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Synthesis and characterization of ditetradecyl succinate and dioctadecyl succinate as novel phase change materials for thermal energy storage
Solar Energy Materials and Solar Cells 200 (2019) 110006
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Solar Energy Materials and Solar Cells journal homepage: www.elsevier.com/locate/solmat
Synthesis and characterization of ditetradecyl succinate and dioctadecyl succinate as novel phase change materials for thermal energy storage
T
Derya Kahraman Döğüşcü Gaziosmanpasa University, Science and Letter Faculty, Department of Chemistry, 60250, Tokat, Turkey
ARTICLE INFO
ABSTRACT
Keywords: Succinic acid Tetradecanol Octadecanol Ditetradecyl succinate Dioctadecyl succinate Phase change material Thermal energy storage
This paper deals with the synthesis, characterization, thermal properties and thermal reliability of 1-tetradecanol and 1-octadecanol-succinic acid esters as a novel solid–liquid phase change materials (PCM) for thermal energy storage (TES). Ditetradecyl succinate (DTS) and dioctadecyl succinate (DOS) were synthesized by using succinic acid and excessive amount of fatty alcohol under vacuum and without catalyst. The esterification reaction yield was found above 95%. High purity ester compounds were characterized structurally by 1H nuclear magnetic resonance (1HNMR) and fourier transform infrared (FT-IR) spectroscopy techniques as thermophysical properties were investigated using a differential scanning calorimeter (DSC) and a thermogravimetric analyzer (TGA). DSC method was exploited for determination of phase change temperature, enthalpy, total enthalpy and specific heat (Cp) of DTS and DOS. Thermophysical properties of the produced esters were similar to fatty alcohols. Phase change temperatures and enthalpies were slightly lower than those of pristine fatty alcohols which were explained by the succinate distortion replaced by hydrogen bonding interactions. The DSC analyses pointed out that the phase change temperatures of TDS for heating period were between 47 °C and 46 °C as corresponding enthalpy for cooling period was between 202.4 and 197.5 Jg-1 respectively. The phase change temperature and enthalpy of DOS were between 64 °C and 63 °C and 194.9 and 191.7 Jg-1 respectively. In addition, the thermal cycling test including 1000 accelerated cyclings was conducted to determine the thermal reliability of the synthesized PCMs and structural and thermal consistency of the material were checked by post FT-IR and DSC analysis. Morphology and thermal endurance limits of the DTS and DOS were also investigated using POM and TGA respectively. Based on the results, it was concluded that the synthesized novel PCMs had considerable potential due to their satisfactory thermal properties, thermal reliability and stability.
1. Introduction Renewable energy sources need to be used more effectively because of rising green gas emissions and fuel prices and decreasing natural energy resources for this reason thermal energy storage (TES) materials have still to be improved for effective utilization [1,2]. TES is a very important contribution by reducing the energy need for energy applications such as solar energy, cooling or heating buildings, industrial waste heat systems and geothermal energy [3–6]. TES can absorb or release energy in the constant temperature, lower volume change vapour pressure by using phase change materials (PCMs) which work as latent heat storage unit [4–6]. PCMs are advantageous among all due to provide high heat storage capacity, small unit size and isothermal behavior during heat transfer processes. According to the phase change type, PCM can be classified to be four groups: solid-solid, solid-liquid, solid-gas, and liquid–gas [7]. Solid-liquid PCMs have high heat storage capacity and use of solid-liquid PCMs
in thermal energy storage systems have shown to be economically attractive. Thermal storage capacity and engineering profile are major parameters in the selection of efficient TES. The design of TES systems is important for performance of heat transportation and deposition however, designs are not the whole solution for economic attractiveness and technical reliability of the systems. Therefore, PCM selection is important in the heat deposition properties and sustainability usage [8]. PCMs are described by their melting/solidification temperatures and phase change enthalpy values [9]. Besides, there are some other additional properties for a long-time usage PCM like as congruent phase change, high rate of nucleation to avoid super-cooling during phase change and high specific heat values provide sensible heat storage capability in terms of sensible heat [10,11]. Chemical stability, non flammable, non explosive, non toxic and non corrosiveness should be having other characteristics for technical safety and durability of the energy storage systems [12].
E-mail address: [email protected]. https://doi.org/10.1016/j.solmat.2019.110006 Received 6 July 2018; Received in revised form 3 November 2018; Accepted 13 June 2019 Available online 25 June 2019 0927-0248/ © 2019 Elsevier B.V. All rights reserved.
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Fig. 1. Synthetic scheme of DTS and DOS.
Organic PCMs, inorganic PCMs and their mixtures at various ratios have been used for lots of TES applications [13,14]. Among the inorganic PCMs, salts hydrated, have some exterior properties for TES systems because of their comparatively high thermal conductivity, high latent heat capacity, and reasonable price compared to organic PCMs. But, phase segregation, corrosiveness and high supercooling should be solved for direct utilization. For this reasons, organic PCMs which have much better chemical and thermal stability, good thermal reliability and non corrosive have been preferred. In the literature, fatty acid esters have recently been reported in many papers because of their high volumetric storage density, insignificant supercooling gradient, excellent thermal reliability after accelerated thermal cyclings and they can be produced by a simple experimental procedure [15]. Aydın prepared a series of ditetradecyldecanedioate using 1-tetradecanol and one of fatty acids; tetradecanedioic acid, dodecanedioic acid, decanedioic acid for solar TES applications and characterized them structurally and thermally [8]. Aydın and Okutan synthesized some other esters by condensation reaction of 1-tetradecanol with the lauric, myristic, palmitic, stearic and arachidic acids [16] or tridecanoic, 1-pentadecanoic, 1-heptadecanoic and 1-nonadecanoic acids [17] under vacuum and without catalyst. They found that the fatty acid esters worked in temperature ranges of 38°C–53 °C and 40°C–50 °C, respectively and they were thermally stable after 1000 thermal cycle. In another work, mathematical correlations were studied to estimate the thermal properties of the homologous series of high fatty acid esters [18]. Wi et al. studied shape stabilized PCMs using organic fatty acid esters derived from coconut and palm oil with exfoliated graphite nanoplatelets using the vacuum impregnation method for to develop thermal conductivity and fire retardant properties [19]. Cabus et al. investigated that synthesis, morphology and phase change properties of diesters from 1,4-butanediol with palmitic, stearic, and behenic acid and found that synthesized PCMs had crystal content at over 90% and melting enthalpy over 180 Jg-1 [20]. Sarı et al. synthesized galactitol hexapalmitate and galactitol hexastearate using esterification reaction with acid a catalyst and performed structural characterization by FT-IR, 1HNMR, DSC, and TG analysis [21]. Sarı and Biçer prepared galactitol hexamyristate and galactitol hexalaurate fatty acid esters into building materials such as diatomite, perlite and vermiculite to be form stable composites PCMs for thermal energy storage application like as cooling and solar space heating in buildings [22].
