Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
Hey akey,
I believe the nominal heat flow rate is the nominal capacity of the radiator at nominal conditions, i.e. Power output under nominal mass flow rate and nominal deltaT conditions for a fixed ambient air temperature.
For instance, the rated radiator capacity is provided by manufactures generally for an inlet water temperature of 75ºC, outlet temperature of 65ºC, for an ambient room temperature of 20ºC (but also for 70ºC/50ºC/20ºC and 55ºC/45ºC/20ºC) and for a given water mass flow rate. Those are rated conditions. However, during dynamic simulation, those conditions are not fixed and the "real" instantaneous radiator power output will vary as those conditions also change, following the radiator characteristic equation.
You can find an example of this data on pages 3,4 and 5 of a radiator catalog data here: http://www.stelrad.eu/stelrad_nl/wp-content/uploads/STR-TD-EN.pdf
The nominal heat flow rate is the rated capacity of the radiator as provided by the manufacturer under the test conditions defined by EN442. If you are not working with specific equipment, It can also be the peak heating demand of a room which would be supplied by the radiator. The same applies to heat exchanger models.
You can also find documentation on this here:
http://simulationresearch.lbl.gov/modelica/releases/latest/help/Buildings.html
http://simulationresearch.lbl.gov/modelica/releases/latest/help/Buildings_Fluid_HeatExchangers_Radiators.html#Buildings.Fluid.HeatExchangers.Radiators.RadiatorEN442_2
Sorry for the bad English, and i hope that I was clear enough. Good luck for your project.
| | 2 | No.2 Revision |
Hey akey,
I believe the nominal heat flow rate is the nominal capacity of the radiator at nominal conditions, i.e. Power output under nominal mass flow rate and nominal deltaT conditions for a fixed ambient air temperature.
For instance, the rated radiator capacity is provided by manufactures generally for an inlet water temperature of 75ºC, outlet temperature of 65ºC, for an ambient room temperature of 20ºC (but also for 70ºC/50ºC/20ºC and 55ºC/45ºC/20ºC) and for a given water mass flow rate. Those are rated conditions. However, during dynamic simulation, those conditions are not fixed and the "real" instantaneous radiator power output will vary as those conditions also change, following the radiator characteristic equation.
You can find an example of this data on pages 3,4 and 5 of a radiator catalog data here: http://www.stelrad.eu/stelrad_nl/wp-content/uploads/STR-TD-EN.pdf
The nominal heat flow rate is the rated capacity of the radiator as provided by the manufacturer under the test conditions defined by EN442. If you are not working with specific equipment, It can also be the peak heating demand of a room which would be supplied by the radiator. The same applies to heat exchanger models.
You can also find documentation on this here:
http://simulationresearch.lbl.gov/modelica/releases/latest/help/Buildings.html
http://simulationresearch.lbl.gov/modelica/releases/latest/help/Buildings_Fluid_HeatExchangers_Radiators.html#Buildings.Fluid.HeatExchangers.Radiators.RadiatorEN442_2
Sorry for the bad English, and i I hope that I was clear enough. Good luck for your project.
