Research On Performance Of Reversibly Used Cooling Tower (RUCT) Using Different Aqueous Solutions

A new type of air conditioning system, named as spring solution heat pump system presents itself recently. It uses heat pump, cooling&heating tower and ancillary equipment necessary as cold and heat source of constructions. In heating condition, appropriate solution is selected as circulation medium between the tower and the evaporator of heat pump in this system, which can absorb heat energy from ambient air in the tower. In cooling condition, solution is replaced with water, and the system is similar with tranditional ones which is equipped with water chilling unit and cooling tower. Compared with other conventional forms of air-conditioning systems, the spring solution heat pump system can satisfy both the need of heating and cooling of the building. And the advantage of it is self evident. Because it can run steadily, is more efficient in equipment using, has longer life-span, has adaptability to new surroundings, has higher COP or EER coefficient and cost lower in initial investment.However, air-conditioning system that includes a cooling&heating tower which is used for heating and cooling is currently in the initial stage of operation. So some of its technology is also being improved. When providing heat for the air-conditioning system in winter, the tower can be named as reversibly used cooling tower (RUCT). This paper present the research and analysis about the different running performance and initial investment of the system if using electrically operated valve between the liquid storage tank and the circular pipeline of the solution or not, or using different types of solute (LiCl and CaCl₂).In this paper, first, field experiments and theoretical analysis are combined to analyse the heat and mass transfer process between the solution and the ambient air when they contact directly in the RUCT, and a mathematical model of the heat and mass transfer process is established based on it. Second, in the winter, a reversibly used cooling tower heating system using heat pump (RUCTHPS) was installed in a test office building, which is located in Changsha, Hunan province. This running of the system lasted for a whole month, and all the necessary experimental data collected from the system during this period were used to validate and modify the mathematical model established previously to ensure the accuracy and applicability of the model. Third, program of the model is made by using programming software in quasi-static process, so that it could be used to calculate the mass transfer coefficient between the solution and the ambient air in the RUCT under different condition if using electrically operated valve between the liquid storage tank and the circulation pipeline of the solution or not, or using different types of solute (LiCl and CaCl₂). So that the condensation process in the RUCT and the freezing point of the solution could be simulated in every hour of the month.Finally, condensation of water, cost and safe operation of the system could be used to evaluate the advantages and disadvantages if using electrically operated valve between the liquid storage tank and the circulation pipeline of the solution or not, or using different types of solute (LiCl and CaCl₂). So that, in winter the most suitable type of solution and equipment configuration can be chosen for the RUCTHPS in Changsha.