Özet:

Two-phase flow is preferred in many industrial applications where high heat flux is present and/or required because of its higher heat transfer coefficient compared to single-phase flows. However, there are some adverse effects that will reduce the life of the system and its components, as well as risk the safe operation and its benefits. In this study, the effects of conical coiled springs as an in-tube element aimed at the elimination, or actually minimization, of said adverse effects are investigated experimentally. In this study, a 2-phase flow system was used, with the test section comprised of a straight horizontal tube with forced convection boiling. The effects of equally spaced conical spring arrays having different pitches as an in-tube heat transfer enhancement element on heat transfer and pressure drop in 2-phase flow were investigated. Fluid supply flow rate and pitches of conical springs inserted into the tube were selected as study parameters, and experiments were made under constant operating pressure, constant inlet temperature, constant heat input, and fixed outlet restrictions to investigate the effects of conical springs. Four different heat transfer surface configurations are used. Experiments showed that the minimum point shifted to the right on the curve with the increase in heat input, and the mass flow rate at a given pressure drop observed is directly proportional to the thermal power. The highest pressure drop in the 2-phase flow region is observed with tube 4 (10 mm pitch) and tube 3 (20 mm pitch), while the lowest pressure drop is with tube 1.

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