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Plaster as Thermal Energy Storage Composite
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Technologies and Materials for Renewable Energy, Environment and Sustainability, TMREES18, 19–21 September 2018, Athens, Greece Technologies and Materials for Renewable Energy, Environment and Sustainability, TMREES18, 19–21 September 2018, Athens, Greece 15th International Symposium onas District HeatingEnergy and Cooling Paraffin/The Expanded Perlite/Plaster Thermal Storage
Composite Paraffin/ Expanded Perlite/Plaster as Thermal Energy Storage Assessing the feasibility of using the heat demand-outdoor Composite a Najoua Mekaddem Samia Ben Alia, Magali Foisb,heat Ahmed Hannachiforecast temperature functiona*,for a long-term district demand Najoua Mekaddem *, Samia Ben Ali , Magali Fois , Ahmed Hannachi I. Andrić *, A. Pina , P. Ferrão , J. Fournier ., B. Lacarrière , O. Le Corre
a b Engineering, National Engineering a Laboratory of Engineering Processes and Industrial Systems, Departmenta of Chemical – Processes School a,b,c a a b c c of Gabes,University of Gabes, Street Omar Ibn El Khattab,Gabes 6029,Tunisia a bStudies and Research Center in Thermal, Environment and Systems, University Paris-Est, 61 Av.General de Gaulle 94010, Creteil Cedex, Laboratory of Engineering Processes and Industrial Systems, Department of Chemical – Processes Engineering, National Engineering School a IN+ Center for Innovation,of Technology and Policy Research - Instituto Superior Técnico, Av.6029,Tunisia Rovisco Pais 1, 1049-001 Lisbon, Portugal France Gabes,University of Gabes, Street Omar Ibn El Khattab,Gabes b b Recherche & Innovation, 291 Avenue Dreyfous Daniel,61 78520 Limay, France Studies and Research CenterVeolia in Thermal, Environment and Systems, University Paris-Est, Av.General de Gaulle 94010, Creteil Cedex, c Département Systèmes Énergétiques et Environnement - IMT Atlantique, 4 rue Alfred Kastler, 44300 Nantes, France France a
Abstract Abstract Abstract The use of thermal energy storage composite materials allows passive cooling and heating in buildings, yielding
substantial energy savings. The purpose of this study is to develop and test a new phase change material (PCM) District networks are storage commonly addressed in the literature as one the most effective solutions forleakage decreasing the The use heating of by thermal energy composite materials allows passive cooling and heating in buildings, yielding composite loading expanded perlite (EP) with paraffin (RT27) to ofform plaster composites. The tests greenhouse gas emissions from theRT27 building sector. These systems require high investments returned through the heat substantial savings. The purpose of thisrate. study isavoid to develop andleakage test a new phase change material (PCM) allowed to energy unfold the optimal loading To paraffin out which of theare composite structure, a sales. Due by to the changed climate conditions and building policies, heat demand in mixing the future decrease, ® perlite composite loading expanded (EP)used with to form plaster composites. The leakage tests (SL), was toparaffin coat renovation the(RT27) RT27/EP composite before it could with plaster. waterproof product, Sikalatex prolonging the investment return period. allowed to unfold the optimal RT27 loadinginrate. To were avoidassessed. paraffinThe leakage of the composite structure,ona Thermal properties of RT27/EP/SL integrated plaster effectout of aluminum powder insertion The main scope of this paper is to® assess the feasibility of using the heat demandcomposite – outdoor temperature function heatplaster. demand (SL),properties, was used was to coat the RT27/EP before it for with waterproof product, Sikalatex enhancing the composite thermal investigated. Paraffin loading ratemixing was 60% by direct forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of on 665 Thermal properties RT27/EP/SL in plaster composites were assessed. The effect aluminum powder insertion impregnation. FTIRofanalyses provedintegrated that the produced showed a goodofchemical compatibility between buildings that vary in both construction period and typology. Three weather scenarios (low, medium, high) and three district enhancing the composite properties, investigated. Paraffin energy loadingstorage rate was 60% ofby51.57 direct different components. DSC thermal analyses(shallow, revealed thatwas composites have suitable capacities ± renovation scenarios were developed intermediate, deep). To estimate the error, obtained heat demand values were -1 proved that the produced composites showed a good chemical compatibility between impregnation. FTIR analyses for RT27/EP/SL and RT/EP/SL/Al, respectively. 0.01 and 49.95 ±0.15 kJ.kg compared with results from a dynamic heat demand model, previously developed and validated by the authors. different components. DSC analyses revealed that composites haveThermal suitablecycling energy tests storage capacities of 51.57 ± These composites suitable for indoor temperature regulation. showed a good thermal The results showed are that when -1 only weather change is considered, the margin of error could be acceptable for some applications for RT27/EP/SL and RT/EP/SL/Al, respectively. 0.01 and 49.95 ±0.15 kJ.kg stability of plaster PCM composite. Thermal conductivity of plaster composite containing 50% wt of (the error in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation These composites are temperature Thermal cycling tests showed a goodconsidered). thermal RT27/EP/SL/Al composite wasfor increased by(depending 80% andregulation. 68% at 12°C andrenovation 40°C respectively compared with the scenarios, the error valuesuitable increased upindoor to 59.5% on the weather and scenarios combination stability of plaster PCM composite. Thermal conductivity of plaster composite containing 50% wt aluminum free composite. The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to of the RT27/EP/SL/Al composite was hours increased by 80% andthe 68% at 12°C 40°C respectively compared with the decrease in the number of heating of 22-139h during heating seasonand (depending on the combination of weather and © 2018 2019 The Thefree Authors. Published by Ltd. aluminum composite. © Authors. Published by Elsevier Elsevier Ltd. hand, function intercept increased for 7.8-12.7% per decade (depending on the renovation scenarios considered). On the other This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) coupled and scenarios). The values suggested could be scientific used to modify the of function parameters for the scenarios considered, and Selection peer-review under responsibility of the committee Technologies and Materials for Renewable Energy, © 2018 The Published by Elsevier Ltd. improve theAuthors. accuracy of heat demand estimations. Environment and Sustainability, TMREES18. © 2017 The Authors. Published by Elsevier Ltd. * Corresponding author. Tel.: +21650519474; fax: +0-000-000-0000 . Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and E-mail address: [email protected] Cooling. [email protected]
* Corresponding author. Tel.: +21650519474; fax: +0-000-000-0000 . E-mail address: [email protected] Keywords: Heat demand; Forecast; Climate change [email protected] 1876-6102 © 2018 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection peer-review under responsibility of the scientific 1876-6102and © 2018 The Authors. Published by Elsevier Ltd. committee of Technologies and Materials for Renewable Energy, Environment and TMREES18. ThisSustainability, is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and©peer-review under responsibility the scientific 1876-6102 2017 The Authors. Published byofElsevier Ltd. committee of Technologies and Materials for Renewable Energy, Environment 1876-6102 © 2019TMREES18. The Authors. Published by Elsevier Ltd. and Sustainability, Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and Cooling. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsibility of the scientific committee of Technologies and Materials for Renewable Energy, Environment and Sustainability, TMREES18. 10.1016/j.egypro.2018.11.279
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This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsibility of the scientific committee of Technologies and Materials for Renewable Energy, Najoua Mekaddem et al. / Energy Procedia 157 (2019) 1118–1129 1119 Environment and Sustainability, TMREES18. Keywords: Composite; Latent heat energy storage; Phase Change Material; Porous material
1. Introduction Energy Storage Systems (ESS) have recently great attractive features to improve energy efficiency. Thermal Energy Storage (TES) involving latent heat and sensible heat storage or both of them becomes an alternative and a cheaper technique to reduce energy consumption and enhance the comfort level in buildings [1, 2]. Phase Change Materials (PCMs) are widely used as thermal energy storage materials for temperature control applications [3]. PCMs can be included in building structures in different ways, wallboards, ceilings and floors or incorporated into construction materials. The solar energy excess available in the off-peak time of sunshine hours can be stored in TES devices based on PCMs for later use in the night hours [4]. For this purpose, Kuznik and Virgone [5] evaluated the thermal performances of a PCM copolymer composite wallboard in a test room for a summer day, a winter day and a mid season day. As results, they found that the overheating effect was reduced, the energy stored at high temperature was liberated to air room when the temperature minimum was reached. Also, the human thermal comfort is improved by radiative heat transfer and the natural convection is ameliorated by PCM, preventing thermal stratifications. Huseyin et al. [6] studied the performance of PCM storage unit during the charge and discharge periods for greenhouse heating. In comparison with the conventional heating, the solar air collector integrated with PCM created a 6-9 °C temperature variation between the inside and outside of the greenhouse, providing about 1823% of total daily thermal energy requirements of the greenhouse for 3-4 h. Gracia et al. [7] inspected the potential of PCM panels containing paraffin SP22, installed in ventilated facade to provide energy benefits during heating period under mediterranean-continental climate conditions. For the cold storage sequence, the cooling supply provided is limited to values below 12 MJ/day while free cooling can reach values above 150 MJ/day depending on the region. Yet, the cold storage sequence provided cooling during 3 or 4 h at cooling demand period. Kosny et al. [8] tested experimentally the thermal performance of two roof configurations; a control asphalt shingle roof and a PV-PCM roof/attic one. Results showed about 30% heating and 50% cooling load reductions for the PV-PCM