Your formula looks right except that I don't think the first Tst,previous term on the right hand side should be divided by the Cp,st*m,st.
You can get the temperature at the previous time step by using either Type661 from the TESS Libraries or Type93. Both hold on to output values for a user-specified number of timesteps before releasing them.
I am not entirely clear why you don't want to use an actual storage media model such as Type10, which solves the coupled differential equations that allow you to model stratified storage and also take care of computing the state of the air leaving the storage media so that it can be correctly passed either back to the collector or on to something else.
Best,
david
On 5/18/2012 04:45, Johannes Schütz wrote:
Hello Trnsys-users,
first of all I have to admit, that I'm quite new to Trnsys Studio. So the question might be really easy to answer. I would
be really glad, if you can help me.
My problem is the following:
I have linked a solar air collector to an equation, which is supposed to simulate the sensible storage in a very simplified way.
I assume, that the temperature of the hot air from the collector is constant, also the volume flow and further I assume, that the
heat transfer between the hot air and the heat storage is ideal. That means, that the air is released from the storage at storage
temperature. Last not least I assume that there are no heat lossses to the ambience.
Taking all the assumptions above, an estimation of the storage temperature for each timestep shouldn't be difficult.
I would propose the following formula:
The only problem I face, how to command Trnsys to use the Storage tempearture Tst from the
previous timestep. Hopefully you can help me solving my problem.
Thanks for your help in advance.
Take care
Jojo
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