【作者】 张姝；

【导师】 郑茂余；

【作者基本信息】 哈尔滨工业大学 ， 供热、供燃气、通风及空调工程， 2013， 博士

【摘要】 土壤源热泵作为节能环保的新型空调技术，在国内外被广泛推广和应用。但在严寒地区建筑冷热负荷相差很大，土壤源热泵系统长期运行将导致土壤温度逐年降低，热泵供暖性能也将逐年下降，室温不能满足要求。为此，本文基于季节性土壤蓄热思想，提出了空气源土壤蓄热式热泵(Heat Pump with Air-Source Soil Heat Storage，简称HPASSHS)系统，夏季将自然空气中的热量储存到土壤中，冬季再由热泵从土壤取热供入室内。与太阳能蓄热相比，空气源蓄热设备简单，投资和维护费用较低。在没有集中供热管网，并且不具备足够的屋顶或其它空间安装太阳能集热器时，采用空气源蓄热方法也能实现自然能量的移季利用，为严寒地区应用土壤源热泵供热技术提供了新途径。本文主要从以下几个方面对该系统展开了研究：首先，介绍了HPASSHS系统的主要运行模式及工作原理，建立了系统各传热环节的数学模型。兼顾计算量和准确性，采用当量方形截面单管代替垂直U型埋管，建立了管群土壤换热器的准三维非稳态传热模型，并通过形状因子法得出管壁与土壤的换热边界条件。在上述模型基础上，研究制定了不同运行模式的启停控制条件，为模拟系统动态运行特性奠定基础。其次，在哈尔滨工业大学建立HPASSHS实验系统，并进行了近2年的实验研究。通过实测数据分析空气源土壤蓄热特性、土壤源热泵供热特性和土壤温度变化特性得出：严寒地区空气源季节性土壤蓄热可以有效提高土壤温度，蓄热效果主要受空气温度影响，间歇运行能提高土壤换热器的换热效率。通过模拟结果和实验结果的比较，验证了模型的可靠性和正确性。再次，为哈尔滨节能住宅建筑设计了HPASSHS系统，分别模拟计算了有无空气源蓄热情况下系统连续10年的运行情况。从运行参数、供热效果、性能系数、土壤温度场等方面分析了有蓄热系统的全年运行特性，并将有无蓄热情况下系统的逐年运行性能进行对比得出：严寒地区土壤源热泵系统只有增加季节性土壤蓄热后才能实现土壤温度场的逐年热平衡，并且具备持续的供热能力。另外，模拟分析了蓄热时间、埋管换热面积、热泵容量、室内外风机盘管换热面积对系统运行特性的影响。在此基础上，以费用年值最低为目标对系统进行优化，得到了模拟条件下HPASSHS系统的最优参数组合，并将最优系统同电锅炉供暖、电地热供暖和燃气供暖进行节能性和经济性对比得出，HPASSHS供暖系统在严寒地区应用具有一定优势。最后，将系统拓展应用于寒冷地区，在北京某一节能建筑中设计了HPASSHS系统。夏季采用土壤直接供冷、土壤源热泵供冷和空气源蓄热交替运行，冬季采用土壤源热泵供热。通过模拟计算，分析了HPASSHS系统的全年运行特性，并同传统土壤源热泵系统的运行情况进行对比，结果表明：HPASSHS系统能很好的满足冬夏室温要求，采用土壤直接供冷显著提高了系统供冷性能系数，通过空气源蓄热可使系统全年土壤排热量和取热量平衡，而传统土壤源热泵系统排热量仅为取热量的65%，不利于长期供热。选取两种供热空调方案同HPASSHS系统进行节能性和经济性比较得出，应用HPASSHS系统能明显减少一次能源消耗量，并且经济费用较低。通过模拟和实验研究，证明了严寒和寒冷地区季节性空气源土壤蓄热的可行性，并且HPASSHS系统具有持续高效的供热性能。本文的研究成果将为该系统的应用提供理论基础和技术支持。本课题为“十二五”国家科技支撑计划课题“严寒地区供热系统节能降耗关键技术研究与工程示范”（2011BAJ05B04）的部分内容。更多还原

【Abstract】 The ground-coupled heat pump has been widely popularized and applied athome and abroad as a new air conditioning technology of energy conservation andenvironmental protection. But because the difference between the building heatingload and cooling load in severe cold area, the soil temperature would descend yearby year due to the long-term operation of the ground-coupled heat pump system. Asa result, the heating performance of the heat pump would drop year by year and theindoor temperature can’t meet heating requirement. Therefore, this paper presentedthe heat pump system with air-source soil heat storage (HPASSHS) based on theidea of the seasonal heat storage using the soil as medium. The heat of the naturalair was injected in the soil in summer and was extracted from the soil by the heatpump for space heating in winter. Compared with the solar energy storage, the air-source heat storage has the advantages of simple device and the less cost ofinvestment and maintenance. If there was no the central heating network and no theenough roof space or other space to install the solar collector, the air-source heatstorage could remove the natural energy from summer to winter too， whichprovides a new way for the application of ground-coupled heat pump in severe coldarea. This study is based on the following aspects:Firstly, the operation modes and principles of HPASSHS system wereintroduced, and the numerical model of each heat transfer part in the system wasbuilt. Considering the computational complexity and accuracy, the quasi three-dimensional transient heat transfer model of the multi-pipe ground heat exchangerwas developed using equivalent single pipe with square cross section instead of U-tube, and the heat transfer boundary condition between the equivalent pipe and thesoil was calculated by shape factor method. Based on the above models, the on/offconditions of the different modes were researched and determined, so that thedynamic operation characteristics of HPASSHS system can be simulated.Secondly, the experimental platform of HPASSHS system was set up in theHarbin University of Technology and about two years experiment was performed.The characteristics of the air-source soil heat storage and heating by the ground-coupled heat pump as well as the temperature variation characteristics of the soilwere analyzed base on the measured data. It can be concluded that the soiltemperature could be increased effectively via the air-source soil heat storage, theair temperature was the main influence factor of the heat storage effect, and the heat exchange efficiency of the ground heat exchanger could be improved by theintermittent operation mode. The reliability and validity of the models establishedabove were verified by comparing the simulation results and the experimentalresults.Thirdly, a HPASSHS system was designed for an energy-saving residencebuilding in Harbin, and the10years operation performance of the system with andwithout the air-source heat storage was simulated, respectively. The annualcharacteristics of the system with the air-source heat storage was studied fromoperation parameters, heating effect, coefficient of performance and soiltemperature field and so on, and comparing the system performance with andwithout the heat storage year by year, it was found out that only with the seasonalheat storage could ground-coupled heat pump system realize the soil temperaturefield balance year after year and be sustainable for heating in severe cold area.Fourthly, the impacts on the system operation characteristics caused by themajor parameters including heat storage time, heat exchange area of ground heatexchanger, heat output of heat pump, heat exchange areas of indoor and outdoorfan-coil units were simulated and analyzed, respectively. On the basis ofparameters analysis, the annual minimum cost was taken as the objective tooptimize the system parameters, and the optimal parameter combination of thesystem was gained under the simulation conditions. The HPASSHS system with theoptimal parameter combination was compared with that of electric boiler heating,electric ground heating and gas heating on the sides of energy-saving and economy.The results show that the application of HPASSHS system has a certain advantagein severe cold area.Finally, the HPASSHS system was applied to an energy-saving build ofBeijing in cold area. The soil cooling directly, the cooling by the ground-coupledheat pump and the air-source heat storage operated alternately in summer, and theheating by the ground-coupled heat pump operated in winter. The annual operationcharacteristics of the HPASSHS system were analysed and compared with those ofthe traditional ground-coupled heat pump system by the simulative calculation. Thefollowing conclusions can be drawn: the HPASSHS system can meet the indoortemperature requirement in summer and winter, the cooling coefficient ofperformance of the system rised significantly by the soil cooling directly. Throughthe air-source heat storage, the heat injected into the soil could be equal with theheat exacted from the soil during the HPASSHS system operation. While the heatinjected into the soil was only65%of the heat exacted from the soil during theoperation of the ground-coupled heat pump system, which was not good for thelong-term heating. The energy-saving and economic performances of the HPASSHS system were compared with those of the two heating and air-conditioning plans, theresults indicated that the application of the HPASSHS system in cold area coulddecrease markly the primary energy consumption, and the total cost was less.The simulative and experimental studies in this paper have proved that the air-source seasonal soil heat storage is feasible in severe cold area or cold area and theHPASSHS system has sustainable and efficient heating performance, which canprovide theoretical basis and technical support for the system application.This research topic is a part of the project ’Research on Key Technologies andEngineering Demonstration for Energy Saving and Consumption Reduction of theHeating System in Severe Cold Area’, which is the country ’11th Five-Year Plan’ tosupport science and technology project (No.2011BAJ05B04).更多还原