roof/attic configuration compared to control asphalt shingle roof. Meanwhile, Researchers aim to find novel efficient and economical energy storage materials. They have investigated stabilized PCM composites and studied heat transfer enhancement techniques shape in order to have a great storage capacity. Foremost, it is essential to select suitable materials for preparing an appropriate PCM composite good thermal properties. This composite should maintain its solid shape even when PCM changes from solid to liquid state. The main methods to obtain stabilized shape or stable form of PCM composites are encapsulation by using shell materials [9, 10], polymerization techniques [11] and impregnation into organic or inorganic supports. Shell materials encapsulation and polymerization methods have high cost and complex manufacturing processes but incorporation method in porous matrices is simple and has a low processing cost [12]. Using porous structure materials as supports to obtain the stable PCM composite form is developing as perspective framework of heat storage materials [13]. Due to their abundance, low cost, high fire resistance and high porosity, porous material are appropriate supports to contain PCMs. Incorporating heat storage material into porous texture such as expanded graphite [14, 15], activated carbon [3], diatomite [16, 17] and expanded perlite [18, 19, 20] can be done by two ways, direct immersion or vacuum impregnation. Wei et al. prepared a stable PCM composite form containing fatty acids (Capric acid and capric-stearic acid) incorporated in an expanded perlite using the direct fusion adsorption method [21]. The PCM insertion rate was 50%wt. Latent heat values of CA/EP composites are 87.3 J.g-1 for the melting and 89.0 J.g-1 for the freezing processes. An appropriate binary paraffin blends/opal composite was developed by Sun et al. to be used as an indoor thermal energy storage [2]. Its phase transition temperature and latent heat were respectively 24.9 °C and 59 J.g-1. Khadiran et al [3] studied the preparation and thermal properties of n-octadecane activated carbon composite which showed a good thermal reliability even after several melting/freezing cycles. The amount of the loaded n-octadecane was 42.5 %wt. Karaman et al. [22] prepared
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a polyethylene glycol (PEG)/diatomite composite by vacuum impregnation. PEG was retained by 50 % wt into pores of diatomite without leakage. Zhang et al [20] produced a Capric Acid- Palmitic Acid/Expanded Perlite composite PCM using vacuum impregnation method. The composite was mixed with gypsum to obtain thermal-regulating gypsum board. The phase change temperature range of PCM composite was from 24 to 31°C, and its latent heat was 88.4 J.g-1. Several techniques have been used to enhance heat transfer rates of PCM composites such as embedding PCMs in highly conductive porous media like graphite or metal matrices [23], dispersing highly conductive particles within PCMs, multiple PCMs and microencapsulation of PCM [24, 25]. In some cases, depending on the insertion of the shape stabilized composite in buildings, it seems necessary to protect the composite against destruction which can be caused by interaction with surrounding materials, additional thermal stresses and vapor pressures caused by the volume change during phase transition [17]. Adding coating material to the PCM composite was adopted in few studies. As studied by Zhang et al. [27], after the impregnation process, to prevent leakage, the porous material loaded with PCM was treated by a slurry of latex and polymer modified cement for 5 min. During the impregnation/ encasement of PCMs in lightweight aggregates (LWAs), Kheradmand et al [28] tested four different coating solutions (Sikalastic-490T, Weber Dry, Lastic Makote3 and ECM-2) in order to obtain an adequate coating. Their results showed that the amount of leaked PCM from different composites under cooling/ heating cycles were only exceeding 0.5%. As described in literature, the encapsulation of paraffin wax RT27 was performed by coacervation and spraydrying [29], polymerization, emulsion polymerization [30] which are complex, expensive and difficult to be controlled [30, 31, 32]. Therefore, it is intended to develop a composite using simple technique and construction materials. Expanded perlite (EP) is widely used as an insulating material in construction. Despite its highly porous interne structure, low density, low cost and good thermal reliability [21], few studies have investigated it to elaborate thermal energy storage composites. The aim of this work is to obtain a new composite with a melting temperature between 20°C and 30°C appropriate to be included in building structures. The RT27 and expanded perlite are chosen to prepare a stable form heat energy storage plaster composite with good thermal properties. Using direct impregnation, the composite was prepared by loading paraffin RT27 into EP with a commercial coating material and inserted into plaster. To improve its thermal conductivity, an aluminum powder was added to the composite after drying the coating material. The effect of adding a coating material and a metal powder on the thermal performances of RT27/EP were analyzed. 2. Materials and methods 2.1. Materials Paraffin wax namely RT27 was chosen as thermal storage material. It has a melting temperature range of 25-28 °C which is close the ambient temperature human comfort. RT27 was kindly supplied by Rubitherm technologies GmbH. Paraffin is a mixture of solid saturated hydrocarbons with the molecular formula CnH2n+2(4% C17H32; 45% C18H34; 36% C19H36; 12% C20H38; 2% C21H40 and 1% other alkanes) [9]. Table 1 gives the relevant RT27 properties as reported by Rubitherm technologies GmbH. Table 1. Properties of RT27 as reported by Rubitherm GmbH Melting Area
25-28 °C
Specific heat capacity
2 kJ.kg-1.K-1
Heat storage capacity ±7.5% [20 °C 35 °C]
179 kJ.kg-1
Thermal conductivity
0.2 W.m-1.K-1
Density liquid at 40 °C
760 kg.m-3
Density solid at 15 °C
880 kg.m-3
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Expanded perlite (EP) was acquired from PERLA group Tunisia. The main chemical constituents of EP were determined using X-ray fluorescence spectrometer (XRF, JSX-3201Z) and are given in table 2. Sikalatex® (SL) is a resin water proof adherent that was purchased from Sika Group and used as coating material. Aluminum powder (Al) was supplied from Minerals-water Ltd and the plaster was obtained from Knauf-Meknassy-Tunisia. Table 2. Chemical composition of expanded perlite. Constituent
SiO2
Al2O3
Fe2O3
CaO
Na2O
K2O
MgO
Ratio%
74.3
12.6
2.7
1.0
3.4
6.0
0.1
2.2. Preparation of the paraffin/expanded perlite /Plaster composite The expended perlite was dried at 110 °C for 24h in order to eliminate moisture. The RT27 was heated to 40 °C. The dried expanded perlite (EP) was added at different rates to the melted paraffin. The mixture was stirred until the PCM was uniformly dispersed into the EP pores. The highest ratio of paraffin insertion in EP was determined by two leakage tests. The first test was realized after the impregnation process and carried for four hours. The second test was performed by maintaining the loaded EP at 40 °C for three days. In each case, the relative weight loss of the loaded EP is determined. Because of the hydrophilic character of the EP, when preparing plaster composite structures, paraffin may be displaced by water. To prevent paraffin leakage, the RT27 /EP composite was coated by polymer water proof Sikalatex®. The impact of adding an aluminum powder was investigated in 10%wt to enhance the thermal conductivity. Plaster boards were prepared by mixing the obtained PCM composite with gypsum and water. The gypsum powder and water were mixed and then the PCM composite was added at different mass fractions. For each fraction, the mixture was uniformly stirred until forming a homogeneous slurry which was poured into a 40mm*40mm*6mm mould. The mould was dried at room temperature. 2.3. Characterization techniques Fourier-transform infrared spectroscopy (FT-IR) was carried out by a Frontier, Perkin Elmer spectrometer between 500 and 4000 cm-1. The melting temperature, latent heat and heat capacity were measured by a Differential Scanning Calorimeter (Diamond DSC of Perkin Elmer) at 10 °C.min-1 between -30 °C and 60 °C. The thermal conductivity and thermal diffusivity were estimated simultaneously by the periodic method used at CERTES [33, 34]. The measurement principle of this method is to use a small temperature modulation in a parallelepiped-shape sample placed between two metal plates. The bottom plate temperature was controlled thanks to a Peltier module. The thermal stress imposed by this plate was a sum of five sinusoids for which amplitude and frequency were controlled. Heat transfer through the sample leads to a temperature variation in the upper plate. The thermal conductivity and diffusivity parameters were then calculated by inverse method from records of input and output temperatures' variations. 3. Results and discussion After producing the PCM composite material several tests and characterization techniques were conducted on the samples as described in previous section. 3.1. Leakage tests The leakage tests were carried out to study the ability of the EP pores to retain the PCM even when the composite was kept at temperature above the melting point. Different PCM loading rates ranging from 33% to 90%, were prepared and conditioned at 40 °C for four hours. A paraffin amount adhering the container walls was observed
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when the loading percent was high. These samples were also kept for three days in an oven at 40 °C. Significant paraffin amount can leak out of the composite material for paraffin loading percent higher than 60%. The first leakage test showed that for 33% and 50% there was no leakage observed, the paraffin was totally contained within the EP pores. But, trace amounts can be significant for paraffin loading percenteses higher than 60%. The second test revealed that for paraffin loading rate below 60% the leaked amount was insignificant. However, a considerable amount of seepage was found for the samples of 75% and 90%. Thus, that optimal RT27 loading rate is around 60% for which the paraffin would be confined to EP pores. The RT27 was successfully incorporated into the EP porous structure and the seepage could be avoided. These results give information regarding the loading capacity. The PCM loading percent of 60% was chosen as an optimum to prepare the PCM composite. 3.2. FTIR analyses of PCM composite FTIR analysis was carried out to identify possible chemical or physical interactions between different components of the composite. Fig. 1 shows FTIR transmission spectrum of characteristic peaks of RT27, EP, SL, plaster and their composites.
