Experimental study on heat transfer enhancement caused by the flow-induced vibration of a prism inside a channel

Abstract

An experimental study, using water as the working fluid, has been performed to analyze whether a passive system based on flow-induced vibration is a feasible option to enhance heat transfer in the laminar confined regime. The experimental setup consisted of a 1.5 m tall vertical channel manufactured on methacrylate (square cross-section of 25 mm x 25 mm) and a tethered square section buoyant prism (10 mm x 10 mm x 25 mm) placed inside the channel. The tethered prism was allowed to move freely (like an inverted pendulum) as a consequence of its interaction with the incoming flow. An aluminum block placed in the channel walls around the prism heated the water with a constant wall temperature of 60 C. The flow Reynolds number (Re) based on the prism cross section length was varied between 80 and 800. Three prisms with three different prism-to-water density ratios (m*) were used in the experiments: 0.56, 0.70 and 0.91. The case with the prism anchored to the walls was considered also. Regarding heat transfer, all cases were compared to the reference case which consisted of the clean channel with no prism present. The flow velocity was characterized using a Particle Image Velocimetry System. The electric power supply to the heated walls was recorded and the spatial distribution of water temperature was measured in a transversal plane downstream of the heated walls. It was found that the heat transfer enhancement provided by this system, as compared to the clean channel with no prism present, was very much dependent on Re. For example, at the lowest Re 80, the improvement on the Nusselt number (Nu) was negligible for all cases. At highest Re 800, the improvement on Nu was 100% for the case of prism-to-water density ratio of 0.91, and 66% for the case of the prism anchored to the walls. This suggests that, when thinking of practical engineering applications, passive systems based on flow-induced vibration might represent a feasible alternative, because of its simplicity, to active systems that require a more complex implementation that includes a motor to move the prism. The simplest setup (the prism anchored to the walls) also yields a significant, if smaller, heat transfer enhancement.

Comparison of three-dimensional flow mixing via pulsation and dynamical stirring: application to the mixing of parallel streams at different temperatures

“…For example, regarding pulsating flows, the following references, among others, could be referred to Ji et al (2008), Mulcahey et al (2013), Yu et al (2014), Krishnan et al (2016) and Martin et al (2018). Regarding prism motion, some relevant references are: Celik and Beskok (2009), Singh et al (2009), Reyes et al (2015), Kumar Chauhan et al (2016), Sastre and Velazquez (2017), Ortega-Casanova and Lai (2018), Clemente et al (2019) and Valeije et al (2020).…”

Research on Vibration and Heat Transfer in Heat Exchanger with Vortex Generator

“…Based on the traditional HE, the elastic coil pipe heat exchanger (ECPHE) [4,5] was developed by using the elastic pipes instead of the rigid pipes. However, unlike the traditional HE, the ECPHE is not devoted to the prevention of vibrations; it can enhance the heat transfer by flow-induced vibrations [6][7][8]. For the ECPHE, the vibration excitation and control are the key factors affecting the heat transfer efficiency and the service life [9,10].…”

Vibration Response and Stress Analysis of Planar Elastic Tube Bundle Induced by Fluid Flow

“…Meanwhile, the tube vibration occurs because of the periodic alternating force. It is verified that this vibration is beneficial to heat transfer [18][19][20]. In this paper, the flow-induced vibration by shell-side is studied because the effect of tube-side on the vibration of planar elastic tube bundle can be ignored [21].…”