Problem 1-1: Water in the bottom of a narrow metal cylinder is held at a constant temperature of 293 K. The total pressure of air (assued dry) is 1 atm and the temperature is 293 K. Water evaporates and diffuses through the air in the tube and the diffusion pathe is 0.15 m long. Calculate the rate of evaporation at steady state in kg mol/s m2. The diffusivity of water vapor at 293 K and 1 atm is 0.25 x 10-4 m2/s. Assume that the system is isthermal.
Problem 1-2: In problem 1-1, the water is 0.015 m deep, and the water level is 0.15 m from the top. As the diffusion proceeds, the level drops slowly. Calculate the time to evaporate all the water in the cylinder.
Problem 1-3: An insulated glass tube and condenser are mounted on a reboiler containing benzene and toluene. The condenser returens liquid reflux so that it runs down the wall of the tube. At one point in the tube, the temperature is 170 oF, the vapor contains 30 mol% toluene, and the liquid reflux contains 40 mol% toleune. The effective thickness of the stagnant vapor filem is estimated is to 0.1 inch. Assuming the molar latent heats of benzene and toluene are equal, calculate the rate at which toluene and benzene are being interchanged by equimolar counter current diffusion at this point in the tube. (Data: Dtoleuen,benzene = 0.2 ft2/hr, P=1atm, Pv,toluene at 170 oF = 400 torr.)
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안녕하세요,
물질전달 문제를 풀다가 궁금한 점이 있어서 이렇게 질문드리게 되었습니다.
먼저 1번과 2번은 등몰확산개념으로 접근해야 하는지,
아니면 한방향 확산개념으로 접근을 해야하는지 궁금합니다.
그리고 3번은 film이 stgnant한 상태이므로 상대적인 입장의 확산개념이고
벤젠과 톨루엔이 향류로 확산된다고 제시해 준것 같은데,
일반적인 단위조작책의 확산식에 적용하면 되는것인지 궁급합니다.
적용하는 것이라면 처음 방향을 어떻게 잡아야 할지 모르겠습니다.
감사합니다.
