Improvement Of Total Efficiency Research Articles

An integrated machine learning and metaheuristic approach for advanced packed bed latent heat storage system design and optimization

To tackle the challenge of waste heat recovery in the industrial sector, this research presents a novel design and optimization framework for Packed Bed Latent Heat Storage Systems (PBLHS). This features a Deep Learning (DL) model, integrated with metaheuristic algorithms. The DL model was developed to predict PBLHS performance, trained using data generated from a validated Computational Fluid Dynamics (CFD) model. The model exhibited a high performance with an R2 value of 0.975 and a low Mean Absolute Percentage Error (<9.14%). To enhance the ML model's efficiency and optimized performance, various metaheuristic algorithms were explored. The Harmony Search algorithm emerged as the most effective through an early screening and underwent further refinement. The optimized algorithm demonstrated its capability by rapidly producing designs that showcased an improvement in total efficiency of up to 85% over available optimized experimental PBLHS designs. This research underscores the potential of ML-integrated approaches in laying the groundwork for generalized design frameworks for TES systems, offering efficient and effective solutions for waste heat recovery.

IMPROVING THERMAL AND ELECTRICITY GENERATION PERFORMANCE OF PHOTOVOLTAIC/THERMAL (PV/T) SYSTEMS USING HYBRID NANOFLUID

Solar energy is a safe and clean source of energy, available on the Earth throughout the year. A photovoltaic/thermal (PV/T) system is a device designed to take solar energy and convert it into electrical/thermal energy. Photovoltaic/ thermal systems can also be useful to produce hot fluid (usually water) along with the generation of electrical energy. In addition, the electric generating performance of PVs increases with heat discharging ability of thermal system, which also prevents overheating in PV systems. Nanofluid is a new generation heat transfer fluid that delivers higher thermal conductivity and heat transfer rate compared to conventional fluids. The thermal conductivity of the nanofluid depends on the size of the nanoparticles, concentration of the nanofluid, and the method of its preparation. In this study, it is aimed to increase the thermal heat transfer of the PV/T system by using hybrid nanofluids, manufactured by adding 0.5&amp;#37; Fe&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; and Fe&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt; nanoparticles to the water as a working fluid. By using hybrid nanofluids, increase in bidirectional performance along with enhanced cooling is achieved. In the experimental study, more heat was withdrawn from the heated PV panels by utilizing the high thermal conductivity of the hybrid nanofluid, and the best improvement in total efficiency was obtained as 86&amp;#37; for the hybrid nanofluid. With the use of hybrid nanofluids in the cooling circuit, the electrical and thermal efficiency of the PV panel has reached to overall 81&amp;#37; on average basis.

The influence of splitter blades and meridional profiles on the performance of small-scale turbopumps for ORC applications; analysis, neural network modeling and optimization

This work presents the influence of splitters on the performance of small-scale turbopumps for organic Rankine cycle applications numerically. Different design parameters, such as impeller diameter at the outlet, number of blades, blade angle at the trailing edge, and the length and location of the splitter blades, are studied for both shrouded and unshrouded impellers at tip clearance ratios of 0.05 and 0.10 (relative to blade height). The results suggest that splitter blades can increase impeller head coefficient and slip factors up to 10%–24% depending on the blade outlet angle. At the same time, the total efficiency is not influenced significantly. The CFD calculations predict that the placement of splitters in the middle of the blade channel leads to the maximum head coefficient for shrouded impellers. In contrast, for the tip clearance ratio of 0.10, a higher head coefficient is observed for placement closer to the suction side of the main blade. After that, different meridional profiles are studied to investigate their influence on the performance characteristics and mitigation of tip clearance effects. Profiles with a sharper change of cross-section area at the inlet rather than a linear change are found more advantageous, as higher head rise, total efficiency, and static efficiency are observed. In the end, the splitter blade profiles are optimized through techniques of design of experiments, leading to a 2.43% improvement in total efficiency. In contrast, the head rise remains constant, and static efficiency decreases by 0.49% for an impeller with a tip clearance ratio of 0.05.

