chiller

  • CHILLER Capacity user inputs. Capacity at various temp conditions is cap = chCapDs*chPyCapT(ts,tcnd).
  • Note Niles chlrType deleted per Taylor (via Bruce), defaults hard-coded to HERM_CENT case.
Name Type Variability Description/Comments
chCapDs POWER_NZ Start of phase
  • capacity at chDsTs,chDsTcnd, Btuh. Required. Negative internally. Niles capDsn.
  • verify defaults 44 and 85 should be described as ARI in doct'n. *****
chTsDs TEMP_GZ Start of phase temp leaving chiller at which chCapDs applies, default 44. Niles twSuDsn.
chTcndDs TEMP_GZ Start of phase temp entering condenser (twoDel value) for chCapDs, default 85. Niles twCndDsn.
chPyCapT
  • biquad poly (6 float coeffs entered) of (chTs, chTcnd) to adjust capacity to off-design temps.
  • Niles capNrCr. Normalized @ [chTsDs][chtsds]/[chTcndDs][chtcndds]; Niles' capRat not used.
  • Defaults: -1.742040,.029292,-.000067,.048054,-.000291,-.000106 or as changed, cncult6.cpp.
  • [CHILLER][chiller] Full-load energy Input Inputs. Full-load power input at various temp conditions is eiFL = cap*[chEirDs][cheirds]*chPyEirT(ts,tcnd).
PYBIQUAD
Name Type Variability Description/Comments
chPyCapT.k[index] number Array [7] Start of run FLOAT k[7]. One extra member needed as terminator by cul.cpp array input logic, 5-92.
chCop FLOAT_GZ Start of phase
  • Full-load Coefficient of performance (output Btu/input Btu) @ [chTsDs][chtsds]/[chTcndDs][chtcndds], reflecting
  • motor and chiller efficiency. No such Niles input. Converted to [chEirDs][cheirds] for internal use.
  • Default: current minimum erriciency, Bruce to look up ??, meanwhile can use 3 for testing.
chEirDs FLOAT_GZ Start of run
  • Full-load eir (energy input ratio) @ [chTsDs][chtsds]/[chTcndDs][chtcndds], relecting motor and chiller efficiency.
  • Alternate input for [chCop][chcop]; used internally; replaces Niles' eirR (eir at ARI conditions).
chPyEirT
  • biquad poly (6 float coeffs input) of (chTs, chTcnd) to adjust full-load energy input to
  • off-rated temperature conditions, Niles eirNrCr. 1.0 @ [chTsDs][chtsds]/[chTcndDs][chtcndds].
  • Defaults: 3.117600,-.109236,.001389,.003750,.000150,-.000375 (or as changed, cncult6.cpp).
  • [CHILLER][chiller] part-load energy Input Inputs. Part-load energy input (ei) is full-load-energy-input (eiFL, above) corrected as follows:
  • In unloading region, 1 >= plr > [chMinUnldPlr][chminunldplr], ei is curve given by polynomial
  • ei = eiFl * chPyEirUl(plr);
  • In false loading region, [chMinUnldPlr][chminunldplr] >= plr >= [chMinFsldPlr][chminfsldplr], energy input is constant.
  • ei = eiFl * chPyEirUl([chMinUnldPlr][chminunldplr]); nb no plr dependence
  • In cycling region, [chMinFsldPlr][chminfsldplr] > plr >= 0, ei is prorated (eir remains constant).
  • ei = eiFl * chPyEirUl([chMinUnldPlr][chminunldplr])*plr/[chMinUnldPlr][chminunldplr].
  • The value "chPyEirUl([chMinUnldPlr][chminunldplr])" is constant and will be precomputed at setup time.
  • Niles name "eirPlrCr" for the above 3-case part load correction factor is not used in record.
PYBIQUAD
Name Type Variability Description/Comments
chPyEirT.k[index] number Array [7] Start of run FLOAT k[7]. One extra member needed as terminator by cul.cpp array input logic, 5-92.
chPyEirUl
  • cubic poly (4 floats input for coeff) of plr to correct eir for plr in unloading range
  • (1 >= plr > [chMinUnldPlr][chminunldplr]). Niles eirUnldCr. Defaults:.222903,.313387,.463710,0. (cncult6.cpp).
PYCUBIC
Name Type Variability Description/Comments
chPyEirUl.k[index] number Array [5] Start of run
  • FLOAT k[5]. One extra member needed as terminator by cul.cpp array input logic, 5-92.
  • possible future setup optimizations: 1) select ptr to fcn that does not compute terms whose k is 0;
  • 2) precalculate constants to compute in form ((x*k[3] + k[2])*x + k[1])*x + k[0]
chMinUnldPlr number Start of phase min unloading loading part load ratio, default 0.1. Niles minUnLdPlr.
chMinFsldPlr number Start of phase
  • min false loading part load ratio, default 0.1. Niles minFsLdPlr. must be <= [chMinUnldPlr][chminunldplr].
  • [CHILLER][chiller] user inputs...
chMotEff FRAC_GZ Start of phase
  • motor efficiency (poorly named), default 1.0, Niles motorEff, used only to determine
  • portion of input energy computed as above that goes to the air rather than the condenser.
  • 1.0 simulates hermetic compressor where all motor waste heat goes to condenser;
  • use smaller values for open systems.
mtri TI input time
  • [METER][meter] name ("[chMtr][chmtr]") for accumulating compressor energy used by chiller,
  • under category AUX. Default: not recorded. Note pumps have their own meters.
chpp
  • chiller primary pump: pumps water through primary loop to which the load (CHW coils)
  • is connected. Flow is unsimulated, but assumed to be at least [chppGpm][chppgpm]=chpp.mw whenever
  • chiller is on (any excess over coil flows goes thru an assumed bypass valve); if flow
  • overruns this amount, it is assumed that the (unsimulated) pressure drops such that the
