重力热管在太阳能光电光热利用中的实验和理论研究

发布时间：2018-03-16 04:35

本文选题：太阳能　切入点：热管　出处：《中国科学技术大学》2013年博士论文　论文类型：学位论文

【摘要】：在我国,目前建筑能耗约占全社会总能耗的1/3左右,其中占比最大的建筑能耗是采暖和制冷。与气候条件相近的发达国家相比,我国建筑每平方米采暖能耗约是发达国家的3倍。随着人们物质生活水平的提高,对冬季采暖和夏季制冷的需求会逐渐提高,给我国建筑节能提出了巨大挑战。随着常规能源的日益枯竭和环境问题的日益严峻,太阳能因其清洁、绿色、可再生的特点,引起人们的关注。但是太阳能存在间歇性及能流密度低的特点,规模使用需要很大的面积。在城市,太阳能与建筑具有非常好的结合性,建筑可以为太阳能的应用提供载体,而太阳能可以大大减小建筑的能耗。光伏发电技术和太阳能光热技术作为太阳能的两种主要利用方式,近年来得到了迅速的发展。太阳能光热技术是目前最成熟、普及率最高的太阳能技术,目前最常见的太阳能光热利用方式为太阳能热水、太阳能空气采暖以及太阳能热泵。太阳能光伏光热综合利用(PV/T)技术将太阳能光伏发电技术和太阳能光热技术有机结合,一方面系统可以同时得到电能和热能,提高了太阳能的综合利用率；另一方面,冷却流体可以带走光伏电池的热量,降低电池工作温度,提高电池的光电效率。重力热管是一种具有良好传热性能的元件,依靠自身内部工作液体的相变实现传热。重力热管与普通的太阳能平板集热器或PV/T集热器具有很好的结合性,可以解决普通水冷系统冬季结冰的问题,同时通过热管的间接传热避免了集热器吸热板芯的腐蚀,提高了集热器的寿命；另外热管具有非常好的等温性,与PV/T结合时可以降低光伏电池间的温度差异,提高其光电转化效率。热管与太阳能集热器结合方式主要有两种,一种是将普通的整体式重力热管(简称整体热管)与太阳能集热器的结合；另外一种是重力环形热管(简称环形热管)的改造,将整个集热器作为环形热管的蒸发段,将水箱里面的盘管作为冷凝段。环形热管的蒸发段和冷凝段分离的特性使其与建筑具有非常好的结合性；同时环形热管和热泵也具有非常好的结合性,二者可以采用相同的循环工质,可以采用相同的集热器-蒸发器,可以大大简化系统的结构。本文将整体热管和环形热管与普通的太阳能集热器和PV/T集热器结合,提出了整体热管式PV/T系统、环形热管式太阳能光热系统、环形热管式PV/T系统；同时将环形热管与光伏-太阳能热泵系统结合,提出了光伏-太阳能环形热管／热泵复合系统(PV-SALHP/HP)。环形热管可以减小热泵系统的能耗,热泵可以弥补太阳能间歇性的特点,通过对热管运行模式和热泵运行模式的切换可以提高设备利用率和太阳能利用率。本文的研究工作主要包括以下几个方面： (1)设计和搭建了整体热管式PV/T系统,并对系统在有、无玻璃盖板下的综合性能进行了比较。结果显示,有玻璃盖板时系统日平均光热效率为41.30%,日平均光电效率为9.42%,日平均(?)效率为6.87%。无盖板时系统的日平均光热效率为37.16%,日平均光电效率11.51%,日平均(?)效率为8.01%。同时建立了整体热管式PV/T系统的动态数学模型,并与实验结果进行了对比,结果表明二者具有很好的一致性。 (2)设计和搭建了环形热管式PV/T系统和普通水冷型PV/T系统的对比实验台,并对二者的综合性能进行了比较分析。结果表明,环形热管式PV/T系统具有较低的光热效率,较高的光电效率,但是二者具有相近的炯效率。 (3)设计和搭建了环形热管式太阳能光热系统,对不同充注量下系统的热性能进行了长期的室外测试,并通过三次线性插值的方式求解出了系统的最佳充注量。结果显示,不同充注量下,集热器和系统的热性能拟合都呈现相同的趋势,为先增大后减小,而热损都是逐渐减小；系统最佳的体积充注量为36.6%。 (4)设计和搭建了动力环形热管式太阳能光热系统,并对50%体积充注量下系统的热性能进行了实验研究。结果表明拟合后的集热器和系统的热性能与普通的水冷型光热系统性能接近,拟合系统日平均热效率为51.4%。 (5)建立了直膨式光伏-太阳能热泵系统的动态数学模型,并与实验结果进行了验证。结果表明,对压缩机功率及水箱温度的模拟具有较好的一致性；由于压缩机模型中未考虑两相的影响,光电效率只考虑了温度对效率的影响,模拟的压缩机进口压力和光电效率与实验结果具有较大的误差。 (6)设计和搭建了光伏-太阳能环形热管／热泵复合系统(PV-SALHP/HP),并对热管单独运行模式下和热泵运行模式下系统的性能进行了实验研究。研究结果表明,热管单独运行模式下,系统的日平均热效率为43.6%,日平均光电效率为11.3%；热泵单独运行模型,系统的日平均COP为3.66,日平均光电效率为12.1%,日平均光热效率可达57.5%。
[Abstract]:In our country, the current building energy consumption accounts for about 1/3 of the total energy consumption of the whole society, which is the largest proportion of building energy consumption for heating and cooling. Compared to developed countries with similar climate conditions, our country building heating energy consumption per square meter is about 3 times that of developed countries. As the living level improved, the the winter heating and summer cooling demand will gradually increase, has posed great challenges to China's building energy efficiency.
With the increasing depletion of conventional energy and environmental problems become more and more serious, solar energy for its clean, green, renewable characteristics, cause the attention of people. But there are intermittent solar and energy flow characteristics of low density, the scale of use requires a lot of area in the city, the sun can combine well with the building, the building can be to provide support for the use of solar energy and solar energy can greatly reduce the energy consumption of the building. The photovoltaic technology and solar thermal technology as the two main use of solar, in recent years has been rapid development. Solar thermal technology is the most mature, the highest penetration rate of solar technology, the most common use of solar energy as the solar water heater, solar air heating and solar energy heat pump. Solar photovoltaic (PV/T) solar thermal utilization technology of the solar photovoltaic power generation technology Combined with solar thermal technology, on the one hand, the system can get power and heat at the same time, improve the comprehensive utilization of solar energy. On the other hand, cooling fluid can take away the heat of photovoltaic cells, reduce the working temperature of batteries, and improve the photoelectric efficiency of batteries.