Design of a Composite Decoupling Structure for Dual-Band Dual-Polarized Base Station Array

A composite decoupling structure is proposed to ameliorate the mutual couplings for dual-band dual-polarized base station array. The structure consists of dual-band decouple surface combined with staggered dielectric surface and several meandered line resonators embedded on the ground. The proposed decoupling structure achieves synchronously reduction of c-pol E-plane, H-plane, and x-pol couplings. In this letter, a staggered 2-1-2 array integrated with the proposed decoupling structure is simulated and measured. The results demonstrate that the decoupled array is operating in the 3.3–3.7 GHz (B1) and 4.8–5.5 GHz (B2) bands with VSWR better than 1.5 and the isolation can be improved to 20 dB in B1 band and 25 dB in B2 band even higher. The radiation patterns of the decoupled array are well maintained with about 20% (B1) and 5% (B2) total efficiency improvement, and the envelope correlation coefficient of the ports is decreased from above 0.02 to less than 0.003 over the whole operating bands. The proposed scheme has potential application prospects in massive multiple-input–multiple-output and fifth-generation (5G) communication systems.

Xiaoke Decoction in treatment of type II diabetes: A Meta-analysis

ObjectiveTo systematically evaluate the clinical effect of Xiaoke Decoction in the treatment of type 2 diabetes. MethodsChinese databases such as CNKI, Wanfang, Weipu Chinese Biomedical Journal Database, and Chinese Medical Biological Literature Database, PubMed, Cochrane Library, Embase, and Web of Science were searched for English language literature from their inception until November 2019. A Meta-analysis was performed using RevMan 5.3 and Stata 12.0. ResultsThirty-eight studies were included in this study, with a total of 3757 patients. It was found that adding Xiaoke Decoction could improve total efficiency. The Xiaoke Decoction groups surpassed the western medicine groups regarding improvement in total efficiency (OR = 3.49; 95% CI: 2.78–4.39, P < 0.00001). Adding Xiaoke Decoction could lower the fasting plasma glucose (FPG) level. The Xiaoke Decoction groups surpassed the western medicine groups regarding reduction in FPG levels (MD = −1.14; 95% CI: −1.36 to 0.92, P < 0.00001). Adding Xiaoke Decoction could lower the 2 h postprandial blood glucose (2hPG) level. The Xiaoke Decoction groups surpassed the western medicine groups regarding reduction in 2hPG (MD = −1.40; 95% CI: −1.61 to 1.19, P < 0.00001). Adding Xiaoke Decoction could lower glycated hemoglobin (HbA1c). The Xiaoke Decoction groups surpassed the western medicine groups regarding reduction in HbA1c (MD = −0.77; 95% CI: −0.95 to 0.58, P < 0.00001). It was found that adding Xiaoke Decoction could lower the traditional Chinese medicine (TCM) syndrome score. The TCM syndrome scores among patients in the Xiaoke Decoction group were lower than those among patients in the control group after treatment (MD = −4.90; 95% CI: −7.22 to 2.57, P < 0.0001). At the same time, we conducted a subgroup and sensitivity analysis of age and intervention duration on the heterogeneity of total efficiency, FPG, 2hPG, HbAlc, and TCM syndrome score outcome indicators. For detecting publication bias, an egger test was conducted. ConclusionCompared with western medicine alone, Xiaoke Decoction has more advantages for the treatment of type 2 diabetes with respect to total efficiency, FPG, 2hPG, HbAlc, and TCM syndrome score.

A Decoupling Network for Resonant and Non-Resonant Sub-1 GHz MIMO Mobile Terminal Antennas With Improved Compactness and Efficiency

In this work, the design procedure of a new decoupling network for different antennas is presented for mobile terminals operating in the Sub-1 GHz band (from 0.698 to 0.96 GHz). To evaluate its applicability for different resonant and non-resonant antenna types, two antenna elements have been chosen to be decoupled using the proposed decoupling network: a printed inverted-F antenna and a capacitive coupling element antenna. Simulation and measurement results showed that the decoupling network offer promising improvements in terms of impedance matching, port isolation, envelope correlation coefficient (ECC), and total efficiency. In addition, the antennas are also investigated with the ergodic capacity, multiplexing efficiency, gain, and diversity gain (both calculated using maximal ratio combining technique). Due to the contribution of the decoupling network, the ECC of both types of multiple antennas are less than 0.3, with a 30 % improvement in total efficiency and an inter-element spacing miniaturization of 34 %.

Experimental Verification of Fault Tolerant Operation Focusing on DC-Bus Battery Failure in Dual Inverter Motor Drive

Recently, a dual inverter motor drive feeding an open-end winding permanent magnet (PM) motor has been studied, aiming for the improvement of total efficiency and a fault tolerant function of hybrid and electric vehicles. The authors have studied the fault tolerant operation of the DC-bus battery, where the failed inverter is operated only with a capacitor across the DC-bus and a space vector modulation (SVM) is employed to regulate the capacitor voltage. In our previous research, the SVM techniques for the fault tolerant operation in a low-modulation-index have been proposed. However, it was difficult to have fault tolerance in a high-modulation-index case. The voltage margin in the fault situation is limited because the failed inverter is operated with the capacitor. In this paper, the SVM technique to achieve the fault tolerant operation in the high-modulation-index state is investigated. The novel point of this paper is that the proposed technique introduces a field-weakening control in order to reduce the command voltage vector within the controllable voltage region. The proposed technique was verified through experimental tests and its operational characteristics were compared with the normal operation, from the viewpoints of the total harmonic distortion (THD) and the efficiencies of the inverters and the motor.

