Concentric Annular U-type Loop Thermosyphon Solar Boiler Design And Investigation Of Its Heat Transfer Characteristics

Steam between 150℃C·200℃is widely used in the industrial fields.Energy consumption of industrial boilers occupies a large proportion of total energy consumption in society. Due to the poor operation and less efficient of industrial boilers, and the lack of effective environmental protection facilities, the emission causes more environment pollution. Therefore, developing solar energy boiler, then a partial substitute for industrial boilers, is important for the fields of industrial heating energy-saving and emission reduction. Therefore, this article has investigated the application of the parabolic trough collector (PTC) and the loop thermosyphon in the field of solar high-temperature steam generation, and developed a new type of a concentric annular U-type loop thermosyphon solar boiler system.This paper describes the current status of the industrial steam heating field and solar thermal utilization of the latest developments, compares solar power and solar steam with economics,and finally a comprehensive analysis of solar energy in the high-temperature steam drawn tremendous research value.In this paper systematically designed a solar boiler system with the size of 62.7kw and evaporation capacity of 50kg/h, and summed up a set of design method of the solar boiler. To reduce system's cost, we have made some significant improvements based on the technology of PTC:Designed a new type concentric annular U-type collector tube as collector element,and built heat transfer model for it. The theoretical efficiency of it is 66%, after revised, the efficiency is 59%.Base on meeting the efficiency requirements of the System design, the cost of the collector tube is reduced to 1/15 of the straight-through vacuum collector tube.During the experiment,combined with modular design, obtained a more accurate and easy to install type of single-glass concentric annular U-type trough solar collector module, its efficiency is closer to the straight-through vacuum collector tube.To solve the problem of layouting pipe on two relative motion systems,and improve the reliability of system,we designed a four-bar linkage for fixing pipeline.After completion of the concentric annular U-type loop thermosyphon solar boiler's built, we start a preliminary experimental for its start-up characteristics.And through the analysis of experimental data, we obtained the start-up characteristics of the system in the actual working environment in north China, and the method of calculating the overall efficiency of the system. Through the summary of experiment's physical environment factors, we added some factors in the calculation of system efficiency, such as edge effects of the PTC,icing on reflector and other causes reduced system efficiency.