Argon oxy-hydrogen combustion for power generation employing linear joule cycle engine generator

Abstract

The global awareness of the unfavourable environmental effects due to fossil fuels' continuous use as the primary energy source has increased significantly. In order to tackle the adverse environmental consequences, innovative technologies will play a significant role. As a result, this thesis presents an investigation of the Linear Joule Engine Generator (LJEG) and its potential for zero-emissions power generation. It is believed that the results of the investigation will guide the further development of the LJEG. A background study on LJEG related technologies was conducted, focusing on the challenges and advantages of the reciprocating Joule Cycle engine and the free-piston engine generator. The semi-closed cycle argon-oxyhydrogen combustion LJEG was identified as the potential technology path towards LJEG development. This version of LJEG operated on dry friction principle, and an accurate friction model is required for a proper analysis of the engine. A novel friction model of the LJEG is proposed, and the proposed model validation was against test data from a lab-scale LJEG prototype. The dynamic and thermodynamic model of the LJEG was developed, and the numeric model validation was executed with the prototype's test data. The performance characteristics of the LJEG with different inputs and operating conditions were analysed. Results indicated that the friction model and the dynamic and thermodynamic model were reliable. The performance indicators of the LJEG depended on the input and operational parameters, and the most essential included the working fluid type, cycle pressure, valve timing, and electric load. The valve timing and electric load are optimised depending on preference between engine efficiency and power output. Operational parameter optimisation indicated that the efficiency decreased with extended expander intake duration but could improve with extended expander exhaust duration. Power output increased with longer expander intake duration; however, its relationship with compressor/expander diameter ratio (CER) depended on adopted expander exhaust duration. Substituting air with argon as the major working fluid resulted in over 60% improved indicated efficiency, and peak efficiencies of 40% and 60% are achieved with CER of 0.70 and 0.93, respectively. However, there could be a need for further fluid flow investigation; since the working volume of the expander and compressor is not fixed but could vary according to operation, and the fluid flow in the LJEG is pulsating.