Investigating high temperature solid lubricant material for a scroll expander

In the context of a waste heat recovery application on a gasoline engine, tribological investigations have been mandatory in the design of a scroll expander. A new design has been proposed to reach higher temperature and investigations are made to ensure that the material of the parts in contact will provide good tribological performances, i.e. a low coefficient of friction and a low wear rate. This research will also prevent high mechanical losses in the machine and, therefore, increase its thermal efficiency. Some experiments have been conducted on six different materials for the tip seal of the expander and two materials for the counter face. Additionally, the experiments have been carried out for a dry and a steam-lubricated contact at several temperatures. This research does not aim to be an exhaustive tribological investigation but instead offers a first comparison between the different materials couples.

Study on Effects of Inlet Resistance on the Efficiency of Scroll Expander in Micro-Compressed Air Energy Storage System

As an important part of a micro-compressed air energy storage system, the scroll expander directly affects the efficiency of the whole energy storage system. The effects of resistance on the efficiency of scroll expander caused by inlet structure and size are discussed with theory analysis and experimental methods in this paper. Micro-compressed air energy storage system has aroused widespread attention because of its pollution-free, high flexibility, in the community, remote areas power supply. Comprehensive experimental work with the selections of different size and structure of the air inlet of the scroll expander was performed with the cutting angle of air inlet chamber of the scroll expander. The results of the experiments are discussed on how exergy efficiency and inlet flow of the scroll expander were affected resulting from the cutting angles dissected. The results show that a maximum value exists for exergy efficiency of the scroll expander. Therefore, the exergy efficiency of the scroll expander can be effectively improved by enlarging the air inlet port dimension and modifying the size of air chamber.