How to Calculate Boiler Efficiency Loss (Heat Loss) due to Evaporation of Water Formed From H2 Present in the Fuel?
This loss occurs because the hydrogen in the fuel burns to form water vapor, and this vapor exits with the flue gases, carrying away significant heat energy (sensible + latent). Since this heat is not recovered in a normal boiler (only in a condensing boiler), it escapes with the flue gases, resulting in a direct reduction in boiler efficiency.
Formula:
Heat Loss = 9 × H₂ × [584 + Cp × (Tf – Ta)] x 100 / GCV
Where:
9 kg = represents the fact that 1 kg of hydrogen (H₂) produces nearly 9 kg of water vapor (H₂O) through combustion.
H₂ = Hydrogen content in the fuel (as a decimal, e.g., 2.5% = 0.025)
584 kcal/kg = latent heat of vaporization of water at 0°C
Cp = Specific heat capacity of water vapor (approximately 0.45 kcal/kg·°C)
Tf = Flue gas temperature (°C)
Ta = Ambient temperature (°C)
GCV = Gross Calorific Value of fuel (kcal/kg)
Given Values (for example):
H₂ = 0.025
Cp = 0.45 kcal/kg·°C
Tf = 145°C
Ta = 40°C
GCV = 3900 kcal/kg
Calculation:
Heat Loss = 9 × H₂ × [584 + Cp × (Tf – Ta)] x 100 / GCV
= 9 x 0.025 × [584 + 0.45 × (145 – 40)] x 100 / 3900
= 0.225 × [584 + 0.45 × 105] x 100 / 3900
= 0.225 × [584 + 47.25] x 100 / 3900
= 0.225 × 631.25 x 100 / 3900
= 14203 / 3900
= 3.64%
Final Answer:
The boiler efficiency loss (heat loss) due to evaporation of water formed from H₂ present in the fuel is approximately 3.64%.
Frequently Asked Questions
1. What is sensible heat?
Sensible heat is the heat energy that causes a change in temperature of a substance without changing its state.
2. What is latent heat?
Latent heat is the energy required to change the state of a substance (like from liquid to gas or solid to liquid) without changing its temperature.
3. How does latent heat affect boiler efficiency?
In a boiler, latent heat is lost when water vapor in the flue gases carries away energy that isn’t recovered, reducing efficiency.
4. What is the difference between sensible heat and latent heat in boilers?
Sensible heat affects the temperature of the flue gases, while latent heat is related to the phase change (evaporation/condensation) and is lost if not recovered.
5. How can boiler efficiency be improved?
Boiler efficiency can be improved by using condensing boilers that recover latent heat from the flue gases, or by optimizing combustion and reducing heat losses.
Need Help?
+92-3332169498