Experimental investigation on heat transfer characteristics of staggered tube bundle heat exchanger immersed in oscillating flow

摘要

Owing to the growing demands to develop sustainable energy, ocean energy is attracting increasing attention for the large amount of renewable, available, and potential energy resources stored in the ocean. An experimental system was constructed to study the heat transfer characteristics of staggered tube bundle heat exchanger immersed in oscillating flow. The results revealed that the instantaneous horizontal and vertical velocities of the oscillating flow exhibited a periodic fluctuation trend. Moreover, the cycle-averaged velocity and the external heat transfer coefficients were clearly affected by the wave height, whereas the wave period had little effect. To quantitatively describe the heat convection of staggered tube bundle heat exchanger in oscillating flow, a correlation of the Nusselt number that accounted for the combined effects of the wave parameters (including the wave height and wave period), water depth, and location depth of the submersed tube bundles was proposed. Comparisons with various correlations revealed that previous correlations could not describe the external heat convection in oscillating flow accurately. The newly proposed correlation was proven to predict the external Nusselt number with an acceptable accuracy under various testing conditions, which benefitted the design of the seawater heat exchanger.