- 學位論文
氨水型吸收式冷凍系統之性能研究
An Experimental Study of the Performance on Aqua-Ammonia Absorption Refrigeration System
摘要
吸收式冷凍系統具備經濟、環保、低噪音、使能源能夠多元化利用的多項優點。本研究針對氨–水型吸收式冷凍系統進行架設與實驗測試，以模擬出的汽車排氣溫度為系統的驅動熱源，分析各種變因對系統性能的效應，其主要目的提高系統效率，同時探討其應用於汽車之可行性。系統中的主要元件包含蒸發器、冷凝器、氣體發生器、精餾器、吸收器、儲液槽、泵等。實驗的操縱變因包括氣體發生器溫度、冷凝器風扇頻率、吸收器冷卻水入口溫度及鹵水溫度等。所探討的變因包括冷凍能力、系統性能係數（COP）等。 實驗結果可知氣體發生器的溫度取決於供應熱量之多寡，當氣體發生器溫度在100℃∼135℃範圍內上升時，系統的冷凍能力也從3000kJ/hr上升至5100kJ/hr（約為0.24∼0.4冷凍噸）。而系統的COP值卻由0.19上升至0.24後略微下降至0.23。因此得知在特定的操作條件下，會有一最佳氣體發生器溫度值，此時系統的COP值為最大。吸收器冷卻水入口溫度也影響系統的性能，當吸收器冷卻水入口溫度由8℃上升至24℃時，吸收器的散熱量下降，系統的冷凍能力也約由8000kJ/hr下降至4000kJ/hr，進而影響系統COP值也伴隨著下降。由實驗結果也可看出冷凝器風扇頻率越快則造成較低的冷凝溫度，系統的高壓部分隨著冷凝溫度的降低而降低，而系統的冷凍能力與COP值隨著冷凝溫度的降低而上升。鹵水溫度的高低也影響系統性能表現，當鹵水溫度下降時，由於與蒸發器內冷媒的溫差變小，導致熱傳結果較差，系統的COP值與冷凍能力也隨之而降低。 將文獻中所提有關COP值及冷凍能力的變化情形與本研究所得的結果比較後趨勢均相近。惟冷凍能力及COP值較低的結果，顯示仍有許多改善空間及問題待克服，才能提高系統效率與應用於汽車的可行性。
並列摘要
Absorption refrigeration system drives many benefits, encompassing economy, environmental protection, low noise as well as energy multiplicity. The study aims at constructing aqua-ammonia absorption refrigeration and experimental evaluation and adopts a simulated exhausted motor temperature as driven heat source, to analyze varied effects caused to the system. The study primarily intends to promote systematic efficiency and examine feasibility of applying to motors. The system is mainly composed of an evaporator, a condenser, a generator, a rectifier, an absorber, a storage tank and pumps. The controlled variables are the fan frequency, the generator temperature, the pump frequency, and the water/glycol solution temperature. The cooling capacity and coefficient of performance (COP) of the system is also investigated. The experimental results manifested that the generator temperature is mainly affected by the supplying heat source, and the cooling capacity also increases from 3000kJ/hr to 5100kJ/hr (approximately 0.24-0.4 ton) while the generator temperature increases in the range of 100ºC~135ºC. Nevertheless, the value of the cooling capacity slightly decreases to 0.23 after increasing from 0.19 to 0.24, and thereby it is recognizable that the value of the coefficient of performance (COP) of the system would be the highest in a particular operational condition, producing an optimum value of the generator temperature. The absorber cooling water/glycol solution temperature would also affect properties of the system when the temperature rises from 8℃ to 24℃, and the quantity of heat transfer from the absorber descends; the cooling capacity of the system also declines from 8000kJ/hr to 4000kJ/hr, causing a decrease of the value of COP. Meanwhile, this experiment manifests that the faster fan frequency generates lower condensed temperature, and the high pressure of the system decrease with condensed temperature. The value of water/glycol solution temperature also affects the properties. While the water/glycol solution temperature descends, the heat transfer would become worse due to the small differences with the refrigerant within the evaporator; therefore, the value of COP and cooling capacity would also decrease. Compared with the results of mentioned study, the tendency of predicted results about COP and cooling capacity of system is similar to that of the literatures. The result of cooling capacity and low COP provide a gap to be improved and overcome in order to promote systematic efficiency and feasibility in motor application.