Infrastructure Engineering - Research Publications

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Author: Aye, Lu × Author: Stewart, Donald × Start date: 2000 × End date: 2009 ×

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    Simulation study of a down-draft wood gasifier used to produce thermal energy for tea drying
    Jayah, T ; Aye, L ; Fuller, RJ ; Stewart, DF (ANZSES Australia & New Zealand Solar Energy Society, 2000-11-29)
    A detailed computer model has been developed using the physical and chemical phenomena in gasification for a down-draft biomass gasifiers. The model has been used to investigate the effects of operational and design parameters on reactor performance in terms of the composition of the output gas and the hot gas efficiency. The results obtained from the simulation study are the effects of fuel moisture content, particle size, feed rate, reactor load and capacity on hot gas efficiency. The model has been validated using experimental data available in the open literature. The hot gas efficiency of a particular down-draft throated gasifier designed to generate thermal energy for tea drying is predicted to be approximately 86%.
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    The potential of wood gasifiers for tea drying in Sri Lanka
    JAYAH, TH ; FULLER, R ; AYE, L ; STEWART, D (RERIC, 2001-12-01)
    One of the reasons for the higher production cost of tea in Sri Lanka compared to other countries is the high specific energy consumption. In Sri Lanka, 38% more energy is used to produce one kilogram of tea compared to India, largely because of the use of inefficient wood-fired air heaters. Gasifiers have been proposed as an alternative method of providing the hot air used for drying. A locally built gasifier has been tested and found to have a conversation efficiency of 80%, which is comparable to that of an imported unit. The heat loss of local gasifier was found to be between 11.5-14% of the input energy. An analysis shows that the life cycle cost of energy produced by the gasifier is US$ 3.00 per GJ, which is 8% less than the cost of energy from a conventional wood heater. Wood consumption is also reduced by 12%. Some transfer of gasifier technology to the crematoria industry in Sri Lanka has already occurred and this enhances the prospect of the successful introduction of this technology to the tea industry.
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    Computer simulation of a downdraft wood gasifier for tea drying
    JAYAH, TH ; AYE, L ; FULLER, RJ ; STEWART, DF (Elsevier, 2003-10-01)
    A gasifier has been fabricated in Sri Lanka for the tea industry, but there is a lack of knowledge of the effect of certain key operating parameters and design features on its performance. Experimental testing of the design under various conditions has produced data that has then been used to calibrate a computer program, developed to investigate the impact of those parameters and features on conversion efficiency. The program consists of two sub-models of the pyrolysis and gasification zones, respectively. The pyrolysis sub-model has been used to determine the maximum temperature and the composition of the gas entering the gasification zone. The gasification zone sub-model has been calibrated using data gathered from the experiments. It was found that a wood chip size of 3–5 cm with a moisture content below 15% (d.b.) should be used in this gasifier. Feed material with a fixed carbon content of higher than 30% and heat losses of more than 15% should be avoided. For the above parameters, the gasification zone should be 33 cm long to achieve an acceptable conversion efficiency.