Maximum Volumetric Efficiency Research Articles

Biodiesel Production Process Using Plasma Method on Engine Performance and Exhaust Gas Emissions

Crude Palm Oil is one of the renewable energy sources that is widely used as an environmentally friendly energy source, one form of utilization is by processing crude palm oil into biodiesel. However, biodiesel has drawbacks in terms of performance which is less good than fossil fuels. This study aims to improve the performance of the engine produced by biodiesel and maximize the utilization of crude palm oil in biodiesel. In improving the performance of diesel engines, the treatment method used in producing biodiesel affects the physical properties of the biodiesel produced. This study uses a mixture of Dexlite fuel with plasma biodiesel in a ratio of 1:1, which produces B50 biodiesel. To measure the performance using a TV1 diesel engine and a gas analyzer OPA 100 with a compression ratio of 1:18, 1:14, and a load of 1 kg, 3 kg, 5 kg, 7 kg, and 9 kg. The results showed that the maximum effective power (BP) occurred at a load of 9 kg with a ratio of 1: 14, which was 2.38 kW, and the minimum specific fuel consumption (SFC) occurred at a compression ratio of 1: 18 and loading 9 which is 0.240 Kg/kWh, the maximum volumetric efficiency (ηvo) occurs at 9 kg loading with a compression ratio of 1: 14 with the addition of 0% methanol solvent which is 70.61%, and thermal efficiency (ηth) maximum loading occurred at 9 kg loading with a compression ratio of 1: 18 using 0% methanol solvent, which is 44,74%.

Surrogate-Based Multi-Objective Optimization of Flux-Focusing Halbach Coaxial Magnetic Gear

Due to their contact-free and low-maintenance features, magnetic gears (MGs) have been increasingly investigated to amplify the torque of electric motors in electric vehicles (EVs). In order to meet the requirements of propelling EVs, it is essential to design an MG with a high torque density. In this paper, a novel flux-focusing Halbach coaxial MG (FFH-CMG) is proposed, which combines the advantages of flux focusing and Halbach permanent magnet (PM) arrays. The proposed structure has a higher torque performance and greater efficiency than conventional structures. A multi-objective design optimization based on a surrogate model is implemented to achieve the maximum volumetric torque density (VTD), torque-per-PM volume (TPMV), and efficiency, as well as the minimum torque ripple, in the proposed FFH-CMG. The employed optimization approach has a higher accuracy and is less time-consuming compared to the conventional optimization methods based on direct finite-element analysis (FEA). The performance of the proposed FFH-CMG is then investigated through 2D-FEA. According to the simulation results, the optimized FFH-CMG can achieve a VTD of 411 kNm/m3, and a TPMV of 830 kNm/m3, which are significantly larger than those of the existing MGs and make the proposed FFH-CMG very suitable for EV applications.

Development of Ultra-High-Efficiency Medium-Capacity Chillers with Two-Stage Compression and Interstage Vapor Injection Technologies

Chillers are widely used in commercial buildings for air conditioning, and their energy consumption is the main contribution to the building’s carbon emissions. Currently, the COPs of small- and medium-capacity screw chillers are still generally lower than 6.5, whereas large-capacity commercial centrifugal chillers have achieved an ultra-high energy-efficiency level of COP ≥ 7.0. To achieve an ultra-high energy efficiency of COP ≥ 6.5 in medium-capacity chillers, the authors developed a 200 RT screw chiller by adopting the technologies of two-stage compression and interstage vapor injection. The whole development process, including the design, simulation, analysis, and experiment, is presented in this paper. It was found that the two-stage compression technology could effectively boost the performance of the chiller’s compressor to a maximum volumetric and adiabatic efficiency of 99% and 80%, respectively. With the interstage vapor injection technology, the chiller’s cooling capacity and COP were increased by more than 11% and 8%, respectively. When the use of these two technologies was combined, the maximum COP of the chiller reached 7.17. Additionally, under these working conditions, the COP and integrated part-load value (IPLV) were 6.74 and 10.04, respectively. In all, the combination use of vapor injection and two-stage compression technologies shows great potential to improve the performance of chillers. The work and conclusions described here might provide an effective reference for the future development of high-efficiency small- and medium-capacity screw chillers.

