Organic Rankine Cycle Power Calculator
Use our online calculator to estimate the electric and thermal power that can be retrieved from your heat source using an ORC Turbogenerator. You will get both the theoretical and the real cycle efficiency, taking into account real world factors such as mechanical losses, heat losses, etc.
Please keep in mind that these are only estimates. They can be useful to get a rough idea, but in reality things can differ significantly from case to case. To have a more precise evaluation please contact our sales engineers. They will be happy to conduct a deeper analysis on your specific case.
Start the calculation.
Step 1 of 3
Which kind of heat source do you have?
Step 2 of 3
Drag to select inlet temperature before heat exchange (on the right)
and outlet temperature after heat exchange (on the left)
Step 2 of 3
How much biomass is available to be burnt?
Do you know the Low Heating value of your Biomass?
Do you know the percentage of water content of your Biomass?
The low heating value is evaluated assuming a higher heating value equal to 5 kWh/kg.
For this simulation we will assume a default Low Heating Value of 2.5 kWh/Kg
Step 3 of 3
Choose a cold source for the heat produced by your plant:
Drag to select the inlet temperature of the cooling fluid before heat exchange (on the left)
and the outlet temperature of the cooling fluid after heat exchange (on the right)
Note: if you have selected air (no thermal use) as the cooling fluid, we suggest you use the annual mean temperature of the source site as the inlet temperature and the annual mean temperature+10-12°C (or equivalent) as outlet temperature
Theoretical Cycle Results:
Assumptions ΔT constant for finite heat exchange area:
* ΔTpreheater + evaporator = 15 K
* ΔTcondenser = 10 K
For biomass, Lorenz Cycle efficiency is calculated with the thermal oil inlet/outlet temperature
Real efficiency to Lorenz efficiency ratio (finite exchange area)
Thermal Power - temperature diagram
Yellow: Heat Source, thermal oil in case of Biomass
Red: working fluid, hot side
Green: working fluid, cold side
Blue: cooling fluid
AND NOW?You can restart the calculation to input different values, or you can contact our sales engineers to have a more specific evaluation of your case.
To know more about this calculation, you can read our calculation procedure
Lorenz cycle efficiency
In the same way as Carnot cycle is the maximum efficiency cycle that can be retrieved from a perfect gas between two constant temperature sources, the Lorenz cycle is the one that can get the maximum efficiency from a cycle between two variable temperature sources with constant heat capacity.
The Lorenz cycle is made of the four following transformations:
Efficiency of Lorenz cycle:
where Tlm,cold and Tlm,hot are the log mean temperatures of the cold and the hot sources respectively.
If the thermal exchange areas are finite, as in the real case, the temperature of the working fluid can not match exactly the temperatures of the heating and cooling sources. Through the assumption of constant temperature differences between the working fluid and the sources fluids, it is possible to calculate a new Lorenz cycle efficiency:
where T*cold = Tcold + ΔTcondenser and T*hot = Thot - ΔT preheater + evaporator
Real cycle efficiency
The real cycle efficiency is lower than the corresponding Lorenz cycle, since:
It is possible to take into account all these aspects by means of a global factor X lower than 1. Real cycle efficiency can be defined as:
η real cycle = X * η Lorenz, finite exchange area
It is possible to calculate the mechanical power as the product of the thermal power from the heat source, which is known, by the real cycle efficiency.
The electric power can be derived from the mechanical power by multiplying it by the generator efficiency.
Since it can be assumed that compression and expansion are adiabatic, the thermal power to the condenser can be calculated by subtracting the mechanical power from the thermal power given by the heat source.
The thermal power to the condenser is available for thermal applications such as drying (sawmills, pellet factories), pre-heating (MDF industries), district heating networks, refrigeration.