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.

Apipe with an outside diameter of 15 cm is exposed to an ambient air and surrounding temperature of -20°c. the pipe has an outer surface temperature of 65°c and an emissivity of 0.85. if the rate of heat loss from the pipe surface is 0.95 kw per meter of length, the external convective heat transfer coefficient (h) is: (a) 12.5 w/m"k (b) 18.6 w/mk (c) 23.7 w/mk (d) 27.9 w/mk (e) 33.5 w/mk

Consider a large isothermal enclosure that is maintained at a uniform temperature of 2000 k. calculate the emissive power of the radiation that emerges from a small aperture on the enclosure surface. what is the wavelength ? , below which 10% of the emission is concentrated? what is the wavelength ? 2 above which 10% of the emission is concentrated? determine the wavelength at which maximum spectral emissive power occurs. what is the irradiation incident on a small object placed inside the enclosure?

Calculate the bore of a cylinder that has a stroke of 18 inches and an extension time of 6 seconds at a flow rate of 4 gal/min.