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Technical Paper
2014-04-01
Jason Aaron Lustbader, Cory Kreutzer, Matthew A. Jeffers, Steven Adelman, Skip Yeakel, Philip Brontz, Kurt Olson, James Ohlinger
Abstract Cab climate conditioning is one of the primary reasons for operating the main engine in a long-haul truck during driver rest periods. In the United States, sleeper cab trucks use approximately 667 million gallons of fuel annually for rest period idling. The U.S. Department of Energy's National Renewable Energy Laboratory's (NREL) CoolCab Project works closely with industry to design efficient thermal management systems for long-haul trucks that minimize engine idling and fuel use while maintaining occupant comfort. Heat transfer to the vehicle interior from opaque exterior surfaces is one of the major heat pathways that contribute to air conditioning loads during long-haul truck daytime rest period idling. To quantify the impact of paint color and the opportunity for advanced paints, NREL collaborated with Volvo Group North America, PPG Industries, and Dometic Environmental Corporation. Initial screening simulations using CoolCalc, NREL's rapid HVAC load estimation tool, showed promising air-conditioning load reductions due to paint color selection.
Technical Paper
2014-04-01
B. Vasanth, Jose Bright, Pavan Reddy, Sathish Kumar S, Murali Govindarajalu
Abstract In an Automotive air conditioning system, the air flow distribution in the cabin from the HVAC (Heating, ventilation and air conditioning), ducts and outlets is evaluated by the velocity achieved at driver and passenger mannequin aim points. Multiple simulation iterations are being carried out before finalizing the design of HVAC panel duct and outlets until the target velocity is achieved. In this paper, a parametric modeling of the HVAC outlet is done which includes primary and secondary vane creation using CATIA. Java macro files are created for simulation runs in STAR CCM+. ISIGHT is used as an interface tool between CATIA and STARCCM+. The vane limits of outlet and the target velocity to be achieved at mannequin aim points are defined as the boundary conditions for the analysis. Based on the optimization technique and the number of iterations defined in ISIGHT, the vane angle model gets updated automatically in CATIA followed by the simulation runs in STARCCM+. Based on the results vane angle will get updated and the iterations continues automatically till the target velocity is met at the aim points.
Technical Paper
2014-04-01
Huize Li, Predrag Hrnjak
Abstract This paper presents an experimental study of lubricant effect on the performance of microchannel evaporators in a typical MAC system. R134a is used as the refrigerant with PAG46 lubricant. The increase of oil circulation rate elevates the pressure drop of the evaporator. The specific enthalpy change in evaporator decreases with increasing oil circulation rate, while refrigerant distribution appears to be more uniform as indicated by infrared images of the evaporator surface temperatures. Thus mass flow rate increases.
Technical Paper
2014-04-01
Kevin Cheung, Erich Becker
Abstract Vehicles with a large cabin volume incorporate two HVAC units to provide comfort to the front and rear cabin. Each HVAC unit can generate independent airflow volume, temperature, and airflow direction. A new HVAC unit was developed to achieve the performance and functionality of two HVAC units. A unique HVAC construction was used to achieve independent front and rear airflow volume, temperature, and airflow direction distribution. This integrated front and rear HVAC unit provides additional packaging space for other vehicle components and reduces the overall number of HVAC system components.
Technical Paper
2014-04-01
Neal Lawrence, Stefan Elbel
Abstract Two-phase ejectors are devices capable of recovering the expansion power that is lost by the throttling process in air conditioning cycles, resulting in improved system performance. High-pressure fluids such as CO2 have received the majority of attention in two-phase ejector studies in recent years due to the fluid's high throttling loss and high potential for improvement. However, low-pressure working fluids such as R134a, commonly used in automotive applications, have received considerably less attention owing to their lower recovery potential. While the two fluids have very different properties, both offer the potential for noticeable COP improvement with ejector cycles. Thus, understanding the operation and performance of ejectors with both fluids can be important to the design of ejector air conditioning cycles. This paper compares available experimental data for the performance of two-phase ejectors using CO2 and R134a. CO2 ejectors are capable of recovering a greater amount of power than R134a due to CO2's larger throttling loss as well as the ability of CO2 ejectors to recover a larger portion of the available power.
