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Comparison of mixed-mode forced-convection solar dryer with and without stainless wire mesh in solar collector

Clean Energy 2023年第6期7卷 1316-1329页

作者： Siwakorn Srithanyakorn Sungwan Bunchan Bundit Krittacom Ratinun Luampon Department of Mechanical Engineering Faculty of Engineering and TechnologyRajamangala University of Technology Isan744Suranarai RdNai mueangMueangNakhon Ratchasima30000Thailand Development in Technology of Porous Materials Research Laboratory:DiTo-Lab Thailand

A mixed-mode forced-convection solar dryer(MMFCSD)is a device that utilizes both direct and indirect solar energy.The solar col-lector,which stores thermal energy for indirect solar uses,is an essential component of the dryer.Unfortunately,the thermal effi-ciency of this device is generally low.In this study,a technique was employed to improve the heat transfer of the solar collector in a MMFCSD.The technique involved adjusting the air flow pattern into a swirling flow to disturb the thermal boundary layer on the absorber plate under forced convection by using stainless wire mesh.The experiment was conducted under actual conditions and bananas were used as the drying sample.The experimental results of the thermal efficiency of the solar collector(ƞ_(solar))and the drying efficiency(ƞ_(drying))are presented.The results indicated that the air outlet temperature andƞsolar of the solar collector with stainless wire mesh were higher than the case without stainless wire mesh,reaching a maximum temperature of 46.22°C and 37.97°C,and average ƞ_(solar) of 0.26±0.02 and 0.14±0.01,respectively.The MMFCSD with stainless wire mesh had a higher ƞ_(drying) than the case without stain-less wire mesh,with values of 0.048±0.004 and 0.039±0.003,respectively,resulting in an~23.07%increase.This was attributed to the air swirling flow through the stainless wire mesh and the heat accumulation in the drying chamber,which led to an increase in the drying chamber temperature from 54.03°C to 63.60°C,an increase in the effective moisture diffusivity from 7.28×10^(-7) to 1.19×10^(-6) m^(2)/s and a decrease in the drying time of 5 h 30 min.However,further research is needed to investigate the quality of the dried sam-ples and their economic value.

关键词： mixed-mode solar drying direct solar drying indirect solar drying stainless wire mesh drying efficiency solar collector

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Study on carnauba wax as phase-change material integrated in evacuated-tube collector for solar-thermal heat production

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Clean Energy 2023年第3期7卷 547-554页

作者： Ruben Bartali MicheleBolognese NicolaFronza LucaPrattico AlbertoZanetti TiagoOsorio Luigi Crema Fondazione Bruno Kessler Centre on Sustainable EnergyVia Sommarive 1838123 TrentoItaly University ofÉvora-Renewable Energies Chair Palácio VimiosoLargo Marquês de Marialva7002-554ÉvoraPortugal

The evacuated-tube collector(ETC)for solar heat production is one of the most efficient systems to convert Sun energy into usable energy.Unfortunately,some technological barriers are still present in solar-thermal heat systems that limit the use of these technologies to decarbonize processes.An important obstacle is the requirement for heat at stable temperatures,which is not always achievable by solar fields,e.***.variable sky.For that reason,in this work,we studied the phase-change materials embedded in the ETC to keep stable the water temperature for a short period(minutes,hours).In this study,carnauba wax was used as a sustainable phase-change material(PCM),to avoid the use of PCM based on hydrocarbon waxes.The PCM has been packaged using a polyethylene bag inserted into an ETC with heat-pipe technologies and tested.The collector has been tested outdoors under solar irradiation and under shading conditions.The experimental results show that is possible to detect a sensible effect of the PCM on the temperature using 4 kg of carnauba wax while there is an important effect on the temperature stabilization using 9 kg of PCM.Using 9 kg of the PCM,we observed a stability of the outlet water temperature at 65°C for 30 minutes under shading conditions.

