【作者】 范亚明；

【导师】 付祥钊；

【作者基本信息】 重庆大学 ， 供热、供燃气、通风与空调工程， 2009， 博士

【摘要】 目前利用湖库塘水体的水源热泵越来越多,但有关湖库塘水源热泵的理论基础研究却较少,工程实践中,往往根据某些时间的湖库塘水体自然状态的温度,确定方案决策和技术计划与运行,常常造成失误。本文认为无论从工程实际还是理论上,都必须考虑取排水作用下的湖库塘水温分布,以及取排水方式对热泵系统能效和能耗的影响。为了该项技术节能潜力的发挥以及推广应用,本文受国家“十五”攻关课题( JA07149)和“十一五”科技支撑计划项目(2006BAJ01A06-3)资助,针对湖库塘开式水源热泵系统的取排水方式,研究湖库塘水温变化规律、供冷能力,以及系统性能问题,取得了一些初步成果,主要归纳如下:(1)本文确定的修正修正湍流prantl的k-ε两方程垂向和横向二维水温模型,能较为真实反映取排水作用下的湖库塘水温变化规律,可以作为实际工程方案决策、技术设计和运行调试的分析工具。(2)湖库塘在夏、秋季节出现热分层现象,表层为温水层,底部为冷水层,中间为温跃层。湖库塘的主要热特性之一是跨季节蓄冷能力比蓄热能力强,本文以研究湖库塘的跨季节蓄冷性能为主,同时考虑到湖库塘的热交换主要以水面为主,分析了水面热交换的影响因素。本文通过二维水温模拟分析湖库塘水体换热状况和相应的调控措施对湖库塘全年自然水温变化的影响,发现风力影响最显著、太阳辐射影响次之,通过对风力作用和太阳辐射的调控,可以明显提高湖库塘的跨季节蓄冷能力。(3)通过分析发现取排水方式对湖库塘的供冷能力有较大影响,本文借鉴分层水蓄冷方式,提出利用稳流器装置底部取水、同温层排水的理想状态,并且通过理想取水温度模型对影响理想供冷能力的因素进行了分析。结果表明:增大取排水温差、增加水深、同温层排水方式、较差的水质和冬季寒冷的气候都有利于增加湖库塘的理想供冷能力,其中水深、排水位置、水质和取排水温差影响较显著,在相同的气候分区内,气候影响不显著。以上分析为最大发掘热分层湖库塘的供冷能力提供了技术方向。(4)建立和验证湖库塘重叠式取排水二维模型,分析影响重叠式取水温差的因素,通过分析发现:当采用增加取排水口高度的措施来改善取水温升现象时,必须保证水深与排水口高度之比H /h小于临界值9,才能起到经济有限地降低取水温升的作用,否则不仅增加管道初投资,而且产生相反的效果;在实际工程中取排水口高差Δz /h不一定最大就好,超过(Δz / h)CV=6后,排水对取水的影响的效果不太明显,如果追求最大取给排水距离Δz值,采用底部取水不仅工程费用增加,而且会扰动底部水层,不利于保持湖库塘的热分层现象,对于降低取水温度的实际意义并不大;此外,取排水温差影响实际状态接近理想取排水状态的程度,取排水温差越大,( )Fr CV越小,越接近理想取排水状态,实际中取排水温差应大于取排水温差临界值( )ΔTCV=10或排水Fr小于临界( )Fr CV=1.3。在实际工程中如不能保证合适的取排水口间距Δz /h的值,不推荐使用重叠式取排水方式。从而为实际取排水设计提供了参考依据。(5)通过建立的湖库塘开式水源热泵系统模型对影响热泵系统性能的影响因素进行了分析,结果表明:在温水层取排水时,气候对热泵性能的影响较为显著,水质、水深和取水位置的影响次之,运行方式和热泵负荷的影响较小。其中,冬季温和的气候、增大水深、较差的水质、越深的取水位置、间歇运行方式和较小的热泵负荷有利于热泵性能的提高。有助于在实际工程中提高湖库塘水源热泵系统性能。(6)提出一种简单可行的湖库塘开式水源热泵系统全年能耗分析方法,然后以小型办公建筑为实例,进行具体的全年能耗分析,最后与空气源热泵的能耗相对比,分析结果表明:湖库塘开式水源热泵系统的性能更高、更稳定;室外循环水泵能耗对湖库塘开式水源热泵系统的能耗存在较大的影响,应该在实际工程应用中采取措施降低循环水泵能耗。更多还原

