Fundamental research of CO2 heat pump assisted with geothermal energy for heating system in greenhouse

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K05895
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 41040:Agricultural environmental engineering and agricultural information engineering-related
• Research Institution: Hirosaki University
• Principal Investigator: Moritani Shigeoki 弘前大学, 農学生命科学部, 准教授 (30539870)
• Co-Investigator(Kenkyū-buntansha): 石山 新太郎 弘前大学, 理工学研究科, 教授 (60355021)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: ビニールハウス加温 / 地中熱ヒートポンプ

Outline of Final Research Achievements

Ground-source heat pumps (GSHPs) have been used to chill water to
facilitate cooling of strawberry grown within containers during the summer. Two types of soil containers and cooling systems have been considered. The cooling efficiency of each system was evaluated by calculating the coefficient of performance (COP) from observed temperatures. Simple equipment for measuring COP requires a basic thermodynamics approach and many coefficients of the gas state equation and saturated liquid line equation are affected by factors such as pressure, temperature, and volume. The coefficients used in these equations vary depending on the literature. In this study, the influence of a change in the coefficients on the precision of the COP calculation was examined.

Free Research Field

地域環境工学

Academic Significance and Societal Importance of the Research Achievements

ヒートポンプの農業利用において、冷媒熱力学を考慮したCOP計算を行った例は少なく、より理論的なCOPシミュレーションが期待できる。同時に冷媒COP計算に用いる係数は、実験結果を基にして得られており、文献毎に異なる値を示している。また、有効数字10桁におよぶ場合もあり、農業利用においてどこまで厳密な値を採用したらいいのかといった知見が少ない。本研究の結果から、実用的なCOP計算について検討することができた。