Piston Valve Research Articles

Investigations of the Friction Losses of Different Engine Concepts. Part 1: A Combined Approach for Applying Subassembly-Resolved Friction Loss Analysis on a Modern Passenger-Car Diesel Engine

This work presents the application of a combined approach to investigate the friction losses in a modern four-cylinder passenger-car diesel engine. The approach connects the results from engine friction measurements using the indication method and the results from journal-bearing simulations. The utilization of the method enables a subassembly-resolved friction loss analysis that yields the losses of the piston group, crankshaft journal bearings, and valve train (including the timing drive and crankshaft seals). The engine and engine subassembly friction losses are investigated over the full speed and load range, covering more than 120 engine operation points at different engine media supply temperatures ranging from 70 to 110 ∘ C. The subsequently decreasing lubricant viscosity due to higher engine media supply temperatures allow for the identification of friction reduction potentials as well as possible risks due to an onset of mixed lubrication. Furthermore, additional strip-tests have been conducted to determine the friction losses of the crankshaft radial lip seals, the timing drive, and the crankshaft journal bearings, thus enabling a verification of the calculated journal-bearing friction losses with measurement results. For the investigated diesel engine, a friction reduction potential of up to 21% could be determined when increasing the engine media supply temperature from 70 to 110 ∘ C, at engine speeds higher than n = 1500 rpm and part load operating conditions. At low engine speeds and high load operations, the friction loss reduction potential is considerably decreased and below 8%, indicating mixed lubrication regimes at the piston group and valve train.

Experimental Investigation on Lemongrass Oil Water Emulsion in Low Heat Rejection Direct Ignition Diesel Engine

Abstract This article discusses the experimental investigation of a new biofuel (lemongrass oil) feedstock as an alternative fuel. The subject has not drawn much attention among the fraternity of researchers. So far, an exploration for a new biofuel feedstock has resulted in demonstrating lemongrass oil (LGO) as an alternative energy source. Nickel-chromium-zirconium coating on piston, inlet, and exhaust valves is achieved using a plasma spray method. The coated engine has been tested with a constant level of neat diesel and varying proportions of 5, 10, and 15 percent of LGO–water emulsion; its properties have been analyzed per the ASTM standards. The considered test fuel was experimentally investigated in a single cylinder diesel engine at 1,500 rpm for its performance, combustion, and emission characteristics. Among the different mixtures, a fuel mixture of LGWM1 (LGO of 94 %, water of 5 %, span 80 of 0.5 %, and tween 80 of 0.5 %) profile had similar properties to diesel fuel, resulting in a higher thermal efficiency and a lower hydrocarbon, carbon monoxide emission. However, oxides of nitrogen and carbon dioxide emission were comparatively higher for the test fuel considered. The cylinder pressure and heat release rate curves show a slight increase at the full load condition as compared with diesel fuel. Against the background of continuous fossil fuel depletion, the fuel blend of LGWM1 (LGO of 94 %, water of 5 %, span 80 of 0.5 % and tween 80 of 0.5 %) acts as a promising alternative fuel for further research work.

The Investigation of Geometric Parameters on the Injection Characteristic of the High Pressure Common-Rail Injector

According the actual structure and working principle of a fuel injector to build a model of the common-rail injector, including the control valve, the solenoid valve, and the needle valve of the injector. The model includes the leakage model for the control piston and needle valve that takes into account increasing leakage at high pressure. The performance of the fuel injector is investigated using a one-dimensional numerical model. Analyzing the effect of the system and structure parameters including common-rail pressure, injection pulse width, inlet and outlet hole diameter, and the injection nozzle on the injection characteristics of the fuel injector. Results show that the geometric parameter is the main property affecting the flow characteristic of the injector, which includes the flow rate of inlet and outlet hole, pressure waves in the control chamber and injection rate. The common-rail pressure, injection pulse width and the geometric parameters mainly affect the injection performance, such as the injection rate and injected volume. The investigation result can provide some useful information to improve the injection characteristic in follow-up studies.

An integrated and automated calibration system for pneumatic piston gauges

Recently, a transducer-aided crossfloat (TAC) method for pneumatic piston gauges was proposed. The concept is to use a pressure transducer as a very short-term transfer standard between the standard piston gauge and the test one. Different from the traditional method, a near-perfect balance condition is no longer required and the trim mass adjustment can be avoided. Here we present the detailed studies of the TAC method including the effects of the dead volume of the transducer line, the deviation from the balance condition, and the transducer resolution parameter. Based on the TAC method, an integrated and automated calibration system was designed and developed, which incorporates the manifold and the software. Two high-resolution pressure transducers with the range of 1.4–14 MPa are used to cover the wide calibration range from 10 kPa to 7 MPa. The automated system has the functions of pressure and piston position control, valve operation, and data acquisition.

Investigation of the effects of pre-heated linseed oil on performance and exhaust emission at a coated diesel engine

Abstract In this study, the efficiency of using the linseed oil, one of the vegetable oils, in a diesel engine by applying pre-heating was investigated. For this purpose, the pure linseed oil was mixed with diesel fuel at volumetric rates of 30% and 50% and this mixed fuels was used in a four-stroke, single-cylinder, and air-cooled diesel engine. In order to improve the combustion efficiency and reduce the loss of energy of the diesel engine, the parts of the combustion chamber (piston, exhaust, and inlet valves) were coated at a thickness of 300 μm with Cr3C2, which is a ceramic material having a low thermal conductivity and resisting to high operating temperatures. Plasma spray method was used as the coating method. It was determined that the pre-heating process reduced the viscosity of the linseed oil and also provided a more favorable fuel flow and the coating process had a positive effect on diesel emissions (CO, HC, Smoke, Exhaust Gas Temperature, Brake Thermal Efficiency) of poor quality oils, however pre-heating and coating processes increased the NOx emission.

