The Model and Burner Development for Crude Glycerol and Used Vegetable Mixing: Cube Mushroom Steaming Oven

Reduce fuel costs, improve waste utilization, and enhance energy efficiency by steaming mushroom substrate cubes using a mixed-fuel burner and furnace system that uses crude glycerol and used vegetable oil as alternative low-cost energy sources. This was the objective of this study. The experimental method measured boiler performance, exhaust-gas composition, temperature profiles, steam generation, and combustion-gas distribution inside the furnace. It was supported by analytical modeling of pressure, temperature, and combustion-gas distribution. Five fuel mixtures were prepared and tested, including 100% used vegetable oil, 100% glycerol, and 50/50, 25/75, and 10/90 blends. The tests were conducted in accordance with DIN EN 203-1. Blending used vegetable oil with glycerol improves flame stability, increases peak temperatures, and reduces the formation of incomplete combustion products compared to pure glycerol. The results also show that the mixture achieves high combustion efficiency (≈90-99%) and boiler thermal efficiency (≈72-73%). The optimal blend for stability, efficiency, and cost savings was 25/75 glycerol and vegetable oil. By cutting yearly fuel expenses by almost half, reducing steaming time by 2 hours per batch, and achieving a quicker payback period (3.26 months), the mixed-fuel system proved to be economically more advantageous than LPG, making it evidently practicable for agricultural producers. This study's conclusions suggest that, to maximize the use of renewable waste fuels and improve long-term sustainability, the following actions should be taken: further optimizing the air-fuel mixing process to improve combustion of higher-glycerol blends; scaling the system for larger mushroom farms; and expanding testing to other agricultural heating applications.