Problem with liquid temperature readings in SimScape
5 views (last 30 days)
Show older comments
Hello,
I am trying to understand how the physics of the thermal liquid library works. I have a specific case that I am trying to simulate but SimScape does not appear to be reproducing the physics that I would expect.
Consider the following simple example shown below. If you heat up a closed loop of liquid that is circulating, I would expect that the temperature readings on T1 and T2 (sensors) will be different. My SimScape model correctly shows this and the heat input does deliver a corresponding temperature difference. The problem is that there is no time delay between the two sensors and no feedback effect that you would expect in a closed loop. I have shown a simple graph of the behaviour that would be expected with a closed loop starting at an initial temperature. I would like my model to be able to vary the time shift of the feedback effect depending on the length of the pipe or the flowrate.
At present, SimScape seems to be modelling it all as a single "lumped" volume. I have attached a more complex model that has some dynamic pulsation behaviour and I would expect to see a time shift between the spikes. I have also attached real data that shows this behaviour. Note in the real data graph that there is a time shift between the sensors and also that there are secondary and tertiary oscillations caused by recirculation of the fluid. This dampens out over time.
EDIT: I believe that the effect that I am trying to describe is correctly called a "transport delay". Some previous (unsuccessful) attempts at this problem can be found here.
I can easily implement a variable delay here for reading the temperatures. This will give me the horizontal time shift that I discuss below but it will do nothing to address the feedback and real physics of the model. It only impacts the reading of the signals and not what's truly going on within the pipe.
How do I implement this transport delay/feedback effect in SimScape?
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/153572/image.png)
The above graph is the expected behaviour that I would expect to see and the graph shown below is real experimental data showing the time shift between sensors.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/153573/image.png)
Here is what my SimScape model shows. Notice that there is no time delay at all between the two sensors.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/153574/image.png)
1 Comment
Answers (0)
See Also
Categories
Find more on Foundation and Custom Domains in Help Center and File Exchange
Products
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!