本文關鍵詞： 地埋管換熱器 換熱性能 熱滲耦合 土壤分層 熱響應試驗 數(shù)值模擬　出處：《長安大學》2014年碩士論文　論文類型：學位論文

【摘要】：土壤源熱泵技術作為一種可再生能源利用技術，利用土壤這一天然的蓄熱體可實現(xiàn)能源的跨季度利用。其以節(jié)能環(huán)保、機組能效系數(shù)高、運行管理穩(wěn)定方便等優(yōu)點廣泛應用于工程實踐中。采用豎直U型地埋管換熱器的土壤源熱泵系統(tǒng)更適合我國人均占地面積小的國情。土壤源熱泵系統(tǒng)的綜合性能主要取決于地埋管換熱器的換熱性能，研究地埋管換熱性能的影響因素以強化埋管與土壤之間的換熱可以有效提高熱泵系統(tǒng)的綜合性能。在進行巖土熱響應試驗時，這些影響因素直接表現(xiàn)在對試驗結(jié)果造成一定偏差，而巖土熱物性參數(shù)是土壤源熱泵系統(tǒng)地埋管換熱器設計的基礎依據(jù)，應準確測量。 鑒于此，本文對豎直U型地埋管換熱性能的影響因素進行了探討研究。首先建立了耦合地下水滲流和巖土熱物性分層的豎直U型地埋管換熱器全尺寸三維模型，利用專業(yè)數(shù)值模擬軟件Fluent對巖土熱響應試驗過程進行數(shù)值模擬。對數(shù)值模擬過程中地埋管內(nèi)流體進出口溫度的變化及周圍土壤溫度的變化進行了監(jiān)測和分析，并對比分析現(xiàn)場熱響應試驗和熱響應數(shù)值模擬的結(jié)果，驗證了該模型的合理性和可靠性。 本文應用此數(shù)值模型對地下水位變化、同一水位下不同地下水滲流速度及巖土導熱系數(shù)分層等不同條件下的熱響應試驗進行數(shù)值模擬，分析其對地埋管換熱性能的影響；并通過解析計算模型，對模擬所得數(shù)據(jù)進行分析，得到巖土綜合熱物性參數(shù)，研究這些因素對熱響應試驗的影響。此外，本文還針對土壤源熱泵系統(tǒng)初期運行對系統(tǒng)性能存在不利影響的現(xiàn)象，進行量化分析，研究起始運行時間不同對土壤源熱泵性能的影響。結(jié)果表明，地下水位埋深越大，地埋管換熱性能越差；地下水滲流作用可增強埋管的換熱性能，且速度越大，作用越顯著；在平均導熱系數(shù)相同時，分層條件下埋管換熱性能比均勻土質(zhì)條件下要差；地下水位、地下水滲流速度及巖土導熱系數(shù)分層的變化都會對熱響應試驗結(jié)果產(chǎn)生一定影響；在供冷季，熱泵系統(tǒng)從5月1日開始運行時的機組COP不如熱泵系統(tǒng)從11月15日開始運行時，，比其低1.8%；在供暖季，熱泵系統(tǒng)從5月1日開始運行時的機組COP比熱泵系統(tǒng)從11月15日開始運行時要好，比其高1.3%。
[Abstract]:As a kind of renewable energy utilization technology, the ground-source heat pump technology can realize the inter-seasonal utilization of energy by using the soil as a natural regenerator, which is energy saving and environmental protection, and the unit energy efficiency coefficient is high. The advantages of stability and convenience of operation and management are widely used in engineering practice. The ground-source heat pump system with vertical U-type ground heat exchanger is more suitable for the situation of small per capita occupation of land in China. The comprehensive performance of ground-source heat pump system. It mainly depends on the heat transfer performance of buried tube heat exchanger. In order to enhance the heat transfer between buried pipe and soil, the comprehensive performance of heat pump system can be improved effectively by studying the influencing factors of heat transfer performance of buried pipe. These influencing factors are directly reflected in the deviation of the test results, and the geotechnical thermal properties are the basis for the design of ground-buried heat exchangers in the ground-source heat pump system, which should be measured accurately. In view of this. In this paper, the factors affecting the heat transfer performance of vertical U-type buried pipes are studied. Firstly, a full-scale three-dimensional model of vertical U-type buried pipe heat exchangers is established, which is coupled with groundwater seepage and thermal stratification of rock and soil. The thermal response test process of rock and soil was simulated by the professional numerical simulation software Fluent. The variation of the inlet and outlet temperature of the fluid in the buried pipe and the change of the soil temperature around the buried pipe during the numerical simulation were monitored. And analysis. The results of field thermal response test and thermal response numerical simulation are compared to verify the rationality and reliability of the model. In this paper, the numerical model is used to simulate the thermal response tests under different conditions, such as the variation of groundwater level, the different seepage velocity of groundwater and the stratification of thermal conductivity of rock and soil under the same water level. The influence on the heat transfer performance of buried pipe is analyzed. Through the analytical calculation model, the simulated data are analyzed, the comprehensive thermal physical parameters of rock and soil are obtained, and the influence of these factors on the thermal response test is studied. Aiming at the phenomenon that the initial operation of ground-source heat pump system has adverse effect on the performance of the system, quantitative analysis is carried out to study the effect of different initial operating time on the performance of ground-source heat pump. The deeper the groundwater level is, the worse the heat transfer performance of the buried pipe is. Groundwater seepage can enhance the heat transfer performance of the buried pipe, and the greater the velocity, the more obvious the effect. When the average thermal conductivity is the same, the heat transfer performance of buried pipe under stratified condition is worse than that under homogeneous soil condition. The variation of groundwater level, groundwater seepage velocity and thermal conductivity of rock and soil will have a certain effect on the results of thermal response test. In the cooling season, the COP of the heat pump system is lower than that of the heat pump system from November 15th when the heat pump system starts to run on May 1st. In the heating season, the COP of the heat pump system when it started operation from May 1st is better than that of the heat pump system from November 15th, and is 1.3 times higher than that of the heat pump system.
【學位授予單位】：長安大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TU83

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