Erythritol tetrastearate and erythritol tetrapalmitate were synthesized and prepared as form stable materials in gypsum and cement. Both PCM groups were tested in terms of their structural and thermophysical properties for validation as TES materials [23,24]. Due to these advantages of fatty acid esters, fatty alcohols of ntetradecanol and n-octadecanol were intentionally esterified as novel fatty alcohol esters using succinic acid. In this regards, these esters have been produced for the first time. Fatty alcohols are not stable under air conditions. They may degrade easily and cannot be used as stable PCMs in TES applications. Esterification converts them stable materials and therefore useable PCMs. In this work these diester compounds were characterized chemically for the provement of the reaction and thermally for the applicability as TES materials. 2. Experimental 2.1. Materials The diesters of dicarboxylicacids (ditetradecylsuccinate (TDS) and dioctadecylsuccinate (DOS)) were synthesized by using 1-tetradecanol (Aldrich 97%), 1-octadecaol (Aldrich 99%) and succinic acid (Alfa Easer 99+%)without further purification of the precursors. For the purification of TDS and DOS, acetone and ethanol from Merck Company were used as crystallization solvents. 2.2. Synthesis For the synthesis of TDS and DOS from fatty alcohols and succinic acid, the esterification reaction of fatty alcohols was performed [15]. The esterification reaction is carried out under vacuum without a solvent and without any catalyst, instead of the commonly used acidcatalyzed Fischer esterification. Stoichiometrical amount of succinic acid and 1-tetradecanol or 1-octadecanol at slightly excessive amounts were melted in a 100 mL polytetrafluoroethylene valve tap conical twonecked flask which is connected to a vacuum motor under 2–3 mmHg pressure and at 140–150 °C temperature. Reaction was mixed by using a magnetic stirrer during the synthesis. At the end of 6 h, TDS and DOS were purified with use of acetone and ethanol to remove fatty alcohol residuals remaining from the reaction. The synthetic scheme of TDS and DOS were given in Fig. 1. The yield of the process was found above 95% 2
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for both of the synthesis. 2.3. Characterization The structural characterization of TDS and DOS was performed by using Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (1HNMR) techniques. FT-IR spectra were recorded on a JASCO 430 (Japan) spectrometer in the wavenumber range of 4000 to 400 cm−1. The 1HNMR analyses were performed with a NMR spectrometer (AVANCE III 400 MHz, Bruker) using CDCl3 as solvent. Chemical shifts were saved in ppm units and tetramethylsilane (TMS) was used as an internal reference standard. Netzsch DSC214 Polyma model differential scanning calorimetry (DSC) instrument calibrated with an indium standard was exploited for determination of thermal characteristics like phase change temperature, melting-crystallization enthalpy and total enthalpy. The measurements were carried out under inert N2 atmosphere at a flow rate of 60 mL/min and in the temperature range of 0 °C–80 °C at a heating-cooling rate of 1 °C min−1. The DSC instrument calibrated with sapphire internal standard for specific heat (Cp) analyses was also used to determine the Cp of the fatty alcohols and dicarboxylic acid esters in the same conditions of DSC measurement. Thermal stability, decomposition behavior, onset weight loss temperatures of the novel PCMs were determined using Seteram TG-DTA/DSC Thermogravimetric analyzer at a scanning rate of 10 °C min−1 in a static air atmosphere. Calcium oxalate was used to calibrate TGA instrument from 35 to 500 °C at a heating rate of 10 °C min−1 in a static air atmosphere. Crystal morphology of fatty alcohols and dicarboxylic acid esters were monitored with Leica DM EP model (Germany, 2010) polarize optical microscope (POM). A thermal cycling test was carried out 1000 times to determine the thermal reliability of synthesized PCMs using a thermal cycler (BIOER TC-25/H model). After thermal cycling, FT-IR and DSC analyses were also repeated to determine chemical and thermal stability of dicarboxylic acid esters. Fig. 2. FT-IR spectra of succinic acid, 1-tetradecanol, 1-octadecanol, DTS and DOS.
3. Results and discussion 3.1. The structural characterization of the dicarboxylic acid esters
esters were given in Fig. 4 and the data from DSC measurements were tabulated in Table 1. As shown in the Table 1, 1-tetradecanol and 1octadecanol had 2 close phase transitions for solid-solid phase transition and for melting. Because that they were generally overlapping, it was very difficult to report exact melting transition temperature. On the other hand these peaks distribute better during cooling and reporting onset is possible for crystallization. From the curves, it was seen that 1tetradecanol melted and crystallized at 36 and 35 °C respectively as 1octadecanol melted and crystallized at 50 and 56 °C respectively. The enthalpy of heating and cooling were 236.2 and 234.0 Jg-1 respectively for 1-tetradecanol and 252.3 and 254.6 Jg-1 for 1-octadecanol respectively. The melting and solidifications temperatures of DTS and DOS were 47 and 46 °C for DTS respectively and 64 and 63 °C for DOS respectively. The phase change temperature and enthalpy values of DTS and DOS were slightly lower than those of precursor fatty acids, which was consistent with the literature for fatty acid and fatty alcohol esters. The middle segment of the ester molecules distort crystallinity more than hydrogen bonding segments of the precursors. There are also solidsolid phase transitions for DTS and DOS. However these solid-solid transitions occur with a very low enthalpy. On the other hand, DTS and DOS were having enthalpy above 190 Jg-1 which was sufficiently considerable for a TES material for solar applications. The total enthalpy values of synthesized dicarboxylic acids esters were calculated for a 0 °C–80 °C temperature interval as shown in Fig. 5. The parts of the curves outside the phase transition regions showed that sensible heat storage capacities of the PCMs. The total enthalpy of novel organic PCMs were found 244 J g−1 and 231 J g−1 for DTS and DOS respectively. As a result of total enthalpy calculation, it was seen that there was almost no overcooling.
The dicarboxylic acid esters compounds were characterized by FTIR and 1HNMR spectroscopy measurements to confirm the chemical structure of DTS and DOS. Fig. 2 indicated FT-IR spectra of precursors and synthesized diester. The –OH vibration bands of 1-tetradecanol, 1octadecanol and succinic acid which became invisible in the esters were observed in the range of 3100–3550 cm−1. This peak proved that the hydroxyl groups of fatty alcohol and succinic acid had converted to ester bond and esterification reactions were completed. The carbonyl stretching peaks of succinic acid, ditetradecyl succinate and dioctadecyl succinate observed at 1697 cm−1, 1724 cm−1 and 1726 cm−1, respectively, also verify the ester bond formation. The peaks at around 28472955 cm−1 and 1310-1370 cm−1 were assigned to –CH2 stretching and bending vibration peaks of the materials. Besides C–O–C bonds in the ditetradecyl succinate and dioctadecyl succinate were recorded at 1070 and 1100 cm−1, respectively. The 1HNMR spectra of DTS and DOS were given in Fig. 3 with dicarboxylic acid esters’ chemical structures. The presented peaks were assigned to the protons of (CDCl3, ppm) –CH3 at about δ = 0.9 (t, J = 6.7 Hz, 6H), –(CH2)11– and –(CH2)15 at about δ = 1.20–1.50 (m, 44H or 60H), labeled with c at about δ = 1.60–1.68 (m, 4H), –COO (CH2)2COO- (labeled with d) at about δ = 2.64 (s, 4H) and labeled with e at about δ = 4.10 (t, J = 6.8 Hz, 4H) for dicarboxylic acid esters. The chemical shifts and number of protons were in good agreement with dicarboxylic acid esters. 3.2. Thermal characterization of the dicarboxylic acid esters DSC thermogram of the pure fatty alcohols and dicarboxylic acid 3
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Fig. 3. 1H NMR spectra of DTS and DOS.
