Question 21. For inclined plates we multiply Grashoff number with

Question 22. The free convection coefficient is given by
h = C₁ d t m/l^(1 – 3m)
The value of exponent for turbulent flow is

Question 23. For laminar flow, Reynolds number must not be less than

Question 24. A horizontal heated plate at 200 degree Celsius and facing upwards has been placed in still air at 20 degree Celsius. If the plate measures 1.25 m by 1 m, make calculations for the heat loss by natural convection. The convective film coefficient for free convection is given by the following empirical relation
h = 0.32 (α)^0.25 W/m² K
Where α is the mean film temperature in degrees kelvin

Question 25. Which of the following is true for laminar flow?

Question 26. A finned tube hot water radiator with a fan blowing air over it is kept in rooms during winter. The major portion of the heat transfer from the radiation is due to

Question 27. A body cooling from 80 degree Celsius to 70 degree Celsius takes 10 minutes when left exposed to environmental conditions. If the body is to cool further from 70 degree Celsius to 60 degree Celsius under the same external conditions, it will take

Question 28. A sphere, a cube and a thin circular plate, all made of the same material and having the same mass are initially heated to the temperature of 250 degree Celsius. When left in air at room temperature, what will be their response to cooling?

Question 29. On a summer day, a scooter rider feels more comfortable while on the move than while at a stop light because

Question 30. What is the value of convective coefficient of oil in case of forced convection?