Thermodynamic Analysis and Optimization of Flat Plate Solar Collector Using TiO_(2)/Water Nanofluid

To research solar energy's efficiency and environmental benefits,the thermal efficiency,exergy,and entropy of solar collectors were calculated.The experiment involved two glass-topped collectors,fluid transfer tubes,and aluminum heat-absorbing plates.Glass wool insulation minimized heat loss.A 0.5% TiO_(2)/Water nanofluid was created using a mechanical and ultrasonic stirrer.Results showed that solar radiation increased thermal efficiency until midday,reaching 48.48% for water and 51.23% for the nanofluid.With increasing mass flow rates from 0.0045 kg/s to 0.02 kg/s,thermal efficiency improved from 16.26% to 47.37% for water and from 20.65% to 48.76% for the nanofluid.Filtered water provided 380 W and 395 W of energy in March and April,while the nanofluid increased it to 395 W and 415 W during these months.Mass flow generated energy,and the Reynolds number raised entropy.The noon exergy efficiency for nanofluids was 50%-55%,compared to 30% for water.At noon,the broken exergy measured 877.53 W for the nanofluid and 880.12 W for water.In Kirkuk,Iraq,the 0.5% TiO_(2)/Water nanofluid outperformed water in solar collectors.

Experimental Study of Temperature and Humidity Variations in an Incubator Fitted with a Flat-Plate Collector

In Burkina Faso, where livestock farming is widely practiced, particularly in rural areas without access to electricity, solar energy offers a viable alternative due to the country’s abundant sunshine. To support poultry farmers in increasing their production, we developed a solar-powered incubator equipped with a flat-plate collector, requiring no grid electricity. This is a new approach that we want to experiment with because the incubators on the global market operate either with the electricity grid, photovoltaic, gas or oil and not a solar thermal concentrator. This solar concentrator represents the heat source of the device during the day. We plan to look for rocks with high thermal inertia in order to heat them during the day using another flat solar concentrator and then introduce them into the incubator at night to continue the incubation process. In 2022, we conducted a simulation to study temperature variation inside the incubator. In this work, we built a prototype to experimentally evaluate key hydrothermal properties such as air temperature and humidity. Furthermore, we will not introduce rocks into the incubator overnight but will let the system run overnight to see how the hygrothermal properties vary. The findings revealed temperature fluctuations from 25˚C to 65˚C, instead of the desired 36˚C to 38˚C, and humidity levels ranging from 15% to 57%, instead of the target 55% to 75%. Solutions have been proposed to enhance the system’s performance.

Studies on solar flat plate collector evaporation systems for tannery effluent(soak liquor)

Heat and mass transfer analysis of an incompressible, laminar boundary layer over solar flat plate collector evapora- tion systems for tannery effluent (soak liquor) is investigated. The governing equations are solved for various liquid to air velocity ratios. Profiles of velocity, temperature and concentration as well as their gradients are presented. The heat transfer and mass transfer coefficients thus obtained are used to evaluate mass of water evaporated for an inclined fibre-reinforced plastic (FRP) solar flat plate collector (FPC) with and without cover. Comparison of these results with the experimental performance shows encouraging trend of good agreement between them.

Thermal Loss Analysis of a Flat Plate Solar Collector Using Numerical Simulation

In this paper,we studied theoretically and numerically heated losses of a flat solar collector to model the solar water heating system for the Kazakhstan climate condition.For different climatic zones with a growing cost for energy or lack of central heating systems,promising is to find ways to improve the energy efficiency of the solar system.The mathematical model(based on ordinary differential equation)simulated the solar system work process under different conditions.To bridge the modeling and real values results,we studied the important physical parameters such as loss coefficient,Nu,Ra,and Pr values.They impacted the efficiency of flat solar collectors and heat losses of the system.The developed mathematical models,the design and composition of the software and hardware complex,and automated control and monitoring systems allow solar hot water heating systems to increase the energy efficiency of life support systems and heat supply of buildings by reducing energy consumption for heat supply.The simulation result showed that during the daytime,the temperature of water in the collector is 70°C;the storage of heated water since heated water is cooled at night.We defined that a work period of the system can be extended with high efficiency(April-October)for Almaty region.

