- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Potential of water natural circulation coupled with nano-enhanced PCM for PV module cooling
摘要： This paper introduces a new photovoltaic module passive cooling system that works with natural cooling water circulation. The heat was removed from cooling water by a PCM-based cooling system. A special zig zag geometry of PCM container was considered to increase the heat transfer surface. At the ?rst stage of experiments, a composed oil consisting of 82 wt% coconut oil and 18 wt% sun?ower oil was used as PCM. Then, in order to increase the performance of heat transfer between PCM and cooling water, the composed oil was mixed with Boehmite nanopowder (0.009 (w/w)). The cooling performance of the composed oil and nano - composed oil was assessed by monitoring the temperature and the generated electrical power of the panel at various radiation intensities. The results reveal the reliability of the proposed system for cooling of the PV module without need to any pumping system. Moreover, the results show that using nano - composed PCM is more ef?cient than the plain one. The highest increase in the maximum produced power relative to the reference case were obtained in the presence of nano - composed oil, which were 44.74, 46.63, 48.23% at the radiation intensities of 410,530,690 W/m2, respectively.
关键词： Photovoltaic,PCM,Natural circulation,Passive cooling,Boehmite nanoparticles,Heat transfer
更新于2025-09-11 14:15:04
-
Photovoltaic–thermal (PV/T) technology: a comprehensive review on applications and its advancement
摘要： Over the most recent couple of decades, tremendous consideration is drawn towards photovoltaic–thermal systems because of their advantages over the solar thermal and PV applications. This paper intends to show different electrical and thermal aspects of photovoltaic–thermal systems and the researches in absorber design modification, development, and applications. From the previous review articles, it has been concluded that the heat energy exhausted from the PV module can be further utilized in different ways and helps in achieving better efficiency. Furthermore, the types of photovoltaic–thermal systems such as air collector, water collector, and combi system, coupling with heat pump and their application to buildings are also stated. This paper also discussed certain design aspects like modifications in the flow channel by adding fins, thin metallic sheets, roll-bond absorber, and porous media and the effect of these modifications on the hybrid system’s efficiency. Furthermore, the use of the latest technologies such as nanofluids, thermoelectric generators, and phase-change materials improves the overall system performance. The role of soft-computing techniques is forecasting the impact of various parameters on the photovoltaic–thermal system is also discussed.
关键词： Phase-change materials (PCM),PV/T combi,Thin metallic sheets (TMS),Nanofluids
更新于2025-09-11 14:15:04
-
Write Energy Reduction for PCM via Pumping Efficiency Improvement
摘要： The emerging Phase Change Memory (PCM) is considered to be a promising candidate to replace DRAM as the next generation main memory due to its higher scalability and lower leakage power. However, the high write power consumption has become a major challenge in adopting PCM as main memory. In addition to the fact that writing to PCM cells requires high write current and voltage, current loss in the charge pumps also contributes a large percentage of high power consumption. The pumping efficiency of a PCM chip is a concave function of the write current. Leveraging the characteristics of the concave function, the overall pumping efficiency can be improved if the write current is uniform. In this article, we propose a peak-to-average (PTA) write scheme, which smooths the write current fluctuation by regrouping write units. In particular, we calculate the current requirements for each write unit by their values when they are evicted from the last level cache (LLC). When the write units are waiting in the memory controller, we regroup the write units by LLC-assisted PTA to reach the current-uniform goal. Experimental results show that LLC-assisted PTA achieved 13.4% of overall energy saving compared to the baseline.
关键词： pumping efficiency,write regrouping,Phase change memory (PCM),charge pump
更新于2025-09-10 09:29:36
-
AIP Conference Proceedings [Author(s) SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems - Santiago, Chile (26–29 September 2017)] - Numerical study of a two pass shell and tube latent heat energy storage system
摘要： The thermal behaviour of PCM in different configuration of heat exchangers is analysed for the purpose of design and optimisation of a latent heat thermal energy storage unit. Numerical modelling in conjunction with scale analyses provides a cost effective means to examine the performance of different configurations of latent heat storage systems. The main objective of this work is to scale down an experimental set up to a numerical model which can represent the thermal behaviour of the system with reasonable computational time. A U-tube element from a shell and tube thermal storage experimental set up was used as the model for a numerical study, using FLUENT. The predicted results of the temperature profiles in the PCM domain are in agreement with the measured data. Moreover, the heat transfer fluid outlet temperature and duration of the phase change processes are consistent with experimental results. Using the experimental initial temperature at each point in comparison to using an average initial temperature from all points can improve the predicted temperature profiles. Furthermore, three different mushy zone constants; namely 105, 107, 108 were used to examine the impact on the rate of melting. It was found that the constant 107 provides a closer solution to the experimental results. Results of this study show that the small scale model can represent the lab scale set up, providing more detail about the thermal behaviour of the PCM which is difficult to capture by measurement. The model can also be used for further examination of a high temperature PCM within the same set up for a CSP application.
