Explanation Given: Water volume flow rate of water ( V ˙ ) is of 10 L/min. The initial temperature of the water ( T 1 ) is 16 ° C . The final temperature of the water ( T 2 ) is 43 ° C . The density of the water ( ρ ) is 1 kg/L . The temperature of drained warm water ( T max ) is 39 ° C . The effectiveness of heat exchanger ( ε ) ranges from is 20 % to 90%. The price of the electric energy is 11.5 ¢/kWh. The duration of shower ( t ) is 10 min. Calculation: Calculate the mass flow rate of water from density. m ˙ = ρ V ˙ m ˙ = 1 kg / L × 10 L / min = 10 kg / min Write the energy balance equation for the steady state flow system. E ˙ in − E ˙ out = Δ E ˙ system E ˙ in − E ˙ out = 0 ( steady state ) W ˙ e,in = m ˙ ( h 2 − h 1 ) W ˙ e,in = m ˙ [ c ( T 2 − T 1 ) + v ( P 2 − P 1 ) ︸ = 0 ] W ˙ e,in = m ˙ c ( T 2 − T 1 ) (I) Here, net rate of energy input to the system is E ˙ in , net rate of energy output from the system is E ˙ out , net rate of change in energy is Δ E ˙ system , specific enthalpy at the initial condition is h 1 , specific enthalpy at final condition is h 2 , work input to the electrical resistance heater is W ˙ e,in , constant pressure specific heat is c , final temperature is T 2 , initial temperature is T 1 , specific volume of water is v , final pressure is P 2 and the initial pressure is P 1 . Refer Table A-3, “Properties of common liquids, solids and gases”, obtain the density of water and constant pressure specific heat of water as 1 kg / L and 4.18 kJ / kg ° C respectively. Substitute m ˙ = 10 kg / min , c = 4.18 kJ / kg ° C , T 2 = 43 ° C , and T 1 = 16 ° C in Equation (I). W ˙ e,in = 10 kg / min × 1 min 60 s × 4.18 kJ / kg ° C × ( 43 ° C − 16 ° C ) = 10 kg / min × 1 min 60 s × 4

Fundamentals Of Thermal-fluid Sciences In Si Units

5th Edition

ISBN: 9789814720953

Author: Yunus Cengel, Robert Turner, John Cimbala

Publisher: McGraw-Hill Education

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Fundamentals Of Thermal-fluid Sciences In Si Units

Ch. 6 - Prob. 1P Ch. 6 - Define mass and volume flow rates. How are they...Ch. 6 - Does the amount of mass entering a control volume...Ch. 6 - Consider a device with one inlet and one outlet....Ch. 6 - The ventilating fan of the bathroom of a building...Ch. 6 - Air whose density is 0.078 lbm/ft3 enters the duct...Ch. 6 - Air enters a 28-cm diameter pipe steadily at 200...Ch. 6 - A steady-flow compressor is used to compress...Ch. 6 - Prob. 9P Ch. 6 - A desktop computer is to be cooled by a fan whose...

