Steam Ejector

Using the aforementioned experimental setup as shown in Fig. 1, three ejectors as shown in Fig. 2 were investigated to determine the effects of the operation temperatures, nozzle exit position, and the diameter of the constant area section, dcas, on the working performance of the steam ejector powered by extra low-temperature heat source. In this investigation, the working performance of the steam ejector mainly includes system COP, cooling capacity and critical condensing temperature [40], Tc*. For the test, the generating temperature, Tg, ranged from 40 °C to 70 °C, and the evaporating temperature, Te, was set at 10 °C and 15 °C, respectively.

Figure 3 shows the variation of system COP and cooling capacity with the condensing temperature,

Moreover, it can be seen that the cooling capacity could gain 685.4 W when Tg = 65 °C and 482.8 W when Tg = 55 °C. With the increase in generating temperature, the cooling capacity decreased at first and then increased when the generating temperatures ranged from 40 °C to 70 °C. The experiment was repeated under the same conditions. Figure 4 illustrates the effect of the generating temperature on the system COP, cooling capacity and critical condensing temperature of the steam ejector when the generating temperatures ranged from 60 °C to 70 °C. As shown in Fig. 4, the system COP increased first and then decreased with the generating temperature increasing and there existed a maximum value of 0.277 at Tg = 63 °C. The variation tendency of the cooling capacity was similar to that of the system COP, but the maximum value of 734.4 W at Tg = 67 °C. The total pressure of the primary flow in the nozzle was relatively low with the generating temperature set under these conditions. The reason for the

As shown, the system COP could achieve 1.259 when Tg = 40 °C and Te = 15 °C. When the evaporating temperature was 15 °C, the system COP was much higher than that when the evaporating temperature was set at 10 °C. But the system COPs were almost the same when Tg = 65 °C. In other words, the cooling capacities were nearly equal when Te = 10 °C and Te = 15 °C at this condition. When Te = 15 °C, the cooling capacity decreased first and then increased with the generating temperatures ranging from 40 °C to 70 °C. This variation tendency is similar to that when Te = 10 °C. The worst performance occurred when the generating temperature was 65 °C, which was 720.3 W. In Fig. 5, it also can be seen that the critical condensing temperature when Te = 15 °C is a little higher than that when Te = 10 °C in most cases. The maximum difference between the two conditions is 3.7 °C when Tg = 55