Fig. 4. DSC curves of 1-tetradecanol, DTS, 1-octadecanol, and DOS.
In addition to DSC data, specific heat values of fatty alcohols, DTS and DOS were recorded with a special technique as shown in Fig. 6. Cp is well known that it goes to infinity during phase changes. The reason for not seeing is the time restriction during heating. Fig. 6 shows two peaks (that should go to infinity theoretically) for solid-solid and solidliquid phase changes. Cp values of precursor fatty alcohol and DTS and DOS were tabulated in Table 2. In literature, most of researcher focused
of only phase change temperature and latent heat capacity of PCMs. The specific heat has a direct effect on thermal energy storage when latent heat storage capacity is calculated. It contributes to the total amount of heat as sensibly stored heat.
4
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Table 1 TES characteristics of 1-tetradecanol, 1-octadecanol, DTS and DOS. Materials
Melting temperature (°C)
Melting enthalpy (Jg−1)
Freezing temperature (°C)
Freezing enthalpy (Jg−1)
1-tetradecanol 1-octadecanol DTS DOS
36 50 47 64
236.2 252.3 202.4 194.9
35 56 46 63
−234.0 −254.6 197.5 191.7
Fig. 7. TGA curves of DTS and DOS Table 3 Thermal endurance limits of DTS and DOS. Materials
Degradation temperature (°C)
Weight loss [%]
DTGmax
DTS DOS
354.6–396.2 380.6–428.9
93.2 94.4
390.8 413.8
3.3. Thermal endurance of the dicarboxylic acid esters Fig. 5. Total enthalpy versus temperature curves of 1-tetradecanol, DTS, 1octadecanol, and DOS.
TGA data is important to determine the maximum temperature at which material can withstand without chemical decomposition. The onset decomposition temperatures are important for utilization of PCMs because the first of the degradations is boiling of organic compounds. TGA curves of DTS and DOS were shown in Fig. 7 as TGA data was tabulated in Table 3. DTS and DOS had single decomposition step starting at onset decomposition temperatures of 354 and 380 °C, respectively. Thus, these materials can easily withstand ambient temperatures for solar applications. It is well known that esters with even carbon number show significant increase in thermal stability with increasing carbon number up to 14–20 at which the increase in fatty alcohol chain length promotes the durability of the material. 3.4. POM investigation of the dicarboxylic acid esters Fig. 8 shows the POM images of pristine fatty alcohols and dicarboxylic acid esters below phase transition temperatures. It can be followed up that both fatty alcohols and produced dicarboxylic acid esters had slightly different phase appearances. 3.5. Thermal reliability of the dicarboxylic acid esters
Fig. 6. Cp versus temperature curves of 1-tetradecanol, 1-octadecanol, DTS and DOS.
Thermal reliability and chemical stability are major parameters to forecast the lifetime of PCMs for a TES system. Therefore, it is expected
Table 2 Cp values of 1-tetradecanol, 1-octadecanol, DTS and DOS.
Cp (J/(g*K))
Temperature (°C)
1-tetradecanol
1-octadecanol
TDS
DOS
(-10 °C) (0 °C) (10 °C) before solid-solid phase change temperature before solid-liquid phase change temperature (80 °C) (100 °C)
1.49 1.55 1.63
1.53 1.57 1.62
6.20 (36 °C) 2.33 2.33
2.45 (50 °C) 2.37 2.34
1.92 2.08 2.21 2.22 (23 °C) 21.24 (47 °C) 2.28 2.23
1.53 1.59 1.67 1.93 (29 °C) 18.13 (64 °C) 2.03 2.01
5
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Fig. 8. POM Images of n-tetradecanol (A), DTS (B), n-octadecanol (C), DOS (D).
Fig. 9. DSC thermograms of DTS and DOS before and after 1000 accelerated thermal cycling.
that a good PCM would not change its chemical structure, phase change enthalpy and working temperature at the end of a large number of thermal cyclings. The thermal reliability and chemical stability of the dicarboxylic acid esters were determined after 1000 times accelerated melting and freezing cycles with the help of DNA thermal cycler. The structure and enthalpy were tested for consistency with FT-IR and DSC measurements respectively. Figs. 9 and 10 showed DSC and FT-IR curves of DTS and DOS before and after thermal cyclings as Table 4 showed the DSC data of DTS and DOS before and after thermal cycling. As clearly seen from Table 4 that, onset melting temperature of TDS was changed very slightly, as that of crystallization was 2 °C different. Melting temperature of DOS was found 3.1% lessened as freezing temperature did not change after 1000 thermal cycles. In addition, melting and freezing phase change enthalpies of DTS has changed only 3.5% and 2.3% with respect to uncycled whereas melting and freezing phase change enthalpies of DOS were found 5.9% and 3.52% lower at the end of 1000 thermal cycles. These little changes in the phase change temperature and latent heat
capacity means that synthesized PCMs had good thermal reliability for thermal energy storage applications after 1000 heating-cooling cycles. On the other hand, as seen in the FT-IR spectra, there is no change observed in the spectral positions of characteristic chemical groups of the synthesized PCMs after 1000 thermal cycles. Table 5 tabulates the recently synthesized fatty acid esters with melting temperatures and enthalpy. It is clear that the melting enthalpies of fatty alcohol esters are as much as the fatty acid esters are. Also the temperature values are similar as compared to the corresponding precursors. As a result, fatty alcohols can be validated as potential PCMs for solar applications. 4. Conclusion DTS and DOS were synthesized as novel PCMs from succinic acid and fatty alcohols; 1-tetradecanol and 1-octadecanol respectively and characterized by using FTIR and NMR spectroscopy techniques structurally. DSC analysis and thermal cycling tests showed that DTS and 6
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Table 5 Some fatty acid esters and their corresponding melting temperature and enthalpy values. Materials
Melting temperature (°C)
Melting enthalpy (Jg−1)
Xylitol pentastearate [7] Xylitol pentapalmitate [7] Ditetradecyl-1,10-decanedioate [8] Ditetradecyl-1,12-decanedioate [8] Ditetradecyl-1,14-decanedioate [8] Myristyl laurate [16] Myristyl myristate [16] Myrsityl palmitate [16] Myristyl stearate [16] Myristyl arcihidate [16] Tetradecyl tridecanoate [17] Tetradecyl pentadecanoate [17] Tetradecyl heptadecanoate [17] Tetradecyl nonadecanoate [17] Stearyl laurate [18] Stearyl myristate [18] Stearyl palmitate [18] Stearyl stearate [18] Stearyl arcihidate [18]
32.35 18.75 50.78
205.65 170.05 202.17
54.88
205.11
57.36
207.07
38.05 41.60 48.03 49.58 52.84 40.01 45.43 46.68 50.19 42.21 48.86 57.34 59.22 64.96
207.90 210.43 213.85 221.80 201.34 207.89 214.81 217.19 203.23 201.03 203.53 219.74 214.93 226.12
Acknowledgements The author would like to thank Gaziosmanpaşa University Polymer Research Laboratory for the materials and facilities. Appendix A. Supplementary data Fig. 10. FT-IR spectra of DTS and DOS before and after 1000 accelerated thermal cycling.
