Example of a Simple Analysis

The thermodynamic efficiency r of the process is then defined as the ratio of the available work leaving the process and the available work entering the 

Materials Available Work (kj/mol) Raw Materials Available Work (kj/mol) 

The analysis requires the calculation of three exergy flow rates, at 0°C, 50°C, and 100°C. As no heat or work is transferred between the considered system and its environment, the first law, Equation 6.1, yields that the overall enthalpy change is zero  

Multiplying Equation 6.21 with H0, the enthalpy of liquid water at T0, and subtracting the result from Equation 6.20, we obtain 

As the change of enthalpy with pressure under these conditions can be neglected and, to some approximation, the specific heat of liquid water can be considered constant in this example, we can write 

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