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1、精选优质文档-倾情为你奉上地热源换热什么是地热交换系统？地热交换系统是以电力为动力，对内部空间作用的制冷系统。这个系统利用地球内部（或者池塘湖泊）作为热源或者冷源。这个系统由热泵，循环泵，地热交换器和支管系统组成。大多数地热交换系统用风道作为分配子系统，在地源侧用聚乙烯管进行热量交换。什么是热泵？热泵是以电为驱动力，将热量从一个区域传递到另一个区域的机械装置。典型的空调就是一种热泵，它将内部空间的热量裹挟到室外并释放到空气中。然而，不像典型的空调机，一个真正的热泵可以向任何一个方向运转，热泵可以将热量从空间带走，也可以将外部的热量送入室内。什么是地源热泵与空调机通过冷凝器（一个像盒子似的，放在
2、室外，并且运行时会产生噪音的装备）向周围环境传递热量不同，地热交换热泵在制冷模式下将热量传递给土壤，在加热模式下从土壤中取出热量。地热交换热泵通常被称为地源热泵。地源热泵系统是如何工作的？地源热泵系统，与普通的热泵系统和空调机类似，利用制冷剂将热量带入或者带出你的房间，地源热泵系统的制冷剂的作用应用到了热量传递的两个基本规则。热量总是从温度较高的区域传向温度较低的区域。两个相邻区域的温差越大，二者之间的热量传递效率越高。冰箱，空调，和热泵都是在封闭的环路中通过压缩机制造出两个温差明显的低温区和高温区。最简单的例子就是我们熟知的家用冰箱。在电冰箱中，风扇吹机壳内装满低温制冷剂的盘管（比较典型的是
3、低于零度），热量从内部空气流向冷却器的制冷剂。之后制冷剂被蹦到暴露在室外的高温区域，由于制冷剂在这个区域比较热，所以在制冷剂流回低温区继续开始下一个循环之前将热量抛给温度较低的室内空气。地源热泵系统工作原理与之相似，除此之外还汲取屋子内或建筑物内部的热量并运输到建筑物外部空气中。传统的热泵加上一个转换的功能，冷源和热源就可以进行切换。随着冷热源的转换，系统可以实现从室外汲取热量并运输到室内的目的。当室外空气极其寒冷时，传统的（空气源）热泵不得不依靠电阻来加热，效率不得不被降低。地源热泵力压群雄的工作效率标准的热泵，操作相对简单，面向一个主要的人群。当热量需求很大时，他的效率是最低的。当我们需求
4、很高的性能时，空气源热泵不得不努力的工作。如上所述，一个合格的空气源热泵，冬天时从室外吸收热量，夏天时将热量“扔”到室外。不行的是，室外空气越冷，从外界吸收热量越困难。温度越高，越难将热量“扔”到室外。两种情况下，空气和制冷剂之间的温差都是很小的，这个系统降低了传热效率。但是，室外越冷，通过窗户，门以及外墙和地板的热量损失的效率就越高，通过热泵维持室内空气舒适所需的热量就越多。夏天，我们陷入了类似的困境。室外越热，热量渗透到室内的效率就越高，维持舒适度所需排热量就越多。地源热泵系统通过使用温度相对恒定的地源解决了这个难题，使其在冬季作为热源，夏季作为散热器，用地球代替了室外空气。贯穿美国历史，
5、冰冻线以下的地温（地表以下35英寸）基本上维持在恒定的温度，通常在北纬45-50度，南纬50-70度。因此，在冬季，地热交换系统从比室外空气温度相对高的地球吸收热量。夏天，可以向比室外空气冷得地球排除热量。由于制冷剂与地源温度的温度差在两个季节都相对较高，所以传热效率更高。所以，地源热泵系统一年的工作效率比普通的热泵系统高很多。地源热泵系统的清洁度安装地源热泵系统是对环境负责的表现。因为地源热泵系统只是在冬天从地下向你的房间传递热量，而不用你燃烧任何的化石燃料以加热室内环境。与其他供热系统相比，它大幅度的降低了二氧化碳的排放量，并且完全消除了产生二氧化碳等烟气的源，用地源热泵系统替换传统的燃气
6、炉供暖系统，是安全健康的环境友好型设备。与地球连接起来地源热泵独特的方面，其好处一长串的关键，是接地回路的存在。接地回路为夏季向地球内部传递热量，冬季从其内部吸收热量提供了途径。有闭式系统和开式系统两种循环。首先，让我们看看典型闭式系统中的制冷剂循环。物理上来看，地下循环包含数米长的塑料管，他们安装在围绕着地球的水平的暗沟或者竖直的井里，地管回路中的水由水泵泵到地热系统的换热器中，在夏天，从制冷剂的热区域吸收热量并通过地管回路运输至地下。冬天，通过地管回路从地下吸热并运输到制冷机的冷区域。地下管路的长度由冷热负荷决定，冷热负荷又由你房间的设计施工方法，方位和居住地的气候条件觉得的。水平或竖直安
7、装的地下管路是否能获得最大的有效容量，是由地表土的类型（岩层，砂土层或者黏土层等），所在区域的深层土的地质条件，以及地热的可利用性。通常水平安装管线的安装造价比较低，但是需要占用更大的面积。竖直安装管线需要更少的地表面积，而钻孔的造价更高。另一个接地的方案，一个开式系统，牵涉到使用井来代替闭合的管线。在水源丰富的地区，可以将水从井里抽出来，通入地热系统的换热器，然后再抽回到另一个井进行地下水回灌。由于水仅仅吸收或者放出热量，但是没有改变其他任何东西，这些水离开热泵的时候像进入热泵时一样纯净。当拥有适当的型号时，这两种方案的任何一个都同样是该效率的。而且，地下管线一旦安装，你几乎可以忘掉它。聚乙
8、烯管在地下或者水的作用下不会降解，不会受侵蚀，也不会被折断，所以这个装置有望沿用五十年或者更长时间。多余的热水作为一个额外的收益，大多数地源热泵系统可以设计成在夏天可以在空调制冷的季节吸收室内的热空气的热量生产多余的热水。甚至在冬天，地源热泵系统的废热可以被转换到热水中以减小热水加热器的热量消耗。结论根据环境保护署的说法，地源热泵系统是最高效能的，清洁的，空间成本效益好的可利用的调节系统。美国环保署确认地源热泵系统优越的效率,发现即使在源燃料基础-会计为所有损失包括发电燃料循环电厂的平均提高地源热泵机组的效率比空气源热泵机组高40%、比燃气加热炉效率高48%,比燃油炉效率高75%今天最先进的地
9、源热泵系统在制冷循环中胜过最先进的燃气采暖系统，燃气热泵系统43%。地源热泵系统利用地球的蓄热来加热冷却建筑物，并可以提供热水。地球是一个巨大的蓄能体，因为它吸收了太阳辐射能的47%比人类每年对能量的需求高出五百倍并为清洁可再生能源。在供暖季节，地源热泵系统取热的效率接近或超过百分之四百，并在制冷季节退还回去。除运转费用方面的收益外，地源热泵系统可以提供：不用化石燃料燃烧来加热。一氧化碳和二氧化碳零排放。增加安全指数。设计维护运转简单。夏天可以得到多余的热水在院子里看不到不雅的或者发出噪音的空调机。地源热泵系统的效能等级美国环境保护署和美国能源部都认为地源热泵技术是可利用过的最高效的环境友好型
10、的加热或者冷却系统。根据环境保护署的调查，地源热泵系统获的效率比燃气炉高48%，比燃油炉高75%，比空气源热泵高40%。这些听起来极好，但是在电价比天还高的加利福尼亚，或者让私房屋主的英格兰人考虑替换油炉，如何惠及他们呢？这个分析力求调查到地源热泵系统与其他传统的空调系统的造价开销比较，这里强调为消费者将其作为工具来确定设施预期运行费用，需要替换新设施的时间提供了一个现实的工具。地源热泵系统vs空调系统几乎所有的传统住宅和需要采光的商业建筑都使用空气调节系统来为内部空间制冷。这些系统在室外都有一个冷凝器。一半将制冷器，加热器和空气源热泵安装在一起。全部使用室外空气来给制冷剂降温，同时将热量扔到
