 Ch 5. Second Law of Thermodynamics Multimedia Engineering Thermodynamics Heat Engine The SecondLaw CarnotCycle Carnot HeatEngine CarnotRefrigerator
 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 SOLUTION

Three designs for a power plant using the geothermal energy are proposed by a company. Use the Carnot principles to determine which design is possible. Carnot Principles

Power plant receives heat from a heat source (the hot spring), output net work, and rejects heat to a heat sink (the ambient air). Hence, it is a heat engine. All heat engines in practice are irreversible.

The Carnot principles state that the efficiency of an irreversible heat engine is always less than the efficiency of a reversible one operating between the same two reservoirs. The thermal efficiency of a Carnot heat engine working between 140 oC and 30 oC is 26.6%.

 Team A B C efficiency 18.0% < 26.6% 26.6% = 26.6% 28.0% > 26.6% Possibility possible impossible impossible