Technical Paper
2014-04-01
Kambiz Jahani, Sajjad Beigmoradi
Abstract Adequate visibility through the automobile windscreen is a critical aspect of driving, most often at very low temperatures when ice tends to be formed on the windscreen. The geometry of the existing defroster system needs to be improved in the vehicles, with the main aim of substantial increase in air mass flow reaching the windscreen through defroster nozzles and appropriate velocity distribution over the windscreen, while respecting all packaging constraints. The reason of this study is to investigate the windscreen deicing behavior of a vehicle by means of Computational Fluid Dynamics (CFD) with the main concern of improving deicing process by design an appropriate defroster. Two different defrosters with completely different geometry are considered for this purpose. A detailed full interior model of an existing vehicle is created via CAE tools. A transient simulation is performed and results are extracted to show how a proper design of the defroster will lead to considerable improve in deicing process.
Technical Paper
2014-04-01
Felix Regin A, Abhinav Agarwal, Niraj Kumar Mishra
Abstract Increased engine thermal load, front end styling and compact vehicle requirements have led to significant challenges for vehicle front end designer to provide innovative thermal management solutions. The front end cooling module design which consists of condenser, radiator, fan and intercooler is an important part of design as it ensures adequate heat removal capacity of radiator over a wide range of operating conditions to prevent overheating of engine. The present study describes the optimization of cooling air flow opening in the front end using CFD methodology of a typical passenger car. The predicted vehicle system resistance curve and coolant inlet temperature to the radiator are used for the selection of cooling modules and to further optimize the front end cooling opening area. This leds to the successful optimization of the front end, selection of cooling modules with significant cost savings by reducing prototype testing and design cycle time.
Technical Paper
2014-04-01
Carrie Kowsky, Edward Wolfe, Sourav Chowdhury, Debashis Ghosh, Mingyu Wang
Abstract With more vehicles adopting fuel-saving engine start-stop routines and with the number of hybrid and electric vehicles on the rise, automotive A/C (air conditioning) systems are facing a challenge to maintain passenger comfort during the time when the compressor is inactive due to engine shut down. Using PCM (Phase Change Material) in the evaporator enables it to store cold when the compressor is active and release it to the cooling air stream when the compressor is not running. A unique feature of Delphi's design is that a refrigerant thermosiphon mechanism inside the evaporator drives the energy transport between the PCM and air stream. Delphi's PCM evaporator extends comfort for short duration idle stops, reduces emissions, and increases fuel economy and electric drive range. In this paper, the design aspects of a thermosiphon based PCM cold storage evaporator are described and the performance and operation of the PCM evaporator in a MAC (Mobile Air Conditioning) system discussed.
Technical Paper
2014-04-01
Kristian Haehndel, Angus Pere, Torsten Frank, Frieder Christel, Sylvester Abanteriba
Abstract As computational methodologies become more integrated into industrial vehicle pre-development processes the potential for high transient vehicle thermal simulations is evident. This can also been seen in conjunction with the strong rise in computing power, which ultimately has supported many automotive manufactures in attempting non-steady simulation conditions. The following investigation aims at exploring an efficient means of utilizing the new rise in computing resources by resolving high time-dependent boundary conditions through a series of averaging methodologies. Through understanding the sensitivities associated with dynamic component temperature changes, optimised boundary conditions can be implemented to dampen irrelevant input frequencies whilst maintaining thermally critical velocity gradients. A sub-module derived from real vehicle geometry was utilised to evaluate a series of alternative averaging schemes (consisting of steady-state CFD points) in comparison to full CFD transient conditions.
Technical Paper
2014-04-01
Gianluca Montenegro, Augusto Della Torre, Angelo Onorati, Dalia Broggi, Gerd Schlager, Christian Benatzky
Abstract This work proposes a focus on the simulation of a rotative volumetric expander via a CFD code. A customized application of OpenFOAMĀ® has been developed to handle the particular motion of the calculation grid. The model uses a mesh to mesh interpolation technique, switching from a calculation grid to the new one on the basis of mesh quality considerations performed on the fly. This particular approach allows to account for the presence of leakages occurring between the stator and blade tips and also occurring at the top and bottom of the vanes. The fluid considered is the refrigerant R245fa, whose particular properties have been determined resorting to the NIST database. Experimental data, measured at different conditions of mass flow and fluid temperature, are compared to calculation results. Moreover, the CFD analysis has allowed the estimation of the influence of the leakage mass flow occurring at the tip of the vanes on the overall machine performances.
