Pumping Losses Research Articles

Effects of the continuous variable valve lift system and Miller cycle strategy on the performance behavior of the lean-burn natural gas spark ignition engine

In order to further improve thermal efficiency and fuel economy, the engine community pays more attention to the advanced controlling strategy. In this paper, the impacts of the continuous variable valve lift (CVVL) system and Miller cycle strategy on the performance behavior of the natural gas spark ignition (SI) engine were comprehensively investigated. The results indicated that pumping loss was decreased, and volumetric efficiency slightly increased with using CVVL. In addition, the intake air mass flow at the intake ports became more smooth, and turbulence flow and its intensity were strengthened with using CVVL, which were beneficial to accelerate combustion rate and improve combustion efficiency. Under the partial load of the 1200 rpm 5 bar, the ratio of the pumping mean effective pressure (PMEP) in indicated mean effective pressure (IMEP) was reduced by 2.74%. Furthermore, an extra 5.43% improvement of indicated thermal efficiency was obtained. On the other hand, peak in-cylinder pressure and peak combustion temperature of the natural gas SI engine operated on Miller cycle were decreased with late intake valve close (LIVC), particularly the pressure and temperature at the end of the compression stroke, which resulted in reducing NOx emissions formation and mitigating knocking combustion. However, the intake mass flow at the intake ports became fluctuation and the volumetric efficiency was decreased with using LIVC. In addition, brake specific fuel consumption was increased and indicated thermal efficiency decreased with employing LIVC.

A Case study of Exergy Losses of a Ground Heat Pump and Photovoltaic Cells System and Their Optimization

The aim of this scientific research is to experimentally determine the exergy losses of a ground heat pump and further optimization for more efficient use of operating modes and improvement of individual structural elements. In addition, it is proposed to use photovoltaic panels as a backup power source for the experimental installation under study. The exergetic losses are calculated, not only for the ground heat pump itself, with R407C refrigerant. The research methodology consists in a comprehensive assessment of exergetic flows, their optimization using new methods of approximation of piecewise linear functions, and the development of prerequisites for the use of anergy as one of the components of a new type of analysis of the efficiency of low-potential energy sources. As a result of processing the experimental data, the values of Coefficient of performance (COP) 4.136, exergetic temperature for the lower heat source 0.0253 and for the upper heat source 0.155, exergetic efficiency of the installation 0.62, and total loss of specific exergy of the heat pump 24.029 kJ/kg were obtained. Controllers with the Modbus protocol were used for data collection. Matlab Simulink was used to process the experimental data. When carrying out the procedure for optimizing the operating modes and selecting several modes with minimal exergetic losses, an important role is given to mathematical methods of processing statistical data. The method of increasing the efficiency of the heat pump is shown, first of all, based on the use of photovoltaic panels as a backup power source and optimization of exergetic losses due to exergo-anergetic evaluation of operating modes. The authors present the measurement errors of the heat pump plant parameters in the form of a 3D Gaussian curve, which becomes possible only when applying new approximation methods in the processing of measurements.

Theoretical and Experimental Investigation of the Performance of an Atkinson Cycle Engine

In this study, an Otto cycle engine was converted to the Atkinson cycle engine using the method of late intake valve closing and increasing the compression ratio. Firstly, the thermodynamic analysis was conducted. In the analysis, the variation of specific heats with temperature, heat losses, pumping, and mechanical friction losses was taken into account. In-cylinder pressure variations, torque, power, thermal efficiency and brake-specific fuel consumption variations with speed were obtained. For the experimental study, a new camshaft was designed and manufactured using a circular arc curve. The IVC timing of the Atkinson engine was delayed by a 20° crankshaft angle with respect to standard timing. The compression ratio was increased from 8.5 to 9.5. Tests were conducted at 1400–3400 rpm speed range at WOT. Experiments were conducted at three different operating conditions: Otto cycle for the standard engine, late closing of the intake valve at 20 ° CA at 8.5 compression ratio and late closing of the intake valve at 20 ° CA at 9.5 compression ratio. In the tests, the variation of torque, power, BSFC and thermal efficiency with speed were investigated. The results showed that torque, power, BSFC and thermal efficiency were improved with Atkinson CR9.5 operation compared to the standard Otto cycle operation at high speeds. It was obtained that the torque and power of the Atkinson CR9.5 cycle engine increased by 6.7% and the thermal efficiency increased by 12.8% at 3400 rpm speeds. In addition, BSFC of the Atkinson CR9.5 engine decreased by 12.7%.

