REDUCING THE ENERGY CONSUMPTION IN BUILDINGS BY INCORPORATING MICROENCAPSULATED PCMS IN RIGID POLYURETHANE FOAMS

Transcription

1 Institute of Chemical and Environmental Technology Chemical Engineering Department University of Castilla La Mancha Ciudad Real, Spain REDUCING THE ENERGY CONSUMPTION IN BUILDINGS BY INCORPORATING MICROENCAPSULATED PCMS IN RIGID POLYURETHANE FOAMS Manuel Salvador Carmona Franco Ana María Borreguero Simón Beatriz Talavera Almena Ángel Serrano Casero Ignacio Garrido Sáenz Juan Francisco Rodríguez Romero

2 INTRODUCTION. THERMAL ENERGY STORAGE MATERIALS Petroleum 50 years Energy sources RENEWABLE Carbon 330 years Solar Energy 5000 millions of years Nuclear Fission 1 Million of years Uranium reactors 1000 years Development of new systems for saving energy Use of new renewable energy sources CLEAN SOLAR ENERGY UNIVERSAL IT NEEDS TO BE STORED! A PCM is a substance with a high heat of fusion which, melting and solidifying, is able to absorb and store or release large amounts of energy. ABSORB STORE RELEASE Wide variety of PCMs can be used: Inorganics ( hydrated salts) Organics (alkanes, paraffin, waxes)

3 INTRODUCTION. HOW DO PCMS WORK? HOT OUTSIDE COLD OUTSIDE Heat Required Heat Released BUILDING INSIDE External T > Melting T PCM becomes liquid (Heat required) BUILDING INSIDE External T < Freezing T PCM solidifies (Heat released) Properties of PCMs for applications in buildings: Melting temperature about 25ºC High latent heat Low cost Good availability. Non-toxic Non-corrosive

4 INTRODUCTION. PCMs INCORPORATION IN BUILDINGS Building systems for PCMs incorporation Wallboards, ceilings and floors Shutter of windows Cooling and heating systems SHELL CORE Ways of PCMs incorporation Direct incorporation PCMs microencapsulation

5 INTRODUCTION. PCMs INCORPORATION IN BUILDINGS Avoid loosing the PCM. Avoid interactions between PCMs and the rest of building materials. Safe handling of PCMs. Handling liquids as solid. Increase the area of heat transfer.

6 INTRODUCTION. MICROENCAPSULATION OF PCMs Spray drying technique Feed Gas for solvent evaporation Gas + solvent Product Suspension polymerization

7 Intensity (u.a.) Intensidad (u.a.) INTRODUCTION. MICROENCAPSULATED PCMs PROPERTIES Scanning Electron Microscopy (SEM) Low Angle Laser Light Scattering (LALLS) msd-(ldpe-eva-rt27) H H f =85,81J/ f J/g g H f =200.2J/g H f J/g Microcapsule Pure paraffin Differential Scanning Calorimetry (DSC) -1-2 H H f =85,81J/g f =96,7 H f =85,6J/g H f =96,2 J/g Material Original After thermal treatment Temperatura (ºC) Temperature (ºC)

8 OBJETIVE. WHY USE PCMs IN BULDINGS? EU directive 2010/31/UE: Directive on Energy Performance of Buildings - Buildings are responsible for 40% of energy consumption and 36% of CO 2 emissions in the Europe Community. - Energy performance of buildings is key to achieve the EU Climate and Energy objectives. Development of buildings with a more efficient use of energy Reduction of Energy consumption in heaters and air conditioners Environmental pollution Money spent in energy

9 OBJETIVE. INCORPORATION OF PCMs IN BUILDINGS MATERIALS The aim of this work is to develop sandwich panels exhibiting high TES capacity SANDWICH PANELS POLYURETHANE FOAMS EPOXI RESINS EXTERNAL SHEET RESIN CORE (POLYURETHANE FOAM)

10 EXPERIMENTAL PROCEDURE. FOAM SYNTHESIS Polyisocyanate Polyol Polyurethane n O=C=N-R N=C=O + n HO-R -OH [-CO-NH-R NH-CO-O-R -O-] n Polyol PCMs Polyisocyanate Additives (blowing agent, surfactant and catalyst) Mix Different microencapsulated PCMs contents Microcapsules distribution Latent Heat Foam structure and cell size Density Mechanical resistance

