20.1-6. drying of wood. a flat slab of douglas fir wood 50.8 mm thick and containing 30 wt % moisture is being dried from both sides (neglecting ends and edges). the equilibrium moisture content at the surface of the wood due to the drying air blown over it is held at 5 wt % moisture. the drying can be assumed to be represented by a diffusivity of 3.72 × 10 –6 m2 /h. calculate the time for the center to reach 10% moisture.

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?

Apreheater involves the use of condensing steam at 100°c on the inside of a bank of tubes to heat air that enters at 1 atm and 25°c. the air moves at 5 m/s in cross flow over the tubes. each tube is 1 m long and has an outside diameter of 10 mm. what is the minimum value of nl needed to achieve an outlet temperature of t 75 c? what is the corresponding pressure drop across the tube bank?

List and describe the parts of boxford cnc milling machine with pictures?