No abstract

Intercoolers utilized in turbocharged engines are critically essential to efficiently improve volumetric efficiency and therefore engine's specific power. Although boosting the internal combustion engines has been extensively investigated, further studies are required to provide relevant approaches to optimize the heat transfer coefficient. This paper experimentally and theoretically investigates the influence of inlet coolant velocity on heat transfer characteristics of an air-to-water intercooler equipped in a turbocharged diesel engine. This aims to optimize the heat transfer rate from water to air under typical engine operating conditions. The experiment has been conducted using a fully equipped engine testbed. The engine is turbocharged with a plate-fin intercooler. The intercooler is a perpendicular air-water heat transfer system that could be suitable for boosted marine engines or power generators. A simulation model was also developed using the finite volume model in the ANSYS Fluent package. The distributions of inlet and outlet temperature, pressure, and velocity of air and coolant under various inlet water velocity and engine operating conditions are examined. The optimal heat transfer rate from air to water was achieved for this intercooler. The CFD simulation and experiment model developed here for the plate-fin water intercooler could be a useful approach to optimize other intercooler systems. In this study, with the 270×270×10 mm plate-fin perpendicular air-water intercooler, an optimal cooling water velocity of 1.0 m/s, corresponding with a flow rate of 1,780 liter/hr, is achieved.

<div class="section abstract"><div class="htmlview paragraph">In addition to the low cost and weight, the advantage of aluminum alloy heat exchangers over their counterparts is thanks to their anticorrosion, nonmagnetic, non-sparking, resilience, ductility at low temperature, high strength-to-weight ratio, high heat transfer coefficient, and easy fabrication. The advantages explain the currently popular utilization of aluminum alloy intercoolers in turbocharged engines. This study develops a finite volume simulation model using the computational fluid dynamics (CFD) available in the Fluent package to investigate the cooling efficiency for a cross-flow plate-fin intercooler system fabricated in this research. This is a cost-effective air-water heat exchanger made of thin aluminum alloy plates. The cross-flow plate-fin intercooler system was set up in this study using a perpendicular air-water configuration to cool down the hot air outlet from a turbocharger compressor equipped in a diesel engine. The engine with an intercooled turbocharger was tested in an AVL dynamometer testbed. The experiment results were used to validate the CFD model. An analysis was done for the heat transfer characteristic length, and 270 × 270 × 10 mm plates were selected to fit with the engine construction. The experiment was carried out for an eight-channel intercooler (four pairs of air and water channels) while the simulation model was developed only for two channels to reduce the computational cost. Numerical conversions were conducted to establish a model equivalent to the experimental one. The distributions of the inlet and outlet temperature, pressure, and velocity of intake air and coolant under various inlet water velocities and engine operating conditions were examined. This aims to optimize the heat transfer rate from water to air under engine-relevant operating conditions. The results show that the optimal cooling water velocity is 1.0 m/s corresponding with a flow rate of 1780 liter/hr. This approach could be useful to develop and/or optimize multichannel cross-flow plate heat exchangers for different applications including heat engines.</div></div>