Testing Of Collector Research Articles

Parameter identification and uncertainty evaluation in quasi-dynamic test of solar thermal collectors with Monte Carlo method

This work presents a comparison between two methods used for parameter identification and calculation of parameter uncertainty applied to the measured data of solar thermal collectors when tested according to ISO 9806:2017. One method is using a weighted least square (WLS) fit and the partial derivative approach described in the GUM (the Guide to the Expression of Uncertainty in Measurement). The second is using the Monte Carlo (MC) method, also described in GUM. Uncertainty evaluation by Monte Carlo method is based on a probabilistic approach and is an alternative way for identification of parameters and determination of the uncertainties. In this work the results were obtained according to Quasi-Dynamic Test (QDT) method for a flat plate collector and an evacuated tubular collector. The least squares (LS) method and a nonlinear regression method (MPFit) are used in the identification of parameters for each iteration of the MC method. For the implemented MC method computation times are also discussed. One disadvantage of the MC method is the computation time which depends on the number of samples in the experimental test quantity files, however with this study we think that the advantages of the MC method outweigh the disadvantages, and it is useful even as a complementary tool in QDT testing of collectors.

Development and Testing of a Low-Concentrating Photovoltaic-Thermal Collector

Testing and certification of solar technologies are crucial to characterize and guarantee their performance under different operating conditions. These procedures are even more relevant for novel solar technologies such as low-concentrating photovoltaic-thermal (LCPV-T) collectors. This paper presents the development and early-stage testing of a LCPV-T collector in a newly established testing laboratory based on a comprehensive review of international standards. The testing facility was designed, built, and commissioned in the north of Mexico, and it is the first of its kind in Latin America. It allows us to evaluate the thermal and electrical performance of LCPV-T collectors with a maximum area of 6 m2 and electrical peak power of 3 kWe. The operational temperature of the LCPV-T collectors can reach up to 120°C and can be characterized under steady-state and quasi-dynamic testing conditions.

A holistic methodology for designing novel flat plate evacuated solar thermal collectors: Modelling and experimental assessment

This paper presents a comprehensive analysis of the design, implementation, experimentation, and optimization of a novel evacuated flat-plate solar thermal collector characterized by a vacuum level between the glass cover and the absorber plate. The paper addresses different research themes, primarily focusing on developing a low-cost evacuated solar thermal collector with a high innovation level. Additionally, it introduces a comprehensive approach for the conceptualization, design, fabrication, testing, and optimization of solar thermal collectors. Specifically, this study aims to highlight the characteristics of a vacuum-enhanced solar thermal collector and demonstrate a step-by-step process involved in its design, fabrication, testing, and optimization. The proposed methodology is based on the adoption of two software tools and an extensive experimental analysis: the commercial software ANSYS is utilized for structural analysis, while MatLab is employed to develop a suitable mathematical tool for assessing the energy performance of the system and optimizing it. The outcomes show the reliability of the methodology and the performance of the low-cost evacuated solar thermal collector under different vacuum levels, providing insights into energy, economic, and environmental aspects. This work innovates by presenting a thorough analysis covering all solar thermal collector production phases, from conceptualization to optimization. The conclusions highlight the production of a reliable approach, and proof-of-concept results demonstrate how increasing the vacuum level enhances the thermal efficiency of a solar collector.

Testing of uncovered solar thermal collectors under dynamic conditions and identification of performance parameters - for nocturnal radiative cooling applications

