A converging-diverging nozzle with a rectangular cross-section and exit area ratio AAee⁄AAtt = 4.0 operates in an under-expanded condition. The working gas is air, the back pressure away from the nozzle exit is ppaa = 10 kPa, and the stagnation pressure is pp0 = 500 kPa. The exit pressure is greater than the back pressure (ppee > ppaa), so expansion waves form outside the exit. For the given conditions, what is the Mach number on the downstream side of the first set of expansion waves, and what is the turning angle?

Line joining liquid phase with liquid and solid phase mixture is known as: a) liquidus b) solidus c) tie line d) none of the mentioned

Air is to be cooled in the evaporator section of a refrigerator by passing it over a bank of 0.8-cm-outer-diameter and 0.4-m-long tubes inside which the refrigerant is evaporating at -20°c. air approaches the tube bank in the normal direction at 0°c and 1 atm with a mean velocity of 4 m/s. the tubes are arranged in-line with longitudinal and transverse pitches of sl- st 1.5 cm. there are 30 rows in the flow direction with 15 tubes in each row. determine (a) the refrigeration capacity of this system and (b) pressure drop across the tube bank. evaluate the air properties at an assumed mean temperature of -5°c and 1 atm. is this a good assumption?

Water at 55c flows across a flat plate whose surface temperature is held constant at 95c. if the temperature gradient at the plate's surface for a given value of x is 18 c/mm, find a) local heat transfer coefficient. b) heat flux