Study of a low emission combustor - lean premix prevaporize concept

摘要

This thesis deals with the Lean Premix Prevaporize combustors for stirling and steam engines. The objective of this study has been to show that low-emission potential and the practical use of the combustor concept in these applications, and also to give some basic understanding of combustion generated emissions. Two combustors have been investigated and evaluated through experiments. The first prototype combustor used a dummy heater. The second combustor has been designed to fit a V160 stirling engine. For both combustors, carbon monoxide, unburned hydrocarbons and oxides of nitrogen have been measured. During these measurements combustor parameters such as thermal power, relative air/fuel ratio/exhaust gas recirculation/fuel flow and inlet temperatures have been varied in order to obtain a complete emission map. Two computer models have been used to predict emissions and temperatures. The first model predicts heat losses, temperature in the combustor and NO(sub x) emissions with a simple model. The other model used is Chemkin, which includes a one-dimensional laminar flame and full chemistry. The temperature profile from the first model is used as input to Chemkin. There is good agreement between measured emissions and emissions predicted with Chemkin. For the final version of the V160 combustor with an oxidizing catalyst, total emissions are less than 0.5 g/kWh (HC+NO(sub x)+CO) which is in the same range as an otto engine with a good three-way catalytic converter, or even better.