Refrigerant 134a enters the evaporator of a refrigeration system operating at steady state at -4oC and quality of 20% at a velocity of 7 m/s. At the exit, the refrigerant is a saturated vapor at a temperature of -4oC. The evaporator flor channel has constant diameter. If the mass flow rate of the entering refrigerant is 0.1 kg/s, determine (a) the diameter of the evaporator flow channel (in cm). (b) the velocity at the exit (in m/s).

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?