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chipbarnabychipbarnaby
committed
CSE 0.838
Revised UEF model cooldown function
1 parent eece444 commit cce6f0d

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3 files changed

+33
-109
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3 files changed

+33
-109
lines changed

‎src/CNLOADS.CPP‎

Lines changed: 2 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -3273,7 +3273,6 @@ RC RSYS::rs_SetupASHP() // set ASHP defaults and derived parameters
32733273
if (!IsSet( RSYS_CAP35))
32743274
rs_cap35 = 0.9f * (rs_cap17 + 0.6f * (rs_cap47 - rs_cap17));
32753275

3276-
32773276
#if ASHP_COPREG == 1
32783277
// "traditional" model
32793278
if (!IsSet( RSYS_COP47))
@@ -3338,7 +3337,7 @@ RC RSYS::rs_SetupASHP() // set ASHP defaults and derived parameters
33383337
} // RSYS::rs_SetupASHP
33393338
//----------------------------------------------------------------------------
33403339
float RSYS::rs_Cap17RatioASHP() const
3341-
// returns ration cap17 / cap47
3340+
// returns ratio cap17 / cap47
33423341
{
33433342
#if defined( ASHP_CAPRAT2)
33443343
// multi-segment model from Abram Conant, 5-31-2013
@@ -3766,7 +3765,7 @@ void RSYS::rs_EnteringAirState( // RSYS entering air state
37663765
printf( "Dubious low return tdb\n");
37673766
else if (afRet.as_tdb > 110.f)
37683767
printf( "Dubious high return tdb\n");
3769-
#endif
3768+
#endif
37703769
}
37713770
}
37723771
rs_asRet = afRet; // state = flow w/o amf
@@ -4213,8 +4212,6 @@ RC RSYS::rs_FinalizeSh()
42134212
rs_PLF = 1.f - rs_CdH * ( 1.f - rs_runF);
42144213

42154214
rs_inPrimary = rs_outSen / (rs_effHt * rs_PLF); // compressor input
4216-
4217-
42184215
#else
42194216
double outTot = rs_runF * rs_capHt; // total output (incl fan), Btuh
42204217
// rs_outLat = 0.; // total latent output

‎src/DHWCalc.cpp‎

Lines changed: 28 additions & 103 deletions
Original file line numberDiff line numberDiff line change
@@ -1715,18 +1715,19 @@ RC DHWHEATER::wh_InstUEFInit() // one-time setup for UEF-based instantaneous mo
17151715
// returns RCOK on success
17161716
// else other -- do not run
17171717
{
1718-
#if 1
1719-
// parameters used in deriving runtime coefficients
1718+
// parameters used in deriving runtime coefficients
1719+
// from Tankless WH consumption calculations for ACM.18.doc
1720+
// J. Lutz, 28 July 2017
17201721
struct UEFPARAMS
17211722
{ float flowMax; float flowRE;
17221723
float A; float B; float qOutUEF; float qOutRE; float durRE; float honUEF;
17231724
};
17241725
static const UEFPARAMS UEFParams[] = {
1725-
// size flowMax flowRE A B qOutUEF qOutRE durRE honUEF
1726-
{ /*very small*/ 0.f, 1.f, 10.f, 5.3500f, 5452.f, 1090.f, 2.000f, 0.1667f },
1727-
{ /*low*/ 1.7f, 1.7f, 22.3529f, 9.0882f, 20718.f, 8178.f, 8.824f, 0.4275f },
1728-
{ /*medium*/ 2.8f, 1.7f, 32.3529f, 9.6020f, 29987.f, 8178.f, 8.824f, 0.5941f },
1729-
{ /*high*/ 4.f, 3.f, 28.00f, 9.7902f, 45798.f, 14721.f, 9.000f, 0.6542f },
1726+
// size flowMax flowRE A B qOutUEF qOutRE durRE honUEF
1727+
{ /*very small*/ 0.f, 1.f, 10.f, 3.62150f, 5452.f, 1090.f, 2.000f, 0.1667f },
1728+
{ /*low*/ 1.7f, 1.7f, 22.3529f, 5.78215f, 20718.f, 8178.f, 8.824f, 0.4275f },
1729+
{ /*medium*/ 2.8f, 1.7f, 32.3529f, 6.30610f, 29987.f, 8178.f, 8.824f, 0.5941f },
1730+
{ /*high*/ 4.f, 3.f, 28.00f, 6.42050f, 45798.f, 14721.f, 9.000f, 0.6542f },
17301731
{ /*terminator*/ 9999999.f }};
17311732

17321733
RC rc = RCOK;
@@ -1740,9 +1741,14 @@ static const UEFPARAMS UEFParams[] = {
17401741
const UEFPARAMS& UP = UEFParams[ iSize];
17411742

