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.

Improving Heat Transfer in Parabolic Trough Solar Collectors by Magnetic Nanofluids

A parabolic trough solar collector(PTSC)converts solar radiation into thermal energy.However,low thermal efficiency of PTSC poses a hindrance to the deployment of solar thermal power plants.Thermal performance of PTSC is enhanced in this study by incorporating magnetic nanoparticles into the working fluid.The circular receiver pipe,with dimensions of 66 mm diameter,2 mm thickness,and 24 m length,is exposed to uniform temperature and velocity conditions.The working fluid,Therminol-66,is supplemented with Fe3O4 magnetic nanoparticles at concentrations ranging from 1%to 4%.The findings demonstrate that the inclusion of nanoparticles increases the convective heat transfer coefficient(HTC)of the PTSC,with higher nanoparticle volume fractions leading to greater heat transfer but increased pressure drop.The thermal enhancement factor(TEF)of the PTSC is positively affected by the volume fraction of nanoparticles,both with and without a magnetic field.Notably,the scenario with a 4%nanoparticle volume fraction and a magnetic field strength of 250 G exhibits the highest TEF,indicating superior thermal performance.These findings offer potential avenues for improving the efficiency of PTSCs in solar thermal plants by introducing magnetic nanoparticles into the working fluid.

Performance of a Combined Energy System Consisting of Solar Collector, Biogas Dry Reforming and Solid Oxide Fuel Cell: An Indian Case Study

An energy production system consisting of a solar collector, biogas dry reforming reactor and solid oxide fuel cell (SOFC) was assumed to be installed in Kolkata, India. This study aims to understand the impact of climate conditions on the performance of solar collectors with different lengths of parabolic trough solar collector (dx) and mass flow rate of heat transfer fluid (m). In addition, this study has evaluated the amount of H2 produced by biogas dry reforming (GH2), the amount of power generated by SOFC (PSOFC) and the maximum number of possible households (N) whose electricity demand could be met by the energy system proposed, considering the performance of solar collector with the different dx and m. As a result, the optimum dx was found to be 4 m. This study revealed that the temperature of heat transfer fluid (Tfb) decreased with the increase in m. Tfb in March, April and May was higher than that in other months, while Tfb from June to December was the lowest. GH2, PSOFC and N in March, April and May were higher than those in other months, irrespective of m. The optimum m was 0.030 kg/s.

Experiment and numerical simulation on flow and heat transfer in all-glass evacuated tube solar collectors

The experimental study of natural convection in allglass evacuated tube solar collectors is performed through the experimental platform of the solar-assisted fuel cell system.The experimental facility includes solar collectors with different length and diameter tubes, different coating materials, and with / without guide plates, respectively. Threedimensional mathematical models on natural and forced convections in the solar collectors are established and the experimental data is validated by field synergy and entransy principles. The results of natural convection show that the water temperature increases and thermal efficiency decreases gradually with the evacuated tube length. The thermal efficiency increases when absorption rates increase from 0. 95 to 1. 0 and emission rates decrease from 0. 16 to 0. 06. The thermal efficiency of solar collectors is increased after being equipped with the guide plate, which is attributed to the disappearance of the mixed flowand the enhancement of the heat transfer at the bottom of the evacuated tube. The results of forced convertion indicate that the Reynolds, Nusselt and entransy increments of the horizontal double collectors are higher than those of the vertical single collector while the entransy dissipation is lower than that of the vertical single collector. It is concluded that the solar collectors with guide plates are suitable for natural convection while the double horizontal collectors are suitable for forced convection in the thermal field of solar-assisted fuel cell systems with lowand medium temperatures.

Improving performance of flat plate solar collector using nanofluid water/zinc oxide

In this article,the effect of using water/zinc oxide nanofluid as a working fluid on the performance of solar collector is investigated experimentally.The volumetric concentration of nanoparticles is 0.4%,and the particle size is 40 nm,and the mass flow rate of the fluid varies from 1 to 3 kg/min.For this experiment,a device has been prepared with appropriate measuring instruments whose energy source is solar radiation.The solar energy absorbed by the flat plate collector is absorbed by the nanofluid of water/zinc oxide.The nanofluid is pumped to the consumer,a heat exchanger,where it heats the water.The temperature,radiation level,flow rate,and pressure in different parts of the device were measured.The pressure drop and the heat transferred are the most important results of this experimental work.The ASHRAE standard is used to calculate efficiency.The results showed that the use of water/zinc oxide nanofluid increases the collector performance compared to water.For 1 kg/min of mass flow rate,the nanofluids have a 16% increase in efficiency compared to water.From the results,it can be concluded that the choice of optimum mass flow rate in both water and nanofluid cases increases efficiency.

