Question 31. In heat dissipation from an infinitely long fin, the boundary conditions are

Question 32. Let us say there are two rods having same dimensions, one made of brass (k = 85W/m K) and the other of copper (k = 375W/m K), having one of their ends inserted into a furnace. At a section 10.5 cm away from the furnace, the temperature of brass rod is 120 degree Celsius. Find the distance at which the same temperature would be reached in the copper rod? Both ends are exposed to the same environment

Question 33. The temperature distribution in case of infinitely long fin is

Question 34. The rate of heat transfer in case of infinitely long fin is given by

Question 35. Three rods, one made of silver (l = 420W/m K), second made of aluminum (k = 210W/m K) and the third made of iron (k = 70W/m K) are coated with a uniform layer of wax all around. The rods are placed vertically in a boiling water bath with 250 mm length of each rod projecting outside. If all the rods are having following dimensions i.e. diameter = 15 mm and length = 300 mm and have identical surface coefficient 12.5W/ m² K, work out the ratio of lengths up to which wax will melt on each rod

Question 36. A rod of 10 mm square section and 160 mm length with thermal conductivity of 50W/m K protrudes from a furnace wall at 200 degree Celsius with convective coefficient 20 W/ square m K. Make calculations for the heat convective up to 80 mm length

Question 37. A fin protrudes from a surface which is held at a temperature higher than that of its environment. The heat transferred away from the fin is

Question 38. The parameter m = (h P/k A C)^1/2 has been stated to increase in a long fin. If all other parameters are constant, then

Question 39. The value of correction length for equilateral fin is

Question 40. The relevant boundary conditions in case of heat dissipation from a fin insulated at the tip are