Hot water (Cp= 4.188 kJ/kg.K) with mass flow rate of 2.5 kg/s at 100 C enters a thin-walled concentric tube counterflow heat exchanger with a surface area of 23 m^2 and an overall heat transfer coefficient of 1000 W/m^2.K. Cold water (Cp= 4.178 kJ/kg.K) with mass flow rate of 5 kg/s enters the heat exchanger at 20 C. (A) Use the Effectiveness-_NTU method, determine the heat transfer rate for the heat exchanger. (B) Determine the outlet temperatures of the cold and hot fluids. (C) After a period of operation, the overall heat transfer coefficient is reduced to 500 W/m^2.K. determine the fouling factor that caused the reduction in the overall heat transfer coefficient.

Hot water (Cp= 4.188 kJ/kg.K) with mass flow rate of 2.5 kg/s at 100 C enters a thin-walled concentric tube counterflow heat exchanger with a surface area of 23 m^2 and an overall heat transfer coefficient of 1000 W/m^2.K. Cold water (Cp= 4.178 kJ/kg.K) with mass flow rate of 5 kg/s enters the heat exchanger at 20 C. (A) Use the Effectiveness-_NTU method, determine the heat transfer rate for the heat exchanger. (B) Determine the outlet temperatures of the cold and hot fluids. (C) After a period of operation, the overall heat transfer coefficient is reduced to 500 W/m^2.K. determine the fouling factor that caused the reduction in the overall heat transfer coefficient.