Solar Desalination with Latent Heat Storage Materials and Solar Collector

Availability of clean water is going to become one of biggest demands of the country. Even though there arc various technologies available for purification of water harnessing solar energy fits the purpose for future problems. Distillation is one of many processes available for water purification, and solar energy is one of several forms of heat energy that can be used to energize this process. In this review a study is made to enhance the productivity of the solar stills by connecting solar still with latent heat storage and solar air heater in series and other factors like improving evaporation rate by maintaining Low depth, more exposure area, heat addition by solar collector and presence of latent heat storage material, which is a paraffin wax as a integral part of still. Latent heat storage is one of the most efficient ways of storing thermal energy. Unlike the sensible heat storage method, the latent heat storage method provides much higher storage density, with a smaller temperature difference between storing and releasing heat. Further augmentation of the yield by scraps, pebble, and sand are added.

Enhanced efficiency in Concentrated Parabolic Solar Collector(CPSC) with a porous absorber tube filled with metal nanoparticle suspension

In this study, effects of different nanoparticles and porosity of absorber tube on the performance of a Concentrating Parabolic Solar Collector(CPSC) were investigated. A section of porous-filled absorber tube was modeled as a semi-circular cavity under the solar radiation which is filled by nanofluids and the governing equations were solved by FlexPDE numerical software. The effect of four physical parameters, nanoparticles type, nanoparticles volume fraction(φ), Darcy number(Da) and Rayleigh number(Ra), on the Nusselt number(Nu) was discussed. It turns out that Cu nanoparticle is the most suitable one for such solar collectors, compared to the commonly used Fe_3O_4, Al_2O_3, TiO_2.With the increased addition of Cu nanoparticles all the parameters φ, Da and Ra shows a significant increase against the Nu, indicates the enhanced heat transfer in such cases. As a result, low concentration of Cu nanoparticle suspension combined with porous matrix was supposed to be beneficial for the performance enhancement of concentrating parabolic solar collector.

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.

Dynamics and control of a solar collector system for near Earth object deflection

A solar collector system is a possible method using solar energy to deflect Earth-threatening near-Earth objects.We investigate the dynamics and control of a solar collector system including a main collector （MC） and secondary collector （SC）.The MC is used to collect the sunlight to its focal point,where the SC is placed and directs the collected light to an asteroid.Both the relative position and attitude of the two collectors should be accurately controlled to achieve the desired optical path.First,the dynamical equation of the relative motion of the two collectors in the vicinity of the asteroid is modeled.Secondly,the nonlinear sliding-mode method is employed to design a control law to achieve the desired configuration of the two collectors.Finally,the deflection capability of this solar collector system is compared with those of the gravitational tractor and solar sail gravitational tractor.The results show that the solar collector is much more efficient with respect to deflection capability.

Highly efficient energy harvest via external rotating magnetic field for oil based nanofluid direct absorption solar collector

Nanofluids based direct absorption solar collectors(DASCs) are considered as the important alternative for further improve the utilization of solar energy. However the low-quality energy and aggregation of nanoparticles obstructs their large-scale application. In this work, a new method of using magnetic nanofluids in DASCs is proposed. By this method, not only high-quality energy is got as well as the problems of blockage and corrosion in heat exchanger are well avoided. The result shows that the maximum temperature can reach 98℃ under 3 solar irradiations and the photothermal conversion efficiency can be further increased by 12.8% when the concentration is 500 ppm after adding an external rotating magnetic field. The highest viscosity of working fluid reduced by 21% when the concentration is 500 ppm at 95℃ after separating the Fe_(3)O_(4)@C nanoparticles from the nanofluids via magnetic separation technology. Meanwhile, the obtained pure base liquids with high temperature flow to heat exchanger, which also reduces the flow resistance in pipeline and avoids the problems such as blockage and corrosion in heat exchanger. This research promotes a new way for the efficient utilization of solar energy.

