Charge Pressure Research Articles

The Influence of the working fluid and Regenerator material on the Performance of the types Gamma Stirling Engine

In concentrated solar energy applications, the Stirling engine is the optimum option for extracting mechanical work. The engine's most notable features are minimal noise, vibration, and pollution, as well as its capacity to function with any external heat source, including biomass, solar energy, and industrial waste. The gamma-type STE-1008 Stirling engine is the subject of our research. This engine can handle a maximum charging pressure of 10 bar. The engine is divided into two sections (expansion and compression) and three heat exchangers (regenerator, cooler, and heater). The cooler is a finned aluminium heat exchanger with 144 internal fins, each with a cross-sectional area of 1 mm by 10 mm. The regenerator is fitted with a diameter of 31 m and a volumetric porosity of 90%. This investigation employed a random fiber with three different metals: stainless steel, copper, and aluminium. Nitrogen and air served as the working fluids. From the results, stainless steel, copper, and aluminium regenerators produced 583 W, 562 W, and 553 W, respectively. When nitrogen is utilized at 500 °C, the engine generates 11 N.m of torque compared to 8.5 N.m when air is used, and the engine has a thermal efficiency of 19% compared to 15% when air is used. The results of other researchers were used to compare and validate our model. With errors of no more than 12%, the results were close enough to the experimental data to be useful.

The investigation of effects on the engine performance characteristics of different channel geometries in the displacer cylinder for a beta-type Stirling engine with the slider-crank drive mechanism

This study was focused to develop a power generation system that could use renewable energy resources more efficiently. In accordance with this purpose, the design, manufacturing, and testing of a Stirling engine with a β-type slider-crank drive mechanism were carried out. Helium, nitrogen, and air were utilized as working fluids, and experimental studies were performed at various charge pressures. Moreover, the effects of three different channel geometries in the displacer cylinder on the performance were researched. The maximum power was obtained as 160.5 W in a 120-slot channel displacer cylinder in the helium working fluid at a charge pressure of 4 bar and 400 rpm engine speed. The highest torque was found to be 7.92 Nm in a 66-slot channel displacer cylinder in the helium working fluid at the aforementioned charge pressure and 100 rpm engine speed. The lowest engine power output among the maximum engine powers was obtained to be 48.3 W when air was used as a working fluid at a pressure of 4 bar and an engine speed of 200 rpm, using a smooth displacer cylinder. Use of channels in the displacer cylinder and the increased number of channels had positive effects on engine performance. It was determined that the maximum engine power output obtained in the experimental studies was 46.0% and 49.86% higher in the 66-slot channel, and 120-slot channel cylinders, respectively, compared to the smooth displacer cylinder. It has been observed that when the number of channels on the displacer cylinder was increased by approximately 81.8%, an increase of approximately 2.62% was obtained in the engine power output. This situation revealed that optimization of the number of channels is important.

Advances on a free-piston Stirling engine-based micro-combined heat and power system

As a promising supplement to traditional central electric generation technologies, a distributed combined heat and power (CHP) system is conducive to renewable energy deployment and mitigation of carbon emissions. Among the candidate technologies, the free-piston Stirling engine (FPSE)-based CHP technology is competitive in micro- or small-scale applications. In this work, the performance of a FPSE-based micro-CHP system is improved through a combination of numerical optimization and experimental validation. First, by using a third-order model and thermoacoustic analysis, the impact of regenerator length, displacer moving mass, and force factor of the alternator on the free-piston Stirling generator (FPSG) inside acoustic field, supplied thermal power and exergy loss is studied numerically. The numerical results indicate a rational increase of the force factor, the regenerator length as well as the displacer moving mass is positive for improving the CHP performance. Based on the numerical optimization, the FPSG prototype is updated accordingly, and adequate measurements of the internal acoustic field of the FPSG have been deployed. Then, a series of experiments are conducted to evaluate the CHP performance of the refurbished FPSG prototype. The experimental results show that the highest CHP efficiency reaches 95.7%, the output electric power is 4.03 kW, and the corresponding thermal-to-electric efficiency is 32.2% when the average temperature of supply and return water is as high as 75 °C. Compared with the work before upgrade, the output electric power and CHP efficiency are improved significantly by 39% and 9.4%, respectively. An insight into the impact of the temperature difference between supply and return water indicates that it has a slight impact on electric power generation, especially under higher charge pressure. In contrast, thermal production exhibits an apparent negative correlation with the temperature difference.