Technical Paper
2014-04-01
Jiazhen Ling, Magnus Eisele, Hongtao Qiao, Vikrant Aute, Yunho Hwang, Reinhard Radermacher
Abstract As a potential replacement to traditional automotive R134a direct expansion (DX) systems, a secondary-loop system allows for the usage of flammable but low-GWP refrigerants such as propane (R290). However, as the secondary-loop system has an additional layer of thermal resistance, the cycle's transient behavior and cabin thermal comfort during pull-down and various driving cycles may be different from traditional DX systems. This paper presents a Modelica-based model to simulate both steady-state and transient operation of automotive secondary-loop systems. The model includes a lumped cabin component and a secondary-loop automotive air-conditioning system component. The air-conditioning system component consists of a condenser, a compressor, an expansion device, a coolant plate type heat exchanger, a coolant to air heat exchanger and a coolant pump. The developed model was validated against both steady-state and transient experimental data for an R290 secondary-loop system. The steady-state comparison demonstrates a 7.5% deviation of air-side COP compared to the experimental data.
Technical Paper
2014-04-01
Kristian Haehndel, Anthony Jefferies, Markus Schlipf, Torsten Frank, Frieder Christel, Sylvester Abanteriba
Abstract At the rear of the vehicle an end acoustic silencer is attached to the exhaust system. This is primarily to reduce noise emissions for the benefit of passengers and bystanders. Due to the location of the end acoustic silencer conventional thermal protection methods (heat shields) through experimental means can not only be difficult to incorporate but also can be an inefficient and costly experience. Hence simulation methods may improve the development process by introducing methods of optimization in early phase vehicle design. A previous publication (Part 1) described a methodology of improving the surface temperatures prediction of general exhaust configurations. It was found in this initial study that simulation results for silencer configurations exhibited significant discrepancies in comparison to experimental data. This was mainly due to the inability to represent complex fluid flows through the components of the silencer, which was greatly simplified in the simulation models and software utilised.
Technical Paper
2014-04-01
Shi-Ing Chang, Iman Goldasteh, Salamah Maaita, Gursaran Mathur
Abstract The performance of an automobile engine depends on the adequate heat rejection through the radiator assembly. Despite of the existence of well-known theoretical models for various heat transfer applications, design of heat exchanger devices demands tremendous experimental work and effort. This study concerns the use of computational fluid dynamics (CFD) to analyze the heat transfer and fluid flow in finned tube heat exchangers which are widely used in automotive industries. Here, two different types of the finned tube heat exchangers were studied using the Star-CCM+ commercial CFD package. Because of the symmetric nature of the geometry, only a single fin was considered in simulations. Two different designs of finned tube heat exchanger were considered in the analysis and major attention was given to the fin configurations, louvers number and louvers angle. Although the contact surface of the fin to the coolant tube is different, the thermal performance was not affected under present steady state analysis.
Technical Paper
2014-04-01
Zun Wang, Jaehoon Han, Devadatta Mukutmoni
Abstract At the onset of soak, air and surface temperatures in an engine bay enclosure are elevated since temperature of heat sources are high while convective cooling is sharply reduced as a result of airflow being shut off from the inlet grilles of the vehicle leading to temperature spikes. Accurate simulation of this important thermal and flow regime that is natural convection driven, highly transient and complex is therefore very important. In this investigation, we simulate flow in the engine bay at the onset of soak with fixed thermal boundary conditions where the geometries representing the engine bay and components are simplified. Good agreement was observed with detailed experimental data available in references for both velocities and temperatures.
Technical Paper
2014-04-01
Alaa El-Sharkawy
Abstract Computational tools have been extensively applied to predict component temperatures before an actual vehicle is built for testing [1, 2, 3, 4, and 5]. This approach provides an estimate of component temperatures during a specific driving condition. The predicted component temperature is compared against acceptable temperature limits. If violations of the temperature limits are predicted, corrective actions will be applied. These corrective actions may include adding heat shields to the heat source or to the receiving components. Therefore, design changes are implemented based on the simulation results. Sensitivity analysis is the formal technique of determining most influential parameters in a system that affects its performance. Uncertainty analysis is the process of evaluating the deviation of the design from its intended design target. In the case of thermal protection, uncertainty analysis is applied in order to determine the variation of the calculated component temperature around its nominal value.
