分布式能源冷热供应系统模拟研究

采用TRNSYS软件进行系统模拟,介绍太阳能联合分布式能源系统的运行原理和过程。通过系统流程图,建立了太阳能集热器、余热锅炉和换热器的物理模型,同时建立了太阳能集热器和余热锅炉的数学模型。从装置选型、设置参数等方面,模拟出太阳能集热器在全年和1月份的出口温度,分析集热器的出水温度能否达到实际要求,并对余热锅炉和换热器的出口温度进行了对比,分析输出蒸汽温度及水温是否满足用户热负荷需求。     

平板型集热器驱动的小型太阳能吸收式制冷系统运行分析与优化研究

文章以平板型集热器作为驱动热源,构建了一套额定制冷功率为17.6 kW的小型太阳能吸收式制冷系统,并基于TRNSYS软件构建了小型太阳能吸收式制冷系统模型,研究了太阳辐射强度、集热器面积和蓄热水箱体积的变化对系统运行性能和制冷功率的影响。模拟结果表明:在系统运行过程中,平板型集热器的工作温度约为90℃,单效吸收式制冷机的驱动温度为72.5～95℃,单效吸收式制冷机的最大制冷效率可以达到0.85,由此可知,当热源温度与驱动温度的匹配度较好时,既能保证单效吸收式制冷机的高效运行,又能减少能源品位的浪费;白天,当小型太阳能吸收式制冷系统运行时,系统的太阳能保证率为57.5%,一次能源节约系数可达到0.25,此时,小型太阳能吸收式制冷系统的制冷性能优于电压缩制冷系统。     

太阳能集热器热性能测试系统

为满足工业生产及科学研究中对太阳能集热器测试的需要,按照GB/T 4271-2007《太阳能集热器热性能试验方法》设计了太阳能集热器热性能测试系统。系统由恒温控制台、恒温水箱、旋转平台、循环水泵和连接管路等组成,可对采用液体作为传热工质的集热器进行稳态和动态测试。选取了温度、流量、压力、风速及太阳辐照度传感器,设计了其硬件通讯电路,利用Labwindows/CVI软件为基础开发了测试系统的软件部分,实现了数据的采集、分析和显示。测试结果表明,系统能准确完成集热器的瞬时效率、时间常数、入射角修正系数及两端压力降等的测量,可为准确掌握集热器热性能提供试验平台。     

蓄热水箱温度分层模型与分析

利用多节点模型描述蓄热水箱温度分层,将这种模型应用到太阳能生活供热系统中,研究温度分层对太阳能供热系统性能的影响。研究表明:水箱温度分层显著提高集热器效率,对平板集热器的影响大于真空管集热器。用水模式、供水温度、供回水温差,对水箱温度分层都有影响。     

无盖板渗透型太阳能空气集热器热性能的实验研究

无盖板渗透型太阳能空气集热器是一种易于实现建筑一体化的高效新风预热及干燥装置。为了掌握无盖板渗透型集热器在实际工况下的热性能,建造了集热面积为2.2 m2的太阳能空气加热系统实验台,并在2009年2月至2009年4月对其热性能进行了户外瞬态实验研究。实验结果表明出口空气温度随辐射强度的增加而升高,太阳辐射强度是影响集热器出口空气温度的最重要因素,而室外空气温度的影响极小。空气温升随风量的增加而减小,集热器热效率随风量的增加而增大。在三个测试日中集热器的平均热效率分别为58%、63%和72%,高于普通平板太阳能空气集热器。     

太阳能地板辐射系统用于夜间采暖时系统性能的实验研究

利用太阳能集热器制得低温热水作为地板辐射采暖系统的热源,是一种清洁、节能、舒适的采暖方式。在南京地区搭建了太阳能地板辐射采暖系统实验台,系统运行策略为白天集热、夜晚采暖,通过实验得到了集热器集热效率、地板进出水温度、室内不同朝向围护结构温度、不同高度的空气温度等参数,最后对系统的性能进行了概括和总结。     

以太阳模拟器为光源的集热器室内稳态性能对比

以大面积太阳模拟器考察了平板式太阳能集热器、热管真空管式太阳能集热器、全玻璃真空管式太阳能集热器室内稳态下的性能。经测定,全玻璃真空管式太阳能集热器的时间常数为1235 s,其压力曲线随流速变化平缓。在辐照强度为900 W/m2、进口温度低于57℃时,平板太阳能集热器的效率高于热管真空管式和全玻璃真空管式太阳能集热器;进口温度高于57℃时,式真空管式太阳能集热器的效率高于平板式太阳能集热器;进口温度高于64℃时,全玻璃真空管式太阳能集热器的效率高于平板式太阳能集热器。在工作温度范围内,全玻璃真空管式太阳能集热器的效率低于热管真空管式太阳能集热器。设计、流动和换热特征影响了集热器的性能。     

