Water is to be heated from 20°C to 70°C as it flows through a 40 mm Inter diameter and 600 mm long tube. The outer surface of the tube is wrapped with electrical wire which acts as an electrical resistance heater. The heater provides uniform heat flux throughout the surface of the tube. The outer surface of the heater is well insulated. At steady state if the system provides hot water at 0.2475 kg/s, determine the power rating of the resistance heater and the inner surface temperature of the pipe at the exit. p = 990 kg/m³: k Pr-4.328 = 0.631 W/(m K); c = 4180 J/(kg K); v = 0.66 x 10-6 m²/s:

Water is to be heated from 20°C to 70°C as it flows through a 40 mm Inter diameter and 600 mm long tube. The outer surface of the tube is wrapped with electrical wire which acts as an electrical resistance heater. The heater provides uniform heat flux throughout the surface of the tube. The outer surface of the heater is well insulated. At steady state if the system provides hot water at 0.2475 kg/s, determine the power rating of the resistance heater and the inner surface temperature of the pipe at the exit. p = 990 kg/m³: k Pr-4.328 = 0.631 W/(m K); c = 4180 J/(kg K); v = 0.66 x 10-6 m²/s:

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 7.17P: Determine the rate of heat transfer per meter length to a light oil flowing through a 2.5-cm-ID,...

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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?
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
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n electric generator at a power plant produces energy by passing superheated steam from a high temperature container (reservoir), through a pipe connected to a series of fans, and then into a low temperature reservoir. As the steam passes across the blades of the fans some of the heat energy of the steam is transformed into mechanical energy, which turns the fans which in turn are connected to a generator, which in turn converts the mechanical energy into electrical energy. If the high temperature steam has a temperature of 412.1 K and the low temperature reservoir has a temperature of 105.4 K, what is the Carnot efficiency of this process?
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Steam generators are a type of heat exchanges that are used in power plants to generate steam at desired pressure and temperature (Fig. Q1.b). In a steam generator, saturated liquid water at 30°C enters a 60-mm diameter tube at the volume flow rate of 12 L/s. After exchanging heat with hot gas, the water changes to steam and leaves the generator at a pressure of 9 MPa and a temperature of 400°C. During this process, the diameter of the water/steam tube does not change.(iii) What is the exit velocity of the steam?
By superheating the stream to a high temperature, the average steam temperature during heat rejection can be increased. True or False
Steam generators are a type of heat exchanges that are used inpower plants to generate steam at desired pressure andtemperature (Fig. Q1.b). In a steam generator, saturated liquidwater at 30°C enters a 60-mm diameter tube at the volume flowrate of 12 L/s. After exchanging heat with hot gas, the waterchanges to steam and leaves the generator at a pressure of 9 MPaand a temperature of 400°C. During this process, the diameter ofthe water/steam tube does not change. Where necessary, assume air as an ideal gas and consider R = 287J/(kg.K), Cp = 1005 J/(kg.K), Cv = 718 J/(kg.K). (i) Calculate the steam mass flow rate and inlet velocity of the steam? (ii) What is the exit velocity of the steam? (iii) Calculate the rate of heat transfer (in MW) required tochange the phase of liquid water to steam.
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