槽式太阳能集热器传热模型及性能分析

槽式太阳能集热器一维和二维传热数学模型是一组非线性代数方程,为改进求解的稳定性和计算精度,将槽式太阳能集热器一维和二维传热模型的求解看作有约束优化问题,建立了集热器传热过程求解的有约束优化数学模型,应用MATLAB软件优化函数fmincon进行求解。分析了传热流体入口温度及太阳能辐射热流密度变化对集热器性能的影响。采用fmincon函数求解集热器传热过程,计算速度快,计算过程稳定。分析表明,传热流体温度变化对集热器效率的影响大于太阳能辐射热流密度对集热器效率的影响。     

瓦型集热器综述

对国内和国际上关于瓦型太阳能集热器和太阳能集热瓦的研究进行了大量的文献调研工作,本文将对瓦型集热器和太阳能集热瓦作一个综述性的介绍.在文献调研的基础上,针对黄山地区徽派建筑的风格特点,设计出一种与徽派建筑相匹配的新型瓦型太阳能双效集热器和一种有利于标准化建设的太阳能集热屋顶,实现太阳能集热装置与徽派建筑一体化的目的.     

太阳能集热器驱动的吸收式制冷系统性能分析

为了合理利用太阳能,增强制冷系统的季节适应性,提出一种中温太阳能驱动的氨水吸收式制冷系统。以抛物面槽式太阳能集热器(parabolic trough solar collector, PTSC)驱动的氨水单效吸收式制冷系统为对象,根据热力学定律和能量平衡方程,在工程求解器(engineering equation solver, EES)下,分别建立太阳能集热器模型和制冷系统模型,并对系统的关键参数进行计算。从制冷量、精馏热和系统能效比(COP)三方面分析了系统高压、系统低压、蒸发器出口温度和精馏器出口质量分数对系统的影响。结果表明:制冷量随系统低压的升高而降低;精馏热及COP随系统低压的升高而增加;蒸发器的出口温度升高时,制冷量和COP均有增加;当精馏器出口氨的质量分数为0.977~0.999, COP在氨水质量分数为0.992时出现最大值。研究结果为太阳能驱动单级吸收式制冷循环的可行性提供了理论依据。     

折流板型太阳能空气集热器数值优化

通过数值求解基于雷诺时均的三维定常粘性N-S方程及能量方程,改变结构、特性及运行参数,对折流板型太阳能空气集热器进行了数值优化,模拟结果表明：折流板的引入可有效提高集热效率,同时对于特定尺度的折流板集热器,存在最优分割腔数;增加集热器上部盖板的保温能力可有效提高集热效率,实际使用中推荐保温能力较好的双玻盖板或适当增加空气间层厚度;集热器的热损失以对流散热占主导,辐射散热为次要因素;运行参数如气温、日照强度等对集热器进出口温升影响显著,但对集热效率影响较小。     

Thermal performance of solar air collector with transparent honeycomb made of glass tube

Transparent honeycomb structure with thin-walled glass tube as the honeycomb unit is designed and applied to a flat-plate solar air collector. Experiments are performed for solar collectors with six different honeycomb sizes. The emphasis is to study the effects of diameter and aspect ratio of the honeycomb unit on the transmittance and efficiency of the solar collector. It is shown that for the same diameter but different aspect ratios, there are large temperature differences between the collector’s exits;...     

黄山地区徽派建筑与百叶型集热墙研究

从分析黄山市的地域特性、气候特点和该地区的徽派建筑特色出发,从徽派建筑的传承和发展角度,结合新能源太阳能技术,建筑节能理念,利用徽派建筑大面积的南立墙面和遮雨（阳）檐的遮挡效果,将百叶型太阳能集热墙和遮雨（阳）檐相结合,在冬季和夏季时不同的工作模式下,能增加冬季时的采暖效果和夏季的通风效果,加强徽派建筑特色的保护和传承.     

平板型太阳能双效集热器空气集热性能的理论分析

针对两种不同结构的双效太阳能平板集热器,建立上流道和双流道两种结构双效集热器的空气集热模型,以热力学第一定律和第二定律为基础,综合考虑空气集热效率和净有效能的情况下,研究了两种空气流道结构条件下,流道高度对集热器性能的影响.结果表明,对于上流道结构的空气集热器,流道高度为15mm时,热效率和净有效能均最高,15mm是上流道式集热器的适宜流道高度;对于双流道结构的空气集热器,上、下流道高度均为15mm至25mm间时热效率和获得的净有效能最高.     

