- 學位論文
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 System
摘要
過去的噴射式製冷系統單獨運轉時的性能普遍不佳，而且大部分的研究皆使用電熱加熱方式來驅動噴射式製冷系統，就連蒸發器等元件所需的熱負載也由電熱提供，如此的設計，額外的能源消耗就比噴射器所產生的製冷效果還要大上許多，並沒有實用的價值；再者，過去的研究為了將噴射式製冷系統的性能發揮，都未考慮到噴射式製冷系統的週邊設備的耗電，如:冷卻水塔，然而這些週邊設備的耗電往往也是不可小覷的。 因此本研究整合了太陽能集熱系統、噴射式製冷系統與變頻空調系統，成功利用串、並聯型並用的設計結合噴射式製冷系統與變頻空調系統，開發出一套串、並聯型太陽能輔助噴射式製冷系統，一方面使用並聯型蒸發器將太陽能轉換為冷氣輔助冷房製冷，減少變頻空調負荷，大幅降低其耗電量，另一方面利用串聯型結合模式過冷卻變頻空調冷凝完的冷媒，降低變頻空調冷凝溫度，提高變頻空調性能。 太陽能輔助噴射式製冷系統的週邊設備中耗能最多的兩個設備為太陽能集熱系統循環泵浦以及冷卻水塔風扇，前人已經將太陽能集熱系統循環泵浦藉由最佳效率點追蹤有效降低循環泵浦的耗電量，因此本研究再透過改善冷卻水塔流道以及提高水泵浦流量，利用步階減速控制(Step-down control)在不影響太陽能輔助噴射式製冷系統的情況下降低風扇轉速，減少風扇耗能。測試結果顯示可較風扇全速運轉降低81~84%的耗能。 本研究建立一套中央監控系統監測太陽能輔助噴射式製冷系統運轉時的溫度、壓力、冷媒質量流率以及系統耗電量，藉由熱力學原理分析比較系統運轉的性能。測試結果顯示變頻空調單獨運轉時的性能係數(COP)約在2.0~2.63之間，當開啟噴射式製冷系統後，太陽能輔助噴射式製冷系統的性能係數提升至4.46~5.54之間，提升46~58%。並且在環境溫度高達36.9℃的測試條件下，整體性能係數仍然能夠達到4.79，大幅提升系統的性能。而噴射式製冷系統的運轉性能係數也能維持0.36~0.44，與性能預測結果相去不遠，表示噴射式製冷系統能夠完全發揮其製冷量，成功與變頻空調結合。
並列摘要
The performance of conventional ejector cooling system (ECS) was poor and the design of ECS using auxiliary heater to generate ECS or using heater as the heat load for evaporator wasted more energy than the cooling effect of ECS. Furthermore, in order to maintain the best performance, the past studies did not consider the power consumption of peripherals, which cannot be underestimated. Solar-assisted ejector cooling system (SACH-k2) combines solar heating system, ECS and inverter-type air-conditioner (IAC) and is developed in the present study. In SACH-K2, ECS is connected with IAC in series and parallel configuration. In parallel, ECS is driven by solar heat to provide partial cooling load to reduce the power consumption of the IAC. In series, the cooling effect of ECS generated by solar heat is used to cool the condenser of IAC to increase its COP and reduce the power consumption of the compressor. The power consumption of peripheral device in SACH-k2 is too high to commercialization. The solar collector pump and cooling tower fan waste too much energy while SACH-K2 is operating. The power consumption of solar collector pump is reduced by using MPPT control. This study focuses on cooling tower fan to improve the design of cooling tower and use Step-down control to reduce the power consumption of cooling tower fan under the premise that ejector cooling system operates stably. The experiment result shows that cooling tower fan could save 81%~84% power consumption compared to full speed running fan. This study builds up a central control system measure the temperature, pressure, refrigerant flow rate and power consumption of ECS and IAC and analyzes the performance. According to the analysis of experiment results, the performance coefficient (COP) when IAC operates alone is between 2~2.63 and the COP is 4.46~5.54 raised 46~58% after ECS combines with IAC. What is more, the COP is 4.79 under the ambient temperature 36.9℃. The performance coefficient of ECS (COPECS) is between 0.36~0.44 which is match with simulation in ejector performance predicted.