Design and fabricate heat exchanger for downdraft gasifier / Mohd Hefni Abdul Hadi

A heat exchanger is a device that used heat transfer to transfer of internal thermal energy between two or more fluids available at different temperatures level. The objectives of this project are to design and fabricate heat exchanger for downdraft gasifier system, develop and fabricate a mechanism by lab-scaled dimensions and investigate temperature requirement in gasification process. Heat exchanger is part cooling process in gasification system. Where, the cooling process is a part of producer gas treatment before it can use as a fuel or others applications. The selection of shell tube heat exchanger in this project due to high operating temperature and low fabrication cost. In selection of material, aluminium is the most appropriate materials for the fabrication of heat exchanger due to higher thermal conductivity (k = 237m.K), lightweight (density, p = 2702 kg/m3), corrosion resistance, and moderate cost. At the design stage, to achieved the optimal design some important parameter has been calculated such as required surface area (0.06m2) and number of tube (n = 4). After the design stage, there are few fabrication processes involves in fabricated of heat exchanger which is cutting, joining, assembly and installation process. In testing stage, the temperature of producer gas has been reduced in range of (39.1°C — 43.5°C). Then, through the observation of gas flame the result shown the colour of gas was change from red to blue, this indicated the gas volume metric efficiency for syngas was increased due to the temperature drop in the cooling stage.