Heat transfer in the melting of ice slurry during flow in a vertical slit channel

•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 (3x35.8x700mm) under constant heat flux density conditions. Experimental studies were conducted for three initial concentrations of ethanol (Xvai = 10.5 %, 13.2 %, 15.8 %) and mass fractions of ice of 0 ≤ xs ≤ 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.