Research On Regional Air Conditioning Cooling Source And Its Construction By Using The Cooling Capacity Of Seawater

At present, the energy-saving and the environmental protection issues have become two important problems concerned all over the world. Large-scale regional energy-saving air-conditioning system for district heating and cooling could be established by transferring the chilled water carrying cooling capacity of seawater to the cities nearby through underground aquifer, which will make full use of environmental-friendly cooling capacity of seawater on the aim of softening power shortage, exploiting new energy source (cooling capacity of seawater) and protecting ecological environment.In this thesis, a new technology of the regional air-conditioning system was put forward, in which the cooling capacity of seawater was used as a new kind of cooling source. According to the appropriate hydro-geological structure with good permeability and water bearing ability, which is also insulated from the open air, the chilled water was injected excessively into underground aquifer through injecting wells. Basing on the effect of pressure difference caused by interaction of the natural hydraulic gradient and the artificial one, the chilled water mixed with groundwater through the movement of fluid-flowing, heat-transferring and mass-exchanging was taken out by pump wells with large-flowing and high-lifting. As a result, the mixed chilled water could be used for air-conditioners in refrigeration consumption areas. In this thesis, the characteristics of flow movement, heat exchange and salinity change concerning chilled water transferring in porous media were mainly studied.Firstly, the flowing model of chilled water on the condition of forced flow was created. The injecting water volume and the geological parameters of underground aquifer, which have effect on the flow of chilled water, were studied. Secondly, the coolant transportation model combined with the seepage flow process was simplified appropriately and assumed according to realistic condition. Applying two-step calculation methods, control volume method (CVM) and alternating direction implicit method (ADI), the numerical simulation variations of heat during the migration process was analyzed. On the other hand, the influence of the thermal dispersion coefficient, the rock heat capacity and the hydraulic conductivity were predicted. Thirdly, concerning the salinity difference between the initial water located in aquifer and injected chilled water, the finite element method was used to simulate the two-dimension solute transport model, which combined the flow movement with the hydrodynamic dispersion. Besides, the molecular diffusion coefficient and the hydraulic conductivity on the salinity changing process were investigated. The results indicated that the temperature and the salinity of groundwater could be decreased effectively. The chilled water injected excessively into underground aquifer through large-flowing and high-lifting pumping wells could control the land subsidence effectively so that the subsided land would lift to a certain extent. Finally, this technology of transferring the chilled water carrying cooling capacity of the seawater through underground aquifer was proved to comply with sustainable development in views of energy utilization and geological disaster prevention.The conception of making chilled water for large-scale regional energy-saving air-conditioning system by exchanging heat with the seawater and using the underground aquifer as a natural passage was proved feasible. Aquifer is always used for thermal energy storage but it would play a different role in this brand-new technology. Generally speaking, the regional air-conditioning scheme is proved economic, effective and energy-saving, and also accordant with sustainable development and circular economic mode.