Study On Combined Supply System Of Solar-geothermal Energy In Tibet Area

There is a current global energy shortage problem.Due to its special geographical location,Tibet's primary energy shortage is very serious.In addition to the increasing energy consumption of oxygen supply systems in Tibet,Energy efficiency and renewable energy use are more important.Based on the characteristics of geothermal energy and solar energy in Tibet,the paper studies the solar geothermal energy combined energy supply system,aiming to achieve greater energy conservation and renewable energy utilization.Firstly,the thesis establishes the thermodynamic model of the solar energy and geothermal energy subsystem,and verifies it.The geothermal water subsystem uses the heat pipe oil-gas heat exchanger to recycle the geothermal water waste heat to produce the building hot water.It realizes the cascade utilization of energy and realizes energy saving.Secondly,the control variable method is used to analyze the main factors affecting the thermodynamic performance of the system such as atmospheric temperature,geothermal water temperature and flow rate and collector outlet temperature,and optimize the parameters of geothermal subsystem and combined energy supply system.Taking an office building in Lhasa,Tibet as an example,based on the first and second laws of thermodynamics,the time-dependent thermoelectric load of the solar geothermal energy combined energy supply system on a typical day was analyzed,and the thermal performance of the system under different load conditions was obtained.Thirdly,with the maximum output power and maximum thermal cycle efficiency as the objective function,the main parameters such as the collector outlet temperature,the collector heat carrier flow rate and the expansion vessel separation pressure are optimized.Finally,based on the economic theory of exergoeconomic and fuel-product-loss,the enthalpy efficiency,enthalpy loss rate and unit exergoeconomic cost of various components of the system under design conditions are explored,and the unit exergoeconomic cost of electricity under design conditions is obtained.And through the analysis of environmental protection and energy conservation of the combined energy supply system,the results show that the unit cost of the combined energy supply system is better than that of the separate geothermal system;the combined energy supply system has a greater advantage than the traditional fossil energy system.