Study On The Shallow Geothermal Energy Resources Evaluation In Kaifeng Urban Area

Relying on the ground-source heat pump technology including groundwater and pipe heat exchanger system, shallow geothermal energy resources are exploited and utilized by converting the clean and renewable tow taste heat guahtity ranging from earth surface to two hundred metres to the pollution-free and sustainable high taste energy; in addition, the features of great reserves and on-site utilization make this new sources of energy form widely expanded and used worldwide. However, a series of problems like decreasing efficiency and environmental pollution arise in the development of shallow geothermal energy resources for not having investigated and evaluated the exploration area systematically before utilization. Thus, it seems absolutely necessary to carry out regional investigation and evaluation of shallow geothermal energy resources in work areas.Based on the current situation and the progress of shallow geothermal energy resources research and considered the situation and issues in Kaifeng city, this article has made a full study of geological conditions and drogeological conditions in research area, then builds two suitability regionalization evaluating systems and two weight systems of groundwater-source heat pump and ground-source heat pump of Kaifeng area respectively by using AHP methods and making AHP program of comprehensive evaluation of the shallow geothermal energy through MATLAB software.The function of the DTM analysis and management of property base etc of GIS is applied to vectorize and partition all of the evaluating factors and assign the attribute for the graphs of these factors. Then all the graphs are superposed to generate new files, the attribute data are abstracted by the function of spatial analysis module and according to the comprehensive evaluating method, the research area is partitioned into three different types: most suitable zone、suitable zone and worst suitable zone and output by the means of GIS visualization. Finally, the suitability regionalization evaluation of the groundwater heat pump and gourd source heat pump of Kaifeng city is achieved. According to the necessary physical parameters of Volumetric Method and drilling data and based on the current situation in research area, thermal reservoirs are divided into sand layer、silt layer and silty-clay layer. The physical parameter attribute base of different layers in research area is established through interpolation of the parameters of different layers by using the function of DTM analysis and management of attribute base modules of GIS. Thus, the shallow geothermal capacity both in the zones of vadose and saturation of different modes of occurrence is calculated based on these attribute data. at last, the calculation and evaluation of shallow geothermal capacity in Kaifeng area is achieved through superposing of these geothermal capacity values of different types.The heat transfer coefficient of pipe heat exchanger is completed on the ground of principle of heat exchanger power and calculation of thermo-physical parameters of soil and gained by analyzing of these thermo-physical parameters via experimental data. Based on the heat transfer coefficient, the single hole heat exchanger power and the power values in whole research area are evaluated.The investigation and evaluation work lies a firm foundation for the future research and provide great value of basis for the development and establishment of shallow geothermal energy resources management and environment protection policies in this area.