Steam Ejector Report

According to the experimental test system as shown in Fig. 3 and two ejectors as shown in Fig. 4, the performance of the steam ejector was investigated under the condition of the primary steam temperature ranged from 40 °C to 70 °C, and the secondary steam temperature was set at 10 °C, 15 °C, 20 °C and 25 °C, respectively. The experimental results of the effects of the operating temperatures, nozzle exit position and the area ratio of the ejector on the performance of the steam ejector were summarized as follows.

At the beginning of the study, a tentative experiment was carried out with the Ejector 1. The experimental results are illustrated in Fig. 5, when the primary steam temperature is 70 °C and the secondary steam temperature is 25 °C.

When the nozzle is set at a new position in the mixing chamber, the duct formed between the nozzle exit and the mixing chamber will be changed. This directly affects the mass flow rate of the secondary steam entrained by the primary steam. To investigate the effect of NXP on the performance of the steam ejector, a movable nozzle mechanism was designed and fabricated as shown in Fig. 4. The zero point of the NXP is defined as the nozzle exit was at the mixing chamber inlet. The experiments were carried out at three different positions, NXP = 50 mm, NXP = 100 mm and NXP = 150 mm. Figure 9 shows the NXP effect on the COP and critical condensation temperature for the Ejector 1 at the primary steam temperature ranging from 40 °C to 70 °C and the secondary steam temperature set at 25 °C. The experimental results of the steam ejector with different NXPs are compared at the same primary steam temperature. The COP of the steam ejector with NXP = 100 mm is much higher than that of the steam ejector with NXP = 50 mm and NXP = 150 mm. This means that there is an optimum NXP for the maximum COP of the steam ejector with the NXP ranging from 50 mm to 150 mm, which should be investigated further in the future. It also can be seen that the COP decreased as the primary steam temperature increased at a given NXP. Moreover, the results shown in Fig. 9 indicate that the critical condensation temperature when the NXP = 50 mm is lower than that when NXP = 100 mm and NXP = 150 mm in most cases. The distinction of the critical condensation temperature between NXP = 100 mm and NXP = 150 mm is not obvious. Considering the COP and the critical condensation temperature for each NXP at the same condition, the steam ejector has a more superior performance when NXP = 100 mm compared to other two