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Technical Paper

Acidic Condensation in HP EGR Systems Cooled at Low Temperature Using Diesel and Biodiesel Fuels

In order to further reduce NOx emissions in increasing HP EGR cooler performance, several OEMs have decided to use a secondary cooling loop dedicated to bring cold water (around 35°C) to the HP EGR heat exchanger. Nevertheless, strongly cooled EGR gases can condensate in the cooler-producing acidic liquids which can corrode some parts in the loop. It is therefore necessary to define EGR components compatible with such kind of environment and constraints. Testing was performed on a 2.0-liter EU4 diesel engine, using a large panel of current fuels including neat biodiesels from soybean, rapeseed or palm, as well as low and high sulfur petroleum-based diesels. In order to cover all existing cycle conditions, the HP EGR is cooled from 20°C to 90°C independently from the engine coolant circuit.
Technical Paper

Cooled EGR for a Turbo SI Engine to Reduce Knocking and Fuel Consumption

Cooled exhaust gas recirculation is emerging as a promising technology to address the increasing demand for fuel economy without compromising performance in turbocharged spark injection engines. There are a number of different possible architectures, each with its specific characteristics. The objectives of this study are to quantify the increase in knock resistance and to decrease the enrichment at full load in order to target stoichiometric operation over the full operating range, and to define a vehicle compatible cooling system to meet the demanding heat rejection requirements. Based on our knowledge in EGR and air loops, the benefits and risks of various cooled EGR turbocharged systems were evaluated and compared in a preliminary phase. Two architectures, one with high pressure EGR and the other with low pressure EGR, were selected and tested on a 2L turbocharged gasoline engine on a stationary test bench and the performance was compared to the serial production engine.
Technical Paper

Heat Transfer in Minichannels Tubes for Automotive Evaporator

The recent evolution in automotive evaporator technology with multiport flat tubes replacing the plates has lead to new heat transfer pattern on the refrigerant side. Common used correlations can no longer be applied to model the heat transfer coefficient and new developed correlations are often limited to experimental conditions. This study presents a state of the art as well as a comparison of experimental results to these new correlations.
Technical Paper

Electrochemical Behavior of Brazed Aluminum Alloys Used in Automotive Heater Cores

The aim of the present paper was to discuss, on the basis of electrochemical results and microscope observations, the representativeness of the Nissan OY water test (acidic solution containing chloride) used to evaluate the internal corrosion resistance of heat exchangers from the cooling loop. The corrosion behavior of brazed aluminum alloys (AA4343/AA3003*/ AA4343) was investigated in neutral and acidic solutions with and without chloride by electrochemical measurements. For the three layers present in the brazed material, i.e. the residual cladding, the band of dense precipitates (BDP) and the core material unspoiled by silicon diffusion, the polarization curves were obtained in the different media. It was observed that the core material presented good corrosion resistance in neutral solutions.
Technical Paper

Structural Modeling and Optimization of Circular Tubes in A Mechanically Assembled Condenser

Recently mechanically assembled heat exchangers became attractive due to their cost advantage. The optimization of the tube structure was in demand because test results showed that the current tubes used in the mechanical heat exchanger may not be optimized. The objective of this study is to find sophisticated and effective structural modeling techniques so that optimization studies can be performed. Two methodologies were used in the study with a focus on the load distribution and the load sharing mechanisms between the tube and the surrounding fins. The first method is performed by analysis of the mechanics in a simple model. The close-form solutions provided explicit relationships between the load applied and the stresses generated. The second method used is a computer generated finite element analysis (FEA) model with more consideration to geometric details, material non-linearity, and boundary conditions.
Technical Paper

Optimization of Fin Louver Design Based on CFD

This paper presents an optimization methodology for the design of fin louvers of compact heat exchangers based on 2-D CFD calculations. The mesh generation and its automatization is described. The validation of the methodology and the results of this validation are presented. Finally, an example of application is given.
Technical Paper

Truck Airflow Management Influence on Cooling Module Performance - Experimental and Numerical Study

The objective of this paper is to present a methodology for the cooling system optimization based on experimental and numerical studies. Experimental measurements of fan performance for several truck fans have been carried out in order to determine the representative fan curves. These fan curves have been used to numerically simulate the performance of a truck cooling module consisting of heat exchangers and fan. The cooling module performance optimization has been carried out considering different fans, fan pumping power and fan overdrive ratios. The fan shroud has great influence on the cooling air flow distribution across the exchangers. The test bench has potentials to test a charge air cooler and a radiator at the same time simulating different truck operating conditions. In order to investigate the influence of different shrouds on the performance, experimental measurements and numerical study have been done for several module configurations.
Technical Paper

Exhaust heat exchange in a pipe of an internal combustion engine~EGR cooler and passenger compartment heating applications

The exhaust heat exchange coefficient in a pipe of internal combustion engine has been measured with a specific exhaust-air heat exchanger. It''s installed on the exhaust line of IC engine. The Nusselt-Reyonlds correlation has been developed and compared to the steady-state conditions known as Colburn''s correlation. The Convective Augmentation Factor (CAF) is approximately 2 at low Reynolds number and 1 at high Reynolds number. The technology of EGR cooler and the exhaust-coolant heat exchanger for improving the thermal comfort have been shown. A vehicle equipped with a direct-injection turbo diesel engine has been tested in the climatic wind tunnel. The heat performance in the passenger compartment will be presented.
Technical Paper

Automatic Control of Electronic Actuators for an Optimized Engine Cooling Thermal Management

The main objectives of new technologies for internal-combustion engine are lower consumption, pollutant reduction and comfort passenger increase. To reach these objectives, we have adopted for engine thermal management two strategies: quicker rise temperature during the cold start and higher engine temperature for part load. To satisfy these criteria, we have modified the classic cooling loop. An electric water pump, an electric water valve and variable speed fan system are the new actuators automatically controlled by electronic calculator. This concept allows to obtain a warm-up time reduced by 50% and 2 to 3% fuel economy on the European cycle.
Technical Paper

Advanced Engine Cooling Thermal Management System on a Dual Voltage 42V-14V Minivan

Today the worldwide convergence towards stricter fuel consumption and emission regulations is pushing carmakers and suppliers into new fields of innovation. Valeo Engine Cooling, VEC, is contributing towards these goals by applying its thermal management system expertise in order to reduce fuel consumption and emissions by using an advanced engine cooling system that incorporated variable speed PWM fans, an electric water pump and an electric water control valve. The paper discusses the benefits in terms of engine cooling, fuel economy and emissions over the FTP drive cycle. The paper gives some examples of advanced engine cooling strategies based on a virtual, predictive metal temperature sensor that is used to actuate the electrical water pump at the desired flow rate. The electrical balance between the 42V pump and fans has also been optimized to reduce the vehicle electrical power consumption and to keep the coolant temperature close to 110°C.
Technical Paper

In Vehicle Cooling Module Performance Prediction - PC Program Features

This paper describes a PC based computer program, NSYSDES (new system design), that will rate a vehicle cooling module including up to five fluid to air components, a fan with shroud and vehicle ram air. It is intended for use by sales and applications engineers who need quick yet reliable ratings of proposed systems to respond to a sales quotation. Given complete package and component geometry specifications, component dimensionless surface friction and heat transfer characteristics and inlet conditions, this program will yield outlet temperatures and system air side pressure drop as primary results. Stressed are user entries and program options rather than in-depth technical descriptions.