Numerical simulation study on the heat transfer of a spiral tube receiver designed to a thermal power tower. Toufik Arrif *, Abdelfettah Belaid, Amor Gama, and Rida Zarrit Unité de Recherche Appliquée en Energies Renouvelables, URAER, Centre de Développement des Energies Renouvelables, CDER, 47133, Ghardaïa, Algeria *arriftou@yahoo.fr Abdelmadjid Chehhat Faculty of Science and Technology University Laghrour Abbess Khenchela, Algeria achehhat@gmail.com Abstract— in this work the heat transfer of a spiral tube receiver exposed to concentrated solar radiation is studied theoretically. The simulations were performed using Fluent6.3.26 for two different sections at several Reynolds numbers: 100, 300, 500, 700, and 1000 to see the effect of the inlet velocity on the outlet temperature. The effect of the inlet temperature is also discussed by varying the inlet temperature of the water of 293K to 313K. The results show that the average temperature of the heating and adiabatic surface (inner wall) is decreasing when the velocity inlet is increasing. The outlet temperature of a semicircular section is higher than that of the circular section, but the Nusselt number of this one is twice higher as that of semicircular section and it’s due to the geometrical shape of the section. Keywords- Key words: heat exchanger, heat transfer, spiral tube I. INTRODUCTION In a solar thermal power tower system, the cylindrical receiver (heat exchanger tube) is a key component for solar concentration system. The average temperature of the inner wall of the tube is an important operating parameter [1]. The main obstacle to the development of solar tower technology is the significant investment required by the construction of a field of heliostats and tower. Naphon [2] studied the characteristics of the heat transfer and flow of a horizontal spiral coil tube by numerical and experimental method. In actual solar thermal power, because of the different concentrated solar radiation and different incident angle, the heat transfer is uneven along the circumference. The local temperature, heat ﾀux and heat transfer coefficient of the tube receiver need to be obtained when the solar plant operates normally [3]. Concerns the solar heat exchanger fluid (water/solar) high temperature we designed a spiral tube geometry with two variable sections. The aim is to seek optimum designs of spiral ducts for solar applications where the cross section area is fixed. The computational domains in Figures 7 and 8 were created in GAMBIT (2.3. 16) software then simulated in FLUENT (6.3.26) and then will be integrated and simulated in TRNSYS. The solar receiver (heat exchanger) presented in this work consists of one single spiral tube arranged vertically. In this study we simulate heat transfer spiral tube operating with water as the working fluid and one half circumference of the tube receiver receives the solar radiation energy, and the second half is supposed adiabatic surface covered with heat insulator. To compare the two geometries, numerical simulations were carried out for fixed cross section area and pipe length. The results of numerical simulations in this document show the particular distribution of Nusselt number and temperature. II. MODEL DEVELOPMENT In this study, incompressible laminar Newtonian ﾀuid ﾀows in- side a spiral duct with two cross sections is taken into account. The conｿgurations of in-plane spiral ducts and their respective cross section schematic are displayed in Fig.1and 2; the detailed geometric parameters are presented in Table I. In this work we consider one side of tube called the heating surface receives constant heat ﾀux from the solar radiation Q Net = 10000 W/m2, and the other side is called adiabatic surface 978-1-4673-6392-1/13/$31.00 ©2013 IEEE 1135 4th International Conference on Power Engineering, Energy and Electrical Drives Istanbul, Turkey, 13-17 May 2013 POWERENG 2013