The benefits introduced by the replacement of conventional centrifugal pumps with volumetric machines for Internal Combustion Engines (ICEs) cooling were experimentally and theoretically proven in literature. Sliding Rotary Vane Pumps (SVRPs) ensure to achieve an interesting reduction of ICEs fuel consumption and CO2 emissions. Despite volumetric pumps are a reference technology for ICE lubrication oil circuits, the application in ICE cooling systems still not represent a ready-to-market solution. Particularly challenging is the case of Heavy-Duty ICEs due to the wide operating range the pump covers in terms of flow rate delivered and pressure rise.
Generally, SVRPs are designed to operate at high speeds to reduce machine dimensions and, consequently, the weight. Nevertheless, speed increase could lead to a severe penalization of pump performance since the growth of the friction losses. They produce wear phenomena which require expensive surface treatments or, more generally, the adoption of materials which resist to higher mechanical stresses. Authors in their previous works developed an alternative design strategy based on the speed reduction compensating the size growth with an increase of the volumetric capability. It was found thanks to a peculiar property of SVRPs. An optimized variation of machine eccentricity leads to a higher volume capability, with a negligible increase of machine dimensions. In this way, the operating speed could be reduced avoiding the increase of machine size. A Low-Speed (LS) SVRP prototype was hence built, and the benefit introduced by the proposed design strategy was experimentally demonstrated in previous works after a theoretical model-based design.
A further increase of performances was presented in this paper. Machine shaping was indeed optimized in terms of stator diameter/pump length ratio, considering that the two geometrical parameters influence volumetric, indicated, and mechanical efficiencies. The optimization of these performances produces a combined positive effect on the pump overall efficiency improvement. Hence, thanks to an updated more comprehensive modelling, an optimized model-based design was produced in this work. Finally, the optimized SVRP was compared with the conventional centrifugal pump operating on the reference ICE (CURSOR 13 NG) over a WHTC (World Harmonized Transient Cycle) and the benefits offered in terms of energy reduction to drive the pump was calculated.