直接式原生污水源热泵系统的防堵技术及换热特性研究

1、博士学位论文直接式原生污水源热泵系统的防堵技术及换热特性研究CLOG-PROOF TECHNIQUE AND HEATEXCHANGE CHARACTERISTIC RESEARCHOF THE DIRECT UNTREATED SEWAGESOURCE HEAT PUMP SYSTEM庄兆意哈尔滨工业大学2012年7月国内图书分类号：X703.3 学校代码：10213 国际图书分类号：628.2 密级：公开工学博士学位论文直接式原生污水源热泵系统的防堵技术及换热特性研究博 士 研究生：庄兆意导 师：孙德兴 教授申 请 学 位：工学博士学 科、专 业：供热、供燃气、通风及空调工程 所 在 单

2、位：市政环境工程学院答 辩 日 期：2012年7月授予学位单位：哈尔滨工业大学Classified Index：X703.3U.D.C. ：628.2Dissertation for the Doctoral Degree in EngineeringCLOG-PROOF TECHNIQUE AND HEATEXCHANGE CHARACTERISTIC RESEARCHOF THE DIRECT UNTREATED SEWAGESOURCE HEAT PUMP SYSTEMCandidate ：Zhuang Zhaoyi Supervisor ： Prof. Sun DexingAcadem

3、ic Degree Applied for ：Doctor of Engineering Specialty ： Heating, Gas Supplying, Ventilation& Air-conditioning EngineeringAffiliation ： School of Municipal andEnvironmental EngineeringDate of Defence：July,2012 Degree-Conferring-Institution ：Harbin Institute of Technology摘 要摘 要城市污水中蕴含有丰富的低位热能，将其作

4、为热泵的冷热源为建筑供热空调具有巨大的开发利用价值。城市污水的水质极为恶劣。其热工与流动性能与清水有很大不同。污水处理厂中的二级出水（排放水）接近清水的水质，但由于污水处理厂多位于远离城市建筑群的郊区，因此真正具有巨大开发利用价值的是遍布城区污水渠中的原生污水。传统的热泵空调机组对水质有严格的要求。因此目前在利用原生污水的热泵系统中多为避免污水直接进热泵系统的蒸发器或冷凝器而设置一个中间换热的措施，即所谓“间接式系统”，这种间接式系统不仅要增加中间换热设备而且要增加系统的火用损失，故开发污水直接进机组的热泵系统，即所谓“直接式系统”，从污水源热泵技术产生以来就对学术与工程界具有巨大的诱惑力。直

5、接式污水源热泵系统由于污水水质的特殊性，必须解决以下关键问题：（1）对过滤和防阻塞的效率和可靠性提出了更高的要求；（2）必须认清污水的流动、换热以及污垢热阻的特性与规律；（3）必须认清污水蒸发器、冷凝器的换热特性；（4）直接式热泵系统两换热器的合理匹配与性能。本文对此主要进行了下述研究工作：直接式污水源热泵系统能够长时间连续安全换热，首要前提是必须保证大尺度污物不进入机组的换热器中。针对已在间接式污水源热泵系统中普遍应用的污水防阻设备，通过工程实践和测试，总结发现：（1）丝状纤维类污物是阻塞滤面的最大诱因；（2）参考传统做法，仅靠过滤孔直径难以衡量防阻机滤面的过滤与再生能力；（3）不可避免的存

6、在内漏混水的情况。论文建立了以缠绕长度、反冲效率、内漏率、换热保证率为核心的，包括滤孔直径、反冲面积比、转速、阻力等在内的防阻机设计指标体系，并通过工程测试确定了最佳的缠绕长度、反冲面积比和清洁周期，为防阻的科学合理设计及工程选用提供了合理依据。设计并在哈尔滨太平污水处理厂搭建了城市原生污水性能研究实验台，实验研究了城市原生污水在各种管材圆管内紊流流动时的污垢热阻特性，流动阻力特性及对流换热特性。通过大量实验数据总结出各种常用换热管内污垢热阻增长规律，以及污垢热阻稳定值与管内污水流速的函数关系、污水紊流流动的阻力系数计算式及换热准则关联式。实验表明污垢增长模型为时间的渐进型函哈尔滨工业大学工学

7、博士学位论文数，在同管径同流速下污水的流动阻力系数约为清水的1.081.12倍，对流换热系数约为清水的0.750.82倍。这些基础数据与经验公式为污水源热泵系统的换热设备研发、系统设计等提供了较为可靠的依据。依据污水流动、换热及污垢热阻特性、换热管污水侧难以强化换热的特点，建立了污水蒸发器与冷凝器的分布参数模型，编制了仿真程序并进行了大量的数值研究，给出了污水蒸发器和冷凝器的传热系数范围，以及污水温度和流量变化对换热器换热特性的影响规律。发现与常规水源热泵的两换热器相比，污水蒸发器与冷凝器内污水以四流程为宜，冷凝器内蒸汽过热段所占比例较大，过热对冷凝换热影响明显，为系统换热器设计以及系统性能分

