Question

Qi. A flat plate of width 1 m and length 0.2m is maintained at a temperature of 32°C. Ambient fluid at 22"C fBlows across the top of the plate in parallel flow. Determine the average heat transfer coefficient, the convection heat transfer rate from the top of the plate, and the drag force on the plate for the following: (a) The Buid is water flowing at a velocity of 0.5 m/s. o) Water is flowing at a velocity of 2.5 m/'s 02. Ar is to be cooled in the evaporaor secton ofarefriematar by rwing er abnk oftbes. Th tubes have an outer diameter of O X em and length of 0.4 m. The nefirgerant is evaperating inside t tubes at-20C Air approars-the the bank in the normal drnem arrcnd lat velocity of 4 m/s. The tube are arrangad staggened with longtdigal and tonsverse pitches of S Sr-15 am. There are 30 rows in the flow direction with 15 tobies in cach ww.Assume the tube temperature to be fixed at-20 ℃. a. Draw the tube bank arrangement and show the longitadinal and transverse pitches Determine the convection heat transfor cocfficient e. Determine the air temperature when it exits the tubes bank d. Determine the logarithmic mean semperature difference. Determine the rate of heat transfer E. Read the properties of air at an assumed mean temperature, Tm-5 Done Expert Q&A 03 A thin-walled tube with a dameter of 6 mm and iength of 20m s used to carry axhaust ga from a smoke stack to the labortory in a nearby building for analyss. The gas enters the ube at 200 C and with a mass flow mte dl 0.003 kg/s. Autumn winds at a temperature of 15 C blow direcly across the tube at a velocity of 5 m's Assume the therme physical propeties of the exugs are those of ar while the outside air properties is: hea transler

Answer 1

(e21. water 2. Reynold, Nomber, at the end 업<the-afe : ReL ev 10 トtale :Cy -O.5 3 3.83 x1o = 0.2m2. 2,

X S. 85 Ami 2524.4 Wna 32 -22 3.568 x o r ea רו42

3 2、216 X 10 2 945 k 2.5) Drag ce FD 66.2 m214