Understanding Entropy: Examples of Unavailable Energy in Everyday Life

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SUMMARY

Entropy quantifies the amount of energy that is unavailable to perform work, a crucial concept in thermodynamics. For instance, water at room temperature (20°C) possesses energy but cannot heat a mug of coffee at 30°C without an external energy source, such as a heat pump. The discussion emphasizes the distinction between available and unavailable energy fractions, highlighting practical implications in everyday scenarios. For further understanding, the Wikipedia article on exergy provides comprehensive theoretical and practical insights.

PREREQUISITES
  • Basic understanding of thermodynamics principles
  • Familiarity with the concept of exergy
  • Knowledge of heat transfer mechanisms
  • Awareness of energy states (available vs. unavailable)
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  • Study the principles of thermodynamics in detail
  • Explore the concept of exergy and its applications
  • Learn about heat pump technology and its energy efficiency
  • Investigate real-world examples of energy conversion and entropy
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Students of physics, engineers in energy systems, and anyone interested in understanding thermodynamic principles and their applications in everyday life.

trungdien
From what I have heard, entropy is the amount of energy that is unavailable to do work. What exactly does it mean by "unavailable energy", and can someone give some examples of energy being unavailable to do work in real life?
 
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Water at room temperature (20C) contains energy (because it's not at absolute zero) but that energy can't be used to heat up a mug of coffee already at 30C (You could do it using a heat pump but that needs an external source of energy).
 
:welcome:

You can talk about the unavailable or the available fractions of total energy.

See the Wikipedia article https://en.wikipedia.org/wiki/Exergy
It explains both theory and practical examples.
 

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