Taking into account the "Second Law of thermodynaics", what is the maximum percentage of heat at 700 C that can be converted into electricity if the waste heat was produced as steam at 100 C?
The Second Law of Thermodynamics states that in any energy conversion process, the amount of usable energy (or work) that can be obtained is always less than the total energy input. In other words, it is impossible to convert all of the heat into useful work.
To determine the maximum percentage of heat at 700°C that can be converted into electricity, we can use the concept of Carnot efficiency. The Carnot efficiency is the maximum possible efficiency of an ideal heat engine operating between two temperatures.
In this case, the waste heat is produced at 700°C, and the steam temperature is 100°C. Therefore, we can calculate the Carnot efficiency using the formula:
Carnot efficiency = 1 - (Tc / Th)
Where Tc is the absolute temperature of the cold reservoir (in Kelvin) and Th is the absolute temperature of the hot reservoir (in Kelvin).
Converting the temperatures to Kelvin:
Tc = 100°C + 273.15 = 373.15 K
Th = 700°C + 273.15 = 973.15 K
Now we can substitute these values into the formula:
Carnot efficiency = 1 - (373.15 / 973.15)
Carnot efficiency = 0.617 or 61.7%
Therefore, the maximum percentage of heat at 700°C that can be converted into electricity, given that the waste heat is produced as steam at 100°C, is approximately 61.7%.