关键词： FLUENT,shell and tube,numerical modelling,PCM,latent heat thermal energy storage
更新于2025-09-10 09:29:36
-
Energy performance analysis of a novel solar PVT loop heat pipe employing a microchannel heat pipe evaporator and a PCM triple heat exchanger
摘要： This study presents a numerical analysis of the energy efficiency for a novel solar PVT Loop Heat Pipe (PVT-LHP) employing a novel Micro-channel evaporator and a novel PCM heat storage exchanger. It presents a description of the different sub-models in the PVT-LHP system (the PVT model, the microchannel heat collector model and the novel PCM triple heat exchanger model) and the integrated model of the system. The integrated model of the system was solved by ensuring a heat balance at the condenser and the evaporator. A parametric analysis has been performed in order to assess the influence of the environmental parameters (i.e. solar radiation, air temperature, wind velocity), structural parameters (i.e. glazing cover, the number of absorbing microchannel heat pipes, PV cell packing factor), the circulating fluid variables (i.e. cold-water inlet temperature and water mass flow rate) on the energy performance of the system. The novel PVT-LHP has been compared with a conventional Solar PVT-LHP system. It was found that lower solar radiation, lower ambient air temperature, higher wind speed, higher packing factor, lower cold-water inlet temperature and a smaller cover number led to an enhanced electrical efficiency, but a reduced thermal efficiency of the module; whereas a higher cold-water mass flow rate and a greater number of microchannel heat pipes gave rise to both thermal and electrical efficiencies of the module. It was also found that an increase of solar radiation, ambient temperature, cover number, microchannel heat pipe number and packing factor are favourable factors for the overall COP (Coefficient Of Performance) of the system, whereas an increase of wind velocity and cold water mass flow rate are unfavourable. The study indicated the existence of an optimal cover number, number of microchannel heat pipes and mass flowrate. Under the given design conditions, the electrical, thermal and overall efficiency of the PV/LHP module were 12.2 %, 55.6 % and 67.8% respectively and the novel system can achieve 28% higher overall energy efficiency and 2.2 times higher COP compared to a conventional system. The integrated computer model developed in this study can be used to design and optimize the novel PVT-LHP heating system.
关键词： microchannel,power supply,PVT,Loop Heat Pipe,PCM triple heat exchanger,heating
更新于2025-09-10 09:29:36
-
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
-
AIP Conference Proceedings [Author(s) SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems - Santiago, Chile (26–29 September 2017)] - System-level simulation of a novel solar power tower plant based on a sodium receiver, PCM storage and sCO2 power block
摘要： In this work, we explore for the first time the viability and the annual performance of a solar plant which combines a sodium receiver, phase-change material (PCM) storage and supercritical CO2 (sCO2) power block. The simulation results suggest that the system is thermodynamically and economically viable, reducing the levelized cost of electricity (LCOE) compared with a conventional CST plant based on molten salts. The paper presents a new dynamic model of the novel plant configuration which is used for performing a storage sizing study obtaining the best plant investment.
关键词： sCO2 power block,solar power tower,LCOE,PCM storage,sodium receiver
更新于2025-09-09 09:28:46
-
RCS Reduction and Gain Enhancement for the Circularly Polarized Array by Polarization Conversion Metasurface Coating
摘要： High-gain, the ultra-wide band circularly polarized (CP) array with low radar cross section (RCS) is proposed based on (UWB) polarization conversion metasurface (PCM) coating. A chessboard-like coating is formed by a mess of arrow-shaped PCM elements which have UWB and high polarization conversion ratio. The coating is distributed beneath the dipoles and behaving as a reflector. With the PCM beneath each dipole, the CP radiation is achieved and enhanced in a low profile by the radiating wave and the reflected wave, which have equal amplitude and 90° phase difference. With the chessboard-like coating, the incident wave is converted into the equal amplitude and out-of-phase reflected waves, which will cancel each other to reduce the backward scattering. The performances of the array are validated by both simulations and measurements. The results show that the left-hand CP radiation is achieved in 11.25 GHz to 12.31 GHz with the RCS being reduced for more than 4.8 dB in 10.5 GHz to 35.1 GHz.
关键词： high gain,circular polarization,low profile,radar cross section (RCS),polarization conversion metasurface (PCM)
更新于2025-09-09 09:28:46
-
Unraveling the Role of Π - Conjugation in Thiophene Oligomers for Optoelectronic Properties by DFT/TDDFT Approach
摘要： Thiophene oligomer has been investigated using DFT/TDDFT calculations with an aim to check its suitability for opto electronic applications and also to analyse the influence of π-bridge. Our results revealed that thiophene oligomers have excellent π-conjugation throughout. FMO analysis give an estimate of band gap of thiophene oligomer and further revealed HOMO are localized on π – bridge, donor group and LUMO are localized on π – bridge and acceptor group. A TDDFT calculation has been performed to understand the absorption properties of them in gas phase and solvent phase. PCM calculations convey that absorption maxima show positive solvatochromism. Among the designed candidates, the one with more π – bridge show higher wavelength of absorption maxima and would be a choice for better optoelectronic materials. NBO analysis provides support for complete delocalization in these systems. It is interesting to note that oligomer with more π–bridge display an enhanced optoelectronic properties than with less π – bridge.
关键词： Thiophene oligomer,TDDFT,π – bridge,PCM,NBO
更新于2025-09-09 09:28:46
-
[IEEE 2018 48th European Microwave Conference (EuMC) - Madrid, Spain (2018.9.23-2018.9.27)] 2018 48th European Microwave Conference (EuMC) - Characterization of Phase Change Material Germanium Telluride for RF Switches
摘要： This paper presents the simulation and measured results of a phase-change material (PCM) based radio-frequency (RF) switch optimized to improve the ratio between OFF-state and ON-state resistivity. Various samples having germanium telluride (GeTe) films are developed and imaged using Atomic Force Microscope (AFM) and are compared with cross-wafer resistance measurement results to determine the optimum sputtering conditions of the GeTe films. A simple four-layer fabrication process for GeTe based switches is presented. Several switches with different micro-heater dimensions are compared to investigate the performance of heater and its impact on the isolation performance of switch. A compact RF series switch has been measured, demonstrating an insertion loss of only 0.29 dB and an OFF-state isolation better than 23 dB over DC–26 GHz frequency range, yielding a relatively high Roff/Ron ratio.
关键词： SPST,Latching RF Switches,Phase Change Material (PCM),RF Switch,Germanium Telluride (GeTe)
更新于2025-09-04 15:30:14