外文翻譯---氣候條件對地源熱泵系統(tǒng)性能的影響

1、<p>　　外 文 翻 譯</p><p>　　題 目： 氣候條件對地源熱泵系統(tǒng)性能的影響 </p><p>　　氣候條件對地源熱泵系統(tǒng)性能的影響</p><p>　　摘要：在中國的建筑物中，初級能源的30％用于加熱和冷卻。在這方面應用最廣泛的設備是鍋爐和空調。在許多應用中，熱泵是唯一能滿足加熱和冷卻要求的運行方式，因為他們可以利

2、用建筑物周圍的可再生能源。在本文中，對氣候對應用地源熱泵系統(tǒng)技術的影響進行了對比討論。對結果進行分析能得出以下結論：如果只從土壤中吸取熱量，在兩個月后，地源熱泵附近的土壤溫度將減少到20攝氏度以下 。如果向土壤排入相同的熱量三個月，土壤溫度將會超過37攝氏度，那將不再適合于空調系統(tǒng)。為了使作為熱源/冷源的土地資源實現(xiàn)可持續(xù)利用，就應該使向土地排入的熱量與從土地吸取的熱量保持平衡。在一些熱不平衡的工程實例設計中，一些措施是可以考慮的。&l

3、t;/p><p>　　關鍵詞：氣候條件；地源熱泵；熱不平衡</p><p><b>　　1.導言</b></p><p>　　用于家庭取暖和降溫的能源消費量在世界能源消費量中所占的比例是一樣的。在中國大約一半的初級能源是以煤的形式供給的，而煤是不可再生能源。在很多應用中，地源熱泵(GSHPs)是供暖和降溫的最有效方式，因為它們依賴于建筑物周圍的可再

4、生熱源。Lund JW(2000)指出地源熱泵系統(tǒng)可以看成一個能高效利用能量的機械系統(tǒng)，而且比空氣源熱泵多了幾個明顯的優(yōu)點。主要有：(a)他們消耗較少的能量來維持運轉，(b)在極低的外界溫度下，他們不需要補充熱量，(c)他們使用較少的制冷劑，(d)他們的設計比較簡單，并且后期的維修保養(yǎng)費用較少，(e)他們并不需要專門的設備去查找那些因暴露而風化的部位。不過，主要的缺點是初期投資比較高，大約比空氣源設備高出30－50％。這是由于要花費額外

5、的人力物力來埋設熱交換器或者為能源提供一口儲蓄井。但是，一旦安裝完畢后，就整個系統(tǒng)的使用壽命而言每年的費用是比較低的，從而導致了凈儲蓄[1,2]。在地源熱泵應用中，對土壤熱能的儲存或提取是通過地熱換熱器(GHE)實現(xiàn)的。地熱換熱器和貼鄰的土壤之間的傳熱主要是熱傳導并在以一定程度上是以水分遷移的方式實現(xiàn)的[3]。因此，它主要依賴于土壤類</p><p><b>　　2.系統(tǒng)說明</b><

6、/p><p>　　構成試驗系統(tǒng)的示意圖如圖1所示。該系統(tǒng)主要由兩個獨立的環(huán)路構成：(a)水環(huán)路，(b)冷媒環(huán)路。在水環(huán)路中配置一個水塔，以補給足夠的水。冷媒環(huán)路是由兩個閉環(huán)銅管組成的。熱泵的工作流體是R-22。圖3中給出了這三個地熱換熱器的主要特點，圖3中標有(a)單U型管，(b)雙U型管，和(c)套管。這些地熱換熱器在并聯(lián)接法方式下運行。圖2中描繪了地熱換熱器的配置線路。</p><p>　

7、　圖1.地源熱泵系統(tǒng) 圖2.地熱換熱器周圍熱電偶的分布</p><p>　　地熱換熱器有30米的深度，換熱器間的間距是5米。沿地熱換熱器垂直布置六個熱電偶，用來獲取土壤的溫度。從上往下，這六個熱電偶之間的距離是10米、8米、6米、3米和3米(圖2)。圖2中的黑色圓點表示了熱電偶的位置。熱電偶的輸出溫度被傳輸?shù)綌?shù)據(jù)記錄器中并記錄在計算機中。熱電偶也被用來測量水和冷媒的進出口溫

