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A year-round study of a photovoltaic thermal system integrated with phase change material in Shanghai using transient model
摘要： In the study, the daily and monthly performance of a photovoltaic thermal system integrated with phase change material is investigated in Shanghai, China. A three-dimensional model of photovoltaic thermal system integrated with phase change material system is developed and numerically simulated. Water is considered as working fluid, and the fluid flow regime is laminar and incompressible. Both quasi-steady and transient models are compared together, and the transient model is selected because of its higher accuracy. Validation analysis is performed on the numerical model to show the reasonable agreement of current research compared to some other research. After obtaining the suitable operating time for the system, the performance of the system is studied from both energy and exergy viewpoints during the year. An environmental analysis is also conducted to show the annul carbon dioxide mitigation potential. The results show that July is the best month for operating of the system in shanghai with an operating time period of 13.5 h per day on average, while November, December, and January have the lowest operating time period. The percentage of melted phase change material in January, February, March, November and December is zero which means that the melting process does not occur in these months, due to the low ambient temperature and incident solar radiation in Shanghai. Though the overall energy efficiency of the system is higher in summer, the overall exergy efficiency is lower in this season.
关键词： Quasi-steady and transient models,Environmental analysis,Daily and monthly analysis,Energy and exergy analysis,PVT systems
更新于2025-09-23 15:21:01
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Energy and exergy efficiencies enhancement analysis of integrated photovoltaic-based energy systems
摘要： Integrated energy systems (IESs) take advantage of the complementarity of their subsystems to improve the overall system functionality, sustainability and performance. Presently, the cost of the recovery of thermodynamic losses from photovoltaic modules has not been addressed. In this study, novel energy and exergy efficiencies enhancement analysis (EEEEA) is proposed for the study of the implications of recovering the conversion and usage losses from a photovoltaic (PV) module. Four evolutionary IES were analysed: a PV-Battery (System 1); a Photovoltaic-thermal (PV/T)-Battery (System 2); a PV-Battery-Electrolyser-Fuel cell (System 3) and a PV/T-Battery-Electrolyser-Fuel cell (System 4). Actual solar radiation and temperature data coupled with synthesised data were applied. Results show that both the energy and exergy efficiencies of System 2 upgraded by 27.89% and 5.42%, respectively, over System 1. The energy and exergy efficiencies of System 3 degraded by 3.11% and 4.10%, respectively, over System 1; whereas the energy and exergy efficiencies of System 4 degraded by 21.92% and 7.72%, respectively, over System 2. Furthermore, the thermodynamic efficiencies of the IESs did not naturally upgrade with system complexity. The EEEEA can help scientists, engineers and policymakers to analyse IESs with a parent-offspring relationship in order to establish the optimum efficiency and thermo-economics.
关键词： Photovoltaics,Integrated energy systems,Energy and exergy analysis,Exergy centred design,Distributed systems
更新于2025-09-12 10:27:22
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Three-dimensional numerical investigation of a hybrid low concentrated photovoltaic/thermal system
摘要： Concentrated photovoltaic/thermal hybrid collectors have received ever-increasing attention due to the simultaneous output of electric and thermal energy. For further improvement of concentrated hybrid PV/T systems, a simulation method combining the multiphysics fields is necessary to accurately analyze the optical, thermal, and electric performance. Herein, a three-dimensional numerical study has been conducted on a low concentrated photovoltaic/thermal system utilizing a heat transfer fluid as the cooling medium and a compound parabolic concentrator as the mirror field. A finite volume (FV)-CFD code has been employed to simulate the entire model, where the optical modelling is validated theoretically with the Monte Carlo ray-tracing method. The influences of employing various heatsink designs (U-type and Z-type) and coolants (water, ethylene glycol, and therminol VP-1) are numerically investigated. The economic feasibility of the hybrid PV/T system is also assessed in comparison with the standalone PV-cell. Good compatibility with the empirical data was obtained when the appropriate modelling tunings were applied. It is also shown that, on a typical day, the total energy and exergy efficiencies of the system are up to 57.66% and 7.94%, respectively. The Z-type heatsink decreases the average PV-cell temperature than the U-type design, and also the output power is slightly enhanced.
关键词： Photovoltaic/thermal system,FV-DO radiation method,heat sink,energy and exergy analysis
更新于2025-09-12 10:27:22
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Performance evaluation of a thermoelectric ventilation system driven by the concentrated photovoltaic thermoelectric generators for green building operations
摘要： This paper proposed one novel Thermo-Electric Ventilation (TEV) system driven by the concentrated photovoltaic-thermoelectric generator (CPV-TEG), which could use the electric power converted directly from solar energy by CPV-TEG. The effects of incident solar irradiance, number of thermoelectric generators, and ambient air temperatures on the power output of CPV-TEG have been analytically investigated through energy balance and first law of thermodynamics. Furthermore, input current and number of thermoelectric coolers were sensitively varied to optimize the performance of TEV system respectively in heating and cooling modes. Finally, an integrated theoretical and numerical approach was proposed to match the power output of CPV-TEG with the power input of TEV. Modeling results indicate that the output power from CPV-TEG could satisfy the energy demand of TEV system when the input currents of thermoelectric coolers were no more than 2.5 A and 2.8 A respectively for cooling and heating modes. Minimum energy and exergy efficiencies of the system in winter heating mode were confirmed to be 1.67 and 0.24 respectively, which were far higher than that in summer cooling mode. This research may be helpful for enhancing performance and reducing exergy destruction of thermoelectric ventilation system, simultaneously.
关键词： thermoelectric ventilation system,power matching,energy and exergy analysis,concentrated photovoltaic-thermoelectric generator
更新于2025-09-12 10:27:22