Heat transfer characteristics of a round block impervious graphite heat exchanger

Abstract The round block graphite heat exchanger is one of the three most popular types of impervious graphite heat exchangers with a market share of 50%. The heat transfer characteristic was experimentally studied. First, the effects of velocities of cold and hot medium on overall heat transfer coefficient were studied. Second, distributions of thermal resistance of hot medium, cold medium, graphite, and resin were illustrated. Finally, the Nusselt numbers for the shell and tube side were individually formulated based on the Reynolds and Prandtl number. The result shows that the overall heat transfer coefficients rose as the velocities of the cold and hot mediums increased. The thermal resistance of cold medium was the dominant one because of leakage flow and corresponding deteriorative heat transfer. In addition, thermal resistance of resin is slightly higher than that of the wall indicating that the thickness of the resin layer is relatively large. The experimental values of shell-side heat transfer coefficient are much less than the theoretical ones with a maximum error of 44%. The experimental numbers of tube-side heat transfer coefficient are equal to theoretical values.