Explanation Write the energy balance equation for a closed system for which the plate is taken as the system. E ˙ in − E ˙ out = Δ E ˙ system Here, rate of net energy transfer in to the control volume is E ˙ in , rate of net energy transfer exit from the control volume is E ˙ out and rate of change in internal energy of system is Δ E ˙ system . For steady-flow system, the rate of change in internal energy of system is zero. Δ E ˙ system = 0 Then, the energy balance equation is, E ˙ in − E ˙ out = 0 E ˙ in = E ˙ out Q ˙ in = m ˙ c p ( T 2 − T 1 ) (I) Here, rate of heat transfer to the milk is Q ˙ in , mass flow rate of the milk is m ˙ , specific heat capacity of the milk is c p , internal and temperatures of the milk at initial and final conditions are T 1 and T 2 respectively. Write the formula to calculate mass flow rate of the milk ( m ˙ ) . m ˙ = ρ V ˙ (II) Here, density of the milk is ρ , volume flow rate of the milk is V ˙ . Write the formula to calculate rate of heat transfer saved by the regenerator ( Q ˙ saved ) . Q ˙ saved = ε Q ˙ in (III) Here, effectiveness of the regenerator is ε . Write the formula to calculate amount of fuel saved by the regenerator for the company. Fuel saved = Q ˙ saved η (IV) Here, efficiency of the boiler is η . Write the formula to calculate amount of fuel saved by the regenerator for the company per year. Fuel saved = ( Fuel saved ) Δ t (V) Here, total time per annual is Δ t . Write the formula to calculate amount of money saved by the regenerator for the company per year. Money saved = ( Fuel saved ) ( Unit cost of fuel ) (VI) Write the expression for the entropy balance on the closed extended system. S ˙ in − S ˙ out + S ˙ gen = Δ S ˙ system Here, rate of entropy generation is S ˙ gen , rate of change in entropy of the extended system is Δ S ˙ system , rate of net entropy at inlet condition is S ˙ in and rate of net entropy at outlet condition is S ˙ out . For steady-flow system, the rate of change in entropy of the extended system is zero. Δ S ˙ system = 0 Then, the entropy balance on the closed extended system is, S ˙ in − S ˙ out + S ˙ gen = 0 S ˙ gen = S ˙ out − S ˙ in = S ˙ out = Q ˙ saved T 0 (VII) Write the expression to calculate entropy generation due to reduction ( S gen,reduction ) . S gen,reduction = ( Δ t ) S ˙ gen (VIII) Write the expression to calculate annual reduction in the exergy destruction ( X destroyed ) . X destroyed = T 0 S gen,reduction (IX) Here, dead state temperature is T 0 . Conclusion: The values of density and specific heat capacity of the milk are, ρ = 1 kg / m 3 c p = 3.79 kJ / kg ° C Substitute 1 kg / m 3 for ρ and 12 L / s for V ˙ in Equation (II). m ˙ = ( 1 kg / L ) ( 12 L / s ) = 12 kg / s Substitute 12 kg / s for m ˙ , 3.79 kJ / kg ° C for c p , 72 ° C for T 2 and 4 ° C for T 1 in Equation (I). Q ˙ in = ( 12 kg / s ) ( 3.79 kJ / kg ° C ) ( 72 ° C − 4 ° C ) = 3093 kJ / s Substitute 3093 kJ / s for Q ˙ in and 0

8th Edition

ISBN: 9780073398174

Author: Yunus A. Cengel Dr., Michael A. Boles

Publisher: McGraw-Hill Education

See similar textbooks

Videos

Question

Chapter 8.8, Problem 126RP

To determine

The amount of fuel saved by the regenerator for the company per year.

The amount of money saved by the regenerator for the company per year.

The rate of exergy destruction associated with the process.

Expert Solution & Answer

Want to see the full answer?

Check out a sample textbook solution

See solution

Chapter 8.8, Problem 125RP

Chapter 8.8, Problem 127RP

Students have asked these similar questions

FEA

Finite Element Analysis

an experimental research station is constructed on a concrete slab floor. The heat loss from the floor slab is significant, given the cold environment, and is measured to be 5 kW. The edges of the floor slab are insulated with a 60 mm thickness of cellular glass insulation. The width of this insulation at the floor slab is 0.9 m. To avoid excessive fuel consumption, the station air temperature is maintained at a slightly cool temperature of 18ºC. The station is constructed in a square shape, to keep the surface area to volume ratio low; the horizontal dimensions of the floor of the station are 20 m by 20 m. The number of occupants in the research station varies between 5 and 20, depending on the research workload.a) Determine the design outdoor temperature that was used in designing the research station.b) If the floor dimensions of the station are changed to 15 m by 25 m, would the design outdoor temperature that was used in designing the research station from part (a) change? If so,…

Chapter 8 Solutions

Thermodynamics: An Engineering Approach

Ch. 8.8 - What final state will maximize the work output of...Ch. 8.8 - Is the exergy of a system different in different...Ch. 8.8 - How does useful work differ from actual work? For...Ch. 8.8 - Prob. 4P Ch. 8.8 - Consider two geothermal wells whose energy...Ch. 8.8 - Consider two systems that are at the same pressure...Ch. 8.8 - Prob. 7P Ch. 8.8 - Does a power plant that has a higher thermal...Ch. 8.8 - Prob. 9P Ch. 8.8 - 8–10C Can a process for which the reversible work...

Knowledge Booster

Learn more about

Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, mechanical-engineering and related others by exploring similar questions and additional content below.

The amount of fuel saved by the regenerator for the company per year. The amount of money saved by the regenerator for the company per year. The rate of exergy destruction associated with the process.

Solution Summary: The author calculates the energy balance equation for a closed system for which the plate is taken as the system.

Videos

The amount of fuel saved by the regenerator for the company per year. The amount of money saved by the regenerator for the company per year. The rate of exergy destruction associated with the process.

Want to see the full answer?

Chapter 8 Solutions

The amount of fuel saved by the regenerator for the company per year.

The amount of money saved by the regenerator for the company per year.

The rate of exergy destruction associated with the process.