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The use of aluminium alloys in automotive heat exchangers, including both engine cooling and air conditioning systems, is now well established for vacuum, and more recently, non corrosive flux brazing. There is a growing trend towards greater weight saving and, thus, increasing the mechanical, thermal and corrosion performance of the heat exchanger. This has placed greater demand on improving material properties for tubestock, platestock and finstock for radiators and other types of heat exchanger units. This paper discusses some of the key material developments within Alcan Rolled Products UK to meet these growing demands from the automotive heat exchanger industry and, in particular the need to select material systems to meet the requirements of individual applications.

The market needs for quieter engine cooling modules and the upcoming stringent noise level regulations have led Valeo to develop a series of numerical codes which will give the fan designer accurate noise predictions and will also ideally complement its CFD simulation based design for its future fan technology [1]. The current approach involves three levels of noise prediction: first a global sound pressure level estimate which will use the fluid 2D CFD blade cascade information; secondly, a spectral distribution which relies on fan loads to provide a first estimate of the subjective noise; finally, a temporal approach based on the Ffowcs-Williams theory which will come the closest to the actual measurements and will fully use the 3D CFD fan data. Validation calculations and first predictions have shown that, even if an accurate absolute noise level cannot always be obtained (within 1 dBA), observed experimental trends are already well captured.

The durability of an aluminium heat exchanger in a corrosive environment depends on the composition and combination of component materials. and the rate at which corrosion occurs will be influenced by the metallurgical and electrochemical characteristics of the individual components Using a simple multiple anodic polarising technique it has been possible to establish both the electrochemical characteristics of component materials. The results from experimental data have been used to design heat exchangers Accelerated corrosion testing of these heat exchangers confirmed predicted corrosion durability.

This paper deals with engine evaporative cooling on the VW TDI diesel engine at high heat rejection running points. Engine tests and thermohydraulic 3D computations inside the engine head are used. First, the basic engine is studied. Then, the flow rate corresponding to evaporation is determined. Around this flow rate, the influence of inlet coolant temperature and circuit pressure are studied. The engine tests and 3D calculations give hydraulic ways of improvements consisting in balancing the flows around the different cylinders. Geometrical modifications of the inside engine circuit (gasket....) are then tested to achieve these improvements.

Cooling fan performance: pressure rise, flow rate, shaft power have been acquired. The control variables for these measurements include the fan rprn and the relative immersion of the fan into the shroud. In addition tuft visualizations and hot-wire anemometry have been used to visualize and measure the velocity field in the wake of the fan. The velocity measurements have been processed to provide phase averaged mean and RMS fluctuation levels. The mean values have been differentiated to provide the phase averaged streamwise vorticity magnitudes. The data are used to gain an understanding of the fluid mechanical attributes of the flow field, as well as to provide experimental results for comparison with computational investigations.

A new control algorithm for future use in an ECC (Electronic Climate Controller) has been developed. To overcome the problem of having many controller inputs and outputs, we used a method of breaking down the problem to a one dimensional one; the method was named the quantifier-selector method. As the name suggests it consists of a quantifier part and a selector part; the quantifier calculates ‘how much’ heating or cooling is needed; the result from the quantifier is used in the selector when deciding ‘how’ to achieve this cooling/heating. The quantifier consists primarily of a rather unconventional nonlinear PI controller and some feedforward compensations. The selector is mainly made up of static mappings. The algorithm was tuned using simulations and rapid prototyping techniques in a climatic wind tunnel and during road tests. The performance of the system has been satisfactory and also a significant energy saving could be verified.

The process of developing an energy efficient climate controller (EECC) is described. The purpose of the project was to reduce the energy consumption of the climate system in a car, still fulfilling the requirements of climate comfort in the car compartment. The energy efficiency of the EECC was determined by measuring the fuel consumption of the car at various climate conditions in the controlled environment of a climatic wind tunnel. The measurements show that the EECC reduces the fuel consumption by 1.6 % compared to an ECC (Electronic Climate Controller) of an existing production vehicle, when driven for one year in a European climatic zone.

To determine the true galvanic compatibility of radiator components a test has been developed using a zero resistance ammeter (ZRA) technique, which measures the magnitude of the galvanic current between different materials, thus allowing specific corrosion rates to be calculated. It is believed that the use of the ZRA technique will help provide a better balance between sacrificial behaviour and thermal performance of fin alloys. In particular, it will be demonstrated that it is not necessary to make additions of zinc to the fin alloys to attain a sacrificial effect, which in the longer term may compromise the recyclability of radiator units.

In this study, the air flow through the complete HVAC system (Heating-Ventilation-Air-Conditioning system) together with the flow field in the passenger compartment of a new Mercedes is calculated using the commercial CFD program STAR-CD. Two operating conditions of the HVAC system have been considered, namely the standard winter heat-up and summer cool-down mode. The computational model consists of around 6 million cells and includes all parts of the HVAC system (inlet plenum chamber, fan, filters, air distribution chamber with evaporator and heater, air ducts and vents) together with a detailed description of the passenger compartment containing four occupants.

The cooling fan is a vital part of a vehicle cooling system. A fan is normally tested as a component in a chamber rig. But component testing of the fan does not reflect the geometry encountered in the vehicle. System performance and engine compartment air flow distribution is difficult to predict due to the strong interaction between fan and installation geometry. This investigation is an attempt to break down the problem step by step. The flowfield at fan inlet is investigated with CFD for different geometries. The fan was tested both with and without an engine mock up behind the fan to see the influence on the fan curve. The fan flow field was measured with LDA in the vehicle with a working fan. The data was evaluated by flow calculations with a streamline curvature method.