Optimization of a Spark Ignition Engine Knock and Performance Using the Epsilon-Constrained Differential Evolution Algorithm and Multi-Objective Differential Evolution Algorithm.

Since the advent of the internal combustion engine, knock has been a vital issue limiting the thermal efficiency of spark ignition engines under heavy load conditions. The occurrence of knock is also directly influenced by several operating parameters simultaneously. In order to investigate the effects of multiple variables on economic performance and power performance under knock limits, this study adopts single-objective optimization and multi-objective optimization methods to optimize the engine operating parameters, including exhaust gas recirculation rate, exhaust valve timing, spark timing, and intake valve timing. The optimization aims to obtain maximum volumetric efficiency, brake mean effective pressure, and minimum brake specific fuel consumption on the knock limit. First, based on the bench test data at the operation point 2800 rpm and 11.42 bar, a one-dimensional simulation engine model is established in GT-power software and verified. Second, four engine operating parameters are input into the GT-power model as controlled parameters. The epsilon-constrained differential evolution algorithm and the multi-objective differential evolution algorithm are employed to optimize the above four parameters to minimize the knock index and the damage to engine performance due to knock suppression, respectively. Finally, the results show that the two optimization algorithms optimize four parameters. The results of the epsilon-constrained differential evolution algorithm indicate that the decreasing extent of the knock index is 73.3%. In addition, the decreasing extent of brake mean effective pressure is 10.2%. What is more, the increased brake specific fuel consumption is only 0.07%. The multi-objective differential evolution algorithm gives a set of nondominated Pareto optimal solution sets. The optimal solution has a 64.4% decrease in the knock index, a 5.78% decrease in brake mean effective pressure, and a 1.45% decrease in brake specific fuel consumption.

Experimental research on performance of an oil-free moving-coil symmetrical dual-piston linear compressor for the J - T throttle refrigerator

In order to improve the efficiency of the Joule-Thomson (J-T) throttling refrigerator, an oil-free symmetrical dual-piston moving-coil linear compressor was developed, and its principle was demonstrated in detail. As the core component of the J-T throttling refrigerator, the linear compressor provides the pressure ratio and mass flow rate required by the throttling cycle. The linear compressor prototype was tested with nitrogen to evaluate its performance at different pressure ratios, strokes, and driving frequencies. Key performance parameters have been obtained, and the experimental results show that the input power is 175.2 W, the mass flow is 1.128 g/s, the unit power mass flow is 6.438 mg/s/W, the motor efficiency, volumetric efficiency, isentropic efficiency, and isothermal efficiency is 87.7%, 81.5%, 74.9%, and 63.7% at the design parameter (pressure ratio of 3.0, stroke of 10.0 mm, frequency of 60.0 Hz), respectively. The maximum mass flow rate is 1.742 g/s, and the maximum motor efficiency, volumetric efficiency, isentropic efficiency, and isothermal efficiency is 88.1%, 94.0%, 81.2%, and 73.4%, respectively. The symmetrical dual-piston linear compressor brings large-capacity and high efficiency, which provide a useful attempt and reference for the optimization of the linear compressors for the J-T throttling refrigerator.

Maximizing volumetric efficiency using stochastic optimization techniques for internal combustion engines

