Model-Based Design of Triple-Screw Pump for Automotive Engine Cooling

Fuel saving and, consequently, CO2 emissions reduction are the main driver of internal combustion engine development for the transportation sector. Among the several technological options presently available for this purpose, those related to thermal management and, in particular, engine cooling optimization, seem to have additional value thanks to their easiness to be applied on board, without invasive modification of the engine and the vehicle. Typically, centrifugal pumps are adopted, but their efficiency is highly dependent on their revolution speed, suffering of it during real operation. Volumetric pumps can overcome this issue, having an efficiency ideally independent on rotational speed. In this work, triple-screw pump has been considered as a technological replacement for the centrifugal one, since it is a consolidated technology in other sectors, but never considered in engine cooling. Hence, a comprehensive zero-dimensional mathematical model of this pump has been proposed, improving the model developed by the authors in previous works and validating it through an extensive experimental campaign. Thus, a novel model-based methodology for the design of screw pumps for engine cooling applications has been proposed. After identifying a suitable design point for a screw-type engine cooling pump, the performance of a wide set of screw pump geometries has been studied, to identify the geometric proportions which maximize the pump efficiency. Moreover, the effects of the aspect ratio on triple screw pump performance have been investigated, optimizing the screw pump efficiency up to 60#x00025; for a typical engine cooling application. Finally, the so-designed pump has been applied on a small turbocharged gasoline engine, comparing it with a traditional existing centrifugal pump on a reference driving cycle. Results show a strong energy reduction (about 56#x00025;), which determines a significant reduction of CO2 emissions, equal to 2.08 g/km.