Chapter 1 Basics of Heat Transfer1-125 Water is to be heated steadily from 15°C to 50°C by an electrical resistor inside an insulated pipe. The power rating of the resistance heater and the average velocity of the water are to be determined. Assumptions1This is a steady-flow process since there is no change with time at any point within the system and thus ΔΔmECVCVand ==00,. 2 Water is an incompressible substance with constant specific heats.3 The kinetic and potential energy changes are negligible, ΔΔkepe≅≅0 .4 The pipe is insulated and thus the heat losses are negligible.PropertiesThe density and specific heat of water at room temperature are ρ= 1000 kg/m3and C= 4.18 kJ/kg·°C (Table A-9). Analysis(a) We take the pipe as the system. This is a control volumesince mass crosses the system boundary during the process. Also, there is only one inlet and one exit and thus . The energy
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This note was uploaded on 01/14/2012 for the course PHY 4803 taught by Professor Dr.danielarenas during the Fall '10 term at UNF.