Question 51. For transient flow, the value of Reynolds number may vary between

Question 52. A hot plate of 15 cm² area maintained at 200 degree celsius is exposed to still air at 30 degree Celsius temperature. When the smaller side of the plate is held vertical, convective heat transfer rate is 15 per cent higher than bigger side of the plate is held vertical. Find size of the plate. The appropriate correlation for the convection coefficient is
Nu = 0.60 (Gr Pr)^0.25

Question 53. Conduction plus fluid flow in motion is known as

Question 54. Mark the system where heat transfer is given by forced convection

Question 55. Which of the following heat flow situations pertains to free or natural convection?

Question 56. How many types of convection are there?

Question 57. Forced convection in a liquid bath is caused by

Question 58. For laminar flow, Prandtl number must be more than

Question 59. Air at atmospheric pressure and 20 degree Celsius flows with 6 m/s velocity through main trunck duct of air conditioning system. The duct is rectangular in cross-section and measures 40 cm by 80 cm. Determine heat loss per meter length of duct corresponding to unit temperature difference. The relevant thermos-physical properties of air are
v = 15 * 10¯⁶ m²/s
α = 7.7 * 10¯² m²/hr
k = 0.026 W/m degree

Question 60. For a plate of length l, an average value of Nusselt number is given by