報告書番号

M14004

タイトル（和文）

無着霜ヒートポンプ給湯システムに関する研究開発-第2報：吸着剤塗布熱交の熱・物質移動特性の把握及びシステムの試設計

タイトル（英文）

Study on frost-free heat pump water heater system - 2nd Experimental Study of heat and mass transfer characteristics of desiccant-coated heat exchanger and testing design of the system

概要 （図表や脚注は「報告書全文」に掲載しております）

空気熱源ヒートポンプの室外機（蒸発器）着霜問題に対して、当所は、吸着剤塗布熱交換器（DCHE：Desiccant Coated Heat Exchanger）を用いた無着霜ヒートポンプ給湯システムを考案した。前報のサイクルシミュレーションの結果、従来システムと比べ、1～2割程度の効率向上が見られた。本研究は、現状入手可能なDCHEの熱・物質移動特性を把握し、これを利用した無着霜ヒートポンプ給湯システムの試設計を行った。2℃、80RH％の外気条件において、無着霜運転時間が24minであり、さらに、外気温度が低いほど絶対湿度が小さくなり、処理できる空気の総量が増えるため無着霜運転時間は長くなることが分かった。2℃、80RH％の外気条件において、加熱能力4.5kWのヒートポンプユニットの外寸は700(高)×1000(幅)×(300)(奥行) mm程度であり、現状エコキュートと同等サイズになることが分かった。無着霜運転時間と脱着消費熱量の実験結果を基に、ヒートポンプのエネルギー消費効率（サイクルCOP：給湯加熱量⁄圧縮機投入電力量）を試算した。前報のシミュレーション結果と比べ、7～14％程度低い結果が得られた。無着霜運転時間の延長や、DCHEの塗布フィンの延長、吸着剤の改良などにより、サイクルCOPは前報のシミュレーション結果を上回ることが可能である。

概要 （英文）

In order to resolve the problem of evaporator frosting in air source heat pump water heater systems, we have proposed a frost-free heat pump water heater system with integrated desiccant-coated heat exchanger (DCHE), in which frosting can be retarded by dehumidifying air before entering the evaporator of heat pump. The cycle simulation was carried and the coefficient of the performance (COP) of the proposed system was 10-20% higher than that of the conventional heat pump water heater (eco-cute). In this study, experiments were carried out to access the possibility of the proposed system according to the frost-free operation time, COP and the dimensions of the heat pump unit. The results show that the frost-free operation time is 24 minutes under ambient air conditions of 2C and 80RH%, which is 40% shorter than the frosting operation time of eco-cutes. It is predicated that the frost-free time of the proposed system can be extended, and be equal to the frosting operation time of eco-cutes if the adsorption temperature of the DCHE is raised. Furthermore, it is proved that the desiccant of AQSOA-Z05 used in this experiment can be regenerated under condensing temperatures of heat pumps, such as 50-60C. Design calculation is conducted to determine the physical characteristics of the DCHE and the evaporator, the layout and dimensions of the heat pump unit. The results show that the heat pump unit of the proposed system at the dimensions of 700 (Height) x 1000 (Width) x 300 (Depth) mm, has the water heating capacity of 4.5kW under ambient air conditions of 2C and 80RH%. Compared to the eco-cutes on the market, the dimensions of the heat pump unit of the proposed system is almost the same. Based on the experimental results of the frost-free time and desorption temperature and desorption heat load, the COP of the proposed system is obtained, which is 7-14% lower than that of the simulation result. Here, the COP of the proposed system could be raised to that of the simulation result by extending the frost-free time, saving energy for the desiccant desorption or optimizing the configuration of the DCHE.

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