11、周围的空气中。这个讨论的目的，所有这些设施被称为空气源设备。比较地源热泵系统和传统的空气源热泵机组是很复杂的，由于室外空气温度的原因，空气源热泵系统的效率急剧下降。空气源热泵设备生产厂商在高效率模型机上给用户制造高能效比和高季节能效比的印象，但是最近检测的实际数据表明这些高数据与现实的安装环境与条件无关联。一个典型的例子，厂商标注一个三吨的空气源热泵机组的能效比为12.0.然而，最近的一个着眼于在额定工况下能效比绩效的统计值为10.5（冷凝器的进口温度为95 F，蒸发器的失球温度为67 F）。这就表示白天的温度大约为95 F,。当室外温度升高到100 F，空气源设备的能效比下降到9.2，表示能
12、效比下降了12%。如果室外温度上升到110 F，能效比将下降到7.7，表明能效比下降27%。这意味着这个机组需要额外的27%的电能来维持原来的制冷量。另一方面，空气源热泵机组的制冷能力与室外空气温度有很大关系。当室外的空气温度为95 F时，一个标准的三吨的空调机组可以作为三吨的使用，但是当室外空气升高至110 F，这个机组只能当做2.6吨的使用，下降14%。冷凝器被污垢或者碎片堵塞，更将会降低效率。地源热泵系统的能效设计不依赖室外空气温湿度的变化。因为不管地源热泵选择在任何区域，一年中地球的温度基本上都是恒定不变的。任何季节，加热和制冷的总效率都是确定。的，标准的三吨的机组，冷凝器冷却水进口温
13、度为60 F时，能效比大约为18。和空气源机组比较与室外空气关系的不同：能效的分析比较就像是苹果与苹果的比较。着还没有包括回热器在内，其重要作用的热水容器。在夏天，如果这些效能被用于给传统的燃气或者电加热器提供热水的话，效率将变得更高。在运行中的减温器的作用下，夏天产生的热水在热泵系统中变成多余的了。地源热泵系统vs燃气炉系统比较地源热泵系统和燃气炉的造价，很多原因都很难进行评估。首先是气和电价格在不同时间和不同区域的巨大差别。从美国能源信息管理局收集的数据来看，在2000年，天然气价格从阿拉斯加州的3.57到夏威夷的21.87美元不等。忽略这两个州，仍然存在从密歇根州的5.17美元到康乃狄克
14、州的11.29美元。试图定一个相同的电费标准也是同样的困难的。美国电子工业联合会提供的数据表明，2000年，电费价格从华盛顿的0.05美元到夏威夷的0.16美元不等。另外，试图比较燃气炉和GHP，需要将季节性的价格波动考虑进去。通常，天然气价格在冬天比较高，而电价又是在夏天比较高。根据这写些析，我们可以拿典型的高效率的燃气炉和地源热泵机组进行比较。燃气炉的效率为80%，COP值为3.5.计算表明，当电价等于天然气价格的0.15倍时将会出现均衡点。例如，如果燃气每CCF为一美元，达到效益平衡点时，耗电为0.15美元每千瓦。因此如果电费消耗每千瓦便宜0.75美元，这样得到的能效更经济。这项分析综合
15、考虑了各州从1999-2000，和2000-2001年冬季的天然气和电价的平均值。我们还用到了在同一时期所有州居民平均用电量。自从2000-2001年，天然气价格喜剧性的急剧上涨，我们要总管两种情况。1999-2000天然气平均价格是0.94/CCF,然而电价是8美分每千瓦。我们可以清楚的看出他们的交点就是所谓的绿色区域。实际的计算显示，运行三吨的热泵机组，天然气机组每小时耗资31美元，GHP系统每小时23美元。这表明能源节约大约为26%。2000-2001年天然气的平均价格为0.94美元/CCF，而当时的电费价格为8美分每千瓦。我们可以清楚的看出他们的交点即为深绿色区域。实际计算显示，运行三
16、吨的加热机组，对于天然气机组每小时为42美元，而对于GHP则为23美元。这代表在能源上节约45%。地源热泵机组vs燃料油加热机组类似于与天然气的比较，这二者之间的比较是很难进行评价的。燃油价格随着季节和原油价格波动比较频繁。在这个分析中，我们将比较一个标准的燃油加热机组和地源热泵机组的效率。燃油加热机组的效率为80%，地源热泵机组的COP值为3.5。计算表明当达到均衡点的时候，每千瓦的电价为每加仑汽油的0.107倍。例如，如果每加仑汽油的价格为1美元，那么GHP系统的电价就相当于10.7美分。因此当在这种情况下是，电价在10.7美分以下，所以.GHP系统是最经济的。计算表明运行一个三吨的设备，
17、燃油系统造价为每小时41美元，而GHP系统为23美元，因此，运行GHP 系统节能41%。结论这里的分析和环境保护局的结果是一致的，我们应该做出适当的选择。很明确，与其他所有加热和空气源系统相比，地源热泵系统是最引人注目的，运行起来高效率、低消耗的空调系统。Ground Source Heat ExchangeWhat is a GeoExchange System?A geoexchange system is an electrically powered heating and cooling system for interior spaces. This system utilizes
18、 the earth (or a pond or lake) for both a heat source and a heat sink. Components of this system include a heat pump, a hydronic pump, a ground heat exchanger, and a distribution subsystem. Most geoexchange systems utilize air ducting for the distribution system, and polyethylene piping in the earth
19、 for the heat exchanger.What is a Heat Pump?A heat pump is an electrically powered mechanical device that takes heat from one location and moves it to another location. A typical air conditioner is a form of a heat pump in that it takes heat out of the interior space and then rejects that heat outdo
20、ors. However, a true heat pump can work in either direction, unlike a typical air conditioner. A heat pump can take heat out of an interior space, or it can put heat into an interior space.What is a GeoExchange Heat Pump?Unlike the air conditioner that rejects heat into the surrounding air through t
