Multi-Objective Optimization of Hybrid Renewable Tri-Generation System Performance for Buildings

Hybrid renewable energy systems are subject to extensive research around the world and different designs have found their way to the market and have been commercialized. These systems usually employ multiple components, both renewable and conventional, combined in a way to increase the system’s overall efficiency and resilience and to lower GHG emissions. In this paper, a hybrid renewable energy system was designed for residential use and its annual energy performance was investigated and optimized. The multi-module hybrid system consists of a Ground-Air Heat Exchanger (GAHX), Photovoltaic Thermal (PVT) panels and Air to Water Heat Pump (AWHP). The developed system’s annual performance was simulated in the TRaNsient SYStem (TRNSYS) environment and optimized using the General Algebraic Modelling System (GAMS) platform. Multi-objective non-linear optimization algorithms were developed and applied to define optimal system design and performance parameters while reducing cost and GHG emissions. The results revealed that the designed system was able to satisfy building thermal heating/cooling loads throughout the year. The ground source heat exchanger contributed 21.3% and 26.3% of the energy during heating and cooling seasons, respectively. The initial design was optimized in terms of key performance parameters and module sizes. The annual simulation analysis showed that the system was able to self-generate and meet nearly 29.4% of the total HVAC electricity needs, with the rest being supplied by the grid. The annual system module performance efficiencies were 13.4% for the PVT electric and 5.5% for the PVT thermal, with an AWHP COP of 4.0.

The Impact of a Paraelectric layer in the FE/DE Stack on Performance of NCFET

<div>In this letter, through TCAD simulations, we show that the introduction of a thin paraelectric (PE) layer between the ferroelectric (FE) and dielectric (DE) layers in an MFIS structure, expands the design space for the FE layer enabling hysteresis-free and steep subthreshold behavior, even with a thicker FE layer. This can be explained by analyzing the FE-PE stack from a capacitance perspective where the thickness of the PE layer in the FE-PE stack has the effect of reducing the FE layer thickness, while also reducing the remnant polarization. Finally, for the same FE-PE-DE stack, analog performance parameters such as $\frac{g_{m}} g_{ds}}$ and $\frac{g_{m}}{I_{d}}$ are analyzed, showing good characteristics over a wide range of gate lengths, at low drain voltages, thus demonstrating applicability for low power applications.</div>

The Impact of a Paraelectric layer in the FE/DE Stack on Performance of NCFET

<div>In this letter, through TCAD simulations, we show that the introduction of a thin paraelectric (PE) layer between the ferroelectric (FE) and dielectric (DE) layers in an MFIS structure, expands the design space for the FE layer enabling hysteresis-free and steep subthreshold behavior, even with a thicker FE layer. This can be explained by analyzing the FE-PE stack from a capacitance perspective where the thickness of the PE layer in the FE-PE stack has the effect of reducing the FE layer thickness, while also reducing the remnant polarization. Finally, for the same FE-PE-DE stack, analog performance parameters such as $\frac{g_{m}} g_{ds}}$ and $\frac{g_{m}}{I_{d}}$ are analyzed, showing good characteristics over a wide range of gate lengths, at low drain voltages, thus demonstrating applicability for low power applications.</div>

Temperature Sensitivity Analysis of Dual Material Stack Gate Oxide Source Dielectric Pocket TFET

Temperature dependence performance variation is one of the major concerns in predicting the actual electrical characteristics of the device as the bandgap of semiconducting material varies with temperature. Therefore, in this article, for the first time, the impact of temperature variations ranging from 300K to 450K on the DC, analog/ radio frequency, and linearity performance of dual material stack gate oxide-source dielectric pocket-tunnel- field-effect transistor (DMSGO-SDP-TFET) is investigated. In this regard, technology computer-aided design (TCAD) simulator is used to analyze DC, and analog/radio frequency performance parameters such as carrier concentration, energy band variation, band to band tunneling rate, IDS - VGS characteristics, transconductance (gm), cut o frequency (f T ),gain-bandwidth product (GBP), maximum oscillating frequency (fmax), transconductance frequency product (TFP), and transit time considering the impact of temperature variations. Furthermore, linearity parameters such as third-order transconductance (gm3), third-order voltage intercept point (VIP3), third-order input-interception point (IIP3), and intermodulation distortion (IMD3) are also analyzed with temperature variations as these performance parameters are significant for linear and analog/radio frequency applications. Moreover, the performance of the proposed DMSGO- SDP-TFET is compared with the conventional dual-material stack gate oxide-tunnel- field-effect transistor (DMSGO-TFET). From the comparative analysis, in terms of % per kelvin, DMSGO-SDP-TFET demonstrates lesser sensitivity towards temperature variation. Hence, the proposed DMSGO-SDP-TFET can be a suitable candidate for low power switching and analog/radio frequency applications at elevated temperatures as compared to conventional DMSGO-TFET.