Fig. 1. FTIR spectrum of components and prepared composites
As reported in literature, paraffin wax has three characteristic transmission or absorption bands: rocking vibration of -CH2 at 721 cm-1, deformation vibration of -CH2 and -CH3 at 1466 cm-1, and three intensive peaks at 2852 cm-1, 2921 cm-1 and 2957 cm-1 which belong to alkyl stretching vibrations of -CH2 and -CH3, [12, 35, 36]. Expanded perlite spectrum presents a peak at 788 cm-1 that could be attributed to the stretching vibration of OH and a large one around 1021 cm-1 most probably corresponding to Si-O-Si asymmetric stretching vibration [37]. The bands for RT27/EP spectrum (Fig.1.a) are present without any shifting. FTIR spectrum confirmed that these bondings were not broken or changed during the RT27 incorporation process as reported by Chung et al. [35]. Thus, paraffin loading in the EP pores occurs without chemical reactions and is only driven by capillary and surface tension forces [38]. Similar result has been previously determined by other studies [38, 37]. As shown in Fig.1.b, the SL has a more complex structure, the peaks at 698 cm-1 and 758 cm-1 were attributed respectively to an out of plane bending and deformation vibrations of the CH groups in the aromatic rings [39]. Peak at 966 cm-1 could reflect an out of plan vibrations of CH groups near the double bond. Peaks at 1452 cm-1 and 1493 cm-1 may correspond to the stretching vibrations of the carbons in aromatic rings [39]. There is a strong peak at 2919 cm-1 which could be relevant to asymmetrical stretching vibrations of the CH2 groups and a broad one between 3115 and 3723 cm-1 probably corresponding to OH vibration [39, 40]. As reported by Munteanu et al. [39], the SL spectrum is consistent with copolymers used in sealants, coatings, waterproofing materials. In the RT27/EP/SL spectrum (Fig.1.b), no additional peaks were noticed. However, the large band between 3115 and 3723 cm-1 became less intensive. For the plaster spectrum (Fig.1.c), Sulfate ion bending modes vibrations occur at 596 cm-1 and 667 cm-1 and asymmetric stretching
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at 1104 cm-1 [41]. The peaks at 1622 cm-1 and 1685 cm-1 could be related to water bending vibrations. Mandal et al. [42] suggested to assign the two bands at 3404 cm-1 and 3528 cm-1 to OH stretching. As can be seen by adding the SL to the RT27/EP and inserting the obtained composite into plaster, did not lead to the appearance of new peaks in the FTIR spectrum of RT27/EP/SL/plaster. Thus, RT27/EP composite possess a good chemical compatibility with SL coating and plaster. 3.3. DSC analyses of PCM composite The DSC instrument used for thermal characterization was calibrated on enthalpy mode. The measurements were repeated to show reproducibility and avoid the effect of thermal history for each sample. Samples were set in aluminium solid pans and analyses were carried out at 10 °C.min-1 between -30 °C and 60 °C. Fig. 2 and Fig. 3 show DSC curves of pure paraffin RT27 and composites, respectively. As shown in Fig. 2, paraffin has two peaks. The major one corresponds to solid-liquid phase change. The minor peak corresponds to the solid-solid transition. From heating and cooling DSC analyses, melting and crystallization onset temperatures are very close at around 25 °C. The RT27 has a relatively high phase change melting/crystallization enthalpy of 154 ±2.3 kJ.kg-1. The measured specific heat capacities are 1.7 ±0.07 kJ.kg-1.°C-1 and 2.18 ±0.06 kJ.kg-1.°C-1 at solid and liquid states, respectively. The average heat storage capacity between 20 and 35 °C is 186.7 kJ.kg-1 which is close to the value provided by the manufacturer data sheet (table 1). The slight differences could be attributed to inherent experimental errors. In fact, in the literature much higher discrepancies were reported. This is due to the sensitivity of DSC measurements for which the results are affected by many factors such as structure and mass of sample, heating and cooling rate and the selected type and extremities of baseline, as mentioned by Trigui et al. [43]. The data extracted from DSC curves of RT27 and RT27/EP, RT27/EP/SL, RT27/EP/SL/Al composites are summarized in table 3 for heating and cooling processes. As expected, the specific heat storage capacity decreases with the decreasing RT27 content of PCM composite. The phase change melting and crystallization temperatures of composites (RT27/ EP, RT27/ EP/ SL and RT27/ EP/ SL/ Al) are slightly changed due to impregnation. This can be explained by some interactions or movements of paraffin molecules into interne porous structure of EP as previously reported by Karaipekli et al. [40]. Moreover, it is noticed that, when Al is added there is no significant effect on the melting and freezing onset temperatures (table 3). However, during the cooling process a clear new peak appeared at the tail of RT27 phase change when Al was incorporated. Latent heat storage capacities of produced composites were compared to those reported in the literature as shown in table 4. It is clear that RT27/EP/SL is well suited for air conditioning applications. Table 3. Latent heat energy storage properties of RT27 and prepared composites. Solid- liquid transition
Solid-solid transition
Samples
Tm (°C)
Tf (°C)
Average ΔHm (kJ.kg -1)
Tm (°C)
Tf (°C)
Average ΔHm (kJ.kg -1)
RT27
25.1
25
154.00 ±2.30
1.5
1.0
21.78 ±0.71
RT27/EP
26.3
25.5
84.00 ±0.50
2.6
0.9
10.61 ±0.61
RT27/EP/SL
26.3
25.8
51.57 ±0.01
2.3
1.4
6.43 ±0.32
RT27/EP/SL/Al
26.1
25.3
49.95 ±0.15
2.2
0.9
6.18 ±0.22
m: melting, f: freezing, t: transition
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Fig. 2. DSC heating and cooling curves of RT27 paraffin at 10°C.min-1
Fig. 3. DSC heating and cooling curves of RT27 paraffin and different composites at 10°C.min-1
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Table 4. Latent energy storage capacities of some PCM composites. PCM composites
Tm (°C)
Tf (°C)
ΔHm (kJ.kg-1)
Reference
PEG (50 wt%)/ diatomite
27.7
32.2
87.1
[22]
Capric-mystiric acid (55 wt%)/expanded perlite
21.7
20.7
85.4
[18]
N-octadecane (41.4 wt%)/activated carbon
28.0
27.6
95.4
[45]
RT21/ uncoated expanded perlite
17.2
24.3
35.5
[19]
RT21/ coated expanded perlite
16.3
24.6
60.9
[19]
RT27/EP
26.3
25.5
84.0
Present study
RT27/EP/SL
26.3
25.8
51.6
Present study
m: melting, f: freezing
Evaluating thermal characteristics of composite PCM integrated in a material construction like plaster is required. As shown in DSC results given in Fig. 4, the latent heat storage of RT27/EP/SL/plaster increases with the increasing RT27 content of the composite. The processing of the heat flow curve allowed to obtain the phase change latent heat for each prepared composite material. For 50% RT27/EP/Sl content, the latent heat was about 22.5 ±0.4 kJ.kg-1. To investigate the thermal reliability of RT27/EP/SL/plaster and RT27/EP/SL/Al/plaster as heating storage material, thermal cycling tests were performed and the corresponding DSC curves for 50% composite content in plaster before and after cycling are shown in Fig. 5. As can be observed, the two composites have a good thermal reliability, their curves are almost perfectly overlapping for the sample free of Al.
Fig. 4. DSC heating and cooling curves of PCM plaster composites at 10°C.min-1
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Fig. 5. DSC heating and cooling curves of PCM plaster composites with (a) and without (b) aluminum after 30 cycles (plaster content: 50%).
3.4. Thermal conductivity improvement The low PCM thermal conductivity could lead to heat transfer low rates, limiting the heat storage and retrieval capacity during the heating and cooling processes. Thus, increasing energy consumption to maintain the desired temperature [35]. Because our MCP composite has low heat conducting components, an aluminum powder was added after drying the RT27/EP/SL composite at 10 wt%. Thermal conductivity and diffusivity measurements were then carried out at 12 °C, at which no phase change is observed and at 40 °C when the RT27 would be at liquid state. The results are given in table 5. The thermal properties of each composite components were also added in the same table. At 12 °C and 40 °C, adding Al to the composite allowed to increase the thermal conductivity by 66% and 69%, respectively. The improvement in thermal conductivity was consistent and very important regardless of RT27 state. Compared to PCM composite without Al, the observed thermal diffusivity increase was about 200% and 67% for 12 °C and 40 °C, respectively. The measured thermal conductivity values of RT27/EP/SL inserted in plaster with and without aluminum for different plaster mass fractions are shown in Fig. 6. Compared to plaster, for composites free of Al, as RT27/EP/SL content increases, the thermal conductivity slightly decreases then reaches a maximum at 40% wt. This behavior was observed regardless of The RT27 state. In the literature similar conflicting results of thermal conductivity were reported [20]. The PCM incorporation in plaster could improve or deteriorate thermal conductivities of composites. However, when Al was added thermal conductivity increases with the decreasing plaster content. With the reduction in plaster content and the increase of aluminum composite content, the thermal conductivity of composites increased, especially when the RT27/EP/SL/Al fraction was higher than 20%. For high plaster contents exceeding 80%, adding Al does not improve very much composite thermal conductivity. The highest thermal conductivity improvement was obtained for plaster content of 50%. As shown in this Fig. 6, PCM plaster composite thermal conductivity was enhanced by 80% and 68% at 12 °C and 40 °C, respectively. Thermal diffusivity variation with plaster contents is presented in Fig. 7. As can be seen, the same evolution has been observed for 12 °C and 40 °C. The thermal diffusivity was enhanced by more than 30% when Al was added.
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Najoua Mekaddem et al. / Energy Procedia 157 (2019) 1118–1129 Najoua Mekaddem et al./ Energy Procedia 00 (2018) 000–000 Table 5. Thermal conductivities and diffusivities of components and prepared composites with and without aluminum at 12°C and 40°C. Samples
12 (°C)
40 (°C)
λ (W.m-1.K-1)
α (mm2.s-1)
λ (W.m-1.K-1)
α (mm2.s-1)
RT27
0.166 ±0.005
0.073 ±0.005
-
-
SL
0.167 ±0.003
0.102 ±0.003
0.187 ±0.009
0.093 ±0.007
RT27/EP/SL
0.149 ±0.015
0.112 ±0.008
0.176 ±0.014
0.153 ±0.015
RT27/EP/SL/Al
0.247 ±0.006
0.226 ±0.008
0.297 ±0.009
0.256 ±0.011
Fig. 6. PCM composite material thermal conductivities for different plaster contents at 12°C (a) and 40°C (b).
