本文關(guān)鍵詞：重慶某土壤源熱泵項目雙U豎直地埋管最佳埋管深度研究　出處：《重慶大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 土壤源熱泵 換熱模型 換熱量 最佳埋管深度

【摘要】：豎直埋管式土壤源熱泵其地埋管埋設(shè)深度直接影響到地埋管換熱系統(tǒng)的換熱性能和工程造價，也對整個冷熱源系統(tǒng)的可靠性和經(jīng)濟性有重要影響。本文基于某實際土壤源熱泵項目，建立出可分層設(shè)置土壤初始溫度及物性參數(shù)的地埋管群換熱模型，并采用在雙U型垂直地埋管上預(yù)埋熱電偶溫度傳感器的方式，對該項目地下埋管換熱情況進行長期監(jiān)測，通過模擬及實測相結(jié)合的方式研究出該項目的最佳地下?lián)Q熱器埋管深度范圍。 本文首先分析了U型地埋管與周圍土壤的換熱過程，并建立出三維豎直雙U型地埋管群與周圍土壤的換熱模型，該模型可以分層設(shè)置土壤的初始溫度及物性參數(shù)，更加符合項目實際情況，并對模型求解所需參數(shù)進行了詳細闡述。 其次，依托該實際項目搭建實驗平臺，以實測的方式獲取土壤初始溫度分布，監(jiān)測并采集系統(tǒng)運行時地埋管換熱器進、出水溫，流量及地下土壤溫度逐時變化數(shù)據(jù)，為模擬提供必要參數(shù)。 隨后，以實測獲取的地下土壤初始溫度分布、地埋管進水溫度和流量參數(shù)做為模擬邊界和初始條件，利用fluent軟件對系統(tǒng)在排熱及取熱工況下，，地埋管周圍土壤溫度隨運行時間的變化情況進行模擬，并與實測數(shù)據(jù)進行對比，驗證模型的可靠性。 利用驗證后的換熱模型，對排熱及取熱工況下，地埋管內(nèi)水溫變化情況及不同深度管段的單位面積換熱量進行分析，發(fā)現(xiàn)該工程地下土壤在豎直方向上物性參數(shù)的變化造成豎直地埋管換熱器在供水管前70m單位面積換熱量最大，70m以下管段單位面積換熱量出現(xiàn)較大降幅。 由此選取6種埋管深度方案：60m，70m，80m，90m，100m及110m，分別建立出相應(yīng)的地埋管管群模型，并模擬分析不同埋深方案地埋管管內(nèi)最佳流速以及不同進水溫度條件下地埋管的換熱效果。 最后，對最佳埋管深度的確定方法進行了介紹。計算出各埋深方案所需的鉆井?dāng)?shù)量及對應(yīng)的地源側(cè)水泵參數(shù)，進而計算出各自的初投資費用，對埋深方案在定流量、變溫差及定溫差、變流量運行方式下的年運行費用分別進行了計算，通過對比得出系統(tǒng)較合理的運行方式，并最終通過計算并對比各埋深方案對應(yīng)的動態(tài)費用年值得出該土壤源熱泵系統(tǒng)最佳埋管深度為80m。
[Abstract]:The depth of buried pipe directly affects the heat transfer performance and engineering cost of the buried pipe heat transfer system in vertical buried pipe type ground source heat pump (GSHP). It also has an important impact on the reliability and economy of the whole cold and heat source system. Based on a practical project of ground-source heat pump, the heat transfer model of buried pipe group can be set up in layers to set the initial soil temperature and physical property parameters. The heat transfer of underground buried pipes in this project is monitored for a long time by using the temperature sensor of embedded thermocouple on the double U vertical buried pipe. The optimum depth range of buried tube of underground heat exchanger is obtained by combining simulation and measurement. In this paper, the heat transfer process between U-type buried pipe and surrounding soil is analyzed, and a three-dimensional vertical double-U-type buried pipe group and surrounding soil heat transfer model is established. The model can set the initial temperature and physical parameters of the soil layer, which is more in line with the actual situation of the project, and the parameters needed to solve the model are described in detail. Secondly, based on the actual project to build an experimental platform to obtain the initial temperature distribution of the soil in a measured way, monitoring and collecting the temperature of the ground buried tube heat exchanger in and out of the water while the system is running. The data of flow rate and soil temperature change time by time provide necessary parameters for simulation. Then, the initial temperature distribution of underground soil, the inlet water temperature and flow parameters of underground pipe are taken as the simulation boundary and initial conditions, and the system is simulated under the condition of heat removal and heat recovery by using fluent software. The variation of soil temperature around the buried pipe with running time was simulated and compared with the measured data to verify the reliability of the model. Using the verified heat transfer model, the variation of water temperature in buried pipe and the heat transfer per unit area of different depth pipe sections are analyzed under the condition of heat discharge and heat removal. It is found that the variation of physical properties of underground soil in vertical direction results in the largest heat transfer in 70m unit area of vertical buried pipe heat exchanger. The heat exchange per unit area of the pipe section below 70 m decreased greatly. From this, six kinds of buried pipe depth schemes: 60m ~ 70m ~ 80m ~ 90m ~ 100m and 110m are selected respectively, and the corresponding models of buried pipe group are established respectively. The heat transfer efficiency of the buried pipe was simulated under the conditions of different inlet temperature and the optimum velocity of flow in the buried pipe with different buried depth. Finally, the method of determining the optimum depth of buried pipe is introduced. The drilling quantity and the corresponding parameters of the source side pump for each buried depth scheme are calculated, and the respective initial investment costs are calculated. The annual operating cost of the buried depth scheme under constant discharge, temperature difference, constant temperature difference and variable flow operation mode is calculated respectively, and the more reasonable operation mode of the system is obtained by comparison. Finally, the optimal buried depth of the GSHP system is 80 m by calculating and comparing the dynamic cost year corresponding to each buried depth scheme.
【學(xué)位授予單位】：重慶大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TU831

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