A Meta-Surface Decoupling Method for Two Linear Polarized Antenna Array in Sub-6 GHz Base Station Applications

In this paper, an extremely compact two-element linear polarized multiple-input-multiple-output (MIMO) antenna array with a metasurface superstrate is proposed. Instead of using periodic square split-ring resonators which occupy larger space and which are incident angle variant, double-layer short wire is utilized as the unit cell of the metasurface. The metasurface is compact in size and effective in decoupling two nearby Bowtie antennas strongly coupled in the H-plane with the spacing of only 0.27 wavelength. After decoupling, the isolation between the two antennas has been improved from around 10 dB to more than 25 dB within the band of 2300 to 2690 MHz while their reflection remained below −15 dB. Moreover, the radiation pattern after adding the metasurface superstrate is well maintained with total efficiency improvement by about 10%, and the envelope correlation coefficient between the two antennas is reduced from 0.35 to below 0.12 within the whole band of interest. The proposed method can find plenty of applications in MIMO and 5G communication systems.

Hybridisation ratio for hybrid excitation synchronous motors in electric vehicles with enhanced performance

For electric vehicles (EVs) with severe acceleration requirement, the selected motor would be inevitably overdesigned to meet the acceleration requirement. To address this, the motor constant power speed ratio (CPSR) should be increased to remove part of the overdesign. There are different flux weakening techniques that are used to increase motor maximum speed (and increase the CPSR). Among them, hybrid excitation synchronous motor (HESM) advantages have been benefited in this study. CPSR depends on hybridisation ratio (HR) of the excitation system, and the motor inductance. The relation is analytically derived in this study. In addition to increasing CPSR, HR can control the place of motor high-efficient area over the efficiency map, which can increase EV total efficiency. A search algorithm has been developed, here, to find the optimal HR of a non-optimal HESM. The final design gives an efficient motor performance with less overdesign in drivetrain. Compared with the original permanent magnet synchronous motor, 4.1% improvement in total efficiency for an average city-highway driving cycle has been achieved, and 16% decrease in rated values of drivetrain elements is obtained.

A 13.56-MHz Wireless Power Transfer System With Enhanced Load-Transient Response and Efficiency by Fully Integrated Wireless Constant-Idle-Time Control for Biomedical Implants

In this paper, a complete wireless power transfer system with transmitter (TX) and receiver (RX) chips is presented. Both RX local and TX wireless output voltage regulations are achieved by the proposed constant-idle-time control without using any wires or additional discrete components, such as MCU, DAC, various kinds of controllers, and decoders, which were required in previous works. The system and circuitry design complexity is significantly reduced. Both TX and RX chips are fabricated in the TSMC 65-nm process with standard 2.5-V I/O devices, and the RX coil is fabricated using flexible printed circuits to demonstrate the performance for implantable applications. Up to 17.5% end-to-end total efficiency improvement is observed when enabling the wireless constant-idle-time controlled TX voltage regulation, and an instant load-transient response is also achieved. As a result, compared to previous works, this design achieves a higher total efficiency, a faster load-transient response, and a higher level of integration with a much lower system and circuitry design complexity.

