syngas, LHV/NCV, HHV/GCV, heating value,
or simply what heating rate am I going to use?
The numerical difference between the two is the latent heat of condensation of the water vapour in the combustion exhaust gas, which in turn depends on the hydrogen content of the fuel being burned.The difference is minimal for coal, significant for natural gas and largest for pure hydrogen fuel. So you have to do the conversion calculation for the specific case.
Have a look at below attached link:
https://www.iconceptpress.com/download/paper/12012321442701.pdf
sir Obid Tursunov. if i'm going to calculate for calorific value of syngas to be used in the engine. is it LHV or HHV? cause some study uses LHV and Some uses HHV?.. im really confuse what to calculate
As already pointed out, the diference has to do with the water content. For a coal, you can use the following equation: LHV=HHV - 8.94 H 1050, where HV is in Btu/lb and H=total fraction of hydrogen.
The combustion products of a normal engine are all gaseous, so you need the LHV.
As explained before, the difference relays over the state of the water generated by combustion: as the name says, HHV considers that water leaves in liquid state and LHV consider gas state. Since just after the combustion you have water vapour, consider LHV!
What are you using the HHV or LHV for? If you are using it as a basis for stating the efficiency of the engine you may use either but should state which you are using as the basis of your efficiency calculation. Without qualification you should use the HHV as this convention returns the reaction products to the standard thermochemical convention. If want to use the energy in calculation of the actual performance of an engine, neither is correct. In that case you need to calculate the energy release from the actual input conditions, which may be close to standard conditions (25C, 1 atm), to the actual final combustions conditions, which certainly are not anywhere near standard conditions.
The difference between HHV and LHV is the amount of thermal energy is being utilized to translate the water from liquid state to vapor state in the total synthesis gas heat value. It means this energy need to be discounted from the total heating value of the synthesis gas. Because this energy will not be available for the desired duty. it is always appropriate to use LHV to represent the synthesis gas heating value in the general applications.
The difference between HHV and LHV is the amount of thermal energy is being utilized to translate the water from liquid state to vapor state in the total synthesis gas heat value. It means this energy need to be discounted from the total heating value of the synthesis gas. Because this energy will not be available for the desired duty. it is always appropriate to use LHV to represent the synthesis gas heating value in the general applications.
The difference between HHV and LHV is the amount of thermal energy is being utilized to translate the water from liquid state to vapor state in the total synthesis gas heat value. It means this energy need to be discounted from the total heating value of the synthesis gas. Because this energy will not be available for the desired duty. it is always appropriate to use LHV to represent the synthesis gas heating value in the general applications.
The difference between HHV and LHV is the amount of thermal energy is being utilized to translate the water from liquid state to vapor state in the total synthesis gas heat value. It means this energy need to be discounted from the total heating value of the synthesis gas. Because this energy will not be available for the desired duty. it is always appropriate to use LHV to represent the synthesis gas heating value in the general applications.
When internal-combustion engines or boilers with no secondary condenser are designed, the appropriate fuel value to use in the design process is the LHV, which assumes that the water vapor generated when the fuel is burned goes out in the exhaust stream. When advanced combustion units having secondary or tertiary condensers are designed, the appropriate fuel value to use in the design process is the HHV. In summary: HHV-LHV= latent heat of vaporization
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