VALIDATION OF A TRNSYS SIMULATION MODEL FOR PCM ENERGY STORAGES AND PCM WALL CONSTRUCTION ELEMENTS H. Schranzhofer, P. Puschnig, A. Heinz, and Wolfgang Streicher, email: w.streicher@tugraz.at, internet:http://www.iwt.tugraz.at
Outline 1) PCM storage model for TRNSYS a) Theoretical approach b) Model validation - PCM slurry storage (IWT measurement data) - Cylindrical PCM modules (IWT measurement data) - with paraffin - with sodium acedat - with sodium acedat + graphite c) Conclusion and outlook 2) PCM wall model for TRNSYS a) Theoretical approach b) Results for a test case
Phase Change Materials (PCM) 500 water paraffin (Sasol 6805) SA SA+graphite H - H 50 C [kj / liter] 400 300 200 100 0 ΔH = 396 [kj/liter] ΔH = 229 [kj/liter] ΔH = 183 [kj/liter] ΔH = 84 [kj/liter] -100 ΔT = 20 [ C] 20 30 40 50 60 70 80 temperature [ C]
Type 240: PCM storage model One-dimensional multi-node model for fluid Enthalpy approach (continuous material properties) 5 direct in- / outlets and/or 5 internal heat exchangers PCM modules - Cylindrical rods: 2D-heat conduction - Packed sphere beds: 1D-heat conduction - PCM plates: 2D-heat conduction PCM Slurry as storage / transfer medium Type implemented into Trnsys 16 i = N h, T i i m i i = 2 i =1 PCM UA i m, h, T PCM PCM PCM ik ik ik k = 1 k = n r
PCM Slurry enhancement of storage capacity Speicherkapazität (relativ zu Wasser) 1,80 1,70 1,60 1,50 1,40 1,30 1,20 1,10 50 % 40 % 30 % 20 % 10 % 1,00 50-85 50-80 50-75 50-70 50-65 50-60 50-55 Temperaturbereich [ C]
Storage Temperatures [ C] 75 70 65 60 55 50 Water storage discharge via internal HX Experiment Simulation Type 240 Tin = 50 C 500 [ / ] m& = kg h 45 0 20 40 60 80 100 120 140 160 180 Time [min] WATER Experiment Simulation Type 240 T 1 T 2 T 3 T 4 WATER 0 20 40 60 80 100 120 140 160 180 0 Time [min] α = ξ Gr 1 4 1000 800 600 400 200 heat transfer coefficient α [W/m 2 K]
storage temperatures [ C] 75 70 65 60 55 50 PCM Slurry discharge via internal HX 20% PC-SLURRY Experiment Simulation Type 240 Tin = 50 C [ kg h] m& = 500 / 45 0 20 40 60 80 100 120 140 160 180 Time [min] T 1 T 2 T 3 T 4 α = ξ Experiment 20% PC-SLURRY Simulation Type 240 Gr 1 4 0 20 40 60 80 100 120 140 160 180 0 Time [min] 1000 800 600 400 200 heat transfer coefficient α [W/m 2 K]
Cylindrical modules: storage geometry modules tank 100 cm 90 cm PCM filling ratio: 30% 5 cm 21 cm
Cylindrical modules paraffin material properties H [kj/kg] 500 450 400 350 300 250 200 150 100 50 0 0 20 40 60 80 100 λ PCM = 0.2 [ W / mk] ρ PCM 824 kg / m 3 = dc dmodule λ Cont = 0.2 [ W / mk] ρ Cont 910 kg / m = 50[ mm] =1.8[ mm] paraffin polypropylen 3 = cpcont, = 1800 / [ J kgk] temperature [ C]
Cylindrical modules paraffin charge power 5.5 5.0 110 100 4.5 T inlet 90 Power [kw] 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 TRNSYS (Type240) EXP losses m dot 80 70 60 50 40 30 20 10 T [ C] / Mass flow rate [kg/h] 0.0 0-0.5-10 0 20 40 60 80 100 120 140 160 180 200 Time [min]
75 70 Cylindrical modules paraffin temperatures, charging layer 1 (top) temperature [ C] 65 60 55 50 T = 70[ C ] inlet V & = 100 l / h [ ] 45 40 water: trnsys exp PCM (surface): trnsys exp PCM (center): trnsys exp 35 0 20 40 60 80 100 120 140 160 180 200 220 time [min]
75 70 65 layer 4 (bottom) Cylindrical modules paraffin temperatures, charging Tinlet = 70[ C] [ l h] V& = 100 / temperature [ C] 60 55 50 45 40 water: trnsys exp PCM (surface): trnsys exp PCM (center): trnsys exp 35 0 20 40 60 80 100 120 140 160 180 200 220 time [min]
5.5 5.0 Cylindrical modules paraffin: discharge power 110 100 4.5 T inlet 90 power [kw] 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 TRNSYS (Type240) EXP losses m dot 80 70 60 50 40 30 20 10 T [ C] / Mass flow rate [kg/h] 0.0 0-0.5-10 0 20 40 60 80 100 120 140 160 180 200 time [min]
75 70 layer 3 Cylindrical modules paraffin temperatures, discharging water: trnsys exp PCM (surface): trnsys exp PCM (center): trnsys exp temperature [ C] 65 60 55 50 45 0 20 40 60 80 100 120 140 160 180 200 220 time [min] Tinlet = 50[ C] [ l h] V& = 100 /
75 70 layer 1 (top) Cylindrical modules paraffin temperatures, discharging water: trnsys exp PCM (surface): trnsys exp PCM (center): trnsys exp temperature [ C] 65 60 55 50 45 0 20 40 60 80 100 120 140 160 180 200 220 time [min] Tinlet = 50[ C] [ l h] V& = 100 /
