INVESTIGATION OF FOULING PROCESS FOR CONVECTIVE HEAT TRANSFER IN AN ANNULAR DUCT

Experimental and theoretical study is summarized of fouling process on heat transfer surface. An automatic monitoring system was set up to determine impact of fouling. Experiments were performed with artificial hard water as a working fluid at different conditions. Some important parameters including water temperature, wall temperature, flow velocity, water hardness and alkalinity were testified to make sure their influences on the fouling process on heat transfer surfaces. The ranges of water temperature, wall temperature, flow velocity and water hardness are between 20～50℃, 50～75℃, 0.5～2.0m/s, 200 ～ 1000mg/L (as CaCO3), respectively. All the experimental data were recorded continuously and the fouling resistances were calculated accordingly. Furthermore, an analysis was conducted to understand mechanism of fouling on heat transfer surface according a new physical model of fouling process. Good agreements can be observed between calculated results and experimental data

INVESTIGATION OF FOULING PROCESS FOR CONVECTIVE HEAT TRANSFER IN AN ANNULAR DUCT

Experimental and theoretical study is summarized of fouling process on heat transfer surface. An automatic monitoring system was set up to determine impact of fouling. Experiments were performed with artificial hard water as a working fluid at different conditions. Some important parameters including water temperature, wall temperature, flow velocity, water hardness and alkalinity were testified to make sure their influences on the fouling process on heat transfer surfaces. The ranges of water temperature, wall temperature, flow velocity and water hardness are between 20～50℃, 50～75℃, 0.5～2.0m/s, 200 ～ 1000mg/L (as CaCO3), respectively. All the experimental data were recorded continuously and the fouling resistances were calculated accordingly. Furthermore, an analysis was conducted to understand mechanism of fouling on heat transfer surface according a new physical model of fouling process. Good agreements can be observed between calculated results and experimental data

Deformation and Recrystallization Behavior of the Cast Structure in Large Size, High Strength Steel Ingots: Experimentation and Modeling

Constitutive modeling of the ingot breakdown process of large size ingots of high strength steel was carried out through comprehensive thermomechanical processing using Gleeble 3800® thermomechanical simulator, finite element modeling (FEM), optical and electron back scatter diffraction (EBSD). For this purpose, hot compression tests in the range of 1473 K to 1323 K (1200 °C to 1050 °C) and strain rates of 0.25 to 2 s−1 were carried out. The stress-strain curves describing the deformation behavior of the dendritic microstructure of the cast ingot were analyzed in terms of the Arrhenius and Hansel-Spittel models which were implemented in Forge NxT 1.0® FEM software. The results indicated that the Arrhenius model was more reliable in predicting microstructure evolution of the as-cast structure during ingot breakdown, particularly the occurrence of dynamic recrystallization (DRX) process which was a vital parameter in estimating the optimum loads for forming of large size components. The accuracy and reliability of both models were compared in terms of correlation coefficient (R) and the average absolute relative error (ARRE)