21、he condenser (which resembles a caged box, sits outside the house, and makes noise when it turns on), the geoexchange heat pump rejects heat into the earth during the cooling mode, and takes heat out of the earth while in the heating mode. GeoExchange Heat Pumps are more commonly referred to as Grou
22、nd Source Heat Pumps. (See Notes)How GeoExchange Systems WorkGeoExchange systems, like common heat pumps and air conditioners, make use of a refrigerant to help transfer (or pump) heat into and out of your home. The refrigerant helps the GeoExchange system take advantage of two primary principles of
23、 heat transfer:1. Heat energy always flows from areas of higher temperature to areas of lower temperature. 2. The greater the difference in temperature between two adjacent areas, the higher the rate of heat transfer between them. Refrigerators, air conditioners, and heat pumps all operate by pumpin
24、g refrigerant through a closed loop in a way that creates two distinct temperature zonesa cold zone and a hot zone.The simplest example of such a system is the universally familiar home refrigerator. In a refrigerator, a fan blows the air inside the box over tubes containing refrigerant that is very
25、 cold (typically below 0 F). Heat flows from the interior air to the cooler refrigerant. The refrigerant is then pumped to the high-temperature section, which is exposed to room air outside the refrigerator box. Because the refrigerant is hot in this zone, it gives up heat to the relatively cooler a
26、ir in the room, before flowing back to the cold zone to begin the loop again.An air conditioner works in exactly the same way, except that it extracts heat from the air inside a room or building and transfers it to the air outside the building.A conventional heat pump adds a reversing capability, so
27、 the hot zone and the cold zone can be switched. With the zones reversed, it can extract heat from the outside air in the winter and transfer it inside.Granted, being able to extract heat from frigid winter air seems like it shouldnt work, but it will if we can expose the cold air to refrigerant tha
28、ts even colder than it is. And modern heat pumps can do that.When the outside air gets extremely cold, the conventional (air source) heat pump has to resort to electric resistance heating. This reduces efficiency dramatically.The Super Efficiency of GeoExchangeStandard (air source) heat pumps, while
29、 relatively simple to operate, face one major challenge: their operating efficiency is lowest when demand is highest. That is, heat pumps (air source) have to work hardest when we demand the most performance from them.As weve just seen, a regular heat pump (air source) extracts heat energy from outs
