Electrical energy conversion of the low-temperature exhaust heat by CO2 hydrate heat cycle

2022 Fiscal Year Final Research Report

• Project/Area Number: 20H02675
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 31020:Earth resource engineering, Energy sciences-related
• Research Institution: Kitami Institute of Technology
• Principal Investigator: Obara Shin'ya 北見工業大学, 工学部, 教授 (10342437)
• Co-Investigator(Kenkyū-buntansha): 村田 美樹 北見工業大学, 工学部, 教授 (40271754)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: ガスハイドレート / 蓄電池 / 物理電池 / 低温廃熱 / 小温度差発電 / 未利用エネルギー / 再生可能エネルギー / 廃熱回収

Outline of Final Research Achievements

(1) The losses in the gas hydrate production process and in the expander by the proposed system could be improved, reducing the efficiency of the gas hydrate production process by 9% and the losses in the expander by 9%. As a result, the energy flow was as shown in Fig. 6 and the electricity output could be increased from 9.2% to 18.7%.
(2) The formation and dissociation of gas hydrates were investigated on the basis of test data on the structure of heat and mass transfer at the three-phase interface (water (liquid), CO2 (gas), hydrate (solid), heat transfer surface (solid) and carbon fibre supported catalyst (solid)) on the heat transfer surface of a heat exchanger.
In addition to (1) and (2) above, from the optimisation of the temperature and pressure conditions during the formation and dissociation of gas hydrates, a system with an overall efficiency of 54% could be developed.

Free Research Field

熱工学、電力工学

Academic Significance and Societal Importance of the Research Achievements

国内の1次エネルギー消費量のおよそ7割が、低温排熱（概ね200℃以下）として最終的に放出されている。この低温排熱を動力や電力に変換できたなら、温室効果ガス排出の大幅な抑制となる。本研究では高温側の熱源として上で述べた低温排熱、低温側の熱源として外気を用いて、これら2つの熱源の温度差から実用的な効率で電力を得られるかが社会的意義である。