Ch. 6 - Prob. 11P Ch. 6 - Prob. 12P Ch. 6 - Prob. 13P Ch. 6 - Prob. 14P Ch. 6 - Prob. 15P Ch. 6 - Prob. 16P Ch. 6 - A house is maintained at 1 atm and 24°C, and warm...Ch. 6 - Prob. 18P Ch. 6 - Prob. 19P Ch. 6 - Prob. 20P Ch. 6 - Prob. 21P Ch. 6 - The kinetic energy of a fluid increases as it is...Ch. 6 - Prob. 23P Ch. 6 - Air enters a nozzle steadily at 50 psia, 140°F,...Ch. 6 - Prob. 25P Ch. 6 - Prob. 26P Ch. 6 - Air at 600 kPa and 500 K enters an adiabatic...Ch. 6 - Prob. 28P Ch. 6 - Prob. 29P Ch. 6 - Air at 13 psia and 65°F enters an adiabatic...Ch. 6 - Prob. 31P Ch. 6 - Prob. 32P Ch. 6 - Prob. 33P Ch. 6 - Steam at 4 MPa and 400°C enters a nozzle steadily...Ch. 6 - Prob. 35P Ch. 6 - Prob. 36P Ch. 6 - Prob. 37P Ch. 6 - Prob. 38P Ch. 6 - Prob. 39P Ch. 6 - Prob. 40P Ch. 6 - Prob. 41P Ch. 6 - Prob. 42P Ch. 6 - Prob. 43P Ch. 6 - Helium is to be compressed from 105 kPa and 295 K...Ch. 6 - Carbon dioxide enters an adiabatic compressor at...Ch. 6 - Air is compressed from 14.7 psia and 60°F to a...Ch. 6 - Prob. 47P Ch. 6 - An adiabatic gas turbine expands air at 1300 kPa...Ch. 6 - Steam flows steadily into a turbine with a mass...Ch. 6 - Prob. 50P Ch. 6 - Prob. 51P Ch. 6 - Prob. 52P Ch. 6 - Prob. 53P Ch. 6 - Prob. 54P Ch. 6 - Refrigerant-134a is throttled from the saturated...Ch. 6 - Prob. 56P Ch. 6 - Prob. 57P Ch. 6 - Prob. 58P Ch. 6 - Prob. 59P Ch. 6 - Prob. 60P Ch. 6 - Prob. 61P Ch. 6 - Prob. 62P Ch. 6 - Prob. 63P Ch. 6 - Prob. 64P Ch. 6 - Prob. 65P Ch. 6 - Prob. 66P Ch. 6 - Prob. 67P Ch. 6 - Prob. 68P Ch. 6 - Prob. 69P Ch. 6 - Prob. 70P Ch. 6 - A thin-walled double-pipe counter-flow heat...Ch. 6 - Prob. 72P Ch. 6 - Prob. 73P Ch. 6 - Prob. 74P Ch. 6 - Prob. 75P Ch. 6 - Prob. 77P Ch. 6 - Prob. 78P Ch. 6 - Prob. 79P Ch. 6 - Prob. 80P Ch. 6 - Prob. 81P Ch. 6 - Prob. 82P Ch. 6 - Prob. 83P Ch. 6 - Prob. 84P Ch. 6 - Prob. 85P Ch. 6 - The components of an electronic system dissipating...Ch. 6 - Prob. 87P Ch. 6 - Prob. 88P Ch. 6 - Prob. 89P Ch. 6 - Prob. 90P Ch. 6 - Prob. 91P Ch. 6 - Prob. 92P Ch. 6 - Prob. 93P Ch. 6 - A house has an electric heating system that...Ch. 6 - Prob. 95P Ch. 6 - Refrigerant-134a enters the condenser of a...Ch. 6 - Prob. 97P Ch. 6 - Prob. 98P Ch. 6 - Prob. 99P Ch. 6 - Prob. 100P Ch. 6 - Air enters the duct of an air-conditioning system...Ch. 6 - Prob. 102P Ch. 6 - A rigid, insulated tank that is initially...Ch. 6 - Prob. 105P Ch. 6 - Prob. 106P Ch. 6 - Prob. 107P Ch. 6 - Prob. 108P Ch. 6 - Prob. 109P Ch. 6 - An air-conditioning system is to be filled from a...Ch. 6 - Prob. 111P Ch. 6 - A 0.06-m3 rigid tank initially contains...Ch. 6 - A 0.3-m3 rigid tank is filled with saturated...Ch. 6 - Prob. 114P Ch. 6 - A 0.3-m3 rigid tank initially contains...Ch. 6 - Prob. 116P Ch. 6 - Prob. 117P Ch. 6 - An insulated 40-ft3 rigid tank contains air at 50...Ch. 6 - A vertical piston–cylinder device initially...Ch. 6 - A vertical piston–cylinder device initially...Ch. 6 - The air in a 6-m × 5-m × 4-m hospital room is to...Ch. 6 - Prob. 124RQ Ch. 6 - Prob. 125RQ Ch. 6 - Prob. 126RQ Ch. 6 - Prob. 127RQ Ch. 6 - Prob. 128RQ Ch. 6 - Prob. 129RQ Ch. 6 - Prob. 130RQ Ch. 6 - Prob. 131RQ Ch. 6 - Prob. 132RQ Ch. 6 - Steam enters a nozzle with a low velocity at 150°C...Ch. 6 - Prob. 134RQ Ch. 6 - Prob. 135RQ Ch. 6 - Prob. 136RQ Ch. 6 - In large steam power plants, the feedwater is...Ch. 6 - Prob. 138RQ Ch. 6 - Prob. 139RQ Ch. 6 - Prob. 140RQ Ch. 6 - Prob. 141RQ Ch. 6 - Prob. 142RQ Ch. 6 - Prob. 143RQ Ch. 6 - Prob. 144RQ Ch. 6 - Prob. 145RQ Ch. 6 - Prob. 146RQ Ch. 6 - Repeat Prob. 6–146 for a copper wire ( = 8950...Ch. 6 - Prob. 148RQ Ch. 6 - Prob. 149RQ Ch. 6 - Prob. 150RQ Ch. 6 - Prob. 151RQ Ch. 6 - Prob. 152RQ Ch. 6 - Prob. 153RQ Ch. 6 - An adiabatic air compressor is to be powered by a...Ch. 6 - Prob. 156RQ Ch. 6 - Prob. 157RQ Ch. 6 - Prob. 158RQ Ch. 6 - Prob. 159RQ Ch. 6 - Prob. 160RQ Ch. 6 - Prob. 161RQ Ch. 6 - Prob. 162RQ Ch. 6 - Prob. 163RQ Ch. 6 - Prob. 164RQ Ch. 6 - Prob. 166RQ Ch. 6 - Prob. 167RQ Ch. 6 - Prob. 168RQ Ch. 6 - Prob. 169RQ

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