CFD Numerical Simulation on Swirl-Flow Combustion in Freon Decomposition Burner

The Computational Fluid Dynamics (CFD) model of the freon decomposition burner with bicyclo-inlet is established by using Eddy-Dissipation Model (EDM) chemical reaction model. The jet-flow turbulent diffusion burning and swirl-flow combustion are simulated to prove that the swirl-flow combustion can get shorter blaze. The strong vortex flow enlarges the high temperature region in the burner and the temperature is more uniform, which is conducive to the freon decomposition at a great heat.

Combustion Characteristics of a Single-Cylinder Open-Chamber Diesel Engine

The combustion characteristics of an open-chamber diesel engine were examined by means of heat-release analysis and flame luminosity measurements. Increasing the load was found to decrease premixed burning and correspondingly to increase diffusion burning. During most of the diffusion combustion the burning rate of the fuel appeared to be directly proportional to the amount of unburned fuel present in the cylinder. The duration of heat release in crank-angle degrees increased linearly with load and, in general, increased with decreasing engine speed and retarded injection timing. The measured duration of flame luminosity was significantly longer than the calculated duration of heat release, which suggested that emission of radiation continued long after the heat-release reactions ceased.

On the Premixed Combustion in a Direct-Injection Diesel Engine

The factors influencing premixed burning and the importance of premixed burning on the exhaust emissions from a small high-speed direct-injection diesel engine were investigated. The characteristics of premixed and diffusion burning were examined using a single-zone heat-release analysis. The mass of fuel burned in premixed combustion was found to be linearly related to the product of engine speed and ignition-delay time and to be essentially independent of the total amount of fuel injected. Accordingly, the premixed-burned fraction increased with increasing engine speed, with decreasing fuel-air ratio and with retarding injection timing. The hydrocarbon emissions did not correlate well with the premixed-burned fraction. In contrast, the oxides of nitrogen emissions were found to increase with decreasing premixed-burned fraction, indicating that diffusion burning, and not premixed burning, is the primary source of oxides of nitrogen emissions.