## 4 Results and Discussion
### Temperature Distributions  
The temperature distributions of the three structural solar chimneys are shown in Figure 4. For the combined solar chimney in the natural ventilation mode (S1 CSC), the temperature distribution of the air in the hot channel was lower and uniform at a given air temperature of 298 K. At this time, the inlet temperature of S1 CSC was 300 K and the air temperature in the hot channel was lower than that of S2 CSC. When the ambient temperature was 303 K, the temperature close to the inclined storage wall began to rise. The temperature distribution was also uniform with a modicum of an increase both for S1 CSC and S2 CSC. However, when the ambient temperature was 308 K, the near-wall temperature at the inclined part of S1 CSC increased significantly, which was much higher than that of S2 CSC. The temperature at the outlet could reach up to 320.4 K. The temperature in the air channel was relatively evenly distributed for S2 CSC with little difference from the ambient temperature. There was obvious overheating in the air channel when the ambient air temperature was 313 K. As the inlet temperature of S1 CSC was constant and lower than that of S2 CSC (equal to the ambient temperature), the air temperature of the hot channel was relatively low when the ambient temperature was 308 K or 313 K. However, the cooling load of the room increased if operated in S1 CSC.  
Figure 3: The comparison of the simulation data and the experimental data: (**a**) a Trombe wall [30] and (**b**) an inclined solar chimney at 45\({}^{\circ}\)[14].  
Figure 4: Temperature distributions and the mass flow rate under different ambient temperatures in the summer: (**a**) T\({}_{\rm a}\) = 298 K; (**b**) T\({}_{\rm a}\) = 303 K; (**c**) T\({}_{\rm a}\) = 308 K; and (**d**) T\({}_{\rm a}\) = 313 K. (For all heat maps, the left boundary is the glass cover and the right boundary is the wall).  
Figure 5 shows the changing of the average air temperature in the channel and the temperature of the internal walls with the outdoor ambient temperature. It could be concluded that the temperature of the CSC was lower whereas that of the Trombe wall and the IRSC was relatively higher in the same ambient temperature condition. Owing to the structure composition, the hot air of the CSC was mainly located in the inclined part. It had little influence on the internal wall temperature and the indoor temperature and the problem of overheating could be alleviated to an extent. In contrast, the temperature near the wall of the Trombe wall and the inclined-roof solar chimney was higher, which had an influence on the indoor thermal environment. In addition, the overheating phenomenon was more obvious at a higher ambient temperature.  
As shown in Figure 5, the average air temperature in the channel and the storage wall of S1 CSC were at the lowest values of 300.8 K and 304.6 K when the ambient temperature was 298 K. These values were 316.2 K and 320.4 K, respectively, for S2 CSC when the ambient temperature was 313 K. By comparing the temperature distribution of different structures, it could be indicated that the average air temperature in the channel and the internal wall temperature of S1 TW and S2 TW were always higher than those of S1 CSC, S2 CSC, and the IRSC. The Trombe wall structure was more likely to cause indoor overheating in the summer whereas the combined solar chimney structure had the lowest temperature in the air channel and storage wall, which could effectively alleviate overheating in the summer.