The volumetric efficiency of internal combustion engines quantifies the effectiveness of the admission process, whereas the thermal efficiency quantifies the amount of work generated based on the total energy released by the fuel. A method to optimize these efficiencies is by changing the valve timing. In this study, the parallelized particle swarm optimization method is implemented to maximize the volumetric efficiency, and its performance is compared with the differential evolution method. Calculations are performed using a parallelized computational code comprising a one-dimensional model for unsteady compressible gas flow in the intake and exhaust ducts, a single-zone combustion model for the in-cylinder process, and optimization routines based on particle swarm optimization and differential evolution techniques. In both optimizations, the design variables are the opening and closing angles of the intake and exhaust valves. Both optimization methods reach the same maximum volumetric efficiency, but the particle swarm optimization presents a smaller deviation from the mean values and better performance in terms of computational time. In addition, a higher volumetric efficiency is associated with higher values of the exhaust valve opening angle and intake valve closing angle at speeds of 2000 and 3000 rpm, respectively. Finally, it can be concluded that both optimization methods can optimize the volumetric efficiency and reach the same maximum value; however, the particle swarm optimization performs better in terms of the computational time and exhibits fewer deviations from the mean values.

A Novel Oil-free Dual Piston Compressor Driven by a Moving Coil Linear Motor with Capacity Regulation Using R134a

Improving compressor efficiency is very important to save energy and reduce greenhouse gas emissions. A novel oil-free dual piston compressor prototype driven by a moving coil linear motor was developed, and its working principle was described in detail. The prototype was integrated with a test rig to measure the operation characteristics, the compressor efficiencies and the coefficient of performance (COP). The results show that the dual piston structure results in extraordinary sinusoidal gas force and electromagnetic force and significantly reduces piston offset, which is completely different from the traditional single piston structure. Compared with the variable frequency method, the variable stroke method has lower energy consumption and a higher COP, which is more suitable to cooling capacity regulation for the prototype. The maximum COP, motor efficiency and volumetric efficiency are 5.34, 87.9% and 79.1%, respectively, under the design condition (the evaporation pressure is 0.35 MPa, and the pressure ratio is 2.54). The COP of the linear compressor is 38%, 24% and 12% higher than the commercial crank-driven reciprocating compressor at the pressure ratios of 2.54, 2.80 and 3.90, respectively, which reflects the efficiency advantage of the dual piston linear compressor in household refrigeration.

Experimental Investigation of Leakage in the Modified Revolving Vane Expander

Abstract This study focuses on the leakage characteristics of a modified revolving vane expander (M-RVE) using both static and dynamic leakage analysis. The no-expansion scenario showed a maximum volumetric efficiency of 18.7% was achieved at 5.5 bar(g) suction pressure, showing the severity of internal leakages. The blocker angle study demonstrated the importance of the correct opening-angle selection to avoid under or over-expansion. The maximum volumetric efficiencies for opening angles of 94 deg and 145 deg were 2.8% and 8.3%, respectively, at suction and discharge pressures of 6.5 bar(g) and 1 atm, respectively. The static leakage test demonstrated that the M-RVE housing was properly sealed, and the observed leakage in the dynamic test was mostly due to internal leakages. The results showed that the leakages through the radial clearance, endface, and vane side gaps make up 54%, 33%, and 8.5% of the overall leakage. Comparison between the theoretical and experimental data of the leakages through the radial clearance gap showed significant deviations at higher suction pressures. The reasons are thought to be due to the shafts' tilt, and the cylinder and rotor head deflections. It is believed that the deflection of the shaft created new leakage paths or changed the geometry of the current paths.

Optimization of the intake manifold of the Royal Enfield 500 electronic fuel injection engine

Intake manifold determines the charge flowing or the mass flow rate of the fuel and air mixture, which greatly influenced the volumetric efficiency of an engine. It has a great impact on engine power and torque. They are greatly affected by degree to which cylinders are charged & geometrical parameters of intake manifold. Every specified engine has its specific engine speed and it can be optimized with the help of the intake manifold geometry. Current work aims to study the effects of various designs of Intake manifolds for a naturally aspirated Royal Enfield EFI500 engine and to increase volumetric efficiency for FSAE related competitions, by doing CFD simulations and tuning of runner length. The objective is to increase the volumetric efficiency of the engine assuming a standard restriction of 20mm diameter to limit the overall power output. After CFD on intake manifold, results obtained in the least pressure drop and hence maximum volumetric efficiency.

