Simultaneous integration, control and enhancement of both fluid flow and heat transfer in small scale heat exchangers: A numerical study ☆ L. Léal a,b , F. Topin c , P. Lavieille a,b , L. Tadrist c , M. Miscevic a,b, ⁎ a Université de Toulouse, UPS, INPT, LAPLACE (Laboratoire Plasma et Conversion d'Energie), 118 route de Narbonne, F-31062 Toulouse cedex 9, France b CNRS, LAPLACE, F-31062 Toulouse, France c Aix-Marseille Université-CNRS Laboratoire IUSTI, UMR 7743, 5 Rue Enrico Fermi, Marseille 13453, France abstract article info Available online 29 October 2013 Keywords: Heat transfer enhancement Dynamic deformation Wall morphing Narrow channel Compactness, efficiency and control of heat exchangers are of great interest in many processes. A technological breakthrough must be achieved to go further in their ability to respond to needs. A new concept of heat exchang- er is proposed. It consists in dynamically deforming at least one of the walls of a low hydraulic diameter channel. Heat transfer and mass flow rate enhancements are investigated in single-phase flow. When the deformation is a progressive wave with a relative amplitude of 98.5% and frequency of 50 Hz, it generates a flow having a mass velocity of up to 510 kg·m -2 ·s -1 . Although the Reynolds number is low the heat transfer coefficient is enhanced by up to 450% compared to a straight channel. © 2013 Elsevier Ltd. All rights reserved. 1. Introduction The increasing demands of new and effective mixing and heat transfer technologies for various industrial fields such as engineering, chemicals, pharmaceuticals, biochemistry and chemical analysis, associ- ated with the increasing need to control highly exothermic or explosive chemical reactions, have contributed to the development of new and effective technologies involving low diameter channels. It is nowadays common to meet chemical or thermal systems whose channels have sub-millimetric hydraulic diameters. If these systems can increase the compactness, one major drawback is the difficulty to disturb the bound- ary layers as flow is mostly laminar in such small devices. Consequently, the net gain in terms of mass or heat transfer is due to the increase in the exchange surface as the mass and heat transfer coefficients are usually reduced compared to classical systems. Moreover such devices lead usually to very high-pressure drops. Indeed, to address the problem of mass and heat transfer coefficients, high velocities of the fluid must be achieved, leading to high pressure losses and consequently to large mechanical power consumed by the pump which is generally located further more or less far upstream the heat exchanger. Thus, the flow distribution in the heat exchanger may be difficult to control and additional pressure losses are generated. Besides the performance issue, the operating conditions of heat exchangers and chemical reactors are generally constrained, since the mass and heat transfer coefficients are closely related to the fluid flow rate. Integrating the pump to these systems appears thus as a solution to the architectural optimization of chemical or thermal process. One possible way to simultaneously disturb the boundary layers and to inte- grate the pumping function within the heat exchanger is to generate a dynamic deformation of the channel's wall. Indeed, using a progressive wave deformation produces the motion of the fluid (peristaltic pump) and the disturbance of the boundary layers. The literature lacks investigation of the effects of dynamic deforma- tions on flow and heat transfer inside channels. Several authors have considered flow inside squeezed thin films like Langlois [1]. However, only a few of them have also analyzed heat transfer such as Hamza [2], Bhattacharyya et al. [3] or Debbaut [4] but, in these works, the squeezing was not of oscillatory type. Nakamura et al. [5] investigated numerically the influence of the wall oscillation on the heat transfer characteristics in a two dimensional channel. Khaled and Vafai [6] considered flow and heat transfer inside incompressible oscillatory squeezed thin films. Kumar et al. [7] recently studied heat transfer inside circular millimetric tubes with static and moving sinusoidal cor- rugated walls. Numerical analyses were performed to study the effect of spatial wavelengths (λ = 1/2, 2/3, 1, 2 mm), Reynolds number (1–120) and amplitude (1–20% of tube diameter, D 0 ) on heat transfer and pressure drops. The heat transfer coefficient for the moving wavy walls had a higher value for all frequencies compared to the static wall case (up to 35–70%). A sharp decrease in pressure drop (by a factor of 1.2 to 5) was also obtained at high amplitudes. Mainly, heat transfer and pressure drop values apparently changed erratically with wall frequency. No general trend of heat transfer and pressure drop values in respect to operating parameters was found. Several authors performed studies about the effect of heat transfer on peristaltic flow such as Ali et al. [8], Nadeem and Safia [9], Srinivas International Communications in Heat and Mass Transfer 49 (2013) 36–40 ☆ Communicated by J. Taine and A. Soufiani. ⁎ Corresponding author at: Université de Toulouse, UPS, INPT, LAPLACE (Laboratoire Plasma et Conversion d'Energie), 118 route de Narbonne, F-31062 Toulouse cedex 9, France. E-mail address: marc.miscevic@laplace.univ-tlse.fr (M. Miscevic). 0735-1933/$ – see front matter © 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.icheatmasstransfer.2013.10.004 Contents lists available at ScienceDirect International Communications in Heat and Mass Transfer journal homepage: www.elsevier.com/locate/ichmt