【作者】 袁磊；

【导师】 余南阳；

【作者基本信息】 西南交通大学 ， 供热、供燃气、通风及空调工程， 2013， 博士

【摘要】 目前河西走廊地区采暖方式以燃煤、燃气锅炉为主,这种采暖方式不仅能耗高而且污染严重,从而节能、环保的采暖方式成为该地区一个亟需解决的问题。本文从河西走廊地区的气候特征和能源结构特点综合考虑,基于改进型生命周期评价方法,建立了河西走廊地区采暖形式全生命周期评价指标体系,并利用优化算法,验证了太阳能和CO2空气源热泵联合采暖系统是可应用于该地区的最优采暖形式。采用实验和仿真计算相结合的方法对太阳能和CO2空气源热泵联合采暖系统进行了详细、系统的研究,其研究成果可以为太阳能和C02空气源热泵联合采暖系统在河西走廊及气候条件相似地区的应用提供理论依据和技术参考。本文分别开展了太阳能集热采暖系统、C02空气源热泵采暖系统的实验研究。实验结果表明：大流量造成集热器出口温度较低,温差变大,但不同流量的进出口平均温度基本一致。通过动态测试方法,可计算得出所用集热器太阳能保证率,并线性拟合得到集热器瞬时效率公式：77=0.627-0.35T*。CO2空气源热泵实验结果表明：气体冷却器水侧的进水温度、进水流量和蒸发器空气侧的室外温度、风速是影响该系统COP的主要因素,并进一步得到室外温度在-25℃--15℃时,CO2空气源热泵COP在2-3之间。基于微元法建立了太阳能和CO2空气源热泵联合采暖系统的数学模型,并应用TRNSYS软件建立了仿真计算模型,实现了系统各模型耦合求解。同时,对模拟数据和实验数据进行对比,验证了仿真模型的可靠性。分析了CO2空气源热泵中气体冷却器、蒸发器和回热器在低温条件下对机组性能的影响。气体冷却器对机组性能的影响为：随气体冷却器进水温度的升高,机组制热量不断下降。另外,气体冷却器进水流量的增大能够提高机组的性能系数,但同时也会减小出水温度,所以应该根据实际需求确定进水流量。由蒸发器空气侧室外温度和空气流量对机组性能的影响可知,机组COP随着室外温度的下降而下降,而空气流量的增加提高了机组COP,但空气流量的不断增大,对COP的影响却越来越小。因此,在实际应用中当室外温度较低时,为了使机组COP保持在较高水平,可通过调节空气流量等方法来实现。研究还表明：带回热器的机组平均COP比无回热器提高了5%。本文基于典型晴天、多云天和阴天三种工况对太阳能和C02空气源热泵联合采暖系统影响因素进行了分析。其结果表明：三种工况下均呈现出机组COP随集热器面积的增大逐渐增大的趋势,并且同一集热器面积下,机组COP随日间太阳辐射的增强逐渐增大。如,当集热器面积为600m2时,和集热器面积为Om2相比,CO2空气源热泵节能率提高了24.9%；另外,典型晴天和多云天工况相比,节能率提高了19.2%。在能耗分析中,根据能耗分析方法定义了太阳能相应产电效率ηsegp及集热器综合效率,通过综合效率对集热面积进行了优化,得出该地区最佳采暖季太阳能保证率27.7%。在此基础上给出了联合采暖系统应用于实际工程时,集热面积与C02空气源热泵机组制热量之间的关系式通过确定系统的控制目标,提出相应监测参数、探讨太阳能和CO2空气源热泵联合采暖系统的7种运行模式及各种运行模式的转换条件,从而建立了一套适用于太阳能和C02空气源热泵联合采暖系统的逻辑控制策略,并通过案例分析验证了控制策略的可靠性。更多还原

