Add Heating Design Capacity sizing report for ZoneHVAC:Baseboard:RadiantConvective:Water - #11765
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| Real64 constexpr HighWaterMassFlowRate(10.0); // Maximum limit of water mass flow rate in kg/s - these should be 1000x of volume flow | ||
| Real64 constexpr LowWaterMassFlowRate(0.00001); // Minimum limit of water mass flow rate in kg/s | ||
| Real64 constexpr MaxWaterFlowRate(10.0); // Maximum limit of water volume flow rate in m3/s | ||
| Real64 constexpr MaxWaterFlowRate(10.0); // Maximum limit of water volume flow rate in m3/s - these should be 1/1000 of mass flow |
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@RKStrand, which of these seems to be a proper limit? Probably kg/s because m3 -> gal is 264x so 2640 gal/sec for volume. That's quite the pump. I just noticed this while working through this issue and highlighted it with a comment.
! m3 => gal 264.172037284185
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@rraustad Sorry--just getting to this. You caught me at a busy time with the semester starting yesterday. I think your assessment is correct. I think it's supposed to be kg/s and that was likely a mistake in the original implementation, which on second thought I think might have been done by me (rather than Daeho). In that case, it probably was done 20 years ago.
| DesCoilLoad = RatedCapacityUser; | ||
| WaterMassFlowRateStd = hWBaseboard.WaterMassFlowRateStd; | ||
| } else if (hWBaseboard.RatedCapacity == DataSizing::AutoSize || hWBaseboard.RatedCapacity == 0.0) { | ||
| DesCoilLoad = RatedCapacityDes; |
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I need to think about this block a little more.
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This boils down to a simple choice. BB size > 0, else use zone design load, WaterTempAvg and WaterMassFlowRateStd cannot be <= 0 so those were removed and that leaves the BB capacity. If > 0 then use it, else use the zone load. If both are 0 then the BB (actually UA in this area of code, which is the last parameter sized) sizes to 0.
thisHWBaseboard.WaterTempAvg = state.dataIPShortCut->rNumericArgs(1);
ZoneHVAC:Baseboard:RadiantConvective:Water,
N1, \field Rated Average Water Temperature
\maximum 150.0
\minimum 20.0
\units C
\default 87.78
thisHWBaseboard.WaterMassFlowRateStd = state.dataIPShortCut->rNumericArgs(2);
ZoneHVAC:Baseboard:RadiantConvective:Water,
N2, \field Rated Water Mass Flow Rate
\maximum 10.0
\minimum> 0.0
\units kg/s
\default 0.063
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This change is also the reason the unit test value changed at line 368. If the BB is hard-sized then sizing uses the BB input for Rated Water Mass Flow Rate (line 1113) to calculate UA. If the BB is autosized (as in the unit test) then sizing uses the BB Maximum Water Flow Rate (line 1117). This branch always uses the Rated Water Mass Flow Rate as the design condition. Rated Average Water Temperature is used in either case. But this only holds true when Heating Design Capacity Method = HeatingDesignCapacity. CapacityPerFloorArea and FractionOfAutosizedHeatingCapacity always uses Rated Water Mass Flow Rate. @RKStrand, do you have some insight into which would be correct? i.e., when should rated vs actual water flow rate be used in the design UA calculation? If this unit test had used a different Heating Design Capacity Method then the answer would not have changed. I could revise this if necessary.
" 87.78, !- Rated Average Water Temperature {C}",
" 0.063, !- Rated Water Mass Flow Rate {kg/s}",
" autosize, !- Heating Design Capacity {W}",
" autosize, !- Maximum Water Flow Rate {m3/s}",
" ZoneHVAC:Baseboard:RadiantConvective:Water:Design,", both use
" Baseboard Design, !- Name",
" HeatingDesignCapacity, !- Heating Design Capacity Method",
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This is actually a really good question but also one from a long time ago. While Fred B did a lot of the autosizing stuff, I think this came after his work and I think was done by Daeho Kang. If I remember correctly, and that's a big IF, the sizing in the baseboard routine followed the prevailing baseboard standard (I-B-R or something like that) at the time. That was so that if users got rating information from a manufacturer which presumably followed that standard they could get that to function in E+. Of course, that was over 10 years ago and the standard was several years old at the time so maybe close to 20 years old. I have no idea what if anything has been done in the meantime. So, I think that is why the code did what it did. Is that still correct and/or should we do something else? Someone would have to track down whatever is current and see. I'll admit that the standard back then felt a bit clunky to implement so I have a tough time advocating for it and not some other common sense approach. Not sure if any of that helps...
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Thanks @RKStrand. Safest bet is to revert this back to where it was. This is not the correct branch to make this type of change.
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This comment looks unresolved. Is there something to revert back here?
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de6395a reverted the behavior to what it was before.
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de6395a reverted the behavior to what it was before.
Thank you
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| } else { | ||
| CheckZoneSizing(state, cCMO_BBRadiator_Water, hWBaseboard.Name); | ||
| DesCoilLoad = RatedCapacityDes; | ||
| DesCoilLoad = RatedCapacityUser; |
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This looks like a change, but I'm not sure it is. Line 1048 saved the BB capacity in RatedCapacityDes, now it's saved in RatedCapacityUser. Eyes on diffs because existing unit test changed.
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| "Design Size Heating Design Capacity [W], 1300", | ||
| false)); | ||
| EXPECT_TRUE(compare_eio_stream_substring("Component Sizing Information, ZoneHVAC:Baseboard:RadiantConvective:Water, THISISABASEBOARD, " | ||
| "User-Specified Heating Design Capacity [W], 650")); |
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Do these result make sense? If the capacity is reduced by half (650 vs 1300), and the water flow rate is reduced by half (1.6E-5 vs 3E-5), then I would think UA would be roughly the same, But UA was also reduced by half (11.7 vs 24.4?? Any HX theory experts out there?
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Q = Mdot * Cp * deltaT shows Mdot is proportional to Q, assuming deltaT is fixed, and Q = UA * deltaT shows UA is proportional to Q. So this does make sense that when Q is reduced by 1/2, both Mdot and UA are reduced by 1/2. So this result seems reasonable.
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I tested 5ZoneWaterCooled_Baseboard every way I could think of. Hard-sized, autosized, and all 3 scalable sizing methods. Results made sense in all cases. Example output: 
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The issue notes the water cooling coil is missing the Design Air Flow Rate sizing result (using same test file). I see that report in the eio: Coil:Cooling:Water, field N2, Design Air Flow Rate. There is no corresponding field in the eplusout.sql table 
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…into 7017-Autosize-Fields-Inconsistent
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@mitchute My name was added here as a reviewer, but I generally only provide comments on various aspects of some bug fixes. What are you needing from me with this one? |
@RKStrand I'm guessing that @rraustad added you, but it looks like you two have already worked out your questions, so I think you're done ✔️ |
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@rraustad I think you can take one more quick look here, then this one is probably ready. |
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Yes, if I ever touch a Radiant component I do like when @RKStrand says it looks OK. |
The Oracle of |
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Well, there's always something radiating here...not always good, sometimes kinda not so great. But glad to have been reassuring here. Definitely not claiming any sort of oracle status...curmudgeon maybe? |
4 participants
Pull request overview
Description of the purpose of this PR
ZoneHVAC:Baseboard:RadiantConvective:Water does not report Heating Design Capacity as expected.
Pull Request Author
Reviewer