Scholarly article on topic 'Thermal Reliability of Myristic Acid/Palmitic Acid/Sodium Laurate Eutectic Mixture: A Feasibility Study of Accelerated Aging for Thermal Energy Storage Application'

Thermal Reliability of Myristic Acid/Palmitic Acid/Sodium Laurate Eutectic Mixture: A Feasibility Study of Accelerated Aging for Thermal Energy Storage Application Academic research paper on "Materials engineering"

CC BY-NC-ND
0
0
Share paper
Academic journal
Energy Procedia
OECD Field of science
Keywords
{"Thermal reliability" / "phase change material" / "thermal properties"}

Abstract of research paper on Materials engineering, author of scientific article — Hadi Fauzi, Hendrik S.C. Metselaar, T.M.I. Mahlia, Mahyar Silakhori

Abstract The thermal characteristic stability of myristic acid/palmitic acid/sodium laurate (MA/PA/SL) eutectic mixtures have been measured by a thermal cycling test. The phase change temperature and heat storage capacity of each eutectic were evaluated by differential scanning calorimetric (DSC) after 300, 700, and 1000 thermal cycles. The thermal properties of the MA/PA/SL eutectic mixture shows only a minor changes on melting temperature (Tm) and latent heat of fusion (ΔHf) after 300, 700, and 1000 thermal cycles. The chemical structure of MA/PA/SL shows no degradation after 1000 melting/cooling cycles as well as MA/PA/SL has a better thermal performance during heating and cooling process. Therefore, it is noted that the MA/PA/SL eutectic mixture is applicable for long term use as a phase change material in thermal energy storage (TES) applications.

Academic research paper on topic "Thermal Reliability of Myristic Acid/Palmitic Acid/Sodium Laurate Eutectic Mixture: A Feasibility Study of Accelerated Aging for Thermal Energy Storage Application"

CrossMark

Available online at www.sciencedirect.com

ScienceDirect

Energy Procedia 61 (2014) 49 - 54

The 6th International Conference on Applied Energy - ICAE2014

Thermal reliability of myristic acid/palmitic acid/sodium laurate eutectic mixture: a feasibility study of accelerated aging for thermal energy storage application

Hadi Fauzia, c , Hendrik S. C. Metselaar a,*, T.M.I. Mahliab, Mahyar Silakhoria

aDepartment of Mechanical Engineering, University of Malaya, Kuala Lumpur 50603, Malaysia bDepartment of Mechanical Engineering, University Tenaga Nasional, Kajang 43000, Selangor, Malaysia _cDepartment of Chemical Engineering, Syiah Kuala University, Banda Aceh 23111, Indonesia_

Abstract

The thermal characteristic stability of myristic acid/palmitic acid/sodium laurate (MA/PA/SL) eutectic mixtures have been measured by a thermal cycling test. The phase change temperature and heat storage capacity of each eutectic were evaluated by differential scanning calorimetric (DSC) after 300, 700, and 1000 thermal cycles. The thermal properties of the MA/PA/SL eutectic mixture shows only a minor changes on melting temperature (Tm) and latent heat of fusion (AHf) after 300, 700, and 1000 thermal cycles. The chemical structure of MA/PA/SL shows no degradation after 1000 melting/cooling cycles as well as MA/PA/SL has a better thermal performance during heating and cooling process. Therefore, it is noted that the MA/PA/SL eutectic mixture is applicable for long term use as a phase change material in thermal energy storage (TES) applications.

© 2014 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license

(http://creativecommons.Org/licenses/by-nc-nd/3.0/).

