Construction of Heat Recovery Generation System for Co-generation in Commercial and Residential Sectors - Improvement of Scroll Shapes for High-power and High-performance in Scroll Steam Expander -

Abstract

This study is intended to develop the waste heat recovery generation system using steam-Rankine cycle for co-generation system with a small capacity prime mover in the range of about 500 kW or less. In our previous reports, a scroll expander has attracted attention as a power recovery device which has high efficiency potential even in the case of small power capacity, and the performance characteristics of it are investigated through the experiments. Then, it was confirmed that the leakage loss at the beginning of expansion process and the thermal loss cause the performance of the scroll expander to decrease. Therefore, in this paper, the shape of the orbiting scroll was redesigned to prevent the leakage, and also the type of the scroll expander was changed from symmetric scroll to asymmetric scroll which had high expansion ratio for high-power and high-performance. As a result, the expander performance was improved by the reduction of the leakage and the increase of the net power, and the expander efficiency reached up to 60.8 % at the maximum under the experimental conditions that the suction pressure of working fluid was 590 kPa and the revolution speed was 1950 rpm.