制冷剂工质裸板太阳能集热器热性能模拟

为了对裸板太阳能集热器进行热性能分析及优化设计,建立其分布参数均相流动数学模型.该模型基于直膨式太阳能热泵热水系统,利用换热管内、外换热方程和热平衡方程,对过热区和两相区按焓差均分进行划分,采用二分法以换热管长为迭代判据进行求解.通过理论计算分析集热管内制冷剂状态变化和结构参数、运行参数、环境参数对集热器集热效率的影响.模拟结果表明:两相区制冷剂干度变化近似为线性;室外环境温度升高和集热板厚度增大可显著提高集热器集热效率;太阳辐射强度、水箱水温和集热管间距增大使集热效率降低;增加集热管内径对提高集热效率作用不大.     

平板式钢管混凝土太阳能聚热器的水温曲线

首先介绍了平板式钢管混凝土太阳能聚热器的构造,然后对其热性能进行了分析,最后根据测试结果绘出了水温曲线.此种聚热器夏季可提供淋浴用水,冬季可对室内进行供暖.     

A design method and numerical study for a new type parabolic trough solar collector with uniform solar flux distribution

The non-uniform concentrated solar flux distribution on the outer surface of the absorber tube can lead to large circumferential temperature difference and high local temperature of the absorber tube wall,which is one of the primary causes of parabolic trough solar receiver(PTR)failures.In this paper,a secondary reflector used as a homogenizing reflector(HR)in a conventional parabolic trough solar collector(PTSC)was recommended to homogenize the solar flux distribution and thus increase the reliability of the PTR.The design method of this new type PTSC with a HR was also proposed.Meanwhile,the concentrated solar flux distribution was calculated by adopting the Monte Carlo ray-trace(MCRT)method.Then,the coupled heat transfer process within the PTR was simulated by treating the solar flux calculated by the MCRT method as the heat flux boundary condition for the finite volume method model.The solar flux distribution on the outer surface of the absorber tube,the temperature field of the absorber tube wall,and the collector efficiency were analyzed in detail.It was revealed that the absorber tube could almost be heated uniformly in the PTSC with a HR.As a result,the circumferential temperature difference and the maximum temperature could be reduced significantly,while the efficiency tended to decrease slightly due to the inevitably increased optical loss.Under the conditions studied in this paper,although the collector efficiency decreased by about 4%,the circumferential temperature difference was reduced from about 25 to 3 K and the maximum temperature was reduced from667 to 661 K.     

两种太阳能空气集热器性能比较研究

为了研究平板式太阳能空气集热器的集热效率,对不同形状吸热板的集热效率进行了动态测试.结果表明,使用穿孔吸热板的平板太阳能空气集热器的出风口温度和集热效率均明显高于使用无孔波纹吸热板的太阳能空气集热器.该集热器可增加对太阳辐射热能的吸收,加强吸热体和空气的对流换热.     

寒冷地区农村组合式太阳房的节能性分析

通过对寒冷地区农村住宅的实地考察,根据当地的气候特点、住宅现状以及农民的生活习惯,提出适合该地区环境特点的一种低造价的被动式太阳房形式——"直接受益式+附加阳光间式"组合式太阳房.以吉林省农村住宅为例,计算该组合式太阳房与当地现有住宅在采暖期的采暖能耗.通过对比分析得出,该组合式太阳房的节能率为70%以上,节能效果显著,满足可持续发展的要求,具有推广的价值.     

太阳能热水器水箱容积与集热面积的合理配比

通过对影响水箱容积与集热面积合理配比取值若干问题的分析，提出了应根据设备投资、热水器服务地区的气象条件等因素，来考虑太阳能热水器水箱容积与集热面积合理配比取值的观点，给出了以最大收益为目标函数的计算公式，利用该公式可得到各种气象条件下的最优容积面积比参数。     

Numerical analysis of flow and heat transfer behavior in fin-tube flat-plate solar collector

There has been a lot of concern on the cost of en-ergy during the past two decades. The risk and realityof environmental degradation have become more appar-ent. The growing evidence of environmental problems iscaused by a combination of several factors si…     

与建筑一体化太阳能双效集热招系统夏季工作性能的影响

作为一种新型的太用能光热建筑一体化系统,与建筑一体化太阳能双效集热器系统具有2种工作模式：在冬季的被动采暖工作模式和在其他无需供暖的时期的集热水工作模式。针对系统以自然循环方式工作的集热水工作模式,进一步建立了系统房间带窗结构时的理论计算模型。以设计的虚拟房间为对象,通过理论分析,研究了在夏季季节运行时,系统的工作水量和背板保温层设计对系统集热水性能和对建筑的热影响的不同情况。结果显示：对于系统设计来说,背板保温层的适宜设计厚度约在0．05m,工作水量在夏季运行时的适宜量约是40～50kg／m2;系统在夏季工作时可以在一定程度上降低房间的冷负荷,不会造成传统被动采暖系统常遇到的夏季建筑过热问题。     

