| Budget Amount *help |
¥2,550,000 (Direct Cost: ¥2,400,000、Indirect Cost: ¥150,000)
Fiscal Year 2007: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2006: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2005: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2004: ¥900,000 (Direct Cost: ¥900,000)
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| Research Abstract |
Three types of high frequency inverters were prepared to generate super-steam, which operate at 100, 200 and 300 kHz, respectively. The circuit constitution adopted was the voltage-fed full bridge type operated at zero current switching operation (ZCS).
Switching devices utilized were Static Induction Transistors (SITs) for the 100 and 200 kHz inverters and power MOS FET for the 300 kHz inverter, respectively. The inverters were designed at maximum input power of 6.4 kW (400V/16A). The prepared breadboards were operated at input voltage of 200 V. The load for super-steam generation was the pipe made of Teflon resin (outer diameter of 120 mm, inner diameter of 100 mm and length of 400 mm), which contained a heating substance. It came from the reason that Teflon resin was easy to process. At first, carbon ceramics and magnetic stainless steel were adopted as the heating substance. However, our preliminary experiment revealed that carbon ceramics was found suitable for the heating substanc
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e due to its stability as the heating load. The carbon ceramics was a cylinder of 90 mm in diameter and 90 mm in height. The 14 holes of 10 mm in diameter were bored in it to increase its contact surfaces with a fluid flowing through it. Three carbon ceramics were inserted into the Teflon pipe in vertical direction with 15 mm gaps. Super-steam was known active above 170 ℃, however, its maximum temperature was restricted below 260 ℃ in our experiments. It took into account the fact that the heat-resistive temperature of Teflon resin was 300 ℃.
The high frequency inverters of 100 and 200 kHz using SITs could be operated stably in spite of some distortion in their waveforms. On the other hand, the inverter of 300 kHz using power MOSFETs revealed substantial distortion in its waveforms. Accordingly, its circuit constitution and driving circuits should be refined. In our experiments, water of 800 cc was inserted into the Teflon pipe so that whole of the bottom carbon ceramics was submerged in water. Then, the water was heated till 98 ℃. Finally, heating process was continued till the temperature of the other two carbon ceramics reached 260 ℃. As a result, transparent super-steam was detected to generate. In addition, simulation analysis revealed the definite design procedure for high frequency inverters of 100, 200 and 300 kHz of super-steam generation feeding output power of 50 kW on the basis of our experimental results.
Moreover, operational principle and experimental results of an SEPP resonant high frequency inverter with auxiliary switches operating at high efficiency were found useful for induction heating uses. However, super-steam could not be generated by it since its output power was insufficient. Less
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