This paper presents the first part of a research-work conducted at the University of Applied Sciences (HFT-Stuttgart). The aim of the research was to investigate the potential of low-cost renewable energy systems to reduce the energy demand of the building sector in hot and dry areas. Radiative cooling to the night sky represents a low-cost renewable energy source. The dry desert climate conditions promote radiative cooling applications. The system technology adopted in this work is based on uncovered solar thermal collectors integrated into the building's hydronic system. By implementing different control strategies, the same system could be used for cooling as well as for heating applications. This paper focuses on identifying the collector parameters which are required as the coefficients to configure such an unglazed collector for calibrating its mathematical model within the simulation environment. The parameter identification process implies testing the collector for its thermal performance. This paper attempts to provide an insight into the dynamic testing of uncovered solar thermal collectors (absorbers), taking into account their prospective operation at nighttime for radiative cooling applications. In this study, the main parameters characterizing the performance of the absorbers for radiative cooling applications are identified and obtained from standardized testing protocol. For this aim, a number of plastic solar absorbers of different designs were tested on the outdoor test-stand facility at HFT-Stuttgart for the characterization of their thermal performance. The testing process was based on the quasi-dynamic test method of the international standard for solar thermal collectors EN ISO 9806. The test database was then used within a mathematical optimization tool (GenOpt) to determine the optimal parameter settings of each absorber under testing. Those performance parameters were significant to compare the thermal performance of the tested absorbers. The coefficients (identified parameters) were used then to plot the thermal efficiency curves of all absorbers, for both the heating and cooling modes of operation. Based on the intended main scope of the system utilization (heating or cooling), the tested absorbers could be benchmarked. Hence, one of those absorbers was selected to be used in the following simulation phase as was planned in the research-project.

Low-Cost Data Acquisition System for Solar Thermal Collectors

Solar thermal collectors are among the most popular renewable energy research subjects. Automatic Data Acquisition Systems (ADAS) have greatly facilitated their experimental testing, but their high cost is a drawback. In this paper, we present the design and testing of a decentralized, low-cost alternative ADAS based on the ESP32 microcontroller and on open-source software. The proposed system can be used for the experimental characterization of water (or air) operated solar thermal collectors in accordance with the ISO 9806:2017 requirements, but it is also compatible with sensors with lower specifications. We present also its performance results when applied for the testing of a solar thermal collector.

Experimental study and performance testing of a novel parabolic trough collector

Experimental study and performance testing of a novel parabolic trough collector

Novel incident angle modifier model for quasi-dynamic testing of flat plate solar thermal collectors

There are two accepted standard methodologies to characterize the performance of solar thermal collectors: Steady-State Testing (SST) and Quasi-Dynamic Testing (QDT). This last methodology requires a model for the Incident Angle Modifier (IAM). In this article a new model for the IAM is presented to be used in the quasi-dynamic testing of Flat Plate Collectors (FPC), inspired in the interpolation procedure indicated by the ISO-9806 (2017) standard for SST. The model considers the IAM as a continuous and piecewise linear function and uses its nodes values at each 10° as adjustable parameters. The model’s performance is compared against four other widely-used pre-existing models, being more precise and showing a better overall agreement in the whole incident angle’s range. It is observed that the proposal is also more reliable, as it has a lower sensitivity to experimental data variability. This second characteristic allows to reduce test’s duration because it eliminates the ISO-9806 (2017) requirement of testing the collector in the morning and afternoon, in a balanced manner. Although the specific implementation of this work is for FPC, the model can be extended to other solar collector technologies as it has the ability to represent the IAM variability for all incident angles.

The International Standards for Solar Thermal Collectors and Components as a Medium of Quality Assurance

