CHP (Combined Heat & Power)
- Dennis De Beuckeleer
Combined heat and power, sometimes called cogeneration, are systems which provide both electricity and heating simultaneously. Traditional power plants release the remaining heat to the environment while these systems recover the produced heat. Therefore, cogeneration systems have higher efficiency compared to these traditional systems which provide electricity and heat separately.
The Hysopt software contains 2 different CHPs, namely:
 Combined heat and power |  Boiler with Stirling engine |
We will explain these two in more depth down below.
Combined Heat & Power
The combined heat & power base circuit is shown above and has three nodes for connections. 1 node is for piping and the 2 others are for control lines.
These control lines require the following inputs:
Name | Explanation | Range |
|---|---|---|
Activation signal | This signal says if the base circuit has to be put on or off. | 0 or 1 |
Valve position | This signal gives the required modulation of the CHP. The CHP can be modulated between 0% (=off) or 100% (=fully on). | This can be a value between 0 and 1 |
For more information about the controller, check the CHP - Basic Control page.
The base circuit has the following parameter window when the simulation layer is visible:
The table below contains an explanation of what all these parameters* mean:
Parameter name | Explanation | Range |
|---|---|---|
Nominal thermal power | This value defines how much thermal power the CHP can provide to the heating system. | Hysopt supports a range from 0-100 MW. |
Reference return temperature | This value has an impact on the thermal efficiency of the CHP. A similar capacity for different reference return shows differences between units | Hysopt supports a range from -5-200 °C. |
Electrical efficiency table | Contains the relation of the electrical load factor to the electrical efficiency. | See below for more information about this table. |
Thermal efficiency table | Contains the relation of the electrical load factor and the return temperature to the thermal efficiency. | See below for more information about this table. |
Water heat capacitance | This value defines how much heat has to be provided to increase the temperature of the water content by 1 Kelvin. | Only positive values. |
KV value | Expresses the amount of flow for a pressure drop of 1 bar. | Only positive values. |
* The environment temperature is only used to calculate the heat losses of the CHP. If you leave this empty and the BC is not in a zone, the external temperature is used.
Electrical efficiency table
This table needs to contain 2 columns:
Name | Explanation |
|---|---|
Electrical load factor | This value represents the modulation signal that the CHP receives. |
Electrical efficiency | Indicates the electrical efficiency that the CHP has for that electrical load factor. |
The default electrical efficiency table looks like the following picture.
Thermal efficiency table
This table needs to contain 3 columns:
Name | Explanation |
|---|---|
Electrical load factor | This value represents the modulation signal that the CHP receives. |
Return temperature | Indicates the return temperature of the CHP. |
Electrical efficiency | Indicates the thermal efficiency that the CHP has for that electrical load factor and return temperature. |
The default thermal efficiency table looks like the following picture.
The process of changing the efficieny tables is similar as those in the boiler BC. A step-by-step guide on changing the efficiency lookup table, can be found here: Changing boiler efficiency (with templates) .
Boiler with Stirling engine
A boiler with a Stirling engine is a small CHP that is mostly used for residential installations. It is used most of the time in combination with a normal boiler.
The Stirling engine base circuit is shown above and has two nodes for connections. 1 node is for piping and the other one is for the control line.
The control line requires the following input:
Name | Explanation | Range |
|---|---|---|
Activation signal | This signal says if the base circuit has to be put on or off. | 0 or 1 |
The Stirling engine with boiler base circuit has the following parameter window when the simulation layer is visible:
The table below contains an explanation of what all these parameters* mean:
Parameter name | Explanation | Range |
|---|---|---|
Water content heat capacity | This value defines how much heat has to be provided to increase the temperature of the water content by 1 Kelvin. | Only positive values. |
Nominal power | This value defines how much thermal power the CHP can provide to the heating system. | Hysopt supports a range from 0-100 MW. |
KV value | Expresses the amount of flow for a pressure drop of 1 bar. | Only positive values. |
* The environment temperature is only used to calculate the heat losses of the CHP. If you leave this empty and the BC is not in a zone, the external temperature is used.
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