Experimental transient natural convection heat transfer from a vertical cylindrical tank

In this paper heat transfer experimental data is presented and compared to general correlations proposed in the literature for transient laminar free convection from a vertical cylindrical tank. The experimental data has been obtained from heating and cooling experiments carried out with a cylindrical full-scale hot water storage tank working under real operating conditions. The experimental device and the data acquisition system are described. The calculation procedures established to obtain the experimental values of the heat transfer coefficients, as well as the data reduction process, are detailed. The local convection and radiation heat transfer coefficients are obtained from different heating power conditions for local Rayleigh numbers within the range of 1×105–3×108. The great quantity of available experimental data allows a detailed analysis with a reliable empirical base. The experimental local convection heat transfer coefficients are correlated and compared to correlations proposed in open literature for engineering calculations.

► Experimental data of transient local convection heat transfer coefficients from a cylindrical tank for heating and cooling processes is obtained.
► The transient behaviour of the convection coefficients is dependent on temperature difference evolutions between the surface and the air.
► The Nu·Ra−1/4 ratio decreases proportionally in (Ts−T∞)−0.9.
► A new correlation based on the semi-infinite region theory for laminar transient free convection is proposed.