Temperature thermovsheattransferexample consider

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Unformatted text preview: ge. temperature Thermo vs. Heat Transfer – Example Consider cooling a steel bar by placing it in water Thermodynamics final temperature of the steel - water system final Heat transfer temperature of the bar and the water as a temperature function of time function how long it will take to reach equilibrium temperature profile within the bar Both are useful Heat transfer concerns energy in transit due to Heat energy a temperature difference temperature Modes of Heat Transfer Conduction Temperature gradient in a stationary medium (solid or fluid, rarely gas) Convection Heat transfer between a surface and a moving fluid at different temperatures Radiation Surfaces of finite temperature emit energy in the form of electromagnetic waves Nomenclature T - Temperature [=] oC, K, oF, R Temperature C, Q - Heat (from 1st law of thermo) [=] Joules, Btu Heat q - Heat transfer rate [=] Joules/s = Watts Heat q′′ - Heat flux [=] W/m2 [=] q′′′ - Rate of heat generation [=] W/m3 [=] Subscripts - x, y, z, r, θ, φ qx - heat is flowing in the x direction heat q′′ - radial heat flux r radial Conduction • Conduction – Place one end of a steel bar in a fi...
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