地源热泵系统的模拟与设计.docx

参考文献 摘要：总结了近年来地源热泵系统的模拟和设计方面的研究和进展。首先给出了地源热泵系统各部件建模方面的进展，包括竖直埋管地热换热器、单井循环系统以及在地源热泵混合系统中采用的几种辅助散热装置。其次，讨论现场测定深层岩土热物性的技术。第三，介绍竖直埋管地热换热器的设计方法。最后，给出在设计地源热泵系统中采用系统模拟的几个应用实例。关键词：热泵；地热换热器；热物性；混合系统；模型；设计；模拟1.简介从热力学的观点来看，在空调系统中利用地源热作为热源或者冷源是吸引人的。这是因为，从全年来看，其温度比环境干球或湿球温度更接近于室内（所需要）的温度。基于这个原因，地源热泵系统较之空气源热泵系统在高效率上更具有潜力。在实际情况中，源热泵系统由于没有设备暴露在外部的环境中,花在维修方面的费用是比较低的(Cane, et al. 1998).虽然已经有一些地源热泵系统技术在斯堪的那维亚半岛得到发展，但是其商业上的开发利用却是在美国做得最好。这是主要是因为在美国已经存在着一个很大的住宅空调系统市场。其系统由于有着较低的能耗和低运行费用已经证明吸引了很多业主。在美国很多地区用电峰值取决于空调用电量。 对于这个原因使得一些电力设备公司对这个系统很感兴趣,他们希望通过使用这样的系统来减少对电力的需求。一些小型商业机构和公共部门已经研究出这种技术的应用。地源热泵系统由于其较低的运行费用而吸引一些学校主管,并有越来越多的学校使用。在美国关于地源热泵技术实际应用的一些实例研究细节已经交给GHPC。在论文接下来的部分中我们首先会给出地源热泵系统各部件建模方面的进展，包括竖直埋管地热换热器、水源热泵、单井循环系统以及在地源热泵混合系统中采用的几种辅助散热装置。由于要设计地下换热器首先就要了解地热的属性，这篇论文的第二部分简要介绍了确定深层岩土热物性的模型，这种方法是由对测试孔温度反应的现场测试法引申而来的。在论文的第三部分，将会介绍一下用软件来设计竖直埋管地热换热器的方法。最后，给出在设计地源热泵系统中采用系统模拟的几个应用实例，其中包括混合 GSHP 系统和防冻GSHP系统的设计。2.GSHP系统模型构成GSHP系统一般由水源热泵和地下换热器组成，对于混合GSHP系统，还包括几种辅助散热装置。这些模拟的设备在下面被覆盖。2.1闭循环地下换热器闭循环双管系统可采用水平埋管或垂直埋管。垂直埋管系统由于其较高的换热效率而被人们较多的采用。这种类型的闭式循环换热器由一根根置入直径为75MM150MM钻孔的U型管组成。这些钻孔在置入U型管后用钻出来的土回填或者，更普遍，整个孔都用薄泥浆填塞。灌浆通常是避免地下水的污染而且使换热管道与完全接触以达大良好的换热效果。常用于系统埋管的是直径为22MM33MM的高密度聚乙烯管 (HDPE)。打孔深度一般在30M120M之间。两种模拟的复杂性很有意思。首先，测量地下换热器在单位时间内用户的最小输入的设计方法是可取的。其次，其能预测数小时内(或较短的时距)由于建筑物负荷的连续变化对地下换热器造成何影响的模拟模式也是也是可取的。这一理论允许对系统能量消耗和用电需求预测。因为两者的方法以被 Eskilson(1987) 发展的模型为基础在这论文中呈现了, Eskison 的方法将会首先被讨论,接着是对被 Yavuzturk 和 Spitler 发展的模拟模式的描述.(1999)2.1.1 Eskison 的研究方法Eskison (1987)针对地耦孔周围温度分布的确定问题的解决办法是采用逻辑分析和数学解析相结合的办法。对于初始条件和边界条件恒定的均匀土壤中的单个地耦孔的相关数值建立径向-轴向坐标，使用瞬态有限差分方程进行二维数值计算。像管壁和泥浆等个别钻孔要素的热容量是被忽略的。单个钻孔的温度场通过重叠来获得整个钻孔范围。整个钻孔范围的温度回应被转换到一组非线性的温度反馈因数,被称做G-函数。这个G-函数使得与某一时间内的特定热量输入相应引起的地耦孔壁的温度变化情况的计算成为可能。一经钻孔范围的反馈对阶梯热量的反馈用G-函数来表示, 任何的任意热反馈函数能被藉由在一系列的阶梯函数之上让热反馈/输出决定, 而且叠加对每个梯度函数的反馈。这一过程对于四个月的热反馈以图示的方法在图 1中表示。基本的热脉冲（从零到）是指历经整个过程4个月后的热量峰值，其值=。次级脉冲=- ，为3个月期间后的峰值。同理，=- 为两个月期末峰值，最后，=- 指一个月后的热量峰值。因此，任何时间地耦孔壁的温度都能够由这四个阶梯函数计算确定。从数学角度来看，在第n时期的末期，受位置因素影响的地耦孔壁的温度如下：其中:t =时间(s) H =孔井深度(m)k=岩土导热系数(W/(m.k) =孔井平均温度() =岩土稳态温度() Q=阶梯热反馈脉冲(W/m) = 孔径(m) i =时间梯度结束指数2.1.2仿真模型这里所说的仿真模型的大部分细节已经由Yavuzturk 和 Spitler所介绍。在本文中将会给出其简要的描述。这个模型的主要目标是应用在建筑能量分析上，这模型能够以每小时为单位来预测系统能量消耗。此模型籍由Eskilson理论完善而发展将在这里被讨论。Master的G-函数把预测频率增加至一小时数次。Eskilson 用来测定G-函数的数据模型不适用于短时距测量,采用另一种数据模型来测算一个地耦孔短时间内热反馈/输出脉冲的温度反应。对于短时间内的热脉冲来说，径向位置地耦孔内外的热转移比轴向位置的热转移影响大得多。由此，产生了一种二维径向定容模型。详情参见Yavuzturk,et al.(1999).2.2垂直圆形孔井垂直圆形孔井用于直接与岩土进行热交换。一种用来研究垂直圆形孔井性能的数据模型已经研发了，它由两部分组成：地耦孔构成的节点模型，附近地下水流动和岩土中热传递定容模型。这种模型的运用包括对地下水流动导致的热传递的明确处理(Rees,et al.2003) 。这种模型可以考察垂直圆形孔井的性能在使用中的影响和重要意义。其性能在以下几个参量中是最具敏感的：流量，地耦孔长度，岩土热传导率和水压传导率。2.3水源热泵Jin和Spitler(2002a)发明了一种参量估算水源热泵模型。这种模型对冷冻循环进行热力学分析，比热交换模型更简单，同时比冷冻循环压缩机模型更为精确。在第二篇论文（Jin,et al.2002b）中，对这一模型进行扩展，包括回旋式空气压缩机的子模型和使用防冻剂的步骤。制造厂商的目录数据中叙述了多变量优化算法估算出的模型中的各种参量。Jin(2002)详细叙述了多变量优化算法和估算出的参量。比起在此之前生产的方程-适宜类型模型，水源热泵模型更为精确。Jin(2002)还介绍了一种类似的水源热泵模型。2.4混合式GSHP系统的热量补偿地源热泵系统中地耦孔的成本是系统成本的重要部分，但它主要取决于当地地质状况。这种装置主要用于制冷建筑物中。在这种岩土的导热性差，钻孔条件简陋的地方，水源热泵系统的成本的比较昂贵。尽管如此，我们可以采取初次成本与能效折中的办法，缩小耦孔范围，在热泵水管内安装辅助散热装置。这样的系统称为混合型地源热泵系统。混合系统的水管中有各种不同类型的散热装置，比如冷却塔，带换热器的浅水池，液压加热面或者叫桥层。Chiasson(2002a)发明了浅水池模型，其原理是：由于闭循环换热器，需要在水层表面安装天然热传递装置的基础上安装对流换热装置。Chiasson(2000b)同时还发明了一种适用于液压加热面或者叫桥层的有限差分模型。这种模型甚至能够模仿积雪融化过程。以上这些模型使用试验性的辅助散热装置，在俄克拉荷马州大学得到认可。3.土壤热量特性的现场测定测量深层岩土的热传导性对于地源热泵系统来说至关重要。地耦孔的宽度长度主要取决于深层岩土的热物性。测定深层岩土的热传导性的传统方法是首先确定地耦孔周围岩土的类型。确定后，可以通过双管热泵系统设计手册中关于岩土类型的资料来测定其热传导性(EPRI1989)。