Thermodynamics and Exergy Analysis in Energy Systems

Reconciliation of Mass and Energy Balance

The determination of the highest reliable evaluation of searching values under the assumed criterion of quality is essential. The most well-known and effective method employed for improving the conformity of condition equations is the least squares adjustment method.

Exergy as a Measure of Energy Carriers

Different kinds of energy carriers are characterized by different quality. The ability to perform work can be accepted as a measure of energy quality. The dead-state (reference level) is determined by the parameters of the environment.

The higher the difference between the thermal parameters and composition of the energy carrier and the environment, the higher the quality of the considered energy carrier.

Comparing Energy Efficiency in Different Systems

The main problem is that comparing the efficiency of different energy systems using only the First Law of Thermodynamics is highly misleading. Consider the following examples:

• Heat Pumps: Show an "impossible" 300% efficiency because they extract free heat from the environment instead of creating energy.
• Solar Panels (PV): Are left at a seemingly "poor" 15%, ignoring that their input source (the Sun) is free, clean, and unlimited.
• Power Plants vs. Boilers: Charts often mix technologies producing high-quality electricity (42%) with systems generating low-quality heat (96%).

In conclusion, this quantitative criterion is flawed for comparing such diverse systems, as it fails to evaluate energy quality or the nature of the resource used.

Exergy Balance and Component Interpretation

• Endogenous (Immediate) Exergy Destruction: Independent of remaining components; this is the exergy destruction occurring within the k-th component operating with its current efficiency when all other components operate in an ideal way.
• Exogenous (Induced) Exergy Destruction: The part of exergy destruction within the k-th component that is caused by the irreversibilities occurring in the remaining components.

The Fuel-Product Table

The Fuel–Product (F-P) Table is a systematic matrix that tracks how energy or exergy (useful energy) enters, transforms, and leaves a system. This method defines exactly what each individual component (1, 2, …, n) consumes as its resource (Fuel) and what it generates as its useful output (Product).

It is a critical diagnostic tool used to identify and quantify malfunctions and dysfunctions within a system.