Modelling and optimization of liquid air energy storage systems with different liquefaction cycles

Liquid air energy storage (LAES) is one of the large-scale mechanical energy storage technologies which are expected to solve the issue of renewable energy power storage and peak shaving. As the main energy loss of a standalone LAES occurs in the liquefaction process, this paper focused on the thermodynamic analysis of LAES systems with different liquefaction cycles. Six liquefaction cycles were considered. To obtain a higher system efficiency and fair comparative analysis of the performance of different LAES systems, authors used a combined genetic algorithm (GA) and HYSYS process simulation method to perform the multi-parameters global optimization. Subsequently, energy and exergy analyses were conducted on the optimized LAES systems. The results show that the system efficiency of the LAES based on turbo-expander refrigeration (i.e., the Claude cycle, Kapitza cycle, and Heylandt cycle) increases with an increase in the split ratio. The LAES with Kapitza liquefaction cycle shows the most competitive system performance compared with the other liquefaction cycles based-LAES systems. The LAES with Kapitza liquefaction cycle exhibits the lowest optimal charging pressure of 10.73 MPa and achieves the highest round-trip efficiency, system storage exergy efficiency, and system recovery exergy efficiency of 60.02 %, 86.41 %, and 84.98 %, respectively. The obtained GA optimization and thermodynamic analysis results of LAES systems with different liquefaction configurations can provide significant theoretical guidance for further industrial applications of LAES.

Parametric study and design optimization of a kW-class beta-type Stirling engine

• A theoretical model for predicting shaft power and engine speed is proposed. • Effect of geometric parameters on local maximum shaft power is studied. • A kW-class beta-type Stirling engine is tested and optimized. • The maximum shaft power was increased to 1503 W after optimization. A Stirling engine is an external combustion engine that can be operated using different types of heat sources. Stirling engines can be applied in many renewable energy fields. The purpose of this study was to optimize the design of a kW-class beta-type Stirling engine with a rhombic drive mechanism for a concentrated solar power system. In this study, an energy method and a modified non-ideal adiabatic model were used to predict the shaft power and operating speed of the proposed engine. The simulation results obtained using the model were validated by the experimental results. The experimental results revealed that the instantaneous maximum power of the proposed engine could reach 1312 W at 1390 rpm under a helium pressure of 6 bar and heating temperature of 650 °C. On the basis of the experimental results, the local maximum shaft power was obtained using the quadratic interpolation method. Therefore, the effect on shaft power of the engine speed could be ignored, thereby reducing the calculation time. The effects of the charged pressure and design parameters of the heat exchanger on local maximum shaft power were studied. Multivariable optimization of the prototype engine was conducted based on the results of the quadratic interpolation method. Both the simplified conjugate gradient method and the variable step size conjugate gradient method were adopted as optimization algorithms. The results indicated that the number of iterations required in the variable step size conjugate gradient method to approach the optimum point was approximately one-third that required in the simplified conjugate gradient method. The results demonstrate that the maximum shaft power of the prototype engine can be further increased from 1137 W to 1503 W. Thermal efficiency and mechanical efficiency can also be increased to 13.5 % and 94.3 %, respectively.

Techno-economic assessment on a multi-stage compressed carbon dioxide energy storage system with liquid storage

Energy storage system is capable of solving the intermittent and volatility problems of renewable energy and can also perform peak-shaving and valley-filling of the grid. A compressed gas energy storage by storing liquid carbon dioxide possesses the merits of high energy density and competitive efficiency, which makes it a promising overground energy storage technology. However, the problems this technology faced with are narrow compression/expansion processes, high storage pressure and liquefying the gaseous carbon dioxide. Therefore, a liquid carbon dioxide storage system with low-pressure storage and extended working process is suggested in this work. Furthermore, a comprehensive evaluation is conducted on the system from both thermodynamic and economic aspects. The effects of charge and discharge pressures, CO2 mass flow ratio, system operation years, annual cycle times, discount rate, inflation rate and electricity price in different cities on system performance are analyzed. The results indicate that by increasing the charge and discharge pressures there is a maximum round trip efficiency of 56.23% and a peak energy density of 19.90 kWh/m3, respectively. In addition, the analysis of the electricity prices in four different cities on the economic action over the system shows that Shenzhen has the lowest levelized cost of energy (0.0907 $/kWh), Beijing can obtain the highest net present value of 35.314 million dollars and complete cost recovery in the shortest time of 4.84 years.