An Empirical Model for the Churning Losses Prediction of Fluid Flow Analysis in Axial Piston Pumps.

The manufacturing development of axial piston pumps usually takes the trend of high speed and miniaturization, and increases power density. Axial piston pumps are usually characterized as high speed to improve the power density; thus, high-speed churning losses caused by the internal rotating components stirring the oil can increase significantly. In order to improve the efficiency, more attention should be given to the churning losses in axial piston pumps, especially in high-speed conditions. Using the method of least-squares curve fitting, this paper establishes a series of formulas based on the churning losses test rig over a wide range of speeds, which enable accurate predictions of churning losses on the cylinder block and pistons. The reduction coefficient of flow resistance of multi-pistons as calculated. The new churning losses formula devoted to the cylinder block and rotating pistons was validated by comparison with experimental evidence in different geometries of axial piston pumps. According to the prediction model of churning losses, some valuable guidance methods are proposed to reduce the energy losses of the axial piston pump, which are the theoretical support for the miniaturization of axial piston pump manufacturing.

Numerical Simulation to Investigate the Occurrence of Vortices at Double Vertical Pumps Intakes

The pumping station is widely used in our modern life. The occurrence of the vortex at pumpsump, which is causing air entering pipe intake, is a common problem in the design of pumps. Thisphenomenon, including surface and sub-surface vortex, may lead to damage to the pumping structure, highpower consumption, and loss in pump performance. In some requirements, the multiple suction pipes areusing to get the required flow. Due to this arrangement, the performance of the suction pipes will influence.This paper is aimed to investigate the occurrence of vortices around the flow pattern of two pumps by usingComputational Fluid Dynamic (CFD) code Fluent. This CFD model is based on solving Navier-Stockequations by finite volume method. The model of double suction pipes was investigated under five differentsubmergence depth (S) and five different suction velocities (v). The SST k-ω turbulence model was selectedfor the turbulence. The results showed that the air entering vortex does not appear when the submergencedepth (S) is equal or greater than 1.5 times from the diameter of the bellmouth for intake pipe (D). Thesurface vortex appeared obviously when the submergence depth (S) equals to 1.25D and the Froude numberat the bell is equal to or greater than 1.028, and appeared clearly when the (S/D=1) and Froude number isequal to or more than 0.77. The nearer attached wall vortex does not appear when the space from the centerof the suction pipe to the sidewall (C) equals 2 times of bell diameter.

Impact of Active Control Turbocharging on the Fuel Economy and Emissions of a Light-Duty Reactivity Controlled Compression Ignition Engine: A Simulation Study

While forced induction strategies such as turbocharging can increase the power output and extend the load limit of engines operating on low temperature combustion strategies such as reactivity controlled compression ignition, the low exhaust enthalpy prevalent in these strategies requires the use of high backpressures to attain high turbocharger efficiencies, leading to high pumping losses and in turn poor fuel economy. Hence, there is a need to improve the exhaust energy utilization by the turbocharger such that the negative effects of the high backpressure requirements are offset. One turbocharger operating strategy that has the potential to enhance exhaust enthalpy conversion by the turbine is active control turbocharging (ACT), in which the rack position of a variable geometry turbocharger (VGT) is actuated using a continuously varying sinusoidal signal whose frequency is proportional to engine speed. In this study, the impact of ACT on turbocharger performance and fuel economy of a light-duty reactivity controlled compression ignition engine equipped with a VGT is investigated through coupled GT-POWER/KIVA-3V simulations at a medium-load cruise operating condition. A design of experiments study was executed in which the rack position amplitude and phase angle were independently varied, and the turbine efficiency, compressor efficiency, crankshaft torque, and brake specific fuel consumption were tracked for each run. The results show that ACT operation significantly increased the torque output while improving fuel economy over baseline VGT operation, but the range of actuation signal amplitude ratio was limited to 40% of the maximum amplitude possible due to peak cylinder pressure and peak pressure rise rate constraints. It is also shown that the impact of signal phase angle on turbocharger efficiency and overall system performance is not as significant as the amplitude ratio. The best fuel economy improvement over the baseline VGT operation at cruise conditions was observed at 40% amplitude ratio and 0° phase angle, and this value was 2.8%.

