OCR Text |
Show 2. Computer Simulation of Honeycomb used as the regenerator media During the regeneration period, it is estimated that the regenerator media reaches a higher temperature near the combustion gas inlet and a lower temperature toward the combustion gas outlet. In addition, the temperature distribution of the regenerator media changes at every moment. Thus, to understand the heating mechanism, we simulated the changes in the temperature distribution. Supposing that the honeycomb is used as the regenerator media, it is obvious that a thicker wall thickness increases the maximum stored heat (heat stored during an infinite storage tim~). Based on this fact, we designed a simulation model and studied the heating mechanism to determine an optimum wall thickness given the specified changeover time. 2-1 Simulation model (1) Divided Honeycomb Model The simulation was done as follows. The honeycomb was divided into n sections along the flow path of the combustion gas, and the gas was supplied from one side for a given time (at a changeover time of P seconds), while the air was supplied from the other end for the same period. The model is shown in Fig. 1 schematically Since the gas and air generally have different heating and cooling capabilities, the temperature distribution obtained by supplying the gas and air only once differs from that obtained when supplying them several times. Thus, the gas and air must be supplied several times to execute computations until the temperature distribution of the honeycomb just before the changeover has the same profile as the previous data. The honeycomb temperature is calculated using the six equations shown below. The heat quantity removed each second from the combustion gas is calculated as follows: q = CpgG( Tt - Te ) x lsee [keal] (1) The heat quantity transferred each second to the honeycomb from the combustion gas is calculated as follows: q = hAC To - T. ) x lsee [keal] (2) The heat quantity the honeycomb gains each second is calculated as follows: q = Cpm V. ( T. - T.o ) x lea [keal] (3) From equations (1), (2), and (3), the temperature of the combustion gas in the honeycomb cell is calculated as follows: Tg = 2Cp.G( Cp.V. + hA )Tf + hACp~V~T.o 2C pg G( Cp.V. + hA )hACp.V. (4) The combustion gas temperature at the outlet of the honeycomb cell is calculated as follows: Te = 2To - Tt (5) Thus, the temperature of the honeycomb cell is calculated as follows: Where Cpg Cpm : Specific heat of the combustion gas Specific heat of the honeycomb - 2 - (6) (kcal/m3 °C) (kcal/m3 °C) |