30、ide air in the winter, and rejects heat to outside air in summer. Unfortunately, the colder the outside air, the more difficult it is to extract heat from it, and the hotter the outside air, the harder it is to transfer heat to it. The temperature difference between the air and the refrigerant is sm
31、all in both cases, lowering heat transfer rates within the system.Yet, the colder it gets outside, the higher the rate of heat loss through windows, around doors, and through walls and roofs, and the more heat we need to pump inside to keep indoor temperatures comfortable. In summer, we face a simil
32、ar dilemma. The hotter it gets outside, the higher the rate of heat infiltration into the house, and the more heat removal we need to maintain comfort.A GeoExchange system eliminates this dilemma by using the relatively constant temperature of the earth as a heat source in winter and a heat sink in
33、summer, instead of outside air.Throughout most of the U.S., the temperature of the ground below the frost line (about 3 to 5 feet below the surface) remains at a nearly constant temperature, generally in the 45 -50 F range in northern latitudes, and in the 50 -70 F range in the south. So, in the win
34、ter, a GeoExchange unit can extract heat from the earth thats relatively warm compared to the cold outside air, and in the summer, it can discharge heat to the earth that is relatively cool, compared to the hot outside air. Since the difference between the refrigerant temperature and the ground temp
35、erature remains relatively high in both seasons, so do heat transfer rates. Consequently, the GeoExchange system operates at much higher year-round efficiencies than a standard heat pump.The Cleanliness of GeoExchange SystemsInstalling a GeoExchange system is environmentally responsible. Since a Geo
36、Exchange system merely transfers heat from the ground into your home in winter, you dont need to burn any fossil fuels to create a warm interior environment. The approach drastically reduces carbon dioxide emissions (a greenhouse gas) compared with the operation of other heating systems, and complet
37、ely eliminates the heating system as a potential source of carbon monoxide fumes within your home making the GeoExchange system an environmentally friendly as well as safe and healthy alternative to traditional oil and gas furnaces.Making The Ground (Earth) ConnectionThe unique aspect of the GeoExch
38、ange system, and the key to its lengthy list of benefits, is the “ground loop.” The ground loop provides the means of transferring heat to the earth in summer, and extracting heat from the earth in winter. There are “closed loop” and “open loop” systems. First, lets look at typical closed loop syste
39、ms that recycle the same water (the refridgerant) endlessly.Physically, the ground loop consists of several lengths of plastic pipe typically installed either in horizontal trenches or vertical holes that are subsequently covered with earth and landscaping of your choice. Water inside the ground loo
