太阳能空气集热器热性能测试方法研究

在参考国内外标准和文献资料的基础上,建立太阳能空气集热器的测试数学模型,给出太阳能空气集热器热性能测试的试验方法,在国家太阳能热水器质量监督检验中心(北京)的实验室进行太阳能空气集热器实际测试,并对测试结果进行分析.给出适合我国太阳能空气集热器质量水平的太阳能空气集热器热性能测试方法,为制定我国太阳能空气集热器热性能测试国家标准做技术和实验储备.     

太阳集热器热性能测试方法研究进展

以集热器热性能的测试和评价方法为研究对象,综述了太阳集热器热性能测试方法的发展现状,并对已有的具有代表性的集热器热性能测试方法做了较详细的分析,指出了各测试方法在测试过程和参数估计过程中所具有的优缺点,并在此基础上提出当前集热器热性能测试存在的问题和今后的研究重点.     

平板集热器热性能的试验研究

本文简述了研究平板集热器性能测试的意义,介绍了集热器的性能测试方法和性能方程。 文章还报道了我校自建的性能试验台的概况,以及用这座试验台对一种管板式太阳能热水器进行试验研究的结果。最后,就平板集热器性能测试中的若干问题进行了深讨,提出了建议。     

三角腔体菲涅尔线集热器性能实验研究

介绍了一种线性菲涅尔集热器,并进行了性能测试实验。集热器采用三角形腔体管束型吸收器,镜场采用超白玻璃反射镜,安装时做微弧处理,跟踪方式为单排独立驱动跟踪。参考GB/T4271-2000和ASHRAE 93-86两种标准,采用瞬时法对集热器进行性能测试,衡量集热器的工作性能。根据实验测点数据,计算出菲涅尔线聚焦集热器的空晒系数、热损系数以及集热器效率。实验结果表明,工作温度为150℃时,集热器效率可以达到36.6%,热损系数为110W/m.     

平板型太阳集热器热性能的快速测试方法研究

对快速测量平板太阳集热器热性能的瞬态测试方法进行研究，并将快速测试方法的测试结果与国标GB／T4271-2000(平板型太阳集热器热性能试验方法)规定的测试方法所得的结果进行比较。通过对比可见，基于瞬态测试的快速测试方法可以得到与稳态测试同样的结果，考虑到现有太阳辐射表的精度，只要太阳辐照度大于300W／m2瞬态测试即可有效，且对测试期间太阳辐照度的变化无要求。在除雨雪天的情况下，整个测试可以在1d内完成。     

典型太阳能集热器热性能研究

以当今市场保有量最高的两种典型太阳能集热器——全玻璃真空管型太阳能集热器和平板型太阳能集热器为研究对象,从能量传递角度,构建了太阳能集热器在理想状态下的热效率模型,并依据模型计算了极限热效率;最后对两种太阳能集热器做了热性能测试实验,并使用最小二乘法拟合出太阳能集热器瞬时热效率与归一化温差的关系,对比两种太阳能集热器在同一实验条件下的极限热效率和热损失系数,并验证了该模型的正确性。     

遮阳板式太阳能相变集热器的实验研究

研制了遮阳板与集热器一体化的新型太阳能相变集热器,通过搭建的实验测试平台对其集热性能及隔热特性进行了实验测试。该建筑构件具备遮阳隔热及太阳能集热功能,为在建筑中高效利用太阳能,实现太阳能与建筑一体化提供一种新的工程应用模式。通过实验测试,对该集热器在不同工况下的集热性能、隔热特性及其影响因素进行了系统分析研究,提出了该集热器的累积集热量、集热效率、隔热特性等性能评价指标。测试结果表明,遮阳板式太阳能相变集热器的平均集热效率可达12.3%,隔热效果优于普通遮阳板。     

渗透型太阳能空气集热器集热效率研究

将CFD模拟引入太阳能空气集热器设计研究领域,对渗透型太阳能空气集热器(UTC)的工作特性进行了模拟分析,并与传统空气集热器进行了比较.在数值模拟的基础上,制作了几种实验模型并进行了实验研究,对其送风温度和热效率进行了测试.通过模拟和模型实验,说明了UFC在新风预热领域中无可比拟的优势,显示了CFD工具在空气集热器研究领域中的优势.     

铝幕墙板太阳能集热器的性能研究

研制了一种铝幕墙板与集热元件一体化的新型太阳能集热器,并通过所搭建的测试平台对其集热性能及隔热特性进行了测试研究。通过实验测试,对该集热器在不同工况下的集热性能、隔热特性及其影响因素进行了系统分析,得出了集热器的累积集热量、集热效率、隔热特性等性能评价参数。测试结果表明,铝幕墙板太阳能集热器的平均集热效率为23%,隔热性能优于普通铝幕墙板。该装置具有太阳能集热及隔热功能,为建筑高效利用太阳能,实现太阳能与建筑一体化提供了一种新的工程应用模式。     

太阳能集热器动态测试方法简介

本文介绍了目前国际上影响较大的几种太阳能集热器的动态测试方法的原理、实验装置、测试步骤,分析了它们在实验条件要求、实验步骤、应用范围、数据处理方法和精度等方面的差别。     

A new method for the measurement of solar collector time constant

A new test method about the time constant of the solar collector has been presented in this paper. It is simple and has been validated through experiments. With the new method it is not necessary to adjust the inlet temperature of the transfer fluid as closely as possible to the ambient air temperature. Also, it is not necessary to know the characteristic parameters of the collector in advance. The model used in the paper is a first order system model, as in most cases. The experimental data obtained from the test of solar collector time constant shows that the solar collector is not a strictly first order system. A criterion is proposed to decide whether the system is a first order system or not and the resemblance of the system to the first order system.     

