Performance of Thermal Energy Storage Unit Using Solid Ammoniated Salt (CaCl₂-NH₃ System)

Yuki Sakamoto, Hideki Yamamoto

Faculty of Environmental and Urban Engineering, Kansai University, Suita, Japan.
Faculty of Informatics, Naragakuen University, Nara, Japan.

DOI: 10.4236/nr.2014.58031                

Abstract

The exothermic chemical reaction of CaCl₂ (calcium chloride) with NH₃ (ammonia) can be utilized as an energy storage system. Since this reaction is a typical gas-solid reaction, the reaction rate is controlled by the heat transfer rate. In order to improve the low heat transfer rate of the ammoniation and the deammoniation of CaCl₂, the influence of a heat transfer media (Ti: titanium) on the heat transfer rate of the solid ammoniated salt (CaCl₂.mNH₃) was studied and tested experimentally. The performance tests were carried out under the conditions of various weight ratios of Ti. No decrease of the activation of chemical reaction and no corrosion of experimental apparatus were observed on the repeated runs (≥30 times each). The heat transfer rate of ammoniated salt was greatly improved by adding Ti under the constant pressure (0.5 MPa). The reaction time required for the ammoniation of CaCl₂ mixed with Ti was approximately 16% - 54% shorter than that of CaCl₂ alone, and the reaction time required for the deammoniation was also approximately 19% - 59% shorter than that of CaCl₂ alone.

Keywords

Energy Storage Unit, Calcium Chloride (CaCl₂), Ammonia (NH₃), Ammoniated Salt, Ammoniation, Heat Transfer Media

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Yoneda, N. and Hagiwara, S. (1979) Study of Chemical Heat Pump for Thermal Energy Storage. Journal of Solar Energy of Japan, 19, 4-15 (in Japanese).
[2]	Wentworth, W.E. and Jhonston, D.W. (1981) Chemical Heat Pumps Using a Dispersion of a Metal Salt Ammoniate in an Inert Solvent. Solar Energy, 26, 141-146. http://dx.doi.org/10.1016/0038-092X(81)90077-3
[3]	Jeager, F. and Fox, E.C. (1981) Thermal Storage Studies for Solar Heating and Cooling: Application Using Chemical Heat Pumps, US D.O.E Report CS-30248-T-1.
[4]	Wentworth, W.E., Ayala, J.A. and Alcala, R. (1982) Effect of Solvent on CaCl2-NH3 Equilibria in Suspensions. The Journal of Physical Chemistry, 86, 3484-3489.
[5]	Sakamoto, Y., Yamamoto, H., Sanga, S. and Tokunaga, J. (1990) Performance of Thermal Storage Unit Using CaCl2-NH3 System Mixed with Ti. The Canadian Journal of Chemical Engineering, 68, 948-951. http://dx.doi.org/10.1002/cjce.5450680609
[6]	Sakamoto, Y. (2008) Measurement of Thermophysical Properties of Thermal Storage System—Measurement of CaCl2.nNH3 system by Arbitrary Heating Method. Study Reports of Narabunka Women’s College, 39, 39-48.
[7]	Sakamoto, Y. (2011) Measurement of Thermophysical Properties of Thermal Storage System—Effect of Heat Transfer Media. The Bulletin of Nara Sangyo University, 27, 61-66.
[8]	Buehn, J., Hudspeth, A. and Villanueva, G. (2011) Solar Ammonia Absorption Refrigerator Senior Design Project. Saint Martin’s University, Lacey, Washington. http://www.solaripedia.com/files/1113.pdf