A heat exchanger (cross flow) consists of 40 tubes with 1cm diameter located in a square of 1m by 1m. Cold water( cp=4180 J/kg C) enters the tubes at 18C with an average velocity of 3m/s. Hot air (cp=1010 J/kg C) by that time enters thechannel at 130C and 105 kPa at an average velocity of 12 m/s. if the overall heat transfer coefficient is 130 W/m2C,determine(a) the output temperatures of both fluids(b) the rate of heat transfer.Hints: There is no fin attached to the tubes.1 mHot air130°C105 kPaWater12 m/s18°C3 m/s000

Given data as per question No. of tubes = 40 tubes Diameter of the tubes = 1 cm Cold water…

Answered: A heat exchanger (cross flow) consists…

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 7.14P

See similar textbooks

Similar questions

10.1 In a heat exchanger, as shown in the accompanying figure, air flows over brass tubes of 1.8-cm 1D and 2.1-cm OD containing steam. The convection heat transfer coefficients on the air and steam sides of the tubes are , respectively. Calculate the overall heal transfer coefficient for the heal exchanger (a) based on the inner tube area and (b) based on the outer tube area.
Water flowing in a long, aluminum lube is to be heated by air flowing perpendicular to the exterior of the tube. The ID of the tube is 1.85 cm, and its OD is 2.3 cm. The mass flow rate of the water through the tube is 0.65kg/s, and the temperature of the water in the lube averages 30C. The free-stream velocity and ambient temperature of the air are 10m/sand120C, respectively. Estimate the overall heat transfer coefficient for the heat exchanger using appropriate correlations from previous chapters. State all your assumptions.
In order to cool a mass flow rate of 25 Kg/h of air (cp = 1060 J/Kg oC) at 300 oC, it is passed through the tube side of a counter flow heat exchanger with a length of 2 m and 2.54 cm tube outer diameter. The cooling water, (cp = 4182 J/Kg oC and r = 1000 Kg/m3), enters the heat exchanger at a temperature of 30 oC with a volume flow rate of 0.3 Litre/min. If the overall heat transfer coefficient, U, is 5.83 W/m2 oC and the effectiveness of the heat exchanger 60 %, calculate the following: The heat transfer rate, The exit temperatures of both the water and the air, The surface area of the heat exchanger, The number of tubes used in the heat exchanger The capacity rate ratio.
A long thin-walled double-pipe heat exchanger with tube and shell diameters of 2 cm and 4 cm, respectively, is used to condense refrigerant-134a by water at 20 C. The refrigerant flows through the tube, with a convection heat transfer coefficient of hi = 4000 W/m2 K.A 1-mm-thick layer of limestone (k = 1.2 W/mK) forms on the outer surface of the inner tube. Water flows through the shell at a rate of 0.4 kg/s. Determine the overall heat transfer coefficient U of this heat exchanger with and without the fouling factor, and the error in U introduced by neglecting the fouling factor. Comment the fouling effect on this heat exchanger.
A cross-flow heat exchanger with both fluids unmixed has an overall heat transfer coefficient of 200 W/m2·K, and a heat transfer surface area of 400 m2. The hot fluid has a heat capacity of 40,000 W/K, while the cold fluid has a heat capacity of 80,000 W/K. If the inlet temperatures of both hot and cold fluids are 80°C and 20°C, respectively, determine (a) the exit temperature of the hot fluid and (b) the rate of heat transfer in the heat exchanger.
A thin-walled double-pipe counter-flow heat exchanger is to be used to cool oil (Cpo= 2200 J/kg.K) from 150°C to 40°C at a rate of 2 kg/s by water (Cpw= 4180 J/kg.K) that enters at 22°C at a rate of 1.5Kg/s. If the diameter of the tube is 2.5 cm, and its length is 6 m, determine * The rate of heat transfer in the heat exchanger * The outlet temperature of the cold fluid * The Log Mean Temperature Difference (LMTD) * The overall heat transfer coefficient
Engine oil at 20°C is to be heated to a temperature of 60°C by saturated steam at 1 atm in a double-pipe heat exchanger. The inner and outer diameters of the annular space are 4 cm and 6 cm, respectively, and engine oil enters the inner tube with a mean velocity of 0.8 m/s. The inner tube surface may be assumed to be isothermal at 100°C, and the outer tube is well insulated. Assuming fully developed Poiseulle flow for oil, determine the rate of heat transfer to the oil from the tube surface and find the tube length required to heat the oil to the indicated temperature using the empirical relations associated with convection heat transfer.
Hot oil is to be cooled in a double-tube counter-flow heat exchanger. The copper inner tubes have a diameter of 2 cm and negligible thickness. The inner diameter of the outer tube (the shell) is 3 cm. Water flows through the tube at a rate of 0.5 kg/s, and the oil through the shell at a rate of 0.8 kg/s. Taking the average temperatures of the water and the oil to be 45°C and 80°C, respectively, determine the overall heat transfer coefficient of this heat exchanger.
Consider the flow of saturated steam at 270.1 kPa that flows through the shell side of a shell-and-tube heat exchanger while the water flows through 4 tubes of diameter 1.25 cm at a rate of 0.25 kg/s through each tube. The water enters the tubes of heat exchanger at 20°C and exits at 60°C. Due to the heat exchange with the cold fluid, steam is condensed on the tubes external surface. The convection heat transfer coefficient on the steam side is 1500 W/m2·K, while the fouling resistance for the steam and water may be taken as 0.00015 and 0.0001 m2·K/W, respectively. Using the NTU method, determine (a) effectiveness of the heat exchanger, (b) length of the tube, and (c) rate of steam condensation.
Hot oil is to be cooled in a double-tube counter-flow heat exchanger. The copper inner tubes have a diameter of 2 cm and negligible thickness. The inner diameter of the outer tube (the shell) is 3 cm. Water flows through the tube at a rate of 0.5 kg/s. The Nusselt number for the forced convection between the oil and the external surface of the tube is Nuo = 5.45. If the length of the tube is 1m and ΔTlm = 45°C. Determine the rate of heat transfer. Water properties: ρ = 990 kg/m3, Pr = 3.91, k = 0.637 W/m °C, ν = 0.000000602 m2/s. Oil properties: k = 0.138 W/m °C Select one: a. 261 W b. 745 W c. 567 W d. 421 W
A cross-flow heat exchanger with both fluids unmixed has an overall heat transfer coefficient of 200 W/m2·K, and a heat transfer surface area of 400 m2. The hot fluid has a heat capacity of 40,000 W/K, while the cold fluid has a heat capacity of 80,000 W/K. If the inlet temperatures of both hot and cold fluids are 80°C and 20°C, respectively, determine the exit temperature of the cold fluid.
Hot oil is to be cooled in a double-tube counter-flow heat exchanger.The copper inner tubes have a diameter of 2 cm and negligible thickness. The inner diameter of the outer tube (the shell) is 3 cm. Water flows through the tube at a rate of 0.5 kg/s, and the oil through the shell at a rate of 0.8 kg/s. Taking the average temperatures of the water and the oil to be 45 C and80 C, respectively, determine the overall heat transfer coefficient of this heat excha nger.

SEE MORE QUESTIONS

Recommended textbooks for you

Principles of Heat Transfer (Activate Learning wi…

Mechanical Engineering

ISBN:

9781305387102

Author:

Kreith, Frank; Manglik, Raj M.

Publisher:

Cengage Learning