Modeling of solid-liquid flow inside conical diverging sections using computational fluid dynamics approach

In a slurry pipeline, the diverging sections are an important pipe fitting and also a cause of major pressure loss and sometimes flow separation. To address this potential issue, the complex solid-liquid flow of coal water slurry through conical diverging sections is simulated using the computational fluid dynamics approach. Nine different geometries of the diverging sections are analyzed in the present study. The length of the diverging section is the key variable in the geometric variations and ranges from 0.05 m to 0.6 m. The influx velocity at the entrance of all the diverging sections is varied in the range of 0.5 m/s to 5 m/s. The mass concentration of the solids dispersed inside the liquid phase is varied from 10 to 60%. The results generated by the computational fluid dynamics tool are in good agreement with the experimental data. The design of the diverging section is evaluated based on results obtained for three characterization parameters viz. pressure recovery coefficient, head-loss across the diverging section and volumetric efficiency. The 0.3 m long diverging section is found to be the optimum design for best pressure recovery, maximum volumetric efficiency and lowest head-loss.

Multi-objective optimization of the volumetric and thermal efficiencies applied to a multi-cylinder internal combustion engine

The engines produced with valve timing systems have been growing in recent years, given the growing demand to improve their operation and efficiency. Certain operating conditions of valve timing engine increasing volumetric efficiency have a reduction in thermal efficiency. This study aims to apply multi-objective optimization to find conditions for opening and closing valves of maximum volumetric and thermal efficiency, evaluating through performance metrics two optimization methods. The inlet and exhaust valves timing were chosen as design variables. The multi-objective optimization methods used are Non-dominated Sorting Genetic Algorithm – II and Multi-Objective Differential Evolution. Simulations are performed for four different engine speeds. The compressible duct flow is numerically solved by the two step Lax-Wendroff method with Total Variation Diminishing flow control. The performance metrics used in this study are maximum values, number of non-dominated solutions, spacing, hyper-volume and time simulation. The results showed a Pareto front maximizing the volumetric efficiency and decreasing thermal efficiency, and vice versa. The Multi-Objective Differential Evolution presented greater values than Non-dominated Sorting Genetic Algorithm – II, more non-dominated solutions, higher hyper-volume values, with the advantage of spent less computational time. Both approaches were able to optimize internal combustion engine efficiencies finding the optimal valve timing sets. Moreover, allows finding conditions for opening and closing valves that favor both efficiencies.

Investigating the effect of the air inlet temperature on the combustion characteristics of a spark ignition engine fueled by biogas

AbstractThis work has conducted a numerical study using AVL‐Boost engine simulation utilizing biogas (CH4 and CO2)–air mixtures in a SI engine model. The effect of varying the air manifold temperature from 25 to 50°C on the combustion characteristics as well as engine performance under full load condition in a SI engine fueled by gasoline and biogas mixtures has been investigated. The performed tests involved using variable concentrations of CO2 from 10% to 40% by volume. The current model has been validated with experimental results and it was found that the error in predicting the P‐θ behavior of the engine is about 4.89%. The results showed that, as the air inlet temperature increases, the volumetric efficiency decreases and the brake specific fuel consumption (BSFC) increases for gasoline and all biogas compositions. However, the peak pressure, brake output power, maximum pressure rise rate, and maximum heat release rate were decreased slightly with the increase in air inlet temperature. The effect was only observed for gasoline and the 10%‐CO2 biogas, whereas the effect on the maximum heat release rate was detected on gasoline and biogas compositions up to 20%‐CO2 only. On the other hand, the existence and growth of CO2 content in the biogas reduced significantly the peak pressure, brake output power, maximum pressure rise rate, volumetric efficiency, and both net and maximum heat release rates, though its effect in reducing the volumetric efficiency stopped at 20%‐CO2 biogas. Furthermore, BSFC rises noticeably with the increase in CO2 ratio in biogas. © 2020 Society of Chemical Industry and John Wiley & Sons, Ltd.

