Two long concentric cylinders exchange heat by radiation. The inner cylinder having a diameter of 10 cm has T1 = 1000 K and ε1=0.65 while the outer cylinder having a diameter of 20 cm has T2 = 500 K and ε2=0.40. Calculate the net heat transfer between the two cylinders per unit length

The temperature of air decreases as it is compressed by an adiabatic compressor. a)- true b)- false

Refrigerant 134a enters an insulated compressor operating at steady state as saturated vapor at -26°c with a volumetric flow rate of 0.18 m3/s. refrigerant exits at 9 bar, 70°c. changes in kinetic and potential energy from inlet to exit can be ignored. determine the volumetric flow rate at the exit, in m3/s, and the compressor power, in kw.

Ariver flows from north to south at 8 km/h. a boat is to cross this river from west to east at a speed of 20 km/h (speed of the boat with respect to the earth/ground). at what angle (in degrees) must the boat be pointed upstream such that it will proceed directly across the river (hint: find the speed of the boat with respect to water/river)? a 288 b. 21.8 c. 326 d. 30.2