8、析打下基础。通过直接式污水源热泵系统建模与数值仿真，给出了直接式系统的效能范围，以及污水温度对效能的影响规律。规定了污水源热泵机组的标准设计工况，并深入分析了污水蒸发器、冷凝器面积匹配比与机组制热量、制冷量、出力比之间的关系。由于污水源热泵机组具有更大的适宜面积比范围和出力比范围，提出不同地区采取不同面积比进行热泵机组设计的理念。最后给出了非标准工况下热泵机组的特性以及设计与选型原则。本文通过研究主要解决了直接式污水源热泵系统所面临的防堵塞可靠性、污水流动与换热计算方法、污水蒸发器与冷凝器的换热特性、机组换热器匹配等问题，为直接式污水源热泵技术的发展奠定了一定的理论基础。关键词：原生污水；直接

9、式系统；热泵；防堵塞性能；匹配AbstractAbstractMunicipal sewage contains so abundant low level heat that it will mean a huge value for development and utilization when used as a cold and heat source of heat pumps for heating and air-conditioning system of buildings.The water quality of municipal sewage is extremely

10、 poor and the thermal and flow properties of it are quite different from those of clear water. In contrast, the water quality of secondary effluent from sewage treatment plants (discharge water is close to that of clear water. However, sewage treatment plants are mostly located in suburbs far away f

11、rom the city buildings, so it is exactly untreated sewage all over the city sewers that will mean the huge value for development and utilization.Traditional heat pump air conditioning units have strict requirements on water quality. Therefore, measures of intermediate heat-transfer are often taken i

12、n the present heat pump system based on untreated wastewater to avoid sewage flowing directly into the evaporator or condenser of the system which is the so-called "indirect system" and not only introduces extra intermediate heat-transfer devices but also increases system energy loss. So t

13、he development of heat pump system namely the so-called "direct system" allowing sewage to enter the units directly shows a great allure on the academic and engineering fields from the origin of the technology of sewage-source heat pumps.Considering the specialty of the water quality of se

14、wage, direct sewage-source heat pump system must solve the following key problems. Firstly, higher requirement is needed for efficiency and reliability of filtering and anti-blocking. Secondly, the feature and discipline of flow, heat-transfer and fouling heat resistance of sewage must be recognized

15、. Thirdly, the heat-transfer performance of sewage evaporator and condenser should be recognized as well. At last, reasonable match and performance of the two machines of direct heat system need to be taken into consideration. This paper mainly introduces the research work on the mentioned technique

16、s as follows.The primary precondition of safe and enduring heat-transfer for direct sewage source heat pump set is to guarantee that large-scale contaminant of all shapes cannot enter the heat exchanger of the set. Corresponding to the universally哈尔滨工业大学工学博士学位论文employed sewage clog-proof machine in

17、indirect sewage source heat pump systems, we have performed engineering practice and test, according to which we make following conclusions. Firstly, filamentous contaminant is the main incentive of blocking filter surface. Secondly, referring to the traditional method, it is tough to measure the fi

18、ltration and regeneration ability of the clog-proof machines filter surface only with the diameter of filter hole given. Thirdly, the condition of internal leakage mixing water exists inevitably. The paper establishes a design index system of clog-proof machine including filter pore diameter, recoil

19、 area ratio, rotating speed, resistance and so on, and winding length, recoil efficiency, internal leakage rate and heat-transfer guaranteed rate are the core of the index system. The paper also defines the optimal filter pore size, recoil square ratio and cleaning period of the clog-proof device by

20、 engineering tests, all three of which provide reasonable foundation for scientific and rational design of clog-proof device for engineering application.An experiment table focusing on city untreated sewage properties research has been designed and constructed in Harbin Taiping sewage treatment plan

21、t as to be mentioned in the paper. Experiments have been executed on the fouling heat resistance performance, flow resistance characteristics and flow and heat-transfer characteristics of urban untreated sewage turbulent flow in a variety of pipes. Through considerable experimental statistics, we ca

22、n reach such conclusions as fouling heat resistance growth disciplines for kinds of common heat-transfer pipes, the function between the stable value of fouling thermal resistance and the sewage flow rate in the pipe, an expression for resistance coefficient of sewage turbulent flow and finally a he

23、at transfer correlation formula. The experiment results demonstrate fouling growth model as a progressive function of time. Specifically, experiments verify that with same pipe diameter and flow rate, the flow resistance coefficient of wastewater is approximately 1.081.12 times that of clear water,

24、whereas the convective heat transfer coefficient is about 7582 percent of that of clear water. These fundamental statistics and empirical formulas provide more reliable basis for heat-transfer device development and system design of sewage source heat pump systems.Based on the sewage flow, heat tran

25、sfer and fouling resistance properties and the characteristic of difficulty in heat transfer enhancement at the sewage side of heat transfer tube, a distributed parameter model of the sewage evaporator andAbstractcondenser is established, and simulation programs have been developed and employed to d

26、o amounts of numerical study which obtains the scope of sewage evaporator and condenser heat transfer coefficients and the law of influence exerted by sewage temperature and flow changes on their heat transfer properties. It is also found that compared with the two machines of the conventional heat

