Ch 6. Entropy th Multimedia Engineering Thermodynamics Entropy Tds Relations EntropyChange IsentropicProcess IsentropicEfficiency EntropyBalance (1) EntropyBalance (2) ReversibleWork
 Chapter 1. Basics 2. Pure Substances 3. First Law 4. Energy Analysis 5. Second Law 6. Entropy 7. Exergy Analysis 8. Gas Power Cyc 9. Brayton Cycle 10. Rankine Cycle Appendix Basic Math Units Thermo Tables Search eBooks Dynamics Statics Mechanics Fluids Thermodynamics Math Author(s): Meirong Huang Kurt Gramoll ©Kurt Gramoll

 THERMODYNAMICS - CASE STUDY Introduction Problem Description Click to View Movie (62 kB) A manufacturing facility has a production line to fill its air conditioning systems with liquid refrigerant-134a. A throttling valve is used to reduce the pressure of refrigerant-134a before filling. If the throttling valve is replaced by a turbine, which can generate power, how mach can this turbine save in electricity cost? What is known: Refrigerant-134a is at 0.3 MPa after throttling. Refrigerant-134a is at -4oC and 1 MPa before throttling. The mass flow rate of refrigerant-134a is 200 kg/s. Question Determine the maximum power that the turbine can produce. If the turbine operates 8,760 hr/yr, and electricity costs the facility \$0.08/kWh, how much can the turbine save per year? Approach Take the turbine as a system. This is a control volume. Assume the turbine is adiabatic and the process is reversible. That gives, S1 = S2