据报道，岩土信息中的热传导性有更广泛的价值，因此能找到一种更精确地测定岩土热传导性的方法就更好了。深层岩土的热传导性不能直接测定，只能通过温热变换测定法来推断，还需利用一些地热传递模式，比如线形水源法(Ingersoll and Plass1948;Mogensen1983)或者柱形水源法(Carslaw and Jaeger1947)。有趣的是它们还有相反的用途由岩土的性能来测定其热物性，而不是由岩土的热物性来测定其性能。虽然线形水源法和柱形水源法可以反过来运用于测算岩土热传导性，但是仍然需要做一些简单假设，因为其影响结果是不易测定的。采用地耦孔详细数据模型，对地耦孔几何学和热流体，管道。泥浆以及岩土的热物性进行详细描述，可以减少简单假设造成的不确定因素。这样，对地热传导性就会有一个更精确的估算。岩土温度反应的分析步骤有两中基本类型：分析法(Witte,et al.2002)和参量估算法(Austin1998;Austin et al.2000;Shonder and Beck1999)。Witte et al(2002)用线形水源法和不确定分析法对岩土热传导性进行现场测试。Austinet al(2000)的参量估算法是用垂直钻孔的瞬态二维数据定容模式来测算一个已知的变时间的热流量输入的岩土温度反应。Nelder Mead 的单工运算法则被用来发掘岩土和泥浆热传导性的最有价值的用途，那就是把实验测量的温度反应和估算的温度反应之间的差值减小到最低限度。测量岩土热传导性的实验装置是由Eklof,Gehlin(1996)和Austin(1998)自主发明的。图5是Austin et al.(2000)发明的测试系统的示意图。实验装置放在一个可以拖动的拖车里。地耦孔安装被一个长达50 小时的试验证明是满意的。一个较短的试验时间是非常合人心意的, 而且可能是将来研究的主题。外文翻译： Summarized the recent years source heat pump system simulation and the design aspect research and the progress.First has given the source heat pump system various parts modelling aspect progress, including the vertical pipe installation geothermy heat interchanger, the single well circulatory system as well as several kind of assistance heat dissipating arrangement which uses in the place source heat pump mix system.Next, discusses the scene determination in-depth ground hot natural technology.Third, introduction vertical pipe installation geothermy heat interchanger design method.Finally, gives in the design source heat pump system uses the system simulation several application example. Key word: Heat pump; Geothermy heat interchanger; Hot nature; Mix system; Model; Design; Simulation1. synopses looked from thermodynamics viewpoint that, uses the source hot work in the air-conditioning system for the heat source or the heat sink is appealing.This is because, looked from the whole year, its temperature ratio environment dry bulb or the wet-bulb temperature approach (needs) in the room the temperature.Based on this reason, the source heat pump system has the potential compared with the air source heat pump system in the high efficiency.In actual situation, source heat pump system because does not have the equipment to expose in exterior environment, the flower in the service aspect expense is quite low (Cane, et al. 19982. Although already had some source heat pump system technology to obtain the development in the Scandinavian peninsula, but in its commercial development use was actually does well in US.This is mainly is because already has a very big housing air-conditioning system market in US.Because its system has the low energy consumption and the low operating cost already proved has attracted very many owners.Uses electricity the peak value in American very many areas to be decided by the air conditioning electricity consumption. Enables some power equipment company regarding this reason to be interested very much to this system, they hoped through uses such system to reduce for the electric power demand.Some small business organization and the public departments already studied this kind of technology the application.The source heat pump system attracts some school manager as a result of it low operating cost, and has the more and more many school use.Already gave GHPC in US about the place source heat pump technology practical application some example research