For the same initial conditions one can expect the laminar t

For the same initial conditions, one can expect the laminar thermal and momentum boundary layers on a flat plate to have the same thickness when the prandti number of the flowing fluid is Close to zero Small Approximately one very large A square distribution duct has the dimension of 20cm X 40cm. At partial load condition, the duct is only half filled(see the diagram below). What is the characteristic length when an eneineer tries to calculate the convective heat loss through the duct? 40cm 20cm 26.7cm 28.3cm Engineers take some filed measurements to estimate the convective heat transfer coefficient between hot water and the steel pipe that carries the hot water. Measurements show that the inlet mean temperature is 60degreeC and the exit mean temperature is 50degreeC. The pipe is subjected to a constant surface temperature of 40degreeC. Which temperature would you use in looking up water properties in the associated convective heat transfer analysis? 55degreeC 45degreeC 50degreeC 60degreeC A mechanical engineer needs to measure mass air flow of all main ducts in a hotel in order to determine whether its forced air system is balanced or not. An AirMeter takes that the velocity at the center of a circular duct of 5cm radius is 8m/s. What is the volume air flow rate in this duct m m^3/s? Assume that the measurement is taken in a location within the fully developed region. 0.03 0.06 314 628

Solution

5) C( prandtl number=1)

8)volumetric flow rate=areax velocity

Ans ) 0.06

6) B

7)A((inlet+ outlet)/2)