Peer-review under responsibility of the Organizing Committee of ICAE2014

Keywords: Thermal reliability, phase change material, thermal properties

1. Introduction

Much research has been done to determine the thermal characteristics of latent heat thermal energy storage materials [1-5]. Latent heat thermal energy storage materials or Phase Change Materials (PCMs) are commonly divided in two categories which are organic and inorganic. Organic PCMs have advantages over inorganic PCMs due to chemical and thermal stability, low undercooling, and no corrosiveness in compatibility with other materials [2]. Fatty acids are promising organic PCMs as they have a wide suitable phase transition temperature, high latent heat capacity, are non-toxic, have low undercooling, are not corrosive, have low volume change, and good thermal reliability when used for a large number of

1876-6102 © 2014 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license

(http://creativecommons.org/licenses/by-nc-nd/3.0/).

Peer-review under responsibility of the Organizing Committee of ICAE2014

doi:10.1016/j.egypro.2014.11.903

thermal cycles. Besides, fatty acid can be mixed in order to obtain a material with new thermal properties which is called eutectic or poly mixture phase change material [3, 4, 6, 7].

Nomenclature

Tm melting temperature (oC) AHf latent heat of fusion (J g-1) Wt.% weight percentage

* Corresponding author. Tel.: +603-79674451; fax: +603-796744.

E-mail address: h.metselaar@um.edu.my.

A current study on eutectic phase change materials with an added surfactant reported that the surfactant was able to adjust the phase transition temperature and the latent heat capacity of the fatty acid eutectic mixture to a suitable ranges which is compatible with required specification of thermal energy storage (TES) devices [8-10]. The eutectic fatty acid with surfactant addition also has a good thermal reliability after a large number of thermal cycles due to its small change of thermal properties and chemical structure stability [9, 11]. All of those advantage make that fatty acids with surfactant have better properties than other fatty acid eutectics. The thermal reliability of PCM plays an important rule to ensure the long term performance of the PCM for utility life and economic feasibility of latent heat thermal energy storage (LHTES) devices [12].

In this study, we evaluate the thermal reliability, chemical structure stability, and thermal performance stability of myristic acid/palmitic acid/sodium laurate (MA/PA/SL) subjected to 0, 300, 700, and 1000 thermal cycles.

2. Material and methods

The eutectic mixture of myristic acid/palmitic acid/sodium laurate (MA/PA/SL) was prepared by blending a 70 wt.% MA (Acros Organic) with 30 wt.% PA and adding a 10 wt.% of SL (Sigma Aldrich) as surfactant at constant temperature 80oC for 20 minute, this eutectic composition was selected due to its better thermal properties than other compositions [8, 10]. The thermal reliability testing of the MA/PA/SL eutectic mixture was performed using a fabricated thermal cycling test setup described by Fauzi, et al. [11] to evaluate the thermal properties and thermal performance stabilities of MA/PA/SL eutectic mixture subjected to 300, 700, and 1000 melting/cooling cycles. The changes of thermal properties of MA/PA/SL after 300, 700 and 1000 thermal cycles were measured using a Differential Scanning Calorimeter (DSC, Mettler Toledo, DSC1 Star6 system) [8]. While the stability of chemical properties (chemical structure) between un-cycled MA/PA/SL and MA/PA/SL after 1000 melting/cooling cycles was evaluated using a Fourier transform infrared spectroscopy (FT-IR, Bruker IFS 66/S) [11].

3. Results and discussion

3.1. Stability of thermal properties

The DSC charts result of MA/PA/SL subjected to 0, 300, 700, and 1000 thermal cycles are shown in Fig. 1. The melting temperature (Tm) and the latent heat of fusion are obtained from the onset point and numerical integration of area peak under of each curve [13].

The thermal properties of MA/PA/SL are shown in Table 1 and indicate that the melting temperature and latent heat of fusion of MA/PA/SL display irregular changes with an increasing number of thermal cycles.