detail.3. Meets down in the paper in the part we first can give the source heat pump system various parts modelling aspect progress, including the vertical pipe installation geothermy heat interchanger, the water source heat pump, the single well circulatory system as well as several kind of assistance heat dissipating arrangement which uses in the place source heat pump mix system.Because must design the underground heat interchanger first to have to understand the geothermy the attribute, this paper second part introduced briefly the determination in-depth ground hot natural model, this method is by to measured the test hole temperature responded the scene test method expands comes.In the paper third part, will be able to introduce will design the vertical pipe installation geothermy heat interchanger with the software the method.Finally, gives in the design source heat pump system uses the system simulation several application example, including mixes the GSHP system and the frostproof GSHP system design.4. The 2.GSHP system model constitutes the GSHP system generally is composed by the water source heat pump and the underground heat interchanger, regarding mixes the GSHP system, but also includes several kind of assistance heat dissipating arrangement.These simulation equipment is covered in undeshuts the circulation underground heat interchanger to shut the circulation double barrel systems to be possible to use the horizontal pipe installation or the vertical pipe installation.Vertical pipe installation system as a result of it high heat transfer efficiency by people many uses.This kind of type closed cycle heat interchanger sets at into the diameter by a root is 75mm150mm the drill hole U tube is composed.These drill holes after set at into the U tube with the earth backfill which drills or, more universal, the entire kondow pads with the thin mud.Is in the milk usually is avoids the ground water the pollution moreover causing the heat transfer pipeline with to contact completely reaches the greatly good heat transfer effect.Is commonly used the diameter is the 22mm33mmhigh density polyethylene manages (HDPE) in the system pipe installation.Punch depth generally between 30m120m.Two kind of simulation complexity are very interesting.First, the survey underground heat interchanger users smallest input design method is may take in the unit time.Next, its can forecast in for several hours (or short time curve) because the building load continuously change has what influence to the underground heat interchanger the simulation pattern also is also is may take.This theory permission and uses electricity the demand forecast to the system energy consumption.Because both method take has been presented by Eskilson(1987) development model as the foundation in this paper, the Eskison method could first discuss, then will be to by Yavuzturk and the Spitler development simulation pattern description. (1999)2.1.1 Eskison research techniquesEskison (1987) aims at the pair hole the ambient temperature distribution definite question solution uses the means which the logic analysis and the mathematical analysis unify.Regarding the initial condition and in the boundary condition constant even soil the pair hole related value establishment radial direction - axial coordinates, the use