Effects of Fuels' Heating Value and Air to Liquid Mass Ratio on Twin Fluid Atomizer Spray Combustion

摘要

In twin fluid atomization, increasing Air to Liquid Ratio (ALR) by mass is known to produce spray with smaller droplets. In liquid fuel combustion systems, smaller droplets are desirable to improve fuel evaporation, fuel-air mixing, and combustion efficiency. However, ALR cannot be increased infinitely because of the combustion static stability concerns limiting the maximum possible ALR. In particular, Lower Heating Value (LHV) of the fuel is an important property affecting static flame stability. In this study, effect of LHV on maximum limit of ALR was investigated by conducting combustion experiments in a swirl stabilized dual fuel burner utilizing Flow-Burring (FB) injector operated on diesel, vegetable oil (VO) and glycerol fuels. Visible and infrared images of the three fuels at different ALR showed that with glycerol, which has the lowest LHV of the three fuels, significant flame stability issues were noticed as ALR is increased to above 2.1. On the other hand diesel and straight VO flames were stable for ARL of up to 3.1. Theoretical analysis with consideration of atomizing air flow rate, ALR, and fuel residence time are presented to support these experimental findings.