Experimental and numerical investigation of thermal characteristics of a novel concentric type tube heat exchanger with turbulators

Abstract

SUMMARY In this study, the heat transfer performance and friction characteristics of a novel concentric tube heat exchanger with different pitches of helical turbulators were investigated experimentally and numerically for a Reynolds number range from 3000 to 14 000. An experimental system was established to obtain experimental data. The numerical simulations were performed by using a three dimensional numerical computation technique, a commercial CFD computer code. Then, the heat transfer performance and friction characteristics of several helical turbulators were compared. The experimental, numerical and empirical correlation results were in a good agreement with each others. As a result, the heat transfer enhancements using turbulators were 2.91, 2.41, 2.18 and 1.99 times better than the smooth tube for pitch distances of p = 20, 40, 60 and 80 mm, respectively. Copyright © 2012 John Wiley & Sons, Ltd.

Investigation of heat transfer enhancement in a new type heat exchanger using solar parabolic trough systems

“…The uncertainties of experimental results for m · , Q · , h, Nu, Re, D P and f were estimated to be ±4.3%, ±4.3%, ±4.4%, ±4.7%, ±4.7%, ±5.9% and ±6.7%, respectively. In the same conditions, the experimental results can be reproduced for these uncertainty ranges in this study [12].…”

“…The hot air and cold water enter in the opposite ends of the heat exchanger and flow in opposite directions. The hot air flows in the inner tube, while the cold water flows in the outer tube [12]. The diameters of the inner tube (D) and outer tube are 40 mm and 69 mm, respectively.…”

“…1 shows the schematic diagram of the experimental setup connected to the data logger and analysis system, positions of the thermocouples, other measurement instruments, a concentric tube heat exchanger and used tools [12]. The inlet bulk air at 22 C from the laboratory room was directed through a 0.6 kW blower adjusted flow rates by changeable motor speed via the inverter (ABB ACS350 model) located at the system.…”

“…where, r is density, u velocity, m dynamic viscosity, p pressure, k thermal conductivity, T temperature and cp specific heat [12].…”

“…Moreover, there were not any convergence problems. Thus, this uniform grid was used for all range of Re number to solve each equation of the continuity, momentum and turbulent [12].…”