太陽能輔助噴射式製冷系統性能提升研究

Study of Performance Improvement on Solar-Assisted Ejector Cooling/Heating System

顏昭文(Chao-Wen Yen)

指導教授 ： 黃秉鈞

國立臺灣大學/工學院/機械工程學研究所/博士(2010年)

https://doi.org/10.6342/NTU.2010.02689

摘要

傳統的熱驅動式製冷系統，如噴射式、吸附式與吸收式等，在熱源不穩定時，為提供穩定的空調製冷能力，往往會加裝加熱器方式以彌補熱能的不足，因而造成成本提高與不便。
本研究提出的太陽能輔助噴射式製冷系統，係結合太陽能集熱系統、噴射式製冷系統與變頻空調系統。並聯型太陽能輔助噴射式製冷系統SACH-2係以並聯方式連接噴射式製冷系統與變頻空調系統，主要讓噴射式太陽製冷系統輔助變頻空調系統來達成節電目的。另一串聯型太陽能輔助噴射式製冷系統SACH-1係以串聯方式連接無動件噴射式製冷系統與變頻空調系統，主要是以太陽能輔助無動件噴射式製冷系統來降低變頻空調系統冷凝溫度，提升變頻空調系統的運轉性能來節電。
針對SACH-2，本研究成功開發噴射式製冷系統的膨脹閥回饋控制系統，在噴射器的吸入端（蒸發器入口）安裝一電子式膨脹閥，以回饋控制調整膨脹閥的開度去控制蒸發器溫度，使噴射器即使在不穩定的熱源下也能操作在臨界雙阻塞模態或非臨界雙阻塞模態，使噴射器發揮最佳效能，並且當偵測到噴射器即將發生逆流時，回饋控制系統會將膨脹閥關閉，避免蒸發器由製冷變成製熱，反而增加冷房負載。系統運轉測試結果顯示太陽能驅動的噴射式製冷系統能讓變頻空調系可以在太陽能變化下經常運作，最大節省電量為63％。在系統長期運轉方面，已連續運轉8個多月的SACH-2，與單獨變頻空調系統運轉比較，節電量在30-80％，平均節電量為51％。
針對SACH-1，本研究成功運轉新開發的混合冷媒於無動件噴射式系統。混合冷媒於蒸發溫度10℃時，潛熱為410.69kJ/kg，約為R365mfc的兩倍，因此在同樣抽吸流下混合冷媒會有2倍的製冷量。混合冷媒密度較小，可減少充填量25％，成本減少47％。噴射器的等截面擴散段抽吸口採雙錐形設計，噴射器面積比為8.45。SACH-1系統以電熱運轉測試的變頻空調系統節電量約為41.8%，太陽能運轉時可節省電量57.8%。
總結本論文的研究結果，太陽能輔助製冷系統證明可改善傳統的熱驅動式製冷系統缺失，解決隨天氣變化太陽能操作的自動控制問題，以及首度成功利用混合冷媒均成功與太陽熱能連結運轉達成節電目的，對於商業化及應用上有顯著的貢獻。

關鍵字

太陽能 ； 噴射式系統 ； 噴射式製冷 ； 太陽能製冷

並列摘要

The conventional heat power cooling systems like ejector system, adsorption system and absorption system use auxiliary heater to provide steady cooling effect, while the thermal energy is unstable. It is very unsuitable to consume a lot of cost; therefore, solar-assisted ejector cooling/heating system (SACH) was developed in this study for improving the defects of conventional heat power cooling system.
SACH combines solar heating system, ejector cooling system and inverter-type air conditioner. SACH-2 connects ejector cooling system and inverter-type air conditioner in parallel, which saves electricity by assist of solar ejector cooling system. SACH-1 connects pump-less ejector cooling system and inverter-type air conditioner in series, which uses pump-less ejector cooling system to lower condensing temperature of inverter-type air conditioner and improve inverter-type air conditioner operating performance.
On SACH-2, expansion valve feedback system in ejector cooling system is developed. Electronic expansion valve which adjusts opening of expansion valve to control evaporating temperature by feedback control is set up in suction side of ejector (evaporator inlet). Even with unstable heat, ejector can operate in double-chocking critical mode and none double-chocking critical mode to have an optimum performance. When a backflow is about to happen in the ejector, the feedback control system will turn off the expansion valve, avoiding transforming evaporator from cooling to heating, which increasing cooling load. Performance result shows that the ejector cooling system driving by solar energy works normally even with a variation on irradiation, while the maximum power saving is 63%. On long-term performance, SACH-2 has operated continuously over 8 months and has 30%-80% at power saving and also 51% at total power saving, compared with operating inverter-type air conditioner alone.
On SACH-1, new type of mixing refrigerant is built in pump-less ejector cooling system. The mixing refrigerant has a latent heat at 410.69kJ/kg twice as much as R365mfc while the temperature is at 10 degree Celsius; therefore, the mixing refrigerant has a double cooling capacity with the same suction flow. The mixing refrigerant has a lower density means reducing 25% filling capacity and 47% cost. The constant cross-section diffusion part is designed in double-conical, and the ratio of area is 8.45. SACH-1 has a power saving at 41.8% operated by electric heating and a power saving at 57.8% operated by solar energy.
In conclusion, solar-assisted ejector cooling/heating system improves the disadvantage of conventional thermal-energy assisted cooling system, solves the problem of automatic control with a solar-energy variation, and for the first time mixing refrigerant is successful connected with solar energy to save power. It makes a eminent contribution in commerce and on application.

並列關鍵字

solar energy ； ejector system ； ejector cooling ； solar cooling

參考文獻

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