During the test, the measurement was made on the NOx concentration, etc. in the exhaust gas, the inspection of combustion products, etc. by overhauling the engine before starting and after completing the test, and various parts.
These results were considered, and the contents including the problems on the operational control for the practical application of the operation with the emulsified fuel are reported below.
3. Measurement of NOx in using emulsified fuel
After the emulsified fuel manufacturing device was installed in October, 1996, the operation using the emulsified fuel (hereinafter, referred to as the "measurement operation") was achieved to determine the running condition not to trouble the long-term operation of the diesel engine in the beginning, and to examine the influence on the concentration of NOx and CO in the exhaust gas and the ignition lag in the subsequent running condition.
The loads on the electric generator (the percentage with respect to the electric generator capacity of 400kW) were set to 25%, 50%, and 75%, and the water addition ratios to the respective loads (the volumetric ratio of water to be mixed to water of 100) were set to O%, 20%, 30% and 40%.
In general, the operation using the emulsified fuel with high water addition ratio has been regarded as an extremely effective NOx concentration reducing method except the low load area1). Also, in this test, the temperature of the exhaust gas was dropped by about 10-15(C during the operation using the emulsified fuel, and reduction of the NOx concentration was also confirmed as shown in Fig. 2. This figure also shows that, regarding the rise of the water addition ratio in the low load area of 30% or under, the NOx concentration is higher than the water addition ratio of O% except the water addition ratio of 40%, or rather in the rising trend. It is estimated that, in such a low load area, the ignition lag during the combustion by the emulsified fuel is more influential than the NOx reduction effect by the temperature drop of the combustion flame.
