太阳能辅助二氧化碳热泵性能和应用研究

发布时间：2018-01-31 11:47

本文关键词： 二氧化碳制冷自然工质太阳能制冷太阳能供暖零能耗建筑　出处：《上海交通大学》2013年博士论文　论文类型：学位论文

【摘要】：太阳能热驱动制冷技术，可转化夏季建筑物立面所接受的太阳辐射为所需冷量，在能源转换与利用层面具有合理性。然而，太阳能能流密度低且不稳定，以太阳能驱动的小型制冷机制取的冷冻水温度较高，不适宜直接输入室内末端，进行供冷。另一方面，太阳能辅助热泵进行供暖和生活热水联合供给的技术已经相对成熟，此类系统不能以高效节能的形式满足建筑制冷需求，且夏季太阳能集热环路存在过热。因此，集成太阳能制冷技术，最终形成在全年尺度内满足建筑制冷、供暖和生活热水综合需求的设备，是一个重要的研究方向。针对以上问题，本研究尝试开发一种太阳能辅助过冷的二氧化碳混合热泵（冷热兼供型），其通过太阳能驱动小型吸收机对二氧化碳机组进行过冷却，从而强化其制冷性能，使整机的冷热输出与建筑负荷更为匹配。本研究首先建立了太阳能辅助二氧化碳跨临界制冷循环的数学模型，明确了过冷却热力过程在超临界循环中的特性，比较了过冷在二氧化碳超临界循环和合成制冷剂亚临界循环中的异同，且通过稳态模拟量化节能率，明确过冷却对性能的促进。其后，从空调工况应用角度，分析了通过太阳能制冷实现过冷强化的可行性并预测了太阳能吸收式制冷与常规二氧化碳压缩式制冷两项技术结合后的整机性能。模拟结果显示，当环境温度为28oC时，过冷过程的增加可使循环COP达到4.0，相较原基本循环，制冷性能可以提升45.5%。此外，如果以太阳能吸收式制冷来实现过冷却过程，则当驱动温度为90oC时，可再生能源转化的辅助冷量占总冷量的比例为22%，当驱动温度为94oC时，该比例可升至33%。在热力学分析的基础上，开发了试验样机并分别搭建了制冷和供暖试验系统，进行了现场性能测试。实验测量了开发机组在制冷工况下，分别采用混合模式（含太阳能辅助过冷）和独立模式（普通二氧化碳制冷）的机组性能。结果显示，混合模式下，室外温度约为28.0oC时，制冷COP约为2.32。主机供暖性能测试结果显示，室外温度为10.4oC时，制热COP为2.60。因机组集成了太阳能集热和储存环路等，故影响整机性能的参数较常规热泵机组更多，特别是需考虑太阳能辐照强度等因素对机组性能的影响。故在单机性能研究的基础上，对太阳能辅助二氧化碳压缩式制冷系统进行了性能分析。研究从单一针对开发机组，扩展到包含有太阳能集热器、水箱、主机和建筑的供能系统。研究基于经过试验验证的系统模型，通过动态模拟，对影响系统性能的参数进行了分析并量化了影响程度，同时通过模拟比较了设计的制冷系统与常规制冷系统的性能。在供热工况下，太阳能辅助设备与压缩式主机的结合方式与制冷工况下不同，并非采用机内集成模式，而是作为双热源并联供给至室内末端。因此，结合供暖系统的形式，对系统重要参数，如集热器面积、水箱体积、室内负荷和控制条件等分别进行了单参数（变量）的影响程度分析。在此基础上，，通过敏感性分析，确定了不同影响参数的权重，据此，选取了主要影响参数进行了以成本为目标函数的多参数同步优化模拟。并通过太阳能保证率、主机性能等性能指标对优化后的系统进行了性能分析与评价。最后，以零能耗为核心设计和评价目标，结合一栋实际建筑，讨论了以开发主机为核心的建筑能源系统实际应用。该能源系统可在全年尺度内满足90m2公寓内的制冷、采暖和生活热水需求，同时，通过太阳能光伏发电补充实现年净能耗为零。在对设计要素进行阐述的基础上，进行了能源系统整体性能分析，该分析不仅量化了含建筑在内的整体系统各部分能耗，而且比较了供需以验证设计目标。除零能耗设计指标外，对系统在舒适性等指标也进行了评价。
[Abstract]:Solar driven refrigeration technology, solar radiation can be transformed into the summer facade and accepted as the required cooling capacity, the energy conversion and utilization level is reasonable. However, the solar energy density is low and unstable, chilled water temperature is higher in small refrigeration system driven by solar energy is not suitable for direct input from the indoor terminal, for for the cold. On the other hand, the solar assisted heat pump combined heating and hot water supply technology is relatively mature, this kind of system can not meet the demand of building cooling with high efficiency and energy saving, and summer solar heat loop overheating. Therefore, the integration of solar refrigeration technology, finally formed in the annual scale meet the building cooling, heating water and water requirement of equipment, is an important research direction. In view of the above problems, this study attempts to develop a solar assisted cold two Carbon dioxide hybrid heat pump (cold and heat supply type), which is driven by solar energy and small absorption machine, is used to cool the CO2 unit, so as to enhance its refrigeration performance, and make the cold and heat output of the whole machine match the building load better.
This research has established the mathematical model of solar assisted carbon dioxide transcritical refrigeration cycle, the cooling process in the super critical thermal characteristics in the circulation, compared the supercooling in ultra supercritical circulating and synthesis of carbon dioxide between refrigerant subcritical cycle, and through quantitative simulation of the steady rate of energy saving, clear cooling promote on performance. Then, from the angle of application condition, through the realization of the feasibility of solar refrigeration and enhanced cooling and forecast the performance of compression refrigeration technology in two after the combination of solar absorption refrigeration and conventional carbon dioxide. The simulation results show that when the ambient temperature is 28oC, increasing the cooling process of the circulating COP reached 4 compared to the original basic cycle, can improve the refrigeration performance of 45.5%. in addition, if the solar absorption refrigeration to achieve the cooling process, when the driving temperature is 90oC At the time, the proportion of the auxiliary cooling capacity of the renewable energy conversion is 22%. When the driving temperature is 94oC, the ratio can rise to 33%.
