**6. Conclusions**

that the sum of the specific works *w*vp,ac and *w*rco,t (i.e., the total specific work *wt*) has a minimal value (maximum saving in the total work sum *wt*). This minimum value depends on the value of *T*ci and it is less than the corresponding *w*vp,wac according to the temperature *T*ci by 38.5, 33.9, and 28.9% at Δ*T*vpi of 12, 10, and 8°C for *T*ci of 20, 30, and 40°C, respectively. Also, it is seen from **Figures 13** and **14** that *wt* is maximally higher than the minimal value corresponding to *T*ci by 3% when Δ*T*vpi is 4°C higher than its value at which the minimal total specific work occurs. On the contrary, the saving in the steam lost increases depending on *T*ci in the range of 5–7%. Therefore, it is more advantageous to choose values for Δ*T*vpi higher than those at which the minimal total work occurs in the range of 4°C, as it results in fairly less lost steam rate to be drawn by the vacuum pump and inconsiderable increase in the total work. Higher values than 4°C cause inconsiderably small increase in saving the lost steam, but the total work is significantly raised.

*Saving percent in specific work due to refrigeration cooling of steam condenser air cooler. ———,* T*ci = 20°C;*

*Specific work dependence on the air temperature at vacuum pump entrance.* **———,** wvp,wac*;* ———, wvp,ac*;*

**Figure 13.**

**Figure 14.**

**238**

*———,* T*ci = 30°C; ………* T*ci = 40°C.*

**………,** wrco,t*;* **—. —,** wt.

*Low-temperature Technologies*

The current work is concerned with the use of vapor compression refrigeration system (VCRS) for chilling cooling water used with the air cooler of the steam plant condenser (SPC). A thermodynamic analysis is developed for working out the performance of the hybrid system of VCRS and SPC. The results obtained using this analysis showed that subcooling of the SPC condensate can cause considerable reduction in steam rate associated with the air induced by the vacuum pump. However, this is possibly avoided as it represents heat loss in the condensate heat content, which should be compensated in the plant boiler. In addition, the results of this work led to drawing the following conclusions for condensate subcooling of 3°C, which represents a reasonable and practical subcooling of the condenser condensate.