Исследование влияния параметров гидропневмоаккумулятора на работу устройства управления положением цилиндрической щётки коммунальной машины

The article is devoted to the actual problem of improving the quality of cleaning roads and sidewalks by communal machines with brush working equipment. One of the main parameters of the working process of a communal machine with brush working equipment, which determines the cleaning efficiency and brush life, is the brush pressing force against the surface to be cleaned. In order to ensure the highest efficiency of the cleaning process during the operation of the communal machine, it is required to maintain a certain value of the brush pressing force. During the operation of a communal machine equipped with brush implements with track rollers, the pressing force can vary significantly. To maintain the required value of the brush pressing force against the surface to be cleaned, a device for controlling the position of the brush working equipment using a hydropneumatic accumulator connected to the rod end of a standard hydraulic cylinder is proposed. The pressure of the working fluid created by the hydropneumatic accumulator and acting on the piston of the hydraulic cylinder creates a force acting on the brush working equipment, which makes it possible to provide the necessary force for pressing the brush to the surface to be cleaned. The performance indicators of the device for controlling the position of the brush working equipment depend on the selected values of the design parameters of its elements, including the parameters of the hydropneumatic accumulator. The dependences of the deviation of the brush pressing force from the required value during the vertical movement of the brush working equipment on the useful volume, the initial charging pressure and the maximum pressure of the hydropneumatic accumulator are obtained. A method is considered to reduce the deviation of the brush pressing force from the required value by connecting an additional volume to the gas cavity of the hydropneumatic accumulator.

Comparative study of the effects of increasing heat transfer area within compression and expansion chambers in combination with modified pistons in Stirling engines. A simulation approach based on CFD and a numerical thermodynamic model

The aim of this research is to ascertain the potential benefits of increasing heat transfer area in the expansion and compression spaces of Stirling engines. This is achieved, as proposed in an accepted patent, by simultaneously attaching pins or fins to the chamber walls and modifying the geometry of the displacer. Different configurations involving pinned and finned surfaces were proposed for comparison with a hollow cylindrical chamber. In order to compute the heat transfer rate as well as the convective heat transfer coefficient for each suggested geometry, a CFD (Computational Fluid Dynamics) model was run under different temperatures, displacer speeds and pressures. For a selected geometry based on longitudinal cylindrical pins, the computed heat transfer coefficients were correlated with input parameters in order to obtain a simple equation. The equation was subsequently introduced into a three-camera second-order thermodynamic model of a gamma Stirling engine with crankshaft mechanism. Five different cases were evaluated. The models were run for different operational conditions (speed and charge pressure), for a hot wall temperature of 493 K and a cold wall temperature of 293 K. Pressure was varied from 1 to 2.5 atmospheres and the engine rotational speed ranged between 50 and 1000 rpm. Results showed an increase in engine power between 1.3 and 2.5 times when compared to a conventional engine without heat exchangers.

Study on thrust performance of small water rocket launch

For water rocket test of low cost, quick assembly and simple, based on the single water rocket, using Bernoulli equation, the ideal gas adiabatic model and mass conservation theorem, this paper derived both the calculation method of thrust rocket the bottle under the different initial water volume ratio of water pressure, and the rule about how the water rocket thrust and pressure performance change. It is found that the pressure, the jet velocity of the water relative to the water rocket body and thrust of water rocket will decrease with the decrease of water amount under different initial charging pressure and different initial water amount. If the initial pressure is higher, the water rocket will gain more energy and launch faster; However, it doesn’t mean that the more initial water storage ratio is, the better. The maximum velocity obtained by water rocket under the same initial pressure increases first and then decreases with the initial water storage ratio and the optimal initial water storage ratio increases with the increase of initial pressure. According to data calculation, the numerical value increases with the increase of initial pressure. The optimal performance of water rocket can be obtained by taking the maximum pressure and the corresponding optimal initial injection water when the water rocket body is allowed.

Future refrigerants with low global warming potential for residential air conditioning system: a thermodynamic analysis and MCDM tool optimization.

