Air flows steadily between two sections in a long, straight portion of 10-cm inside diameter pipe. The uniformly distributed temperature and pressure at each section are given. The average air velocity at Sections (1) and (2) are 66 m/s and 300 m/s, respectively. Assume uniform velocity distributions. Determine the frictional force (Rx) exerted by the pipe wall on the airflow between the sections. At section (1), p1 = 7 MPa, T1 = 25°C, and V1 = 66 m/s. At section 2, p2 = 1.3 MPa, T1 = -20°C, and V2 = 300 m/s. (5 pt)

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?

During a steady flow process, the change of energy with respect to time is zero. a)- true b)- false

Air is compressed isentropically from an initial state of 300 k and 101 kpa to a final temperature of 1000 k. determine the final pressure using the following approaches: (a) approximate analysis (using properties at the average temperature) (b) exact analysis