Experimental measurements of the convection heat transfer coefficient for a square bar in cross flow yielded the following values: h1=50 W/m^2⋅K when V1=20 m/s
h2=40 W/m^2⋅K when V2=15 m/s

Assume that the functional form of the Nusselt number is
¯¯¯¯¯¯¯¯
Nu= C Re^mPr^n
where C, m, and n are constants.

a. What will be the convection heat transfer coefficient for a similar bar with L = 1 m when V = 15 m/s?
b. What will be the convection heat transfer coefficient for a similar bar with L = 1 m when V = 30 m/s?
c. Would your results be the same if the side of the bar, rather than its diagonal, were used as the characteristic length?

An electrical motor raises a 50kg load at a construct velencity .calculate the power of the motor, if it takes 40sec to raise the load through a height of 24m(take g =9.8n/g)

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?

Asimple rankine cycle uses water as the working fluid. the water enters the turbine at 10 mpa and 480c while the condenser operates at 6 kpa. if the turbine has an isentropic efficiency of 80 percent while the pump has an isentropic efficiency of 70 percent determine the thermal efficiency