Green coffee beans (rho=552 kg/m3, k = 0.184 W/m·K, c = 2.56 kJ/kg·K) are dried and roasted in a hot-air stream after harvesting. The hot air is typically at 250ºC, and the convection coefficient is 20 W/m2K. Beans are typically flat ellipsoids with average volume of 44 mm3 and average surface area of 66 mm2. For a flavorful and aromatic medium roast, the beans (initially at 22ºC) must be heated to 200ºC. Determine the required roasting time.

Aplate of dimensions 3 m x 3 m is placed 0.37 mm apart from a fixed plate. the plate requires a force of 2n to move at speed of 45 cm/s. evaluate the viscosity of the fluid in between the plates

An array of m-50 thermoelectric modules is installed on the exhaust of a sports car. each module has an effective seebeck coefficient of sp of 0.143 5vk and an internal electrical resistance of r.-4 ? in addition, : (15 points each module is of width w 60mm and contains n=100 pairs of semiconducting pellets. each pellet hasan overall length of 2l-5mm and a cross-sectional area as 1.2 x 10'm and is characterized by a thermal conductivity of kpl2w rnk. the hot side of each module is exposed to exhaust gases at·p650c with hia4ow rrk while the osite side of each module is cooled by pressurized water at surface) and 156 °c (at the cool surface). 11s c with h: -500w/m'k. the modules are wired n series and the load resistance is r d=400ohm .the module surface temperatures, t, and ts are 183 "c (at the hot surface and 156c (at the cool surface) a)-draw a schematic of this scenario and label all parts. a. b. if the induced current, i, is 0.15 amps, what is the total power (pa) for one module? c. what is the total power harvest from the exhaust with all 50 modules?

At what temperature does the mole fraction of no reach 0.010 for the equilibrium products resulting from the combustion of gasoline and air at 1.0 and 5000 kpa?