11 EXPERIMENTAL PROCEDURE. THERMAL ANALYSIS Experimental set up for thermal characterization 1. Rotameter 2. Signal Transmitter 3. Computer for data recording 4. Peristaltic Pump 5. Thermostatic Bath 6. Termocouples 7. Isothermal Chamber 8. Insulating Structure

12 3 cm EXPERIMENTAL PROCEDURE. THERMAL ANALYSIS THERMOCOUPLES DISTRIBUTION Upper Tª Middle Tª Upper Tª Middle Tª HEAT FLUX SENSORS DISTRIBUTION Plate Tª 10 cm Plate Tª Sensor Q side Sensor Q out Sensor Q in Flow Direction Flow Direction Sensor Q side

13 EXPERIMENTAL PROCEDURE. THERMAL ANALYSIS Modulated Differential Scanning Calorimetry (MDSC)

14 EXPERIMENTAL PROCEDURE. MECHANICAL RESISTANCE Mechanical characterization Uniaxial compression tests were performed according to ASTM D1621 (Standard Test Method for Compressive Properties of Rigid Cellular Plastics) Compression Experimental Set up

15 RESULTS AND DISCUSSION. SYNTHESIZED PU FOAMS Microcapsules Content (%wt) Rising Rate Final Foam Height Foam system viscosity

16 Density (kg/m 3 ) RESULTS AND DISCUSSION. DENSITY Zone 1 Zone % 10% 15% 20% % PCM 30% 40% 50% Microcapsules Content (%wt) Density Density > 30kg/m 3 (UNE 92120) (pren )

17 Intensity (u.a) RESULTS AND DISCUSSION. DSC ANALYSIS 0-0,05-0,1-0,15-0,2-0,25 0% Middle 10% Middle % PCM Q DOWN Q MIDDLE Q UP Q EXP Q TH (J/g) (J/g) (J/g) (J/g) (J/g) ,46 7,014 7,77 7,41 8, ,57 15,82 16,71 16,37 17, ,49 25,44 24,57 25,50 25, ,52 33,82 32,9 34,41 34, ,21 40,57 37,31 39,03 42,91-0,3-0,35-0,4 H f =40.57 J/g T=23.5ºC 20% Middle 30% Middle 40% Middle 50% Middle Q theoretical Q (J/g) microcápsules (J/g) microcapsules mass(g) Foam Weight (g) -0, Microcapsules Content (%wt) Temperature (ºC) Latent Heat Q experimental 3 i 1 3 i 1 Q V i i i V i i Microcapsules were homogeneously distributed into the whole foam

18 RESULTS AND DISCUSSION. CELL STRUCTURE AND SIZE SEM photographs of PU foams with different microcapsules content 0% 10% 20% 30% 40% 50% RPU are formed with microcapsules into the strut and also the cell wall

19 Specific Compressive Strength S (Mpa/(g/cm3)) Specific Compressive Modulus E (Mpa/(g/cm3)) RESULTS AND DISCUSSION. COMPRESSION TESTS Uniaxial compression tests were performed according to ASTM D1621 Specific compression strength and modulus for excluding the density effect % PCM % PCM No significant difference between the values of foams containing 0 to 20wt% Sharp decrease in the mechanical resistance for contents higher than 20wt% S=0.2-8 MPa/g/cm 3 y E=2-200MPa/g/cm 3

20 Temperature (ºC) RESULTS AND DISCUSSION. THERMAL ANALYSIS 1. Influence INTRO- of Temperature DUCCIÓN Experimental variation of temperatures at different points in a RPU foam without PCM 2. OBJETIVOS 40 T bath change in step 18 to 40ºC 3. PROCEDI- MIENTO EXPERIMENTAL 4. RESULTADOS T down1 =T down2 T middle1 =T middle2 T up1 =T up2 Tdown2 Tup2 Tbath Tup1 Tenvironment Tmiddle2 Tdown1 Tmiddle1 Tinsulation 5. CONCLU- SIONES t (s) Termocouples opposite to the flow One dimensional flow with the same temperature profile

