement of tubes in radiator is carried out by studying the effect of pitch of tube by CFD analysis using CFX. Results Shows that as the pitch of tube is either decreased or increased than optimum pitch of tubes, the heat transfer rate decreases.Pitambar Gadhve and Shambhu Kumar described use of dimple surface to improve forced convection heat transfer. Heat transfer enhancement is based on principle of scrubbing action of cooling fluid inside the dimple. Surface dimples promote turbulent mixing in flow and enhance heat transfer. An experimental set up has been designed and fabricated to study effect of dimpled surface on heat transfer in rectangular duct. Results compared with flat surface tube and found heat transfer enhancement over the later one. P. Gunnasegaran, N. H. Shuaib, and M. F. Abdul Jalal in their study numerical simulations on fluid flow and heat transfer characteristics over louver angle fin Compact Heat Exchangers are reported. A computational domain from the fluid inlet to outlet is solved. The impacts of using variable louver angles (+2, +4, 2, 4, and uniform angle 20) and louvered fin with variable fin pitches (1 mm, 2 mm, and 4mm) on both thermal and hydraulic of CHE are presented. The Nusselt number is higher for increased or decreased louver angle compared to uniform louver angle. The variable louver angle patterns and louver fin with smaller pitch applied in CHEs could effectively enhance the heat transfer performance with moderate degradation of pressure drop penalty compared to plain fin surface of CHE. Prof. D. K. Chavan, Prof. Dr. G. S. Tasgaonkar explained conventional radiator size is rectangular which is difficult for circular fan to cover whole surface area. It creates lower velocity zones at corners giving less heat transfer. Author has proposed to eliminate corners and develop circular shape radiator which is compact, more efficient and leads to minimum power consumption to drive a fan and maximum utilization of air flow.Considering limitations of conventional techniques to improve cooling system performance various new technologies are adopted. Research is going on to stabilize the results.K.Y. Leong, R. Saidur, S.N. Kazi, A.H. Mamun described use of nanofluid based coolant in engine cooling system and its effect on cooling capacity. It is found thatnano-fluid having higher thermal conductivity than base coolant like 50%/50% water and ethylene glycol. It increases heat transfer. So for same heat transfer, radiator core area can be reduced compared to base one. It finds better solution to minimize area. Thermal performance of a radiator using nanofluid is increased with increase in pumping power required compared to same radiator using ethylene glycol as coolant. John Vetrovec carried work on engine cooling system with heat load averaging capacity using passive heat load accumulator. Heat load accumulator is phase change material which stores heat generated during peak and dissipates stored heat during reduced heat load condition. This is achieved by sacrificing phase change of PCM from solid to liquid or vice versa. This leads to compact heat exchanger for same heat rejection. Also it reduces load on cooling