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Why the heating coil electric energy of heat pump was different for the same case but with using E+ 8.2 and E+ 8.3?

asked 2016-07-14 18:30:47 -0500

Jallen's avatar

updated 2016-07-15 08:16:25 -0500

I used E+8.2 and E+8.3 to run the same heat pump project, but the heating coil electric energy was significant different (larger than 12%). I checked the simulation results and found the only difference was in the "Heating Coil Electric Energy ", the other electricity uses, such as "Heating Coil Defrost Electric Energy ", "Heating Coil Crankcase Heater Electric Energy ", "Air System Heating Coil Total Heating Energy", were almost the same. Thus, I guessed the corrections of partial load performance curve of heat pump might be changed in new version of E+, then I further checked the Performance Curve Input Variable and the Output value, it was found that these values were really different in E+8.2 and E+8.3. The performance curves in different E+ were the same, can check the IDF file( object name: Curve:Quadratic,HPACCOOLPLFFPLR). All the input coefficients in this object are the same for E+8.2 and E+8.3, but the internal Input Variable and the Output value were changed. So, I suspected the E+ developers might change the internal algorithms in getting the Input Variable of part load performance, especially for the object "Sizing:System". From E+8.2 to E+8.3, the object of "Sizing:System" was improved, I am not sure if this is the reason that cause the different results in my simulation. Can anybody here answer my question?

I also run the build-in heat pump example file (HeatPump.idf) using E+8.2 and E+8.3, the same problem and difference was found.

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answered 2016-07-18 02:47:52 -0500

If you're feeling quite the detective, I'd start by checking the Checking the release notes for v8.3 as well as the history for the DXCoils.cc a little prior to the v8.3 release date, on March 30, 2015, and after the release of 8.2 update 1 (if that's what you're using) which was on December 8, 2014.

If your coils are autosized, check the resulting sizes you get in both versions, that might indeed be part of the discrepancy indeed.

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Julien, thanks for your answer. I have checked the v8.3 release note but did not find the answer for my question. I also checked the coils sizes for the both versions, the autosized capacities and flow rates were the same for E+8.2 and E+8.3. Actually, I found the only difference was in the heating electrical energy consumption, the cooling electrical energy consumption was the same.

Jallen's avatar Jallen  ( 2016-07-18 12:18:02 -0500 )edit

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Asked: 2016-07-14 18:30:47 -0500

Seen: 219 times

Last updated: Jul 18 '16