  • pump electrical input and heat do not change. Subrecord inputs include:
  • [chppGpm][chppgpm] gpm > 0 Primary pump flow. Default [chCapDs][chcapds]/5000. Niles mwPrmPmp.
  • chppHdlos ft H2O >= 0 Head loss in primary chilled water loop. default 65. Niles hdLosPrmLp.
  • [chppMotEff][chppmoteff] frac > 0 Primary pump motor efficiency, default .88. Niles mtrEfPrmPmp.
  • [chppHydEff][chpphydeff] frac > 0 Hydraulic efficiency of primary pump, default .70 . Niles hydEfPrmPmp.
  • [chppOvrunF][chppovrunf] factor > 1 Maximum multiple of chppMw that pump can deliver at (assumed) pressure reduction,
  • and at same electrical input. default 1.3. CSE currently does not simulate primary flow
  • at run time, but will issue a warning if the sum of the flows of the connected CHW coils
  • exceeds the sum of the [COOLPLANT][coolplant]'s most powerful stage's [chppGpm][chppgpm]*[chppOvrunF][chppovrunf] products.
  • Drop this input if not checking coil capacity vs pumping capacity 10-92.
  • chppMtr .mtri name of a [METER][meter] for recording electricity used by pump, category AUX.
PUMP
Name Type Variability Description/Comments
chpp.gpm H2OFLOW_GZ Start of run rated flow (gpm), delivered at HdLoss. required input. code defaults .gpm for blrp, chcp, chpp.
chpp.hdLoss PRESH2O_GEZ Start of phase head (pressure), ft-H2O. Accept 0 for 0 pump heat. Default CHW: 65; CW:45; HW:35.
chpp.motEff FRAC_GZ Start of phase motor efficiency, default .88
chpp.hydEff FRAC_GZ Start of phase hydraulic eff, default .70. Only product of motEff * hydEff is used.
chpp.ovrunF number Start of run
  • overrun factor for future use, now 9-92 set to constant 1.3.
  • maximum deliverable flow at (assumed) reduced head, as multiple of Gpm.
chpp.mtri TI Start of phase
  • name of MTR to which electrical use is added
  • PUMP setup time variables
chpp.mw DBL Start of run
  • MFLOW
  • rated flow, Gpm converted to lb/hr
  • *r DBL/*MFLOW*/ mwMx rated flow times ovrun, lb/hr -- if needed
chpp.q DBL Start of run
  • POWER
  • shaft power === heat to water, Btuh
chpp.p DBL Start of run
  • POWER
  • electrical input, whenever running, Btuh: flow in application always at least mw;
  • overruns at least to mwMx are assumed not to increase power (pressure drops).
chcp
  • chiller heat rejection (condenser) pump: pumps water through chiller's condenser and
  • the chiller's coolplant's towerplant's cooling towers. Flow is [chcpGpm][chcpgpm]=chcp.mw
  • whenever chiller is on. Subrecord inputs include the following:
  • [chcpGpm][chcpgpm] gpm > 0 Condenser pump flow, default [chCapDs][chcapds]/4000, Niles mwCndPmp.
  • chcpHdlos ft H2O >= 0 Head loss in condenser chilled water loop, default 45', Niles hdLosCndLp.
  • [chcpMotEff][chcpmoteff] frac > 0 Condenser pump motor efficiency, default .88, Niles mtrEfCndPmp.
  • [chcpHydEff][chcphydeff] frac > 0 Hydraulic efficiency of condenser pump, default .70, Niles hydEfCndPmp.
  • chcpMtr .mtri name of a [METER][meter] for recording electricity used by pump, category AUX.
  • [CHILLER][chiller] auxiliaries user inputs, similar to those for a [BOILER][boiler] or a COIL.
PUMP
Name Type Variability Description/Comments
chcp.gpm H2OFLOW_GZ Start of run rated flow (gpm), delivered at HdLoss. required input. code defaults .gpm for blrp, chcp, chpp.
chcp.hdLoss PRESH2O_GEZ Start of phase head (pressure), ft-H2O. Accept 0 for 0 pump heat. Default CHW: 65; CW:45; HW:35.
chcp.motEff FRAC_GZ Start of phase motor efficiency, default .88
chcp.hydEff FRAC_GZ Start of phase hydraulic eff, default .70. Only product of motEff * hydEff is used.
chcp.ovrunF number Start of run
  • overrun factor for future use, now 9-92 set to constant 1.3.
  • maximum deliverable flow at (assumed) reduced head, as multiple of Gpm.
chcp.mtri TI Start of phase
  • name of MTR to which electrical use is added
  • PUMP setup time variables
chcp.mw DBL Start of run
  • MFLOW
  • rated flow, Gpm converted to lb/hr
  • *r DBL/*MFLOW*/ mwMx rated flow times ovrun, lb/hr -- if needed
chcp.q DBL Start of run
  • POWER
  • shaft power === heat to water, Btuh
chcp.p DBL Start of run
  • POWER
  • electrical input, whenever running, Btuh: flow in application always at least mw;
  • overruns at least to mwMx are assumed not to increase power (pressure drops).
auxOn POWER_GEZ Start of hour addl input energy used in proportion to plr when on, default 0, hourly vbl for future flexblty.
auxOnMtri TI input time MTR to which to charge "auxOn"
auxOff POWER_GEZ Start of hour addl input energy when off for part or all of subhr (proportional to 1-plr), for unforseen uses.
auxOffMtri TI input time MTR for "auxOff"
auxOnAtall POWER_GEZ Start of hour addl input energy used in toto when chiller on for any part of subhour, for unforseen uses.
auxOnAtallMtri TI input time MTR for "auxOnAtall"
auxFullOff POWER_GEZ Start of hour additional input energy when off FOR ENTIRE SUBHOUR (as opposed to in proportion to 1-plr).
auxFullOffMtri TI input time MTR to which auxFullOff is charged, default c.mtri.

