scholarly journals EXPERIMENTAL STUDY ON HEAT TRANSFER AND FRICTION OF TURBULENT SWIRLING AIR FLOW THROUGH ABRUPT EXPANSION

2010 ◽  
Vol 38 (3) ◽  
pp. 717-734
Author(s):  
Alsaied Khalil ◽  
A.E. Zohir ◽  
A.M. Farid
Author(s):  
Yangbo Deng ◽  
Fengmin Su ◽  
Chunji Yan

The solar energy converter in Concentrated Solar Power (CSP) system, applies the solid frame structure of the ceramic foams to receive the concentrated solar radiation, convert it into thermal energy, and heat the air flow through the ceramic foams by convection heat transfer. In this paper, first, the pressure drops in the studied ceramic foams were measured under all kinds of flow condition. Based on the experimental results, an empirical numerical model was built for the air flow through ceramic foams. Second, a 3-D numerical model was built, for the receiving and conversion of the solar energy in the ceramic foams of the solar energy converter. Third, applying two aforementioned numerical models, the numerical studies of the thermal performance were carried out, for the solar energy converter filled with the ceramic foams, and results show that the structure parameters of the ceramic foams, the effective reflective area and the solar radiation intensity of the solar concentrator, have direct impacts on the absorptivity and conversion efficiency of the solar energy in the solar energy converter. And the results of the numerical studies are found to be in reasonable agreement with the experimental measurements. This paper will provide a reference for the design and manufacture of the solar energy converter with the ceramic foams.


Author(s):  
Chadia Haidar ◽  
Rachid Boutarfa ◽  
Mohamed Sennoune ◽  
Souad Harmand

This work focuses on the numerical and experimental study of convective heat transfer in a rotor of a discoidal the machine with an eccentric impinging jet. Convective heat transfers are determined experimentally in steady state on the surface of a single rotating disk. The experimental technique is based on the use of infrared thermography to access surface temperature measurement, and on the numerical resolution of the energy equation in steady-state, to evaluate local convective coefficients. The results from the numerical simulation are compared with heat transfer experiments for rotational Reynolds numbers between 2.38×105 and 5.44×105 and for the jet's Reynolds numbers ranging from 16.5×103 to 49.6 ×103. A good agreement between the two approaches was obtained in the case of a single rotating disk, which confirms us in the choice of our numerical model. On the other hand, a numerical study of the flow and convective heat transfer in the case of an unconfined rotor-stator system with an eccentric air jet impinging and for a dimensionless spacing G=0.02, was carried out. The results obtained revealed the presence of different heat transfer zones dominated either by rotation only, by the air flow only or by the dynamics of the rotation flow superimposed on that of the air flow. Critical radii on the rotor surface have been identified


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