Shortcomings of the First-Law Efficiency

It would have been observed that the efficiency used in non-cyclic process is depending just on the First Law of Thermodynamics; no Second Law implications are thought. In common, the First Law efficiency might be explained as the ratio of energy transfer of the preferred type attained by the device to the energy input to the device. The First Law efficiency has the shortcomings as follows:

• Its maximum value might be greater than, equivalent to, or less than 1 (based on the device and on temperatures).

• It can’t be readily generalized to complicated systems in which the preferred output is a combination of work and heat (i.e., as in cogeneration systems). This is since, in the eyes of the first law, work and heat are equal, quantitatively and qualitatively.

• It totally ignores second law implications that play the vital role in governing energy resource conservation and utilization.

• Not only does it give appropriate guidance for energy resource conservation, though also it leads to incorrect conclusions.

For illustration, the second-law analysis of a power plant reveals two significant points that the traditional first-law analysis fails to illustrate up:

• Whereas the condenser energy loss emerges to be an important proportion of the energy input to the power plant, its energy equal is quite unimportant, and therefore of small economic value.

• Irreversibility or destruction of energy caused by combustion, heat transfer and fluid flow phenomenon constitute an important proportion of the energy input to the system; such effects, though, cannot even be exposed by the first-law analysis.