【作者】 王芳；

【导师】 郑茂余；

【作者基本信息】 哈尔滨工业大学 ， 供热、供暖气、通风及空调工程， 2009， 博士

【摘要】 太阳能-土壤源热泵(Solar-Ground Source Heat Pump, SGSHP)因其利用太阳辐射热和可再生的浅层土壤热,被认为是21世纪一项最具有发展前途的、具有节能和环保意义的制冷空调技术。该系统是以太阳能作为主要热源的热泵系统。制约太阳能-土壤源热泵技术发展的因素很多,其中,太阳能的蓄存、地下埋管换热器换热和土壤热平衡问题一直是太阳能土壤源热泵技术的研究关键。本文在总结了国内外太阳能土壤源热泵技术与蓄能技术的基础上,将二者有机地结合在一起,设计了太阳能季节性土壤蓄热供暖(冷)系统(Heating (Cooling) System of Solar Seasonal Soil Storage),该系统主要是由太阳能集热系统、土壤蓄热系统、热泵机组、地板辐射末端装置组成。本文以该系统的地下埋管换热器作为研究对象,主要从以下几个方面进行了研究:首先,利用有限单元法建立了土壤换热器三维数理模型,模拟了系统连续运行两年土壤温度场的变化及恢复情况。运行结束,土壤温度比初始值高了将近1℃。该系统特别适合用于严寒地区,冬季:太阳能做为主要热源,土壤源热泵做为辅助热源;夏季:土壤换热器直接供冷。土壤一年三季(春、夏和秋)进行长期蓄热,这样不仅保持了土壤的热平衡,还为下一个冬季更好地供暖提供了保证。其次,在所建立的数理模型基础上,本文首先模拟了单根U型管换热器的运行特性,研究了以年为周期,系统运行两年的不同深度(5m、30m和50m)土壤的温度变化情况、不同运行工况下U型管换热器对周围土壤温度的影响、不同土壤热物性和不同U型管管材对周围土壤温度的影响。再次,又模拟了多根U型管换热器的运行特性,从土壤热物性、埋管管材、埋管间距及埋管排列方式四个方面分析了影响土壤与埋管换热器之间的换热效果。其中,埋管管材对长期运行的太阳能季节性土壤蓄热供暖(冷)系统影响不是很大。在选择管材类型时,可从经济上考虑,本文选择了价格低廉的普通聚乙烯管材。另外,对换热影响最大的是埋管排列方式。四种排列方式中圆形的排列方式换热器换热能力最强,其次是多边形和正方形排列方式,最差的为矩形排列。换热能力强的排列方式,冬季换热器日取热量大,出水温度高;但夏季出水温度过低,不利于地板辐射供冷。因此,在选择换热器排列方式时,本文采用的是矩形排列,虽然冬季换热效果没有前三种好,但完全可以满足供暖要求,夏季又符合地板辐射供冷水温的要求。最后,为了考察太阳能季节性土壤蓄热供暖(冷)系统的运行特性,同时验证本文所建数学模型的正确性,在哈尔滨市松北区建立了太阳能季节性土壤蓄热供暖(冷)实验系统示范工程。本实验系统是把太阳能热泵、土壤蓄热及地板辐射系统有机的结合在一起的供暖(冷)空调系统,于2007年11月开始运行。实验测得:供暖中期平均供暖性能系数为5.01,供暖末期供暖性能系数可达13.02。在相同(或近似)的条件下,通过比较实验值和模拟值吻合较好,验证了本文建立的数学模型的正确性和可靠性。太阳能季节性土壤蓄热供暖(冷)系统是一种新型节能、环保的供暖(冷)系统,由于经济性等原因,目前该系统在实际中还得不到广泛的应用,但是随着常规能源的日益枯竭、能源价格的逐渐上涨、环保压力的不断增加,同时还由于太阳能供暖、空调技术的不断完善,太阳能季节性土壤蓄热供暖(冷)系统将成为一种非常有竞争力的供暖(冷)方式。本文的工作可以为今后太阳能季节性土壤蓄热供暖(冷)系统的应用提供理论基础和技术支持。更多还原

【Abstract】 Solar with ground source heat pump (SGSHP) is taken as an air conditioning technique which has the greatest future, energy saving and environmental protection in the 21st century, since it utilizes solar radiant and renewable underground heat. Solar energy is regarded as the main heat source of the heat pump. The development of SGSHP is restricted by a lot of factors, and storage of solar energy, heat transfer of underground heat exchangers and heat balance of soil are three key points of research.Based on the researches done on the SGSHP and energy storage technology, a novel system combined the two systems was proposed and named as heating (cooling) system of solar seasonal soil storage. It consists of a solar energy collecting system, soil storage system, a heat pump unit, floor radiant terminal device. The main study object is underground heat exchanger. The research is based on the following aspects:First, three-dimensional numerical model of underground heat exchanger was established using finite element method. Simulation was done for observing soil temperature field variation and resumption and soil temperature was enhanced 1℃after two years running. The system is suitable in cold weather areas. Solar energy is the main heat source and ground source heat pump is the auxiliary heat source in winter; cooling can be extracted by underground heat exchangers directly in summer. Soil storage is a long period energy storage process that goes along in three seasons (spring, summer and autumn). It can not only maintain the balance of soil, but also supply the guarantee for heating of next winter.Second, based on the numerical model, operation characteristics of single U-type heat exchanger were simulated. Variation of temperature of different depths (5m, 30m, 50m), influence of different operation conditions on soil temperature, influence of soil properties and pipe materials on soil temperature were studied for two years’operation with period of year.Third, operation characteristics of muti U-type heat exchangers were simulated, too. Heat transfer effect between soil and heat exchangers was analyzed in four aspects: thermal physical properties of soil, material of pipes, and space of pipes and arrangement mode of pipes. Material of pipes has little influence on long period running solar storage soil storage system. It can be considered economically when choosing. Common PE plastic pipe has been chosen as the material in the system because of its low price.Forth, the most influential factor is arrangement mode of pipes. The best heat transfer ability is arrangement of circuit rotundity; the better ones are polygon and square arrangement; the worst one is rectangle one. Arrangement of strong heat transfer ability has large heat extraction per day of heat exchangers and high outlet water temperature in winter; meanwhile, it has low outlet water temperature in summer. It goes against floor radiant cooling. Rectangle arrangement has been used in the system. It can not get to the requirement of heating in winter though its heat transfer effect is the worst in four arrangement, but also accord with the demand of low temperature radiant floor cooling in summer.Last, demonstration engineering started to operate from Nov. 2007 which was established in Songbei district Harbin in order to research the operation characteristics of the solar seasonal soil storage heating (cooling) system which combined with solar heat pump, soil storage and floor radiant system together, and meanwhile, to validate the simulation results. Experimental test data: mean heating COP is 5.01 in middle heating period and 13.01 in end heating period. The results between the experimental measurements and simulations under the same (similar) conditions tally well, so that the numerical model was validated within acceptable accuracy and reliability.The novel heating (cooling) system of solar seasonal soil storage cannot be quite popular at present due to certain financial constrain. However, with energy sources decreasing, energy prices increasing and an awareness of the sustainable development increasing, it promises a bright future as an alternative means for heating (cooling) system. It is believed that the system could be popular with the development of the solar energy heating and air conditioning technologies. The study done in this thesis provides a fundamental and theoretical support for the further application of the system.更多还原