Numerical Investigation and Optimization of a Flat Plate Solar Collector Operating with Cu/CuO/Al_(2)O_(3)–Water Nanofluids

Nanofluids are a potential alternative to significantly improving the performance of heat transfer applications. In this work, a numerical analysis to examine the eff ect of dispersing copper(Cu), copper oxide(CuO), and aluminum(Al2O3) nanoparticles in pure water on the performance of a flat plate solar collector(FPSC) and a numerical model was proposed. The influence of the nanofluid type on the thermal efficiency was critically investigated and discussed. The eff ect of the mass flow rate on the performance was also analyzed and discussed. Based on correlations of the thermophysical properties of nanofluids, a sensitivity analysis was used to analyze the impact of the nanoparticles on the base fluid. The results indicate that the performance of the FPSC with Cu/water nanofluid was better than that of FPSCs using CuO/water or Al2O3/water nanofluids. When the mass flow rate of the nanofluids was 8.0 L/min, the efficiency of the FPSC was much greater than those at the flow rates of 5.0 L/min and 2.0 L/min. Mean enhancements in thermal efficiency of 4.44%, 4.27%, and 4.21% were observed when 2.0 L/min was applied using Cu/water, Cu O/water, and Al2O3/water nanofluids, respectively. Improvements in thermal efficiency of 2.76%, 2.53%, and 2.47% occurred when 8.0 L/min was applied.

Solar Thermal Systems Performances versus Flat Plate Solar Collectors Connected in Series

This paper shows the modeling of a solar collective heating system in order to predict the system performances. Two systems are proposed: 1) the first, Solar Direct Hot Water, which is composed of flat plate collectors and thermal storage tank, 2) the second, a Solar Indirect Hot Water in which we added an external heat exchanger of constant effectiveness to the first system. The mass flow rate by a collector is fixed to 0.04 Kg·s–1 and the total number of collectors is adjusted to 60. For the first system, the maximum average water temperature within the tank in a typical day in summer and annual performances are calculated by varying the number of collectors connected in series. For the second, this paper shows the detailed analysis of water temperature within the storage and annual performances by varying the mass flow rate on the cold side of the heat exchanger and the number of collectors in series on the hot side. It is shown that the stratification within the storage is strongly influenced by mass flow rate and the connections between collectors. It is also demonstrated that the number of collectors that can be connected in series is limited. The optimization of the mass flow rate on cold side of the heat exchanger is seen to be an important factor for the energy saving.

Developments of solar collectors in China

China has abundant solar energy resource. Solar thermal collectors, particularly all-glass evacuated tubular collectors, have been studied and developed for 30 years, and solar thermal industry has developed rapidly for 15 years. There are various solar thermal systems, with an operation area of around 108 million m2 in 2007. These systems mainly provide domestic hot water, but some other applications are under extensive study and development as well.

Manufacturing and Thermal Performance Test of (Compound) Solar Collector in Damascus City

Solar water collectors that uses for domestic and industrial applications within temperature up to, are classified under two main types: Flat Plate collector (FP), and Evacuated Tube collector (ET). Thermal performance test results showed that each type have different thermal features. Comparison between (FP & ET) collectors showed that they could take advantages of different thermal features of two types when they work in the same climatic conditions and overlap of these thermal features when they work in different operational conditions. They can take advantage of these features through (compound) solar collector. Compound solar water Collector (CO) composed of a part of flat plate collector shape (FP), and a part of evacuated tube collector shape (ET). Booth have equal reference area, and connected together to be as one Solar collector (CO). Water entered first flat part (FP), then evacuated tube part (ET) then to tank or end-use. In this paper, present design and manufacturing as well the thermal performance test of (compound) solar collector, according to Standard Specification of tests, was EN12975:2001. Mechanical test for (CO) collector conducted successfully according to durability, reliability, and safety requirements. In addition, thermal performance was tested in steady state at the climatic conditions of Damascus city, and concluded the thermal performance of (FP & ET) that constitute (CO) collector. The results showed enhancement of thermal performance.