Based on the thermodynamic analysis, the development of the experimental prototype were built and the cooling and heating test system, on-site performance testing. Experimental measurement of the development unit in cooling conditions, using mixed mode (including solar assisted cold) and independent mode (ordinary carbon dioxide refrigeration) of the unit performance. The results show that mixed mode, the outdoor temperature is about 28.0oC, about COP refrigeration heating performance test results of 2.32. display, the outdoor temperature is 10.4oC, heating for 2.60. COP
Because the unit integrates solar heat collection and storage ring, the impact of the performance parameters more than conventional heat pump units, especially the need to consider the factors of solar radiation intensity effects on the performance of the unit. It is based on the single performance study, two of the solar assisted carbon dioxide compression refrigeration system is analyzed from the research. A single unit for the development, expand to include a solar collector, water tank, and the construction for the host system can through the system. Based on the model test, through dynamic simulation, parameters affecting the system performance are analyzed and quantify the degree of influence, and compare the performance of refrigeration system design and conventional refrigeration system through the simulation.
In the heating conditions, the solar energy auxiliary equipment and compression type host combination with different cooling conditions, is not used in the integrated model, but as the two heat sources parallel supply to the indoor terminal. Therefore, combined with the heating system, the important system parameters, such as the collector area, tank volume, indoor load and control conditions were investigated by single parameter analysis (variable) of the impact. On this basis, through sensitivity analysis, to determine the weights of different parameters, accordingly, select the main parameters of synchronous simulation and Optimization Based on cost parameters of the objective function. And the solar fraction, the performance index of host performance analysis and evaluation on the performance of the optimized system.
Finally, the zero energy consumption as the core design and evaluation, combined with a practical construction, discusses the practical application of building energy system for the development of the host as the core. The energy system in the annual scale in 90m2 meet in the apartment of refrigeration, heating and hot water demand, at the same time, through the implementation of solar photovoltaic power generation of net energy consumption zero. Based on the design elements, the overall performance analysis of energy system, energy consumption of each part of the whole system of the quantitative analysis not only with building, and compared the supply and demand in order to verify the design goals. In addition to zero energy design index, the system on comfort index was also evaluated.

【学位授予单位】：上海交通大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU83

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