Supplementary data to this article can be found online at https:// doi.org/10.1016/j.solmat.2019.110006.
Table 4 Thermal energy storage characteristics of DTS and DOS before and after thermal cycling. Materials
Melting temperature (°C)
Melting enthalpy (Jg−1)
Freezing temperature (°C)
Freezing enthalpy (Jg−1)
DTS DOS DTS ATC DOS ATC
47 64 48 63
202.4 194.9 209.4 206.3
46 63 48 63
197.5 191.7 202.0 194.8
References [1] N. Zhang, Y. Yuan, X. Cao, Y. Du, Z. Zhang, Y. Gui, Latent heat thermal energy storage systems with solid–liquid phase change materials: a review, Adv. Eng. Mater. 20 (6) (2018) 1–30. [2] M.H. Abokersh, M. Osman, O. El‐Baz, M. El‐Morsi, O. Sharaf, Review of the phase change material (PCM) usage for solar domestic water heating systems (SDWHS), Int. Energy Storage 42 (2) (2018) 329–357. [3] X. Huang, G. Alva, Y. Jia, G. Fang, Morphological characterization and applications of phase change materials in thermal energy storage: a review, Renew. Sustain. Energy Rev. 72 (2017) 128–145. [4] H. Akeiber, P. Nejat, M.Z.A. Majid, M.A. Wahid, F. Jomehzadeh, I.Z. Famileh, J.K. Calautit, B.R. Hughes, S.A. Zaki, A review on phase change material (PCM) for sustainable passive cooling in building envelopes, Renew. Sustain. Energy Rev. 60 (2016) 1470–1479. [5] B. Xu, P. Li, C. Chan, Application of phase change materials for thermal energy storage in concentrated solar thermal power plants: a review to recent developments, Appl. Energy 160 (2015) 286–307. [6] S.E. Kalnæsa, B.P. Jelle, Phase change materials and products for building applications: a state-of-the-art review and future research opportunities, Energy Build. 94 (2015) 150–176. [7] A. Biçer, A. Sarı, Synthesis and thermal energy storage properties of xylitol pentastearate and xylitol pentapalmitate as novel solid-liquid PCMs, Sol. Energy Mater. Sol. Cells 102 (2012) 125–130. [8] A.A. Aydın, Diesters of high-chain dicarboxylic acids with 1-tetradecanol as novel organic phase change materials for thermal energy storage, Sol. Energy Mater. Sol. Cells 104 (2012) 102–108. [9] H. Mehling, L.F. Cabeza, Heat and Cold StorageWith PCM:an up to Date Introduction into Basics and Applications, Springer, Berlin, Germany, 2008. [10] A. Sharma, V.V. Tyagi, C.R. Chen, D. Buddhi, Review on thermal energy storage with phase change materials and applications, Renew. Sustain. Energy Rev. 13 (2009) 318–345. [11] R. Baetens, B.P. Jelle, A. Gustavse, Phase change materials for building applications: a state-of-the-art review, Energy Build. 42 (9) (2010) 1361–1368. [12] D. Zhou, C.Y. Zhao, Y. Tian, Review on thermal energy storage with phase change materials (PCMs) in building applications, Appl. Energy 92 (2012) 593–605. [13] M. Mazman, L.F. Cabeza, H. Mehling, M. Nogues, H. Evliya, H.Ö. Paksoy, Utilization of phase change materials in solar domestic hot water systems, Renew. Energy 34 (2009) 1639–1643.
DOS can be used as novel PCMs due to their suitable phase change temperatures, LHTES capacity for thermal energy storage applications and structural and thermal consistency upon thermal cycling. Besides DTS and DOS were found stable up to extreme temperatures compared to ambient according to the TGA measurements. Latent heat energy storage capacity of DTS and DOS were found slightly lower than pristine fatty alcohols. DTS and DOS had phase change temperatures of 47 °C and 64 °C for melting respectively and 46 °C and 63 °C for solidification respectively. These phase transition temperatures are suitable for solar thermal applications. The enthalpy values are of 14% less than the precursor for DTS as it is of 23% less for DOS. It was attributed to distorted crystallinity in the structure due to succinate group. It is traditional to ester materials produced from fatty acids or alcohols. DTS and DOS are odorless, noncorrosive and stable. They had also considerable thermal storage capacity. And therefore they are better alternatives to fatty acids and fatty alcohols as solar thermal storage materials.
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D. Kahraman Döğüşcü [14] Z. Zhou, Z. Zhang, J. Zuo, K. Huang, L. Zhang, Phase change materials for solar thermal energy storage in residential buildings in cold climate, Renew. Sustain. Energy Rev. 48 (2015) 692–703. [15] F. Baykut, A. Aydın, The synthesis and physical properties of the homologous series of fatty acids' esters, Reveu De La Faculte Des Sciences De L’Universite D’Istanbul Serie C 34 (1969) 119–148. [16] A.A. Aydın, H. Okutan, High-chain fatty acid esters of myristyl alcohol with even carbon number: novel organic phase change materials for thermal energy storage-1, Sol. Energy Mater. Sol. Cells 95 (2011) 2752–2762. [17] A.A. Aydın, H. Okutan, High-chain fatty acid esters of myristyl alcohol with even carbon number: novel organic phase change materials for thermal energy storage-2, Sol. Energy Mater. Sol. Cells 95 (2011) 2417–2423. [18] A.A. Aydın, High-chain fatty acid esters of 1-octadecanol as novel organic phase change materials and mathematical correlations for estimating the thermal properties of higher fatty acid esters' homologous series, Sol. Energy Mater. Sol. Cells 113 (2013) 44–51. [19] S. Wi, J. Seo, S.G. Jeong, S.J. Chang, Y. Kang, S. Kim, Thermal properties of shapestabilized phase change materials using fatty acid ester and exfoliated graphite
[20] [21] [22] [23] [24]
8
nanoplatelets for saving energy in buildings, Sol. Energy Mater. Sol. Cells 143 (2015) 168–1731. S. Cabus, K. Bogaerts, J.V. Mechelen, M. Smet, B. Goderis, Monotropic polymorphism in ester-based phase change materials from fatty acids and 1,4-butanediol, Cryst. Growth Des. 13 (8) (2013) 3438–3446. A. Sarı, A. Biçer, Ö. Lafcı, M. Ceylan, Galactitol hexa stearate and galactitol hexa palmitate as novel solid-liquid phase change materials for thermal energy storage, Sol. Energy 85 (2011) 2061–2071. A. Sarı, A. Biçer, Thermal energy storage properties and thermal reliability of some fatty acid esters/building material compositesas novel form-stable PCMs, Sol. Energy Mater. Sol. Cells 101 (2012) 114–122. A. Sari, R. Eroglu, A. Biçer, A. Karaipekli, Synthesis and thermal energy storage properties of erythritol tetrastearate and erythritol tetrapalmitate, Chem. Eng. Technol. 34 (1) (2011) 87–92. A. Karaipekli, A. Sarı, Preparation and characterization of fatty acid ester/building material composites for thermal energy storage in buildings, Energy Build. 43 (2011) 1952–1959.
