In a large air-conditioning application, 1500 m3/min of air at 1 atm and 10◦C are to be heated in a finned-tube heat exchanger with hot water entering the exchanger at 80◦C. The overall heat-transfer coefficient is 50 W/m2 · ◦C. Calculate the required area for the heat exchanger for an exit air temperature of 37◦C and exit watertemperature of 48◦C.

In a large air-conditioning application, 1500 m3/min of air at 1 atm and 10◦C are to be heated in a finned-tube heat exchanger with hot water entering the exchanger at 80◦C. The overall heat-transfer coefficient is 50 W/m2 · ◦C. Calculate the required area for the heat exchanger for an exit air temperature of 37◦C and exit watertemperature of 48◦C.

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

In a large air-conditioning application, 1500 m3/min of air at 1 atm and 10◦C are tobe heated in a finned-tube heat exchanger with hot water entering the exchanger at 80◦C. The overall heat-transfer coefficient is 50 W/m2 · ◦C. Calculate the requiredarea for the heat exchanger for an exit air temperature of 37◦C and exit water temperature of 48◦C
An air-cooled condenser has an h value of 30 W/m2-K based on the air-side area. The air-side heat transfer area is 190 m2 with air entering at 27°C and leaving at 40°C. If the condensing temperature is constant at 49°C, what is the air mass flow rate in kg/s? Let Cp(air) = 1.006 kJ/kg-K. Draw and label the temperature-flow diagram. Round off your answer to three (3) decimal places.
Water enters a crossflow exchanger (with both fluids unmixed) at 16◦C and flows at 7.5 kg/s. It is used to cool air flowing at ◦22 10 kg/s which enters at 120 C. The exchanger has an overall heat transfer coefficient of 225 W/m /K and a surface area of 225 m . Data: Specific heat of air = 1014 J/kg/K; Specific heat of water = 4182 J/kg/K. (a Calculate the effectiveness of the exchanger(b Determine the heat transfer rate in the exchanger(c Determine the exit temperature of air(d After prolonged use the exchanger is affected by fouling, with a fouling factor of 2 × 10−3 m2/W/K. Determine the heat transfer rate in the exchanger with fouling.
Problem 2 An air-to-air heat recovery unit uses across-flow exchanger with both fluids unmixed and an airflow rate of 0.5 kg/s on both sides. The hot air enters at 400 °C while the cool air enters at 20 °C. Calculate the exit temperatures for U = 40 W/m². °C and a total exchanger area of 15 m². Take the specific heat of air 1006 J/kg.°c.
SOLVE THE PROBLEM AND SHOW THE DETAILED SOLUTION A steam condenser receives 10 kg per second of steam with an enthalpy of 2,570-kJ/kg. The steam condenses into liquid and leaves with an enthalpy of 160kJ/kg. Cooling water passes through the condenser with temperature increases from 13 to 24 Calculate the cooling water flow rate in kg/s.
A cross-flow heat exchanger is used to transfer heat from a stream of saturated water at 100 °C to a stream of air entering at 40 °C. The UA value of the heat exchanger is 5000 W/K. Develop an equation for the outlet temperature of the air as a function of the mass flow rate of air through the heat exchanger. Plot the outlet air temperature vs. mass flow rate of air from 0.5 kg/s to 20 kg/s.
6. A heat exchanger was installed purposely to cool 0.50 kg of gas per second. Molecular weight is 28 and k=1.32. The gas is cooled from 150 deg C to 80 deg C. Water is available at the rate of 0.30 kg/s and at a temperature of 12 deg C. Calculate the exit temperature of the water.
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.
Air (Cp = 1005 J/kg °C) enters a cross-flow heat exchanger at 10 C at a rate of 3 kg/s, where it is heated by a hot water stream (Cp = 4190 J/kg °C) that enters the heat exchanger at 95 °C at a rate of 1 kg/s. Determine the maximum heat transfer rate and the outlet temperatures of the cold and the hot water streams for that case.
Q1] A shell and tube heat exchanger is used to heat water (C = 4236 J/kg. °C) from 80°C to 150°C at a rate of 12.5 kg/s by hot gas that enters the exchanger at 350°C with a rate of 20.36 kg/s. The overall heat transfer coefficient is 290 W/m² °C. The gas making 2-shell passes and the water making 4-tube passes. Calculate the heat transfer surface area (Cp (gas) = 1.04 kJ/kg.°C). heat flux: (a) by
2. A heat exchanger like that is used to heat an oil in the tubes (c = 1.9 kJ/kg °C) from 15-C to 85 °C. Blowing across the outside of the tubes is steam that enters at 130-C and leaves at 110°C with a mass flow of 5.2 kg/sec. The overall heat-transfer coefficient is 275 W/m² °C and c for steam is 1.86 kJ/kg C. Calculate the surface area of the heat exchanger (Holman, 2002). 130 85 Steam Oil 110
Hot exhaust gases are used in a finned-tube cross-flow heat exchanger to heat 2.5 kg/s of water from 35 to 85-C. The gases [cp = 1.09 kJ/kg . °C] enter at 200 and leave at 93°C. The overall heat-transfer coefficient is 180 W/m2 • °C. Calculate the area of the heat exchanger using the LMTD approach.