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A new TRNSYS type for thermosiphon flat-plate solar thermal collectors: validation and optimization procedure
摘要： This paper presents a new TRNSYS Type (called Type 99) which can be used for the energy assessment of thermosiphon Flat-Plate solar thermal Collectors (FPCs) for water heating. The accuracy of this new type is higher than the standard type (Type 45a) available in TRNSYS library, since the density and specific heat of water are estimated according to the operating fluid temperature. The results of a suitable experimental campaign are also presented for different commercial FPCs system layouts. The developed Type 99 is successfully validated, proven by the very good agreement achieved between the simulation and experimental results. By the new Type 99 a suitable Design of Experiment (DoE) analysis is carried out with the aim to assess the design and operating parameters mostly affecting the energy and economic performance of two types of FPCs. Specifically, collector pipe diameters, slope, storage tank volume, and thermal insulation thickness are investigated. The analysis is carried out for three case studies which refer to residential Domestic Hot Water (DHW) production applications and to three different European weather zones (Freiburg, Naples and Larnaca). For these case studies an optimization procedure is also carried out by varying the same design and operating parameters for two different objective functions: best energy behaviour [maximum Primary Energy Saving (PES)] and best economic performance [minimum Simple Pay Back (SPB)]. Interesting novel design criteria and encouraging economic results are obtained.
关键词： economic assessment,DoE analysis,Building solar thermal systems,dynamic energy performance analysis,experimental validation
更新于2025-09-23 15:22:29
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Power modulated fiber-optic loop sensor: theoretical and experimental investigation
摘要： The present work is focused on discussing a power modulation based sensor created using a single mode optical fiber. The sensing principle allows making displacement measurements with high accuracy and in a large measurement range due to the presence of resonance peaks in the transmitted intensity. A theoretical model is developed for the Fiber-Optic Loop Sensor (FOLS) and is validated with experimental data. The results show close matching between theoretical predictions and experimental results, allowing the use of the sensor for displacement measurement.
关键词： experimental validation,Fiber optic loop sensor,deformation,theoretical model,power modulation
更新于2025-09-23 15:21:01
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Determination of electrical characteristics and temperature of PV modules by means of a coupled electrical-thermal model
摘要： Photovoltaic (PV) modules are commonly tested under standard test conditions. However, the performance of the PV module is highly dependent on the location, climate condition, and sun spectrum. Simulation is one of the inexpensive and practical approaches to estimate the performance of PV modules under different climatic conditions. Modeling of PV modules can be complex because different physical phenomena must be coupled and interact with each other. There are several existing multi-physic models, but they are either complex such as numerical models or highly simpli?ed with a lot of assumptions. In this work, we introduce a thermal-electrical model to evaluate the performance of PV modules under different climate conditions based on a previously developed optical-electrical model. The model calculates the electrical parameters and temperature of the PV module after the module reaches the steady-state condition. The temperature, heat ?ow of all layers of the module, and the heat transfer thermal resistances can be determined. Comparison of the simulation and experimental results shows a deviation of around 1%, which indicates that the simulation and experimental results are in good agreement.
关键词： climate conditions,simulation,thermal-electrical model,experimental validation,Photovoltaic modules
更新于2025-09-19 17:13:59
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Numerical modelling and experimental validation of thermal history of titanium alloys in laser beam melting
摘要： During selective laser melting processes parts will heat up with each layer depending on the geometry and surrounding powder material. This leads to process boundary conditions that are not certainly defined and can induce unstable melt pool sizes. These will have an influence on surface roughness and dimensional accuracy. One way to deal with this is an individual adaptation of process parameters, but without knowing the exact thermal boundary conditions in each layer one will not be able to adapt the parameters properly. In this paper a model for prediction of the macroscopic temperature history is presented and experimentally calibrated. A sample with characteristic features like overhanging’s was designed. These samples were produced by selective laser melting and simultaneously monitored by an infrared camera to calibrate the boundary conditions of a numerical model. This lays the foundation for part individual adaption of process parameters to improve the quality of SLM parts.
