Investigation of Heat Exchanger Effectiveness Using a Nano-Coating Technology

Allen Duffy, West Virginia University


Diesel engine manufacturers continue to improve engine performance through increased thermal efficiency and reduced regulated emissions. The aftercooler located between the turbocharger air outlet and intake manifold experiences a wide range of operating conditions. Improving the heat transfer characteristics in the aftercooler can lead towards improved engine performance through increased charge air density. A nano-based coating material has been proposed to enhance the heat transfer characteristics for a marine-based application on the water - side of the heat exchanger. To evaluate the efficacy of the nano-based coating, the rate of heat transfer with and without the nano-coating was quantified in a controlled laboratory environment utilizing a bench rig and an engine dynamometer test setup. The benchtop test rig was developed to represent the real-world operation of the aftercooler. Heat transfer rates were investigated by examining the difference of inlet and outlet temperatures in over 750 discrete operating conditions and five uncoated and coated cores using a benchtop test rig and an engine dynamometer. The primary goal of this study was to determine the heat transfer rate of a heavy-duty marine diesel engine aftercooler assembly with and without the nano-coating technology. To meet this goal, a benchtop test rig was developed for preliminary investigation and then validation and detailed characterization provided from testing a marine diesel engine. The benchtop test rig provided a platform to develop metrics for designing performance benchmarks. Data was collected under steady-state conditions, with inlet parameters of fluids being controlled to within ±2% moving averages of set point values. Analysis of data revealed no observable, repeatable differences to overall heat transfer between the uncoated and coated aftercooler cores. The average measurement uncertainty associated with all calculated values was ±3.7%, suggesting the benchtop test rig was capable of reliably quantifying the rate of heat transfer. Despite this, the results were within the margin of variation and were inconclusive for determining any significant changes resulting from application of the nano-coating technology.