Energy and Cost Analysis of Processing Flat Plate Solar Collectors

In this work,a life cycle analysis is accomplished for flat plate solar collectors.The purpose of this investigation is to predict the energy consumption during the manufacturing processes that results in carbon dioxide emissions.Energy consumption and system efficiency enhancement will be studied and predicted.CES EduPack software is used to perform the analysis of the currently commercial system,and the suggested changes are implemented to increase the efficiency and make the comparison.Even though cost analysis is done,the priority of selection is given to the most energy conserving and environmentally friendly alternative.However,if the compared alternatives result in the same energy consumption and CO_(2)emissions,the cost analysis would be a better approach.It can be stated that flat plate solar collectors are sustainable and renewable energy systems that do not produce CO_(2)emissions during their active usage,but the manufacturing processes they undergo during the design contribute to the greenhouse gasses emission.

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.

Theoretical and Experimental Study of a Cylindro-Parabolic Solar Collector

This article outlines the theoretical and experimental performance studies of a cylindro-parabolic solar collector. The theoretical study consists on the establishment, through mass and energy balances, of a mathematical model to control the exiting temperature of the heating fluid as well as the temperatures of the absorber and the glass. The experimental level investigates the influence of the solar absorber tube diameter on the performances of the driving device. Several experiments were made in order to know the possibility to reach temperatures being able to ensure for example the ammonia vaporization in the generator of a solar absorption refrigeration system. These experiments were carried out under various operating and climatic conditions. The results are presented and discussed.

Solar Collectors of Buildings Facade Based on Aluminum Heat Pipes with Colored Coating

A variety of liquid thermal solar collectors designs used for water heating have been developed by the previous researchers. But the majority of them do not meet the requirements on small weight, easy assembling and installing, versatility, scalability and adaptability of the design, which are particularly important when they are facade integrated. In order to avoid the above mentioned drawbacks of the liquid thermal collectors, the authors propose to apply to them extruded aluminum alloy made heat pipes of originally designed cross-sectional profile with wide fins and longitudinal grooves. Such solar collectors could be a good solution for building facade and roof integration, because they are assembled of several standard and independent, hermetically sealed and light-weight modules, easy mounted and ＂dry＂ connected to the main pipeline. At that, their thermal performances are not worse than of the other known ones made of heavier and more expensive copper with higher thermal conductance, or having entire rigid designs. Some variants of the developed solar collectors shaping of the assembled modules for building facade or roof integration are proposed. Variously colored coatings to the absorbers are developed and made of carbon-siliceous nano-composites by means of sol-gel method. Their optical performances were compared with ＂anodized black＂. It is stated that colored coatings have a good prospect in thermal SCs （solar collectors） adaptation to building facades decoration, but the works on study and upgrade of their performances should be continued.

Fabrication of Multilayer Optical interference Filter as Colored Glazed Buildings Fa（;ades for Thermal Solar Collectors Using MgF2/SiO2

A simple idea to obtain a desired color that hiding the black color, and the visibility of tubes and corrugations of the metal sheet （absorber） of the thermal solar collectors which is consider the main obstacle to facade integration buildings of solar thermal collectors will be presented in this study by designing a multilayer optical interference filter during RF magnetron sputtering process. This filter work as antireflection coating in the near IR region and also includes a high colored reflectance at a specific wavelength in the visible region, this is to gain an esthetic aspect for the thermal solar collector which can be used as building facades by employing appropriate dielectric materials with high refractive index （H） like SiO2 and low refractive index （L） such as MgF2 which they deposited on glass substrate for quarterwave thickness and for the optical model air//HL//glass.

