In addition, a gas turbine (KAWASAKI S2A-01) was applied as shown in Fig.2.

　

Fig. 2 Experimental Apparatus (Gas Turbine)

　

This system consists of one rotational shaft with a simple open-cycle gas turbine. It is the most simplified designed turbine that works with atmospheric air, and is needless to use a heat　exchanger. Variation of rotational speed owing to changing in loads is very slight because of the machine design is that the both of compression and operation are done by the same shaft. The compression of air is done by double-stages compressor. Its features are; higher compression ratio at each stage, simple machine design, performance decline due to blade's stain is less. The Combustion chamber needs stable combustion, high thermal efficiency, less in pressure decline and homogenous exhaust gas temperature. The test turbine is equipped with single closed vessel combustor that is designed for a kerosene fuel usage. This combustor is used to compare the difference in several fuels.

In this study, engines mentioned above were operated with the mixed fuel of diesel oil and rape-seed oil, also the alcohol fuel that is blended to the mixed fuel. Engine performance, and exhaust emissions were investigated and the effect of blending in alcohol was investigated and summarized. Fuels that were used in these experiments are shown in Table 1 and 2. ⁽²

　

Table 1. Comparison with Diesel Fuel Oil and Ethanol

Table 2 Mixing Conditions of Fuel

　

3. RESULTS

　

3.1 RESULTS FROM DIESEL ENGINE

Figure 3 shows the experimental results in the thermal efficiency of each mixed fuel. Here, it is shown that the thermal efficiency of the diesel fuel oil does not change largely from the efficiency of the diesel fuel / ethyl alcohol mixed fuel. Addition of alcohol to the base fuel (diesel fuel oil) does not affect to the efficiency declination.

Ethyl alcohol is half value in the caloric heat compared to the diesel fuel oil, and the latent heat of evaporation of ethyl alcohol is twice as large as the diesel fuel oil. Cetane number of alcohol is one seventh of the diesel fuel oil, thus it is not suitable for compression ignition engines. So, alcohol-fuel needs to be consumed larger amount of fuel to obtain the same level power with the diesel fuel oil. But from the aspect of thermal efficiency, it is available to use 20%(vol.) alcohol / 80%(vol.) diesel fuel blended fuel. It is obtained that in increasing with load the thermal efficiency becomes slightly lower with increase of blended alcohol amount. The reason is considered that the lower cetane number in alcohol causes unstable combustion.

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