Hot water (specific heat of 4.18 Kj/kgK) at 66C is flowing through a metal pipe (6 m long, 2 cm ID, 2.75 OD, thermal conductivity of 4.7 W/mK). The pipe is directly under an HVAC vent, and air at 21C is being blown over the pipe. This results in a conductive heat transfer coefficient of 129 W/m²K. If the convective heat transfer coefficient between the water and the pipe is 350 W/m?K, what is the overall heat transfer coefficient? What is the rate of heat 5. transfer from the water to the air?

Hot water (specific heat of 4.18 Kj/kgK) at 66C is flowing through a metal pipe (6 m long, 2 cm ID, 2.75 OD, thermal conductivity of 4.7 W/mK). The pipe is directly under an HVAC vent, and air at 21C is being blown over the pipe. This results in a conductive heat transfer coefficient of 129 W/m²K. If the convective heat transfer coefficient between the water and the pipe is 350 W/m?K, what is the overall heat transfer coefficient? What is the rate of heat 5. transfer from the water to the air?

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter7: Forced Convection Inside Tubes And Ducts

Section: Chapter Questions

Problem 7.27P

See similar textbooks

Similar questions

Determine the rate of heat transfer per meter length to a light oil flowing through a 2.5-cm-ID, 60-cm-long copper tube at a velocity of 0.03 m/s. The oil enters the tube at 16C, and the tube is heated by steam condensing on its outer surface at atmospheric pressure with a heat transfer coefficient of 11.3 kW/m K. The properties of the oil at various temperatures are listed in the following table: Temperature, T(C) 15 30 40 65 100 (kg/m3) 912 912 896 880 864 c(kJ/kgK) 1.80 1.84 1.925 2.0 2.135 k(W/mK) 0.133 0.133 0.131 0.129 0.128 (kg/ms) 0.089 0.0414 0.023 0.00786 0.0033 Pr 1204 573 338 122 55
3.10 A spherical shell satellite (3-m-OD, 1.25-cm-thick stainless steel walls) re-enters the atmosphere from outer space. If its original temperature is 38°C, the effective average temperature of the atmosphere is 1093°C, and the effective heat transfer coefficient is , estimate the temperature of the shell after reentry, assuming the time of reentry is 10 min and the interior of the shell is evacuated.
7.43 Liquid sodium is to be heated from 500 K to 600 K by passing it at a flow rate of 5.0 kg/s through a 5-cmID tube whose surface is maintained at 620 K. What length of tube is required?
Estimate the rate of heat loss per unit length from a 5-cm ID, 6-cm OD steel pipe covered with high-temperature insulation having a thermal conductivity of 0.11 W/(m K) and a thickness of 1.2 cm. Steam flows in the pipe. It has a quality of 99% and is at 150C. The unit thermal resistance at the inner wall is 0.0026(m2K)/W the heat transfer coefficient at the outer surface is 17W/(m2K) and the ambient temperature is 16C.
Water at a temperature of 77C is to be evaporated slowly in a vessel. The water is in a low-pressure container surrounded by steam as shown in the sketch below. The steam is condensing at 107C. The overall heat transfer coefficient between the water and the steam is 1100W/m2K. Calculate the surface area of the container that is required to evaporate water at a rate of 0.01 kg/s. Problem 1.16
Hot water (specific heat of 4.18 Kj/kgK) at 66C is flowing through a metal pipe (6 m long, 2 cm ID, 2.75 OD, thermal conductivity of 4.7 W/mK). The pipe is directly under an HVAC vent, and air at 21C is being blown over the pipe. This results in a conductive heat transfer coefficient of 129 W/m²K. If the convective heat transfer coefficient between the water and the pipe is 350 W/m²K, what is the overall heat transfer coefficient? What is the rate of heat 5. transfer from the water to the air?
3. Hot water flows inside a 2.5 cm inner diameter tube, the tube has a wall thickness of 0.8 mm (tube length=1m) with a conduction resistance of 0.000183 °C /W, the inner and outer convection resistance are (0.00662, 1.196 °C /W) respectively. The overall heat transfer coefficients depending on the outer diameter of the pipe is equal to: A. 9.94 W/m2 °C B. 200 W/m² °C C. 0.5 W/m² °C D. None of them
An electric motor is to be connected by a horizontal steel shaft (k 42.56 W/m.K), 25 mm in diameter to an impeller of a pump, circulating liquid metal at a temperature of 540°C. If the temperature of electric motor is limited to a maximum value of 52°C with the ambient air at 27°C and heat transfer coefficient of 40.7 W/m2.K, what length of shaft should be specified between the motor and pump? Steel shaft
a) A turbine blade 6 cm long and having a cross sectional area 4.65 cm and perimeter 12 cm is made of stainless steel (k=23.3 Wim K). The temperature at the root is 500 C. The blade is exposed to a hot gas at 870 °C. The heat transfer coefficient between the blade surface and gas is 442 W/im K. Determine the temperature distribution and rate of beat flow at the root of the blade, Assume the tip of the blade to be insulated. b) The hot combustion gases of a fumace are separated from the ambient air and its surounding, which are at 20°C, by a brick wall 0.5 m thick. The brick has a themal conductivity of 5 W/mk and a surface emissivity of 0.6. Under steady-state conditions an Page no.1 of 1 outer surface temperature of 120°C is measured Free convection heat transter to the air adjoining the surface is characterized by a convection coefficient of 15 Wim K What is the brick inner surface temperature
A steel duct whose internal diameter is 5.0 cm, and external diameter is 7.6 cm and thermal conductivity is: k = 15.0 (W/(m ºC)) is covered with an insulating material whose thickness is 2.0 cm and of thermal conductivity k = 0.2 (W/(m ºC)). A hot gas flows through the interior of the duct at a temperature of 330.0 ºC that generates a heat transfer coefficient by forced convection h=400.0 (W/(m^2 · ºC)). The outer surface of the insulating layer is exposed to air whose temperature is 30.0 ºC with forced convection heat transfer surface h = 60.0 (W/(m^2 · °C)). As a process engineer and in charge of company operations, you have been asked to: i. Determine the heat loss experienced by the pipe along 10.0 m.ii. The temperature drops that are generated in the different thermal resistances of the system. That is, on the air side, the duct wall and on the hot gas side.
2. For a saturated dry steam at 1,500 KPa that passes through a 100 mm (OD) steel pipe with a thickness of 5 mm and a length of 100 meters. The steam line is insulated with a 50 mm thickness and a thermal conductivity of 0.25 W/m.C. For a mass flow rate of 600 kg of steam per hour. The surface film conductance of steam is h = 5,500 W/m?.C, surface film conductance of air is h = 12 W/m?.C , thermal conductivity of pipe material is k = 153 W/m.C and the ambient air temperature is -10°C . Determine the following: a) The quality of steam after passing through the pipe b) Explain the concepts/principles that were considered and the factors that affected the condition of the above mentioned items (a & b) @ 1,500 KPa (tsat = 198.32°C) kJ 2,792.20- kg k] 844.89 kg kJ 1,947.30- kg 1 hg 2 hf hfg
1. Saturated steam at 500 K flows in a 0.20 m inside diameter, 0.21 m outside diameter pipe. The pipe is covered with 0.075 m of insulation with a thermal conductivity of 0.10 W/m-K. The pipe's conductivity is 52 W/m-K. The ambient temperature is 300 K. The unit convective coefficients are hi = 18,000 W/m²-K and ho 12 W/m²-K. Determine the heat loss (kJ/min) from 5 m of pipe.