The gravity heat pipe is provided with a good heat transfer performance of the components, rely on internal work to achieve the liquid phase change heat transfer. The gravity heat pipe collector with a combination of good and ordinary flat plate solar collector or PV/T, can solve the problem of the ordinary winter ice water cooling system, at the same time through indirect heat pipes to avoid the corrosion of the collector absorber plate core, improve the collector's life; in addition the isothermal heat pipe has very good, you can combine with PV/T to reduce the temperature difference between the photovoltaic cell, improve the photoelectric conversion efficiency. The heat pipe and the solar collector combination mainly has two kinds, one is the integrated gravity heat pipe (referred to as the common integrated heat pipe heat exchanger) combined with solar set; another is the gravity loop heat pipe (the circular heat pipe) transformation, the collector as the evaporation section of loop heat pipe, the water tank The inside of the coil as the condensing section. The evaporation section and the condensation section of the separation characteristics of annular heat pipe combined well with the building with circular heat pipe and heat pump; at the same time also has a very good combination of the two can use the same refrigerant, can use Collector - the same evaporator. Can greatly simplify the structure of the system.
The whole heat pipe and annular heat pipe heat collector with solar collector and PV/T tube type PV/T system is proposed. The overall heat, the annular heat pipe type solar thermal system, the annular heat pipe PV/T system; combining the circular heat pipe and photovoltaic solar assisted heat pump system, the PV - the annular solar heat pipe / heat pump system (PV-SALHP/HP). The annular heat pipe can reduce the energy consumption of heat pump system, heat pump can compensate for the intermittent characteristics of solar energy through the heat pipe, switching operation mode and operation mode of heat pump can improve the utilization ratio and the utilization of solar energy equipment.
The research work of this paper mainly includes the following aspects:
(1) design and build the integrated heat pipe type PV/T system, and the system in a comprehensive performance, no glass cover were compared. The results showed that the glass cover system on average thermal efficiency was 41.30%, the average optical efficiency is 9.42%, the average daily efficiency of 6.87%. (?) without cover the average thermal efficiency of 37.16%, the average optical efficiency of 11.51%, the average daily efficiency of 8.01%. (?) and establishes a mathematical model of the whole heat pipe PV/T system, and compared with the experimental results, the results showed that the two are in good agreement.
(2) contrast test rig was designed and built an annular heat pipe type water-cooled type ordinary PV/T system and PV/T system, and the comprehensive performance of the two carried out a comparative analysis. The results show that it has low thermal efficiency of annular heat pipe PV/T system, photoelectric efficiency is higher, but the two have similar Jiong efficiency.
(3) design and build a circular heat pipe type solar thermal system, the thermal performance of different charge system of long-term outdoor tests, and by three linear interpolation method to calculate the optimal charge system. The results showed that the different filling quantity, the thermal performance of the collector fitting device and system are showed the same trend, firstly increased and then decreased, and the heat loss is gradually decreased; the volume filling quantity of the best system for 36.6%.
(4) the design and tube type solar thermal system to build a dynamic circular heat, and thermal properties of the 50% volume charge system were studied. The results show that the thermal performance of the collector to the fitting and the system with ordinary water-cooling thermal system performance, system fitting the average thermal efficiency of 51.4%.
(5) to establish the dynamic mathematical model of photovoltaic direct expansion solar assisted heat pump system, and verified with the experimental results. The results show that the simulation of the compressor power and the temperature of the water tank has good consistency; without considering the influence of two-phase compressor model, the photoelectric efficiency only considers the influence of temperature on the efficiency of the the compressor inlet pressure, simulation and experimental results of photoelectric efficiency and has a large error.
(6) design and build a photovoltaic solar - circular heat pipe / heat pump system (PV-SALHP/HP), and the performance of the heat pipe separate operation mode and operation mode of heat pump system were studied. The results show that the heat pipe separate operation mode, on the flat system are the thermal efficiency is 43.6%, Japan the average optical efficiency is 11.3%; heat pump separate operation model, COP system on average was 3.66, the average optical efficiency is 12.1%, the average thermal efficiency can reach 57.5%.

【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU18;TK519

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