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Show 2-2 Calculation conditions Table 1 shows the honeycomb specification assumed when calculating the temperature distribution. The specification is that of a standard honeycomb whose outside diameter and length are 144 mm and 150 mm respectively. Table 2 shows the specification such as the combustion gas, air, and changeover time. 2-3 Simulation results (1) Temperature distribution inside the regenerator media as a function of time. The combustion gas and air are supplied to the honeycomb from the left and right ends for 60 seconds, and this cycle is repeated several times. Fig. 4 shows the temperature distribution of the honeycomb just before the changeover, where each point on the honeycomb gains the same value of the previous cycle. The left half indicates the temperature distribution of the air and the right half indicates that of the combustion gas. The numbers attached to the line indicate the elapse of time since the changeover. The figure clearly shows that the heat is removed from the combustion gas and the gas temperature drops sharply. However, the figure also indicates that just before the changeover, the combustion gas temperature hardly drops due to the least endothermic capability of the heated honeycomb. The air flown into the honeycomb obviously gains a sharp temperature rise, indicating approximately 900°C in the middle section of the honeycomb about 10 seconds after the changeover. Just before the changeover, however, contrary to the combustion gas, the air temperature does not rise so much since the honeycomb is cooled and its heating capability drops. (2) Hot air and exhaust gas temperature Fig. 5 shows the change in air temperature at the left end of the honeycomb just after one changeover and just before the next changeover. Note that the numbers indicate the changeover time. It is obvious that the 30-second changeover time hardly contributes to a decrease in tempera ture even just before the changeover. While, the 60-second changeover time produces a remarkable temperature drop just before the changeover. This indicates that heat stored in the honeycomb has almost run out. Fig. 6 shows the change in combustion gas (exhaust gas) temperature at the right end of the honeycomb just after one changeover and just before the next changeover. Note that the numbers indicate the changeover time as w~ll. The 30 second and 60 second changeover times yield 570°C and 740 °C just before the changeover. This means that the honeycomb has a little more margin for storing capability since the combustion gas temperature is 900°C. (3) Time mean hot air and exhaust gas temperature Fig. 7 shows the time mean hot air temperature TA obtained by varying the changeover time from 20 to 60 seconds on three types of honeycombs having lengths of 100 mm, 150 mm, and 200 mm. In the 100 mm honeycomb. TA drops markedly as the changeover time is extended. However, the 200 mm honeycomb does not indicate a remarkable drop. Fig. 8 shows the time mean exhaust gas temperature TE obtained in the same manner as TA. While in the 100 mm honeycomb, TE rises grea tly as the changeover time increases, the 200 nun honeycomb hardly increases at all. This data shows that the 100 mm honeycomb has a lower heat storage capacity, and that the capacity of the 200 uun honeycomb is sufficient. - 4 - |