Constraint-based parameterization using FFD and multi-objective design optimization of a hypersonic vehicle

Constraint-based parameterization is of vital importance to the airbreathing hypersonic vehicle due to the strong integration between the scramjet engine and the airframe. In the current study, an enhanced free-form deformation approach is proposed and utilized to parameterize the EXPERT geometric configuration with its prescribed constraints satisfied. Considering the boundary feature of the Bernstein basis function, the non-parallelepiped free-form deformation lattice is assigned quickly and modified automatically. The configuration is optimized by the nondominated sorting genetic algorithm II (NSGA II) coupled with the Kriging surrogate model. The maximum lift-to-drag ratio, the maximum volumetric efficiency and the minimum heating rate at the stagnation point are all taken as the objective functions in the optimization process. At last, the Pareto front is obtained, and the surrogate-based predicted results show reasonable agreement with the data obtained by the engineering approaches. Finally, some optimized configurations are reconstructed, and the preservation of the prescribed constraints is observed.

Intake pressure and brake mean effective pressure analysis on various intake manifold design

The internal combustion engine has an intake system that preparing sufficient charges for the engine cylinder. This study is focused on the effect of different intake geometry on the intake pressure and brake mean effective pressure to correlate volumetric efficiency and brake power performance. Five types of intake geometry are simulated by a one-dimensional computational tool. Through the simulations, it can be found the maximum volumetric efficiency predicted by taper design at 1.15 bar of intake pressure and 12.50 bar of brake mean effective pressure when volumetric efficiency reached to 115% and brake power of 19.5 kW. The baseline intake and bellmouth intake showing intake pressure at 0.91 bar and 0.94 bar except for both single bend intake and s-bend intake indicated 0.92 bar intake pressure and 9.35 bar of brake mean effective pressure. The measurement of intake pressure and brake mean effective pressure over various intake geometry displayed a significant influence on the volumetric efficiency and brake power trend.

Optimization of Suction Chamber Structure in a Scroll Refrigeration Compressor

In order to improve the suction performance of the scroll compressors, five modification models are proposed by reducing or enlarging the area of the suction flow passage based on a scroll refrigeration compressor. The three-dimensional numerical simulation model is established using the commercial software PumpLinx to calculate the flow field and the performance of every modified model. The comparison and analyses has been done based on the simulation results. The results indicated that the enlargement of the suction passage only improve the volumetric efficiency a little while the shrink of the suction passage can improve it effectively. The mass flow rate pulsation when the modification angle is 270° is much higher than that of the original model, but it decreases with the modification angle. As the modification angle increases, the volume of inner suction passage and the back flow rate from the inner suction passage decrease and less fluid from suction chamber 2 flows back to the suction port, so the average mass flow rate increases and the mass flow rate pulsation decreases. The Model 5 has the maximum volumetric efficiency and lower mass flow pulsation, but the tangential and radial forces on the orbiting scroll are the highest.

Performance improvement in opposed Piston Linear Compressor for household refrigerator by reducing clearance volume

An Oil-free Opposed Piston Linear Compressor (OPLC), driven by linear motor, is a promising technology for household refrigerators which works efficiently at resonant speed. These compressors with valve-less arrangement have been successfully used in Cryogenics applications for different Cryocoolers. In case of single piston linear compressor, the discharge is axial, and the piston can reach the cylinder walls, ideally giving zero clearance volume. The dual arrangement of piston and cylinder on both the sides with perpendicular discharge adds additional clearance volume resulting in poor volumetric efficiency. This article discusses the impact of clearance volume on OPLC performance and its volumetric efficiency. To increase the performance, clearance volume was reduced by modifying the design of OPLC. Maximum volumetric efficiency observed is 56% for clearance volume of 0.712 cc.