A new fin material, FA6815 (AA3003+Si, Zn, Zr) which corrodes at a low rate and gives cathodic protection to 3005LL tubes and AA4343 braze filler is presented. It shows better sagging resistance and twenty per cent higher post-braze strength than conventional AA3003 and AA3003+Zn. A new age hardening material, FA7827 (AlMgSi-type) for header and side supports is also presented. It has tensile strength of 180 MPa after brazing and fifteen days natural ageing. The corrosion resistance is improved compared to AA3003 and AA6060. These two new materials in combination with 3005LL tubes allow for improved performance and cost benefits by downgauging.

Valeo Thermal Systems is developing a software package for the design and simulation of a car air-conditioning systems. This software package aims to improve Valeo's response to customer requirements concerning delays for design and sizing system performance and cost reduction.Further it shall help to capitalise our competece and expertise on the A/C systems. The validation of this software is in progress. The software is made up of two modules: A first module for car cabin thermal simulation in dynamic and stationary regimes. A second module for the determination and optimisation of the components for designing an A/C system. A third module is under development for the dynamic simulation of the A/C system functioning in nonstandard conditions.

A new and unique facility has been developed at the Turbulent Shear Flows Laboratory at Michigan State University for the study of automotive cooling fans. Performance data can be acquired for a variety of fan and component geometries using this facility. Additionally, detailed velocity measurements can be made in the wake of the fan. This paper describes the details of the facility with examples of the data that can be acquired.

A complementary heating system uses components of an A/C loop. Hot refrigerant vapour is injected in the evaporator where it heats up the airflow penetrating the passenger cabin. The energy is provided by the compressor compressing the refrigerant against a gas expansion device. A 3 -way diversion valve makes it possible to switch between the classical A/C operation and the new additional heating function. The Additional Heating System (AHS) has been installed on cars and tested in a climatic windtunnel and during field tests.

The use of copper heat exchangers was the major trend in large transportation vehicles due to their satisfactory performance in severe conditions. However, heat exchangers made of aluminum for the heat exchanger part and glass-fiber reinforced modified polyamide resin for the coolant tank have been developed due to the demand for weight and cost reduction as well as productivity improvement. In the injection molding of these large tanks, warping is an engineering concern. Therefore, by analyzing the warping with the use of injection molding simulations, we have developed a production method that is capable of satisfying the dimensional requirements without any dimension correcting process.

Tests have been conducted to evaluate materials suitable for headers of CAB brazed aluminum radiators, particularly as concerns pressure cycle endurance. These tests were done on different alloy compositions, for both standard and proprietary versions from series 6000 and 3000, with or without post-braze heat treatment. The results from those tests have helped to evaluate the influence of various material characteristics over the pressure cycling resistance. In particular, they have shown that post-braze yield strength was not the only parameter to consider. It appeared also that none of the materials tested could give good results for all designs and test conditions, but, at least, this study has helped to state more precisely what the contents of a specification for an ideal material should be.

Characteristics of fluid flow and heat transfer in an automotive HVAC module was investigated to analyze some important design issues. Distribution of air flow rate and air temperature at the outlets of the module and duct were analyzed by using a Computational Fluid Dynamics (CFD) procedure. A standard k-ε turbulence model with the Upwind Differencing convection scheme was used on a properly refined computational grid. Comparison with the experimental data of air flow rate distribution and temperature at the outlets showed that the CFD procedure can be a very useful design tool for an automotive HVAC system.

This paper compares numerical results of the flow through an axial fan with measurements. A typical nine bladed engine driven fan is modeled using grid refinement techniques in order to maintain good resolution at the fan blades while also including the extent of the test fixture. In the calculations a multiple reference frame approach, a transient moving mesh and a body force model are investigated. At a fixed fan speed discharge and pressure rise were measured in the test facility and a series of numerical simulations were made over the same range of conditions. A comparison of the two discharge curves shows fairly good agreement.

A numerical method was developed to establish a procedure for an axial flow fan design. Theory of free/force vortex motions, boundary element methods and optimization methods were applied to conduct this process. Rotational speed, ambient temperature and pressure were used as the input data; and tip diameter, hub diameter, number of blade, flow rate, static pressure, and vortex motion were initially guessed and employed to compute the design parameters. These design parameters included lift and drag of an airfoil profile, inlet angle and velocity, outlet angle and velocity, and variation of axial velocity in the radial direction. The optimization of tip diameter, hub diameter, number of blade, chord, and stagger angles at different radii were calculated as the numerical results. Computational solutions of the stagger angles in the radial direction were compared with those of the Valeo's current products. Agreement of the comparison of the stagger angle is reasonable.

The targets of this study are: cost reduction of all engine cooling components, gasoline consumption reduction, weight reduction of the engine cooling system, improvement of the thermal comfort in passenger compartment. To reach these targets, Valeo Engine Cooling is developing a new concept in engine cooling. This basic concept consists of adding a small electric water pump, 30 to 60W, instead of the conventional engine driven water pump of up to 1 to 2 KW. This small electric water pump provides a flow rate of approximately 1000L/h. With a liquid flow rate of 1000L/h, this conceptual system can ensure engine cooling at speeds up to 120 Km/h under convective cooling in normal conditions. That is to say, it can supply 95% of the flow requirements (see appendix ) of a vehicle at the same performance level as a conventional cooling system.