太阳能温差发电系统的性能

建立太阳能温差发电系统的数学模型,利用温差发电技术将太阳能直接转化为电能.考虑冷却系统的功耗,分析聚焦倍率以及冷却水流量对太阳能温差发电系统的净输出功率与净发电效率的影响.结果表明,存在最优的冷却水流量及最优的聚焦倍率,使得系统发电性能最大,最大净输出功率与净发电效率分别为15.86 W和5.61%;对温差发电器热端进行必要的保温,能够提高系统的发电性能.     

Characteristics of the transient thermal load and deformation of the evacuated receiver in solar parabolic trough collector

As a core element in solar parabolic trough collector, the evaluated receiver often runs under severe thermal conditions. Worse still, the transient thermal load is more likely to cause structural deformation and damage. This work develops an efficient transient multi-level multi-dimensional(M~2) analysis method to address photo-thermal-elastic problems, thereby estimating transient thermal load and deformation for the receiver:(i) one-dimensional(1-D) thermo-hydraulic model is adopted to determine the transient thermo-hydraulic state,(ii) 3-D finite volume method(FVM) model for the receiver tube is established to obtain the real-time temperature distribution,(iii) 3-D finite element method(FEM) model is employed to make thermoelastic analysis. Based on this M~2 method, the typical transient cases are conducted in cold-start, disturbed-operation and regulatedprocess. Three indicators(average temperature of the wall(ATW), radial temperature difference(RTD), circumferential temperature difference(CTD)) are defined for overall analysis of the receiver thermal load. It is found that in the transient process,receivers face response delay and endure significant thermal load fluctuation. The response time for a single HCE(heat collecting element) under lower mass flow rate(1.5 kg s~(-1)) could sustain 280 s. During the cold-start stage(DNI=200 W m~(-2) to 800 W m~(-2)), the maximum value of CTD in receiver is as high as 11.67℃, corresponding to a maximum deflection of 1.05 cm.When the mass flow rate decreases sharply by 80%, the CTD reaches 33.04℃, causing a 2.06-cm deflection. It should be pointed out that in the cold-start stage and the lower mass flow rate operation for solar parabolic trough collector, alleviating the transient thermal load and deformation is of importance for safely and efficiently running evaluated receiver.     

用于槽式太阳能电站的热管式集热器开发及传热分析

综合利用槽式聚焦型聚光镜和热管式真空管接收器的优越性,开发了一种槽式热管式太阳能集热器,给出了此新型集热器的结构设计。从光学和传热两方面考虑,建立了槽式热管式集热器集热模型,并建立了热管半壁受热的传热模型。对该集热器进行了传热分析和计算,推导出了槽式热管式集热器的集热效率计算公式,与实验室开发的CPC集热器进行了比较。结果表明,槽式热管式集热器效率远高于CPC集热器,最高可达75%,在工作流体温度上升至350℃以上时,因部分流体汽化使集热效率略微降低,仍可保持在70%左右。     

Experimental investigations on the heat transfer characteristics of micro heat pipe array applied to flat plate solar collector

This paper introduces a novel flat plate solar collector(FPC) using micro heat pipe array(MHPA) as a key element.To analyze the thermal transfer behavior of flat plate solar collector with micro heat pipe array(MHPA-FPC),an indoor experiment for thermal transfer characteristic of MHPA applied to FPC was conducted by using an electrical heating film to simulate the solar radiation.Different cooling water flow rates,cooling water temperatures,slopes,and contact thermal resistances between the condenser of MHPA and the heat exchanger were tested at different heating powers.The experimental results indicate that MHPA-FPC exhibits the enhanced heat transfer capability with increased cooling water flow rate and temperature.Total thermal resistance has a maximum decline of approximately 10% when the flow rate increases from 180 to 360 L h 1 and 38% when the cooling water temperature increases from 20℃ to 40℃.When the inclination angle of MHPA-FPC exceeds 30°,the slope change has a negligible effect on the heat transfer performance of MHPA-FPC.In addition,contact thermal resistance significantly affects the heat transfer capability of MHPA-FPC.The total thermal resistances lowers to nearly half of the original level when contact material between the condenser of MHPA and the heat exchanger changes from conductive silicone to conductive grease.These results could provide useful information for the optimal design and operation of MHPA-FPC.