1. Describe and explain the following briefly (1) To write down the define of the Reynolds number and describe the laminar flow and turbulent flow. (4\%) (2) To write down the define of hydraulic radius and equivalent diameter Dcq, and what is the hydraulic radius for annulus between two concentric pipes? (4\%) (3) Define the reflux and the used reason in the operation, what are the minimum reflux ratio and optimum reflux ratio? (4\%) (4) What is the effect of channeling? and to interpret the loading point and flooding point? (4\%) (5) Interpret the leaching and liquid extraction, and their application. (4\%) 2. A parabolic velocity profile of an incompressible fluid in a circular conduit, as figure. What is the average velocity (10%) and the sheer stress at the tube wall (10%) ? v=vmax[1(Rr)2] 3. The heat loss from a boiler is to be held at a maximum of 1000Btu/hrft2 of wall area. (1)What thickness of the asbestos (k=0.1Btu/hftF) is required if the inner and outer surfaces of the insulation are to be 1800F and 500F, respectively? ( 8%) If a 3 -in-thick layer of kaolin brick (k=0.07Btu/hftF) is added to the outside of asbestos, (2) what heat flux will result if the outside surface of the kaolin is 200F ? (6\%) (3) what will be the temperature at the interface between the asbestos and kaolin? (6\%) 4. A sphere of naphthalene having a radius of 5.0mm is suspended in a large volume of still air at 318K and 101.32kPa. The surface temperature of the naphthalene is 318K and its vapor pressure at 318K is 0.555mmHg. The DAB of naphthalene in air at 318K is 6.92106m2/s. (1) Calculate the rate of evaporation of naphthalene from the surface. (10\%) (2) Calculate the time in seconds for complete evaporation. The density of naphthalene is 1.14g/cm3 and molecular weight is 128.2g/mol)(10%) 5. A single-effect evaporator is concentrating a feed solution of organic solution from 10 to 60%. The boiling-point elevation of solution is negligible. The heat capacity of feed is Cp= 4.0kJ/kgK and the feed enter at 15.6C. Saturated steam (T=100C,s=2257.1kJ/kg) at 101.32kPa is available for heating, and the pressure of vapor space of the evaporator is 15.3 kPa(T=54.3C and Hv=2372.4kJ/kg). A total of 4500kg/h of water is to be evaporated. The overall heat transfer coefficient is 2000W/m2K. What is the required surface area in m2 (8%), the steam consumption (8%) and the steam economy (4%)