transient state finite difference equation carries on the two-dimensional value computation individually.The pipe wall and the mud and so on the individual drill hole essential factor calorific capacity is likely is neglected.The single drill hole temperature field through overlaps obtains the entire drill hole scope.The entire drill hole scope temperature response is transformed to a group of non-linear temperature feedback factor, was called makes the G- function.This G- function possibly causes the place pair opening wall temperature change situation computation which the specific heat input causes correspondingly with some time in into.As soon as passes through the drill hole scope the feedback to indicate to the steps and ladders quantity of heat feedback with the G- function that, any random temperature feedback function can because of let above a series of step function the temperature feedback/output decision, moreover superimposes to each gradient function feedback.This process expressed regarding four month-long temperature feedbacks by the graphical representation method in Figure simulation model here said the simulation model majority of details already introduced by Yavuzturk and Spitler.In this paper will be able to give its brief description.This model essential target is the application in the construction energy analysis, this model can forecast the system energy consumption take each hour as the unit.This model nationality will consummate by the Eskilson theory develops is discussed in here.The Master G- function increased the forecast frequency to an hour several times.Eskilson uses for to determine the G- function the data model not to be suitable for the short time curve survey, uses another kind of data model to survey a place pair hole short time internal heat feedback/output pulse the temperature response.Regarding the short time in hot pulse, inside and outside the radial direction position pair hole hot shift affects the axial position hot shift is much bigger than.From this, has produced one kind of two-dimensional radial direction constant volume model.The details see also Yavuzturk, et al. (1999).2.2 vertical circular hole well vertical circular hole well uses in directly carrying on the heat change with the ground.One kind used for to study the vertical circular hole well performance the data model already to research and develop, it was composed by two parts: Pair hole constitution node model, in nearby ground water flowing and ground heat transfer constant volume model.This kind of model utilization including the heat transfer which causes to the ground water flowing is clear about processing (Rees, et al.2003).This kind of model may inspect vertical circular Kong Jing the performance in the use influence and the vital significance.Its performance is most has in following several parameters sensitively: Current capacity, pair hole length, ground heat conductivity and hydraulic pressure conductivity.2.3 water source heat pump Jin and Spitler(2002a) has invented one kind of parameter estimate water source heat pump model.This kind of model carries on the thermodynamic analysis to the freezing circulation, the specific heat exchange model is simpler, simultaneously is more precise than the freezing circulation compressor model.In the second