Fig. 7. PCM composite material thermal diffusivities for different plaster contents at 12°C (a) and 40 °C (b)
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11
4. Conclusion A stabilized shape composite was successfully prepared by paraffin RT27 impregnating into Expanded Perlite (EP). The maximum RT27 loading rate was 60 wt%. To prevent leakage, the RT27/EP was coated by water proof product, SikaLatex® (SL). The RT27/EP/SL composite was mixed with gypsum to obtain thermal regulating plaster composite. The plaster PCM composites were characterized by FTIR, DSC and periodic method for thermal properties's measurements. FTIR analyses confirmed the good chemical compatibility between all composite components. DSC analysis showed good thermal reliability and stability. No shifting of phase change and transition temperatures was observed. Thermal conductivities were improved by adding aluminum powder. In plaster composite, the thermal conductivity reached 0.47 W.m-1.K-1 for 50% wt RT27/EP/SL/Al content. The PCM plaster composite is suitable for regulating indoor temperature in buildings. Acknowledgements This project is carried out within the framework of a MOBIDOC doctoral thesis of the PASRI program financed by the EU and managed by the ANPR. References [1] Rathod, Manish K., and Jyotirmay Banerjee. “Thermal Stability of Phase Change Materials Used in Latent Heat Energy Storage Systems: A Review.” Renewable and Sustainable Energy Reviews 18 (2013): 246–58. [2] Sun, Zhiming, Weian Kong, Shuilin Zheng, and Ray L. Frost. “Study on Preparation and Thermal Energy Storage Properties of Binary Paraffin Blends/opal Shape-Stabilized Phase Change Materials.” Solar Energy Materials and Solar Cells 117 (2013): 400–407. [3] Khadiran, Tumirah, Mohd Zobir Hussein, Zulkarnain Zainal, and Rafeadah Rusli. “Encapsulation Techniques for Organic Phase Change Materials as Thermal Energy Storage Medium: A Review.” Solar Energy Materials and Solar Cells 143 (2015): 78–98. [4] Sharma, R. K., P. Ganesan, V. V. Tyagi, H. S. C. Metselaar, and S. C. Sandaran. “Developments in Organic Solid-Liquid Phase Change Materials and Their Applications in Thermal Energy Storage.” Energy Conversion and Management 95 (2015): 193–228. [5] Kuznik, Frédéric, and Joseph Virgone. “Experimental Assessment of a Phase Change Material for Wall Building Use.” Applied Energy 86(10) (2009): 2038–46. [6] Huseyin Benli, Aydin Durmus. “Performance Analysis of a Latent Heat Storage System with Phase Change Material for New Designed Solar Collectors in Greenhouse Heating.” Solar Energy 83 (2009): 2109–19. [7] Gracia, Alvaro De, Lidia Navarro, Albert Castell, and Luisa F. Cabeza. “Energy Performance of a Ventilated Double Skin Facade with PCM under Different Climates.” Energy & Buildings 91 (2015): 37–42. [8] Kosny, Jan, Kaushik Biswas, William Miller, and Scott Kriner. “Field Thermal Performance of Naturally Ventilated Solar Roof with PCM Heat Sink.” Solar Energy 86(9) (2012): 2504–14. [9] Bayés-García, L. et al. “Phase Change Materials (PCM) Microcapsules with Different Shell Compositions: Preparation, Characterization and Thermal Stability.” Solar Energy Materials and Solar Cells 94(7) (2010): 1235–40. [10] Yu, Shiyu, Xiaodong Wang, and Dezhen Wu. “Microencapsulation of N-Octadecane Phase Change Material with Calcium Carbonate Shell for Enhancement of Thermal Conductivity and Serving Durability: Synthesis, Microstructure, and Performance Evaluation.” Applied Energy 114 (2014): 632–43. [11] Giro-Paloma, J., Y. Konuklu, and A. I. Fernández. “Preparation and Exhaustive Characterization of Paraffin or Palmitic Acid Microcapsules as Novel Phase Change Material.” Solar Energy 112 (2015): 300–309. [12] Kim, Dowan et al. “Structure and Thermal Properties of Octadecane/expanded Graphite Composites as Shape-Stabilized Phase Change Materials.” International Journal of Heat and Mass Transfer 95 (2016): 735–41. [13] Kenisarin, Murat M., and Kamola M. Kenisarina. “Form-Stable Phase Change Materials for Thermal Energy Storage.” Renewable and Sustainable Energy Reviews 16(4) (2012): 1999–2040. [14] Zhang, Zhengguo et al. “Preparation and Thermal Energy Storage Properties of Paraffin / Expanded Graphite Composite Phase Change Material.” Applied Energy 91(1) (2012): 426–31. [15] Luo, Jian-Feng et al. “Numerical and Experimental Study on the Heat Transfer Properties of the Composite Paraffin/expanded Graphite Phase Change Material.” International Journal of Heat and Mass Transfer 84 (2015): 237–44. [15] Xu, Biwan, and Zongjin Li. “Paraffin/diatomite Composite Phase Change Material Incorporated Cement-Based Composite for Thermal Energy Storage.” Applied Energy 105 (2013): 229–37. [16] Li, Xiangyu, Jay G. Sanjayan, and John L. Wilson. “Fabrication and Stability of Form-Stable Diatomite/paraffin Phase Change Material Composites.” Energy and Buildings 76 (2014): 284–94.
12
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1129
[17] Karaipekli, Ali, and Ahmet Sarı. “Capric – Myristic Acid/ Expanded Perlite Composite as Form-Stable Phase Change Material for Latent Heat Thermal Energy Storage.” Renewable Energy 33 (2008): 2599–2605. [18] Ramakrishnan, Sayanthan, Jay Sanjayan, Xiaoming Wang, Morshed Alam, and John Wilson. “A Novel Paraffin/expanded Perlite Composite Phase Change Material for Prevention of PCM Leakage in Cementitious Composites.” Applied Energy 157 (2015): 85–94. [19] Zhang, Jianwu et al. “Preparation and Properties of Gypsum Based Energy Storage Materials with Capric Acid-Palmitic Acid/expanded Perlite Composite PCM.” Energy and Buildings 92 (2015): 155–60. [20] Wei, Ting, Baicun Zheng, Juan Liu, Yanfeng Gao, and Weihong Guo. “Structures and Thermal Properties of Fatty Acid/expanded Perlite Composites as Form-Stable Phase Change Materials.” Energy and Buildings 68(PARTA) (2014): 587–92. [21] Karaman, Sedat, Ali Karaipekli, Ahmet Sarı, and Alper Bic. “Polyethylene Glycol (PEG)/ Diatomite Composite as a Novel Form-Stable Phase Change Material for Thermal Energy Storage.” Solar Energy Materials & Solar Cells 95 (2011): 1647–53. [22] Mekaddem, N., S. Ben Ali, A. Hannachi, A. Mazioud, and M. Foi. “Latent Energy Storage Study in Simple and Honeycomb Structures Filled with a Phase Change Material.” IEEE Xplore - 7th International Renewable Energy Congress Proceedings. (2016) [23] Kandasamy, Ravi, Xiang-qi Wang, and Arun S. Mujumdar. “Transient Cooling of Electronics Using Phase Change Material (PCM)-Based Heat Sinks.” 28 (2008): 1047–57. [24] Liu, Lingkun, Di Su, Yaojie Tang, and Guiyin Fang. “Thermal Conductivity Enhancement of Phase Change Materials for Thermal Energy Storage: A Review.” Renewable and Sustainable Energy Reviews 62 (2016): 305–17. [25] Zhao, Y., C. Y. Zhao, Z. G. Xu, and H. J. Xu. “Modeling Metal Foam Enhanced Phase Change Heat Transfer in Thermal Energy Storage by Using Phase Field Method.” International Journal of Heat and Mass Transfer 99 (2016): 170–81. [26] Hossain, Rakib, Shohel Mahmud, Animesh Dutta, and Ioan Pop. “Energy Storage System Based on Nanoparticle-Enhanced Phase Change Material inside Porous Medium.” International Journal of Thermal Sciences 91 (2015): 49–58. [27] Zhang, Dong, Jianming Zhou, Keru Wu, and Zongjin Li. “Granular Phase Changing Composites for Thermal Energy Storage.” Solar Energy 78(3) (2005): 471–80. [28] Kheradmand, Mohammad et al. “Assessing the Feasibility of Impregnating Phase Change Materials in Lightweight Aggregate for Development of Thermal Energy Storage Systems.” Construction and Building Materials 89 (2015): 48–59. [29] Borreguero, A. M. et al. “Synthesis and Characterization of Microcapsules Containing Rubitherm RT27 Obtained by Spray Drying.” Chemical Engineering Journal 166(1) (2011): 384–90. [30] Borreguero, Ana M., Manuel Carmona, M. Luz Sanchez, José Luis Valverde, and Juan F. Rodriguez. “Improvement of the Thermal Behaviour of Gypsum Blocks by the Incorporation of Microcapsules Containing PCMS Obtained by Suspension Polymerization with an Optimal Core/coating Mass Ratio.” Applied Thermal Engineering 30(10) (2010): 1164–69. [31] Deveci, Senem Sirin, and Guldemet Basal. “Preparation of PCM Microcapsules by Complex Coacervation of Silk Fibroin and Chitosan.” Colloid and Polymer Science 287(12) (2009): 1455–67. [32] Fang, G., H. Li, X. Liu, and S. Wu. “Experimental Investigation of Performances of Microcapsule Phase Change Material for Thermal Energy Storage.” Chemical Engineering & Technology 33(2) (2010): 227–30 [33] Boudenne, Abderrahim, Laurent Ibos, Evelyne Gehin, and Yves Candau. “A Simultaneous Characterization of Thermal Conductivity and Diffusivity of Polymer Materials by a Periodic Method.” Journal of Physics D: Applied Physics 37(1) (2004): 132–39 [34] Boudenne, Abderrahim, Laurent Ibos, and Yves Candau. “Analysis of Uncertainties in Thermophysical Parameters of Materials Obtained from a Periodic Method.” Measurement Science and Technology 17(7) (2006): 1870–76. [35] Chung, Okyoung, Su Gwang Jeong, and Sumin Kim. “Preparation of Energy Efficient Paraffinic PCMs/expanded Vermiculite and Perlite Composites for Energy Saving in Buildings.” Solar Energy Materials and Solar Cells 137 (2015): 107–12. [36] Konuklu, Yeliz, Halime O. Paksoy, and Murat Unal. “Nanoencapsulation of N-Alkanes with Poly(styrene-Co-Ethylacrylate) Shells for Thermal Energy Storage.” Applied Energy 150 (2015): 335–40. [37] Sun, Dan, and Lijiu Wang. “Utilization of Paraffin/expanded Perlite Materials to Improve Mechanical and Thermal Properties of Cement Mortar.” Construction and Building Materials 101 (2015): 791–96 [38] Lu, Zeyu et al. “Preparation and Characterization of Expanded Perlite/paraffin Composite as Form-Stable Phase Change Material.” Solar Energy 108 (2014): 460–66. [39] Munteanu, S. B., C. Vasile, P. Poni, Alley Ro, and Ia¡ I. Romania. “Spectral and Thermal Characterization of Styrene- Butadiene Copolymers with Different Architectures.” Journal of Optoelectronics and Advanced Materials 7(6) (2005): 3135–48. [40] Karaipekli, Ali, and Ahmet Sari. “Development and Thermal Performance of Pumice/ Organic PCM/ Gypsum Composite Plasters for Thermal Energy Storage in Buildings.” Solar Energy Materials and Solar Cells 149 (2016): 19–28. [41] Anbalagan, G., S. Mukundakumari, K. Sakthi Murugesan, and S. Gunasekaran. “Infrared, Optical Absorption, and EPR Spectroscopic Studies on Natural Gypsum.” Vibrational Spectroscopy 50(2) (2009): 226–30. [42] Mandal, Pradip K., and Tanuj K. Mandal. “Anion Water in Gypsum (CaSO4.2H2O) and Hemihydrate (CaSO4.1/2H2O).” Cement and Concrete Research 32(2) (2002): 313–16. [43] Trigui, Abdelwaheb, Mustapha Karkri, and Igor Krupa. “Thermal Conductivity and Latent Heat Thermal Energy Storage Properties of LDPE/wax as a Shape-Stabilized Composite Phase Change Material.” Energy Conversion and Management 77 (2014): 586–96. [44] Khadiran, Tumirah, Mohd Zobir Hussein, Zulkarnain Zainal, and Rafeadah Rusli. “Activated Carbon Derived from Peat Soil as a Framework for the Preparation of Shape-Stabilized Phase Change Material.” Energy 82 (2015): 468–78