【Abstract】 Due to lack of the fundamental research, the utilization of lake-source heat pump system is still on the demonstration stage. And, it is difficult to use widely the energy-efficeint technology of lake-source heat pump system. In this paper, under the fund of the Tenth Five-year and the Eleven Five-year national scientific and technological project, the study of the thermal performance of lake used with open-loop water source heat pump is systematically analyzed and performance of system is proposed. Meanwhile, the factors influencing the performance of lake and heat pump system are investigated. The results are presented as follows:(1) A 2-D numercial model based on the Navier–Stokes equations is used to simulate the temperature of long narrow stratified lake without inflow and outflow. According to the test data of water pond in Chendu, the accuracy of k-εstandard model and prantl modified k-εmodel are compared. The results show that prantl modified k-εmodel can accurately simulate the thermal stratification of the water.(2) Because thermal characteristic of the lake shows that it has ability to store cool water easily than heat water over seasons, the emphasis is put on the ability of cool storage of the lake. The temperature of the lake under three different conditions from spring to summer is simulated with 2-D temperature model. The analysis shows that the shielding method of solar radiation and wind over water surface and bad water quality make significant influence on the promotion of cool storage of the lake.(3) In order to maximize use of low temperature water under the stratified lake, it is assumed that vertical location of outtake diffuser changes in time in such a way to interact with the ambient water temperature most closely matches the inlet water temperature. The lake temperature change is predicted when specific loads are applied, then ideal cooling capacity of lake when used as heat sink is determined. The factors influencing the ideal cooling capacity of lake are investigated. It is showed that: (ⅰ) Increase of temperature between inflow and outflow is beneficial to increase of cooling capacity of lake. (ⅱ) Climate exerts some effect on the cooling capacity of lake. (ⅲ) water depth has significant influence on unstratified lake. (ⅳ) Inflow is discharged according to same temperature of ambient water can promote considerably the cooling capacity. (ⅴ) Water quality influences significantly on cooling capacity.(4) A 2-D temperature model with eclipse form intake-outlet method is established to analyze the factors influencing the intake water temperature. The results show that: (ⅰ) Increase of outlet height can decrease the change of intake water temperature, only under the condition that the ratio of lake depth to width of outlet must be more than critical value. (ⅱ) the greater distance of intake and outlet, the smaller change of the intake temperature. However, maximum ratio doesn’t mean the better effect. So, it is suitable to adopt the critical value. (ⅲ) the greater Fr, the smaller change of intake water temperature. (ⅳ) By comparing the inlet temperature of march-past method and eclipse form, the superiority of the latter only exist with suitable distance of intake and outlet.(5) Open-loop lake source heat pump system model is established to predict different factors affecting the performance of system. The analysis is proposed that: (ⅰ) Winter weather has more significant influence on system performance than summer weather. (ⅱ) Water depth has unimportant affect on it. (ⅲ) Water quality exert some influence on it. (ⅳ) the deeper outlet place, the greater performance efficiency. (ⅴ) Operating model has some affect on performance.(6) An annual energy consumption calculation model of open-loop lake-source heat pump is established. And the comparison of annual energy use of lake-source heat pump system with air source heat pump system is presented. SEER of lake-source heat pump system in winter and summer are higher than air-source heat pump system. It prove that open loop lake source heat pump is more energy efficient than air-source heat pump. However, SEER of open-loop water source heat pump systems used with lake decrease in winter and summer included by water pump. So, it is necessary to decrease the energy consumption of water pump for higher energy efficiency of open-loop lake source heat pump system.更多还原