Short term experimental procedure for the determination of solar collectors' time constant

The thermal behaviour of solar collector during transient heat process imposed by step in solar irradiance intensity has been analysed. A new simple method to obtain the time constant value from short time experiment is described. The influence of high working temperatures on solar collector time constant is also studied.     

Solar Collector Parameter Identification by Step Input Test Procedure

A fast test procedure is introduced for identification of solar collector parameters. The tests were accomplished by exposing the collector to the sun and then shielding it from the sun, with the flow rate and inlet temperature held constant. The transient heat up and cool down data points were used to identify the collector parameters specified for the first order and second order models. The experimental results of the collector performance by the step input test procedure were found in fairly good agreement with those of standard steady-state procedure.     

NUMERICAL SOLUTION AND VALIDATION OF A DYNAMIC MODEL OF SOLAR COLLECTORS WORKING WITH VARYING FLUID FLOW RATE

A method to calculate the short-term dynamic behavior of solar collectors, working with varying fluid-flow rate, has been developed. It is based on a system of first-order partial differential equations. The method was applied to model a large unglazed collector used for heating a public outdoor swimming-pool in Marburg (Germany). A validation with data measured at this collector showed good short- and long-term accuracy of the model at constant and varying flow rates. Furthermore, the dynamic behavior of the detailed model was compared to that of several model approximations especially at varying flow rate. In the case of unglazed collectors a simple dynamic model, based on an ordinary differential equation, gives accurate results in most practical applications even at varying flow rate. The extension of the method to flat-plate collectors is demonstrated as well.     

Direct measurement and analysis of thermosiphon flow

The thermosiphon flow rate has been measured directly by adapting a simple and well-known laboratory technique, a constant level device, to a solar collector operating in the thermosiphon mode. The measurements were performed as a function of thermosiphon head and inlet temperature. The thermosiphon flow rate data were correlated both with the temperature change across the solar collector (ΔT) and the global insolation rate. The minimum ΔT threshold value, necessary to initiate thermosiphon flow in the morning was determined as a function of thermosiphon head and the corresponding thermosiphon pressure heads were observed to be invariable. The thermosiphon flow data were utilized to construct a standard efficiency test curve, thus showing that this technique can be applied for testing collectors in the thermosiphon mode. The instantaneous collector efficiency was also determined as a function of time of day.     

A new look at long term collector performance and utilizability

A simple technique has been developed to calculate monthly collection efficiency or monthly utilizability for solar thermal flat-plate collectors. It is applicable to south facing tilted collectors operating with a fixed fluid inlet temperature although extensions to other more generalized uses of utilizability are discussed. The heart of the technique is an empirically determined performance map that makes possible quick evaluations of changes in collector design, geographic location and collector inlet temperature. The collector input variables are those that are commonly measured in most thermal test procedures; geographic input variables are the mean monthly temperature and K_T (the Liu and Jordan clearness factor). The procedure was developed for monthly optimum fixed tilts but a simple correction can be made to incorporate arbitrary monthly fixed tilts. The method, in general, gives good results compared to long term hourly simulation. The technique also allows one to determine under what operating conditions collector performance begins to depend on site-to-site solar radiation/weather variability and what uncertainties can be expected from its use.     

Field performance and operation of a flat-glass solar heat collector

A “Base-Line,” flat-glass solar heat collector has been designed and constructed that can be manufactured economically for commercial use. Four of the collectors, 34 by 76 in. (approximately 18 ft²), were installed to provide hot water to a private home in Melbourne, Florida.The details of the collector are described, including coverplates, solar absorber, absorber coating, spacers, seals and glazing.A simple relationship has been established between the collector efficiency, the collector temperature and the rate of insolation for constant rates of flow of circulating fluids.The theoretical and field performance curves have been correlated for collector efficiency, collector temperatures, incident solar radiation and ambient air temperatures. The effect of fluid flow on collector temperatures for various collector parameters has also been presented.     

The effects of air leaks on solar air collector behaviour

The construction of conventinal solar air collectors and the fact that they will operate with a significant pressure difference between the heated air stream and ambient, suggests that significant quantities of air may leak into or out of them. A search of the literature reveals no consideration of the effects these air leaks may have on the validity of collector efficiency measurements, on the efficiency itself, or indeed what the meaning of efficiency is under such operating conditions. This paper discusses the meaning of collector efficiency when leaks into the collector occur, analyses the effects on efficiency measurements, and solves the collector efficiency for the simple case of a constant leakage rate along the collector. Assuming that air leaking in from ambient can replace deliberate fresh air supply to the load as in building heating, then significant measurement errors are made if air leaks in to the collector are not accounted for. Further, the collector efficiency is increased over the no leak case, so that complex construction methods to make the collector air tight are probably not warranted.     

槽式太阳能集热器热性能实验测试

针对天津市槽式太阳能集热系统性能测试平台,对不同太阳辐射强度、入口流体温度以及不同工质流量状况下集热效率和集热管压降变化规律进行实验测试,通过测试数据对槽式太阳能集热器热性能进行分析.试验结果表明:在天津地区槽式太阳能集热器集热效率可以达到66.1％;太阳辐射强度的增强,会提高集热效率,并且集热器进出口的压降会随之降低...     

太阳集热器时间常数分析及测试讨论

时间常数作为集热器最重要的动态特性之一，表明了集热器对太阳辐照瞬变响应的快慢，时间常数的测试是集热器热性能测试的重要内容。本文在一阶系统基础上讨论了时间常数，提出了在集热器时间常数测量基础上，判定集热器与一阶系统的符合程度的方法。同时提出了当集热器很好的符合一阶系统时更准确得出时间常数的方法。