CHILLER setup time variables

Name Type Variability Description/Comments
nxCh4cp TI Start of run 0 or subscript of next CHILLER in same COOLPLANT. 1st is COOLPLANT.ch1.
used BOO Start of run non-0 if a COOLPLANT uses this chiller -- else warning
eirMinUnldPlr DBL Start of run chPyEirUl(minUnldPlr): precomputed energy input corr for false loading, prorate for cycling

CHILLER runtime internal variables

Name Type Variability Description/Comments
chMode choice:OFFON End of subhour C_OFFONCH_OFF or _ON: whether this chiller is running, set by staging code.
cap DBL End of subhour
  • POWER
  • capacity @ current cpTs and tCnd, set only if running
  • [CHILLER][chiller] runtime outputs. Pri water ts, towerplant water q & temp, etc. are computed directly into [COOLPLANT][coolplant] members.
q number End of subhour this chiller's current primary output power to pri loop
p number End of subhour compressor power input. also see chpp.p, chcp.p. (Niles cndPmpPwrIn, prmPmpPwrIn, totPwrIn)
pAuxOn number End of subhour chiller-on proporotinal aux power this subhour
pAuxOff number End of subhour chiller-off proportional aux power this subhour
pAuxOnAtall number End of subhour chiller on-at-all aux power this subhour
pAuxFullOff number End of subhour auxFullOff power this subhour