  In the presence of elastic forces, even dilute polymer suspensions can
exhibit erratic flow fluctuations even when the viscous forces dominate over
the inertial forces, which occur at vanishing-low Reynolds numbers (Re). This
phenomenon is called Elastic Turbulence (ET). ET can be generated in
small-scale laboratory settings and is relevant to enhancing mixing efficiency
and heat transfer in microfluidic devices. In this study, we investigate the
hydraulic and thermal properties of a dilute polymer solution under ET
conditions characterized by inflow conditions of vanishing Re and high
Weissenberg numbers (Wi). We carry out extensive direct numerical simulations
of the 2D curvilinear channel flow of an Oldroyd-B viscoelastic fluid using
Rheotool. We analyze the variations of friction factor and Nusselt numbers
along the serpentine channel to reveal the global and local characteristics of
ET. Based on Wi, we identify three regimes. First, for 0 < Wi < 3, we observe
roughly 10% heat transfer enhancement accompanied by roughly 5% reduction of
friction factor compared to laminar flow, known as polymer-induced thermal
conductivity enhancement. Second, for 3 < Wi < 5, we observe a sharp linear
increase of heat transfer (roughly 30%) at the cost of up to 15% enhanced
friction factor. Finally, in the fully developed elastic turbulence regime (Wi
> 5), we observe up to 60% heat transfer enhancement accompanied by reduced
friction factor. The substantial enhancement of heat transfer with increasing
Wi is mainly attributed to the increasing intensity of the elastic instability
resulting from the balance between normal stresses and streamlined curvatures.