改进型微热管平板太阳能空气集热器性能分析

近年来,以空气作为换热介质的太阳能集热器越来越受到重视。本文以微热管阵列为核心传热元件,设计并搭建了改进型微热管平板太阳能空气集热器性能测试系统。通过实验研究了不同空气流量和不同进口温度对集热器集热性能的影响,获得相应参量对集热器的出口空气温度、集热效率和微热管阵列蒸发段温度的影响特性,分析对比了改进前后集热器的集热性能,得到了集热器效率的归一化曲线。实验结果表明,改进型微热管平板太阳能空气集热器在夏季240 m³/h空气流量时集热性能最佳,改进后的集热器相比原集热器在夏季的平均集热效率最高同比提升13.8%;在240 m³/h风量下的平均集热效率最高达到了74%,对应集热器的压降为9.2 Pa。     

直膨式太阳能热泵系统的模型仿真

考虑了集热器中制冷剂压降的存在,利用平衡均相理论建立了太阳能集热/蒸发器的两相流模型,同时建立了压缩机、冷凝器的数学模型.从理论上分析了集热器中制冷剂的压降、集热器的类型、集热面积、太阳能辐照度、环境温度、压缩机容积以及冷凝温度等因素对直膨式太阳能热泵系统热工性能的影响,并在此基础上给出了改善系统性能的建议.     

基于太阳能热发电系统效率的最佳运行温度

分别对汽轮机组热机效率和太阳能集热器效率进行了分析,并对热机效率进行了修正,得到了不同状况下的太阳能热发电系统效率和最优运行温度。研究表明:随着太阳辐照度、太阳能热发电系统聚光比的增加,系统效率提高,最佳集热温度升高;然而,当综合传热系数增大时,系统效率下降,最佳集热温度降低;太阳能集热器光学效率的变化,只影响系统效率,对系统的最佳集热温度影响不大。     

基于太阳能集热-蓄热技术发展的吸收式制冷、供暖、供热水联供运行系统

基于太阳能集热器和热能蓄热器这一套能量转换和收集设备的基础上,为吸收式制冷、供暖、供热水提供热力驱动。系统组成包括太阳能集热蓄热部分,共用集热蓄热装置的制冷、供暖、供热水等三大功能循环系统,电路及其自动控制部分。该系统通过集热管和蓄热装置,将分散化、低品位的太阳能转换为较高品位的热能并存储起来,同时将其它形式的废热通过换热装置储存于蓄热装置内。三大循环能够按需获取热能,提高能源的利用效率。     

Experimental investigation of a domestic solar water heater with solar collector coupled phase-change energy storage

Phase change materials (PCMs) have good properties such as high thermal capacity and constant phase change temperature. Their potential use in solar energy storage is promising. Tests of exposure and constant flow rate are performed to investigate the thermal performance of a domestic solar water heater with solar collector coupled phase-change energy storage (DSWHSCPHES). Due to the low thermal conductivity and high viscosity of PCM, heat transfer in the PCM module is repressed. The thermal performance of the DSWHSCPHES under exposure is inferior to that of traditional water-in-glass evacuated tube solar water heaters (TWGETSWH) with an identical collector area. DSWHSCPHES also performs more efficiently with a constant flow rate than under the condition of exposure. Radiation and initial water temperature have impacts on system performance; with the increase of proportion of diffuse to global radiation and/or initial water temperature, system performance deteriorates and vice versa.     

Wind effect on the performance of a solar organic Rankine cycle

The effects of wind, ambient temperature and solar radiation on the simultaneous productions of mechanical work and heat by a solar Rankine cycle are studied. The on site experimental study uses the pentafluorobutane R365mfc as working fluid in a system consisting of a small-scale single glazed flat plate collector, a micro turbine, a condenser and a pump. The theoretical study focuses on the prediction of the optimum operating temperature of the collector according to the solar radiation, the temperature of air and the wind speed. Then, the total production of mechanical and thermal energy is calculated during a sunny day for which various wind speeds are simulated. The results highlight the effect of wind on the corresponding production and they also establish the value of the recommended evaporating temperature according to weather conditions.     

太阳能季节性地下水池蓄热供热系统的模拟研究

分析了太阳能季节性地下水池蓄热供热系统的运行原理,建立了蓄热水池的数学模型,以哈尔滨一栋采用该供热模式的别墅建筑为实例,以满足太阳能保证率为目标、地下水池中水温为约束,通过改变集热器面积和地下水池的体积及其他相关参数,模拟计算得到太阳集热器面积和地下水池半径的最佳匹配、系统集热量与热损失量和水温与集热效率的关系.     