Within this publication a detailed overview about the national and international solal‘t1lel1nai standards is made. The various tests are described and a cross reference list for comparing the different standards is given. Moreover a certification model is presented and the advantage of third party assessment is carried out. The requirement for a solar thermal test laboratory to conduct independent third party assessment by means of an ISO/IEC17065 accreditation is given. Finally the concept of a quality system for solar thermal markets is explained and major advantages are outlined. Solar thermal systems and their components are described in various national and international standards. In Europe the standard EN12975 de?nes the regulations and requirements for solar thermal collectors. The standard EN12976 is established for the evaluation of factory made solar thermal systems. The EN12977 is the state of the art standard for the evaluation of custom build systems. Nowadays in Libya the standard ISO9806 for solar collectors and the standard ISO9459 for domestic water heating systems de?ne the regulations and requirements for solar thermal collectors and systems. In the meanwhile, empowered Center for Renewable Energy and Energy Ef?ciency Certi?cation Body is under construction. This body is working now to set the minimum requirements of the testing facilities of solar thermal systems. The international standard for collector testing is the ISO9806 and the standard ISO9459 Part2,4,5 for domestic water heating systems. Within the year 2013 a revision of the ISO9806 will be published and, for the ?rst time, a consistent harmonized standard for the main solar thermal markets will be set in force. Besides the various standards for solar thermal products a meaningful element for the quality assurance and the customer protection is third party certi?cation. Third party certi?cation involves an independent assessment, declaring that speci?ed requirements regarding a product are ful?lled. In a certi?cation process based on speci?ed certi?cation rules an authorized certi?cation body is con?rming that a solar thermal product has passed performance tests, reliability tests and further requirements according to the standards. In Europe a certi?cation body holds an accreditation according to EN45011. At international level the standard ISO/IEC17065 is in force. Test results as a basis for product certi?cation are determined by solar thermal test laboratories. The implementation and the business operation of such a solar thermal test laboratory is an important element within the national/regional solar thermal market. To ensure the quality of the products and to attend the role of an observer on the market, the test facility has to ful?ll a number of requirements. Besides the necessary technical equipment and the implementation of tests in accordance with the various national and international standards, the laboratory shall realize a quality management system to guarantee the quality of tests and services. Based on the technical equipment, the testing scope and an implemented Quality Management System (QMS), the test laboratory can achieve an accreditation according to ISO/IEC17025 as basis for independent third party testing. Independent testing and evaluation of solar thermal collectors and components like hot water stores and controllers offers an important medium for quality assurance. To guarantee a high degree of product quality and consumer protection a quality system for the solar thermal market is necessary. Core of the quality assurance of a functioning solar thermal market are the national standards body, which is developing standards and regulations as a working basis ill technical committees, the national metrology institute that guarantees the traceability of measurements on fundamental and natural constants, and ?nally the national accreditation body which ensures the conformity of the various actors to a speci?c standard. Laboratories work closely with the certi?cation authorities and apply the developed speci?c norms and standards. The certi?cation bodies must ensure the conformance of their test laboratories with the standard ISO/IEC17025, which include the quality standard ISO 9001:2008 and also include additional requirements. The traceability of the metrics of solar thermal testing laboratories is usually made with the help of calibration laboratories that are specialized on certain measurements. Those are also accredited and ensure the traceability of their measurements to the national meteorology institute. Other stakeholders are the group of importers and exporters and foreign investors who are on the national market in entrepreneurial activities, as well as the group of consumer organizations that represent the interests of customers. By means of good networking of stakeholders and focusing 011 the quality process, a high-quality and ?ourishing solar thermal market can be created.

ALTERNATIVE METHOD OF NON-DESTRUCTIVE TESTING FOR NUCLEAR POWER PLANT

This study presents the results of electrophysical non-destructive testing of collectors welded joints to the body of steam generators PGV 1000Mof the reactor WWER-1000. The studied steam generators located in the Resource Сenter of National Research Nuclear University MEPhI at the site of reactors construction factory “Atommash” in Volgodonskcity-Russia. The primary loop collector was welded to the body of steam generators PGV 1000Mand the technical condition of welded joints was investigated by electrophysical non-destructive testing (EPhT). In steam generatorsmay appear corrosion and cracks due to corrosive environment and effect of stresses however,EPhTcan detect early stages of cracks. The study highlights the theoretical part of electrophysical diagnostics and control method, using modern mathematical signals analysis, and issues related to the practical implementation of EPhT in the factory. The novel alternative method of non-destructive testing can be used in diagnostic oil and gas pipelines, elements of complex technical structures and industrial equipment. It can be used in many industries where it is necessary to process control of the entire structure or its individual parts under operating conditions. Based on control results, potentiograms were constructed for various structural levels of the diagnostic signal. The results of controlled welded joints in steam generators showed their satisfactory condition.

Testing of New Collectors for Concentration of Fluorite by Flotation in Pneumatic (Modified Hallimond Tube) and Mechanical Cells

In this study, two new collectors for fluorite flotation DP-OMC-1033 (DP-I) and DP-OMC-1234 (DP-II) were tested and compared with oleic acid (OA), sodium oleate (SO) and potassium oleate (PO). According to fluorite grade and fluorite metallurgical recovery, the effect of each collector was determined, both in mechanical and pneumatic cell flotation. The effect of temperature on the collectors from 25 to 55 °C was studied. Flotation tests showed that the best results in terms of fluorite metallurgical recovery were 82.8% and 87.9% for new collectors DP-I and DP-II respectively, for a dosage of 100 g/t and using pneumatic cell. Additionally, in terms of fluorite grade, DP-I showed the best results, achieving 79.7% of CaF2 in roughing step for a dosage of 100 g/t. Fluorite metallurgical recovery and grade in concentrate increased for OA, SO and PO with increasing temperature. However temperature did not have a significant effect on both metallurgy recovery and CaF2 grade using DP-I and DP-II, so the process can be effective at 25 °C reducing operating costs.