Experimental and modeling analysis on the optimization of combined VVT and EGR strategies in turbocharged direct-injection gasoline engines with VNT

The combination of a growing number of complex technologies in internal combustion engines (ICE) is commonplace, due to the need of complying with the tight pollutant regulations and achieving high efficiencies. Hence the work of calibration engineers is led by a constant increase in degrees of freedom in ICE design. In this research work, a wide analysis on the optimization of combined variable valve timing (VVT) and exhaust gases recirculation (EGR) strategies is developed, in order to reduce fuel consumption in a EURO 6 1.3l 4-stroke 4-cylinder, gasoline, turbocharged, direct-injection engine, also equipped with a variable nozzle turbine (VNT). For that purpose, a methodology which combines 1D engine simulations with limited experimental work was applied. First, the data from 25 experimental tests distributed into three steady engine operating conditions was used to calibrate a 1D model. Then, modeling parametric studies were performed to optimize VVT and EGR parameters. A total of 150 cases were simulated for each operating point, in which VVT settings and EGR rate were varied at iso-air mass flow and iso-intake manifold temperature. The optimization was based on finding the configuration of VVT and EGR systems which maximizes the indicated efficiency. All different cases modeled were also evaluated in terms of pumping and heat losses. Moreover, a deep assessment of instantaneous pressure traces and mass flows in intake and exhaust valves was given, to provide insights about the optimization procedure. Finally, the findings obtained by simulation were compared with the results from a design of experiments (DOE) composed of more than 300 tests, and the impact on engine fuel consumption was analyzed.

Experimental investigation of the effects of Miller timing on performance, energy and exergy characteristics of two-stage turbocharged marine diesel engine

In order to analyze and improve the thermodynamic process of marine diesel engines and improve energy efficiency, the experimental study of the influence of Miller timing on the performance, energy and exergy of marine diesel engines was realized by redesigning the camshaft and adjusting the two-stage turbocharging system. The research results shown that with the increase of Miller timing, the average pumping loss decreased, the peak HRR and the maximum combustion temperature decreased, and the crank angle corresponding to the peak HRR was delayed backward, resulting in a backward delay of the 50% point, the 10–90% combustion duration was extended, and the EER, EEE and BTE first increased and then decreased. Secondly, the Miller cycle combined with two-stage turbocharging could make marine diesel engines reduced NOx emissions by more than 25% with a small effect on the BSFC. In addition, as the Miller timing increased, the proportion of exhaust energy, heat transfer energy to coolant, mechanical loss, and combustion loss all decreased, while the proportion of brake output work first increased and then decreased. The change trends of exergy terms with load and Miller timing were similar to their corresponding energy. It was worth noting that the exhaust exergy accounted for about 40% of the exhaust energy, while the heat transfer exergy to coolant accounted for only 13% of the heat transfer energy to coolant, indicating that the exhaust energy quality was higher, the utilization potential was greater, and the efficient utilization interval was concentrated in the high load area.

Study on energy loss of 35 kW all vanadium redox flow battery energy storage system under closed-loop flow strategy

A large all vanadium redox flow battery energy storage system with rated power of 35 kW is built. The flow rate of the system is adjusted by changing the frequency of the AC pump, the energy efficiency, resistance, capacity loss and energy loss of the stack and under each flow rate is analyzed. The energy efficiency of the system is calculated by combining with the pump loss. The results show that with the increase of flow rate, the energy efficiency of the stack is improved and the stack resistance is reduced, but pump loss increases greatly. At 180 mA•cm−2 current density and 110 L/min flow rate, the energy efficiency of the stack reached 77.10% and the system reached 69.49%. In the battery system, the loss of resistance energy accounted for 80.27% of the total energy consumption, and the pipeline and transfer energy loss accounted for 18.73%. Therefore, reducing the energy consumption of the pump and reducing the energy loss of the resistance in the system are very important for improving the energy efficiency of the all vanadium redox flow battery energy storage system.

