Example: An electric resistance heater has ( \eta_I \approx 100% ) (all electricity becomes heat). But its ( \eta_II ) is tiny (high-quality electrical exergy degraded to low-quality room heat). A heat pump, however, can have ( \eta_I > 100% ) and much higher ( \eta_II ). Nag forces the student to think: Do we want to conserve quantity (First Law) or quality (Second Law)? For a sustainable future, the answer is quality.
The science behind cooling systems and heat pumps. basic and applied thermodynamics pk nag
Basic thermodynamics taught us that energy is conserved (First Law). Applied thermodynamics teaches us that energy is not all equal. A joule of heat at 1000 K can do more work than a joule of heat at 400 K. Exergy (( \Phi )) is the maximum useful work obtainable from a system as it comes to equilibrium with the environment. Example: An electric resistance heater has ( \eta_I
Defining temperature and thermal equilibrium. Nag forces the student to think: Do we