Q1 a) What is the physical significance of Reynolds number? Write down 5 (five) factors that influence the convection heat transfer rates. b) Water is to be heated from 10°C to 80°C as it flows through a 2-cm-internal-diameter, 7-m- long tube. The tube is equipped with an electric resistance heater, which provides uniform heating throughout the surface of the tube. The outer surface of the heater is well insulated, so that in steady operation all the heat from the heater is transferred to the water in the tube. If the system is to provide hot water at a rate of 8 L/min, determine the convection heat transfer coefficient and temperature at the inner surface of the pipe at the exit. Q2 a) Consider heat transfer to oil flow inside a copper pipe. Is the pipe length affecting the heat transfer rate into the oil? Briefly explain. b) Used engine oil can be recycled by a patented reprocessing system. Suppose that such a system includes a process during which engine oil flows through a…

Water enters a 5-mm-diameter and 13-m-long tube at 15ºC with a velocity of 0.3 m/s, and leaves at 45ºC. The tube is subjected to a uniform heat flux of 2000 W/m2 on its surface. The temperature of the tube surface at the exit is(a) 48.7ºC (b) 49.4ºC (c) 51.1ºC (d) 53.7ºC (e) 55.2ºC(For water, use k = 0.615 W/m⋅°C, Pr = 5.42, ν =0.801×10-6 m2/s)

heat transfer

Combustion gases passing through a 3-cminternal- diameter circular tube are used to vaporize waste water at atmospheric pressure. Hot gases enter the tube at 115 kPa and 250°C at a mean velocity of 5 m/s, and leave at 150°C. If the average heat transfer coefficient is 120 W/m2?K and the inner surface temperature of the tube is 110°C, determine (a) the tube length and (b) the rate of evaporation of water.

Heat Transfer Question is image part ii) ?

Write your answer in 4 decimal places. DO NOT round off intermediate values. Water (Cp = 4180 J/kg-K) enters a 4-cm-diameter tube at 15°C at a rate of 0.06 kg/s. The tube is subjected to a uniform heat flux of 2500 W/m2 on the surfaces. The length of the tube required in order to heat the water to 45°C is m

Heat Transfer Question is image part iii) ?

The boiling temperature of oxygen at atmospheric pressure at sea level (1 atm) is -183ºC. Therefore, oxygen is used in low temperature scientific studies since the temperature of liquid oxygen in a tank open to the atmosphere remains constant at -183ºC until the liquid oxygen in the tank is depleted. Any heat transfer to the tank results in the evaporation of some liquid oxygen, which has a heat of vaporization of 213 kJ/kg and a density of 1140 kg/m3at 1 atm. Consider a 4 m diameter spherical tank initially filled with liquid oxygen at 1 atm and -183ºC. The tank is exosed to 20ºC ambient ait with a heat transfer coefficient of 25 W/m2. ºC. The temperature of the thin-shelled spherical tank is observed to be almost the same as the temperature of the oxygen inside. Disregarding any radiation heat exchange, determine the rate of evaporation of the liquid oxygen in the tank as a result of the heat transfer from the ambient air

Heat Transfer Lesson The temperature will be increased from 10 (Degree Celsius oC) to 90 (Degree Celsius oC) while the water flows through a 1.5 cm inner diameter and 7 meter long straight pipe. Equipped with electric heater on the entire surface of the pipe. Even heating throughout. The outer surface of the heater is well insulated and therefore all heat generated in the heater in continuous operation is transferred to the water in the pipe. If the system provides a hot water flow rate of 6 liters / minute. (Thermophysical properties of water at 50 oC:ρ = 988 m3/kg, k= 0.6305 W/m oC, cp=4181 J/kg oC, Pr=3.628, μ= 0.0005471 kg/m.s ) a)Find the power of the resistance heater [W]. b)Calculate the inner surface temperature [oC] of the pipe at the outlet. c)Find the pressure drop [Pa]. d)Find the pump power [W] required to overcome this pressure drop.