How do you calculate LHV to HHV?
Under this formula, the relationship between the lower heating value of a fuel and the higher heating value of that fuel is: LHV = HHV – 10.55(W + 9H) Where: LHV = lower heating value of fuel in Btu/lb, HHV = higher heating value of fuel in Btu/lb, W = Weight % of moisture in fuel, and H = Weight % of hydrogen in fuel.
What is HHV in energy?
The lower heating value (LHV) or higher heating value (HHV) of a gas is an important consideration when selecting a gas engine or CHP plant. The total amount of heat liberated during the combustion of a unit of fuel, the HHV or HCV, includes the latent heat stored in the vapourised water.
What is the significance of knowing both the higher and lower heating value?
It is so important to know HHV and LHV for any hydrocarbon fuel. The importance of HHV and LHV comes from whether we permit to have water liquid in the product of combustion or not. If not, then part of the liberated heat is used to evaporate the liquid, and the rest is considered as a useful heat.
Why is the difference between the higher and lower heating value of a fuel such as natural gas important in determining the increased boiler efficiency?
The fuel’s Lower Heating Value (LHV) is the same as HHV, excluding the latent heat of vaporization of water. Thus, we can conclude that the difference between the HHV and the LHV of a fuel is latent heat of vaporization of water. This is why it is important to release the latent heat of vaporization.
What is HHV used for?
The higher heating value (HHV; gross energy, upper heating value, gross calorific value GCV, or higher calorific value; HCV) indicates the upper limit of the available thermal energy produced by a complete combustion of fuel. It is measured as a unit of energy per unit mass or volume of substance.
How is LHV of coal different from HHV of coal?
The numerical difference between LHV and HHV depends on the fuel. The difference is smallest for coal (where LHV is roughly 4 percent less than HHV) and greatest for natural gas (where LHV is about 10 percent lower).
Is natural gas HHV or LHV?
A rule of thumb for natural gas is HHV = LHV x 1.11.
How do you calculate LHV of biomass?
To calculate the LHV you must subtract the heat of vaporization of H2O from the HHV. Long ago the heat of vaporization of water was 550 cal/g or (X the Mole wt of 18) 9900 cal/mole. Now it is (multiplying by 4.184 J/cal) 41,422J/mole or 41.4 kJ/mole (thanks to Mr. Metric).
What is the difference between HHV and LHV?
The key difference between HHV and LHV is that HHV can be determined by bringing all the products of combustion back to the original pre-combustion temperature while allowing any produced vapour to condense. Meanwhile, LHV can be determined by subtracting the heat of vaporization of water from the higher heating value.
What is the ratio of HHV to LHV for fuel?
Fuel suppliers will usually quote the HHV and it will be this measure that will be used when kWh unit charges are applied for the fuel. In the case of natural gas the ratio of HHV to LHV is approximately 1.108:1.
What are the typical HHV and LHV efficienci of gas boilers?
Table 1 – Typical HHV and LHV efficienci % HHV % LHV Gas boiler 80 89 Gas engine (2 MWe) 38 42 Gas turbine (5 MWe) 28 31
What is lower heat value (LHV)?
Lower Heat Value:LHV uses only some of the heat contained in the wood when calculating efficiency. This is sometimes called the “Net Value” or the “Lower Value”