可調式噴嘴噴射器最佳操作性能的設計與分析

Abstract

太陽能噴射式製冷系統的操作溫度會隨太陽能輻射熱與環境溫度變化，使用傳統固定式噴嘴噴射器無法使性能達到最佳化。本研究設計一支可調式噴嘴噴射器，藉由調整針的位置改變主噴嘴喉部面積。如此一來，調整針的位置即可使噴射器適應操作溫度的變化。對於特定的A3/At來說，當操作溫度改變時藉由調整主噴嘴喉部面積使冷凝器溫度等於臨界溫度，可以使噴射器達到最佳性能。本研究以回歸分析計算出可調式噴嘴噴射器的最佳A3/At與操作溫度的關係式. A3/At=0.71701Tg-0.0196Te+0.70234Tc+0.00204TgTe-0.01185TgTc-0.00257TeTc-43.9477。以實際操作觀點來看，如果實驗量測到產生器溫度、蒸發器溫度、冷凝器溫度時，使用此關係式可調式噴嘴噴射器即可調整到最佳的A3/At，系統即可操作在最佳性能。

For solar-driven ejector refrigeration system, operating temperature may change with the variation in solar radiation and ambient temperature. Thus, a conventional fixed throat area ejector may not work at its optimal performance. In this study, a variable ejector has been designed, which incorporates a needle into the ejector. This allows the primary throat area to be changed by adjusting the position of the needle. By means of this controlled needle modification, an unsteady operating temperature can be taken into account. For a given throat area, an optimum generator temperature exists at which the critical condenser temperature is the same as the actual condenser temperature. A regressive equation, related to the corresponding optimum throat area ratio with respect to the operating conditions, is obtained. A3/At=0.71701Tg-0.0196Te+0.70234Tc+ 0.00204TgTe-0.01185TgTc-0.00257TeTc-43.9477. From the practical operating point of view, if the generator, evaporator or condenser temperature is measured out, the ejector can be adjusted to the corresponding optimal throat area ratio using the equation. The system then operates with optimal performance.