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Solar Energy Materials and Solar Cells journal homepage: www.elsevier.com/locate/solmat
Synthesis and characterization of ditetradecyl succinate and dioctadecyl succinate as novel phase change materials for thermal energy storage
T
Derya Kahraman Döğüşcü Gaziosmanpasa University, Science and Letter Faculty, Department of Chemistry, 60250, Tokat, Turkey
ARTICLE INFO
ABSTRACT
Keywords: Succinic acid Tetradecanol Octadecanol Ditetradecyl succinate Dioctadecyl succinate Phase change material Thermal energy storage
This paper deals with the synthesis, characterization, thermal properties and thermal reliability of 1-tetradecanol and 1-octadecanol-succinic acid esters as a novel solid–liquid phase change materials (PCM) for thermal energy storage (TES). Ditetradecyl succinate (DTS) and dioctadecyl succinate (DOS) were synthesized by using succinic acid and excessive amount of fatty alcohol under vacuum and without catalyst. The esterification reaction yield was found above 95%. High purity ester compounds were characterized structurally by 1H nuclear magnetic resonance (1HNMR) and fourier transform infrared (FT-IR) spectroscopy techniques as thermophysical properties were investigated using a differential scanning calorimeter (DSC) and a thermogravimetric analyzer (TGA). DSC method was exploited for determination of phase change temperature, enthalpy, total enthalpy and specific heat (Cp) of DTS and DOS. Thermophysical properties of the produced esters were similar to fatty alcohols. Phase change temperatures and enthalpies were slightly lower than those of pristine fatty alcohols which were explained by the succinate distortion replaced by hydrogen bonding interactions. The DSC analyses pointed out that the phase change temperatures of TDS for heating period were between 47 °C and 46 °C as corresponding enthalpy for cooling period was between 202.4 and 197.5 Jg-1 respectively. The phase change temperature and enthalpy of DOS were between 64 °C and 63 °C and 194.9 and 191.7 Jg-1 respectively. In addition, the thermal cycling test including 1000 accelerated cyclings was conducted to determine the thermal reliability of the synthesized PCMs and structural and thermal consistency of the material were checked by post FT-IR and DSC analysis. Morphology and thermal endurance limits of the DTS and DOS were also investigated using POM and TGA respectively. Based on the results, it was concluded that the synthesized novel PCMs had considerable potential due to their satisfactory thermal properties, thermal reliability and stability.
1. Introduction Renewable energy sources need to be used more effectively because of rising green gas emissions and fuel prices and decreasing natural energy resources for this reason thermal energy storage (TES) materials have still to be improved for effective utilization [1,2]. TES is a very important contribution by reducing the energy need for energy applications such as solar energy, cooling or heating buildings, industrial waste heat systems and geothermal energy [3–6]. TES can absorb or release energy in the constant temperature, lower volume change vapour pressure by using phase change materials (PCMs) which work as latent heat storage unit [4–6]. PCMs are advantageous among all due to provide high heat storage capacity, small unit size and isothermal behavior during heat transfer processes. According to the phase change type, PCM can be classified to be four groups: solid-solid, solid-liquid, solid-gas, and liquid–gas [7]. Solid-liquid PCMs have high heat storage capacity and use of solid-liquid PCMs
in thermal energy storage systems have shown to be economically attractive. Thermal storage capacity and engineering profile are major parameters in the selection of efficient TES. The design of TES systems is important for performance of heat transportation and deposition however, designs are not the whole solution for economic attractiveness and technical reliability of the systems. Therefore, PCM selection is important in the heat deposition properties and sustainability usage [8]. PCMs are described by their melting/solidification temperatures and phase change enthalpy values [9]. Besides, there are some other additional properties for a long-time usage PCM like as congruent phase change, high rate of nucleation to avoid super-cooling during phase change and high specific heat values provide sensible heat storage capability in terms of sensible heat [10,11]. Chemical stability, non flammable, non explosive, non toxic and non corrosiveness should be having other characteristics for technical safety and durability of the energy storage systems [12].
E-mail address: [email protected]. https://doi.org/10.1016/j.solmat.2019.110006 Received 6 July 2018; Received in revised form 3 November 2018; Accepted 13 June 2019 Available online 25 June 2019 0927-0248/ © 2019 Elsevier B.V. All rights reserved.
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Fig. 1. Synthetic scheme of DTS and DOS.
Organic PCMs, inorganic PCMs and their mixtures at various ratios have been used for lots of TES applications [13,14]. Among the inorganic PCMs, salts hydrated, have some exterior properties for TES systems because of their comparatively high thermal conductivity, high latent heat capacity, and reasonable price compared to organic PCMs. But, phase segregation, corrosiveness and high supercooling should be solved for direct utilization. For this reasons, organic PCMs which have much better chemical and thermal stability, good thermal reliability and non corrosive have been preferred. In the literature, fatty acid esters have recently been reported in many papers because of their high volumetric storage density, insignificant supercooling gradient, excellent thermal reliability after accelerated thermal cyclings and they can be produced by a simple experimental procedure [15]. Aydın prepared a series of ditetradecyldecanedioate using 1-tetradecanol and one of fatty acids; tetradecanedioic acid, dodecanedioic acid, decanedioic acid for solar TES applications and characterized them structurally and thermally [8]. Aydın and Okutan synthesized some other esters by condensation reaction of 1-tetradecanol with the lauric, myristic, palmitic, stearic and arachidic acids [16] or tridecanoic, 1-pentadecanoic, 1-heptadecanoic and 1-nonadecanoic acids [17] under vacuum and without catalyst. They found that the fatty acid esters worked in temperature ranges of 38°C–53 °C and 40°C–50 °C, respectively and they were thermally stable after 1000 thermal cycle. In another work, mathematical correlations were studied to estimate the thermal properties of the homologous series of high fatty acid esters [18]. Wi et al. studied shape stabilized PCMs using organic fatty acid esters derived from coconut and palm oil with exfoliated graphite nanoplatelets using the vacuum impregnation method for to develop thermal conductivity and fire retardant properties [19]. Cabus et al. investigated that synthesis, morphology and phase change properties of diesters from 1,4-butanediol with palmitic, stearic, and behenic acid and found that synthesized PCMs had crystal content at over 90% and melting enthalpy over 180 Jg-1 [20]. Sarı et al. synthesized galactitol hexapalmitate and galactitol hexastearate using esterification reaction with acid a catalyst and performed structural characterization by FT-IR, 1HNMR, DSC, and TG analysis [21]. Sarı and Biçer prepared galactitol hexamyristate and galactitol hexalaurate fatty acid esters into building materials such as diatomite, perlite and vermiculite to be form stable composites PCMs for thermal energy storage application like as cooling and solar space heating in buildings [22].
