Optimal Structure Design of a Thermosyphon Solar Water Heating System with Thermal and Dynamic Models

Based on heat balance and momentum balance among different components, dynamic models to predict the thermal performance of a domestic thermosyphon solar water heating system (TSWHS) were established. To validate these models, an outdoor experimental platform was built and tests were conducted on three typical summer days in Zhuhai city, China. Results indicate that the temperature rise of water in a tank predicted by these models agrees very well with experimental data. Therefore, these models were verified. Then, these models were used to investigate the effect of design parameters on the thermal performance of a TSWHS. For the TSWHS, results indicate that its air gap thickness prefers to be set at 25 mm because the heat loss through its glass cover stops decreasing above this value; both the energy loss and the final temperature of water in the tank decrease with increasing water tank volume. Therefore, considering the balance between photo-thermal efficiency and water temperature requirement, the tank volume can be determined among 130–150 L in this work. Because the improvement of energy gain from an optimal installation slope of the TSWHS cannot compensate for the operation and maintenance costs, the installation slope can be fixed at a value which is equal to the local latitude.     

太阳能热水系统的实验研究

性能良好的太阳能集热器是太阳能热水系统关键设备之一。该文简单介绍了强制循环太阳能热水系统原理 ,着重考察了一种低温平板太阳能集热器在青岛气候条件下的工作性能 ,测定了瞬时效率曲线 ,其热损系数为 5 .76W /(m2 ·℃ )。     

Solar Water Heating

This paper summarises one of the four final report titles published under CEC contract NO ES-A-P-009-UK(N), “Performance Monitoring of Solar Heating Systems in Dwellings (Part II)”.

The report described here contains measured monthly performance data from monitored solar water heating projects located in member countries of the European Community. Reported performance figures range from 400 to 1,200 MJm^? 2 p.a. (100 to 300 kWh/m² p.a.), which represents 10 to 30% of global radiation incident on the collectors. It is suggested that an annual performance of 1,000 to 1,400 MJm^? 2 p.a. is realistic as a performance target for better optimised systems.     

Natural Convection in a Porous Cavity with Sinusoidal Heating on Both Sidewalls

A numerical study has been performed on buoyancy-induced convection in a square porous cavity. The vertical sidewalls of the cavity are maintained with sinusoidal temperature distribution. The finite volume method is used to numerically solve the nondimensional governing equations. The Brinkman Forchheimer extended Darcy model is used in the present study. The results are analyzed over a range of the amplitude ratio, phase deviation, porosity, and Grashof and Darcy numbers. It is found that the heat transfer rate is increased when increasing the amplitude ratio, porosity, and Darcy number. The nonuniform heating on both sidewalls provides higher heat transfer rate than the nonuniform heating of one wall.     

自然循环太阳能热水系统热虹吸压力的计算、分析及讨论

描述了常用平板型太阳能热水系统的结构特点,设计方法,计算,分析和讨论了自然循环太阳能热水系统在不同运行条件下的热虹吸压力及系统运行效率。     

内插式真空管太阳能热水器热特性理论及实验研究

设计了一种内插式真空管热水集热器,通过对其能量转换、传输特性研究,建立了内插式真空管集热器的热特性分析模型,并对不同设计参数和气候条件对内插式真空管热特性的影响进行了分析。结果表明,设计的集热器理论热效率最大可达79.5%,但其受环境温度、集热器工作温度等影响较大。此外,设计了由14只内插式真空管组成的太阳能热水器,采用迟滞算法将热水温度控制在50～55℃,实验结果表明,样机系统的日热效率可达55.0%,样机输出热水近120 kg,具有较好的实用价值。     

多功能太阳能采暖集热器研究

本研究设计了一种可转换冬季与夏季功能的太阳空气集热器,该集热器的集热板为一组叶片,叶片由传动装置联接在一起,吸热板叶片可以转动,并且能够跟踪太阳能运行,最大限度吸收太阳辐射。吸热板背面涂以热反射涂层,夏季叶片翻转180,°反射红外辐射隔热降温。文章分析了影响太阳空气集热器的瞬时集热效率的各种因素,并对其热性能进行了试验。     

Natural Convection in a Horizontal Cylinder with Partial Heating: Energy Efficiency Analysis

The current study reports a numerical analysis of free convection of air in an isothermal horizontal cylinder, cooled and heated at different wall locations. Three heater sizes are discussed in this study. The first heated zone is spread across one-quarter of the sidewall; the second is uniformly distributed over the half of the wall and the third active wall covers three-quarters of the cylinder. Five various locations are considered and examined for each active zone of the sidewall. The comput...     

直流-自然循环复合式太阳能热水系统

分析了目前常用的各类太阳能热水系统的特点，提出了一种直流－自然循环复合式太阳能热水系统的结构，并分析了该系统的特性，认为这种系统具有广阔的应用前景。     

太阳能热水系统的节能效益分析

以呼和浩特北方宾馆为例，计算分析了该系统相关的节能效益指标，并列出了其他一些工程实例的节能效益指标，初步分析研究了太阳能热水工程的节能效益。给出了太阳能热水系统的增投资的回收期算法。     

浅谈太阳能热水系统辅助加热方式的选择

介绍了全寿命周期成本分析的含义及重要性,分析了目前太阳能辅助加热方式的种类及特点,并从工程实例出发分析了不同加热方式的全寿命周期成本.指出了在节能环保、自主可靠、经济适用的前提下,空气源热泵辅助加热系统的优势.     

