Korean Chemical Engineering Research

The Korean Institute of Chemical Engineers (한국화학공학회)
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Thermoelectric Efficiency Improvement in Vacuum Tubes of Decomposing Liquid Lithium-Ammonia Solutions

진공튜브 속에서 분해하는 리튬암모니아 솔루션의 열전효율 향상

  • Lee, Jungyoon (Department of Information & Communications Engineering, Dongguk University) ;
  • Kim, Miae (Department of Energy and Advanced Material Engineering, Dongguk University) ;
  • Shim, Kyuchol (Department of Energy and Advanced Material Engineering, Dongguk University) ;
  • Kim, Jibeom (Department of Energy and Advanced Material Engineering, Dongguk University) ;
  • Jeon, Joonhyeon (Department of Information & Communications Engineering, Dongguk University)
  • 이정윤 (동국대학교 정보통신공학과) ;
  • 김미애 (동국대학교 융합에너지 신소재공학과) ;
  • 심규철 (동국대학교 융합에너지 신소재공학과) ;
  • 김지범 (동국대학교 융합에너지 신소재공학과) ;
  • 전준현 (동국대학교 정보통신공학과)
  • Received : 2012.11.27
  • Accepted : 2013.03.07
  • Published : 2013.06.01
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Abstract

Lithium-ammonia (Li-$NH_3$) solutions are possible to be successfully made under the vacuum condition but there still remains a problem of undergoing stable and reliable decomposition in vacuum for high-efficiency thermoelectric power generation. This paper describes a new method for improving the thermoelectric conversion efficiency of Li-$NH_3$ solutions in vacuum. The proposed method uses a 'U'-shaped Pyrex vacuum tube for the preparation and decomposition of pure fluid Li-$NH_3$ solutions. The tube is shaped so that a gas passageway ('U') connecting both legs of the 'U' helps to balance pressure inside both ends of the tube (due to $NH_3$ gasification) during decomposition on the hot side. Thermoelectric experimental results show that solution reaction in the 'U'-shaped tube proceeds more stably and efficiently than in the 'U'-shaped tube, and consequently, thermoelectric conversion efficiency is improved. It is also proved that the proposed method can provide a reversible reaction, which can rotate between synthesis and decomposition in the tube, for deriving the long-time, high-efficiency thermoelectric power.

순수한 리튬-암모니아(Li-$NH_3$) 솔루션의 생성은 진공 상태에서 가능하지만, 고효율 열전전력을 얻기 위한 안정적이고 신뢰성 있는 분해에 대한 문제가 아직 남아있다. 본 논문은 Li-$NH_3$ 솔루션의 열전변환 효율을 향상시키기 위한 새로운 방법을 다루었다. 제안된 방법은 Li-$NH_3$ 솔루션의 합성과 분해를 위해 'U' 형태의 파이렉스 진공 튜브를 사용하였다. 튜브 상부에는 기존 'U' 형태의 파이렉스 진공 튜브의 두 다리를 연결하는 기체의 이동통로가 있는데, 이는 고온부(Hot side)에서 분해가 진행될 때 $NH_3$ 기화에 따른 양단의 내부압력 불균형을 방지하는 역할을 한다. 열전 실험결과, 'U' 형태 튜브 속에서 솔루션 반응은 기존 'U' 형태에 비해 매우 안정적이고 효율적으로 이루어졌으며, 결과적으로 열전변환 효율이 향상됨을 보였다. 또한, 제안 방식은 장시간에 걸친 고효율 열전 발전을 위해 튜브 속에서 합성과 분해가 순환되는 가역반응을 제공함이 입증되었다.