8、度。為了獲得地熱換熱器的進出口水溫或者冷凝器和蒸發(fā)器的冷媒溫度，熱電偶被安置在管內的各個測試位置。正如圖1描繪的那樣，轉子流量計被用來獲取每一個地熱換熱器的流速。制熱循環(huán)轉換到制冷循環(huán)是通過一個四通閥實現(xiàn)的。從夏季到冬季該實驗室都能夠適應。</p><p>　　圖3.垂直式地熱換熱器的鉆孔示意圖</p><p>　　(a) 雙U型管(b) 單U型管(c) 套管</p><

9、;p><b>　　3.結果與討論</b></p><p>　　對地源熱泵進行的各項測試是在穩(wěn)態(tài)條件下進行的，以確定整體系統(tǒng)的性能特點。對于每個鉆孔，鉆孔壁所反映的溫度(土壤溫度)是由構成地熱換熱器的兩個部分加熱達到的：一部分溫度增加/減少是由于運行過程中鉆孔本身的線源(U型管)所導致的，另一部分是由土壤的濕度所導致的。</p><p>　　(a)夏季

10、 (b)冬季</p><p>　　圖4.不同季節(jié)周圍空氣的溫度和濕度的分布</p><p>　　土壤濕度主要受空氣濕度的影響。圖4中分別顯示了夏季和冬季周圍空氣的平均溫度和濕度的分布情況。該圖顯示夏季平均溫度是29攝氏度，冬季平均溫度是16攝氏度。空氣濕度隨季節(jié)變化而有很大波動并且在夏季最高?？諝獾钠骄鶟穸仍谙募臼?0％，在冬季是50％。因

11、為在廣州夏季持續(xù)的時間要比冬季長，所以該項測試在夏季持續(xù)了100天，而在冬季只持續(xù)了49天。</p><p><b>　　(a)夏季</b></p><p><b>　　(b)冬季</b></p><p>　　圖5.不同季節(jié)換熱器周圍的土壤溫度</p><p>　　圖5.(a)和(b)顯示了不同季節(jié)

12、20米深度處的土壤日平均溫度。熱泵開啟40小時后作為記錄起始點。在試驗的開始階段，夏季的土壤溫度是28攝氏度。由試驗得知，土壤溫度迅速上升。逐漸地，從第40天至第90天，由于正處于熱平衡狀態(tài)，溫度的升高很輕微，最后不同鉆孔的溫度停留在一個穩(wěn)定的點，此時平均溫度超過37攝氏度。冬季的土壤溫度呈現(xiàn)相反趨勢，從開始的22攝氏度左右降到穩(wěn)態(tài)下的17攝氏度以下。在這里必須指出，當夏季土壤溫度高于37攝氏度和冬季低于17攝氏度之后，熱泵開始間歇運行

13、。這就是說，土壤溫度已達到其傳熱的極限容量，已不再滿足空調系統(tǒng)運行的條件。</p><p>　　(a)夏季 (b)冬季</p><p>　　圖6.不同季節(jié)不同地熱換熱器的傳熱能力</p><p>　　(a)土壤溫度分布 (b)傳熱能力分布</p&g

14、t;<p>　　圖7.制冷模式下運行一年后的土壤溫度和不同地熱換熱器的傳熱能力</p><p>　　在不同季節(jié)受空氣溫度、濕度和土壤溫度的影響，不同地熱換熱器的傳熱能力有很大的變化。正如圖6.(a)和(b)分夏季和冬季所顯示的那樣，隨著運行時間的延長，不同地熱換熱器的每米傳熱能力逐漸下降。在夏季，單U型管和雙U型管每米傳熱能力的變化幅度大致是一樣的，從開始約40瓦特/米下降到30瓦特/米以下，特別地

15、，在運行40天后，其降幅最大。在運行40天后，套管的傳熱能力下降到20瓦特/米以下。原因就是上文所述的土壤傳熱特性日益惡化。這于圖6.(b)所呈現(xiàn)的相類似。熱泵停止運行一段時間后，單U型管和雙U型管的傳熱能力將從起始的60瓦特/米下降到能從土壤吸取熱量的45瓦特/米以下。套管的傳熱能力將從45瓦特/米下降到25瓦特/米以下。正如上文所述，熱泵系統(tǒng)不能連續(xù)運行。運行一年后，土壤溫度要恢復到熱泵能夠再次運行的水平。圖7.(a)顯示了制冷模式