ScienceDirect Availableonline onlineatatwww.sciencedirect.com www.sciencedirect.com Available ScienceDirect Energy Procedia 00 (2018) 000–000 ScienceDirect Energy Procedia 00 (2018) 000–000 ScienceDirect Energy Procedia 157 Energy Procedia 00(2019) (2017)1118–1129 000–000
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Technologies and Materials for Renewable Energy, Environment and Sustainability, TMREES18, 19–21 September 2018, Athens, Greece Technologies and Materials for Renewable Energy, Environment and Sustainability, TMREES18, 19–21 September 2018, Athens, Greece 15th International Symposium onas District HeatingEnergy and Cooling Paraffin/The Expanded Perlite/Plaster Thermal Storage
Composite Paraffin/ Expanded Perlite/Plaster as Thermal Energy Storage Assessing the feasibility of using the heat demand-outdoor Composite a Najoua Mekaddem Samia Ben Alia, Magali Foisb,heat Ahmed Hannachiforecast temperature functiona*,for a long-term district demand Najoua Mekaddem *, Samia Ben Ali , Magali Fois , Ahmed Hannachi I. Andrić *, A. Pina , P. Ferrão , J. Fournier ., B. Lacarrière , O. Le Corre
a b Engineering, National Engineering a Laboratory of Engineering Processes and Industrial Systems, Departmenta of Chemical – Processes School a,b,c a a b c c of Gabes,University of Gabes, Street Omar Ibn El Khattab,Gabes 6029,Tunisia a bStudies and Research Center in Thermal, Environment and Systems, University Paris-Est, 61 Av.General de Gaulle 94010, Creteil Cedex, Laboratory of Engineering Processes and Industrial Systems, Department of Chemical – Processes Engineering, National Engineering School a IN+ Center for Innovation,of Technology and Policy Research - Instituto Superior Técnico, Av.6029,Tunisia Rovisco Pais 1, 1049-001 Lisbon, Portugal France Gabes,University of Gabes, Street Omar Ibn El Khattab,Gabes b b Recherche & Innovation, 291 Avenue Dreyfous Daniel,61 78520 Limay, France Studies and Research CenterVeolia in Thermal, Environment and Systems, University Paris-Est, Av.General de Gaulle 94010, Creteil Cedex, c Département Systèmes Énergétiques et Environnement - IMT Atlantique, 4 rue Alfred Kastler, 44300 Nantes, France France a
Abstract Abstract Abstract The use of thermal energy storage composite materials allows passive cooling and heating in buildings, yielding
substantial energy savings. The purpose of this study is to develop and test a new phase change material (PCM) District networks are storage commonly addressed in the literature as one the most effective solutions forleakage decreasing the The use heating of by thermal energy composite materials allows passive cooling and heating in buildings, yielding composite loading expanded perlite (EP) with paraffin (RT27) to ofform plaster composites. The tests greenhouse gas emissions from theRT27 building sector. These systems require high investments returned through the heat substantial savings. The purpose of thisrate. study isavoid to develop andleakage test a new phase change material (PCM) allowed to energy unfold the optimal loading To paraffin out which of theare composite structure, a sales. Due by to the changed climate conditions and building policies, heat demand in mixing the future decrease, ® perlite composite loading expanded (EP)used with to form plaster composites. The leakage tests (SL), was toparaffin coat renovation the(RT27) RT27/EP composite before it could with plaster. waterproof product, Sikalatex prolonging the investment return period. allowed to unfold the optimal RT27 loadinginrate. To were avoidassessed. paraffinThe leakage of the composite structure,ona Thermal properties of RT27/EP/SL integrated plaster effectout of aluminum powder insertion The main scope of this paper is to® assess the feasibility of using the heat demandcomposite – outdoor temperature function heatplaster. demand (SL),properties, was used was to coat the RT27/EP before it for with waterproof product, Sikalatex enhancing the composite thermal investigated. Paraffin loading ratemixing was 60% by direct forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of on 665 Thermal properties RT27/EP/SL in plaster composites were assessed. The effect aluminum powder insertion impregnation. FTIRofanalyses provedintegrated that the produced showed a goodofchemical compatibility between buildings that vary in both construction period and typology. Three weather scenarios (low, medium, high) and three district enhancing the composite properties, investigated. Paraffin energy loadingstorage rate was 60% ofby51.57 direct different components. DSC thermal analyses(shallow, revealed thatwas composites have suitable capacities ± renovation scenarios were developed intermediate, deep). To estimate the error, obtained heat demand values were -1 proved that the produced composites showed a good chemical compatibility between impregnation. FTIR analyses for RT27/EP/SL and RT/EP/SL/Al, respectively. 0.01 and 49.95 ±0.15 kJ.kg compared with results from a dynamic heat demand model, previously developed and validated by the authors. different components. DSC analyses revealed that composites haveThermal suitablecycling energy tests storage capacities of 51.57 ± These composites suitable for indoor temperature regulation. showed a good thermal The results showed are that when -1 only weather change is considered, the margin of error could be acceptable for some applications for RT27/EP/SL and RT/EP/SL/Al, respectively. 0.01 and 49.95 ±0.15 kJ.kg stability of plaster PCM composite. Thermal conductivity of plaster composite containing 50% wt of (the error in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation These composites are temperature Thermal cycling tests showed a goodconsidered). thermal RT27/EP/SL/Al composite wasfor increased by(depending 80% andregulation. 68% at 12°C andrenovation 40°C respectively compared with the scenarios, the error valuesuitable increased upindoor to 59.5% on the weather and scenarios combination stability of plaster PCM composite. Thermal conductivity of plaster composite containing 50% wt aluminum free composite. The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to of the RT27/EP/SL/Al composite was hours increased by 80% andthe 68% at 12°C 40°C respectively compared with the decrease in the number of heating of 22-139h during heating seasonand (depending on the combination of weather and © 2018 2019 The Thefree Authors. Published by Ltd. aluminum composite. © Authors. Published by Elsevier Elsevier Ltd. hand, function intercept increased for 7.8-12.7% per decade (depending on the renovation scenarios considered). On the other This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) coupled and scenarios). The values suggested could be scientific used to modify the of function parameters for the scenarios considered, and Selection peer-review under responsibility of the committee Technologies and Materials for Renewable Energy, © 2018 The Published by Elsevier Ltd. improve theAuthors. accuracy of heat demand estimations. Environment and Sustainability, TMREES18. © 2017 The Authors. Published by Elsevier Ltd. * Corresponding author. Tel.: +21650519474; fax: +0-000-000-0000 . Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and E-mail address: [email protected] Cooling. [email protected]
* Corresponding author. Tel.: +21650519474; fax: +0-000-000-0000 . E-mail address: [email protected] Keywords: Heat demand; Forecast; Climate change [email protected] 1876-6102 © 2018 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection peer-review under responsibility of the scientific 1876-6102and © 2018 The Authors. Published by Elsevier Ltd. committee of Technologies and Materials for Renewable Energy, Environment and TMREES18. ThisSustainability, is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and©peer-review under responsibility the scientific 1876-6102 2017 The Authors. Published byofElsevier Ltd. committee of Technologies and Materials for Renewable Energy, Environment 1876-6102 © 2019TMREES18. The Authors. Published by Elsevier Ltd. and Sustainability, Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and Cooling. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsibility of the scientific committee of Technologies and Materials for Renewable Energy, Environment and Sustainability, TMREES18. 10.1016/j.egypro.2018.11.279
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Najoua Mekaddem et al./ Energy Procedia 00 (2018) 000–000
This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsibility of the scientific committee of Technologies and Materials for Renewable Energy, Najoua Mekaddem et al. / Energy Procedia 157 (2019) 1118–1129 1119 Environment and Sustainability, TMREES18. Keywords: Composite; Latent heat energy storage; Phase Change Material; Porous material
1. Introduction Energy Storage Systems (ESS) have recently great attractive features to improve energy efficiency. Thermal Energy Storage (TES) involving latent heat and sensible heat storage or both of them becomes an alternative and a cheaper technique to reduce energy consumption and enhance the comfort level in buildings [1, 2]. Phase Change Materials (PCMs) are widely used as thermal energy storage materials for temperature control applications [3]. PCMs can be included in building structures in different ways, wallboards, ceilings and floors or incorporated into construction materials. The solar energy excess available in the off-peak time of sunshine hours can be stored in TES devices based on PCMs for later use in the night hours [4]. For this purpose, Kuznik and Virgone [5] evaluated the thermal performances of a PCM copolymer composite wallboard in a test room for a summer day, a winter day and a mid season day. As results, they found that the overheating effect was reduced, the energy stored at high temperature was liberated to air room when the temperature minimum was reached. Also, the human thermal comfort is improved by radiative heat transfer and the natural convection is ameliorated by PCM, preventing thermal stratifications. Huseyin et al. [6] studied the performance of PCM storage unit during the charge and discharge periods for greenhouse heating. In comparison with the conventional heating, the solar air collector integrated with PCM created a 6-9 °C temperature variation between the inside and outside of the greenhouse, providing about 1823% of total daily thermal energy requirements of the greenhouse for 3-4 h. Gracia et al. [7] inspected the potential of PCM panels containing paraffin SP22, installed in ventilated facade to provide energy benefits during heating period under mediterranean-continental climate conditions. For the cold storage sequence, the cooling supply provided is limited to values below 12 MJ/day while free cooling can reach values above 150 MJ/day depending on the region. Yet, the cold storage sequence provided cooling during 3 or 4 h at cooling demand period. Kosny et al. [8] tested experimentally the thermal performance of two roof configurations; a control asphalt shingle roof