Systematic testing of hybrid PV-thermal (PVT) solar collectors in steady-state and dynamic outdoor conditions

Hybrid photovoltaic-thermal (PVT) collectors have been proposed for the combined generation of electricity and heat from the same area. In order to predict accurately the electrical and thermal energy generation from hybrid PVT systems, it is necessary that both the steady-state and dynamic performance of the collectors is considered. This work focuses on the performance characterisation of non-concentrating PVT collectors under outdoor conditions. A novel aspect concerns the application of existing methods, adapted from relevant international standards for flat plate and evacuated tube solar-thermal collectors, to PVT collectors for which there is no formally established testing methodology at present. Three different types of PVT collector are tested, with a focus on the design parameters that affect their electrical and thermal performance during operation. Among other results, we show that a PVT collector suffers a 10% decrease in thermal efficiency when the electricity conversion is close to the maximum power point compared to open-circuit mode, and that a poor thermal contact between the PV laminate and the copper absorber can lead to a significant deterioration in thermal performance. The addition of a glass cover improves the thermal efficiency, but causes electrical performance losses that vary with the glass transmittance and the solar incidence angle. The reduction in electrical efficiency at large incidence angles is more significant than that due to elevated temperatures representative of water-heating applications. Dynamic performance is characterised by imposing a step change in irradiance in order to quantify the collector time constant and effective heat capacity. This paper demonstrates that PVT collectors are characterised by a slow thermal response in comparison to ordinary flat plate solar-thermal collectors, due to the additional thermal mass of the PV layer. A time constant of ∼8 min is measured for a commercial PVT module, compared to <2 min for a flat plate solar-thermal collector. It is also concluded that the use of a lumped, first-order dynamic model to represent the thermal mass of the PVT collector is not appropriate under certain irradiation regimes and may lead to inaccurate predictions of the system performance. This paper outlines a procedure for the testing and characterisation of solar collectors, provides valuable steady-state and dynamic performance characterisation data for various PVT collector designs, and also provides a framework for the application of this data in a system model to provide annual performance predictions in a range of geographical settings.

Methods for the development and testing of polymeric hybrid photovoltaic thermal (PVT) collector for indoor experiments

The purpose of this article is to present the methods for the development and testing of polymeric hybrid Photovoltaic Thermal (PVT) collectors for indoor experiments. Polymeric material has been used in hybrid PVT collectors and even longer used on flat plate collectors. We have developed a method to make a hybrid PVT collector with an absorber made of a polymethyl-methacrylate (PMMA) and combined with a copper sheet. To understand the details of the thermal and electrical performance, we have developed a method to test this PVT collector by conducting a series of experiments by varying the mass flow rate, irradiance, and inlet water temperature. The results showed that PMMA as a thermal absorber with a copper sheet can provide a beneficial cooling effect of around 80% thermal efficiency and a 0.03 %/oC decrease in electrical efficiency.•This method makes PVT collector hybrids easily and cheaply using simple equipment.•This method provides simple technical testing of hybrid PVT collectors•This method can be applied to make a larger hybrid PVT collector with modular.

Coupled optical-thermal modeling, design and experimental testing of a novel medium-temperature solar thermal collector with pentagon absorber

The simulation, prototyping and testing of novel medium-temperature solar collector is elaborated in this paper. First, selection of higher concentration reflector (1.4×) with optimized absorber geometry (pentagon) is justifiedfor medium temperature application (100–300 °C). Afterwards, the collector with 6 evacuated tubes, CPC reflector and manifold is designed and coupled optical-thermal simulation is studied using finite element method implemented in COMSOL Multiphysics in order to predict optical and thermal efficiency of the system before prototyping. Finally, the proposed medium-temperature collector is tested with selective-coated pentagon absorber in the real condition at University of California, Advanced solar technology institute. The experimental and numerical results underscore a close similarity which the optical efficiency of 64% and thermal efficiency of 50% at 200 °C are achieved both numerically and experimentally. At the end, the proposed collector is compared with all major commercial collector both in performance and cost. The levelized cost of heat for a single collector is calculated as 3.1 cents/kWh. This price is cheaper than all categories of solar collector (Evacuated flat plat, Evacuated Tube, Fresnel lenses and parabolic trough) for medium temperature application (200 °C). Also, LCOH of proposed collector indicates the potential for solar thermal collector to challenge natural gas as California’s primary heat source in the near future.

