Re: [EnergyPlus_Support] Custom Phase Change System

Chin,

For modeling PCM tubes in an occupied space I would suggest using the material property phase change object and a sub surface. The sub surface would ideally have the same surface area as the exposed surface area of the tubes, then the thickness would be set in the material property to match the thickness of the tubes as a contiguous layer, while adjusting the density and conductivity to match the PCM. You do not want to try to make a metal shell as a layer of the construction because the Conduction Finite Difference Algorithm does not work with highly conductive and thin layers, so basically you just want to have a construction with only the PCM layer. For the tubing you would want to model the the external metal surface because it would receive radiant exchange from the zone, this can be done by setting the solar and thermal absorbency to correct values for the metal.

I have PCM databases I could and also a custom version of E+ with a new PCM model that you could alpha test if you are interested.

Kind Regards

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

120 E. Pritchard St. | Asheboro, NC 27203

| Mobile 503-688-8951
www.phasechange.com

On Fri, Jan 10, 2014 at 9:26 AM, Chien Si Harriman <chien.harriman@xxxxxxxxx> wrote:

I'll let you know. Great suggestion. Only thing is, the tubes are actually in the occupied space, so they are designed to slowly convect into the room over time.

On Thu, Jan 9, 2014 at 4:36 PM, Jeremiah Crossett <jcrossett@xxxxxxxxxxxxxxx> wrote:

Chin,
I think this can be modeled with the Ice storage detailed model in E+ using the freezing temperature, charge and discharge curves and timestep of curve-- There is also the new DX thermal storage that might be usable.. Not sure if you have already looked into this, but please let me know if you think this would work?

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

120 E. Pritchard St. | Asheboro, NC 27203

| Mobile 503-688-8951
www.phasechange.com

On Thu, Jan 9, 2014 at 4:31 PM, <chien.harriman@xxxxxxxxx> wrote:

Hi There-

I have a technology I found through a colleague in the UK, where the central plant (chiller in this case, only) stores energy in a series of tubes of phase change material/

The chiller piping runs through the middle of these tubes which are packed with phase change material. He has rafts of data that would allow very accurate modeling of the system, including how the phase change capacity changes as a function of temperatures, the calculated convection coefficient, and the convective losses as a function of temperature and flow rate. As much data as any engineer would want...as it was someone's PhD thesis.

I'm asking the group first how difficult it would be to make this happen. I suppose there is not an out-of-the-box solution, but if there is, does anyone know of one?

So if this is custom programming (I have programming experience and am pretty active with the OpenStudio team so I could maybe get them to help me a little bit :) where would I start to build a module or plugin to talk to EnergyPlus? And finally, do you think this will be something that is very hard for a first-timer, given the technology I've described?

Thanks so much,
Chien Si