and a PV-PCM roof/attic one. Results showed about 30% heating and 50% cooling load reductions for the PV-PCM roof/attic configuration compared to control asphalt shingle roof. Meanwhile, Researchers aim to find novel efficient and economical energy storage materials. They have investigated stabilized PCM composites and studied heat transfer enhancement techniques shape in order to have a great storage capacity. Foremost, it is essential to select suitable materials for preparing an appropriate PCM composite good thermal properties. This composite should maintain its solid shape even when PCM changes from solid to liquid state. The main methods to obtain stabilized shape or stable form of PCM composites are encapsulation by using shell materials [9, 10], polymerization techniques [11] and impregnation into organic or inorganic supports. Shell materials encapsulation and polymerization methods have high cost and complex manufacturing processes but incorporation method in porous matrices is simple and has a low processing cost [12]. Using porous structure materials as supports to obtain the stable PCM composite form is developing as perspective framework of heat storage materials [13]. Due to their abundance, low cost, high fire resistance and high porosity, porous material are appropriate supports to contain PCMs. Incorporating heat storage material into porous texture such as expanded graphite [14, 15], activated carbon [3], diatomite [16, 17] and expanded perlite [18, 19, 20] can be done by two ways, direct immersion or vacuum impregnation. Wei et al. prepared a stable PCM composite form containing fatty acids (Capric acid and capric-stearic acid) incorporated in an expanded perlite using the direct fusion adsorption method [21]. The PCM insertion rate was 50%wt. Latent heat values of CA/EP composites are 87.3 J.g-1 for the melting and 89.0 J.g-1 for the freezing processes. An appropriate binary paraffin blends/opal composite was developed by Sun et al. to be used as an indoor thermal energy storage [2]. Its phase transition temperature and latent heat were respectively 24.9 °C and 59 J.g-1. Khadiran et al [3] studied the preparation and thermal properties of n-octadecane activated carbon composite which showed a good thermal reliability even after several melting/freezing cycles. The amount of the loaded n-octadecane was 42.5 %wt. Karaman et al. [22] prepared
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a polyethylene glycol (PEG)/diatomite composite by vacuum impregnation. PEG was retained by 50 % wt into pores of diatomite without leakage. Zhang et al [20] produced a Capric Acid- Palmitic Acid/Expanded Perlite composite PCM using vacuum impregnation method. The composite was mixed with gypsum to obtain thermal-regulating gypsum board. The phase change temperature range of PCM composite was from 24 to 31°C, and its latent heat was 88.4 J.g-1. Several techniques have been used to enhance heat transfer rates of PCM composites such as embedding PCMs in highly conductive porous media like graphite or metal matrices [23], dispersing highly conductive particles within PCMs, multiple PCMs and microencapsulation of PCM [24, 25]. In some cases, depending on the insertion of the shape stabilized composite in buildings, it seems necessary to protect the composite against destruction which can be caused by interaction with surrounding materials, additional thermal stresses and vapor pressures caused by the volume change during phase transition [17]. Adding coating material to the PCM composite was adopted in few studies. As studied by Zhang et al. [27], after the impregnation process, to prevent leakage, the porous material loaded with PCM was treated by a slurry of latex and polymer modified cement for 5 min. During the impregnation/ encasement of PCMs in lightweight aggregates (LWAs), Kheradmand et al [28] tested four different coating solutions (Sikalastic-490T, Weber Dry, Lastic Makote3 and ECM-2) in order to obtain an adequate coating. Their results showed that the amount of leaked PCM from different composites under cooling/ heating cycles were only exceeding 0.5%. As described in literature, the encapsulation of paraffin wax RT27 was performed by coacervation and spraydrying [29], polymerization, emulsion polymerization [30] which are complex, expensive and difficult to be controlled [30, 31, 32]. Therefore, it is intended to develop a composite using simple technique and construction materials. Expanded perlite (EP) is widely used as an insulating material in construction. Despite its highly porous interne structure, low density, low cost and good thermal reliability [21], few studies have investigated it to elaborate thermal energy storage composites. The aim of this work is to obtain a new composite with a melting temperature between 20°C and 30°C appropriate to be included in building structures. The RT27 and expanded perlite are chosen to prepare a stable form heat energy storage plaster composite with good thermal properties. Using direct impregnation, the composite was prepared by loading paraffin RT27 into EP with a commercial coating material and inserted into plaster. To improve its thermal conductivity, an aluminum powder was added to the composite after drying the coating material. The effect of adding a coating material and a metal powder on the thermal performances of RT27/EP were analyzed. 2. Materials and methods 2.1. Materials Paraffin wax namely RT27 was chosen as thermal storage material. It has a melting temperature range of 25-28 °C which is close the ambient temperature human comfort. RT27 was kindly supplied by Rubitherm technologies GmbH. Paraffin is a mixture of solid saturated hydrocarbons with the molecular formula CnH2n+2(4% C17H32; 45% C18H34; 36% C19H36; 12% C20H38; 2% C21H40 and 1% other alkanes) [9]. Table 1 gives the relevant RT27 properties as reported by Rubitherm technologies GmbH. Table 1. Properties of RT27 as reported by Rubitherm GmbH Melting Area
25-28 °C
Specific heat capacity
2 kJ.kg-1.K-1
Heat storage capacity ±7.5% [20 °C 35 °C]
179 kJ.kg-1
Thermal conductivity
0.2 W.m-1.K-1
Density liquid at 40 °C
760 kg.m-3
Density solid at 15 °C
880 kg.m-3
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Expanded perlite (EP) was acquired from PERLA group Tunisia. The main chemical constituents of EP were determined using X-ray fluorescence spectrometer (XRF, JSX-3201Z) and are given in table 2. Sikalatex® (SL) is a resin water proof adherent that was purchased from Sika Group and used as coating material. Aluminum powder (Al) was supplied from Minerals-water Ltd and the plaster was obtained from Knauf-Meknassy-Tunisia. Table 2. Chemical composition of expanded perlite. Constituent
SiO2
Al2O3
Fe2O3
CaO
Na2O
K2O
MgO
Ratio%
74.3
12.6
2.7
1.0
3.4
6.0
0.1
2.2. Preparation of the paraffin/expanded perlite /Plaster composite The expended perlite was dried at 110 °C for 24h in order to eliminate moisture. The RT27 was heated to 40 °C. The dried expanded perlite (EP) was added at different rates to the melted paraffin. The mixture was stirred until the PCM was uniformly dispersed into the EP pores. The highest ratio of paraffin insertion in EP was determined by two leakage tests. The first test was realized after the impregnation process and carried for four hours. The second test was performed by maintaining the loaded EP at 40 °C for three days. In each case, the relative weight loss of the loaded EP is determined. Because of the hydrophilic character of the EP, when preparing plaster composite structures, paraffin may be displaced by water. To prevent paraffin leakage, the RT27 /EP composite was coated by polymer water proof Sikalatex®. The impact of adding an aluminum powder was investigated in 10%wt to enhance the thermal conductivity. Plaster boards were prepared by mixing the obtained PCM composite with gypsum and water. The gypsum powder and water were mixed and then the PCM composite was added at different mass fractions. For each fraction, the mixture was uniformly stirred until forming a homogeneous slurry which was poured into a 40mm*40mm*6mm mould. The mould was dried at room temperature. 2.3. Characterization techniques Fourier-transform infrared spectroscopy (FT-IR) was carried out by a Frontier, Perkin Elmer spectrometer between 500 and 4000 cm-1. The melting temperature, latent heat and heat capacity were measured by a Differential Scanning Calorimeter (Diamond DSC of Perkin Elmer) at 10 °C.min-1 between -30 °C and 60 °C. The thermal conductivity and thermal diffusivity were estimated simultaneously by the periodic method used at CERTES [33, 34]. The measurement principle of this method is to use a small temperature modulation in a parallelepiped-shape sample placed between two metal plates. The bottom plate temperature was controlled thanks to a Peltier module. The thermal stress imposed by this plate was a sum of five sinusoids for which amplitude and frequency were controlled. Heat transfer through the sample leads to a temperature variation in the upper plate. The thermal conductivity and diffusivity parameters were then calculated by inverse method from records of input and output temperatures' variations. 3. Results and discussion After producing the PCM composite material several tests and characterization techniques were conducted on the samples as described in previous section. 3.1. Leakage tests The leakage tests were carried out to study the ability of the EP pores to retain the PCM even when the composite was kept at temperature above the melting point. Different PCM loading rates ranging from 33% to 90%, were prepared and conditioned at 40 °C for four hours. A paraffin amount adhering the container walls was observed
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when the loading percent was high. These samples were also kept for three days in an oven at 40 °C. Significant paraffin amount can leak out of the composite material for paraffin loading percent higher than 60%. The first leakage test showed that for 33% and 50% there was no leakage observed, the paraffin was totally contained within the EP pores. But, trace amounts can be significant for paraffin loading percenteses higher than 60%. The second test revealed that for paraffin loading rate below 60% the leaked amount was insignificant. However, a considerable amount of seepage was found for the samples of 75% and 90%. Thus, that optimal RT27 loading rate is around 60% for which the paraffin would be confined to EP pores. The RT27 was successfully incorporated into the EP porous structure and the seepage could be avoided. These results give information regarding the loading capacity. The PCM loading percent of 60% was chosen as an optimum to prepare the PCM composite. 3.2. FTIR analyses of PCM composite FTIR analysis was carried out to identify possible chemical or physical interactions between different components of the composite. Fig. 1 shows FTIR transmission spectrum of characteristic peaks of RT27, EP, SL, plaster and their composites.