Erythritol tetrastearate and erythritol tetrapalmitate were synthesized and prepared as form stable materials in gypsum and cement. Both PCM groups were tested in terms of their structural and thermophysical properties for validation as TES materials [23,24]. Due to these advantages of fatty acid esters, fatty alcohols of ntetradecanol and n-octadecanol were intentionally esterified as novel fatty alcohol esters using succinic acid. In this regards, these esters have been produced for the first time. Fatty alcohols are not stable under air conditions. They may degrade easily and cannot be used as stable PCMs in TES applications. Esterification converts them stable materials and therefore useable PCMs. In this work these diester compounds were characterized chemically for the provement of the reaction and thermally for the applicability as TES materials. 2. Experimental 2.1. Materials The diesters of dicarboxylicacids (ditetradecylsuccinate (TDS) and dioctadecylsuccinate (DOS)) were synthesized by using 1-tetradecanol (Aldrich 97%), 1-octadecaol (Aldrich 99%) and succinic acid (Alfa Easer 99+%)without further purification of the precursors. For the purification of TDS and DOS, acetone and ethanol from Merck Company were used as crystallization solvents. 2.2. Synthesis For the synthesis of TDS and DOS from fatty alcohols and succinic acid, the esterification reaction of fatty alcohols was performed [15]. The esterification reaction is carried out under vacuum without a solvent and without any catalyst, instead of the commonly used acidcatalyzed Fischer esterification. Stoichiometrical amount of succinic acid and 1-tetradecanol or 1-octadecanol at slightly excessive amounts were melted in a 100 mL polytetrafluoroethylene valve tap conical twonecked flask which is connected to a vacuum motor under 2–3 mmHg pressure and at 140–150 °C temperature. Reaction was mixed by using a magnetic stirrer during the synthesis. At the end of 6 h, TDS and DOS were purified with use of acetone and ethanol to remove fatty alcohol residuals remaining from the reaction. The synthetic scheme of TDS and DOS were given in Fig. 1. The yield of the process was found above 95% 2
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for both of the synthesis. 2.3. Characterization The structural characterization of TDS and DOS was performed by using Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (1HNMR) techniques. FT-IR spectra were recorded on a JASCO 430 (Japan) spectrometer in the wavenumber range of 4000 to 400 cm−1. The 1HNMR analyses were performed with a NMR spectrometer (AVANCE III 400 MHz, Bruker) using CDCl3 as solvent. Chemical shifts were saved in ppm units and tetramethylsilane (TMS) was used as an internal reference standard. Netzsch DSC214 Polyma model differential scanning calorimetry (DSC) instrument calibrated with an indium standard was exploited for determination of thermal characteristics like phase change temperature, melting-crystallization enthalpy and total enthalpy. The measurements were carried out under inert N2 atmosphere at a flow rate of 60 mL/min and in the temperature range of 0 °C–80 °C at a heating-cooling rate of 1 °C min−1. The DSC instrument calibrated with sapphire internal standard for specific heat (Cp) analyses was also used to determine the Cp of the fatty alcohols and dicarboxylic acid esters in the same conditions of DSC measurement. Thermal stability, decomposition behavior, onset weight loss temperatures of the novel PCMs were determined using Seteram TG-DTA/DSC Thermogravimetric analyzer at a scanning rate of 10 °C min−1 in a static air atmosphere. Calcium oxalate was used to calibrate TGA instrument from 35 to 500 °C at a heating rate of 10 °C min−1 in a static air atmosphere. Crystal morphology of fatty alcohols and dicarboxylic acid esters were monitored with Leica DM EP model (Germany, 2010) polarize optical microscope (POM). A thermal cycling test was carried out 1000 times to determine the thermal reliability of synthesized PCMs using a thermal cycler (BIOER TC-25/H model). After thermal cycling, FT-IR and DSC analyses were also repeated to determine chemical and thermal stability of dicarboxylic acid esters. Fig. 2. FT-IR spectra of succinic acid, 1-tetradecanol, 1-octadecanol, DTS and DOS.
3. Results and discussion 3.1. The structural characterization of the dicarboxylic acid esters
esters were given in Fig. 4 and the data from DSC measurements were tabulated in Table 1. As shown in the Table 1, 1-tetradecanol and 1octadecanol had 2 close phase transitions for solid-solid phase transition and for melting. Because that they were generally overlapping, it was very difficult to report exact melting transition temperature. On the other hand these peaks distribute better during cooling and reporting onset is possible for crystallization. From the curves, it was seen that 1tetradecanol melted and crystallized at 36 and 35 °C respectively as 1octadecanol melted and crystallized at 50 and 56 °C respectively. The enthalpy of heating and cooling were 236.2 and 234.0 Jg-1 respectively for 1-tetradecanol and 252.3 and 254.6 Jg-1 for 1-octadecanol respectively. The melting and solidifications temperatures of DTS and DOS were 47 and 46 °C for DTS respectively and 64 and 63 °C for DOS respectively. The phase change temperature and enthalpy values of DTS and DOS were slightly lower than those of precursor fatty acids, which was consistent with the literature for fatty acid and fatty alcohol esters. The middle segment of the ester molecules distort crystallinity more than hydrogen bonding segments of the precursors. There are also solidsolid phase transitions for DTS and DOS. However these solid-solid transitions occur with a very low enthalpy. On the other hand, DTS and DOS were having enthalpy above 190 Jg-1 which was sufficiently considerable for a TES material for solar applications. The total enthalpy values of synthesized dicarboxylic acids esters were calculated for a 0 °C–80 °C temperature interval as shown in Fig. 5. The parts of the curves outside the phase transition regions showed that sensible heat storage capacities of the PCMs. The total enthalpy of novel organic PCMs were found 244 J g−1 and 231 J g−1 for DTS and DOS respectively. As a result of total enthalpy calculation, it was seen that there was almost no overcooling.
The dicarboxylic acid esters compounds were characterized by FTIR and 1HNMR spectroscopy measurements to confirm the chemical structure of DTS and DOS. Fig. 2 indicated FT-IR spectra of precursors and synthesized diester. The –OH vibration bands of 1-tetradecanol, 1octadecanol and succinic acid which became invisible in the esters were observed in the range of 3100–3550 cm−1. This peak proved that the hydroxyl groups of fatty alcohol and succinic acid had converted to ester bond and esterification reactions were completed. The carbonyl stretching peaks of succinic acid, ditetradecyl succinate and dioctadecyl succinate observed at 1697 cm−1, 1724 cm−1 and 1726 cm−1, respectively, also verify the ester bond formation. The peaks at around 28472955 cm−1 and 1310-1370 cm−1 were assigned to –CH2 stretching and bending vibration peaks of the materials. Besides C–O–C bonds in the ditetradecyl succinate and dioctadecyl succinate were recorded at 1070 and 1100 cm−1, respectively. The 1HNMR spectra of DTS and DOS were given in Fig. 3 with dicarboxylic acid esters’ chemical structures. The presented peaks were assigned to the protons of (CDCl3, ppm) –CH3 at about δ = 0.9 (t, J = 6.7 Hz, 6H), –(CH2)11– and –(CH2)15 at about δ = 1.20–1.50 (m, 44H or 60H), labeled with c at about δ = 1.60–1.68 (m, 4H), –COO (CH2)2COO- (labeled with d) at about δ = 2.64 (s, 4H) and labeled with e at about δ = 4.10 (t, J = 6.8 Hz, 4H) for dicarboxylic acid esters. The chemical shifts and number of protons were in good agreement with dicarboxylic acid esters. 3.2. Thermal characterization of the dicarboxylic acid esters DSC thermogram of the pure fatty alcohols and dicarboxylic acid 3
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Fig. 3. 1H NMR spectra of DTS and DOS.
