RWTH-EBC / AixLib

A Modelica model library for building performance simulations
https://ebc-tools.eonerc.rwth-aachen.de/aixlib
178 stars 82 forks source link

Modular equation-based model of Air Handling Units #834

Open KremerMartin opened 4 years ago

KremerMartin commented 4 years ago

What is the problem?

Currently we are using the AHU model provided by @PMehrfeld to calculate the energy consumption of the air handling unit in building simulation. This model is fixed in its configuration. We want to resolve this restriction, by providing an AHU model consisting of sub-models for the AHU components.

How do we want to solve it? Describe the solution you'd like

We will provide one model each for every component in the air handling unit. By combining these models one will get an AHU configured the way it should be. In a next step we will think of a possibility to provide a configurable AHU model to the user via parameter tab.

Every component will be adressable in the way the old model adresses the different fuctions, by using set-Value conditions for the outlet temperature/humidity. Moreover a possibility to use heatPorts and mass flow rates will be provided to use the components as well for some control tests.

Closes #310 .

PMehrfeld commented 4 years ago

@KremerMartin : Since #310 is closed, does it mean this issue can also be closed?

KremerMartin commented 4 years ago

@PMehrfeld No. The intention was to close the old issue and provide more details here. The developed AHU model (until now developed in GitLab) will be transferred into a branch related to this issue on the next hackday.

KremerMartin commented 4 years ago

Added first version by commit 8bdd32b73519e23adfc9b0be678b662f32dbc14a

YingXC commented 4 years ago

@KremerMartin What is the current status? Maybe an issue for the hackday?

KremerMartin commented 4 years ago

@XucYin As I see it, there is no progress on this issue since the hackday at the beginning of this year. @KFinkbeiner Am I right with this assumption or have you provided some progress on the model by now? Maybe I find some time during the hackday to make some progress.

YingXC commented 4 years ago

For the next steps I would suggest:

DaJansenGit commented 3 years ago

any new developments here? maybe something for hackday tomorrow @martinkremer ?

YingXC commented 3 years ago

Following results are recorded when comparing the modular AHU model with the AixLib.Airflow.AirHandlingUnit.AHU for a stationary heating case with the heat recovery system deactivated (efficiency both set to 0). With various outdoor air temperature, the result deviations are small but the relative deviations are not linearly proportional to the temperature difference. grafik

grafik

One reason is the different specific heat capacity of the dry air used in the two models. When using the same value (1005 J/kg/K), smaller deviations are to be observed. @KremerMartin found another reason: At lower outdoor temperature inputs, the relative deviations increase because the existing model AixLib.Airflow.AirHandlingUnit.AHU decreases the inputed absolute humidity when the relative humidity exceeds 100%, which is physically correct but not directly visible for users. grafik

FelixStege commented 1 year ago

Any updates here? Maybe this is something for the upcoming hackday?

KremerMartin commented 1 year ago

Update: I cleaned the branch, deleted some old obsolete models and model parts. Open ToDos:

Since the old air handling unit model does not contain the functionalities for heat recovery only or steam humidification no verification will be possible for these cases.

KremerMartin commented 1 year ago

The current differences in the two ahu models: grafik

KremerMartin commented 1 year ago

Dehumdification results get closer, if the bypass-factor dehumidification of old ahu is set to zero. This is striking. Needs to be checked if old model is correctly implemented.

KremerMartin commented 4 months ago

Update on the progress: Since results of the AixLib.Airflow.AirHandlingUnit.AHU are in many operation points not quite reliable, a comparison as planned seems not sensible. Therefore the new models shall be compared to analogue models in the Fluid package. First test cases for validation of the sub-components have been implemented, showing good agreement. Open ToDos: