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冷热负荷失衡条件下采能区地温场的模拟研究 总被引:1,自引:0,他引:1
以北京某地下水源热泵空调系统为例,利用地下水、热耦合数值模型技术,对冷、热负荷严重不平衡条件下地下水抽灌场地温度场的年内和年际变化进行了定量模拟预测研究,并对系统长期运行的可行性进行了论证.研究结果表明:抽水井和回灌井之间的距离相对较大,抽灌井之间的"热突破"程度较低;由于空凋系统的供暖负荷显著大于制冷负荷,抽灌区温度场将呈逐年下降趋势;抽灌场地是一个开放的系统,不断与外界发生能量交换.随着热泵空调系统的长期运行,抽灌区的温度下降速率越来越小,地温场渐趋稳定;由于热泵系统的年内冷、热负荷存在严重失衡,进而对热泵系统的运行效率将产生一定影响. 相似文献
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为了合理地开发利用浅层地温能并保护地下水环境,针对地下水源热泵工程应用中出现的热贯通现象和地下水开采引起的地层变形问题,同时将地下水渗流场、温度场和地层变形量均作为评价内容,建立地下热交换系统模拟数值模型,计算并预测地下水渗流场与温度场的运移趋势及对地下水环境的影响。结合工程场地地下水源热泵系统实例,通过模拟计算,制定采用一抽两灌、100%回灌,并将春秋季及冬季加热卫生用水温度提高1.972倍或多加热1.972倍卫生用水的运行方案,预测结果表明该方案能够有效地避免热贯通问题并控制地层变形量,使地下水源热泵系统能够长期高效运行。研究思路与方法对浅层地温能的合理开发和地下水环境的保护有积极意义。 相似文献
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针对地下水源热泵抽水井与回灌井布局模式对地下温度场的影响,通过建立地下水流与温度的耦合模型,从抽灌井布置间距及抽灌井数量角度模拟分析了不同布井模式下地下水温度的变化趋势和热贯通发生的基本特性。结果表明,同类井间距对热贯通影响不显著,抽灌井间距对抽水温度及热贯通时间影响较大;从热贯通发生时间来看,抽灌井数量越多热贯通发生的时间越延迟,但从温度偏离度角度分析,系统长期运行后抽灌井数量对抽水温度偏离度影响不显著。 相似文献
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为探究常温注水井对水源热泵热贯通现象的影响,利用FlowHeat1.0软件模拟了3组情景下含水层渗流场、温度场时空分布特征,并分析了常温注水井对含水层热贯通的影响机理和抽水井水温变化规律。结果表明,常温注水井通过减小回灌井、常温注水井之间的水力坡度和延长地下水渗透途径的方式达到缓解热贯通的效果;回灌井、常温注水井流量比相同时,常温注水井在抽灌井连线的位置对含水层热贯通的影响小;抽灌量不变时,常温注水井与回灌井的流量比越大,常温注水井缓解热贯通的效果越明显;在有利地下水回灌的水源热泵系统中,布设常温注水井能有效地降低含水层热贯通程度。 相似文献
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以北京地区实际井参数刻画的单井地下水源热泵为研究对象,利用T2Well模拟器对单井系统地源热泵运行过程进行全面模拟,并对主要参数进行敏感性分析,探究对单井系统生产井温度、热突破时间的影响。距离井筒相同位置不同深度的点,埋深越大受回灌水温度的影响越小。每个运行周期结束时,温度场分布都能得到一定程度的恢复(同一周期内初始温度场相比)。水平方向渗透率同垂向渗透率的比值越大,越有利于回灌水在含水层中的运移,可有效保证热泵系统的取热温差。初步预计一个单井水源热泵系统能满足北京地区约1.5万m2面积建筑的供暖需求,约1.6万m2面积建筑制冷需求。 相似文献
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We develop and validate against experimental measurements a steady‐state two‐stage flooded refrigerant evaporator model for a heat pump drying system. A prototype two‐stage heat pump dryer test facility was designed, built and instrumented to provide the required measurements for the validation of the model. Repeatability and data quality tests were conducted to evaluate the accuracy of measurements. Experimental data could be reproduced to within ±6.5 per cent of replicated air and refrigerant side measurements for the same evaporator's air inlet conditions while the discrepancy of energy balance at the air‐side and refrigerant‐side was observed to be within ±8.9 per cent. The two‐stage evaporator model predicted the air‐side total heat and latent heat transfer of the two‐stage evaporator to within (?6.3 per cent, 7.6 per cent) and (?11.5 per cent, 9.5 per cent), respectively. On the refrigerant‐side, the model enabled the calculation of the degree of superheat to within (?10.6 per cent, 1.7 per cent). The model has shown that there is significant improvement in the heat recovered from a two‐stage evaporator system compared to a single evaporator system. In addition, the model demonstrated that the improvement in total heat recovery could be as high as 40 per cent over its base‐value when the latent to total load at the two‐stage evaporator is increased. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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间歇式热处理炉传热计算与分析 总被引:1,自引:0,他引:1
建立了台车式热处理炉炉膛传热数学模型和辐射换热器工作模型,分析了换热器的传热特性(空气预热温度、壁温、传热系数)随炉况的变化。结果表明,辐射换热器的传热特性随炉子的升温及保温过程变化而波动很大,因而对炉子的热工性能产生了影响。 相似文献
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We present the first comprehensive estimate of the final energy demand for heat in all EU28 member states for the reference year 2012, differentiated by temperature levels, comparing two different approaches. Two different calculation approaches based on different data sets yielded estimates of the total final energy demand for heat in the EU28 of 8150 PJ and 8518 PJ in 2012, respectively. Approach 1 distinguishes between three different process heat (PH) temperature levels and results in final energy demand for heat <100°C: 2077 PJ, 100–400°C: 2214 PJ and >400°C: 3859 PJ. The second approach distinguishes between low temperature space heat and hot water (<100°C: 1161 PJ) and four different PH temperature levels with a resulting energy demand of <100°C: 1027 PJ, 100–500°C: 1785 PJ, 500–1000°C: 1679 PJ and >1000°C: 2865 PJ. The high share of high‐temperature heat illustrates the limits to the potential decarbonisation of industrial thermal processes with renewable energy sources such as (non‐concentrating) solar thermal, geothermal or environmental heat. Therefore specific information on required temperature levels is of the essence. This, in turn, points out the relevance of renewable electricity and synthetic fuels based on renewable power for a significant reduction of CO2 emissions from the industry sector in Europe. Considering current data quality, it is recommended to develop a consistent, comprehensive methodology to significantly improve the data basis on industrial heat demand. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Heat pump dryer is a complex system because of the interaction of heat and mass transfer of the working fluids. Since the system cannot be completely close, ambient conditions (temperature and humidity) influence the performance of the system. To investigate the performance of the heat pump dryer thoroughly, simulation models of heat pump dryer components have been developed. The finite-difference method was employed in the simulation to examine the state of the working fluids and heat and mass transfer. The simulation of each component can be used to construct different system configurations the results of which are reported in Part 2. 相似文献
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The Research Laboratory of Kyushu Electric Power Co., Inc. (KEPCO) installed a novel system in March 1992 which is a combination of a super heat pump with about twice the performance of a conventional one and a compact chemical storage-type clathrate cool storage unit. A field test was implemented by integrating these units into an actual air-conditioning system. As a result of the test, system performance was determined and the effectiveness of the system was confirmed. © 1998 Scripta Technica. Heat Trans Jpn Res, 26(6): 410–418, 1997 相似文献
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A simplified model predicting the heat transfer performance of a heat sink base with a high thermal conductivity was developed. Numerical analysis was performed using the commercial software FLUENT. The investigation indicates that for heat sink bases with a high effective thermal conductivity, such as the base embedded with a typical heat pipe, the entire heat sink can be modeled as a flat plate with a uniform temperature and an effective convection heat transfer coefficient. This simplified model can be used to determine the heat transfer performance of a heat sink embedded with a typical heat pipe or vapor chamber. 相似文献
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Lalitha Krishna Nitturi Venkata Kusuma Soumya Kapu Ravi Gugulothu Aparna Kaleru Vinay Vuyyuri Ahmed Farid 《亚洲传热研究》2023,52(6):4422-4449
The thermal performance of energy preservation systems is greatly improved by increasing miniaturization and boosting. These are imaginative (or Promethean) techniques to enhance heat transfer. Enhancement methods of heat transfer draw great attention in front of the industrial sector because of their ability to provide energy savings and raise the economic efficiency of thermal systems. Three techniques these methods are categorized; those are active, passive, and compound. Different types of components are used in passive methods because of the transfer/working fluid flow path to the enhancement of the heat transfer rate. In this article, the subject of the review was the passive heat transfer enhancement methods including inserts (conical strips, winglets, twisted tapes, baffles), porous materials, coil/helical/spiral tubes, rough surfaces (corrugated/ribbed surfaces), extended surfaces (fins) and nanofluids (mono and hybrid nanofluid). Recent passive heat transfer enhancement techniques are studied in this article as they are cost-effective and reliable, and also comparably passive methods do not need any extra power to promote the energy conversion systems' thermal efficiency than active methods. In the passive approaches, various components are applied to the heat transfer/working fluid flow path to improve the heat transfer rate. The passive heat transfer enhancement methods studied in this article include inserts (twisted tapes, conical strips, baffles, winglets), extended surfaces (fins), porous materials, coil/helical/spiral tubes, rough surfaces (corrugated/ribbed surfaces), and nanofluids (mono and hybrid nanofluid). From the pioneers' research work, it is clear that a lower twist ratio and lower pitch, lesser winglet angles can provide more heat transfer rate and a little bit more friction factor. In the case of nanofluids, a little bit of pumping power is enhanced. Finally, heat transfer enhancement is compared with the thermal performance factor, which is more than unity. 相似文献