The heat transfer phenomenon within volumetric receiver of concentrated solar tower using Diamond Like Carbon (DLC) material

Siti Sarah , Zahari (2013) The heat transfer phenomenon within volumetric receiver of concentrated solar tower using Diamond Like Carbon (DLC) material. Project Report. UTeM, Melaka. (Submitted)

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Abstract

This project aimed to investigate the effectiveness of using Diamond Like Carbon (DLC) as volumetric receiver of Concentrated Solar Tower. Volumetric receiver, the type of solar absorber that is mostly studied which able to operate at high temperature, above 900K, the material therefore should be one that is durable to high temperature, have high absorptivity and high thermal conductivity for efficient heat transfer rate. Therefore the current system used non-oxide ceramics; Silicon Carbide (SiC) as the material. However, some problem have been identified while using SiC, which sometimes the occurrence of hot spots have melted the front surface eventhough the air outlet temperature has not yet reached the material melting temperature. Some had stated that this may due to the instabilities of flow and the inability of the material to spread the peak heat because of low effective thermal conductivity. Hence, in this project the applicability of DLC as the receiver material has been investigate whether DLC receiver able to overcome this problem. In this project, the study was conducted by performing 3D simulation using ANSYS Fluent platform towards heat transfer within DLC receiver module with several characteristics in order to observe the temperature distribution on the surface, the outlet temperature and analyzing the ability of DLC module to reduce hot spot. In the simulation, a small area is concentrated with higher heat flux to initiate hot spot. After that calculation continued with homogenous 1MW/m2 heat flux and the result at the end of calculation was observed whether hot spot reduced and vanish. All receivers with 1.35mm, 1.55mm and 3.5mm mean cell size for 3000W/m.K thermal conductivity of DLC are able to overcome the hot spot phenomena while producing high outlet air temperature of 2300K. This concludes that with very high thermal conductivity of material, the hot spot phenomena are able to be overcome regardless of the porous characteristic of the receiver. Hence, DLC of 130W/m.K to 3000W/m.K thermal conductivity is the suitable candidate for volumetric receiver.

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