Heat Transfer to a Liquid Flowing Down Vertical Wires Hanging in a Hot Gas Stream: an Experimental Study of a Now Means of Thermal Energy Recovery

摘要

This paper describes an experimental examination of a novel scheme of sensible heat recovery from a hot gas stream by means of a direct gas-to-iquid contact operation. A non-volatile liquid is fed onto wires hanging in the gas stream to flow down each wire, taking the form of an axially uniform, tubular film or a composite of teardrop-shaped beads axially aligned on the wire and short tubular films each onnecting two neighboring beads. A set of experiments have been performed to investigate the heat transfer from an upward vertical flow of heated air to a counter flow of a silicone oil down a single wire vertically hung in the air flow. It is demonstrated that a sufficiently high temperature effectiveness is achieved with the silicone oil at a fall distance of the order of 1 m. When the liquid flow rate per wire and the fall distance are both prescribed in common, a higher temperature effectiveness may be obtained with the uniform annular-film flow mode on a thicker wire than with the "string-of-beads: flow mode on a thinner wire despite a higher gas-to-liquid overal heat transfer coefficient available in the latter.