Performance and Optimization of a Small Hybrid Solar-Thermal Collector

A hybrid solar collector was designed to investigate the effects of combining two different solar collector techniques on the overall collector’s effectiveness. While most solar collectors focus only on one solar collection method, the small hybrid system uses a flat plate collector in conjunction with five evacuated tubes to absorb the most energy possible from both direct and diffuse solar radiation. Data was collected over four months while the system operated at different flow rates and with various levels of available insolation from the sun to evaluate the performance of the solar collector. To understand the relative contribution of the flat plate collector and the evacuated tubes, temperature differences across each part of the system were measured. The results indicate the average first law efficiency of the hybrid system is 43.3%, significantly higher than the performance of the flat plate alone. An exergy analysis was performed for this system to assess the performance of the flat plate system by itself. Results of the second law analysis were comparable to the exergetic efficiencies of other experimental collectors, around 4%. Though the efficiencies were in the expected range, they reveal that further improvements to the system are possible.

Flat Panel Solar Thermoelectric System Size Optimisation at Different Vacuum Levels

A systematic experimental investigation to understand the effect of heat loss and the thermoelectric aspect ratio (cross sectional area and length) on a flat plate solar thermoelectric system performance was carried out. The investigation involved a series of experiments on systems with 4 different sizes of thermoelectric generators, and it was tested in 5 different vacuum levels during the steady-state. The detailed experimental investigation provided a substantial amount of data, which revealed that the system performance of both heat and electricity power were improved when the heat lost was minimised. The system’s performance strongly depended on the aspect ratio of the thermoelectric generators. This finding might have a significant impact on the cost of the system by saving the user’s and the manufacturer’s time in examining different TEGs with different aspect ratios in order to get the optimum size optimisation of the hybrid system, as well as reduce the manufacturing cost.

拉萨地区平板太阳能集热系统变流量运行策略及效益分析

针对室外环境参数波动变化以及蓄热系统温度波动特性,提出一种太阳能集热系统变流量运行调控策略,建立最优流量优化模型,回归得到不同工况下最优流量值多项式函数,并与定流量运行策略下的系统运行性能进行对比分析。结果表明:与定流量运行方式相比,采用变流量调控策略时,集热系统净收益显著提升。对于拉萨地区100 m^(2)串并联形式平板太阳能集热系统,采用变流量运行策略时,虽然运行泵耗增加,但集热量增益更大,相比单位集热面积流量为0.02 m^(3)/(h·m^(2))时,集热系统净收益增加了468.7 MJ,提高了6.75%。

平板集热器冬季高流速运行数值模拟研究

针对平板集热器(FPSC)冬季热水收集温度不足等问题提出高流速运行方案,以期提高系统的集热性能以及全年利用率.通过CFD技术数值模拟FPSC系统在不同流速工况下(0.02~0.15 kg/s)各组件温度的变化情况,计算系统的集热效率,结合温度云图对比高流速运行的优势.结果显示,高流速运行能够减少集热损失,具有更佳的集热性能.