【Abstract】 Currently, the heating system gives first place to the cola-fired and gas-fired boiler system in Hexi Corridor, which is of high energy consumption and serious pollution; therefore, an energy-saving, environmentally-friendly heating system is a priority of great concern and to be addressed. Based on the improved life cycle assessment method, this paper has, taking into overall consideration the climatic characteristics and energy structure features of Hexi Corridor, established a life cycle assessment index system of heating system for Hexi Corridor, based on which optimized algorithm is used to obtain the optimum heating system suitable for Hexi Corridor—solar energy and CO2air-source heat pump combined heating system. Experiment and simulated computation models are integrated to make detailed, in-depth study on the system. The study results may provide theoretical basis and technical reference for the design of solar and CO2air-source heat pump combined heating system in Hexi Corridor.In this paper, an experimental research is performed on the solar collector heating system and the CO2air-source heat pump heating system respectively. The results indicate that the law is that the heat collector outlet is low in temperature and has a large temperature difference caused by a large flow rate, but the mean temperature of inlet and outlet is the same under the different flow rates. Using the dynamic measurement method, the solar fraction of the used heat collector can be calculat, and the linear fit formula for instantaneous efficiency of the used heat collector is η=0.627-0.357*. The experimental results of CO2air-source heat pump indicate that water inlet temperature and flow at water side of the gas cooler as well as outdoor temperature and air flow at air side of the evaporator are primary factors to affect the system COP, and the unit COP is ranging from2to3when the CO2air-source heat pump is in a low-temperature condition of-25℃～15℃.In this paper, the mathematical model and simulated calculation model are established for the solar energy and CO2air-source heat pump combined heating system based on the infinitesimal method, and TRNSYS is applied to make coupling solutions of all models of the system. Furthermore, the simulation and experimental data is compared to verify the reliability of the simulated model.The impact of the unit performance on the gas cooler, evaporator and heat regenerator of the CO2air-source heat pump under low temperature is analyzed The impact of the unit performance on the gas cooler of the results indicate that, while under a low temperature, the heating capacity would be continuous reduced with the increase of inlet water temperature of the gas cooler. In addition, increased water inflow of the gas cooler can improve the coefficient of performance (COP) of the unit, but also can reduce the water outflow temperature, thus, water inflow shall be chosen properly according to actual demands. Judging from the impacts of the outdoor temperature and air flow at air side of the evaporator on the unit performance, the unit COP decreases with the drop of outdoor temperature; the increased air flow may improve the unit COP, yet the increasing air flow has less and less impacts on the COP. Therefore, in actual application when outdoor temperature is in a low-temperature condition, in order to make the unit COP is maintained at a higher level, may be by adjusting the air flow and other methods to achieve. The study results on heat regenerator show that the average COP of units with heat regenerators are5%higher than those without heat regenerators;This paper also makes simulation study on operating characteristics of the solar and CO2air-source heat pump combined heating system based on typical clear day, cloudy day and cloudy three conditions, and the impact of collector area on the performance of CO2air-source heat pump is analyzed. The results indicate that in three working conditions, the COP of the unit would gradually increase with the increase of collector area. Meanwhile, the COP would gradually increase with the increase of solar radiation. For instance, when the collector area is600m2, of which, the energy saving rate of the CO2air source heat pump is24.9%higher than that when the collector area Om2; the energy saving rate in a typical cloudy day is19.2%lower than that in the sunny day. Through the analysis of energy consumption, the solar equivalent generation power efficiency ηsegp and the comprehensive efficiency of collector is defineded. The collector area is optimized through the comprehensive efficiency, thus obtaining the optimal the solar fraction of this area in the heating season is27.7%. Based on the optimal the solar fraction, the relation expression between the collector area and the heating capacity of CO2air-source heat pump unit, when the combined heating system is used in actual engineering, isThe control strategy of the solar energy and CO2air-source heat pump combined heating system is established. Propose the monitoring parameters through determining the control objective of the system, comprehensively introduce the seven operation modes of the solar energy and CO2air-source heat pump combined heating system under the optimal operation conditions, introduce the converting conditions of each operation mode based on the control principle by making examples, and finally determine the control strategy as well as verify its reliability through case analysis.更多还原