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 7.54P

See similar textbooks

Similar questions

Hot water (Cp= 4.188 kJ/kg.K) with mass flow rate of 2.5 kg/s at 100 C enters a thin-walled concentric tube counterflow heat exchanger with a surface area of 23 m, and an overall heat transfer coefficient of 1000 W/m^2K. Cold water (Cp= 4.178 kJ/kg.K) with mass flow rate of 5 kg/s enters the heat exchanger at 20 C. After a period of operation, the overall heat transfer coefficient is reduced to 500 W/m^2K determine the fouling factor that caused the reduction in the overall heat transfer coefficient.
QUESTION 8 Cold water (C, = 4180 J/kg.°C) enters the tubes of a heat exchanger with 2-shell passes and 20 tube passes at 20 °C at a rate of 3 kg/s, while hot oil (C, = 2200 J/kg.°C) enters the shell at 130 °C at the same mass flow rate and leaves at 60°C. If the overall heat transfer coefficient based on the outer surface of the tube is 300 W/m².°C, determine; i. the rate of heat transfer and ii. the heat transfer surface area on the outer side of the tube.
A body is desired to be heated with hot water and oil on the body side in a heat exchanger with 20 pipe passes. The inner and outer diameters of the copper pipe are 20 and 24 mm, respectively. Water with a flow rate of 0.2 kg / s enters the pipe at 87 ° C and leaves at 43 ° C. The inlet and outlet temperatures of the oil in the heat exchanger are 7 ° C and 37 ° C, respectively. Average heat transfer coefficient on the outer surface of the pipes is 800 W / m ° K. The fouling resistances on both sides are negligible.Determine;a) Heat transfer b) External surface based total heat transfer coefficient, c) Determine the pipe length in one pass.
5. Hot exhaust gases, which enter a finned-tube, cross-flow heat exchanger at 300 °C and leave at 100 °C, are used to heat pressurized water at a flow rate of 1 kg/s from 35 °C 125 °C. The specific heat of water at the average water temperature is 4197 J/kg. K. The overall heat transfer coefficient based on the gas-side surface area is U₁ = 100 W/m².K. Determine the required gas-side surface area A₁ using the LMTD and & -NTU method.
A counterflow double-tube heat exchanger with hot engine oil fluid at inlet and outlet temperatures of 190°C and 60°C, respectively, and a flow rate of 0.65 kg/s. While cold engine oil at a flow rate of 1.05 kg/s has an exit temperature of 149°C and Cp-1.84 kJ/kg.K. It is known that the overall heat transfer coefficient is 305 W/m².K. Determine the heat transfer surface area of the heat exchanger.
1. A long thin-walled double-pipe heat exchanger with tube and shell diameters of 1.0 cm and 2.5 cm, respectively, is used to condense refrigerant-134a by water at 20 0C. The refrigerant flows through the tube, with a convection heat transfer coefficient of 5000 W/m2 K. Water flows through the shell at a rate of 0.3 kg/s. Determine the overall heat transfer coefficient of this heat exchanger. If a 2-mm-thick layer of limestone (k = 1.3 W/m K) forms on the outer surface of the inner tube what will be new overall heat transfer coefficient
A counterflow, concentric tube heat exchanger used for engine cooling has been in service for an extended period of time. The heat transfer surface area of the exchanger is 5 m^2, and the design value of the overall convection coefficient is 38 W/m^2-K. During a test run, engine oil flowing at 0.1 kg/s is cooled from 110°C to 66°C by water supplied at a temperature of 25°C and a flow rate of 0.2 kg/s. Determine whether fouling has occurred during the service period. If so, calculate the fouling factor, R"f(m^2• K/W).
Water enters at 20 °C at a rate of 0.1 kg/s in a double-pipe counter flow heat exchanger is to be heated by hot air that enters the heat exchanger at 100 °C at a rate of 0.3 kg/s. The overall heat transfer coefficient based on the inner side of the tube to be 100 W/m2. "C. The length of the tube is 14 m and the internal diameter of the tube is 1.4 cm. Determine the outlet temperature of the air. The specific heats of the water and air are given to be 4.18 and 1.01 k/kg."C. respectively. Select one: O a. 82.6 °C O b. 74.7 C O c. 72.5 C O d. 86.2 C
A 10-m-long countercurrent-flow heat exchanger is being used to heat a liquid food from 20 to 80 C. The heating medium is oil, which enters the heat exchanger at 150 C and exits at 60 C. The specific heat of the liquid food is 3.9 kJ/(kg K). The overall heat-transfer coefficient based on the inside area is 1000 W/ (m2 K). The inner diameter of the inside pipe is 7 cm. a. Estimate the flow rate of the liquid food. b. Determine the flow rate of the liquid food if the heat exchanger is operated in a concurrent-flow mode for the same conditions of temperature at the inlet and exit from the heat exchanger.
Glycerin (cp=2400 J/kg*K) at 20°C and 1 kg/s is to be heated by ethylene glycol (cp = 2500 J/kg*K) at 75°C and the same mass flow rate in a thin-walled double-pipe parallel-flow heat exchanger. If the overall heat transfer coefficient is 380 W/m²*K and the pipe is 75m long and 2.5cm in diameter, determine (a) the rate of heat transfer and (b) the outlet temperatures of the glycerin and the glycol.
A single-pass, cross-flow heat exchanger uses hot exhaust gases (mixed) to heat water (unmixed) from 30°C to 80°C at a rate of 5.25 kg/s. The exhaust gases enter and exit the exchanger at 225°C and 100°C, respectively. What is the mass flow rate of the hot gases (kg/s) ? Water : c = 4184 J/kg K, Hot gases 1019 J/kg K :c = Select one: %3D
A one-shell pass and two-tube passes heat exchanger cools 1.8 L/s of oil (cp = 2.5 kJ/kg-K and density = 720 kg/m3) from 94 C to 48 C. Cooling water enters the tubes at 15 C and leaves at 40 C. The overall coefficient of heat transfer is 450 W/m2-K. Fouling of the tubes occurs, resulting in one-quarter of the tubes being blocked. The conditions remain the same except for the outlet temperatures. Determine the (a) oil exit temperature (1 decimal place) and (b) water exit temperature (1 decimal place) under the new condition.