Increasing CO2 emission due to the practicing of high global warming potential (GWP) refrigerant like R22 in split air conditioning (AC) units needs the best substitute to match with environment and safety protocols along with good energy efficiency. In this study, 14 alternative refrigerants have been chosen to replace R22 in a 1.5 TR capacity of split AC from the existing studies. The performance of each refrigerant has been analysed thermodynamically and compared their results with R22 by accounting for discharge temperature, power consumption, coefficient of performance (COP), total equivalent warming impact (TEWI) index, and life-time cost. Overall from this theoretical analysis, it was observed that the best refrigerant for each considered measure is not unique; for example, R290 was best in terms of refrigerant charge and discharge pressure, while R444B was chosen to be superior in terms of COP, TEWI, and life-time cost. Therefore, a multi-criteria decision-making methodology tool-based optimization has been carried out for selecting a single superior refrigerant for the future by considering thermal properties, COP, TEWI, and life-time cost. Results of the evaluation based on the distance from average solution envisage R290 and R1123 as superior and worst choices to replace R22.

Optimization of a cryogenic liquid air energy storage system and its optimal thermodynamic performance

For grid-scale intermittent electricity storage, liquid air energy storage (LAES) is considered to be one of the most promising technologies for storing renewable energy. In this study, a steady-state process model was developed for an LAES, by combining a Linde liquefaction process and an open Rankine power cycle. To investigate the system performance and achieve global optimization, a single-factor analysis approach and multifactor genetic algorithm (GA) optimization model were built using MATLAB software. The effects of the charging pressure, storage pressure, discharging pressure, and isentropic efficiency of the compressor/turbine on the LAES performance parameters, such as the inlet temperature of the Joule–Thomson valve, round-trip efficiency (RTE), liquefaction ratio (LR), and power consumptions in the compressor, cryo-pump, and turbine, were investigated. Subsequently, the optimal conditions were obtained using the GA optimization method to achieve the optimal performance of the LAES. The results showed that the charging pressure, discharging pressure, and isentropic efficiencies of the compressor and turbine had significant effects on the RTE; an increase in the discharging pressure resulted in an improved expansion power output; the GA optimization could achieve RTE, LR, the system energy storage and recovery exergy efficiencies of 53.33%, 86.96%, 81.00%, and 78.16%; the power consumption in the compressor of GA optimization was 10.02% maximum saving. The proposed optimization method can be used to further explore the global optimization of cryogenic energy storage systems, such as different-layout LAES systems and different cryogenic liquefaction media energy storage systems.

A heat-driven combined cooling and heating system based on thermoacoustic technology

Energy crisis and environmental pollution have become global issues. This study reported a heat-driven combined cooling and heating system based on thermoacoustic technology, which adopted two units of thermoacoustic engine and cooler cores to improve the efficiency. This system can be used as a refrigerator and a heat pump at the same time. Experimental results showed that with a charging pressure of 10 MPa, a high temperature of 300 °C, and a medium temperature of 45 °C, cooling power ranging from 0.61 to 3.89 kW and coefficient of performance varying from 0.08 to 0.30 with low temperature changing from −30 to −5 °C were achieved when the system was working as a refrigerator. Meanwhile, under a low temperature of −30 and −10 °C, a heating power of 7.85 and 14.3 kW with a medium temperature of 45 °C could be achieved corresponding to a coefficient of performance of 1.08 and 1.24 when the system was working as a heat pump. These experimental performances show remarkable advantages and a promising prospect for thermal energy utilization in the future.

Charged strange stars with dust and phantom regimes in Rastall gravity

In this paper, we are focused on studying the possibility of providing a new well-behaved class of exact solutions for viable anisotropic stellar systems with dust and phantom regimes in the framework of Rastall gravity theory. This gravity theory modifies the matter sector only, incorporating new ingredients to the physical parameters that describe the model like charge density, electric field, density, and pressure components. Furthermore, other significant amounts are influenced, such as subliminal speeds of the pressure waves in radial and transversal directions, observational parameters such as the surface redshift associated with the total mass M and the radius R of the compact stellar configurations. Likewise, a transcendent mechanism such as equilibrium via generalized Tolman–Oppenheimer–Volkoff equation and stability of the stellar system is upset. The unidentified constraints are evaluated via the boundary conditions along with the dust and phantom models to describe as exterior space–times considering experimental statistics of five different stars i.e., EXO 1785 - 248, SMC X - 1, SAX J 1808.4 - 3658, 4U 1538 - 52, and HER X - 1. Various physical aspects have been analyzed with the help of modified dynamical equations. Exclusively, all the stellar configurations under observations are realistic, stable, and are free from all singularities. After witnessing the minor differences between our proposed models in both cases, Andréasson’s limit M≤R/3+R/9+Q2/3R has been fulfilled as required by the charged stellar structures. In such an astrophysical scenario, our new results provide circumstantial evidence in favor of super-massive pulsars.