高寒地区平板热管式太阳能集热系统热性能研究

基于呼和浩特地区高寒气候条件,搭建两组完全一致的平板热管式太阳能集热系统,通过实验对比分析太阳辐射强度、传热工质流量、集热板表面积尘等因素对集热器瞬时集热效率以及系统热性能的影响。结果表明,在同等外界条件下,集热器的集热效率随着工质流量的增加而增大,集热效率与太阳辐射强度变化趋势相近,随积尘密度的增加,集热板表面积尘导致系统的得热量减少,集热性能下降。

基于TRNSYS的太阳能耦合污水源热泵系统性能分析

以徐州市某地区某污水处理站为研究对象,为响应节能减排,寻求改造方案。为与建筑一体化,在其屋顶布置平板式太阳能集热器,可直接提供热能,或为污水源热泵机组提供低温热工质,提高热泵机组蒸发器进口温度,进而提高制热效率。基于TRNSYS搭建太阳能耦合污水源热泵系统运行模型,研究表明系统能耗为15.3 MW,系统COP值为4.0,性能较为优越。与污水源热泵系统相比,耦合系统运行较为稳定,系统性能得到较大提升,节能效果明显。耦合系统较污水源热泵系统COP值提高10.5%,能耗降低11.1%。耦合系统评价因子为0.983 2,是最优的制热方案,系统保证制热稳定的同时,兼顾其经济节能性、可靠安全性。

太阳能平板集热器件纵横比与板间距优化

为减小平板集热器件边框对吸热板的遮光损失,该文应用几何光学基本原理建立了平板型集热器件平均有效吸热面积系数的数学模型。利用此模型对年均有效面积系数随集热器件纵横比、板间距、倾角、纬度的变化进行了详细分析。结果表明,年均有效面积系数随板间距的增大而减小,纵横比越大越明显;倾角小于15°或大于75°对集热器件平均有效面积系数都是不利的。为便于应用,文中给出了年均有效面积系数不小于0.90的临界板间距。鉴于对流热损失较小的合理板间距为4～6cm,该文拟推荐合理纵横比≤2/1,北纬20°、30°、40°、50°使用的平板集热器件最大板间距分别约为5.8、5.4、4.7、4.2cm,相应年均有效面积系数均大于0.90。在设计平板集热器件时,可参照该文研究结果,尽量达到对流热损失和遮光损失最小化。

分析太阳能平板集热器吸热板芯传热性能的一种简易方法

该文通过对太阳能平板集热器吸热板芯的传热分析 ,导出了一种能计算集热器吸热板温度场分布的简易方法 ,通过与有限元数值计算方法得出结果的对比 ,表明这种方法是可靠的 ,可以用于分析吸热板结构、气象参数等因素对太阳能集热器传热的影响 ,以利于优化集热器结构。

太阳能集热器研究进展

太阳能热水技术在太阳能利用技术中最为成熟、实际应用最多且在经济上能与常规能源竞争。太阳能集热器是太阳能热水器的核心部件,是用于吸收太阳辐射并使之转换为热能传递给热介质的装置。介绍了平板型太阳能集热器和真空管太阳能集热器,并对两者的优缺点进行对比,对其发展趋势进行了分析。

平板太阳能集热器热性能数学建模及模拟

以平板太阳能集热器作为研究对象,通过对平板太阳能集热器热性能进行理论推导,引入效率因子,构建更为准确、便捷的平板集热器的数学模型,进行计算机程序模拟。根据模拟数据得出吸热体板芯几何结构、板芯用材对平板太阳能集热器性能的影响。在不降低集热器效率因子的情况下,使翅片的单位面积质量降低45.8%;在材料消耗相同的情况下,集热器效率因子提高了0.03。

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。

平板太阳集热器热性能模拟分析

为对平板太阳集热器进行热性能分析及优化设计,建立平板太阳集热器的稳态性能数学模型,编制热性能模拟程序,分析环境参数、运行参数及结构参数对集热器瞬时效率的影响特性。模拟结果表明,环境温度升高、工质入口温度降低均可显著提高集热器瞬时效率;降低盖板发射率和吸热板表面发射率有利于提高集热器瞬时效率;减小工质质量流量和增大集热管间距会使集热器瞬时效率减小;环境风速变化对集热器瞬时效率影响较小;夹层间距变化对集热器瞬时效率的影响随工质入口温度的增大而增大;太阳辐射强度对集热器瞬时效率的影响跟集热器与环境间的热交换有关。