Fig. 1. FTIR spectrum of components and prepared composites
As reported in literature, paraffin wax has three characteristic transmission or absorption bands: rocking vibration of -CH2 at 721 cm-1, deformation vibration of -CH2 and -CH3 at 1466 cm-1, and three intensive peaks at 2852 cm-1, 2921 cm-1 and 2957 cm-1 which belong to alkyl stretching vibrations of -CH2 and -CH3, [12, 35, 36]. Expanded perlite spectrum presents a peak at 788 cm-1 that could be attributed to the stretching vibration of OH and a large one around 1021 cm-1 most probably corresponding to Si-O-Si asymmetric stretching vibration [37]. The bands for RT27/EP spectrum (Fig.1.a) are present without any shifting. FTIR spectrum confirmed that these bondings were not broken or changed during the RT27 incorporation process as reported by Chung et al. [35]. Thus, paraffin loading in the EP pores occurs without chemical reactions and is only driven by capillary and surface tension forces [38]. Similar result has been previously determined by other studies [38, 37]. As shown in Fig.1.b, the SL has a more complex structure, the peaks at 698 cm-1 and 758 cm-1 were attributed respectively to an out of plane bending and deformation vibrations of the CH groups in the aromatic rings [39]. Peak at 966 cm-1 could reflect an out of plan vibrations of CH groups near the double bond. Peaks at 1452 cm-1 and 1493 cm-1 may correspond to the stretching vibrations of the carbons in aromatic rings [39]. There is a strong peak at 2919 cm-1 which could be relevant to asymmetrical stretching vibrations of the CH2 groups and a broad one between 3115 and 3723 cm-1 probably corresponding to OH vibration [39, 40]. As reported by Munteanu et al. [39], the SL spectrum is consistent with copolymers used in sealants, coatings, waterproofing materials. In the RT27/EP/SL spectrum (Fig.1.b), no additional peaks were noticed. However, the large band between 3115 and 3723 cm-1 became less intensive. For the plaster spectrum (Fig.1.c), Sulfate ion bending modes vibrations occur at 596 cm-1 and 667 cm-1 and asymmetric stretching
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at 1104 cm-1 [41]. The peaks at 1622 cm-1 and 1685 cm-1 could be related to water bending vibrations. Mandal et al. [42] suggested to assign the two bands at 3404 cm-1 and 3528 cm-1 to OH stretching. As can be seen by adding the SL to the RT27/EP and inserting the obtained composite into plaster, did not lead to the appearance of new peaks in the FTIR spectrum of RT27/EP/SL/plaster. Thus, RT27/EP composite possess a good chemical compatibility with SL coating and plaster. 3.3. DSC analyses of PCM composite The DSC instrument used for thermal characterization was calibrated on enthalpy mode. The measurements were repeated to show reproducibility and avoid the effect of thermal history for each sample. Samples were set in aluminium solid pans and analyses were carried out at 10 °C.min-1 between -30 °C and 60 °C. Fig. 2 and Fig. 3 show DSC curves of pure paraffin RT27 and composites, respectively. As shown in Fig. 2, paraffin has two peaks. The major one corresponds to solid-liquid phase change. The minor peak corresponds to the solid-solid transition. From heating and cooling DSC analyses, melting and crystallization onset temperatures are very close at around 25 °C. The RT27 has a relatively high phase change melting/crystallization enthalpy of 154 ±2.3 kJ.kg-1. The measured specific heat capacities are 1.7 ±0.07 kJ.kg-1.°C-1 and 2.18 ±0.06 kJ.kg-1.°C-1 at solid and liquid states, respectively. The average heat storage capacity between 20 and 35 °C is 186.7 kJ.kg-1 which is close to the value provided by the manufacturer data sheet (table 1). The slight differences could be attributed to inherent experimental errors. In fact, in the literature much higher discrepancies were reported. This is due to the sensitivity of DSC measurements for which the results are affected by many factors such as structure and mass of sample, heating and cooling rate and the selected type and extremities of baseline, as mentioned by Trigui et al. [43]. The data extracted from DSC curves of RT27 and RT27/EP, RT27/EP/SL, RT27/EP/SL/Al composites are summarized in table 3 for heating and cooling processes. As expected, the specific heat storage capacity decreases with the decreasing RT27 content of PCM composite. The phase change melting and crystallization temperatures of composites (RT27/ EP, RT27/ EP/ SL and RT27/ EP/ SL/ Al) are slightly changed due to impregnation. This can be explained by some interactions or movements of paraffin molecules into interne porous structure of EP as previously reported by Karaipekli et al. [40]. Moreover, it is noticed that, when Al is added there is no significant effect on the melting and freezing onset temperatures (table 3). However, during the cooling process a clear new peak appeared at the tail of RT27 phase change when Al was incorporated. Latent heat storage capacities of produced composites were compared to those reported in the literature as shown in table 4. It is clear that RT27/EP/SL is well suited for air conditioning applications. Table 3. Latent heat energy storage properties of RT27 and prepared composites. Solid- liquid transition
Solid-solid transition
Samples
Tm (°C)
Tf (°C)
Average ΔHm (kJ.kg -1)
Tm (°C)
Tf (°C)
Average ΔHm (kJ.kg -1)
RT27
25.1
25
154.00 ±2.30
1.5
1.0
21.78 ±0.71
RT27/EP
26.3
25.5
84.00 ±0.50
2.6
0.9
10.61 ±0.61
RT27/EP/SL
26.3
25.8
51.57 ±0.01
2.3
1.4
6.43 ±0.32
RT27/EP/SL/Al
26.1
25.3
49.95 ±0.15
2.2
0.9
6.18 ±0.22
m: melting, f: freezing, t: transition
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Fig. 2. DSC heating and cooling curves of RT27 paraffin at 10°C.min-1
Fig. 3. DSC heating and cooling curves of RT27 paraffin and different composites at 10°C.min-1
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Table 4. Latent energy storage capacities of some PCM composites. PCM composites
Tm (°C)
Tf (°C)
ΔHm (kJ.kg-1)
Reference
PEG (50 wt%)/ diatomite
27.7
32.2
87.1
[22]
Capric-mystiric acid (55 wt%)/expanded perlite
21.7
20.7
85.4
[18]
N-octadecane (41.4 wt%)/activated carbon
28.0
27.6
95.4
[45]
RT21/ uncoated expanded perlite
17.2
24.3
35.5
[19]
RT21/ coated expanded perlite
16.3
24.6
60.9
[19]
RT27/EP
26.3
25.5
84.0
Present study
RT27/EP/SL
26.3
25.8
51.6
Present study
m: melting, f: freezing
Evaluating thermal characteristics of composite PCM integrated in a material construction like plaster is required. As shown in DSC results given in Fig. 4, the latent heat storage of RT27/EP/SL/plaster increases with the increasing RT27 content of the composite. The processing of the heat flow curve allowed to obtain the phase change latent heat for each prepared composite material. For 50% RT27/EP/Sl content, the latent heat was about 22.5 ±0.4 kJ.kg-1. To investigate the thermal reliability of RT27/EP/SL/plaster and RT27/EP/SL/Al/plaster as heating storage material, thermal cycling tests were performed and the corresponding DSC curves for 50% composite content in plaster before and after cycling are shown in Fig. 5. As can be observed, the two composites have a good thermal reliability, their curves are almost perfectly overlapping for the sample free of Al.
Fig. 4. DSC heating and cooling curves of PCM plaster composites at 10°C.min-1
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Fig. 5. DSC heating and cooling curves of PCM plaster composites with (a) and without (b) aluminum after 30 cycles (plaster content: 50%).
3.4. Thermal conductivity improvement The low PCM thermal conductivity could lead to heat transfer low rates, limiting the heat storage and retrieval capacity during the heating and cooling processes. Thus, increasing energy consumption to maintain the desired temperature [35]. Because our MCP composite has low heat conducting components, an aluminum powder was added after drying the RT27/EP/SL composite at 10 wt%. Thermal conductivity and diffusivity measurements were then carried out at 12 °C, at which no phase change is observed and at 40 °C when the RT27 would be at liquid state. The results are given in table 5. The thermal properties of each composite components were also added in the same table. At 12 °C and 40 °C, adding Al to the composite allowed to increase the thermal conductivity by 66% and 69%, respectively. The improvement in thermal conductivity was consistent and very important regardless of RT27 state. Compared to PCM composite without Al, the observed thermal diffusivity increase was about 200% and 67% for 12 °C and 40 °C, respectively. The measured thermal conductivity values of RT27/EP/SL inserted in plaster with and without aluminum for different plaster mass fractions are shown in Fig. 6. Compared to plaster, for composites free of Al, as RT27/EP/SL content increases, the thermal conductivity slightly decreases then reaches a maximum at 40% wt. This behavior was observed regardless of The RT27 state. In the literature similar conflicting results of thermal conductivity were reported [20]. The PCM incorporation in plaster could improve or deteriorate thermal conductivities of composites. However, when Al was added thermal conductivity increases with the decreasing plaster content. With the reduction in plaster content and the increase of aluminum composite content, the thermal conductivity of composites increased, especially when the RT27/EP/SL/Al fraction was higher than 20%. For high plaster contents exceeding 80%, adding Al does not improve very much composite thermal conductivity. The highest thermal conductivity improvement was obtained for plaster content of 50%. As shown in this Fig. 6, PCM plaster composite thermal conductivity was enhanced by 80% and 68% at 12 °C and 40 °C, respectively. Thermal diffusivity variation with plaster contents is presented in Fig. 7. As can be seen, the same evolution has been observed for 12 °C and 40 °C. The thermal diffusivity was enhanced by more than 30% when Al was added.
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12 (°C)
40 (°C)
λ (W.m-1.K-1)
α (mm2.s-1)
λ (W.m-1.K-1)
α (mm2.s-1)
RT27
0.166 ±0.005
0.073 ±0.005
-
-
SL
0.167 ±0.003
0.102 ±0.003
0.187 ±0.009
0.093 ±0.007
RT27/EP/SL
0.149 ±0.015
0.112 ±0.008
0.176 ±0.014
0.153 ±0.015
RT27/EP/SL/Al
0.247 ±0.006
0.226 ±0.008
0.297 ±0.009
0.256 ±0.011
Fig. 6. PCM composite material thermal conductivities for different plaster contents at 12°C (a) and 40°C (b).
