Unformatted text preview: energy balance relation can be written as 22 ° C 50,000 kJ/h water 80 ° C ( ) ( ) air water out , energies etc. potential, kinetic, internal, in Change system mass and work, heat, by nsfer energy tra Net © U U U Q W E E E in e out in Δ + Δ = Δ = − Δ = − 43 42 1 43 42 1 & [ ( )] , W t Q m C T T e in out Δ − = − 2 1 water Substituting, (15 kJ/s) Δ t (50,000 kJ/h)(10 h) = (1000 kg)(4.18 kJ/kg· ° C)(22  80) ° C It gives Δ t = 17,170 s = 4.77 h ( b ) If the house incorporated no solar heating, the 1st law relation above would simplify further to & , W t Q e in out Δ − = Substituting, (15 kJ/s) Δ t (50,000 kJ/h)(10 h) = 0 It gives Δ t = 33,330 s = 9.26 h 166...
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 Fall '10
 Dr.DanielArenas
 Thermodynamics, Mass, Heat, ΔT, constant specific heats, Solar heated water

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