10.07.2015   EUROSUN 2008

Alternative Designs of the Drake Landing STTSs

1.3. Design Criteria

After the initial study of the authors [6], it was hoped that an examination of alternative STTS designs would help to better characterize the charging performance of the current STTS concept. It would also serve as a proving ground for the Exergy Charge Response index. As we wished to maintain the external shape of the STTSs, the study also holds specific bearing to the optimal design of large horizontal thermal energy stores.

1.4. New Concepts

Figure 2. Original Concept (Tank 1) Figure 3. Repositioning of Inlet Figure 4. Removal of Center Baffle

and Outlet Ports (Tank 2) (Tank 3)
Подпись: Figure 2. Original Concept (Tank 1) Figure 3. Repositioning of Inlet Figure 4. Removal of Center Baffle and Outlet Ports (Tank 2) (Tank 3)

Seven concepts of the STTSs are presented and studied in this work, including the original design. These are illustrated below in Figures 2 to 8, showing cross-sectional views of each design.

Figure 5. Addition of Upper and Lower Baffles (Tank 4)

Подпись:

Figure 6. Addition of Second Inlet Port (Tank 5)

Подпись:The first four new concepts (Figures 3 to 6) were developed from sequential changes made to the original STTS (Figure 2). The continued usage of the large horizontal baffles has both practical and analytical benefits. Not only are they simple to implement physically, the reduced meshing complexity of the baffled tanks allows for increased confidence in the validity of the CFD analysis carried throughout.

Figure 7. Horizontally Partitioned STTS (Tank 6)

Figure 8. Horizontally Partitioned STTS with Slotted Plenums (Tank 7)
Подпись: Figure 7. Horizontally Partitioned STTS (Tank 6) Подпись: Figure 8. Horizontally Partitioned STTS with Slotted Plenums (Tank 7)

The use of large horizontal baffles to encourage thermal stratification in thermal energy stores has been examined elsewhere [2], and has proven to serve useful particularly for vertical tanks, where the inlet/outlet flows are parallel to the direction of stratification. For Tanks 4 and 5, the purpose of the baffles is to allow the velocity of the inlet fluid to reduce significantly before coming into to contact with the larger region of the tank, thereby minimizing thermal mixing.

Figures 7 and 8 illustrate a different configuration altogether, using vertical baffles to horizontally partition the STTS into four nodes. Tank 7 also incorporates a slotted plenum at the inlet region to reduce turbulent mixing caused by the initial jet plumes. The designs were created principally from qualitative objectives, without a particular design guide for horizontally partitioned thermal energy stores. A more concrete study of such systems is under research at Shanghai Jiao Tong University [9].