关键词： energy storage carnauba wax ETC solar collector solar heat PCM

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Heat Leakage Numerical Investigation of a Compound Parabolic ConcentratorPulsating Heat Pipe solar collector

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Journal of Thermal Science 2022年第5期31卷 1318-1326页

作者： XU Rongji CHEN Jingyan ZHANG Xiaohui WANG Ruixiang XU Shuhui Beijing Engineering Research Center of Sustainable Energy and Buildings Beijing University of Civil Engineering and ArchitectureBeijing100044China

As a new type of equipment for solar medium temperature utilization, the compound parabolic concentrator-pulsating heat pipe solar collector(CPC-PHPSC) uses pulsating heat pipe(PHP) as an endotherm, which can realize efficient energy conversion. The design of proper concentration ratio of compound parabolic concentrator(CPC) ensures that the incident sunlight can be concentrated on the evaporator section surface of PHP without solar tracking system. The objective of the present work is to study the influence of solar radiation intensity, air speed, material thickness(glass and insulation board) and tilt angle on the thermal performance of the new collector, which is difficult to control in the experiment. The heat leakage process and characteristics of the CPC-PHPSC were numerically studied by establishing a 3D numerical model of the collector unit. The results show that the theoretical collector efficiency of CPC-PHPSC reaches 74.5%, which is consistent with the experimental results. During operation, the heat collection performance is the best when the tilt angle is 45° and the solar radiation intensity is 1000 W/m^(2), while the excessive air speed will increase the convective heat loss. Increasing the thickness of insulation board and glass has little effect on the collector efficiency.

关键词： solar collector CPC(Compound Parabolic Concentrator) pulsating heat pipe solar irradiation intensity glass thickness

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Efficiency enhancement of building multi-layer solar collector with SiO2–TiO2 hybrid nanofluids

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Building Simulation 2023年第10期16卷 1851-1862页

作者： N.N.M.Zawawi W.H.Azmi Z.A.A.Majid R.A.Rahim H.M.Ali Lebuhraya Tun Razak Centre for Research in Advanced Fluid and Processes26300GambangKuantanPahangMalaysia Faculty of Mechanical and Automotive Engineering Technology Universiti Malaysia PahangPekanPahang26600Malaysia Kulliyyah of Allied Health Sciences International Islamic University of MalaysiaBandar Indera Mahkota25200KuantanPahangMalaysia ECE Department Kulliyyah of EngineeringInternational Islamic University MalaysiaJalan GombakKuala LumpurMalaysia Mechanical Engineering Department King Fahd University of Petroleum and MineralsDhahran31261Saudi Arabia Interdisciplinary Research Center for Renewable Energy and Power Systems(IRC-REPS) King Fahd University of Petroleum and MineralsDhahran31261Saudi Arabia

Due to the depletion of conventional energy sources and its limitless resources,solar energy is currently being considered as a viable alternative,especially for water heating systems.The thermal performance of multilayer solar collectors for water heating systems can be improved further by introducing hybrid nanofluids as advanced fluids.This study demonstrates the utilisation of hybrid nanofluids in heating systems by employing a multilayer absorber solar collector.The SiO2–TiO2 hybrid nanofluids at volume concentrations up to 2.0%were tested at various flow rates(1.7 to 3.7 LPM)and solar radiation intensities(250 to 1000 W/m2).The thermal performance of the solar collector was assessed by measuring the temperature variation,heat loss,and overall efficiency of the collector.At the optimal volume concentration,the temperature difference for solar collectors employing SiO2–TiO2 hybrid nanofluids increased significantly.The optimal volume concentration of 1.5%yields a maximum temperature difference of 9.5°C.In addition,the efficiency and fluid temperature of the solar collector containing hybrid nanofluids have been enhanced by 22%and 37%,respectively.The SiO2–TiO2 hybrid nanofluids with the optimal volume concentration of 1.5%were therefore recommended for maximum efficiency in the solar collector.