Fabrication and Testing of Solar Heat Collector by using alternative Absorber and Glaze Materials

Fabrication and Testing of Solar Heat Collector by using alternative Absorber and Glaze Materials

Heat Transfer Coefficient from the Sheet-Piped Light-Absorbing Panels of the Flat-Plate Solar Water-Heating Collectors to the Heat Transfer Fluid in Their Heat-Removing Channels

It has been proposed to introduce a new parameter into the practice of the heat calculation and testing of the flat-plate solar water-heating collectors (FSWHCs)—the coefficient of heat transfer from the light-absorbing panel (LAP) to the heat transfer fluid in its internal heat-exchange channels (HECs) reduced to the unit area of the frontal surface of their cases. The mechanism of the formation of this parameter is studied, the design expression is derived, and a practical example of the calculation to define its value is performed. The structures of the flowing LAPs of a sheet-piped thin parallelepiped form are selected as the objects of the investigation. The reliability of the results of the investigations is proved by comparing the values of the specific (relative to the area unit of the frontal surface of the case) heating efficiency of the collector obtained based on the various formulas.

Design, fabrication and testing of solar concrete collector at Kakinada

Design, fabrication and testing of solar concrete collector at Kakinada

Development and testing of a compound parabolic collector for large acceptance angle thermal applications

Development and testing of a compound parabolic collector for large acceptance angle thermal applications

Enhancement of spectral absorption of solar thermal collectors by bulk graphene addition via high-pressure graphite blasting

This work presents the results of construction and testing of a flat plate thermal solar collector with an absorber section that has enhanced radiative properties through the modification of its surface properties. A copper oxide layer is grown on top of the copper absorber by chemically treating it in an ammonia atmosphere. Then, a novel graphene mechanical deposition technique is employed that uses compressed air to deposit few layer graphene on top of the copper oxide substrate. In total, three absorbers are made, one features the copper oxide layer, the second has graphene on top of copper oxide and the third is the reference absorber covered with a black matt paint. The radiative properties of the absorbers are assessed, as well as their thermal efficiencies. The best performance was recorded for the graphene-clad copper oxide collector, with a maximum efficiency of 69.4% compared with an efficiency of around 39.5% for the reference collector.

Experimental testing of ceramic solar collectors

An alternative to traditional solar collectors with absorbers made of metal or plastic can be panels which have their whole structure made of ceramics. The paper presents the results of the testing of ceramic solar collectors. The experimental research was carried out in summer 2016 in normal operating conditions. Rise in temperature of the fluid flowing through the collector was measured. The maximum value of this parameter did not exceed 7.5°C and the maximum power output extracted from 1m2 of the ceramic solar collector under test was equal to 650W/m2. The thermal characteristic of ceramic solar collectors was determined as the relationship between efficiency and the reduced temperature difference. The straight line corresponding to this characteristic is described by zero-loss collector efficiency coefficient equal to 0.8332 and heat loss coefficient equal to 16.332. Based on the analysis of the test results, it can be concluded that, in spite of some disadvantages, ceramic collectors can compete with traditional solar panels currently available on the market.

Determination of Optimal Position of Solar Trough Collector

This work deals with the utilization of solar energy using parabolic trough collector. Testing of solar collector manufactured according our own design has taken place in Žilina. Collector consists of firm frame attached to concrete floor, which limits the sun tracking to one axis. Trough of the collector is oriented as east-west position with a small deviation of approximately 10°. To obtain the best performance parameters of the collector, the optimal position of trough to the sunlight must be maintained. The aim of the work is to calculate the tilt angle for specific day and corresponding time of a day.