Deproteinated potato wastewater as a low-cost nitrogen substrate for very high yeast biomass quantities: starting point for scaled-up applications

The aim of this research was to investigate the influence of deproteinated potato wastewater (DPW) supplemented by different initial concentrations of glucose on biomass yield, especially lipids biosynthesis and fatty acids composition. DPW is a low-cost source of nitrogen and other biogenic elements. It allowed for an efficient yeast cells growth and a very high biomass yield of Rhodotorula glutinis var. rubescens LOCKR13. A short time of incubation leads to a biomass rich in protein, which can be a source of single-cell protein. The strain was able to accumulate 46% cell dry weight (CDW) of lipids in control medium and only 18% when DPW medium were used. The maximum volumetric lipids efficiency in the DPW medium was 6.14 g L−1. Oleic (41.0–51.5%), palmitic (15.3–17.8%), and stearic acids (5.8–7.5%) dominated the entire pool of fatty acids. Theoretical calculations indicated a possibility to use the methylated esters of lipids from R. glutinis var. rubescens yeast as a biodiesel.

Performance study on a single-screw compressor for a portable natural gas liquefaction process

Portable natural gas liquefaction devices are widely used to exploit unconventional natural gas resources and one of key components is a compressor. In this paper, a new natural gas liquefaction process is simulated and optimized and a single-screw compressor with 200 mm diameter is designed to be applied in this process. To verify the performance of the single-screw compressor, an experimental system was set up and performance parameters were studied, including volumetric efficiency, specific power rate, shaft efficiency, irreversible loss rate and cooling efficiency of the lubricating oil. The influence of the lubricating oil on the volumetric efficiency was also observed. Furthermore, the impact of actual compressor performance on the liquefaction process was also analyzed. The results indicate that the performance of the compressor changes greatly when it operates deviating from its design condition. The maximum volumetric efficiency, shaft efficiency, irreversible loss rate and cooling efficiency of the lubricating oil are 0.91, 0.64, 0.56 and 0.22, respectively. The minimum specific power rate is 6.5 kW·(m3·min−1)−1. In addition, the lubricating oil has a good effect of sealing so that the volumetric efficiency can be improved by 10.5%. Considering the actual performance of the single-screw compressor, specific power consumption of the process increases by 43.3%.

Influence of inlet pressure and rotational speed on the performance of high pressure single screw expander prototype

To recover high pressure energy in a letdown station, a high pressure single screw expander (HPSSE) with 117 mm diameter is developed in our laboratory recently. This study presents the results of an experimental survey on the performance of HPSSE under varied inlet pressure and rotational speed. The inlet pressure of HPSSE ranges from 1.0 MPa to 5.0 MPa and the rotational speed is from 1500 rpm to 3000 rpm. The experimental results show that when the inlet pressure is 5.0 MPa, the maximum power output, volumetric efficiency, isentropic efficiency and shaft efficiency of HPSSE are 56.55 kW, 80.57%, 62.55% and 50.96%, respectively. The volumetric efficiency is immensely affected by inlet pressure under fairly slow rotational speed and a slight change in volumetric efficiency is observed under considerably high rotational speed. A high rotational speed is an effective method to reduce leakage in large pressure difference working conditions.

Performance Study on a Single-Screw Expander for a Small-Scale Pressure Recovery System

A single-screw expander with 195 mm diameter is developed to recover pressure energy in letdown stations. An experiment system is established using compressed air as a working fluid instead of natural gas. Experiments are conducted via measurements for important parameters, such as inlet and outlet temperature and pressure, volume flow rate and power output. The influence of inlet pressure and rotational speed on the performance are also analyzed. Results indicate that the single-screw expander achieved good output characteristics, in which 2800 rpm is considered the best working speed. The maximum volumetric efficiency, isentropic efficiency, overall efficiency, and the lowest air-consumption are 51.1 kW, 83.5%, 66.4%, 62.2%, and 44.1 kg/(kW·h), respectively. If a single-screw expander is adopted in a pressure energy recovery system applied in a certain domestic natural gas letdown station, the isentropic efficiency of the single-screw expander and overall efficiency of the system are found to be 66.4% and 62.2%, respectively. Then the system performances are predicted, in which the lowest methane consumption is 27.3 kg/(kW·h). The installed capacity is estimated as 204.7 kW, and the annual power generation is 43.3 MWh. In the next stage, a pressure energy recovery demonstration project that recycles natural gas will be established within China, with the single-screw expander serving as the power machine.