Blocked serpentine flow field with enhanced species transport and improved flow distribution for vanadium redox flow battery

A blocked serpentine flow field is proposed for vanadium redox flow battery (VRFB) in order to improve electrolyte penetration and convection in the porous electrode such that the overall battery performance can be boosted. A three-dimensional mathematical model with considering non-uniform electrode structure under compression and electrode intrusion into channels was applied for simulating and comparing the VRFB performance with conventional serpentine flow field and blocked serpentine flow field. It was indicated that for blocked serpentine flow field, with increasing the block height from 0 mm to 1.5 mm, the discharge voltage of the battery is obviously boosted due to the enhanced species transport and improved flow distribution in the porous electrode. Also, it was shown that the overall battery performance in terms of net discharge power and system efficiency reaches maximum for the blocked serpentine flow field with 1.4 mm block height among different flow field designs, which is attributed to the tradeoff between the effects of increased pump loss and the improved charge-discharge performance. This study can provide beneficial advice for designing the suitable flow field for VRFB with improved mass transport performance.

Design Analysis and performance evaluation of 3D printed baffle path diverters in hydraulic noise suppressor

The pump in the hydraulic systems is the main source of noise in form of vibrations or pulsations while noise reduction is an important part of pump design still some ripples are produced by the pump termed as pulsations. Pulsations result in line vibrations which cause additional noise. How much ripple the pump produces cannot be changed, so other ways to an average of 50 dB(A) to 60 dB(A) level of noise is often considered to safe, although the noise levels resulting due to pulsations are seen to be in ranges as high as 130 t 0 150 dB(A) that result in hose and piping failures and also results in damage to components like seals and valves. Through the introduction of a compressible membrane in the path with additional baffles for muffling of the noise the proposed solution is in the form of hydraulic noise reducer that incorporates both the compressible membrane as well as the baffle path diverter. Objective of paper is carried out the performance evaluation of the hydraulic noise reducer with elastomer membrane for noise reduction mechanism in conjunction to baffle type path diverters to even out the fluid pulsations or ripple to minimal without much pressure drop across the device to achieve minim; pumping losses. The paper discusses the performance evaluation of the diverter. The has been tested to determine mass flow rate and pressure drop. Experimental has been manufactured and test has been conducted to evaluate reduction in noiselevelinwithandwithoutthe3-dprintedbaffle arrangement and comparison has been carried out.

Effect of front impeller seal leakages on centrifugal stage characteristics

One of the main criteria in designing a pump unit is its economic efficiency and reliability. The efficiency of the pump is impacted by losses which appear in the pump and can be classified into three categories: hydraulic, mechanical and volumetric. Volumetric losses in centrifugal pumps appear in impeller annular seals and throttling gaps of hydraulic balancing devices. Decreasing clearance in annular seals could, undoubtedly, reduce the volumetric losses and lead to an increase in pumps efficiency. In duties close to optimal, a volume of leakages is almost negligible for the main flow passing through the hydraulic passage. On the contrary, impact of leakages becomes significant at underloaded duties. This article deals with effect of leakages in impeller front seal on efficiency and head-capacity curve.

Numerical Study of the Performance Loss of A Centrifugal Pump Carrying Emulsion

The performance and hydrodynamic behavior of centrifugal pumps when handling two-phase liquid-liquid flow and emulsion remain relatively unexplored, although they are of fundamental importance in optimizing the operating conditions of these pumps. Hence, this study aims at investigating the performance degradation of a centrifugal pump under emulsion flow by combined means of analytical and computational fluid dynamic (CFD) models. The analytical approach is based on internal energy loss equations while the CFD approach models the emulsion as a continuous and homogeneous single-phase fluid exhibiting shear thinning behavior. The results give a good insight into the performance degradation of such a system, especially at the best efficiency point (BEP).

