1. Mass Transfer (50 points) In designing a fuel cell system for a car, an engineer...

 

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1. Mass Transfer (50 points) In designing a fuel cell system for a car, an engineer has proposed using an A106 Grade B carbon steel tube to transfer Hydrogen from the generator to the fuel cell. The average operating temperature of this system is expected to be about 150C. The tube itself is to be 1 meter in length and 2 cm in diameter with a thickness of 3 mm. Based on the production from the generator, the concentration of Hydrogen at the inner surface of the tube is estimated to be 2.5x10' kmol H2/m. What is the molar flowrate (in kmol H/s) through the tube wall under steady state conditions? For the purposes of this problem, one can consider the Hydrogen content of the atmosphere negligible. Savannah River National Laboratory has performed a number of experiments on the diffusion of Hydrogen through various grades of carbon steel and has found that for A106 Grade B carbon steel the Diffusion Coefficient is 1.34x1011 m2/s at 150C. Based on the description of the system, what is the mechanism of diffusion for the hydrogen in this problem? Make sure to briefly justify your response. (Hint: Make sure you read the problem carefully and identify the direction of mass transfer so you can correctly determine the correct cross-sectional area to use.) 1. Mass Transfer (50 points) In designing a fuel cell system for a car, an engineer has proposed using an A106 Grade B carbon steel tube to transfer Hydrogen from the generator to the fuel cell. The average operating temperature of this system is expected to be about 150C. The tube itself is to be 1 meter in length and 2 cm in diameter with a thickness of 3 mm. Based on the production from the generator, the concentration of Hydrogen at the inner surface of the tube is estimated to be 2.5x10' kmol H2/m. What is the molar flowrate (in kmol H/s) through the tube wall under steady state conditions? For the purposes of this problem, one can consider the Hydrogen content of the atmosphere negligible. Savannah River National Laboratory has performed a number of experiments on the diffusion of Hydrogen through various grades of carbon steel and has found that for A106 Grade B carbon steel the Diffusion Coefficient is 1.34x1011 m2/s at 150C. Based on the description of the system, what is the mechanism of diffusion for the hydrogen in this problem? Make sure to briefly justify your response. (Hint: Make sure you read the problem carefully and identify the direction of mass transfer so you can correctly determine the correct cross-sectional area to use.)