17421743
// fraction of energy use that is fuel
1743-
double F = 0.99;
1744-
if (wh_annualFuel > 0.f) // insurance
1745-
F = 1./(1. + (wh_annualElec/wh_annualFuel)*3412./100000.);
1744+
double F;
1745+
if (wh_annualFuel < .000001f)
1746+
F = 1.; // nothing known about electrical use
1747+
else
1748+
{ F = 0.99;
1749+
if (wh_annualFuel > 0.f) // insurance
1750+
F = 1./(1. + (wh_annualElec/wh_annualFuel)*3412./100000.);
1751+
}
17461752

17471753
// electrical power during operation (recovery), W
17481754
double Pe = (wh_annualElec * 1000./365. - wh_stbyElec * (24.-UP.honUEF))
@@ -1777,62 +1783,6 @@ static const UEFPARAMS UEFParams[] = {
17771783
// wh_cycLossElec = 0.f; // electricity use per start, Btu
17781784
// unused in revised model 5-24-2017
17791785

1780-
#else
1781-
// parameters used in deriving runtime coefficients
1782-
struct UEFPARAMS
1783-
{ float flowMax; float flowRE;
1784-
float A; float B; float C; float D; float E; float honUEF;
1785-
};
1786-
static const UEFPARAMS UEFParams[] = {
1787-
// size flowMax flowRE A B C D E honUEF
1788-
{ /*very small*/ 0.f, 1.f, 5452.f, 9814.f, -8.00f, 1090.f, 2.000f, 0.1667f },
1789-
{ /*low*/ 1.7f, 1.7f, 20718.f, 89960.f, -74.71f, 8178.f, 8.824f, 0.4275f },
1790-
{ /*medium*/ 2.8f, 1.7f, 29987.f, 98138.f, -73.53f, 8178.f, 8.824f, 0.5941f },
1791-
{ /*high*/ 4.f, 3.f, 45798.f, 206090.f, -98.00f, 14721.f, 9.000f, 0.6542f },
1792-
{ /*terminator*/ 9999999.f }};
1793-
1794-
RC rc = RCOK;
1795-
1796-
// determine size bin
1797-
int iSize;
1798-
for (iSize=0; iSize < 4; iSize++)
1799-
{ if (UEFParams[ iSize+1].flowMax > wh_ratedFlow)
1800-
break;
1801-
}
1802-
const UEFPARAMS& UP = UEFParams[ iSize];
1803-
1804-
// fraction of energy use that is fuel
1805-
double F = 0.99;
1806-
if (wh_annualFuel > 0.f) // insurance
1807-
F = 1./(1. + (wh_annualElec/wh_annualFuel)*3412./100000.);
1808-
1809-
// electrical power during operation (recovery), W
1810-
double Pe = (wh_annualElec * 1000./365. - wh_stbyElec * (24.-UP.honUEF))
1811-
/ UP.honUEF;
1812-
if (Pe < 0)
1813-
rc |= oer( "Inconsistent input for whAnnualElec (=%.2f kWh) and whStbyElec (=%.2f W).\n"
1814-
" Derived operating electrical power is < 0.",
1815-
wh_annualElec, wh_stbyElec);
1816-
1817-
float P = F * (UP.A/wh_UEF - UP.B/ wh_eff) / UP.C; // fuel at flow=flowRE and deltaT=67, Btu/min
1818-
1819-
wh_cycLossFuel = F * (UP.D / wh_eff) - P*UP.E; // startup fuel, Btu/cycle
1820-
1821-
1822-
// max flow per tick, gal-F/tick
1823-
// Top.tp_subhrTickDur = tick duration, min
1824-
wh_maxFlowX = wh_ratedFlow * Top.tp_subhrTickDur * 67.f;
1825-
1826-
// fuel input: Btu/tick at flow=maxFlow and deltaT=67
1827-
wh_maxInpX = P // Btu/min at flow=flowRE and deltaT=67
1828-
* (wh_ratedFlow / UP.flowRE) // scale to max flow
1829-
* Top.tp_subhrTickDur; // scale to actual tick duration
1830-
1831-
// no electricity use pending model development
1832-
wh_operElec = Pe * BtuperWh; // electrical power during opration, Btuh
1833-
// wh_cycLossElec = 0.f; // electricity use per start, Btu
1834-
// unused in revised model 5-24-2017
1835-
#endif
18361786
return rc;
18371787
} // DHWHEATER::wh_InstUEFInit
18381788
//----------------------------------------------------------------------------
@@ -1858,7 +1808,6 @@ RC DHWHEATER::wh_InstUEFDoSubhr(
18581808
// max vol that can be heated in 1 tick
18591809
double drawFullLoad = wh_maxFlowX / deltaT;
18601810