Table 1. Thermal properties of MA/PA/SL eutectic mixtures subjected to thermal cycling number

Eutectic PCM_Number of thermal cycling Melting temperature, Tm (oC) Latent heat of fusion, AH/ (J. g-1)

0 42.00[10] 174.47[10]

300 46.79 176.79

700 41.83 180.91

1000 40.78 175.34

MA/PA+ 10% SL

The melting temperature of MA/PA/SL shows an increases to 46.79 oC after 300 thermal cycles, furthermore it tends to decrease after 700 and 1000 thermal cycles to below the melting temperature of un-cycled MA/PA/SL. The latent heat of fusion of MA/PA/SL shows a trend to increase after 300 and 700 thermal cycles to 176.79 J.g-1 and 180.91 J.g-1 while after 1000 thermal cycles the latent heat of fusion of MA/PA/SL dropped to 175.34 J.g-1 but still above of latent heat of fusion of un-cycled MA/PA/SL. The changes of thermal properties of fatty acid eutectic mixtures as PCM after a large number of heating/cooling cycles could be caused by changes in the chemical structures of PCM or the increasing amount of impurities contents (2-3, wt.%) in the fatty acids used in preparation of the eutectic PCM [11].

Fig. 1. DSC curve of MA/PA/SL subj ected to a different number of thermal cycles

Referring to the literature [12, 14-18] it can be noted that the change in melting temperature (Tm) and latent heat of fusion (AHf) of MA/PA/SL after 1000 thermal cycles are of an acceptable level for uses as PCM for LHTES applications such as solar space and solar water heating.

3.2. Chemical structure stability

Fig. 2 shows the FT-IR curve of un-cycled MA/PA/SL and MA/PA/SL after 1000 thermal cycles and it can be seen that both spectra have all peaks at the same frequencies. This means that the chemical structure of MA/PA/SL eutectic mixture underwent no degradation after 1000 melting/cooling cycles.

The stability of the chemical structure of MA/PA/SL eutectic mixture obtained in this study confirmed that the changes of thermal properties of MA/PA/SL eutectic mixture subjected to repeated thermal cycles were not caused by degradation of chemical structure these PCM.

Fig. 2. FT-IR curve of un-cycled MA/PA/SL and MA/PA/SL after 1000 thermal cycles

3.3. Thermal performance stability

The thermal performance stability of MA/PA/SL eutectic mixture subjected to heating and cooling processes shown in Figure 3. These results shows the melting and solidification time at the 1 and 1000 thermal cycles of MA/PA/SL eutectic mixture.

Fig. 3.a shows that the endothermic time of MA/PA/SL at 1000 thermal cycles was shorter than MA/PA/SL at 1 thermal cycles in absorbing the heat and reach the melting point of 42 oC [10] which are 4.50 min and 6.67 min, respectively. Furthermore, a different way occur during exothermic process as shown in Fig. 3.b indicated that exothermic time of MA/PA/SL at 1000 thermal cycles was longer than the MA/PA/SL at 1 thermal cycles (4.67 min and 4.33 min) to reach the solidification point of 41.57 oC [10].

These results confirmed that the improvement of thermal conductivity of MA/PA with the addition of SL 10 wt% [10] was bring a good heat transfer characteristic and thermal performance stability to the eutectic PCM.

Fig. 3. Thermal performance stability of MA/PA/SL at 1 and 1000 thermal cycles a) heating process, b) cooling process

4. Conclusions

The thermal reliability of testing MA/PA/SL eutectic mixture was performed to evaluate the thermal and chemical properties stability after 300, 700, and 1000 thermal cycles. It was shown that the thermal properties showed only minor changes with no clear trend up to 1000 thermal cycles. Identification of chemical structures showed that the MA/PA/SL has a good chemical stability after 1000 thermal cycles. Furthermore, the thermal performance of MA/PA/SL also shows a great improvement with increasing the number of thermal cycles. Therefore, it can be concluded that the change of thermal properties, chemical stability and thermal performance stability of tested eutectic PCM in this study was acceptable for application in LHTES systems.

Acknowledgements

The authors acknowledge the Malaysia Ministry of Higher Education and Faculty of Engineering University of Malaya through High Impact Research grant (UM.R/HIR/M0HE/ENG/21-D000021-16001).

