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

• Concentric tube heat exchanger with coiled turbulators was used a parabolic trough solar system.
• The numerical simulations were performed by using a three dimensional CFD computer code.
• The numerical, experimental and empirical correlation results were in good agreement.
• Reducing heat exchanger sizes and increasing heat transfer were obtained.
• Heat transfer enhancements were 2.28, 2.07 and 1.95 times better than the smooth tube.

Hydrogen production from solar energy is one of the most candidates in near future. Concentric tube heat exchangers have been used in concentrated solar power (CSP) plants such as parabolic trough system. In order to be reduced heat exchanger sizes and heat transfer enhancements, in this study, the heat transfer and friction characteristics of a concentric tube heat exchanger with different pitches of coiled wire turbulators were investigated experimentally and numerically. An experimental system was established in order to obtain experimental data. The numerical simulations were performed by using a three dimensional CFD computer code. The experimental, numerical and empirical correlation results were compared with each others for a Reynolds number range from 3000 to 17 000. The results were correlated in the form of Nusselt number as a function of Reynolds number and Prandtl number. The heat transfer enhancements using turbulators were 2.28, 2.07 and 1.95 times better than the smooth tube for pitch distances of p = 15, 30 and 45 mm, respectively.