Influence of Charging Oil Condition on Torque Converter Cavitation Characteristics

Cavitation inside a torque converter induces noise, vibration and even failure, and these effects have been disregarded in previous torque converter design processes. However, modern torque converter applications require attention to this issue because of its high-speed and high-capacity requirements. Therefore, this study investigated the cavitation effect on a torque converter using both numerical and experimental methods with an emphasis on the influence of the charging oil feed location and charge pressure. Computational fluid dynamics (CFD) models were established to simulate the transient cavitation behaviour in the torque converter using different charging oil pressures and inlet arrangements and testing against a base case to validate the results. The CFD results suggested that cavitating bubbles mainly takes place in the stator of the torque converter. The transient cavitation CFD model yielded good agreement with the experimental data, with an error of 7.6% in the capacity constant and 7.4% in the torque ratio. Both the experimental and numerical studies showed that cavitation induced severe capacity degradation, and that the charge pressure and charging oil configuration significantly affects both the overall hydrodynamic performance and the fluid behaviour inside the torque converter because of cavitation. Increasing the charge pressure and charging the oil from the turbine-stator clearance were found to suppress cavitation development and reduce performance degradation, especially in terms of the capacity constant. This study revealed the fluid field mechanism behind the influence of charging oil conditions on torque converter cavitation behaviour, providing practical guidelines for suppressing cavitation in torque converter.

Numerical analysis and experimental research of a 2W/35 K Stirling-type pulse tube cryocooler

Cooling to the temperature of liquid nitrogen to liquid hydrogen is a necessary working prerequisite for some infrared detectors. The development of compact and efficient miniature cryocoolers is of great significance for the space application of the detectors. The pulse tube cryocooler driven by a dual-opposed linear compressor is prospective in space applications due to the advantages of no low-temperature moving parts, compact structure, and high reliability. In this paper, a 2W/35K Stirling-type pulse tube cryocooler with a single-stage structure has been designed and tested. The influences of structural parameters of the phase shifters such as inertance tube, as well as the operating parameters such as operating frequency and charging pressure, on the cooling performance were investigated through numerical calculations and experiments.

A preliminary study of 4He convective heat switches

Heat switches are key components in sub-kelvin refrigeration. It is widely used in cryogenic systems, such as controlling thermodynamic cycle, coupling/decoupling redundant cryocoolers, accelerating the cooling of cryogenic components and so on. Convective heat switch features simple structure, no moving parts and great thermal conductance, which is mainly used to precool cryogenic components. In order to accelerate the pre-cooling of a test platform to 4K, the passive convective heat switch is investigated in this paper, which consists of a circuit comprising two identical stainless steel tubes and two copper cavities respectively connected to the cold and warm stages. The ON/OFF state of the switch is realized by the presence/absence of a gravity-driven convective helium-4 gas loop. Several convective heat switches with different cavity structures and charge pressures are designed and assembled. The preliminary experimental results on thermal conductance are presented. With a typical dimension of a cylindrical cavity with a diameter of 28mm and a height of 16.8mm, a stainless steel tube with a diameter of 9.6mm and a length of 72mm, thermal conductance of 40-50mW/K in ON state has been obtained.

Development of a 2∼4 K closed-cycle JT cryocooler for space application

Cryogenic system proving cooling capacity at liquid helium temperatures is one of the key technologies for space exploration missions. A closed-cycle Joule-Thomson cryocooler capacity of providing different cooling powers at 2∼4 K is developed in our lab. The cryocooler is precooled by a two-stage thermal coupled pulse-tube cryocooler with active phase shifter and driven by multi-stage valved linear compressors. The lowest temperature about 2.5 K and more than 50 mW at about 4.0 K can be obtained by adapting the suited charging pressures. The two-stage pulse tube cryocooler can provide pre-cooling capacity at 17 K and 76 K, respectively with an input power of about 350 W. A large pressure ratio of about 26 and a mass flow rate of 6.7 mg/s can be provide by the multi-stage valved linear compressors with a charge pressure of 0.6 MPa and a total electrical power of less than 110 W. The cooling-down time for the cryocooler from room temperature to about 4 K is less than 10 hours. The cooling system can provide a required cryogenic environment for future space applications.