Technical Paper
2014-04-01
Vinod Kumar Srinivasa, Renjith S, Biswadip Shome
Abstract Increasing demands on engine power to meet increased load carrying capacity and adherence to emission norms have necessitated the need to improve thermal management system of the vehicle. The efficiency of the vehicle cooling system strongly depends on the fan and fan-shroud design and, designing an optimum fan and fan-shroud has been a challenge for the designer. Computational Fluid Dynamics (CFD) techniques are being increasingly used to perform virtual tests to predict and optimize the performance of fan and fan-shroud assembly. However, these CFD based optimization are mostly based on a single performance parameter. In addition, the sequential choice of input parameters in such optimization exercise leads to a large number of CFD simulations that are required to optimize the performance over the complete range of design and operating envelope. As a result, the optimization is carried out over a limited range of design and operating envelope only. In this paper, a Design of Experiments (DoE) based CFD approach has been used to optimize the fan and fan-shroud design of a cooling pack system.
Technical Paper
2014-04-01
Fabien Rabeau, Sebastien Magand
Abstract Thermal management is a key issue to minimize fuel consumption while dealing with pollutant emissions. It paves the way for developing new methods and tools in order to assess the effects of warm up phase with different drivetrains architectures and to define the most suitable solution to manage oil and coolant temperatures. DEVICE (Downsized hybrid Diesel Engine for Very low fuel ConsumptIon and CO2 Emissions) project consists in designing hybrid powertrain to cut off significantly CO2 emissions. It combines a 2-cylinder engine with an electric motor and a 7-gear dual clutch transmission. Hybridization and downsizing offer a great improvement of fuel economy and it is valuable to study their effects on thermal management. Hence, a dedicated AMESim platform is developed to model the fluids temperatures as well as the energy balance changes due to the powertrain architecture. After using a 4-cylinder reference engine to validate the model, the warm up phase (comparing hot and cold start NEDC) leads to a 12% fuel consumption penalty with DEVICE powertrain.
Technical Paper
2014-04-01
Ram Iyer, Jin Zhou, Li Lu, Jeffrey Webb, Qaiser Khan
Abstract A CAE simulation methodology was developed to predict the warpage and shape deviation from nominal in finished plastic sub-assemblies that are joined using Infra-Red (IR), hot-plate or vibration welding processes. An automotive glove box bin and door sub-assembly was used to develop the methodology. It was seen that part warpage from injection molding and welding causes warpage in final assembled product which results in gaps and the consequent loss in quality of appearance. The CAE simulation methodology included prediction of the part warpage with residual stress from the injection molding process, use the post-molded shape as an initial part condition for the welding process, and simulation of the welding process itself. The welding process simulation included fixturing of the parts in the welding process, localized heating in the case of an IR welding process, fusion of the parts at the weld locations and thermal creep resulting in long term stress and shape relaxation of the part.
Technical Paper
2014-04-01
Mohammed K Billal, Vinothkumar Subramani, Mohan Rao, Tim Potok
Abstract An automotive cockpit module is a complex assembly, which consists of components and sub-systems. The critical systems in the cockpit module are the instrument panel (IP), the floor console, and door trim assemblies, which consist of many plastic trims. Stiffness is one of the most important parameters for the plastic trims' design, and it should be optimum to meet all the three functional requirements of safety, vibration and durability. This paper presents how the CAE application and various other techniques are used efficiently to predict the stiffness, and the strength of automotive cockpit systems, which will reduce the product development cycle time and cost. The implicit solver is used for the most of the stiffness analysis, and the explicit techniques are used in highly non-linear situations. This paper also shows the correlations of the CAE results and the physical test results, which will give more confidence in product design and reduce the cost of prototype testing.
Technical Paper
2014-04-01
Ayse Ademuwagun, Joel Myers
Abstract Coconut shell and torrefied wood are bio-sourced and renewable materials that can be used as fillers in various polymer matrices. Torrefied wood material can be produced from numerous cellulose based materials, such as wood, sunflower hulls, flax shive, hemp and oat hulls. These bio-fillers would replace talc and glass bubbles which are not a renewable resource. Additionally, the implementation of torrefied wood and coconut would reduce the carbon footprint and improve sustainability of Hyundai and Kia vehicles, improving customer perception of our product line. In this study, coconut and torrefied wood filled polypropylene properties are tested for a HVAC Case application.