Progressive familial CD10 deficient ductopenic disorder; Hitherto an unnamed entity! - A case report

Inherited liver disorders are group of genetic diseases that cause early liver involvement many of them progressing to early cirrhosis. Of the familial cholestatic disorders most widely studied are progressive familial intrahepatic cholestatic disorders. These disorders are caused by defects in enzymes involved with the formation and excretion of bile constituents. They are, however, not associated with ductopenia. We herein report the first case of a familial cholestatic disorder in three female siblings resident of Lahore, Pakistan presenting as chronic cholestasis all progressing to cirrhosis before 10 years of age. The first two female siblings underwent liver transplants for chronic cholestasis. The third sibling underwent liver biopsy for the evaluation of cholestasis and later liver transplant for same. There are no other associated cardiac or skeletal anomalies in any of the sisters. The findings of biopsy and explant tissue were similar in all three sibling sisters. There are features of advanced fibrosis, significant ductopenia, bile ductular reaction at the porto-parenchymal interface, cholestasis, increased copper stores on rhodanine stain no loss of bile salt export pump, and multi-drug resistant 3 protein (MDR3), and the absence of CD10 from canaliculi. The findings raised differentials for progressive familial intrahepatic cholestasis (PFIC) type 3, Alagille syndrome, and variant of familial cholestatic disorder. PFIC 3 causes cholestasis, but the presence of MDR3 stain, ductopenia, and deficient CD10 are not seen in PFIC 3. Familial ductopenic disorders have been identified in the adult population called as idiopathic adulthood ductopenia and had autosomal dominant pattern of inheritance. The argument against Alagille syndrome is the absence of any other syndromic features of Alagille and autosomal recessive mode of inheritance. These findings led us to conclude if there is a need to redefine a new entity of progressive familial CD10 deficient ductopenic disorder. The findings though limited by genetic studies give way for further research on the subject.

High-quality laser wakefield electron accelerator

The acceleration gradient of laser wakefield acceleration is 3–4 orders of magnitude higher than that of state-of-the-art radio-frequency accelerators, which has unique advantages in the field of electron acceleration. With the development of application fields, higher requirements are put forward for the quality of electron beams. Achieving high stability, high energy, high charge, narrow pulse width and low emittance is the direction of long-term efforts in the field of electron acceleration. This article mainly summarizes the achievements of the relevant research teams in electron acceleration from Shanghai Institute of Optics and Fine Mechanics in recent years. The energy of the electron beam based on the acceleration of the laser wakefield is mainly limited by the dephasing length and the laser pumping loss length. Aiming at the problem that the two stages of laser wakefield acceleration cannot be controlled independently and the plasma density is difficult to balance, a cascaded acceleration scheme where the injection stage and the acceleration stage are separated is proposed. The injection stage has a higher plasma density and the acceleration stage has a lower plasma density. The acceleration stage with lower density has a longer dephasing length, so that a higher acceleration can be obtained without affecting electron injection. Finally, the electron beam energy of the order of GeV is obtained in experiment. In order to obtain a higher-quality electron beam, a low-energy-spread electron beam is obtained experimentally by using energy chirp controlling. The six-dimensional phase space brightness, which simultaneously characterizes multiple qualities such as electron beam emittance, charge and pulse width, is introduced. It is hard, with high quality only, to achieve long-distance transmission of electron beams and to generate free electron lasers. For the development of free electron lasers, the transmission and modulation of the electron beam are equally important. Taking into account the need to further optimize the acceleration of electrons from generation to realization of active control, higher quality and higher stability, it is necessary to monitor the interaction process between laser and plasma in time to obtain parameter through diagnosis. We have designed and optimized a variety of diagnostic solutions suitable for electron acceleration in the laser wakefield to achieve single-shot measurement of electron beams at different positions, such as using Betatron radiation inversion to measure ultra-low emittance. The effect of laser multifilament on the quality of the generated electron beam is also discussed.

Exploring the synergies of dynamic fuel management and propulsion electrification

Active fuel management is a technology that allows a multi-cylinder internal combustion engine to shut off a bank of cylinders to reduce engine power output as needed to match driving conditions and driver power demand. This variation in engine power is taken a step further with a technology known as dynamic fuel management, wherein individual cylinders of a multi-cylinder engine may be turned off as needed. This approach allows a finer resolution in engine power variation. Dynamic fuel management allows an engine to operate with lower pumping losses, thereby maximising the potential for capturing regenerative braking energy. In this paper, the synergies of such an engine equipped with dynamic fuel management, coupled to an electrified driveline incorporating a 48V P1 architecture, are investigated. Detailed MATLAB models are developed to understand the influence of system parameters as well as to identify the optimal engine/motor torque arbitration required for maximum fuel economy. It is shown that the combination of dynamic fuel management and P1 hybridisation can provide a substantial fuel economy improvement.