Experimental Study on Microscale Simulation of Oil Accumulation in Sandstone Reservoir

It is generally believed that conventional hydrocarbon accumulates in sandstone traps after migrating at a certain distance. Unconventional hydrocarbon only migrates at a short distance before accumulation or being imbibed in the tiny pores of shale and tight sandstone reservoir, and there is no obvious trap boundary. There are also different views on the time interval between hydrocarbon accumulation and migration. In this paper, microscale simulation experiments are used to study the process of oil accumulation during migration. In the single pore-throat model, oil can 100% saturate the pore in the process of migration with continuous oil supply. In the plane sandstone model, when oil migrates through the entire model, the oil-bearing area can reach more than 50% of the model area. In the sandstone reservoir model, when the front edge of oil migrates through the entire sandstone layer, the oil saturation near the injection point can reach more than 90%, while the oil saturation of the front part of the model is only about 50%. It shows that, in sandstone reservoir, when there are sufficient oil source and continuous charging pressure, the oil saturation near the charging point continues to increase during oil migration, and the range of high oil-bearing area continues to expand. Therefore, there can be a certain number of hydrocarbon accumulations along the migration path in sandstone reservoir under sufficient oil supply and continuous charging pressure, rather than just in traps.

Experimental investigation of the effects of hot-end and cold-end connection on the performance of a gamma type Stirling engine

External combustion Stirling engines are considered as an alternative to the solution of increasing energy and environmental problems due to their ability to work with any heat source and to be an efficient energy conversion system. In this study, the effects of hot-end and cold-end connections of power and displacer cylinders on the performance of a gamma-type Stirling engine (GTSE) were investigated experimentally. The effects of the connection type between the power and displacer cylinders on the engine performance were compared at the same operating conditions without making any structural modifications to the engine. The performance tests were conducted using helium as the working gas at different charging pressures. The experimental results show that the maximum values of the engine torque and output power were obtained at a certain charging pressure for both hot-end and cold-end connected engines. Compared to the cold-end connection (CEC) engine, the maximum torque and output power increased in the hot-end connection (HEC) engine at the same temperature range. In the HEC engine, the maximum engine torque and power were achieved as 0.5665 Nm and 23.35 W, resulting in an increase of 68.4% and 84.7% compared to those of the CEC engine, respectively.

Asymmetric Electrokinetic Energy Conversion in Slip Conical Nanopores.

Ion current rectification (ICR) phenomena in asymmetric nanofluidic structures, such as conical-shaped nanopores and funnel-shaped nanochannels, have been widely investigated in recent decades. To date, the effect of asymmetric nanofluidic structures on electrokinetic power generation driven by the streaming current/potential has not been explored. Accordingly, this study employed a numerical model based on the Poisson equation, Nernst–Planck equation, and Navier–Stokes equation to investigate the electrokinetic energy conversion (EKEC) in a conical nanopore while considering hydrodynamic slippage. The results indicated that the asymmetric characteristics of streaming current (short-circuit current), streaming potential (open-circuit voltage), maximum power generation, maximum conversion efficiency, and flow rate were observed in conical nanopores under the forward pressure bias (tip-to-base direction) and reverse pressure bias (base-to-tip direction) once the nonequilibrium ion concentration polarization (ICP) became considerable. The rectification behaviors in the streaming current, maximum power, and maximum conversion efficiency were all shown to be opposite to those of the well-known ICR in conical nanopores. In other words, the reverse pressure bias revealed a higher EKEC performance than the forward pressure bias. It was concluded that the asymmetric behavior in EKEC is attributed to the asymmetric electrical resistance resulting from asymmetric ion depletion and ion enrichment. Particularly, it was found that the decrease in electrical resistance (i.e., the change in electrical resistance dominated by the ion enrichment) observed in the reverse pressure bias enhanced the maximum power and maximum conversion efficiency. The asymmetric EKEC characteristics became more significant with increasing slip length, surface charge density, cone angle, and pressure bias, especially at lower salt concentrations. The present findings provide useful information for the future development of EKEC in engineered membranes with asymmetric nanopores.