Fig. 4. DSC curves of 1-tetradecanol, DTS, 1-octadecanol, and DOS.
In addition to DSC data, specific heat values of fatty alcohols, DTS and DOS were recorded with a special technique as shown in Fig. 6. Cp is well known that it goes to infinity during phase changes. The reason for not seeing is the time restriction during heating. Fig. 6 shows two peaks (that should go to infinity theoretically) for solid-solid and solidliquid phase changes. Cp values of precursor fatty alcohol and DTS and DOS were tabulated in Table 2. In literature, most of researcher focused
of only phase change temperature and latent heat capacity of PCMs. The specific heat has a direct effect on thermal energy storage when latent heat storage capacity is calculated. It contributes to the total amount of heat as sensibly stored heat.
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Table 1 TES characteristics of 1-tetradecanol, 1-octadecanol, DTS and DOS. Materials
Melting temperature (°C)
Melting enthalpy (Jg−1)
Freezing temperature (°C)
Freezing enthalpy (Jg−1)
1-tetradecanol 1-octadecanol DTS DOS
36 50 47 64
236.2 252.3 202.4 194.9
35 56 46 63
−234.0 −254.6 197.5 191.7
Fig. 7. TGA curves of DTS and DOS Table 3 Thermal endurance limits of DTS and DOS. Materials
Degradation temperature (°C)
Weight loss [%]
DTGmax
DTS DOS
354.6–396.2 380.6–428.9
93.2 94.4
390.8 413.8
3.3. Thermal endurance of the dicarboxylic acid esters Fig. 5. Total enthalpy versus temperature curves of 1-tetradecanol, DTS, 1octadecanol, and DOS.
TGA data is important to determine the maximum temperature at which material can withstand without chemical decomposition. The onset decomposition temperatures are important for utilization of PCMs because the first of the degradations is boiling of organic compounds. TGA curves of DTS and DOS were shown in Fig. 7 as TGA data was tabulated in Table 3. DTS and DOS had single decomposition step starting at onset decomposition temperatures of 354 and 380 °C, respectively. Thus, these materials can easily withstand ambient temperatures for solar applications. It is well known that esters with even carbon number show significant increase in thermal stability with increasing carbon number up to 14–20 at which the increase in fatty alcohol chain length promotes the durability of the material. 3.4. POM investigation of the dicarboxylic acid esters Fig. 8 shows the POM images of pristine fatty alcohols and dicarboxylic acid esters below phase transition temperatures. It can be followed up that both fatty alcohols and produced dicarboxylic acid esters had slightly different phase appearances. 3.5. Thermal reliability of the dicarboxylic acid esters
Fig. 6. Cp versus temperature curves of 1-tetradecanol, 1-octadecanol, DTS and DOS.
Thermal reliability and chemical stability are major parameters to forecast the lifetime of PCMs for a TES system. Therefore, it is expected
Table 2 Cp values of 1-tetradecanol, 1-octadecanol, DTS and DOS.
Cp (J/(g*K))
Temperature (°C)
1-tetradecanol
1-octadecanol
TDS
DOS
(-10 °C) (0 °C) (10 °C) before solid-solid phase change temperature before solid-liquid phase change temperature (80 °C) (100 °C)
1.49 1.55 1.63
1.53 1.57 1.62
6.20 (36 °C) 2.33 2.33
2.45 (50 °C) 2.37 2.34
1.92 2.08 2.21 2.22 (23 °C) 21.24 (47 °C) 2.28 2.23
1.53 1.59 1.67 1.93 (29 °C) 18.13 (64 °C) 2.03 2.01
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Fig. 8. POM Images of n-tetradecanol (A), DTS (B), n-octadecanol (C), DOS (D).
Fig. 9. DSC thermograms of DTS and DOS before and after 1000 accelerated thermal cycling.
that a good PCM would not change its chemical structure, phase change enthalpy and working temperature at the end of a large number of thermal cyclings. The thermal reliability and chemical stability of the dicarboxylic acid esters were determined after 1000 times accelerated melting and freezing cycles with the help of DNA thermal cycler. The structure and enthalpy were tested for consistency with FT-IR and DSC measurements respectively. Figs. 9 and 10 showed DSC and FT-IR curves of DTS and DOS before and after thermal cyclings as Table 4 showed the DSC data of DTS and DOS before and after thermal cycling. As clearly seen from Table 4 that, onset melting temperature of TDS was changed very slightly, as that of crystallization was 2 °C different. Melting temperature of DOS was found 3.1% lessened as freezing temperature did not change after 1000 thermal cycles. In addition, melting and freezing phase change enthalpies of DTS has changed only 3.5% and 2.3% with respect to uncycled whereas melting and freezing phase change enthalpies of DOS were found 5.9% and 3.52% lower at the end of 1000 thermal cycles. These little changes in the phase change temperature and latent heat
capacity means that synthesized PCMs had good thermal reliability for thermal energy storage applications after 1000 heating-cooling cycles. On the other hand, as seen in the FT-IR spectra, there is no change observed in the spectral positions of characteristic chemical groups of the synthesized PCMs after 1000 thermal cycles. Table 5 tabulates the recently synthesized fatty acid esters with melting temperatures and enthalpy. It is clear that the melting enthalpies of fatty alcohol esters are as much as the fatty acid esters are. Also the temperature values are similar as compared to the corresponding precursors. As a result, fatty alcohols can be validated as potential PCMs for solar applications. 4. Conclusion DTS and DOS were synthesized as novel PCMs from succinic acid and fatty alcohols; 1-tetradecanol and 1-octadecanol respectively and characterized by using FTIR and NMR spectroscopy techniques structurally. DSC analysis and thermal cycling tests showed that DTS and 6
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Table 5 Some fatty acid esters and their corresponding melting temperature and enthalpy values. Materials
Melting temperature (°C)
Melting enthalpy (Jg−1)
Xylitol pentastearate [7] Xylitol pentapalmitate [7] Ditetradecyl-1,10-decanedioate [8] Ditetradecyl-1,12-decanedioate [8] Ditetradecyl-1,14-decanedioate [8] Myristyl laurate [16] Myristyl myristate [16] Myrsityl palmitate [16] Myristyl stearate [16] Myristyl arcihidate [16] Tetradecyl tridecanoate [17] Tetradecyl pentadecanoate [17] Tetradecyl heptadecanoate [17] Tetradecyl nonadecanoate [17] Stearyl laurate [18] Stearyl myristate [18] Stearyl palmitate [18] Stearyl stearate [18] Stearyl arcihidate [18]
32.35 18.75 50.78
205.65 170.05 202.17
54.88
205.11
57.36
207.07
38.05 41.60 48.03 49.58 52.84 40.01 45.43 46.68 50.19 42.21 48.86 57.34 59.22 64.96
207.90 210.43 213.85 221.80 201.34 207.89 214.81 217.19 203.23 201.03 203.53 219.74 214.93 226.12
Acknowledgements The author would like to thank Gaziosmanpaşa University Polymer Research Laboratory for the materials and facilities. Appendix A. Supplementary data Fig. 10. FT-IR spectra of DTS and DOS before and after 1000 accelerated thermal cycling.
