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Show 2.3 Excess Enthalpy Combustion Technology One of the practical method for controlling the heat flux distribution is High-cycle Regenerative combustion System, herein called the H R S . The system has been developed by Nippon Furnace Kogyo Kaisha Ltd., of Japan. One of the typical applications of H R S is shown in Fig. 2.7. This system has a pair of regenerators for transporting the heat from the flue gas to the fresh incoming air to the combustion chamber. In this system, while one side of burner is firing, the other burner uses flue gas to heat up the matrix of regenerator. The firing side is then switched with the other side, and during this time, the regenerator matrix of the first side is heated-up. Regenerative heat exchange method itself is a well known method for obtaining high temperature air in order to raise the flame temperature in furnaces, such as glass melting furnaces. Rotating regenerator, e.g. Ljungstrome heat exchanger[3] has also been used as a air preheater. One of the key feature of H R S is that the cycling time with alternate firing can be varied to provide the suitable conditions for a particuler application. In the present study it was varied in the range of 20 to 30 seconds. Combustion Air 4 way Valve //v Furnace Fig. 2.7 High-cycle Regenerative Combustion System (HRS) Heat accumulated in the regenerator needs alternate periodic firing, so that the short cycling can be applied to form the high and homogeneous temperature field in the combustion chamber. Excess enthalpy combustion enhances the thermal field. Alternate periodic firing uniformizes the thermal field. The periodic alternate firing at high frequency can simultaneously provide an increase in air temperature and decrease in waste heat loss. The most desirable matrix of the regenerator is the volume during which enough heat is accumulated during the cycle. In our present H R S studies, a ceramic honeycomb type regenerator, which has large heat surface area per unit volume, was employed. 6 |