5) Two concentric spheres of diameter D1= 70 cm and D2= 120 cm are separated by an air space and have surface temperatures of T1= 117 C and T2= 27 C. (a) If the surfaces are black, what is the net rate of radiation exchange between the spheres, in W? (b) What is the net rate of radiation exchange between the surfaces if they are diffuse and gray with ε1= 0.5 and ε2= 0.05, in W? (c) What is the net rate of radiation exchange if D2 is increased to 2000 cm, with ε2= 0.05, ε1= 0.5, and D1= 70 cm, in W? (d) What is the net rate of radiation exchange if the larger sphere behaves as a black body (ε2= 1.0) and with ε1= 0.5, D2= 2000 cm, and D1= 70 cm, in W?

Amass of m 1.5 kg of steam is contained in a closed rigid container. initially the pressure and temperature of the steam are: p 1.5 mpa and t 240°c (superheated state), respectively. then the temperature drops to t2= 100°c as the result of heat transfer to the surroundings. determine: a) quality of the steam at the end of the process, b) heat transfer with the surroundings. for: p1.5 mpa and t 240°c: enthalpy of superheated vapour is 2900 kj/kg, specific volume of superheated vapour is 0. 1483 m/kg, while for t 100°c: enthalpy of saturated liquid water is 419kj/kg, specific volume of saturated liquid water is 0.001043m/kg, enthalpy of saturated vapour is 2676 kj/kg, specific volume of saturated vapour is 1.672 m/kg and pressure is 0.1 mpa.

Two technicians are discussing the intake air temperature (iat) sensor. technician a says that the computer uses the iat sensor as a backup to the engine coolant temperature (ect) sensor. technician b says that the powertrain control module (pcm) will subtract the calculated amount of fuel if the air measures hot. who is correct

An ideal otto cycle with air as the working fluid has a compression ratio of 8. the minimum and maximum temperatures in the cycle are 300 k and 1340 k. use constant specific heats at room temperature to determine (a) the amount of heat transferred to the air during the heat- addition kj/kg, (b) the thermal efficiency, and (c) the thermal efficiency of a carnot cycle ope limits. process, in rating between the same temperature