Supplementary data to this article can be found online at https:// doi.org/10.1016/j.solmat.2019.110006.
Table 4 Thermal energy storage characteristics of DTS and DOS before and after thermal cycling. Materials
Melting temperature (°C)
Melting enthalpy (Jg−1)
Freezing temperature (°C)
Freezing enthalpy (Jg−1)
DTS DOS DTS ATC DOS ATC
47 64 48 63
202.4 194.9 209.4 206.3
46 63 48 63
197.5 191.7 202.0 194.8
References [1] N. Zhang, Y. Yuan, X. Cao, Y. Du, Z. Zhang, Y. Gui, Latent heat thermal energy storage systems with solid–liquid phase change materials: a review, Adv. Eng. Mater. 20 (6) (2018) 1–30. [2] M.H. Abokersh, M. Osman, O. El‐Baz, M. El‐Morsi, O. Sharaf, Review of the phase change material (PCM) usage for solar domestic water heating systems (SDWHS), Int. Energy Storage 42 (2) (2018) 329–357. [3] X. Huang, G. Alva, Y. Jia, G. Fang, Morphological characterization and applications of phase change materials in thermal energy storage: a review, Renew. Sustain. Energy Rev. 72 (2017) 128–145. [4] H. Akeiber, P. Nejat, M.Z.A. Majid, M.A. Wahid, F. Jomehzadeh, I.Z. Famileh, J.K. Calautit, B.R. Hughes, S.A. Zaki, A review on phase change material (PCM) for sustainable passive cooling in building envelopes, Renew. Sustain. Energy Rev. 60 (2016) 1470–1479. [5] B. Xu, P. Li, C. Chan, Application of phase change materials for thermal energy storage in concentrated solar thermal power plants: a review to recent developments, Appl. Energy 160 (2015) 286–307. [6] S.E. Kalnæsa, B.P. Jelle, Phase change materials and products for building applications: a state-of-the-art review and future research opportunities, Energy Build. 94 (2015) 150–176. [7] A. Biçer, A. Sarı, Synthesis and thermal energy storage properties of xylitol pentastearate and xylitol pentapalmitate as novel solid-liquid PCMs, Sol. Energy Mater. Sol. Cells 102 (2012) 125–130. [8] A.A. Aydın, Diesters of high-chain dicarboxylic acids with 1-tetradecanol as novel organic phase change materials for thermal energy storage, Sol. Energy Mater. Sol. Cells 104 (2012) 102–108. [9] H. Mehling, L.F. Cabeza, Heat and Cold StorageWith PCM:an up to Date Introduction into Basics and Applications, Springer, Berlin, Germany, 2008. [10] A. Sharma, V.V. Tyagi, C.R. Chen, D. Buddhi, Review on thermal energy storage with phase change materials and applications, Renew. Sustain. Energy Rev. 13 (2009) 318–345. [11] R. Baetens, B.P. Jelle, A. Gustavse, Phase change materials for building applications: a state-of-the-art review, Energy Build. 42 (9) (2010) 1361–1368. [12] D. Zhou, C.Y. Zhao, Y. Tian, Review on thermal energy storage with phase change materials (PCMs) in building applications, Appl. Energy 92 (2012) 593–605. [13] M. Mazman, L.F. Cabeza, H. Mehling, M. Nogues, H. Evliya, H.Ö. Paksoy, Utilization of phase change materials in solar domestic hot water systems, Renew. Energy 34 (2009) 1639–1643.
DOS can be used as novel PCMs due to their suitable phase change temperatures, LHTES capacity for thermal energy storage applications and structural and thermal consistency upon thermal cycling. Besides DTS and DOS were found stable up to extreme temperatures compared to ambient according to the TGA measurements. Latent heat energy storage capacity of DTS and DOS were found slightly lower than pristine fatty alcohols. DTS and DOS had phase change temperatures of 47 °C and 64 °C for melting respectively and 46 °C and 63 °C for solidification respectively. These phase transition temperatures are suitable for solar thermal applications. The enthalpy values are of 14% less than the precursor for DTS as it is of 23% less for DOS. It was attributed to distorted crystallinity in the structure due to succinate group. It is traditional to ester materials produced from fatty acids or alcohols. DTS and DOS are odorless, noncorrosive and stable. They had also considerable thermal storage capacity. And therefore they are better alternatives to fatty acids and fatty alcohols as solar thermal storage materials.
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D. Kahraman Döğüşcü [14] Z. Zhou, Z. Zhang, J. Zuo, K. Huang, L. Zhang, Phase change materials for solar thermal energy storage in residential buildings in cold climate, Renew. Sustain. Energy Rev. 48 (2015) 692–703. [15] F. Baykut, A. Aydın, The synthesis and physical properties of the homologous series of fatty acids' esters, Reveu De La Faculte Des Sciences De L’Universite D’Istanbul Serie C 34 (1969) 119–148. [16] A.A. Aydın, H. Okutan, High-chain fatty acid esters of myristyl alcohol with even carbon number: novel organic phase change materials for thermal energy storage-1, Sol. Energy Mater. Sol. Cells 95 (2011) 2752–2762. [17] A.A. Aydın, H. Okutan, High-chain fatty acid esters of myristyl alcohol with even carbon number: novel organic phase change materials for thermal energy storage-2, Sol. Energy Mater. Sol. Cells 95 (2011) 2417–2423. [18] A.A. Aydın, High-chain fatty acid esters of 1-octadecanol as novel organic phase change materials and mathematical correlations for estimating the thermal properties of higher fatty acid esters' homologous series, Sol. Energy Mater. Sol. Cells 113 (2013) 44–51. [19] S. Wi, J. Seo, S.G. Jeong, S.J. Chang, Y. Kang, S. Kim, Thermal properties of shapestabilized phase change materials using fatty acid ester and exfoliated graphite
[20] [21] [22] [23] [24]
8
nanoplatelets for saving energy in buildings, Sol. Energy Mater. Sol. Cells 143 (2015) 168–1731. S. Cabus, K. Bogaerts, J.V. Mechelen, M. Smet, B. Goderis, Monotropic polymorphism in ester-based phase change materials from fatty acids and 1,4-butanediol, Cryst. Growth Des. 13 (8) (2013) 3438–3446. A. Sarı, A. Biçer, Ö. Lafcı, M. Ceylan, Galactitol hexa stearate and galactitol hexa palmitate as novel solid-liquid phase change materials for thermal energy storage, Sol. Energy 85 (2011) 2061–2071. A. Sarı, A. Biçer, Thermal energy storage properties and thermal reliability of some fatty acid esters/building material compositesas novel form-stable PCMs, Sol. Energy Mater. Sol. Cells 101 (2012) 114–122. A. Sari, R. Eroglu, A. Biçer, A. Karaipekli, Synthesis and thermal energy storage properties of erythritol tetrastearate and erythritol tetrapalmitate, Chem. Eng. Technol. 34 (1) (2011) 87–92. A. Karaipekli, A. Sarı, Preparation and characterization of fatty acid ester/building material composites for thermal energy storage in buildings, Energy Build. 43 (2011) 1952–1959.