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• New correlations for Nu number of ethanol ice slurry in a vertical slit channel. • The effect of flow direction on the values of α coefficients was investigated. • For laminar flow, the melting process has a greater effect of on α coefficient. • For turbulent flow, the convection process has a greater effect on α coefficient. • The upward flow, high ice mass fraction increase the αcoefficients. The article concerns the heat transfer process of ethanol ice slurry during downward and upward flow in a vertical slit channel (3x35.8x700 mm) under constant heat flux density conditions. Experimental studies were conducted for three initial concentrations of ethanol (X vai = 10.5 %, 13.2 %, 15.8 %) and mass fractions of ice of 0 ≤ x s ≤ 30 %. For upward flow, heat transfer coefficients were 6–14 % higher than for downward flow. For laminar flow, a greater effect of the melting process was observed, and for turbulent flow, the convection process had a greater effect on heat transfer coefficients. For laminar flow, the heat transfer coefficients of the ice slurry can be 200 % higher than the corresponding values for the carrier fluid. In turbulent flow, the corresponding increase in heat transfer coefficients did not exceed 15 %. For generalised non-Newtonian flow of ice slurry, criterion relationships were proposed for calculating heat transfer coefficients, taking into account the effect of the concentration of the carrier fluid, mass fractions of ice, its melting process, as well as the nature and direction of the flow. [ABSTRACT FROM AUTHOR]

The paper presents the results of experimental studies of the heat transfer process on the outer surface of longitudinally finned tubes. Experimental values of heat transfer coefficients under free and forced convection conditions were calculated for low air flow velocities. Two air flow patterns were analysed, i.e. airflow parallel and perpendicular to the axis of the pipe. The mean values of heat transfer coefficients obtained during the study amounted to 2-8.5 (W m-2 K-1) under free convection conditions, 4.5-19 (W m-2 K-1) for forced transverse flow and 4-11 (W m-2 K-1) for forced convection along the axis of the tube. Experimental values of heat transfer coefficients for transverse flow around the tube were 22% higher than heat transfer coefficients for airflow along the axis of the tube. The paper lists the dimensionless relationships which can be used to calculate the values of the heat transfer coefficient under free and mixed convection conditions, with transverse and longitudinal air flow around the outer surface of vertical longitudinally finned tubes. [ABSTRACT FROM AUTHOR]

Abstract: The paper presents the results of experimental research on heat transfer of ice slurry during its flow through tubes of circular, rectangular and slit cross-sections. Moreover, the work discusses the influence of solid particles, type of motion and cross-section on the changes in the heat transfer coefficient. The analysis presented in the paper allows for an identification of the criterial relations used to calculate the Nusselt number for laminar and turbulent flow, taking into account elements such as phase change, which accompanies the heat transfer process. Ice slurry flow is treated as a generalized flow of a non-Newtonian fluid. [Copyright &y& Elsevier]