Influence of Horizontal Tube Bundle Arrangement on Flow and Heat Transfer Properties of Oily Wastewater Spray Falling Film

Abstract

Recently, the spray heat exchanger became an important technology in a sewage source heat pump (SSHP) to recover thermal energy from oily wastewater. Hence, it's necessary to study the heat transfer properties and its enhancements. Among all of the influential factors, the arrangement of the tube bundle is a critical factor that influence the liquid film flow of the falling film, and further has a great impact on heat transfer. Therefore, in this paper, a three-dimensional numerical model of the arrangement of triangular tube bundles is established, using a glycerin-water mixed solution to simulate oily wastewater. The flow pattern of the liquid film under different tube row modes and the influence of heat transfer effects are compared, and the temperature inside the liquid film is analyzed. It was found that there is an obvious difference in the falling film flow outside the horizontal tube between the triangular tube bundle arrangement and the inline tube bundle arrangement. The liquid film flow in the triangular arrangement is more unstable and has a greater impact on the heat transfer of the upper half of the tube. The same phenomenon is observed for the tube bundle below the top row. The local heat transfer coefficient along the circumferential direction of the triangular arrangement is greater than that of the in-line arrangement. Besides, both of the tube bundle arrangements have the phenomenon that the local heat transfer coefficient decreases with the increase in oil content.