system. System can handle high transient loads and permits faster warm up during cold engine start. M.H. Salah, P.M. Frick, J.R. Wagner, D.M. Dawson discussed about hydraulic actuated cooling system. Actuators can improve temperature tracking and reduce parasitic losses. Actuator based engine cooling system uses controller to control coolant pump and radiator fan operating conditions. It provides power to system component as per requirement. Thus it regulates power consumption of system component with cooling capacity. A nonlinear back stepping robust controller is used to regulate engine coolant temperature in hydraulic based thermal management system. Proposed controller maintained the coolant temperature to its set point with system improvement. Use of this system offers greater power density with compact in nature. III. FUTURE SCOPE Engine cooling system can contribute in some of the engine aspects like reduction in fuel consumption thus minimizing exhaust and fuel emission. This can be achieved by keeping engine at optimum thermal operating conditions. Also thermal load on engine, engine components, lubricating fluid can be reduced. Effective engine cooling system can help to shorten engine warm up period during cold start and heat loss recovery to improve driving comfort. Reduction in weight and required space to fit system on a vehicle is the most challenging task in developing cooling system. Also efforts to be taken to implement use of emerging technologies like nano-technology and to stabilize the results of these systems. In short, future challenges include developing more compact, light weight, improved performance and economical engine cooling system.IV. PROPOSED WORK The proposed work is concerned with developing excel sheet to calculate heat rejection. Few input parameters will give exact idea regarding heat rejection. Sheet will help to estimate effect of varying tube and fin density, coolant flow rate etc. on heat rejection. Theoretical calculation of radiator core size and heat rejection for a given engine inputs. Validation of core size by simulation software and comparing theoretical heat rejection with simulation results. Optimizing core size as per heat rejection requirement. 3D modeling of radiator components header, tubes, fins and tanks. Finite element analysis of radiator to test its robustness for thermal and pressure loads. Prototype development to validate the radiator performance.1 C. Oliet, A. Oliva, J. Castro, C.D. Perez-Segarra, Parametric studies on automotive radiators, Applied Thermal Engineering, 27, 2007 2 JP Yadav and Bharat Raj Singh, Study on Performance Evaluation of Automotive Radiator, S-JPSET : ISSN : 2229-7111, Vol. 2, Issue 2, 2011 3 Mazen Al-Amayreh, Experimental Study of Thermal Conductivity of Ethylene Glycol Water Mixtures, European Journal of Scientific Research, ISSN 1450-216X Vol.44 No.2, 2011 4 P. K. Trivedi, N. B. Vasava, Effect of Variation in Pitch of Tube on Heat Transfer Rate in Automobile Radiator by CFD Analysis, International Journal of Engineering and Advanced Technology (IJEAT) ISSN: 2249 8958, Volume-1, Issue-6, 2012 5 Pitambar Gadhave, Shambhu Kumar, Enhancement of forced