16、下運行一年后的土壤溫度。土壤溫度從開始的25攝氏度上升。圖7.(b)顯示了制冷模式下運行一年后地熱換熱器的傳熱能力分布情況。能夠看出，在相同的運行階段，這三種地熱換熱器的傳熱能力與圖6.(a)所示的相比是比較高的。對結果進行分析可以得出，在混合運行一定時間后</p><p><b>　　4.結論</b></p><p>　　本文進行了一系列試驗，來說明氣候對應用地源熱

17、泵系統(tǒng)技術的影響。從結果可以看出，氣候條件對地源熱泵系統(tǒng)性能的影響非常顯著。如果僅是吸取熱量，兩個月后，換熱器附近的土壤溫度將會下降到20攝氏度以下。如果僅是排入熱量，三個月后，土壤溫度將會超過37攝氏度，這已不再滿足空調系統(tǒng)的運行條件。為了使作為熱源/冷源的土地資源實現(xiàn)可持續(xù)利用，就應該使向土地排入的熱量與從土地吸取的熱量保持平衡。作為最后的結論，應該使地源熱泵的地熱換熱器能夠適應具有更多優(yōu)勢的中國南方氣候。在一些熱不平衡的工程實例設

18、計中，一些措施是應該考慮的。</p><p>　　由廣州科學工程項目主辦2005Z3-D0491。</p><p>　　原文出處：Xiangyun LIU,Min YANG,Ying CHEN,etc. EFFECT OF CLIMATIC CONDITIONS ON THE PERFORMANCE OF GROUND SOURCE HEAT PUMP SYSTEM[A]. Interna

19、tional Congress of Refrigeration [C]. Beijing:2007.1-7.</p><p>　　EFFECT OF CLIMATIC CONDITIONS ON THE PERFORMANCE OF GROUND SOURCE HEAT PUMP SYSTEM</p><p>　　ABSTRACT: Heating and cooling in buil

20、dings consume about 30% of the primary energy used in China. The most widely applied systems in this aspect are boilers and air-conditionings. Heat pumps are the only monovalent action way to satisfy the requirements of

21、heating and cooling in many applications,because they can use renewable energy in the building’s surroundings. In this paper, a comparative discussion is given to the effect of climatic on applying ground source heat pum

22、p system technology.Ana</p><p>　　Key words: climatic condition, Ground Source Heat Pump, heat unbalance.</p><p>　　1. INTRODUCTION</p><p>　　Domestic heating and cooling consumption a

23、re responsible for a average percentage of world energy consumption. About half of this primary energy in China is consumed in the form of coal,which can not be regenerated. Ground source heat pumps (GSHPs) offer the mos

24、t efficient way to provide heating and cooling among many applications, as they rely on renewable heat sources of the building's surroundings. Lund JW (2000) observed that ground source heat pump system was considere

25、d to be a machine syst</p><p>　　2. System description</p><p>　　A schematic diagram of the constructed experimental system is illustrated in Figure1. This system mainly consists of two separate c

26、ircuits: (a) the water circuit, (b) the refrigerant circuit. A water tower is configured in the water circuit to supply enough water. The refrigerant circuit is built by the closed loop copper tubing. The working fluid o

27、f the heat pump is R-22. The main characteristics of three ground heat exchangers (GHE) are given in Figure 3, which are marked with (a)Single U-tube</p><p>　　Fig.1 Ground source heat pump system Fig.2 D

28、istribution of thermocouples around GHE</p><p>　　The ground heat exchangers are 30m depth, and the space between GHEs is 5m. Six thermocouples are configured along the ground heat exchange vertically to obta

29、in the temperature of soil. The distance between thermocouples are 10m、8m、6m、3m and 3m from down to up(Fig.2). The black dots in Figure 2 denote the position of the thermocouples. The output temperature of the thermocoup

30、les are transferred to a data logger and are recorded in a computer. Thermocouples are also used to measure the inlet and </p><p>　　(a) (b) (c)</p><p&g

31、t;　　Fig. 3. Schematic diagram of boreholes in the vertical GHE:</p><p>　　(a) double U-tube and (b) single U-tube.(c) cannula</p><p>　　3. Results and discussion</p><p>　　The tests co

