Tuesday, September 1, 2009

Sistem pembuatan lapisan fuel cell

....... The ultra-spray head with integrated fluid delivery system (IFDS) consists of an ultrasonic transducer with a spray forming tip, an ultrasonic generator, an external liquid applicator, a precision liquid delivery system and air directors. The ultrasonic transducer contains a spray-forming tip that vibrates at an ultrasonic frequency (> 20 kHz). The ultrasonic transducer is resonant at a particular ultrasonic frequency of 35 kHz, 45 kHz, or 60 kHz and is driven by an ultrasonic generator with a corresponding frequency. The particular ultrasonic frequency is selected based upon the material to be sprayed and the coating application requirements. In general, a lower frequency ultrasonic transducer is capable of spraying a higher viscosity liquid and producing higher flow rates. The amplitude of vibration of the spray-forming tip is also set with the ultrasonic generator. The amplitude is adjusted so that the particular coating material can be atomized for the required flow rate range. Some coatings require greater amplitude or more ultrasonic energy to properly atomize and some coatings require less. The ultrasonic frequency and amplitude are analogous to a loud speaker producing a single note. The frequency is the pitch of the note and the amplitude is the volume. An ultrasonic frequency of 35 kHz is optimal for most suspensions used in the manufacture of fuel cells. The amplitude of vibration of the spray-forming tip is then adjusted to accommodate the required flow rate range. The coating liquid is delivered to the spray-forming tip on the ultrasonic transducer with an external liquid applicator. The liquid is stored in a pressurized reservoir and fed to the liquid applicator with a precision liquid delivery system. The ultrasonic vibrations of the spray-forming tip break up the liquid into small drops and propel them from the tip in the form of a spray. The spray produced with ultrasonic energy alone is a very low velocity, narrow “sheet-like” pattern. The width of the spray pattern produced is equal to the width of the spray-forming
tip (2 mm to 4 mm). …continue.....


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