Mathematical Model of Combustion and Heat Transfer in Boiler by Reciprocating Combustion of fuel gas in Porous Medium

Abstract

This paper presents the study of heat transfer enhancement to cooling water pipe by using multiphase combustion technique.  This can be done by using One way flow combustion (OWFC) in a porous medium at which a water tube is inserted. The OWFC yields higher heat transfer coefficient than the single-phase system. However, The OWFC has a problem concerning a narrow operating range, which has not been solved yet. If supply velocity is higher than a limit value the flame blow-off occurs. This problem can be solved by using a cyclic flow reversal of combustion (CFRC) technique in a porous medium instead of one way flow combustion. Mathematical model of the combustion system is formulated and solved by a numerical method.  Attention was focused on the influence of the dominating parameters, i.e., flow velocity, half period and equivalence ratio on the formation of temperature profiles in the porous body. Results show that by changing the flow direction of the mixture a regular time interval, the combustion system could be operated at relatively high flow velocity without a flame blow-off when compared with the OWFC system. The yielded heat transfer coefficient for the CFRC system is higher than that of the combustion system without the porous medium by a factor of 3 to 5 at the same operating condition.