[EnergyPlus_Support] RE: Solar Heat Pipe System Model - EMS Issues with CTF [1 Attachment]

[<shoaibahmed89@xxxxxxxxx>]

If I use Conduction Finite Difference, it shows sever errors of different amounts of finite difference nodes for the surface change materials.  CFD is also unable to support highly conductive materials such as a solar absorber, or the heat pipe system itself.  

I actually found an error with the idf I posted as I was trying to take this out of a larger simulation for easier reference.  I've switched the inside Zone area of the heat pipe wall to "HEAT PIPE OUT" and changed the calculation for the heat pipe inner space zone to a Trombe Wall Zone Inside Convection Algorithm.

With CTF equipped as the overall heat balance algorithm and varying time steps, the simulation either crashes altogether without errors or crashes due to CTF convergence issues, which is something I've also run into.  By varying the timestep to 6, I receive a "Program terminated for reasons listed (InitConductionTransferFunctions)", even if I have this setup for a warm up.

Attached is the revised for reference.  I am running this with package installed TMY3 epw's at the moment.

Thanks for the input Jeremiah!

---In energyplus_support@xxxxxxxxxxxxxxx, <jcrossett@...> wrote:

Your timestep of 4 could be changed-- I like to use Conduction Finite Difference at

Jeremiah D. Crossett  | Senior Analyst  |  Phase Change Energy Solutions

120 E. Pritchard St.  | Asheboro, NC 27203 

 | Mobile 503-688-8951

www.phasechange.com 

  

On Sat, Nov 30, 2013 at 7:39 PM, <shoaibahmed89@...> wrote:

 

I'm currently working on a model for implementing a passive solar heat pipe system into EnergyPlus.  The way this passive solar heat pipe system works is if the temperature of the outside environment is greater than that of the inside zone, then heat is transferred in, however, if the outside environment is colder, heat transfer through the pipes is ceased due to a thermal diode effect and heat inside is only lost through exterior walls.  Hopefully this is a sufficient explanation.

I was able to get some input from a few people previously (much appreciated) and decided to go down the EMS route and vary the the construction state of the surface with an IF/THEN argument as a program with the outside and inside temperatures being the sensors.  This is necessary because the construction state can be different at any time step with respect to zone and outdoor temperatures.  

I'm running into issues with the CTF and having 'incompatible time steps', or temperature limits causing a fatal crash.  I'm not sure how to resolve this.  I've attempted different ways to model and ultimately run into the same problem.

I've attached a idf for reference.  Let me know if you have any input on this.  I'm hitting my head on a wall over here!

Thanks again all,

Syed

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Attachment not found:
d:\eudora\attach\Heat Pipe Model2.idf