27、pump, the sewage evaporator and condenser have following prominent characteristics. Four processes are appropriate for wastewater inside the machines, and steam superheating segment in condenser takes up a great proportion. In addition, the impact of superheating on condensation heat transfer is sig

28、nificant. All the achievements lay the foundation for system evaporator and condenser design and system performance analysis.Through direct sewage source heat pump system modeling and numerical simulation, the efficiency range of direct system and the law of sewage temperatures influence on performa

29、nce are given. Then we set the standard designed working condition of sewage source heat pump units and do deep analysis on the relationship between the matching ratio of sewage evaporator and condenser area and heat output, cooling capacity and power output of the units. For the greater range of su

30、itable area radio and power output radio of sewage source heat pump unit, we put forward the concept that different area ratio will be adopted while designing heat pump units in different regions. Finally the characteristics of heat pump units and principles for design and selection are introduced u

31、nder non-standard working conditions.By researching, this paper has mainly solved problems faced by direct sewage source heat pump system such as the clog-proof reliability, sewage flow and heat transfer calculation method, heat transfer properties of sewage evaporator and condenser and the matching

32、 of the two devices, all of which lay theoretical foundation for the development of direct sewage source heat pump system.Keywords : untreated sewage, direct system, heat pump, clog-proof, matching哈尔滨工业大学工学博士学位论文符号表A 面积 e t 蒸发温度 f C挂壁系数c t 冷凝温度 COP 性能系数T 热力学温度 c换热管单元面积造价 U 热流密度 p c定压比热 u 管内流速 d 管段直径

33、 m u 断面平均流速 D圆筒直径 f u网孔滤速 E相对误差 V 流量EER 能效比 th V 压缩机理论排气量 F 面积z 高差 f 沿程阻力系数 希腊字母G 质量流速 负荷比 H水泵扬程 v 比容h对流换热系数 机组出力比f h 沿程阻力损失 气相空隙率 g重力加速度 z 管束修正系数 k 工质绝热指数 f 强化管修正系数 s k 管壁绝对粗糙度 导热系数 K 总传热系数 动力粘度 L长度 制热制冷量 M液体的分子量 局部阻力系数 m 质量流量 网孔堵塞厚度 N功率 挂壁概率 Nu努谢尔特数 * 时间常数， NTU 传热单元数 液体的密度 n 流动系数 稠度系数P 压力 滤网的拉应力 P

34、r Prantl 数 运动粘度 P 压差 面积比Q换热量 工程设计负荷 ij Q 单元内热负荷 下角标f Q过水流量 f 污垢侧 w Q 电加热功率 c 清洁侧 f R污垢热阻 p 污染状态 *f R污垢渐近热阻值h制热符号表Re Reynolds 数 L 冷流体；损失 r 管半径 s 夏季；壳程 S 孔板面积比 t 管程 w S 反冲区的局部阻抗 1 入口 f S 过滤区的局部阻抗 2 出口 HE S 换热器及管路的阻抗 in 进口 m t 平均对数温差out 出口 ' t 管壁与污水进口处温差 w 冬季 '' t 管壁与污水出口处温差 r 制冷剂 , s i t污水

35、进口温度 d 标况下 , s o t 污水出口温度e 蒸发 , w i t 污水进口处管外壁温度 c 冷凝 , w o t污水出口处管外壁温度q清水哈尔滨工业大学工学博士学位论文目 录摘 要. I Abstract. III 符号表. VI第1章 绪 论.11.1 课题背景及研究意义.11.1.1 能源与环境问题.11.1.2 污水源热泵技术的发展.21.1.3 污水源热泵推广应用的制约因素.41.1.4 课题的提出及研究意义.51.2 国内外研究现状及分析.61.2.1 工程应用.61.2.2 污水源热泵技术研究.91.2.3 研究现状分析总结.191.3 本文的主要研究内容.19第2章 直

36、接式污水源热泵系统的防堵技术研究.212.1 引言.212.2 污水防阻机的过滤与再生数学模型.212.3 污水防阻机工程实践问题总结与分析.252.3.1 滤面的堵塞与破坏现象.252.3.2 滤面堵塞与破坏分析.262.4 滤孔缠绕长度及其对反冲效率的影响.292.5 防阻机混水特性及对换热的影响.312.5.1 防阻机混水的种类和必然性.322.5.2 混水率与反冲比的数学模型.322.5.3 混水影响与换热保证率.352.5.4 考虑混水后的系统设计.382.6 滤面设计与评价指标.392.7 防阻机与换热器的清理维护措施.412.8 本章小结.42第3章 城市原生污水流动与换热特性实验.44目 录3.1 引言.443.2 实验原理与方法.443.2.1 污垢热阻测试原理与方法.443.2.2 流动阻力测试原理与方法.453.2.3 对流换热测试原理与方法.463.3 实验平台设计与实验方案.473.4 实验测试的参数及方法.503.5 实验结果与分析.533.5.1 污垢热阻特性.533.5.2 流动阻力特性.583.5.3 紊流换热特性.603.6 实验系统误差分析.633.6.1 污垢热阻的测试误差.643.6.2 沿程阻力系数的