The physicochemical properties of fuels and engine performance parameters have a significant impact on emissions. This study focuses on modeling the influence of fuel properties and engine parameters on CO₂, CO, NOₓ, and PM emissions, with particular attention to particulate matter emission indices and particle size distribution parameters, such as geometric mean diameter and geometric standard deviation. The models were developed based on experiments conducted on a miniature jet engine (GTM 400) fueled with HEFA-SPK blends in various proportions. Multi-linear regression with data standardization was used for model development. The models identified which parameters have the greatest impact on specific emission indices and how variations in input parameters affect emission outcomes. Eighteen fuel properties and engine performance parameters were included in the model development, and all eleven resulting models showed good agreement with measured data and were validated using separate test points. This research addresses a gap in the literature by modeling the impact of HEFA-SPK fuel properties on pollutant emissions in miniature jet engines, with an added focus on particle size distribution parameters. By evaluating alternative fuels such as HEFA-SPK and their effect on emission characteristics, this study contributes to advancing sustainability in aviation propulsion systems.