Cylindrical modules SA material properties 600 500 λ PCM = 0.5 [ W / mk] ρ PCM 1350 kg / m 3 = λ Cont = 0.2 [ W / mk] ρ Cont 910 kg / m 3 = H [kj/kg] 400 300 200 cooling heating dc dmodule cpcont, = 1800 / = 50[ mm] =1.8[ mm] [ J kgk] 100 0 0 20 40 60 80 100 temperature [ C] SA polypropylen
Modelling of subcooling effects Case 1: cooling 700 600 cooling heating 500 T critical_1 400 q [kj/kg] 300 200 100 0 0 20 40 60 80 100 T [ C] 1 PCM-temperature < T critical_1 cristallisation switch to red function
Modelling of subcooling effects Case 2: heating 700 600 500 cooling heating T critical_2 400 q [kj/kg] 300 200 100 0 0 20 40 60 80 100 T [ C] all PCM-temperatures > T critical_2 no cristallisation seeds left switch to blue function
Modelling of subcooling effects example: cooling 700 600 cooling heating T 4 T 3 T 2 T 1 500 q [kj/kg] 400 300 200 100 0 0 20 40 60 80 100 T [ C] Node 1 Node 2 Node 3 Node 4 time = n time= n +1 54.0 58.4 53.0 58.4 52.0 58.4 49.5 58.4 Module Module
Cylindrical modules SA discharge Power 2.4 120 2.0 100 Power [kw] 1.6 1.2 0.8 0.4 TRNSYS (Type240) EXP losses T inlet m dot 80 60 40 20 T [ C] / Mass flow rate [kg/h] 0.0 0 0 40 80 120 160 200 Time [min]
75 Cylindrical modules SA temperatures, discharging layer 4 (bottom) temperature [ C] 70 65 60 55 water: trnsys exp PCM (surface): trnsys exp PCM (center): trnsys exp 50 45 0 60 120 180 240 300 360 420 480 540 time [min] Tinlet = 50[ C] [ l h] V& = 100 /
Cylindrical modules SA+gr material properties 500 λ PCM = 4.5 [ W / mk] λ Cont = 15 [ W / mk] H [kj/kg] 400 300 200 ρ PCM 1054 kg / m 3 = dc dmodule ρ Cont 8000 kg / m = 53[ mm] =1.5[ mm] 3 = cp, cont = 477 / [ J kgk] 100 SA+gr 0 0 20 40 60 80 100 temperature [ C] stainless steel
Cylindrical modules SA+gr discharge Power 3 120 2.6 100 power [kw] 2.2 1.8 1.4 1 0.6 Psim Ploss mdot_in power Tinlet 80 60 40 T [ C] / mass flow rate [kg/h] 0.2 20-0.2 0-10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 time [min]
Cylindrical modules SA+gr temperatures, discharging layer 4 (bottom) 70 temperature [ C] 65 60 55 Twater (exp) Twater (exp) Tpcmsurface (exp) Tpcmcenter (exp) Twater (sim) Tpcmsurface (sim) Tpcmcenter (sim) 50 45 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 time [min] Tinlet = 50[ C] [ l h] V& = 100 /
Conclusions and outlook Simulation results correspond well to measurements for slurries and pure PCM. Current approximate approach of subcooling will be improved PCM-Graphite mixtures need more work Type 240 will be included simulation boundary conditions (building, user load, climate, hydraulics) according to IEA SHC Task 32 Expansion to ice storage is on the way
Theoretical approach Wall construction: 2.5 [cm] external plaster / 38 [cm] brick / 1.5 [cm] PCM plaster room with Ambient air External wall room PCM plaster Type 56 q s,2 q s,1 direct contact zone T s,2 T s,1 Type 56 air zone TRNSYS Model Type 241
Geometry of the test room IW1 Exterior wall construction 1.5 cm plaster / 38 cm brick / 1.5 cm PCM-plaster 1.5 cm PCM-plaster Interior wall construction west A F = 1.50 m 2 A = 20 m 2 AC day = 0.5 h -1 AC night = 6.0 h -1 1.5 cm plaster / 12 cm brick / 1.5 cm PCM-plaster Floor / Ceiling construction 2 cm parquet floor / 6 cm mineral wool / 18 cm concrete / 1.5 cm PCM-plaster EW A F = 2.25 m 2 EW south
Thermophysical properties Enthalpy [kj/kg] 50 45 40 35 30 25 MaxitClima plaster c p = 1 [kj/kgk] ΔT = 23 C c p = 1 [kj/kgk] ΔH = 18 [kj/kg] A F = 1.50 m 2 EW Asurface dpcm IW1 1.5 cm PCM-plaster A = 20 m 2 AC day = 0.5 h -1 AC night = 6.0 h -1 A F = 2.25 m 2 70.25 m EW 2 = = 1.5[ cm] 20 15 20 21 22 23 24 25 26 27 28 29 30 Temperature [ C] Δ Q = total Δ T = 3.0[ K] 7.06[ kwh] 2 353[ Wh / m ]
Simulation results Operative room temperature [ C] 30 29 28 27 26 25 24 23 22 21 20 1.5 cm gypsum plaster 1.5 cm PCM plaster 5280 5328 5376 5424 5472 5520 5568 5616 5664 5712 Hour of year
Conclusion and outlook First simulation results look realistic Comparison of simulation to measurement data will be performed (measurement data is welcome) The type will be used at IWT for building simulation projects Other beta testers are welcomes
Acknowledgment Project Energiesysteme der Zukunft of the Austrian Ministry for Traffic, Innovation and Technology. European project ENK6-CT2001-00507 (Phase Change Material Slurries) Task32 of the Solar Heating and Cooling programme of the International Energy Agency Task 32 Storage