CONTINUOUS_MODEL CeColPnl ABSTRACT "Water fed COoLing PaNeL or convector. If massflow control signal is positive, ideal internal massflow control is enabled. Requested massflow is maintained by adjusting pressure drop down to dp0. When Dp is below dp0, linear (laminar) flow is assumed and requested massflow is nolonger maintained. M = mmin * Dp/dp0 Flow control can also be turned off by giving a negative control signal (less than -0.5), in which case M = mmax * Dp/dp0. Heat resistance between liquid and air is divided into two fractions (we assume that convection to air dominates over radiation to zone surfaces): rTot = rFin + rAir. The corresponding temperature differences are related: TLiq - TSurf rFin ------------ = ---- TSurf - TAir rAir 990407 MV Long wave radiation behind the device it changed from Tx**4- Ty**4 to ABS((Tx**2+Ty**2)*(Tx+Ty)) * (Tx-Ty) to help solver. Problems have occured displacement ventilation. 981006 MV MassFlow equation is changed 980511 AB hFin replaced by kFin = fin res/total res. 980508 AB Check that hFin large enough compared to total transmission between air and liquid. 980506 MV MassFlow calc is changed 980225 MV Dp > Dp0 is added in massflow calc 970922 MV ExpLoc assigment is changed to avoid dividion by zero " EQUATIONS /* water heat balance */ P := M * cp_liq * (TOut - TIn); /* liquid to surface heat balance */ TLiq := TSurf + (TSurf - TAir) * kF_A; dT := TAir - TLiq; /* total absorbed heat*/ P = IF dT < 1. THEN k*length*dT ELSE k*length*dT**n END_IF; ExpLoc := -(TOut-TIn)/dT; TOut = TAir - (TAir - TIn) * IF M > 0 THEN IF ExpLoc > -0.01 THEN EXP(-0.01) ELSE_IF ExpLoc < -5 THEN EXP(-5) ELSE EXP(ExpLoc) END_IF ELSE 0.01 END_IF; /* front - back heat balance*/ P = Qfront + Qconv + Qwall; Qwall = IF LINEARIZE(1) THEN 5*area*(Twall - Tsurf) ELSE_IF hback >= 0. THEN /* given heat transfer coeff */ hback*area*(Twall - Tsurf) ELSE /*radiation only*/ eLW * BOLTZ * area * ABS(((Tsurf - ABS_ZERO)**2 + (Twall - ABS_ZERO)**2)* ((Tsurf - ABS_ZERO) + (Twall - ABS_ZERO))) * (Twall - Tsurf) /* eLW * BOLTZ * area * ((Twall - ABS_ZERO)**4 - (Tsurf - ABS_ZERO)**4) */ END_IF; /* water massflow*/ Dp := P1 - P2; M = IF DpOk > 0.5 OR (Dp > dp0 AND Contr > -0.5) THEN mmax*Contr + mmin*(1 - Contr) ELSE_IF Contr > -0.5 THEN mmin * Dp/dp0 ELSE mmax * Dp/dp0 END_IF; /* saturated modes */ DpOk := IF Event(G0, Dp - dp0) > 0 AND Contr > -0.5 THEN 1 ELSE 0 END_IF; LINKS TQ Front Tsurf, POS_IN Qfront; TQ BackConv Tair, POS_IN Qconv; TQ BackWall Twall, POS_IN Qwall; PMT Inlet P1, POS_IN M, Tin; PMT Outlet P2, POS_OUT M, Tout; ControlLink Control Contr; T AirTemp Tair; VARIABLES Temp dT LOC 10 ABS_ZERO BIG "Air-to-surface temp difference" Temp Tair IN 26 ABS_ZERO BIG "Surrounding air temperature" Temp Tsurf OUT 17 ABS_ZERO BIG "Average surface temperature" Temp TLiq LOC 16 ABS_ZERO BIG "Average liquid temperature" HeatFlux P LOC 90 0 BIG "Total absorbed heat" MassFlow M OUT 0.005 0 BIG "Water massflow" Temp Tin IN 15 ABS_ZERO BIG "Supply water temperature" Temp Tout OUT 15.5 ABS_ZERO BIG "Leaving water temperature" HeatFlux Qfront IN 58 -BIG BIG "Radiative and convective heat absorbed by panel front" HeatFlux Qconv OUT 30 -BIG BIG "Remaining convective heat absorbed" HeatFlux Qwall OUT 2 -BIG BIG "Heat absorbed from wall behind panel" Temp Twall IN 24 ABS_ZERO BIG "Surface temp of wall behind" Pressure Dp LOC 600 0 BIG "Panel and valve total pressure drop" Pressure P1 IN 600 0 BIG "Pressure at water inlet" Pressure P2 IN 0 0 BIG "Pressure at water outlet" Control Contr IN 0.5 -BIG 1 "Controller input 1 -> mmax, 0 -> mmin, -1 turns off control action" GENERIC G0 A_S 1 " " GENERIC DpOk A_S 1 "Mode memory, = 0 for linear behavior, = 1 for controlled" GENERIC ExpLoc LOC -0.03 -BIG BIG "Value inside function call EXP(), itroduced as a safety card" PARAMETERS GENERIC k S_P 4.18 SMALL BIG "Powerlaw coefficient in W/(m Deg-C**n)" Factor n S_P 1.28 SMALL BIG "Powerlaw exponent" Length strip_w S_P .5 SMALL BIG "Width of panel strip" Length length S_P 1 SMALL BIG "Total panel length" HeatCapM cp_liq S_P 4187 SMALL BIG "Liquid specific heat" HeatCond hback S_P 4 -BIG BIG "Heat transfer coefficient between panel and wall. If a negative value is given, pure radiative exchange is assumed" Factor kFin S_P .2 0 0.5 "Fin resistance / Total ditto" Factor eLWRad S_P .9 -BIG 1.0 "Panel back emissivity, for hback < 0" Factor eLWWall S_P .9 -BIG 1.0 "Wall long wave emissivity, for hback < 0" Pressure dp0 S_P 10 SMALL BIG "Pressure drop under which waterflow is nolonger maintained" MassFlow mmax S_P 0.01 SMALL BIG "Water massflow at Contr = 1 and Dp > dp0" MassFlow mmin S_P 1.E-4 SMALL BIG "Water massflow at Contr = 0 and Dp > dp0" Factor eLW C_P .8 0 1.0 "Long wave emissivity" Area area C_P .5 SMALL BIG "Panel area" Factor kF_A C_P .25 0 1.0 "Fin resistance / Air ditto" PARAMETER_PROCESSING eLW := 1.0/( 1.0/eLWRad + 1.0/eLWWall - 1.0 ); area := strip_w * length; kF_A := kFin / (1 - kFin); END_MODEL