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Engine experiments have been conducted on a gas fueled SI engine. The engine was fueled with natural gas and mixtures of natural gas and hydrogen containing producer gas in order to examine the effect of addition of producer gas on the combustion process and the engine-out emissions. The experiments showed that addition of producer gas decreased the UHC emission at conditions leaner than λ=1.40. The CO emission was increased by addition of producer gas. This was mainly caused by unburned fuel CO from the producer gas. No effect of producer gas on the NOx emission was detected. Formaldehyde, which is suspected to cause odor problems from natural gas fired engine based power plants, was measured using FTIR. The investigation showed that the formaldehyde emission was decreased significantly by addition of producer gas to natural gas.

Engine experiments with a 0.964 l. DI diesel engine have been carried out applying mixtures of diesel and bitumen as fuel. These investigations showed that there is an increase in emissions of CO, NOx, PM1 and SOF2 as the share of bitumen in the fuel increases. Sampled PM from the exhaust gas from a 0.296 ltr. DI diesel engine was analysed for its contents of 16 specific PAH-compounds. The results showed that the emission of PAH in the exhaust gas was significantly lower for mixtures of bitumen/diesel than for mixtures of heavy-fuel-oil/diesel. Seven different components where detected. Analysis of soot deposits from the combustion chamber and of the crank case lubricant concerning magnesium, vanadium and nickel have been carried out. The results showed that 2-5% of the amount of metals in the injected fuel could be found in the engine lubricant. Only a small amount of magnesium and vanadium was detected in the soot.

Experimental investigations with a combustion bomb have been carried out with mixtures of methane and producer gas produced by thermal gasification of biomass. The investigations showed that the lamin ar flame speed increased and the amount of UHC decreased for increasing amount of producer gas in the fuel. Application of mathematical models for calculations of quench distances near the bomb walls and post oxidation reactions has led to the conclusion that the amount of unburned fuel is reduced primarily due to a promotion of post oxidation processes. Engine experiments have been carried out applying mixtures of natural gas and gasification gas as fuel for different air-fuel ratios. These investigation showed that substituting 16% (Vol.) of the natural gas by producer gas resulted in a decrease of 50% (Vol.) of the UHC from the combustion for lean mixtures.