Experimental study of the performance of a solar thermal-photovoltaic integrated system

In this work a self-contained solar heating forced water cooling unit was selected and assembled. It consists of three flat-plate solar collectors, each of area 1.2 m², a.d.c. pump, a photovoltaic module and a storage tank. The electrical power produced by the photovoltaic module operates the d.c. pump, which circulates the cooling water through the solar collectors to transfer the heat to the storage tank. The electrical voltage and current, the water rate of flow, and water temperature at inlet and outlet of the collector were all measured. Solar irradiation, wind speed and ambient temperature were also measured. Daily distribution of electrical current, water mass rate of flow, module efficiency and collector efficiency were plotted in figures. Module efficiency, pump efficiency and collector efficiency were taken as dependent variables, while the solar irradiation, ambient temperature and time were the independent variables. Optimum values were graphically indicated and related to each other in a clear discussion. An economic study and comparison of three different systems were carried out: a common thermosyphon system; an a.c. pump circulating system; and this system, which is a d.c. pump circulating system. Results revealed that collector efficiency reached a daily average value of 47% due to d.c. pump installation powered by photovoltaic electric output.     

太阳能-土壤源热泵联合供暖系统优化研究

针对严寒地区的气候条件,选取哈尔滨地区某居民住宅小区作为研究对象,利用TRNSYS软件对太阳能-土壤源热泵联合供暖系统(SGCHP)进行计算分析。结果表明:太阳能-土壤源热泵联合供暖系统中太阳能集热器对热泵机组的进水温度和COP以及节电量等方面有改善作用;对太阳能-土壤源热泵联合供暖系统中太阳能集热器面积与地埋管管长的最佳配比的优化结果表明,1 m~2太阳能集热器可保证17～27 m长的地埋管取热平衡。并继续模拟了沈阳地区,并以哈尔滨地区为基准,给出严寒地区该参数的推荐值。     

An analysis of solar heating systems that use vapor-compression cycles

This paper analyzes the technical and economic performance of solar heating systems that use vapor-compression cycles, circulating a compressible fluid as the working fluid. With conventional solar heating systems that use water or as their working fluid, the collector inlet temperature is equal to that of the storage outlet temperature. Operating the system on a cold day can result in large thermal losses to the surroundings and, thus, low useful heat gains. A vapor-compression cycle may be attractive because it allows the collector inlet temperature to be lowered so that the heat gain of the collector can be increased. Such a system is simulated and a preliminary economic analysis performed. The results indicate that the vapor-compression system can collect almost 50% more solar energy than a conventional system if the collector area of the two systems are the same.     

大型太阳能烟囱发电站热力分析与计算

利用热力学方法建立太阳能烟囱发电系统中集热棚、烟囱及风力透平的热气流能量转换过程的理论模型及求解方法.鉴于太阳能烟囱发电站的大尺寸特征,采用一维假设建立热气流传热模型,使用龙格-库塔方法对非线性能量方程进行数值求解.对集热棚直径3 600 m,烟囱高950 m,设计功率100 MW的大型太阳能烟囱发电站进行分析与计算,给出了该电站的风力透平轴功率随质量流量和太阳辐射强度变化的规律,为风力透平机组提供热力气动设计参数,为大规模开发利用太阳能提供借鉴.     

Experimental investigation on thermal performance of thermosyphon flat-plate solar water heater with a mantle heat exchanger

The thermal performance of thermosyphon flat-plate solar water heater with a mantle heat exchanger was investigated to show its applicability in China. The effect on the performance of the collector of using a heat exchanger between the collector and the tank was analyzed. A “heat exchanger penalty factor” for the system was determined and energy balance equation in the system was presented. Outdoor tests of thermal performance of the thermosyphon flat-plate solar water heater with a mantle heat exchanger were taken in Kunming, China. Experimental results show that mean daily efficiency of the thermosyphon flat plate solar water heater with a mantle heat exchanger with 10 mm gap can reach up to 50%, which is lower than that of a thermosyphon flat-plate solar water heater without heat exchanger, but higher than that of a all-glass evacuated tubular solar water heater.     

On the Development of the Solar Photovoltaic and Thermal (PVT) Collector

The solar photovoltaic and thermal (PVT) collector is a device which converts solar energy into thermal and electrical energies simultaneously. The PVT collector can be used whenever both electricity and hot water are required, for example, for domestic uses. It is a known fact that the efficiency of the solar (photovoltaic) cells decreases as operating temperatures increase. Therefore, a better and a more efficient use of these cells, calls for cooling the cells. One method for doing that is to use a heat exchange system, which cools the cells by means of a heat absorbing medium, such as water, flowing in pipes. The heat removed from the cells results in hot water. Another advantage of the PVT collector is its higher overall efficiency per unit area and lower packaging costs due to its compact design. In this paper a theoretical analysis of the PVT collector using a simulation model is presented. In this model the PVT collector is divided into a matrix of ``small' PVT collector units, each one consisting of several layers. The energy balance of each ``small' PVT collector unit is studied by analysis of the energies entering and leaving each one of its layers. Later, the process is applied to the PVT collector itself. A PVT collector was designed and constructed and putthru a series of experiments under varying load conditions, insolation levels and other climatological conditions.