This is my code, I searched on the internet but can not find any solution. While compiling this error message shows up:

Package inputenc Error: Unicode char fi (U+FB01)(inputenc) not set up for use with LaTeX. ...would achieve the highest second law effi

    Organic rankine cycle has been a topic of highest interest in recent years. Different types of working fluid and design parameters are considered for the augmentation of performance from an ORC based cycle [9–18] . Out of these numerical and experimental analysis, some recent findings are discussed in this section of literature. Meng Zhao et. al. [19] studied the effects of the ORC Operating Conditions on the Engine Performance for an Engine-ORC Combined System. From the conclusion of this study it was found that engine backpressure increases with the decrease of the pump speed and the expander speed. The maximum engine power output increment at the engine speed of 1500 r$/$min and 2100 r$/$min is 5.47 kW and 7.07 kW respectively. The backpressure increment of the engine with ORC system increases with the increasing of cooling water inlet temperature. From the study of Wenqiang Sun et. al. [20] we can see the exergy efficiency analysis of ORC (Organic Rankine Cycle) and ORC-based combined cycles driven by low-temperature waste heat From the conclusion of his study, the exergy efficiency of both systems decreases with the increase of the evaporation temperature of the ORC. The net power output, the refrigerating capacity and the resultant exergy efficiency of the uncoupled ORC-ARC are all higher than those of the ORC-ERC for the evaporation temperature of the basic ORC $>\SI{153}{\degreeCelsius}$, in the investigated application. Li et. al. [21] showed in his study of a cascade organic Rankine cycle power generation system using hybrid solar energy and liquefied natural gas that an equivalent efficiency of 5.99 $\%$ is achieved with isopentane$/$R125 and ETC and the hybrid system has a faster return on solar power investment than a solar ORC. Landelle et. al. [22] explained based on his experimental database report of ORC design and performance comparison, the closed heat source (e.g. thermal solar) case would achieve the highest second law efficiency using a subcritical regenerative ORC with R245fa as working fluid, while the open source case would achieve the highest exergetic recovery efficiency using a transcritical ORC with R404a. Desai et. al. [23] showed in the study of Thermo-economic comparisons between solar steam Rankine and organic Rankine cycles that the optimum regions of the selection diagrams remain almost unchanged with the change in working fluid, solar collector field cost, cycle efficiency, power block cost, and location of the plant. However, the cost of energy for a linear Fresnel reflector based plant with steam Rankine cycle ($\sim$ 0.422 $\$$\textbackslash kW h) is much higher than parabolic trough collector ~ based plant with steam Rankine cycle ($\sim$ 0.353 $ \$ $\textbackslash kW h).

Can anyone help ? Thanks in Advance :)

  • 1
    Off - topic: Use siunitx for the display of the units
    – user31729
    Aug 25, 2017 at 13:32
  • It looks like you're using an editor that hard-codes the ligature glphs ("fi") and ("fl"). If that's the case, then do instruct the software not to use such hard-coding. At any rate, you should proceed by replacing the ligated glyphs with the appropriate composite letter combinations.
    – Mico
    Aug 25, 2017 at 13:39
  • Thank you for your comment. But I copied my paragraph in normal notepad (the one in windows) and then copy pasted it again in the section. but still the problem shows. can you edit my code so that this error doesn't show up? Aug 25, 2017 at 13:50

1 Answer 1


For example in the word "efficiency" the letters f and i are joined into a single symbol - a ligature. There are more cases of this in your text (f and l of "fluid", ...).

Normally LaTeX creates ligatures by itself. It seems your editor did this and encoded it as a Unicode character inputenc does not understand.

Either you go through your document cases by case, or you or you help LaTeX to understand that character.

  • @Voigt Thank you for your comment. But I copied my paragraph in normal notepad (the one in windows) and then copy pasted it again in the section. but still the problem shows. can you edit my code so that this error doesn't show up? Aug 25, 2017 at 14:06
  • 1
    The ligature of f and i is ONE single character in Unicode. It does not appear every time in your text there an i follows an f, but for example in "achieve the highest second law efficiency". If you put the cursor left of the f and tipe "arrow right" once (!), the cursor ends up after the i. Modern versions of notepad work with unicode encoding so copying the text back and forth does not change a thing - perfectly valid unicode, yet inputenc does not like it. Aug 25, 2017 at 14:40
  • 1
    However you can copy the ligature and use the search and replace function of notepad to change it into two characters. You have to do that with the ligature of f and l as in "linear Fresnel reflector", of f and i as above. This does not solve the underlying problem. As @Mico pointed out: you might have to change the configuration of the editor which did that in the first place. If this is not possible, follow the links in my answer for a way to make inputenc aware of that. Aug 25, 2017 at 14:40

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