Fix #8599 - Incorrect psychrometric calculation causes error #8833
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@@ -55,6 +55,7 @@ | |
| #include <EnergyPlus/CommandLineInterface.hh> | ||
| #include <EnergyPlus/Data/EnergyPlusData.hh> | ||
| #include <EnergyPlus/DataEnvironment.hh> | ||
| #include <EnergyPlus/DataGlobalConstants.hh> | ||
| #include <EnergyPlus/General.hh> | ||
| #include <EnergyPlus/Psychrometrics.hh> | ||
| #include <EnergyPlus/UtilityRoutines.hh> | ||
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@@ -498,7 +499,9 @@ namespace Psychrometrics { | |
| for (iter = 1; iter <= itmax; ++iter) { | ||
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| // Assigning a value to WBT | ||
| if (WBT >= (tBoil - 0.09)) { | ||
| WBT = tBoil - 0.1; | ||
| } | ||
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| // Determine the saturation pressure for wet bulb temperature | ||
| PSatstar = | ||
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@@ -523,10 +526,9 @@ namespace Psychrometrics { | |
| WBT = ResultX; | ||
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| // If converged, leave iteration loop. | ||
| if (icvg == 1) { | ||
| break; | ||
| } | ||
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There was a problem hiding this comment. Removed the "Error Trap for the Discontinuous nature of PsyPsatFnTemp function (Sat Press Curve) at ~0 Deg C." since it's no longer discontinuous. There was a problem hiding this comment. I vaguely remember this. It looks like the unit tests hits this so good there. Gotta check it though. There was a problem hiding this comment. Yeah, I remember this now, this is a check for where this used to have a problem. Now that the problem is corrected, this check is no longer needed. |
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| } // End of Iteration Loop | ||
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@@ -682,6 +684,11 @@ namespace Psychrometrics { | |
| // Compared to Table 3 values (August 2007) with average error of 0.00%, max .30%, | ||
| // min -.39%. (Spreadsheet available on request - Lawrie). | ||
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| // Note: the ASHRAE Handbook of Fundamentals is being slightly inaccurate in its wording, | ||
| // and referring to Eq 5 applying to -100°C to 0°C and Eq 6 applying to 0°C to 200°C | ||
| // In fact, it is **not** 0°C, but the triple-point of water, which is 0.01°C. Evaluating the Eq 5 and 6 up to and from the triple-point | ||
| // is removing the discontinuity altogether. | ||
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There was a problem hiding this comment. I think you were actually the one that found this critical point. Nice! |
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| // USE STATEMENTS: | ||
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| // Return value | ||
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@@ -734,29 +741,34 @@ namespace Psychrometrics { | |
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| // If below -100C,set value of Pressure corresponding to Saturation Temperature of -100C. | ||
| if (Tkel < 173.15) { | ||
| Pascal = 0.001405102123874164; | ||
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There was a problem hiding this comment. @rraustad and I noted that the value below -100°C does not match the evaluation of the equation at -100°C. So align. |
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| // If below freezing, calculate saturation pressure over ice. | ||
| } else if (Tkel < DataGlobalConstants::TriplePointOfWaterTempKelvin) { // Tkel >= 173.15, Tkel < 273.16 (0.01°C) | ||
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| Real64 constexpr C1(-5674.5359); | ||
| Real64 constexpr C2(6.3925247); | ||
| Real64 constexpr C3(-0.9677843e-2); | ||
| Real64 constexpr C4(0.62215701e-6); | ||
| Real64 constexpr C5(0.20747825e-8); | ||
| Real64 constexpr C6(-0.9484024e-12); | ||
| Real64 constexpr C7(4.1635019); | ||
| Pascal = std::exp(C1 / Tkel + C2 + Tkel * (C3 + Tkel * (C4 + Tkel * (C5 + C6 * Tkel))) + C7 * std::log(Tkel)); | ||
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| // If above freezing, calculate saturation pressure over liquid water. | ||
| } else if (Tkel <= 473.15) { // Tkel >= 173.15 // Tkel >= TriplePointOfWaterTempKelvin | ||
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There was a problem hiding this comment. The else if above is Tkel < Real64 constexpr TriplePointOfWaterTempKelvin = 273.16; and this is <= 473.15 ... oh yeah, this is the top end so comment is wrong. There was a problem hiding this comment. These comments are a little confusing but a second looks shows they say what they said before with updates to what was changed. I'd say this is OK. There was a problem hiding this comment. I think the comments provide little value overall here, but there were pre-existing. and they should be correct. |
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| #ifndef EP_IF97 | ||
| Real64 constexpr C8(-5800.2206); | ||
| Real64 constexpr C9(1.3914993); | ||
| Real64 constexpr C10(-0.048640239); | ||
| Real64 constexpr C11(0.41764768e-4); | ||
| Real64 constexpr C12(-0.14452093e-7); | ||
| Real64 constexpr C13(6.5459673); | ||
| Pascal = std::exp(C8 / Tkel + C9 + Tkel * (C10 + Tkel * (C11 + Tkel * C12)) + C13 * std::log(Tkel)); | ||
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| // If above 200C, set value of Pressure corresponding to Saturation Temperature of 200C. | ||
| } else { // Tkel >= 173.15 // Tkel >= TriplePointOfWaterTempKelvin // Tkel > 473.15 | ||
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There was a problem hiding this comment. So shouldn't this be the top end? 473.15 ? There was a problem hiding this comment. Oh, it's only a comment issue. There was a problem hiding this comment. Same for this comment, these are each true and true as a whole. |
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| Pascal = 1555073.745636215; | ||
| } | ||
| #else | ||
| // Table 34 in IF97 | ||
| Real64 constexpr N1(0.11670521452767e04); | ||
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@@ -776,12 +788,12 @@ namespace Psychrometrics { | |
| Real64 const B = N3 * phi2 + N4 * phi + N5; | ||
| Real64 const C = N6 * phi2 + N7 * phi + N8; | ||
| Pascal = 1000000.0 * pow_4((2.0 * C) / (-B + std::sqrt((B * B) - 4.0 * A * C))); | ||
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| // If above 200C, set value of Pressure corresponding to Saturation Temperature of 200C. | ||
| } else { // Tkel >= 173.15 // Tkel >= KelvinConv // Tkel > 473.15 | ||
| Pascal = 1554671.8682698254; | ||
| } | ||
| #endif | ||
| return Pascal; | ||
| } | ||
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