References

1. Kaygusuz, K., The Viability of Thermal Energy Storage. Energy Sources, 1999. 21(8): p. 745755.

2. Zalba, B., Marin, J. M., Cabeza, L. F., Mehling, H., Review on thermal energy storage with phase change: materials, heat transfer analysis and applications. Applied Thermal Engineering, 2003. 23(3): p. 251-283.

3. Kaygusuz, K. and A. Sari, Thermal Energy Storage System Using a Technical Grade Paraffin Wax as Latent Heat Energy Storage Material. Energy Sources, 2005. 27(16): p. 1535-1546.

4. Kaygusuz, K. and A. Sari, Thermal Energy Storage Performance of Fatty Acids as a Phase Change Material. Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2006. 28(2): p. 105-116.

5. Farid, M.M., Khudhair, A. M., Razack, S. A. K., Al-Hallaj, S., A review on phase change energy storage: materials and applications. Energy Conversion and Management, 2004. 45(9-10): p. 1597-1615.

6. Feldman, D., Shapiro, M. M, Banu, D., Fuks, C. J., Fatty acids and their mixtures as phase-change materials for thermal energy storage. Solar Energy Materials, 1989. 18(3-4): p. 201216.

7. Mehling, H. and L. Cabeza, Basic thermodynamics of thermal energy storage, in Heat and cold storage with PCM. 2008, Springer Berlin Heidelberg. p. 1-10.

8. Fauzi, H., Metselaar, H. S. C., Mahlia, T. M. I., Silakhori, M., Nur, H., Phase change material: Optimizing the thermal properties and thermal conductivity of myristic acid/palmitic acid eutectic mixture with acid-based surfactants. Applied Thermal Engineering, 2013. 60(1-2): p. 261-265.

9. Matsui, T., Yoshida, M., Yamasaki, H., Hatate, Y., Thermal Properties of Multicomponent Fatty Acids as Solid-Liquid Phase Change Materials for Cooling Applications. Chemical Engineering Communications, 2007. 194(1): p. 129-139.

10. Fauzi, H., Metselaar, H. S. C., Mahlia, T. M. I., Silakhori, M., Sodium laurate enhancements the thermal properties and thermal conductivity of eutectic fatty acid as phase change material (PCM). Solar Energy, 2014. 102(0): p. 333-337.

11. Fauzi, H., Metselaar, H. S. C., Mahlia, T. M. I., Silakhori, M., Thermo-physical stability of fatty acid eutectic mixtures subjected to accelerated aging for thermal energy storage (TES) application. Applied Thermal Engineering, 2014. 66(1-2): p. 328-334.

12. San, A., H. San, and A. Onal, Thermal properties and thermal reliability of eutectic mixtures of some fatty acids as latent heat storage materials. Energy Conversion and Management, 2004. 45(3): p. 365-376.

13. Dodd, J.W., K.H. Tonge, and B.R. Currell, Thermal methods. 1987. Medium: X; Size: Pages: 360.

14. San, A., Thermal reliability test of some fatty acids as PCMs used for solar thermal latent heat storage applications. Energy Conversion and Management, 2003. 44(14): p. 2277-2287.

15. Hasan, A. and A.A. Sayigh, Some fatty acids as phase-change thermal energy storage materials. Renewable Energy, 1994. 4(1): p. 69-76.

16. San, A. and K. Kaygusuz, Some fatty acids used for latent heat storage: thermal stability and corrosion of metals with respect to thermal cycling. Renewable Energy, 2003. 28(6): p. 939-948.

17. Sharma, A., S.D. Sharma, and D. Buddhi, Accelerated thermal cycle test of acetamide, stearic acid and paraffin wax for solar thermal latent heat storage applications. Energy Conversion and Management, 2002. 43(14): p. 1923-1930.

18. Zhang, J.-J., Zhang, J-L., He, S-M., Wu, K-Z., Liu, X-D., Thermal studies on the solid-liquid phase transition in binary systems of fatty acids. Thermochimica Acta, 2001. 369(1-2): p. 157160.