1861-
#if 1
18621811
// carry-forward: instantaneous heaters throttle flow to maintain temp.
18631812
// here represented by carrying forward a limited amount of unmet load
18641813
wh_HPWHxBU = 0.; // heat in excess of capacity (after carry-forward)
@@ -1886,8 +1835,18 @@ RC DHWHEATER::wh_InstUEFDoSubhr(
18861835
else
18871836
nTickFullLoad += drawForTick / drawFullLoad;
18881837
if (wh_stbyTicks) // if no draw in prior tick
1889-
{ // cold start after 30 min, linearly reduced for short times
1890-
nColdStarts += min( 1., wh_stbyTicks * Top.tp_subhrTickDur / 30.);
1838+
{ double offMins = wh_stbyTicks * Top.tp_subhrTickDur;
1839+
#if 1 // exponential cool-down, 7-29-2017
1840+
// exponential cooldown
1841+
static const double TC = 50.06027; // cooldown time constant
1842+
double r = offMins / TC;
1843+
nColdStarts += r > 10. ? 1. : 1.-exp(-r); // avoid underflow
1844+
// printf( "\n%0.2f %0.4f", offMins, nColdStarts);
1845+
1846+
#else
1847+
x // cold start after 30 min, linearly reduced for short times
1848+
x nColdStarts += min( 1., offMins / 30.);
1849+
#endif
18911850
wh_stbyTicks = 0;
18921851
}
18931852
}
@@ -1903,40 +1862,6 @@ RC DHWHEATER::wh_InstUEFDoSubhr(
19031862
// double startElec = wh_cycLossElec * nTickStart; // unused in revised model
19041863
// standby in ticks w/o draw
19051864
double stbyElec = wh_stbyElec * (Top.tp_nSubhrTicks-nTickNZDraw) * tickDurHr;
1906-
#else
1907-
double volxBU = 0.; // volume in excess of capacity, gal
1908-
int nTickNZDraw = 0; // count of ticks with draw > 0
1909-
double nTickFullLoad = 0.; // fractional ticks of equiv full load
1910-
int nTickStart = 0; // # of startup ticks (draw changes 0 -> nz)
1911-
for (int iT=0; !rc && iT<Top.tp_nSubhrTicks; iT++)
1912-
{
1913-
double drawForTick = draw[ iT]*scale*wh_mixDownF + drawLoss; // gal
1914-
if (drawForTick > 0.)
1915-
{ nTickNZDraw++;
1916-
if (drawForTick > drawFullLoad)
1917-
{ nTickFullLoad += 1.; // full capacity operation
1918-
volxBU += drawForTick - drawFullLoad; // excess demand, gal
1919-
}
1920-
else
1921-
nTickFullLoad += drawForTick / drawFullLoad;
1922-
if (wh_stbyTicks) // if no draw in prior tick
1923-
nTickStart++; // count start
1924-
}
1925-
else
1926-
// standby
1927-
wh_stbyTicks++; // reset draw duration
1928-
}
1929-
1930-
double tickDurHr = Top.tp_subhrTickDur / 60.; // tick duration, hr
1931-
double rcovFuel = wh_maxInpX * nTickFullLoad;
1932-
double startFuel = wh_cycLossFuel * nTickStart;
1933-
double rcovElec = wh_operElec * nTickNZDraw * tickDurHr; // assume operation for entire tick with any draw
1934-
// double startElec = wh_cycLossElec * nTickStart; // unused in revised model
1935-
// standby in ticks w/o draw
1936-
double stbyElec = wh_stbyElec * (Top.tp_nSubhrTicks-nTickNZDraw) * tickDurHr;
1937-
wh_HPWHxBU = 8.345 * volxBU * deltaT;
1938-
// excess heating required to meet ws_tUse
1939-
#endif
19401865

19411866
// energy use accounting, Btu
19421867
double inFuel = rcovFuel + startFuel;

‎src/csevrsn.h‎

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -14,14 +14,16 @@
1414
// version # for current build
1515
// change ONLY here
1616
#define CSEVRSN_MAJOR 0
17-
#define CSEVRSN_MINOR 836
17+
#define CSEVRSN_MINOR 838
1818

1919
// version # as quoted text ("x.xxx")
2020
#define CSEVRSN_TEXT MAKE_LIT(CSEVRSN_MAJOR##.##CSEVRSN_MINOR)
2121

2222
// ONLY comments below here
2323

2424
/* History:
25+
0.838: Instantaneous DHW UEF model w/ revised exponential cooldown, 8-1-2017
26+
0.837: Instantaneous DHW UEF model w/ exponential cooldown, 7-29-2017
2527
0.836: heat pump autosize: now uses ACM algorithm when both cap47 and cap95 autosized
2628
committed 7-20-2017
2729
0.835: heat pump autosize: don't force cap95 to be consistent with cap47

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