Design of compressor impeller under high Reynolds number conditions

Purpose A parametric method for designing the hub, casing and blades of the miniature centrifugal compressor impeller was developed. The relationship model of the size, aerodynamic and performance parameters of the centrifugal impeller was established. Based on the selected design parameters, the miniature centrifugal-type impeller was designed, and the work efficiency was calculated. Design/methodology/approach In this study, a micro-centrifugal compressor impeller with a diameter of less than 25 mm was designed. A parametric design method was developed, and the functional relationship between the geometric and gas fluidity parameters was established. Findings The results of this study showed that the performance parameters of the designed micro-centrifugal impeller satisfied the design requirements. The proposed method is useful as a reference for designing and analysing compressor impellers under high Reynolds number conditions. Originality/value A parametric design method was developed, and the functional relationship between the geometric and gas fluidity parameters was established. Under the Reynolds number conditions, the flow characteristics of the gas in the compressor were analysed; the shear-stress transport turbulence equation was solved using the finite volume method. In addition, the effects of the Reynolds number on the velocity, pressure, mass flow and efficiency of the micro-scale centrifugal compressor were evaluated. The results showed that the performance parameters of the designed micro-centrifugal impeller satisfied the design requirements. The proposed method is useful as a reference for designing and analysing compressor impellers under high Reynolds number conditions.

Performance reliability analysis of multi-state degraded system with improved Lz transform

Universal Generating Functions and Lz transformations have been widely used in the reliability modeling of multi-state systems. In order to solve the problem of complex calculations due to the dense random combination of multi-state performance parameters in the Lz transformation, a screening function is defined before the Lz transformation, and the screening function is combined with the performance threshold to screening the state performance parameters in advance, and the process is simplified through the screen matrix and the screen block diagram, effectively reduce the combined dimensions and quantity, improve the efficiency of reliability analysis, and combine with specific examples for application verification.

Statistical analysis of properties of non-fullerene acceptors for organic photovoltaics

From ~1500 published journal papers on organic photovoltaics (OPVs), we extracted OPV performance parameters of power conversion efficiency (PCE), open circuit voltage (VOC) and short circuit current density (JSC) and chemical structures of photovoltaic layer materials to investigate the relation between the extracted data of OPVs accompanied by non-fullerene acceptors (NFAs). Our analysis indicated that there was a suitable range of VOC for high PCE or JSC in NFAs. We also investigated the correlation between the performance parameters and chemical structures of small molecule NFAs. Our approach may enable us to provide new design strategy for high performance OPVs.

Prediction and investigation between impeller blade shape parameters and performance parameters in CFD and ANN

The blade shape parameters have a remarkable effect on the centrifugal pump performance. In order to reveal the relationship between these parameters and pump performance, a single channel was regarded as the research object to calculate its performance by numerical simulation, and the performance was measured on an experimental rig. The optimized ANN is proposed, and it is proved to be highly accurate. The ANN correlation coefficient of the total response could be above 0.997 after thousands of retaining. The sorts and degrees affecting performance parameters were found out by gray relation analysis. It was found that the blade angles at the leading edge were more influential for reaction force, head and minimum pressure, while the wrap angles had greater impact for efficiency. Furthermore, a multiple linear regression model was established to quantify the weight and trend of the influence of blade shape parameters on performance. The results provide a reference guide for the optimized design of centrifugal impeller to improve pump performance.