paper (Jin, et al.2002b), carries on the expansion to this model, including maneuver type air compressor sub-model and use antifreeze step.In the manufacture manufacturer table of contents data narrated in model each kind of parameter which the multivariable optimization algorithm estimates.Jin(2002) in detail narrated the parameter which the multivariable optimization algorithm and estimates.Compares the equation - being suitable type model which before then produces, the water source heat pump model is more precise.Jin(2002) also introduced one kind of similar water source heat pump model.In 2.4 mixed style GSHP system thermal compensation source heat pump system the pair hole cost is the system cost important part, but it mainly is decided by the local geology condition.This kind of equipment mainly uses in refrigerating in the building.Is bad in this kind of ground thermal conductivity, drill hole condition crude place, water source heat pump system cost quite expensive.For all this, we may adopt the primary cost with to be able the effect compromise means, reduces the pair hole scope, installs the assistance heat dissipating arrangement in the heat pump water pipe.Such system is called the mixed source heat pump system.In the mix system water pipe has each kind of different type heat dissipating arrangement, for instance the cooling tower, brings the heat interchanger shallow pool, the hydraulic pressure heating surface or is called the bridge level.Chiasson(2002a) has invented the shallow pool model, its principle is: Because shuts the circulation heat interchanger, needs to install the counter-flow heat transfer installment in the water level surface mounting natural heat transfer installment foundation.Chiasson(2000b) simultaneously also invented one kind to be suitable in the hydraulic pressure heating surface or is called the bridge level the finite difference model.This kind of model even can imitate the snow melting process.The above these model use experimental assistance heat dissipating arrangement, obtains the approval in Oklahoma State University.1. soil quantity of heat characteristic scene determination survey in-depth ground heat conductivity regarding the place source heat pump system very important.The pair hole width length mainly is decided by in-depth ground hot nature.The determination in-depth ground heat conductivity traditional method is first definite around the pair hole the ground type.After the determination, may determine its heat conductivity through Double barrel Heat pump System design Handbook about the ground type material (EPRI1989).According to the report, in the ground information heat conductivity has a more widespread value, therefore could find one kind of more precise surveying to decide the ground heat conductivity method to be better. The in-depth ground heat conductivity cannot the immediate determinant, only be able to infer through the tepid transformation measuring method, but also must use some geothermy transmission pattern, for instance linear water source law (Ingersoll and Plass1948; Mogensen1983) or cylindrical water source law (Carslaw and Jaeger1947).Interesting is they also has the opposite use - - to determine its hot nature by the ground performance, but is not determines its performance by the ground hot na