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And even more... Subscribed users have access to the full set of 19 calculators available as Java™ Web start application or download Windows™ 64bit application.

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- q - Volume flow rate
- Fuel flow rate in terms of units of volume per unit of time
- ṁ - Mass flow rate
- Fuel flow rate in terms of units of mass per unit of time
- P - Power - heat power
- Energy needed for combustion in unit of time
- P1 - Actual power
- Useful heat energy - power after reduction due to energy losses in energy conversion from combustion heat to, for example, hot water heat energy
- LHV_V - Heat value
- Heat energy created during combustion in units of volume
- LHV_G - Heat value
- Heat energy created during combustion in units of mass
- ρ - Density of fuel
- This value is only required if you want to calculate flow rate or heat power in different units (as per unit of mass or volume).
- η - Efficiency
- Energy losses coefficient ratio between actual heat power and combustion heat power that represents efficiency of energy conversion.

Efficiency coefficient is used to represent losses in energy conversion from
combustion energy to energy available for end use like hot water heat energy from boiler.
If you have specified hot water heat energy demand P_{1} and if you know boiler efficiency - η,
calculator gives you required actual heat power from combustion
like P_{1}/ η. You can select not to use this feature by selecting η in Omit section.

- Select value to calculate. You should input values for not selected one.
- P
- heat power calculation
- ṁ
- fuel flow rate calculation
- LHV_V/LHV_G
- fuel heat value calculation

- Select value to input. Not selected one will be calculated.
- P
- heat power
- P
_{1} - actual heat power

- Select value to input. Not selected one will be calculated.
- q
- volume flow rate
- ṁ
- mass flow rate

- Select value to input. Not selected one will be calculated.
- LHV_V
- lower heat value in terms of volume
- LHV_G
- lower heat value in terms of mass

- Use η in calculation
- for calculation of actual energy after energy losses in combustion process
- Use ρ in calculation
- for conversion between mass and volume