Fig. 7. PCM composite material thermal diffusivities for different plaster contents at 12°C (a) and 40 °C (b)
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4. Conclusion A stabilized shape composite was successfully prepared by paraffin RT27 impregnating into Expanded Perlite (EP). The maximum RT27 loading rate was 60 wt%. To prevent leakage, the RT27/EP was coated by water proof product, SikaLatex® (SL). The RT27/EP/SL composite was mixed with gypsum to obtain thermal regulating plaster composite. The plaster PCM composites were characterized by FTIR, DSC and periodic method for thermal properties's measurements. FTIR analyses confirmed the good chemical compatibility between all composite components. DSC analysis showed good thermal reliability and stability. No shifting of phase change and transition temperatures was observed. Thermal conductivities were improved by adding aluminum powder. In plaster composite, the thermal conductivity reached 0.47 W.m-1.K-1 for 50% wt RT27/EP/SL/Al content. The PCM plaster composite is suitable for regulating indoor temperature in buildings. Acknowledgements This project is carried out within the framework of a MOBIDOC doctoral thesis of the PASRI program financed by the EU and managed by the ANPR. References [1] Rathod, Manish K., and Jyotirmay Banerjee. “Thermal Stability of Phase Change Materials Used in Latent Heat Energy Storage Systems: A Review.” Renewable and Sustainable Energy Reviews 18 (2013): 246–58. [2] Sun, Zhiming, Weian Kong, Shuilin Zheng, and Ray L. Frost. “Study on Preparation and Thermal Energy Storage Properties of Binary Paraffin Blends/opal Shape-Stabilized Phase Change Materials.” Solar Energy Materials and Solar Cells 117 (2013): 400–407. [3] Khadiran, Tumirah, Mohd Zobir Hussein, Zulkarnain Zainal, and Rafeadah Rusli. “Encapsulation Techniques for Organic Phase Change Materials as Thermal Energy Storage Medium: A Review.” Solar Energy Materials and Solar Cells 143 (2015): 78–98. [4] Sharma, R. K., P. Ganesan, V. V. Tyagi, H. S. C. Metselaar, and S. C. Sandaran. “Developments in Organic Solid-Liquid Phase Change Materials and Their Applications in Thermal Energy Storage.” Energy Conversion and Management 95 (2015): 193–228. [5] Kuznik, Frédéric, and Joseph Virgone. “Experimental Assessment of a Phase Change Material for Wall Building Use.” Applied Energy 86(10) (2009): 2038–46. [6] Huseyin Benli, Aydin Durmus. “Performance Analysis of a Latent Heat Storage System with Phase Change Material for New Designed Solar Collectors in Greenhouse Heating.” Solar Energy 83 (2009): 2109–19. [7] Gracia, Alvaro De, Lidia Navarro, Albert Castell, and Luisa F. Cabeza. “Energy Performance of a Ventilated Double Skin Facade with PCM under Different Climates.” Energy & Buildings 91 (2015): 37–42. [8] Kosny, Jan, Kaushik Biswas, William Miller, and Scott Kriner. “Field Thermal Performance of Naturally Ventilated Solar Roof with PCM Heat Sink.” Solar Energy 86(9) (2012): 2504–14. [9] Bayés-García, L. et al. “Phase Change Materials (PCM) Microcapsules with Different Shell Compositions: Preparation, Characterization and Thermal Stability.” Solar Energy Materials and Solar Cells 94(7) (2010): 1235–40. [10] Yu, Shiyu, Xiaodong Wang, and Dezhen Wu. “Microencapsulation of N-Octadecane Phase Change Material with Calcium Carbonate Shell for Enhancement of Thermal Conductivity and Serving Durability: Synthesis, Microstructure, and Performance Evaluation.” Applied Energy 114 (2014): 632–43. [11] Giro-Paloma, J., Y. Konuklu, and A. I. Fernández. “Preparation and Exhaustive Characterization of Paraffin or Palmitic Acid Microcapsules as Novel Phase Change Material.” Solar Energy 112 (2015): 300–309. [12] Kim, Dowan et al. “Structure and Thermal Properties of Octadecane/expanded Graphite Composites as Shape-Stabilized Phase Change Materials.” International Journal of Heat and Mass Transfer 95 (2016): 735–41. [13] Kenisarin, Murat M., and Kamola M. Kenisarina. “Form-Stable Phase Change Materials for Thermal Energy Storage.” Renewable and Sustainable Energy Reviews 16(4) (2012): 1999–2040. [14] Zhang, Zhengguo et al. “Preparation and Thermal Energy Storage Properties of Paraffin / Expanded Graphite Composite Phase Change Material.” Applied Energy 91(1) (2012): 426–31. [15] Luo, Jian-Feng et al. “Numerical and Experimental Study on the Heat Transfer Properties of the Composite Paraffin/expanded Graphite Phase Change Material.” International Journal of Heat and Mass Transfer 84 (2015): 237–44. [15] Xu, Biwan, and Zongjin Li. “Paraffin/diatomite Composite Phase Change Material Incorporated Cement-Based Composite for Thermal Energy Storage.” Applied Energy 105 (2013): 229–37. [16] Li, Xiangyu, Jay G. Sanjayan, and John L. Wilson. “Fabrication and Stability of Form-Stable Diatomite/paraffin Phase Change Material Composites.” Energy and Buildings 76 (2014): 284–94.
12
Najoua Mekaddem et al. / Energy Procedia 157 (2019) 1118–1129 Najoua Mekaddem et al./ Energy Procedia 00 (2018) 000–000
1129
[17] Karaipekli, Ali, and Ahmet Sarı. “Capric – Myristic Acid/ Expanded Perlite Composite as Form-Stable Phase Change Material for Latent Heat Thermal Energy Storage.” Renewable Energy 33 (2008): 2599–2605. [18] Ramakrishnan, Sayanthan, Jay Sanjayan, Xiaoming Wang, Morshed Alam, and John Wilson. “A Novel Paraffin/expanded Perlite Composite Phase Change Material for Prevention of PCM Leakage in Cementitious Composites.” Applied Energy 157 (2015): 85–94. [19] Zhang, Jianwu et al. “Preparation and Properties of Gypsum Based Energy Storage Materials with Capric Acid-Palmitic Acid/expanded Perlite Composite PCM.” Energy and Buildings 92 (2015): 155–60. [20] Wei, Ting, Baicun Zheng, Juan Liu, Yanfeng Gao, and Weihong Guo. “Structures and Thermal Properties of Fatty Acid/expanded Perlite Composites as Form-Stable Phase Change Materials.” Energy and Buildings 68(PARTA) (2014): 587–92. [21] Karaman, Sedat, Ali Karaipekli, Ahmet Sarı, and Alper Bic. “Polyethylene Glycol (PEG)/ Diatomite Composite as a Novel Form-Stable Phase Change Material for Thermal Energy Storage.” Solar Energy Materials & Solar Cells 95 (2011): 1647–53. [22] Mekaddem, N., S. Ben Ali, A. Hannachi, A. Mazioud, and M. Foi. “Latent Energy Storage Study in Simple and Honeycomb Structures Filled with a Phase Change Material.” IEEE Xplore - 7th International Renewable Energy Congress Proceedings. (2016) [23] Kandasamy, Ravi, Xiang-qi Wang, and Arun S. Mujumdar. “Transient Cooling of Electronics Using Phase Change Material (PCM)-Based Heat Sinks.” 28 (2008): 1047–57. [24] Liu, Lingkun, Di Su, Yaojie Tang, and Guiyin Fang. “Thermal Conductivity Enhancement of Phase Change Materials for Thermal Energy Storage: A Review.” Renewable and Sustainable Energy Reviews 62 (2016): 305–17. [25] Zhao, Y., C. Y. Zhao, Z. G. Xu, and H. J. Xu. “Modeling Metal Foam Enhanced Phase Change Heat Transfer in Thermal Energy Storage by Using Phase Field Method.” International Journal of Heat and Mass Transfer 99 (2016): 170–81. [26] Hossain, Rakib, Shohel Mahmud, Animesh Dutta, and Ioan Pop. “Energy Storage System Based on Nanoparticle-Enhanced Phase Change Material inside Porous Medium.” International Journal of Thermal Sciences 91 (2015): 49–58. [27] Zhang, Dong, Jianming Zhou, Keru Wu, and Zongjin Li. “Granular Phase Changing Composites for Thermal Energy Storage.” Solar Energy 78(3) (2005): 471–80. [28] Kheradmand, Mohammad et al. “Assessing the Feasibility of Impregnating Phase Change Materials in Lightweight Aggregate for Development of Thermal Energy Storage Systems.” Construction and Building Materials 89 (2015): 48–59. [29] Borreguero, A. M. et al. “Synthesis and Characterization of Microcapsules Containing Rubitherm RT27 Obtained by Spray Drying.” Chemical Engineering Journal 166(1) (2011): 384–90. [30] Borreguero, Ana M., Manuel Carmona, M. Luz Sanchez, José Luis Valverde, and Juan F. Rodriguez. “Improvement of the Thermal Behaviour of Gypsum Blocks by the Incorporation of Microcapsules Containing PCMS Obtained by Suspension Polymerization with an Optimal Core/coating Mass Ratio.” Applied Thermal Engineering 30(10) (2010): 1164–69. [31] Deveci, Senem Sirin, and Guldemet Basal. “Preparation of PCM Microcapsules by Complex Coacervation of Silk Fibroin and Chitosan.” Colloid and Polymer Science 287(12) (2009): 1455–67. [32] Fang, G., H. Li, X. Liu, and S. Wu. “Experimental Investigation of Performances of Microcapsule Phase Change Material for Thermal Energy Storage.” Chemical Engineering & Technology 33(2) (2010): 227–30 [33] Boudenne, Abderrahim, Laurent Ibos, Evelyne Gehin, and Yves Candau. “A Simultaneous Characterization of Thermal Conductivity and Diffusivity of Polymer Materials by a Periodic Method.” Journal of Physics D: Applied Physics 37(1) (2004): 132–39 [34] Boudenne, Abderrahim, Laurent Ibos, and Yves Candau. “Analysis of Uncertainties in Thermophysical Parameters of Materials Obtained from a Periodic Method.” Measurement Science and Technology 17(7) (2006): 1870–76. [35] Chung, Okyoung, Su Gwang Jeong, and Sumin Kim. “Preparation of Energy Efficient Paraffinic PCMs/expanded Vermiculite and Perlite Composites for Energy Saving in Buildings.” Solar Energy Materials and Solar Cells 137 (2015): 107–12. [36] Konuklu, Yeliz, Halime O. Paksoy, and Murat Unal. “Nanoencapsulation of N-Alkanes with Poly(styrene-Co-Ethylacrylate) Shells for Thermal Energy Storage.” Applied Energy 150 (2015): 335–40. [37] Sun, Dan, and Lijiu Wang. “Utilization of Paraffin/expanded Perlite Materials to Improve Mechanical and Thermal Properties of Cement Mortar.” Construction and Building Materials 101 (2015): 791–96 [38] Lu, Zeyu et al. “Preparation and Characterization of Expanded Perlite/paraffin Composite as Form-Stable Phase Change Material.” Solar Energy 108 (2014): 460–66. [39] Munteanu, S. B., C. Vasile, P. Poni, Alley Ro, and Ia¡ I. Romania. “Spectral and Thermal Characterization of Styrene- Butadiene Copolymers with Different Architectures.” Journal of Optoelectronics and Advanced Materials 7(6) (2005): 3135–48. [40] Karaipekli, Ali, and Ahmet Sari. “Development and Thermal Performance of Pumice/ Organic PCM/ Gypsum Composite Plasters for Thermal Energy Storage in Buildings.” Solar Energy Materials and Solar Cells 149 (2016): 19–28. [41] Anbalagan, G., S. Mukundakumari, K. Sakthi Murugesan, and S. Gunasekaran. “Infrared, Optical Absorption, and EPR Spectroscopic Studies on Natural Gypsum.” Vibrational Spectroscopy 50(2) (2009): 226–30. [42] Mandal, Pradip K., and Tanuj K. Mandal. “Anion Water in Gypsum (CaSO4.2H2O) and Hemihydrate (CaSO4.1/2H2O).” Cement and Concrete Research 32(2) (2002): 313–16. [43] Trigui, Abdelwaheb, Mustapha Karkri, and Igor Krupa. “Thermal Conductivity and Latent Heat Thermal Energy Storage Properties of LDPE/wax as a Shape-Stabilized Composite Phase Change Material.” Energy Conversion and Management 77 (2014): 586–96. [44] Khadiran, Tumirah, Mohd Zobir Hussein, Zulkarnain Zainal, and Rafeadah Rusli. “Activated Carbon Derived from Peat Soil as a Framework for the Preparation of Shape-Stabilized Phase Change Material.” Energy 82 (2015): 468–78