关键词： solar collector hybrid nanofluids solar water heating system solar simulator thermal efficiency

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A portable,auxiliary photovoltaic power system for electric vehicles based on a foldable scissors mechanism

Energy and Built Environment

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Energy and Built Environment 2024年第1期5卷 81-96页

作者： Zhou Jin Dongyang Li Daning Hao Zutao Zhang Liang Guo Xiaoping Wu Yanping Yuan China Railway Wuhan Electrification Bureau Group Shanghai Electric Co. LtdShanghai 201799PR China School of Mechanical Engineering Southwest Jiaotong UniversityChengdu 610031PR China

In recent years,countries worldwide have actively advocated electric vehicles for environmental protection.How-ever,restrictions on the driving range and charging have hampered the promotion of electric vehicles.This study proposes a portable,auxiliary photovoltaic power system based on a foldable scissors mechanism for electric vehicles.The system includes a photovoltaic power generation module and an electricity transfer module.The photovoltaic power generation module built based on a foldable scissors mechanism is five times smaller than in its unfolded state,improving its portability in its folded state.The electricity transfer module transfers electricity into the cabin via wireless power transfer units and stores electricity in supercapacitors.solar simulation exper-iments were conducted to evaluate the system’s performance:maximum output power of 1.736 W is measured when the load is 5Ω,while maximum wireless power transfer efficiency is up to 57.7% with 10Ω load.An elec-tric vehicle in Chengdu city was simulated for a case study.The results show that the annual output of a single photovoltaic power system can drive the MINIEV for 423.625 km,indicating that the proposed system would be able to supply power for electric vehicles as an auxiliary power supply system.

关键词： Auxiliary photovoltaic power system Energy harvesting Scissors mechanism solar collector Electric vehicle

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Experimental Study of the Temperature Distribution of solar collector Pavement

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武汉理工大学学报 2010年第17期32卷 227-230页

作者： ZHANG J Z WU S P CHEN M Y Key Laboratory of Silicate Materials Science and Engineering Wuhan University of TechnologyWuhan 430070China

Black asphalt road have excellent properties to collect the solar radiation and good use of asphalt absorb solar energy is a new energy technology. Asphalt is a sticky plastic material,its modulus and strength will change with temperature and the actual bearing capacity of pavement structure will change as well. A new method was used to evaluate the temperature change of asphalt pavement. By simulate solar radiation on asphalt sample to study the change of the temperature field. The temperature distribution of the asphalt concrete under the same light radiation and circulating water was also studied. The results indicate that this method can be a good simulation of solar collectors on the surface temperature field.

关键词： temperature field asphalt sample solar collector fluorescent lamp analog

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An Application of Nonlinear Autoregressive(NARX)Model to Predict Adsorbent Bed Temperature of solar Adsorption Refrigeration System

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Journal of Systems Science and Systems Engineering 2023年第6期32卷 687-707页

作者： Fatih Bouzeffour Benyoucef Khelidj Unitéde Développement des Equipements Solaires UDES Centre de Développement des Energies Renouvelables CDER42415TipazaAlgeria FIMA University Djilali Bounaama of Khemis-Miliana44225Khemis-MilianaAlgeria

In any solar adsorption refrigeration system,there are three major components:a solar collector adsorbent bed,a condenser and an evaporator.All of those components operate at different temperature levels.A solar collector with a tubular adsorbent configuration is proposed and numerically investigated.In this study,a nonlinear auto-regressive model with exogenous input is applied for the prediction of adsorbent bed temperature during the heating and desorption period.The developed neuronal model uses the MATLAB Network toolbox to obtain a better configuration network,applying multilayer feed-forward,the TANSIG transfer function,and the back-propagation learning algorithm.The input parameters are ambient temperature and the uncontrolled natural factor of solar radiation.The output network contains a variable representing the adsorbent bed temperature.The values obtained from the network model were compared with the experimental data,and the prediction performance of the network model was examined using various performance parameters.The mean square error(MSE)and the statistical coefficient of determination(R2)values are excellent numerical criteria for evaluating the performance of a prediction tool.A well-trained neural network model produces small MSE and higher R2 values.In the current study,the adsorbent bed temperature results obtained from a neural network with a two neuron in hidden layer and the number of the tapped time-delays d=9 provided a reasonable degree of accuracy:MSE=1.0121 and R2=0.99864 and the index of agreement was 0.9988.This network model,based on a high-performance algorithm,provided reliable and high-precision results concerning the predictable temperature of the adsorbent bed.