Convection Heat Transfer over Dimple Surface Review, International Multidisciplinary e Journal, 2012 6 P. Gunnasegaran, N. H. Shuaib, and M. F. Abdul Jalal. The Effect of Geometrical Parameters on Heat Transfer Characteristics of Compact Heat Exchanger with Louvered Fins, ISRN Thermodynamics, Volume 2012 7 Prof. D. K. Chavan, Prof. Dr. G. S. Tasgaonkar, Thermal Optimization of Fan assisted Heat Exchanger (Radiator) by Design Improvements, International Journal of Modern Engineering Research (IJMER), Vol.1, Issue 1, 2011 8 K.Y. Leong, R. Saidur, S.N. Kazi, A.H. Mamun, Performance investigation of an automotive car radiator operated with nanofluidbased coolants (nanofluid as a coolant in a radiator)”, Applied Thermal Engineering , 30, 2010 9 John Vetrovec, Engine Cooling System with a Heat Load Averaging Capability, SAE International, 2008 10 M.H. Salah, P.M.Frick, J.R.Wagner, D.M.Dawson, Hydraulic actuated automotive cooling systemsNonlinear control and test, Control Engineering Practice, 17, 2009汽车散热器性能摘要：汽车发动机冷却系统是负责带走发动机运转过程中产生的多余的热量。它调节发动机的表面温度，来使发动机达到的最佳效率。最近随着发动机动力的发展迫使发动机冷却系统提出新的策略来改进其性能效率。也可以通过减少燃料消耗以及控制发动机排放，减轻环境污染。本文阐述了参数影响散热器性能以及评论的一些传统和现代的方法来提高散热器的性能。指数发动机冷却系统、性能、散热器一、介绍汽车发动机冷却系统负责发动机运转过程中产生的余热。它调节发动机表面温度对发动机最佳效率。大多数汽车发动机冷却系统由散热器、水泵、冷却风扇、压力上限和恒温器。散热器是系统的主要组件。散热器是一个热交换器,冷却液通过它带走发动机中的热量。热量从热冷却剂转移到外面的空气。散热器总成由三个主要部分组成核心,进口箱和出口。核心有两套,一套管子和风扇。冷却剂流过管子和风扇之间的空气流。热冷却剂将热量传递至风扇。外部空气通过风扇之间气流带走体内的热量。发动机冷却系统的性能的影响因素,比如空气和冷却剂质量以及流率,进气温度,冷却液,风扇类型、翅片间距、管式和管间距等。在设计冷却系统三个最基本的条件是基于以上参数。高海拔:在高空,空气密度低,因此会影响空气质量流率。夏天条件:在夏季周围空气是热即进气温度。最大力量:发动机最大功率的生产条件如车辆爬上坡时,最大热扭矩在这个条件是必需的。考虑所有这些因素，所需要的散热器核心尺寸可能很大。二、文献综述C. Oliet, A. Oliva, J. Castro, C.D研究不同因素影响散热器性能。它包括空气和冷却液流,风扇和空气入口温度。这是观察到散热器的传热和性能受到空气和冷却剂质量流率的影响很大。随着空气和冷却液流增加，冷却能力也增加。当空气进口温度的增加,传热,从而冷却能力降低。小翅片间距和更高的百叶窗式翅片角有较高的传热。风扇密度可以增加直到空气流动和传热速率降低。JP Yadav和 Bharat Raj Singh在他们的研究也提出了参数研究汽车散热器。在散热器的安装测试中得到散热性能参数。冷却剂的各种参数包括质量流率,进气冷却剂温度;等多种多样。以下评论期间观察研究:冷却液质量流量的冷却能力的影响散热器与冷却剂流量有直接关系。与冷却流量的价值,有相应增加的效果和冷却能力的价值。冷却液入口温度的影响提高入口温度的冷却液散热器的冷却能力增加。Mazen Al-Amayreh在他的研究中发现,经过测试乙二醇+水的热导率,二甘醇+水和三甘醇+水混合物,测量温度从25C到40C和浓度范围从25 wt%乙二醇75 wt%乙二醇。醇浓度的增加会导致热导率降低。增加混合物的温度能够少量的增加热导率。传统的或现代的方法都能够用来提高汽车发动机冷却系统的性能。传统的方法依赖于风扇,管和风扇设计优化。现代技术是基于新技术如纳米技术、热负荷平均容量或发动机冷却系统执行机构的建立。本文综述的一些传统和现代方法主要用来增强散热器性能。P. K. Trivedi, N. B. Vasava认为管间距的最佳配置能够让散热器发挥最高性能。传热表面积增加会改变散热器装配。这导致改变管子的几何形状或者通过修改汽车散热器的排布可以使表面积增加更好的传热。协议的修改管散热器是由学习管距的影响通过CFD分析使用它。结果表明,管间距的减少或增加比最佳距管,传热率降低。Pitambar Gadhve和Shambhu Kumar称使用凹槽提高强制对流传热表面。强化传热技术基于冷却液与凹槽的摩擦。表面凹槽促进流动和湍流混合增强传热。研究实验设置了带凹槽的和普通矩形的散热性能对比。实验结果与平面管对比之后,发现带有凹槽的传热增强。p . Gunnasegaran:h . Shuaib,mf和M. F. Abdul Jalal在他们的研究中说道在流体流动和传热特性数值模拟百叶窗角度紧凑热交换器。从流体计算域入口出口是解决。使用变量的影响百叶窗角度(+ 2,+ 4,-2,-4,和统一的角度20)变量和装有百叶窗板的鳍鳍球(1毫米,2毫米和4毫米)的热力和水力切。增加或减少的努塞尔特数较高百叶窗角度而统一的百叶窗角度。变量模式和百叶窗式翅片百叶窗角度较小;该应用能有效地提高传热性能与中度退化的压降比平翅片表面切处罚。Prof. D. K. Chavan, Prof. Dr. G. S.博士解释说传统散热器大小循环风扇难以覆盖矩形整个表面。它创造了低速度区角落给更少的热量转移。作者提出了消除角落和发展更为紧凑的圆形散热器,来提高效率,以便达到最小功耗驱动风扇和最大利用气流。考虑传统技术的局限性,提高冷却系统性能采用各种新技术。研究逐渐变成现实。K.Y. Leong, R. Saidur, S.N. Kazi, A.H. Mamun描述使用基于nanofluid冷却液在发动机冷却系统及其对冷却能力的影响。发现thatnano-fluid有更高的热导率比基础冷却剂50% / 50%水和乙二醇。它具有更好的导热性。对于相同的传热,散热器核心区域相比可以减少基地之一。找到更好的解决方案来减少区域。使用nanofluid散热器的热性能相比相同泵功率使用乙二醇作为冷却剂的散热器要好很多。John Vetrovec使用热负荷蓄电池发动机冷却系统的被动进行热负荷平均