Study of heat transfer characteristics of wire-and-tube heat exchangers

Free convection heat transfer from a number of wire-and-tube heat exchangers was experimentally investigated. The experiments were carried out at different inclination angles that ranged from 0.0° (horizontal test) to 90° (vertical test). The spacing-to-diameter ratio of wire (sw) was varied from 2.0 to 5.7, while the spacing-to-diameter ratio of tubes (st) was varied from 5.0 to 12.1. The height of the exchangers were in the range 0.83 m to 1.105 m. The effect of a vertical flat plate near to a vertical heat exchanger on a heat transfer rate was also studied. The distance between the flat plate and the exchangers (x) was varied from 1.67d to 6.67 d (where d is the tube diameter). It was found that the heat transfer rate decreases upon increasing the inclination angle regardless of the spacing-to-diameter ratios. The heat transfer rate decreases as the spacing-to-diameter ratio of the wire sw decreases. Also results show that the Nusselt number increases with the distance x between the vertical flat plate and the vertical exchanger. A general relationship that relates the heat transfer rate to various parameters was developed.