| Heat source tower heat pump emerges as a new building heat-source program and is developed rapidly. In summer, heat source tower works as the function of cooling tower, releasing heat into ambient. While in heating season, heat-source tower is used to extract heat from ambient air for the supply of low-grade heat in a heat pump system, where the heat and mass transfer process occurs between chilled solution and air. Moisture is transferred from air-to solution in tower when the vapor pressure on air side is higher than the vapor pressure on solution side, which causing dilution of solution and rise of its freezing point. The moisture condensation characteristics have a great impact on operation safety and system efficiency of heat-source tower heat pump system. So the regeneration of solution concentration is needed for a sustainable and reliable operation of heat-source heat pump. This thesis mainly presents theoretical, numerical simulation and experimental study on the solution regeneration process for heat-source tower under winter condition, and proposes a kind of solution regeneration method based on low pressure boiling. This paper provides a guidance in solution regeneration for heat source tower heat pump and liquid desiccant system.In view of the characteristics that the liquid boiling point will decrease with the decreasing pressure, a regeneration method based on low pressure boiling is putted forward. The solution regeneration can be achieved by using strong vaporization characteristics of boiling liquid to discharge water came from air in the solution.From the perspective of the solution equilibrium, conditions of boiling solution generating bubble and condensed vapor forming droplets are given a detailed description. Combined with vapor-liquid equilibrium theory of glycol solution, content of glycol in the gas and liquid phase is analyzed theoretically. Simultaneously the regeneration process based on low pressure boiling is described in detail theoretically with Enthalpy-concentration diagram of glycol solution.A solution regeneration system based on low pressure boiling is designed and improved after doing several experiments validating the feasibility of the low pressure boiling solution regeneration. The solution regeneration process based on the low pressure boiling happened in the solution regeneration system is described. And the results shows that the glycol solution is appropriate for low pressure boiling regeneration rationality and economically. The mathematical model of solution regeneration based on the low pressure boiling is established to do the further research.The major equipment of the solution regeneration system such as evaporator, condenser and vacuum pumps is designed and selected in this paper. Simulation and experimental work have been conducted to investigate the change rules of the individual parameters during the solution regeneration process. The effects of hot water inlet temperature, cooling water inlet temperature and the initial concentration of the solution on the solution regeneration process have been investigated deeply while verifying the accuracy of the mathematical model. The results show that the mathematical model has great prediction precision, and that effect of hot water inlet temperature on the solution regeneration process is most remarkable. |
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