Exploring the synergies of dynamic fuel management and propulsion electrification

Active fuel management is a technology that allows a multi-cylinder internal combustion engine to shut off a bank of cylinders to reduce engine power output as needed to match driving conditions and driver power demand. This variation in engine power is taken a step further with a technology known as dynamic fuel management, wherein individual cylinders of a multi-cylinder engine may be turned off as needed. This approach allows a finer resolution in engine power variation. Dynamic fuel management allows an engine to operate with lower pumping losses, thereby maximising the potential for capturing regenerative braking energy. In this paper, the synergies of such an engine equipped with dynamic fuel management, coupled to an electrified driveline incorporating a 48V P1 architecture, are investigated. Detailed MATLAB models are developed to understand the influence of system parameters as well as to identify the optimal engine/motor torque arbitration required for maximum fuel economy. It is shown that the combination of dynamic fuel management and P1 hybridisation can provide a substantial fuel economy improvement.

Development of a new mechanical electro hydraulic valvetrain system

Variable valve actuation (VVA) technologies can provide improvements in fuel economy of spark-ignition (SI) engines by shifting valve timings or generating valve profiles that can minimize pumping loss. Electro hydraulic valve (EHV) is one of VVA technologies that is highly flexible in producing valve profiles to control charge mass without throttle. In this work, a new EHV which has a unique operating mode, namely mechanical mode, is introduced. The mechanical mode enables operation of valvetrain under circumstances of EHV malfunctions: the mechanical electro-hydraulic valvetrain (MEHV) developed in this study was capable of stable operation under various operating modes at wide ranges of oil temperatures and cam speeds with appropriate valve seating velocity and ramp duration. The MEHV is a VVA technology that can resolve issues of previous EHVs which lacked reliability under emergency conditions.

Study on characteristics of vortex structures and irreversible losses in the centrifugal pump

The development of flow control methods in the centrifugal pump relies on further understanding of the characteristics of vortex structures and their irreversible losses. In this paper, the detached eddy simulation is conducted on a model centrifugal pump, which shows a good agreement with the experiment. Combining with three generations of vortex identification methods (vorticity, Q criterion, omega and Liutex methods) and entropy production analysis, the results show omega and Liutex methods are highly recommended to analyze the vortex structures. Vorticity is the key factor to promote the energy dissipation, and the irreversible losses of vortex areas can be lower than their surroundings when there exists smaller vorticity or higher rotation strength. Concerning the pressure pulsation induced by vortex shedding, it is unreasonable to analyze this unsteady process via vortex structures identified by iso-surface because of the restriction of the threshold. In comparison, the change of integral length is more related to the pressure pulsation.

Simultaneous control of NOx, soot and fuel economy of a diesel engine with dual-loop EGR and VNT using economic MPC

This paper proposes a nonlinear Economic Model Predictive Control (eMPC) strategy for the airpath management of diesel engines with dual-loop Exhaust Gas Recirculation (EGR) and Variable Nozzle Turbocharger (VNT). The controller directly controls the VNT and dual-loop EGR valves to simultaneously minimise NOx, soot and pumping loss. The novelty of this management strategy is to use a merged controller to replace a conventional combination of supervisory and tracking controllers, as well as eliminating the offline determination of the intake manifold pressure and cylinder oxygen concentration set points. The eMPC computes the set points online based on the engine operating condition, state feedback and the weightings of each economic objective, namely NOx, soot and fuel economy. The eMPC is simulated with an experimentally validated EURO 6 2L four-cylinder engine model. The performance of the eMPC is compared to a production controller over the Worldwide harmonised Light vehicles Test Cycles (WLTC). Compared to the production controller, the eMPC demonstrates NOx and soot emission reductions as well as improved torque tracking and fuel economy.