Systematic Coiled-Tubing-Efficiency Improvement Reduces Operational Time

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 184779, “Consistent, Systematic Approach to Deepwater Coiled-Tubing-Efficiency Improvement Substantially Reduces Operational Time, Gulf of Mexico,” by Peter Weiland, SPE, Alexander Rudnik, SPE, and Eric Gagen, SPE, Schlumberger, prepared for the 2017 SPE/ICoTA Coiled Tubing and Well Intervention Conference and Exhibition, Houston, 21–22 March. The paper has not been peer reviewed. Deepwater coiled-tubing (CT) well interventions can benefit from significant rig-time reduction and cost savings associated with improved efficiencies of surface processes. Efficiency improvement requires a systematic approach and detailed analysis of each part of the process. The efficiency methodology allows for systematic improvement in all areas of CT operations, specifically for surface activities. The total efficiency solution described in this paper requires no additional cost to service providers, and results can be seen immediately. Deepwater Coiled Tubing The use of CT for well intervention can provide many downhole solutions throughout the life of a well. Although there is much discussion of the financial and technical aspects of CT in the industry, less conversation is directed toward the efficiency of CT surface processes. The expansion of analysis, specifically to CT process efficiency both before and after in-hole operations, is necessary for a holistic approach to total efficiency improvement. The stages of CT operation shown in green in Fig. 1 can be identified as five distinct surface activities. Design Methodology The first stage of the efficiency solution involved analysis of past performance. Some limited performance data were collected and reviewed, primarily on CT rig up, pressure testing, and transition time between CT and wire services (wireline and slickline). The underlying strategies of several widely accepted continuous-improvement programs, such as lean principles and the define/measure/analyze/implement/control methodology, were used to provide the link between performance and improvement. Low-performance areas and areas of recurring nonproductive time (NPT) were addressed through root-cause analysis and remedial-work plans that were focused on specific tasks. Mean-while, high-performance areas were analyzed to document the best practices for efficient operational execution so that efficiency gains could be realized for the duration of the campaign. Performance is compared with both baseline and previous-operation performance data so that trends and inconsistencies could be identified easily. Equipment Mobilization/Demobilization and Lifting The first stage of any CT operation involves mobilizing the required equipment to location. A typical CT spread may require 30 to 45 individual lifts to move equipment from the workboat to the rig. This first process, termed boat work and equipment spotting, is most commonly tracked by total time required to place the entire CT spread on deck.

Efficient Programmable Pulse Shaping for $X$ -Band GaN MMIC Radar Power Amplifiers

This paper presents a supply modulated $X$ -band 12-W peak power transmitter that maintains an average efficiency greater than 50% for various shapes of amplitude-modulated pulses. The main power amplifier is a two-stage GaN-on-SiC MMIC with a peak efficiency of 65%, while the pulse envelope modulator is a 95% efficient hybrid 3-b power DAC implemented with GaN-on-Si transistor switches. Envelope shaping of a pulsed waveform results in improved spectral confinement of greater than 15 dB for the first sideband compared with constant-envelope pulses, with over 20 points improvement in total efficiency. The combination of supply modulation and digital predistortion is shown to result in high composite (total) efficiency of over 55%, with simultaneous high dynamic range and with flexible digitally programmable pulse shaping.

Thermodynamic analysis and system design of a novel split cycle engine concept

The split cycle engine is a new reciprocating internal combustion engine with a potential of a radical efficiency improvement. In this engine, the compression and combustion–expansion processes occur in different cylinders. In the compression cylinder, the charge air is compressed through a quasi-isothermal process by direct cooling of the air. The high pressure air is then heated in a recuperator using the waste heat of exhaust gas before induction to the combustion cylinder. The combustion process occurs during the expansion stroke, in a quasi-isobaric process. In this paper, a fundamental theoretical cycle analysis and one-dimensional engine simulation of the split cycle engine was undertaken. The results show that the thermal efficiency (η) is mainly decided by the CR (compression ratio) and ER (expansion ratio), the regeneration effectiveness (σ), and the temperature rising ratio (N). Based on the above analysis, a system optimization of the engine was conducted. The results showed that by increasing CR from 23 to 25, the combustion and recuperation processes could be improved. By increasing the expansion ratio to 26, the heat losses during the gas exchange stroke were further reduced. Furthermore, the coolant temperatures of the compression and expansion chambers can be controlled separately to reduce the wall heat transfer losses. Compared to a conventional engine, a 21% total efficiency improvement was achieved when the split cycle was applied. It was concluded that through the system optimization, a total thermal efficiency of 53% can be achieved on split cycle engine.

Ion surface modification for space TWT multistage depressed collectors

An ion treatment system for space traveling wave tube (TWT) multistage depressed collectors (MDCs) has been built. Processes were investigated using oxygen-free, high-conductivity (OFHC) copper plates and MDCs in terms of the measurement of secondary electron emission ratio ( δ) and scanning electron microscope (SEM) analysis of surface texture. Measured δ for ion treated OFHC Cu plates, was found to be closely related to Mo deposition rate and spike texture observed on the SEM micrographs. For the optimized process, maximal δ from OFHC Cu plates was reduced to 0.6, less than a half of that of the untreated, while measured maximal δ from inner wall of MDCs varies from 0.64 to ∼1.0 depending on the geometry of the collector. With the treated four staged-MDCs, Ka-band TWTs have demonstrated a few percent of improvement in total efficiency.