Simulations were performed for the cases where the total gas flow for gas to solid mass flow ratio of 10 is distributed between the main gas inlet and auxiliary gas inlets at 0.25 and 0.5 m. This results in the scheme, where high heat transfer area would be available over a distance of 0.5 m in the duct, increasing heat transfer rate and solid temperature. Since the optimum gas to solid flow ratio at the main gas inlet was found to be 1 from the previous section, gas flow rates at the auxiliary entries of 0.25 and 0.5 m were varied as shown in Table 1 to determine optimum hot gas distribution scheme to maximize solid temperature at 1 m. Results of the simulation are plotted in Fig. 4 and it is evident that maximum solid temperature at 1 m is obtained, when the total gas flow rate is distributed in the ratio of 1:1:8. The difference in solid temperature at 1 m with changes in gas distribution pattern is around 4 °C. It is evident from Fig. 4 that the maximum solid temperature achieved with three gas inlets is around 5 °C and 23 °C greater than that obtained with two gas inlets and single gas inlet, respectively, indicating an improvement in heat recovery. Such simulations were performed for a gas to solid mass flow ratio of 5 also and results are shown in Fig. 5. Distribution of gas between inlets in the ratio of 1:1:3 has been found to achieve a solid exit temperature of 70 °C, an increase of 4 °C compared with gas entry at two points only. A common feature in Figs. 4 and 5 is the steep increase in solid temperature near 0.5 m due to introduction of hot gas through auxiliary inlet at 0.5 m.
Simulations were performed for the cases where the total gas flow for gas to solid mass flow ratio of 10 is distributed between the main gas inlet and auxiliary gas inlets at 0.25 and 0.5 m. This results in the scheme, where high heat transfer area would be available over a distance of 0.5 m in the duct, increasing heat transfer rate and solid temperature. Since the optimum gas to solid flow ratio at the main gas inlet was found to be 1 from the previous section, gas flow rates at the auxiliary entries of 0.25 and 0.5 m were varied as shown in Table 1 to determine optimum hot gas distribution scheme to maximize solid temperature at 1 m. Results of the simulation are plotted in Fig. 4 and it is evident that maximum solid temperature at 1 m is obtained, when the total gas flow rate is distributed in the ratio of 1:1:8. The difference in solid temperature at 1 m with changes in gas distribution pattern is around 4 °C. It is evident from Fig. 4 that the maximum solid temperature achieved with three gas inlets is around 5 °C and 23 °C greater than that obtained with two gas inlets and single gas inlet, respectively, indicating an improvement in heat recovery. Such simulations were performed for a gas to solid mass flow ratio of 5 also and results are shown in Fig. 5. Distribution of gas between inlets in the ratio of 1:1:3 has been found to achieve a solid exit temperature of 70 °C, an increase of 4 °C compared with gas entry at two points only. A common feature in Figs. 4 and 5 is the steep increase in solid temperature near 0.5 m due to introduction of hot gas through auxiliary inlet at 0.5 m.
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