Study On Thermal Performance Of Biomass Cooking-stoves With Heat Collector Tube

The history of using biomass cooking stove as basic cooking instrument in the rural area of China has been thousands years. The formation of cooking-stove keeps changing with the evolution of daily life, which is influenced by the economic development. In recent decades, people are requiring higher and higher standard of living comfortability and functionality due to the rapid development of domestic economy and social environment. However, residents in some of the rural areas in China are still using the old (traditional) style of masonry cooking stove, which cannot completely fulfill the requirement in terms of heating efficiency, variability in functionality and appearance.The majority of the current researches upon cooking stove provide dimensions of the structure elements purely based on experiment; however, the theoretical heat transfer of the cooking stove is not sufficiently investigated, as a result, an accurate guideline for the structure of the cooking stove and improvement of heat efficiency cannot be determined. The cooking stove with heat collector tube studied in this thesis optimizes the structure of the traditional biomass cooking stove and improves the thermal efficiency, in addition, a heat collector tube is added, which is able to absorb the excessive heat that cannot be used by cooking or heating. The absorbed portion of heat can be used to provide hot water uesd in the heating system. The research is mainly based on experiment, a heat transfer model is built as well, which calculates the thermal and heat transferring properties of the cooking stove with heat collector tube.A normal biomass cooking stove is used as a reference to the one with heat collector tube. By the burning experiment, the thermal properties of the two types of cooking stove can be obtained. The heating ability of the two types of stoves are analyzed by comparing the intensity of heat supplying during the heating and elaborating phases of the two types of stoves, after that the allocation of heat inside the stove is calculated based on the test data. The energy consumed by cooking, heat collector tube, smoke and dissipated heat are calculated; The heat distribution shows as:heat for cooking19.25%, heat in smoke28.75%,heat in heat collector tube42%, heat loss coused by gas0.9%,heat loss coused on surfuce of stove4.5%, heat loss in ash0.3,heat loss coused by incomple burn of fuel4.3%. The heat balance of heating for cooking, for heated kang and for waste heat is analyzed, which can be regarded as a fundamental research for further optimization of heating providing system in rural residential buildings.An internal heat transfer numerical model is built for the cooking stove with heat collector.The model consists of four modules,which are the structure module, the internal heat transfer module, for the stove the model of burning of the fuel and the heat transfer module for the heat collector tube. Note that reasonable simplification has been done to the model. The model is capable of deriving temperature of water in the stove, water in the heat collector tube and smoke as the outputs of the basic parameters of the stove, type of the fuel and environmental parameters. The results from the model are in consisting with experiment, indicating that the model is able to be applied for design or optimization of cooking stove.