|
Martin, I would recommend that you make a very simple project where the chiller is subject to a known constant load with known constant outdoor conditions. Hook up a Type65 online plotter to the chiller and take a look at its performance under these known conditions; once the model looks up the performance data in the data file, its computations are really quite simplistic. You can verify them by hand using the documentation in the 04-Mathematical Reference. This will give you some confidence in your model. One of the issues that often occurs in modeling absorption chillers is that if you compute a building load and pass it directly to the chiller then the chiller spends a lot of its time running at a very very low part load. In reality, a chiller can't operate much below 20% capacity so you have to make sure that this is reflected in the data file. The data file should have near zero capacity and near zero fraction of design energy input below about 20% PLR (part load ratio). At one time, I think there was an error in the Type107 example data file that showed too large a capacity at very low PLR. The more correct way to model the system would be to place the chiller on its own primary loop and to place the load on a secondary loop. The loops can be separated by a thermal storage tank whose volume is equal to the volume of the primary and secondary loops. The chiller operates to keep the primary loop cold and the secondary loop draws off only as much as it needs to meet the load. Kind regards, David On 12/19/2012 01:51, Martin Ssembatya
wrote:
-- *************************** David BRADLEY Principal Thermal Energy Systems Specialists, LLC 22 North Carroll Street - suite 370 Madison, WI 53703 USA P:+1.608.274.2577 F:+1.608.278.1475 d.bradley@tess-inc.com http://www.tess-inc.com http://www.trnsys.com |