Performance of parabolic trough collector having rotating receiver: Effect of elliptical insert and hybrid nanofluid

Abstract

Summary This study considers three parabolic trough collector models with rotating receiver tubes and elliptical inserts of two orientations and one with a smooth receiver tube. Hybrid nanofluid is considered as a working medium by mixing copper oxide and aluminum oxide nanoparticles in water. Computational experiments are performed with a 1% concentration in terms of vol. of hybrid nanofluids by considering a mixture of copper oxide and aluminum oxide nanoparticles in water (aluminum oxide 25%‐ copper oxide 75%, aluminum oxide 50%‐ copper oxide 50%, and aluminum oxide 75%‐ copper oxide 25%). Rate of flow for the simulation is considered to vary from 0.016 to 0.033 kg/s. Again, this study focuses on utilizing rotating receiver tubes with a varying velocity of 0‐15 rad/s to overcome the stratification of high temperature at the surface. Results show that enhanced values for the temperature at outlet, heat transfer coefficient, and thermal efficiency are noted for a model with elliptical inserts of major diameter 28 mm (longitudinal orientation) at 15 rad/s receivers speed for nanofluid‐1 (aluminum oxide 75%‐ copper oxide 25%) at 0.033 kg/s. The highest increment in heat transfer coefficient, as well as thermal efficiency for the model with a 28 mm major diameter elliptical insert (longitudinal orientation), is 44.21% and 29.21% respectively. Highlights Use of a spinning receiver reduces the problem of uneven temperature distribution at receiver surface. Maximum 375 K outlet temperature is noted at 15 rad/s for elliptical insert of diameter 28 mm (longitudinal orientation) at 0.016 kg/s. The elliptical insert received the maximum thermal efficiency rating of 82.03%. An elliptical insert in receiver increases pump work by 18.13% than smooth receiver.

Thermal performance evaluation of parabolic trough collector having different inserts and working with hybrid nanofluid

“…A Copper tube of length 2 meters is constructed. The inner circumferential diameters, as well as outer circumferential diameter, are 70 mm as well as 66 mm respectively [2]. One tube composed of glass, which is perfectly evacuated, is considered over the copper tube to increase the reduction in thermal losses.…”

“…Balls of spherical shape and elliptical inserted for diameter as well as the major diameter of 48 mm are considered respectively. The reason is that in the earlier studies with these kinds of inserts, the best outcomes are noted with 48mm of maximum diameter [2,25]. For the elliptical inserts, two values of minor diameter 12mm and 24mm are being simulated.…”

“…concentration of hybrid nanoparticles in water (CuO 25 %-Al2O3 75%, CuO 50%-Al2O3 50%, and CuO 75%-Al2O3 25%) The dimensions of the studied models and other parameters for the comparative study are listed in Table 1. At a time 20 equally placed inserts are considered, they are interlinked by a rod of 6mm diameter [2]. The thermal, as well as physical properties of heatcarrying liquid are as in Table 2.…”

“…Flow of hybrid nanofluid inside tube obeys Navier-Stokes equations also the momentum, energy, and continuity equations, shown in the following equations [2].…”

“…content in water was 58.2% and 56.5%, respectively, at 5000 Reynolds number. Chakraborty et al [2] conducted a numerical examination for trough collector by choosing hybrid nanofluid of 1% volume content in water, obtained by mixing a different combination of Al2O3 and CuO particles. Elliptical inserts of varying dimensions and orientations were considered for rotating receiver tubes (velocity range=0-15 rad/s).…”