Technical Paper
2014-04-01
Venkat Pisipati, Srikanth Krishnaraj, Edgar Quinto Campos
Abstract Motor vehicle safety standards are getting to be more demanding with time. For automotive interiors, instrument panel (IP) head impact protection is a key requirement of the Federal Motor Vehicle Safety Standard (FMVSS) 201. To ensure compliance of this requirement, head impact tests are conducted at 12 and 15 mph for performance verification. Computer simulation has become more prevalent as the primary development tool due to the significant reduction in time and cost that it offers. LS-DYNA is one of the most commonly used non-linear solvers in the automotive industry, particularly for safety related simulations such as the head impact of automotive interiors. LS-DYNA offers a wide variety of material models, and material type 024 (MAT 024, piecewise linear plasticity) is one of the most popular ones [1]. Although it was initially developed for metals, it is commonly used for polymers as well. LS-DYNA also offers several other material models specifically developed to simulate polymers, such as material types 019, 089, 123, to name a few.
Technical Paper
2014-04-01
Ashok Mache, Anindya Deb, G.S. Venkatesh
Abstract Natural fiber-based composites such as jute-polyester composites have the potential to be more cost-effective and environment-friendly substitutes for glass fiber-reinforced composites which are commonly found in many applications. In an earlier study (Mache and Deb [1]), jute-polyester composite tubes of circular and square cross-sections were shown to perform competitively under axial impact loading conditions when compared to similar components made of bidirectional E-glass fiber mats and thermo-setting polyester resin. For jute-reinforced plastic panels to be feasible solutions for automotive interior trim panels, laminates made of such materials should have adequate perforation resistance. In the current study, a systematic characterization of jute-polyester and glass-polyester composite laminates made by compression molding is at first carried out under quasi-static tensile, compressive and flexural loading conditions. Low velocity impact perforation tests at speeds of around 4 m/s are then performed in an instrumented drop-weight testing device on square plates extracted from the same laminates.
Technical Paper
2014-04-01
Egon Moos
Abstract In today's vehicles underbody parts are absolutely necessary to reach a certain performance level regarding fuel saving, corrosion protection, driving performance and exterior as well as interior noise. With the constant demand for additional parts, which means additional weight on the car, lightweight materials have come more and more into the focus of development work. LWRT (low weight reinforced thermoplastic) is the acronym for this material group. The ongoing success of such materials in underbody applications that compared to compact materials such as GMT (glass mat reinforced thermoplastic) is the weight saving of up to 50 %, or in other words, with LWRT you can cover twice as much surface then with GMT. The production process is compression molding, but with low pressure because LWRT-material needs only partial compact areas, most regions of these parts can have a density even below 0.5 g/cm3. Another advantage coming with the process is the possibility to use multi-cavity tools, so a high volume production becomes very economical.
Technical Paper
2014-04-01
Zheng Zhong Wang, Youzhong Xu, Kuaichu Fan, Binglin Da
The series of work introduced in this paper is originated from a structural failure of the vehicle A/C (Air-Conditioner) pipe, and when many possible factors having been excluded, the main investigating endeavor is focused on RLD acquisition and analysis, which eventually leads to the successful design improvement. During this process, many important signal collectives, such as micro-strains, accelerations, and engine speed are provided by RLD acquisition in some predefined conditions. Subsequently, these signals are analyzed both in time and frequency domain. Furthermore, order analysis by correlation of acceleration and engine speed is also performed to find a definite reason. As a conclusion, the root cause to the crack is not excitation from the road, but mainly from the engine. Based on this conclusion, structure design is improved and is theoretically proved to be effective by the RLD comparison analysis. And the quantified validation to this work is given by the real road test finally.
Technical Paper
2014-04-01
Mitsuru Enomoto, Michiko Kakinuma, Nobuhito Kato, Haruo Ishikawa, Yuichiro Hirose
Abstract Design work for truck suspension systems requires multi-objective optimization using a large number of parameters that cannot be solved in a simple way. This paper proposes a process-based systematization concept for ride comfort design using a set-based design method. A truck was modeled with a minimum of 13 degrees of freedom, and suspension performance under various vehicle speeds, road surface conditions, and load amounts was calculated. The range of design parameters for the suspension, the range of performance requirements, and the optimal values within these ranges were defined based on the knowledge and know-how of experienced design engineers. The final design of the suspension was installed in a prototype truck and evaluated. The performance of the truck satisfied all the objectives and the effectiveness of the set-based design approach was confirmed.