广州鼓励民用建筑推广太阳能热水

广州市政府办公厅下发《广州市民用建筑节能管理试行办法》（以下简称《办法》），《办法》将从2011年3月1日起正式施行。该办法指出将从规划源头控制高耗能建筑的建设，其中包括12层以下新建居住建筑应采用太阳能热水系统。《办法》所称的民用建筑，     

太阳能生活热水系统应用研究

介绍了太阳能热水系统的基本形式,以及其相应的太阳能热水器、集热板的优缺点.并阐述了太阳能建筑一体化技术应用也是实现建筑节能与住宅建筑可持续发展的亮点.     

菲涅尔太阳能集热器驱动的冷热电联供系统热力性能分析

为了提高冷热电联供系统的灵活性和热力学性能,将线性菲涅尔集热器、吸收式热泵、有机朗肯循环、地源热泵相结合,提出了一种基于线性菲涅尔太阳能集热器的新型冷热电联供系统。在EES软件中建立了提议系统和参考系统的热力学模型,将提议冷热电联供系统和参考系统的性能进行比较,并分析了一些关键参数对系统性能的影响。结果表明：该系统在设计工况下,一次能源利用率可达到78.04%,太阳能发电效率为8.2%,热电比为10.13;与参考系统相比,节约了一次能源11.8%,提高了系统满足用户负荷的灵活性;夏季辐照强度每增加100 W/m²,一次能源利用率约增加0.95%,太阳能发电效率增加2.73%;在热分配比为0.2时,系统一次能源利用率最大为80.5%;热电比随着辐照强度和热分配比的增大而减小,当热分配比增大0.4时,夏季系统热电比下降了86.2%,冬季热电比下降了84.9%。     

整体式太阳能空气集热器传热性能分析

研究了整体式太阳能空气集热器的传热性能,建立了稳态假设下的热量传递物理数学模型;通过CFD软件计算,分析了进口空气流速、空气温度、太阳辐照强度对集热器传热性能的影响;计算结果表明:集热器的集热效率随工质流速的增大而增大、随进口温度的升高而下降、随太阳辐照度的波动很小,受太阳辐射强度的影响不大。     

整体式太阳能空气集热器热性能研究

对一种新型的整体式太阳能空气集热器,根据简化的物理模型利用CFD软件对集热器内部的流场、压力场和温度场进行数值模拟分析,并与传统拼装式集热器阵列进行对比。结果表明,传统拼装式集热器阵列内部存在流动的滞留区,内部温度分布不均匀,吸热板有局部的高温区域;整体式空气集热器内部流场、压力场和温度场分布比较均匀,有明显的温度梯度,吸热板与空气能够更好的进行对流换热。因此,整体式空气集热器的热性能优于传统拼装式空气集热器阵列。     

Numerical Analysis of Thermal and Dynamic Behavior of a Roof Solar Collector

In some regions with a specific climate, summer comfort in the rooms located below the roof becomes critical if the roof system is not well designed. In order to analyze the efficiency of this system a numerical model was developed. This model is based on the study of the natural convection coupled with radiative heat transfer in an inclined air channel. The configuration studied is an inclined channel formed by two parallel plates. The upper and lower plates were maintained at fixed temperatures. The air flow in the channel which is due to the buoyancy forces is fully turbulent and the turbulence was modeled by using the k‐ε model. Some numerical results obtained were validated using the experimental works of Khedari and colleagues and those of Nouanégué and colleagues. The effect of physical and geometrical parameters and the radiative heat transfer on the channel behavior is shown. Correlations for Nusselt numbers and air flow rate were obtained as functions of the geometric parameters and the Rayleigh number. These correlations can be used in other models that represent this system.     

Natural Convection in a Micropolar Fluid with Thermal Dispersion and Internal Heat Generation

A similarity solution is presented for the flow of a micropolar fluid along an isothermal vertical plate with an exponentially decaying heat generation term and thermal dispersion. Numerical solutions are obtained for the governing equations. Results for velocity, angular and thermal functions are displayed for a range of values of the material parameters of micropolar fluid and thermal dispersion parameters.The data for friction factor, Nusselt number and wall couple stress have been tabulated for a range of thermal dispersion parameters s, Prandtl numbers Pr and micropolar parameter.     

双水箱太阳能热水系统的水位关系研究

为了解决工程中常因双水箱太阳能热水系统的设计不当造成的水箱溢水等问题,论文基于强制循环式双水箱太阳能热水系统,通过分析研究系统运行中双水箱的水位变化,给出了两水箱间可能出现的最大水位差与连通管管径之间的函数关系。同时,对应用示例的计算与分析,给出了相应的预留空间大小、连接管管径以及各相关管口的高度位置。本研究对于工程上设计确定双水箱预留空间大小、连通管管径、各相关管口的高度位置具有理论指导意义。