EXPERIMENTAL STUDY ON A LOW TEMPERETATURE ORC UNIT FOR ONBOARD WASTE HEAT RECOVERY FROM MARINE DIESEL ENGINES

asme-orc2015 Tracking Number 55

The aim of this work is the experimental study of an ORC prototype unit which has been designed as a waste heat recovery system for the jacket water of marine diesel auxiliary internal combustion engines (ICEs). In order to simulate the operating characteristics of such engines, the heat input is in the order of 90kWth at low-temperature (90 oC) and is supplied by a natural gas boiler. The ORC unit produces 5 kWel of net electrical power, using as working medium the refrigerant R134a at a design cycle pressure of 25 bar and a temperature of 82 oC. The experimental evaluation of the unit focuses more on operational issues than overall performance which has already been experimentally studied by a number of researchers. Accordingly, this study includes the investigation of the behaviour of the whole ORC system as well as of its key components under varying operational parameters, such as the occurrence of cavitation in the system feed pump and optimal scroll expanders operation. These outcomes contribute to an optimized configuration of the ORC system components and of the necessary measuring equipment as well as to the development of an efficient automatic control strategy of a dedicated ORC test bench which could then be directly coupled to an adequately sized marine auxiliary ICE for real time operation assessment.