Keywords

References

  1. Hayama, S., Skipper, N. T., Wasse, J. C. and Thompson, H., "X-ray Diffraction Studies of Solutions of Lithium in Ammonia: The Structure of the Metal-nonmetal Transition," J. Chem. Phys., 116, 2991-2996(2002). https://doi.org/10.1063/1.1436120
  2. Wasse, J. C., Hayama, S., Masmanidis, S., Stebbings, S. L. and Skipper, N. T., "The Structure of Lithium-ammonia and Sodiumammonia Solutions by Neutron Diffraction," J. Chem. Phys., 118, 7486-7494(2003). https://doi.org/10.1063/1.1563594
  3. Salter, T. E., Mikhailov, V. A., Evans, C. J. and Ellis, A. M., "Infrared Spectroscopy of $Li(NH_{3})_{n}$ Clusters for n=4-7," J. Chem. Phys., 125, 034302(1-10)(2006). https://doi.org/10.1063/1.2208349
  4. Salter, T. E. and Ellis, A. M. "Structures of Small $Li(NH_{3})_{n}$ and $Li(NH_{3})_{n}^{+}$ Clusters (n=1-5): Evidence from Combined Photoionization Efficiency Measurements and ab Initio Calculations," J. Phys. Chem. A, 111, 4922-4926(2007). https://doi.org/10.1021/jp071622a
  5. Chuev, G. N., Quémerais, P. and Crain, J., "Nature of the Metalnonmetal Transition in Metal-ammonia Solutions. I. Solvated Electrons at Low Metal Concentrations," J. Chem. Phys., 127, 244501(1-16)(2007). https://doi.org/10.1063/1.2812244
  6. Lee, J. M. and Jhon, M. S., "Application of Liquid Theory to Sodium-Ammonia Solution," Bull. Kor. Chem. Soc., 2, 90-96(1981).
  7. Schulz, C. P., Gerber, A., Nitsch, C. and Hertel, I. V., "Spectroscopy of free Sodium-ammonia Clusters," Z. Phys. D., 20, 65-67(1991). https://doi.org/10.1007/BF01543939
  8. Almeida, T. S. and Cabral, B. J. C., "Ab Initio Approach to the Electronic Properties of Sodium-ammonia Clusters: Comparison with Ammonia Clusters," J. Chem. Phys., 132, 094307(1-10)(2010). https://doi.org/10.1063/1.3329371
  9. Dewald, J. F. and Lepoutre, G., "The Thermoelectric Properties of Metal-Ammonia Solutions. I. The Thermoelectric Power of Sodium and Potassium at $-33^{\circ}$," J. Am. Chem. Soc., 76, 3369-3373 (1954). https://doi.org/10.1021/ja01642a005
  10. Arendt, P., "Dissipationless Electric Current Flow Through Decomposing Liquid Metal-ammonia Solutions Between Copper Electrodes," Electrochim. Acta, 30, 709-718(1985). https://doi.org/10.1016/0013-4686(85)80117-1
  11. Arendt, P., "Circulating Currents in Tubes of Decomposing Liquid Lithium-ammonia Solutions in the High-conducting State," Electrochim. Acta, 31, 445-449(1986). https://doi.org/10.1016/0013-4686(86)80107-4
  12. Arendt, P., "The Xerogel Made from Decomposing Liquid Metal-ammonia Solutions-A Solid Material Which Carries Current Densities of $10^{5}$ A $cm^{2}$ at Room Temperature," J. Phys. Chem. Solids, 49, 511-517(1988). https://doi.org/10.1016/0022-3697(88)90062-5
  13. Arendt, P., "Change in Electrical Conductivity of a Gel Made From Decomposing Liquid Metal-ammonia Solutions as the Gel Is Dried to a Xerogel," Solid State Commun., 74, 559-565 (1990). https://doi.org/10.1016/0038-1098(90)90676-3
  14. Jeon, J. and Kim, J., "Thermoelectric Experiment of a Fluid Lithium-Ammonia Solution in a U-Shaped Pyrex Tube with Highly Pure Vacuum State," Adv. Sci. Lett., 8, 550-554(2012). https://doi.org/10.1166/asl.2012.2440
  15. Park, H. Kim, J. and Jeon, J., "Experimental Study of Thermoelectric Material Using Lithium-Ammonia $(Li(NH_{3})_{n})$ Solution," Korean Chem. Eng. Res.(HWAHAK KONGHAK), 49, 263-270(2011). https://doi.org/10.9713/kcer.2011.49.2.263
  16. Yurtseven, H. and Caglar, O., "A Linear Variation of the Thermal Expansivity with the Isothermal Compressibility for Ammonia Solid III Near the Melting Point," Korean J. Chem. Eng., 27, 249-252(2010). https://doi.org/10.2478/s11814-009-0335-z