This study forms part of an ongoing program to investigate the feasibility of substituting a bio-oil for gas-oil in gas turbine applications. In this paper, the influence of the change of fluid properties on spray characteristics is presented and analyzed. It was not feasible to characterize the spray at full-scale operating conditions, and so a scaling methodology was adopted using published correlations. The study was conducted in three stages; a scaled nozzle was selected utilizing a published correlation to ensure the spray characteristics match the critical characteristics of the full-scale nozzle. The scaled nozzle was then characterized with a gas-oil as a benchmark for comparison with the bio-oil tests. Finally bio-oil tests were conducted at elevated fuel preheat temperatures and the spray characteristics compared to the benchmark case. The objective of the program was to provide an insight into the effect of fuel preheat on spray characteristics. The results of this program helped determine scaled operating conditions for a subsequent atmospheric combustion program, not presented in this paper. The spray characterization was conducted in the atmospheric spray rig (ASR) located at Cardiff University’s GTRC, at Port Talbot, UK. The experiments presented were conducted using bio-oil at elevated fuel preheat temperatures. The spray structure and mean droplet sizes are measured for a bio-oil at various initial pre-heat temperatures and compared with the benchmark gas-oil case. Operating conditions were chosen to maintain an equivalent thermal load of approximately 1.5 MW. Good quality PDA data were recorded for all cases and demonstrated that primary spray characteristics for bio-oil could be optimized and matched to those of gas-oil utilizing the same fuel delivery system. This was achieved by implementing a fuel pre-heat of 80 °C, thereby changing the delivery conditions of the bio-oil.

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