Heat Transfer Optimization in Air Flat Plate Solar Collectors Integrated with Baffles

This paper presents an experimental analysis for comparisons of conventional flat plate solar collectors and collectors integrated with different numbers of baffles. Heat transfer between absorber plate and drying fluid (air) has been one of the major challenges in the design and operations of the indirect solar dryer systems. In this experiment, efficiency of air flat plate solar collector integrated with 2, 3, 4 and 8 baffles was studied and compared with the ordinary collector. The results showed that integrating solar collector with baffles significantly increased the efficiency of the system. It was noted that collector with 2, 3, 4 and 8 baffles had a mean efficiency of 29.2%, 31.3%, 33.1% and 33.7% respectively while with no baffles was 28.9%. The analysis showed that when there were less than four baffles in the collector, heat transfer was dominant over pressure drop and hence high efficiency. However, when the number of baffles exceeded four, the effect associated with an increase in pressure drop highly observed compared to heat transfer coefficient, thus resulted to insignificant increase in efficiency. Therefore, the optimum number of four baffles was commended for the designed model for optimum efficiency.

Thermal performance of integration of solar collectors and building envelopes

The integration of building with solar collector was studied. The theoretical model of integration of building envelopes and flat plate solar collectors was set up and the thermal performance of integration was studied in winter and summer,and compared to envelopes without solar collectors. The results show that the solar collection efficiency is raised in the integration of building envelopes and solar collectors with the air layer doors closed. This is true whether in winter or summer. The increment is higher as the inlet water temperature increases or the ambient temperature is low. In winter,the heat loss is significantly reduced through integration of the building envelopes and solar collectors with the closed air layer doors. The integration with the open air layer door is worse than that without collectors. In summer,the heat gains of the integration of envelopes and solar collectors are more obviously reduced than envelopes without collectors,the integration with the open air layer door is a little better than the closed one,but the difference is very small.

Multi-factor Effects on Layout of Solar Collector

Considering the influencing factors of the layout of solar collectors such as the tilt angles,azimuth angles,spacing between collectors and the number of collector rows,a mathematical model of the collected energy of the solar collector with limited area on the horizontal plane is established.Two different optimized models including the cost benefit model and the minimum annual auxiliary heating energy model are conducted in this paper.The results show that,the collected energy in a year could increase with the increase of the number of collector rows.And the collected solar radiation in a year increases firstly and then decreases with the increase of the collector tilt angles.Furthermore,the collected solar radiation in a year increases firstly and then decreases with the continuous increase of the azimuth angles from -90° to 90°.Taking Nanjing city of China as an example,based on the optimized objective of maximum benefit,the optimal layout of the solar collector array in the area of 200 m2 should include:the number of collector rows is 8,the tilt angle is 40° and the azimuth angle is 0°.Meanwhile,the optimal methods for the optimized objective of minimum annual auxiliary heating energy should include:the number of collector rows is 9,the tilt angle is 50°,and the azimuth angle is 0°.

Numerical Investigation of Wind Flow around a Cylindrical Trough Solar Collector

The goal of this study is to model the effects of wind on Cylindrical Trough Collectors (CTCs). Two major areas are discussed in this paper: 1) heat losses due to wind flow over receiver pipe and 2) average forces applied on the collector’s body. To accomplish these goals a 2D modeling of CTC was carried out using commercial codes with various wind velocities and collector orientations. Ambient temperature was assumed to be constant at 300 K and for specific geometries different meshing methods and boundary conditions were used in various runs. Validation was done by comparing the simulation results for a horizontal collector with empirical data. It was observed that maximum force of 509.1 Newton per Meter occurs at +60 degrees. Nusselt number is almost the constant for positive angles while at negative angles it varies considerably with the collector’s orientation.

Optimum Design of Tilt Angle and Horizontal Direction of Solar Collectors under Obstacle’s Shadow for Building Applications

Solar collectors can provide clean, renewable, and domestic energy. The tilt angle and horizontal direction of solar collectors significantly affect its efficiency. There are many good methods to search the optimum tilt angle and horizontal direction to realize the maximum total radiation on the solar collector within a particular day or a specific period. However, it is hard to realize it when solar collectors are placed under obstacle’s shadows;especially when some obstacles, such as trees, have irregular shapes. This paper presents algorithms to achieve the best tilt angle and horizontal direction for solar collector’s performance under the free-form surfaces 3D obstacle’s shadow. The solution process is composed of 4 steps. First, it creates a 3D scene, in which a unique color is given to the solar collector. Second, it employs orthographic projection from the point of view to get an image of the scene. Third, the number of pixels is used to represent the efficiency of the solar collector by counting the pixels of the unique color. Fourth, the efficiency of solar collector in each direction in a period of time is calculated with many images to further select the best direction.