32、nducted on the GSHP system are under steady state conditions to determine the overall performance of the system. For each borehole, its temperature (soil temperature) response on the borehole wall to heating of the GHE c

33、onsists of two parts: the primary temperature increase/decrease due to the line source (U-tube) in the borehole itself during the operation and the second one caused by the humidity of the soil.</p><p>　　(a)

34、 In summer (b) In winter</p><p>　　Fig. 4. Distributions of temperature and humidity of ambient air in different season</p><p>　　The humidity of the soil is affected mai

35、nly by the humidity of air. The mean temperature and humidity of ambient air were distributed in Fig.4 for summer and winter individually. The figures present that the mean temperature is 29℃ in summer and 16℃ in winter.

36、 The humidity of the air varies greatly all the season and is higher in summer. The mean humidity of the air is 70% in summer and 50% in winter. Because the summer season is longer than winter season in Guangzhou, the te

37、sts have been carrie</p><p>　　(a) In summer</p><p>　　(b) In winter</p><p>　　Fig.5 The ground temperature around ground heat exchanger in different seasons</p><p>　　The

38、average day ground temperature in different seasons at 20m depth are presented in Fig.5(a) and (b).The initial points are taken 40 hours after the pump start. At the beginning of the experiment,the ground temperature is

39、about 28℃ in summer. As the experiment proceeds, the temperature increases rapidly. Gradually, from the 40th day to the 90th day, because the heat balance is being established, the temperature increases very slightly and

40、 finally stays at a stable point for different boreholes</p><p>　　(a) In summer (b) In winter</p><p>　　Fig.6 Heat transfer capacity of different ground heat exchanger in

41、different seasons</p><p>　　(a) Ground temperature distributions (b) Heat transfer capacity distributions</p><p>　　Fig.7 Ground temperature and Heat transfer capacity of different ground hea

42、t exchanger at cooling</p><p>　　mode after a year running</p><p>　　Affected by the air temperature, humidity and ground temperature in different seasons, the heat transfer capacity of different

43、ground heat exchangers varies greatly. As shown in Fig6 (a) and (b) for summer and winter individually, the per meter heat transfer capacity for different GHEs decreases with the increase of the operating time. In summer

44、, the per meter heat transfer capacity of single U-tube and Double U-tube change similarly, which decrease from about 40W/m at the beginning to lower tha</p><p>　　4. Conclusions</p><p>　　This pa

45、per conducted serial experiments of the effect of climatic on applying Ground source heat pump system technology. From the results, it can be conducted that climate conditions significantly affect the performance of Grou

46、nd source heat pump system. If only extracting heat, after two months, the Ground temperature near the GHEs would be reduced to lower than 20℃. If only injecting heat for three months, the ground temperature would be ove

47、r 37℃, which was not suitable for air-conditioning an</p><p>　　*Sponsored by GuangZhou Scientific Project 2005Z3-D0491..</p><p>　　REFERENCES</p><p>　　[1] Lund JW, Ground-source (geo

48、thermal) heat pumps. Course on heating with geothermal energy: conventional and new schemes. World Geothermal Congress 2000 Short Courses[M],. Kazuno,Tohuko District, Japan: 2000. p. 209–36.</p><p>　　[2] Lun

49、d JW, Freeston DH. World-wide direct uses of geothermal energy 2000[J]. Geothermics 2001,30,29–68.</p><p>　　[3] Arif Hepbasli a,*, Ozay Akdemir a, Ebru Hancioglu,, et al, Experimental study of a closed loop

50、vertical ground source heat pump system[J], Energy Conversion and Management 44 (2003) 527–548.</p><p>　　[4] Onder Ozgener a, Arif Hepbasli, Effect of soil type and moisture content on ground heat pump perfo

51、rmance[J], Int J. Refrig. 21(1998), No. 8, 595–606.</p><p>　　[5]Olympia Zogou, Anastassions Stamatelos, Effect of climatic conditions on the design optimization of heat pump systems for space heating and coo

52、ling[J], Enengy convers,39(1998),No.7,609-622.</p><p>　　[6] W. H. Leong, V. R. Tarnawski and A. Aittomaki, Effect of soil type and moisture content on ground heat pump performance[J], Int J. Refrig. 21(1998)