2-b 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 to 125 °C. The specific heat of water at the average water temperature is 4197 J/kg. K. The overall heat transfers coefficient based on the gas-side surface area is Un = 100 W/m².K. Determine the required gas-side surface area A, using the LMTD and E-NTU method.

2-b 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 to 125 °C. The specific heat of water at the average water temperature is 4197 J/kg. K. The overall heat transfers coefficient based on the gas-side surface area is Un = 100 W/m².K. Determine the required gas-side surface area A, using the LMTD and E-NTU method.

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.

Chapter10: Heat Exchangers

Section: Chapter Questions

Problem 10.20P

See similar textbooks

Similar questions

Geothermal heat pumps, or water-source heat pumps, are classified as either _____loop or _____loop systems.
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.
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
5) During an experiment, a plate heat exchanger that is used to transfer heat from a hot-water stream to a cold-water stream is tested, and the following measurements are taken: Hot water Cold water stream stream 38.9 Inlet temperature, °C Outlet temperature, "C Volume flow rate, L/min 14.3 27.0 19.8 2.5 4.5 The heat transfer arca is calculated to be 0.0400 m. (a) Calculate the rate of heat transfer to the cold water. (b) Calculate the overall heat transfer coefficient. (c) Determine if the heat exchanger is truly adiabatic. If not, determine the fraction of heat loss and calculate the heat transfer efficiency. (d) Determine the effectiveness and the NTU values of the heat exchanger. (Answers: (a) 1724 W (b) 3017 Wiw C (c) the heat exchanger is not adiabatic so heat loss 16.4% and heat transfer efficiency 83.6% (d) effectiveness 44.4% and NTU 0.697) Hot water 38.9°C 19.8°C Cold water 14.3°C 27.0°C
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 Uh = 100 W/m².K. Determine the required gas-side surface area A₁ using the LMTD and & -NTU method.
2- In a heat exchanger, steam of 0.08 bar and a specific steam content of 95% is condensed. 381.6 tons / h cooling water with a temperature of 10 ̊C flows in parallel connected tubers with inner / outer diameter 28/30 mm with a speed of 0.65 m / s. The heat transfer surface of the heat exchanger is 220 m2 and it has a k-value of 2200 W / (m2K) . Assume the specific heat capacity of the water 4.18 kJ / (kg K) and density 1000 kg / m3. The K-value is attributed to the outer mantle surface of the tubes. a) Calculate the outlet temperature of cooling water. b) How many tonnes of steam per hour are condensed? c) Determine the number of tubes and tube length
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.
In a parallel flow heat exchanger, with a cooler at 40 °C at a flow of 2 kg / h, hot water at 1 kg / h is cooled from 90 ° C to 60 ° C. The total heat transfer coefficient is 1000 W / m2K. Cph = Cpc = 4182 J / kgK. According to this; b) Determine the required space for the counterflow heat exchanger case.
Question 2 En. Karim recently install a hot water system operates by a solar energy. The system consists of double pipe counter flow heat exchanger. Cold waters enters a tube at 22°C at a rate of 0.1 kg/s, while hot air enters the heat exchanger at 90°C at a rate of 0.3 kg/s. The specific heat for both cold water and hot air is cp = 4180 J/kg.K and c, = 1010 J/kg.K , respectively. The overall heat transfer coefficient based on the inner side of the tube is 80 W/m².K. The length of the tube is 12 m and the internal diameter of the tube is 1.2 cm. En. Karim assigned you do the complete analysis on this hot water system including to calculate the effectiveness of the heat exchanger. As an engineer, you have to determine: i. the heat capacity rates of both fluids, ii. the maximum rate of heat transfer (kW), iii. the effectiveness of the heat exchanger (NTU method), iv. the actual rate of heat transfer (kW), and v. the outlet temperatures of both cold water and hot air.
2. A concentric counterflow heat exchanger is used to cool oil by water. The oil flow rate is 0.1 kg/s and enters at 100 C. Water enters at 30 C and a flow rate of0.2 kg/s. The heat transfer area is 5.223 m2 and the overall heat transfer coefficient is 37.8 W/m2·K. Find the rate of heat transfer and exit temperatures. Data: Cp,h = 2131 J/kg·K and Cp,c = 4178 J/kg·K. [Ans.: Q = 8524 W, Tho = 60 C, and Tco = 40 C].
Water at the rate of 86 kg/min is heated from 20 to 70-C by an oil having a specific heat of 1.9 kJ/kg.-C. The fluids are used in a counterflow double-pipe heat exchanger, and the oil enters the exchanger at 110-C and leaves at 70-C. The overall heat-transfer coefficient is 230 W/m2.-C. Calculate the heat transfer rate, kW. (A) 136.2 B) 189.5 300.0 (D) 108.9