关键词： Experimental Validation,Numerical Modelling,Titanium Alloys,SLM
更新于2025-09-12 10:27:22
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Scintillation experiments with non-uniformly and uniformly correlated spatially partially coherent laser beams propagating underwater
摘要： We report on experiments where non-uniformly correlated (NUC), Gaussian Schell (GSM) and Multi-Gaussian Schell (MGSM) model spatially partially coherent laser beams were propagated underwater. Two scenarios were explored: still water and mechanically agitated water. The main objective of our study was the experimental comparison of the scintillation performance among beams with different correlation functions. The results show generally increased absolute values of scintillation index for NUC beams as compared with GSM and MGSM beams. We hypothesized that this effect is related to the method of NUC beams generation. It should be noted, that the presented results document only the given experimental scenarios and show the relative comparison between GSM, MGSM and NUC beams with Gaussian used as a turbulence level benchmark. Further investigation is necessary to broaden the scope of our explorations of the propagation of uniformly correlated spatially partially coherent as well as non-uniformly correlated beam classes.
关键词： multi-Gaussian Schell model beam,Non-uniformly correlated,partial spatial coherence,scintillation,experimental validation,underwater laser propagation
更新于2025-09-12 10:27:22
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Coupled electrical-thermal modelling of photovoltaic modules under dynamic conditions
摘要： This paper presents a coupled electrical-thermal model for solar photovoltaic (PV) modules, under an unsteady state and various conditions, including ambient temperature, solar radiation and wind velocity. Validation shows that the electrical and thermal models present high agreement with the experimental data. The developed model after validation is then applied to investigate the distribution of thermal resistance, the in?uence of environmental conditions and cooling methods. Results show that the radiative and convective thermal resistances play a signi?cant role in PV electrical-thermal performance, while conductive thermal resistance can be neglected for simpli?cation in some cases. The results also demonstrate the effects of weather conditions including solar radiation, ambient temperature and wind velocity on PV performance vary and they need to be selected carefully during parameters design. Moreover, a dynamic estimation of different seasons and a long-term evaluation of an entire year for a speci?c PV array have been done to assess the performance of the coupled model. The simulated results are in good agreement with the experimental data in spite of the weather conditions, in which the relative errors of daily energy in four different seasons are just 1.06%e6.17%, while the average monthly energy based on the proposed model (1185.4 kWh) only deviates 4.66% from that extracted by PVsyst software (1132.6 kWh), which both verify the accuracy of the proposed model again.
关键词： Experimental validation,Performance evaluation,Photovoltaic (PV) module,Coupled electrical-thermal model
更新于2025-09-11 14:15:04
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Thermal modelling of a flat plate solar collector with latent heat storage validated with experimental data in outdoor conditions
摘要： This paper presents a thermal modelling strategy to evaluate the performance of latent heat storage technique in a ?at plate solar collector (FPSC) with integrated phase change material (PCM). A thermal dynamic model is developed based in simpli?ed semi empirical correlations and includes heat transfer by conduction, convection and radiation in each part of the device. Melting process of the PCM is described with energy balances for a set of discrete spatial layers to calculate temperature and liquid fraction. The model is validated with experimental data gathered under outdoor conditions from a real ?at plate solar collector prototype modi?ed to incorporate PCM containers between the absorber plate and the insulation. As result of the validation process, the model shows the capability to estimate the global thermal performance of the device with good accuracy compared with the experimental measurements and using minimal computational resources. Comparisons between estimations of the model and test data are presented for 20 days, real conditions include days with both high and low incident radiation and two di?erent PCMs. Predicted temperature of glass cover, absorber plate, water outlet and PCM are obtained with a maximum error of 4.62%. The model was employed to analyze the collector thermal performance. Temperatures, heat transfer, stored energy of collector main components and liquid fraction of PCM are estimated and analyzed in two cases: under clear sky condition without strong changes of solar radiation and under scattered weather with solar radiation variation. Two PCMs with di?erent melting points (45 °C and 60 °C) are analyzed and compared with results without PCM by using the model to evaluate their performance.
关键词： Flat plate solar collector,Thermal energy storage,Thermal model,Experimental validation,PCM
更新于2025-09-10 09:29:36