关键词： Artificial neural networks NARX solar collector adsorption refrigerator adsorbent bed temperature

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Parabolic Trough collector and Central Receiver Coupled with Fresnel Lens:Experimental Tests

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International Journal of Automation and computing 2020年第4期17卷 572-587页

作者： Angelica Palacios Dario Amaya Olga Ramos Universidad Militar Nueva Granada Bogota 110121Colombia

Renewable energies have a high impact on power energy production and reduction of environmental pollution worldwide,so high efforts have been made to improve renewable technologies and research about them.This paper presents the thermal performance results obtained by simulation and experimental tests of a parabolic trough collector with central receiver coupled to Fresnel lens,under different configurations on the pipe.The simulation method was computational fluid dynamics(CFD)analysis in SolidWorks(R)soft-ware tool,which works with Naiver-Stokes equations to converge on a solution.Experimental tests were formed with all configurations proposed and three observations for each one,a total of 12 observations were performed in all research.As a result,the best thermal performance in simulation was achieved with the Fresnel lens and black pipe collector,with a maximum temperature of 116℃under 1000 W/m^2 radiation,the same system achieved in experimental tests a maximum temperature of 96℃with a radiation of 983 W/m^2.

关键词： solar collector parabolic trough collector Fresnel lens thermal conductivity solar power

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Receiver tube heat transfer analysis of a CCP collector designed based on branched fractals geometry

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International Journal of Agricultural and Biological Engineering 2020年第5期13卷 56-62页

作者： Angélica Palacios Darío Amaya Olga Ramos GAV Research Group Universidad Militar Nueva GranadaBogota 110111Colombia

For the development of systems related to renewable energy and specifically for thermo-solar energy,it is essential to study and analyze the different thermal phenomena of heat transfer,in search of the best conditions that allow strengthening the designs.Phenomena such as radiation,convection,and conduction are highly studied,from the field of materials to the field of infrastructure,finding day to day optimal solutions that guarantee a great use of the solar resource available on the earth's surface.This study presented the results of heat transfer analysis on a receiver pipe in a CCP;designed using the theory of branched fractal geometry to improve the heat transfer associated with concentrating solar capture systems.A fractal structure as a branch or arboreal fractal type network,influenced thermal and electrical parameters,as electrical resistance,thermal resistance,and convective heat transfer,so increasing the level branch heat transfer can be enhancement along of the pipe.The use of renewable energies in agriculture benefits the industrial processes that require a continuous power system,due to climatic conditions and geographical location is not a guarantee in food production fields,which reason solar capture systems contribute to food dehydration processes,water heating,refrigeration,and energy production.

关键词： heat transfer fractal geometry solar collector fractality fractal dimension parabolic cylindrical concentrator

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An Energy Production System Powered by solar Heat with Biogas Dry Reforming Reactor and Solid Oxide Fuel Cell

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Smart Grid and Renewable Energy 2023年第5期14卷 85-106页

作者： Akira Nishimura Ryotaro Sato Eric Hu Division of Mechanical Engineering Graduate School of Engineering Mie University Tsu Japan School of Electrical Mechanical Engineering The University of Adelaide Adelaide Australia

In this paper, an energy system consisting of solar collector, biogas dry reforming reactor and solid oxide fuel cell (SOFC) has been proposed. The heat produced from the concentrating solar collector is used to drive a biogas dry reforming reactor in order to produce H2 as a fuel for SOFC, in such as system. The aim of this study is to clarify the impact of climate data on the performance of solar collector with various sizes/designs. The temperature of heat transfer fluid produced by the solar collector is calculated by adopting the climate data for Nagoya city in Japan in 2021. The amount of H2 produced from the biogas dry reforming reactor and the power generated by SOFC were simulated. The results show the temperature of heat transfer fluid (Tfb) and Tfb ratio (a) based on the length of absorber (dx) = 1 m have a peak near the noon following the trend of solar intensity (I). Results also revealed that a increases with increase in dx. It is found that the differences of Tfb and a between dx = 2 m and dx = 3 m are larger than those between dx = 1 m and dx = 2 m. It is revealed that Tfb and a are higher in spring and summer. dx = 4 m is the optimum length of solar absorber. The amount of H2 produced from the biogas dry reforming reactor as well as the power generated by SOFC is the highest in August, resulting that it is prefer to produce H2 and to generate SOFC in summer.

关键词： solar collector Fluid Temperature Climate Data Biogas Dry Reforming H2 Production SOFC

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