40、p piping is pumped through a heat exchanger in the GeoExchange unit. In the summer, it absorbs heat from the refrigerant hot zone and carries it to the ground through the ground loop piping. In winter, it absorbs heat from the earth through the ground loop, and then transfers that heat to the refrig
41、erant cold zone.The length of the ground loop will be determined by the heating and cooling loads, which are determined in turn by the size of your home, its design and construction, its orientation, and the climate where you live. Whether the ground loop is most efficiently installed in horizontal
42、trenches or in vertical boreholes depends on the type of soil near the surface (rocky, sandy, clay-laden, etc.), the geology of the deeper terrain in your area, and the amount of land available. Generally, horizontal loops are less expensive to install, but require more land area. Vertical holes req
43、uire much less land area, but require the expense of drilling.Another ground connection scheme an “open loop” system involves using wells instead of closed loop piping. Where water is plentiful, it can be pumped out of a well, through the heat exchanger at the GeoExchange unit, and then pumped back
44、into another well to return to the groundwater. Since the water merely absorbs or gives up heat, but is not altered in any other way, it leaves the GeoExchange unit as pure as it was when it entered it.Any one of these installation schemes results in the same high efficiency, when properly sized.Mor
45、eover, once the ground loop is installed, you can typically forget about it. The polyethylene piping (the same type used for cross-country natural gas lines) does not degrade, corrode, or break down in ground or water contact, so sound installations are expected to last 50 years or more.Free Hot Wat
46、erAs a side benefit, most GeoExchange systems can be designed to produce free hot water during the summer, by using waste heat extracted from the interior air during the air conditioning season. Even in the winter, waste heat from the GeoExchange heat pump can be converted to hot water to reduce the
47、 energy costs of the hot water heater.ConclusionGeoExchange is the most energy-efficient, environmentally clean, and cost-effective space conditioning system available, according to the Environmental Protection Agency. The EPA confirmed the superior efficiency of GeoExchange, finding that even on a
48、source fuel basis accounting for all losses in the fuel cycle including electricity generation at power plants GeoExchange systems average 40% greater efficiency than air source heat pumps, 48% greater efficiency than gas furnaces, and 75% higher efficiency than oil furnaces. Todays best GeoExchange
49、 systems outperform the best gas technology, gas heat pumps, by an average of 36% in the heating cycle and 43% in the cooling cycle.GeoExchange systems use the Earths energy storage capability to heat and cool buildings, and to provide hot water. The earth is a huge energy storage device that absorbs 47% of the suns energy more than 500 times more