Technical Paper
2014-04-01
Shuming Chen, Dengzhi Peng, Dengfeng Wang
Abstract Automobile cabin acoustical comfort is one of the main features that may attract customers to purchase a new car. The acoustic cavity mode of the car has an effect on the acoustical comfort. To identify the factors affecting computing accuracy of the acoustic mode, three different element type and six different element size acoustic finite element models of an automobile passenger compartment are developed and experimentally assessed. The three different element type models are meshed in three different ways, tetrahedral elements, hexahedral elements and node coupling tetrahedral and hexahedral elements (tetra-hexahedral elements). The six different element size models are meshed with hexahedral element varies from 50mm to 75mm. Modal analysis test of the passenger car is conducted using loudspeaker excitation to identify the compartment cavity modes. All the acoustic cavity models are coupled with the structure model respectively, the cavity modes are calculated with structural-acoustic coupling model.
Technical Paper
2014-04-01
Prasad Kumbhar, Ning Li, Peijun Xu, James Yang
In vehicle driving environment, the driver is subjected to the vibrations in horizontal, vertical, and fore-aft directions. The human body is very much sensitive to whole body vibration and this vibration transmission to the body depends upon various factors including road irregularities, vehicle suspension, vehicle dynamics, tires, seat design and the human body's properties. The seat design plays a vital role in the vibration isolation as it is directly in contact with human body. Vibration isolation properties of a seat depend upon its dynamic parameters which include spring stiffness and damping of seat suspension and cushion. In this paper, an optimization-based method is used to determine the optimal seat dynamic parameters for seat suspension, and cushion based on minimizing occupant's body fatigue (occupant body absorbed power). A 14-degree of freedom (DOF) multibody biodynamic human model in 2D is selected from literature to assess three types of seat arrangements. The human model has total mass of 71.32 kg with 5 body segments.
Technical Paper
2014-04-01
Chao Ding, Zhibao Xu, Yunqing Zhang, Qiming Tao
Abstract Vehicle Thermal Management System (VTMS) is a cross-cutting technology that directly or indirectly affects engine performance, fuel economy, safety and reliability, driver/passenger comfort, emissions. This paper presents a novel methodology to investigate VTMS based on Modelica language. A detailed VTMS platform including engine cooling system, lubrication system, powertrain system, intake and exhaust system, HVAC system is built, which can predict the steady and transient operating conditions. Comparisons made between the measured and calculated results show good correlation and approve the forecast capability for VTMS. Through the platform a sensitivity analysis is presented for basic design variables and provides the foundation for the design and matching of VTMS. Modelica simulation language, which can be efficiently used to investigate multi-domain problems, was used to model and simulate VTMS.
Technical Paper
2014-04-01
Betty Belhassein, David Chalet, Pascal Chesse, Guillaume Alix, Romain Lebas
Abstract Emission regulations have become increasingly stringent in recent years. Current regulations need the development of a new worldwide driving cycle which gives greater weight to the pollutants emitted during transient phases or cold starts. Powertrains contain a large number of components such as multistage turbocharger systems; exhaust gas recirculation, after-treatment devices and sometimes an electric motor. In this context, 0D predictive models of heat transfer in the exhaust line, calibrated with experimental data, are particularly interesting. Many investigations are related to the development of precise control laws in order to optimize the light-off of after-treatment elements during the engine starting phase. A better understanding of the thermal phenomena occurring in the exhaust line is necessary. To study the heat transfer in the exhaust line of a Diesel engine during transient conditions, the temperature in the exhaust line must be known precisely. The experimental methodology followed by the authors contains three steps: first, temperature and pressure drops are made on a pulse generator to characterize properly each thermocouple (four different diameters).
Technical Paper
2014-04-01
Md Abdul Quaiyum, Mohammed Ismail, Amir Fartaj
Abstract Channel diameter is one of the most important parameters of a heat exchanger especially for a highly viscous fluid-flow. Narrow channel heat exchangers are believed to have better energy efficiency due to elevated heat transfer characteristics. Heat transfer and Fluid-flow behaviors of Automatic Transmission Fluid (ATF) have been experimentally investigated in a closed loop integrated thermal wind tunnel test facility using wavy finned Minichannel Heat Exchanger (MICHX). The experiment was conducted by varying the ATF Reynolds number from 3 to 30. The flow friction factors in minichannel were evaluated. For a fully developed laminar flow the friction factors were evaluated considering fluid viscosity effects due to temperature variation. The flow correlated with a Poiseuille equation while friction factors were analyzed considering constant property ratio. However, it showed different correlation when considered variable property ratio. A numerical analysis on friction factor for single serpentine MICHX did not follow the Poiseulle law for both cases of constant property ratio and variable property ratio.
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