21 Q (W/m 2 ) Temperature (ºC) RESULTS AND DISCUSSION. THERMAL ANALYSIS 40 Hot Plate Temperature Microcapsules Content (%wt) Tdown average 0% Tdown average 10% Thermal Damping Slope of the curves This behavior is more clear with percentages higher than 20% Tdown average 20% Tdown average 40% Tdown average 50% Tbath 140 Input Heat Flux 15 Down Temperature t (s) q in 0% (W/m2) q in 10% (W/m2) q in 20% (W/m2) 80 q in 30% (W/m2) Microcapsules Content (%wt) 60 q in 40% (W/m2) q in 50% (W/m2) Input heat Flux Maximum energy absorb or lower insulating effect t (s)

22 Q (W/m 2 ) Temperature (ºC) RESULTS AND DISCUSSION. THERMAL ANALYSIS 40 Hot Plate Temperature Tup average 0% 35 Tup average 10% Tup average 20% Similar temperatures at stationary condition, but 30 3 cm in thickness Tup average 30% Tup average 40% Tup average 50% big difference in the transition step 25 Tbath Melting of PCM by energy absorption 20 Output Heat Flux 15 External Temperature t (s) q out 0% (W/m2) q out 10% (W/m2) -4 q out 20% (W/m2) Microcapsules Content (%wt) q out 30% (W/m2) -6 q out 40% (W/m2) Output heat Flux -8 q out 50% (W/m2) Ability to store energy t (s)

23 Q (W) RESULTS AND DISCUSSION. THERMAL ANALYSIS Influence of Heat Flows Accumulation curves as a function of time and the percentage content of PCMs 0,9 0,8 0,7 0,6 0,5 Accumulated (W) 0% Accumulated (W) 10% Accumulated (W) 20% Accumulated (W) 30% Accumulated (W) 40% Accumulated (W) 50% 0,4 0,3 0,2 Total energy absorbed during one step temperature change 18ªC-40ªC 0,1 0-0, t (s) Microcapsules Content (%wt) THERMAL ENERGY STORAGE (TES)

24 Thermal Capacity Cp (J/g ºC) Thermal Conductivity K (J/m s) RESULTS AND DISCUSSION. THERMAL ANALYSIS Determination of thermal conductivity and heat capacity 10 0,100 Heat Capacity Cp 9 8 y = 0,0007x + 0,0541 0,090 c p = m probeta q ac T f T i 7 6 y = 0,0548x + 2,8559 0,080 0, ,060 Thermal conductivity K 3 0,050 κ = Q inlet Δx ΔT 2 1 Cp(J/g C) K (J/m s) 0, % PCM 0,030 Cp and K follow a straight line (0.05 and respectively) Both are representative of those reported in the literature

25 RESULTS AND DISCUSSION. THERMAL APPLICATIONS Standar Room 3x4x2.5 m 3 1 m 3 panels of RPU (thickness of 3cm) Foam (% PCM) TES (kwh/m 3 ) Panels of RPU

26 RESULTS AND DISCUSSION. THERMAL APPLICATIONS As example Consumption of a 60 Watt light bulb = 1.44kWh Energy saved by a room covered with panels containing 50% of microcapsules Energy spent by 4 light bulbs working all the day Centro Nacional de la Energía (CNE) CO 2emitted = 0.35kg/KWh

27 REDUCING THE ENERGY CONSUMPTION IN BUILDINGS BY INCORPORATING MICROENCAPSULATED PCMS IN RIGID POLYURETHANE FOAMS THANK YOU FOR YOUR ATTENTION Reducing the energy consumption in buildings by incorporating microencapsulated PCMs in rigid polyurethane Título foams presentación

28 CONCLUSIONS - It is possible to incorporate up to a 50wt% of msd-(ldpe-eva-rt27) into the PU foams, achieving a homogeneous distribution of the microcapsules and improving the TES capacity of the foams. - The higher the microcapsules content, the lower the final foam height. Moreover, the foam density increases with this content. - Microcapsules are mechanically stable and they can be found into the strut and also on the cell wall. - The higher amount of microcapsules inside the building materials, the higher is the TES Capacity. - Thermal capacity and the thermal conductivity follow a straight line, increasing of 0,055 and 0,0007 respectively. - The incorporation of a 50 wt% of PCMs allows to save up to 5.38KWh/m 3, equivalent to 1.44kWh equivalent to the spent energy by 4 light bulbs working all day. - The incorporation of the msd-(pebd EVA-RT27) into conventional housings will show a great decrease in the energy consumption and thus in the CO 2 emissions.