Ceramic high temperature plate fin heat exchanger: Experimental investigation under high temperatures and pressures

Ceramic materials enable operation in high temperature and harsh environments and can so exceed the capabilities of comparable metal heat exchangers. For the use in power plant applications and high temperature processes a heat exchanger has to operate under both high temperature and high pressure levels. So far, the operation of a ceramic heat exchanger under such conditions has not been investigated. This work presents a ceramic heat exchanger prototype with modified offset-strip-fin design, which was experimentally investigated in a specifically designed test environment. Experimental tests were conducted with air as a heat transfer fluid at temperatures up to 800 °C, absolute pressures up to 5 bar and norm volume flows up to 160 Nm3 h-1. The functionality under high temperatures and absolute pressures could be proven. The paper reports measured performances of the heat exchanger prototype, for which heat transferred up to six kilowatt and effectiveness up to 97 % has been achieved. A comparison of Colburn and friction factors with correlations from literature was conducted, too. Good agreement for Colburn prediction of the flue gas channels could be shown, but the investigation also reveals a limited applicability for the friction factor and the Colburn factor of the process gas channel.