7- 47.8 ΔΔ±±..Emgzp==−×⋅⋅⋅=−×⋅−10 m10 Lkg H OmmN1 J2.778 10 kW hh1 mLs1 kg m/ s1 N mkW h h533232219817511204 1074The maximum energy to be gained equals the potential energy lost by the water, or 2.0410 kW h24 h7 daysh1 day 1 weekkW h week (more than sufficient)4×⋅=×⋅343 106. 7.9 (b)QW U EEkp−= ++ΔΔΔEEkp==00system is stationaryno height changebgQW UQ W−=< >Δ,,00(c)E+ΔQWEEkp==00adiabatic , no moving parts or generated currentssystem is stationaryno height changebgΔΔΔU=0 (d).E+ΔWEEkp===000no moving parts or generated currentssystem is stationaryno height changeΔΔQUQ=<Δ,0Even though the system is isothermal, the occurrence of a chemical reaction assures that ΔU≠0 in a non-adiabatic reactor. If the temperature went up in the adiabatic reactor, heat must be transferred
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