Energy and exergy analysis of reciprocating natural gas expansion engine based on valve configurations

Natural gas pressure should be reduced in city gate stations before consuming. Part of the physical exergy of this high pressure gas is wasted if throttling valves are employed for pressure reduction. Reciprocating natural gas expansion engine (RNGEE) could be utilized to recover most of the physical exergy. In this study, a single acting RNGEE is investigated thermodynamically in order to optimize the ports opening/closing times. For this purpose, cylinder and slide valves and two types of piston valves have been modeled and compared. Based on an exergy analysis, a genetic algorithm has been developed to optimize the valves timing. Moreover, effects of the pressure ratio on the exergetic efficiency and power generation of the RNGEE have been studied numerically. Methane was modeled as a real gas by employing AGA8 equation of state. Results showed that beside importance of exergy efficiency optimization, inlet process period has also critical impacts on engine performance. Moreover, power generation is almost the same while using cylinder or flange valves (∼1986 kW/kg) with exergy efficiencies of 83.6% and 82.7% respectively. In contrast, slide and piston valves are found to have lower power generation (1746 kW/kg and 1753 kW/kg respectively) with the exergy efficiency of ∼72%.

A general model to evaluate mechanical losses and auxiliary energy consumption in reciprocating internal combustion engines

Abstract The increasingly stringent emissions regulations and the climatic change as consequence of green house gases emissions have moved the research interest towards the optimization of the internal combustion engine. Hence, the reduction of the energy losses of the engine sub-systems like friction and parasitic energy consumption are of especial interest. In this work, a model to determine the friction losses and the engine accessories energy consumption is developed based on parameters obtained in standard test benches. A description of the models to estimate friction in the piston assembly, bearings and valve train, and energy consumption of the coolant, oil and fuel pump is provided. Finally, a brief application to demonstrate the model potential in diagnosis and predictive applications is discussed.

Influence of valve's lag characteristic on pressure pulsation and performance of reciprocating multiphase pump

Reciprocating multiphase pump is the key equipment for the oil-gas transport technology in the petroleum industry. The opening and closing motions of suction and discharge valves directly affect the transport performance and stability of pump. In this paper, the whole working cycle of reciprocating multiphase pump is studied by using computational fluid dynamics (CFD) method. The combined actions of piston, suction and discharge valves are dealt with User Defined Functions and dynamic grid technique. Based on the instantaneous motions of valves, the lag characteristics of suction and discharge valves under different working conditions are analyzed. And the influences of lag angles on the pressure pulsation, P-V diagram and input power of the pump are further investigated. The results show that the lag angles have a significant impact on the internal and external characteristics of the reciprocating multiphase pump. Due to the most obvious opening lag angle of discharge valve, the pump pressures and P-V diagram have the sudden fluctuations just after the end of compression process, which appear in the range of θ = 240.7°–273.1° for the initial condition. The gas volume fraction (GVF) plays more important role than the suction and discharge pressures in the working of reciprocating multiphase pump, and the opening lag angles of suction and discharge valves at GVF = 0.9 increase to more than 6 times at GVF = 0.1. By the comparisons of input power, the simulated results for reciprocating multiphase pump show good agreement with the results of prototype test. This study would provide a theoretical basis for the design of high-efficiency multiphase pump and valve.

Control Unit for a Coreless Stator for use with SI Engine Stepping Valve

Engine efficiency could be increased if valve timing could change with engine revolutions per minute. Poppet valves are fitted with strong springs which return them to their rest positions after being pushed down by cam lobes. Overcoming the spring loaded camshaft drive train requires a lot of engine power. Valve lift, lift duration and phase cannot be adapted with cam lobes on the camshaft but electromagnetic actuators or hydraulic/pneumatic phasing mechanisms could achieve change of lift duration and phase change. Stepping valves with flexible valve event software control, move perpendicular to the piston, thus avoiding piston valve collision problem. Engine cranking requiring fuel, spark and valve event can be done electronically without engine turning. The design of a control unit for an axial coreless stator to control the motion of the stepping valve through the Otto cycle positions intake, exhaust and power / compression is presented with successful simulation of the control algorithm. A 3phase, 12V coil prototype stator with 4 coils per phase, connected in series and consuming 3A from a 12V car battery has been prototypically realized. The project aims at essential processes to run the engine as fuel, air, spark all being software controlled, leading to a more efficient, environmentally friendly, reliable and powerful engine.

Investigation of the effect of FeCl 3 on combustion and emission of diesel engine with thermal barrier coating

Abstract In the present investigation, the engine performance and emission characteristics of a single cylinder diesel engine with yttria stabilized zirconia (YSZ) coating on piston crown and valves were studied. The 0.2 g L−1 of ferric chloride (FeCl3) as catalyst was added into the diesel fuel in both coated and uncoated engines. The results indicated that FeCl3 with diesel in a YSZ coated engine increased the brake thermal efficiency by 2.7%, and reduced brake specific fuel consumption by 8.3% as compared to standard diesel mode in uncoated engine. The selected thermal barrier coating improved the combustion in afterburning stage leading to effective use of intake air. Emissions such as carbon monoxide, hydrocarbons and smoke opacity were reduced with an increase in emissions of nitrogen oxide and carbon dioxide.

Outgas analysis of mechanical cryocoolers for long lifetime

Mechanical cryocoolers for space applications are required to have high reliability to achieve long-term operation in orbit. ASTRO-H (Hitomi), the 6th Japanese X-ray astronomy mission, has a major scientific instrument onboard—the Soft X-ray Spectrometer (SXS) with several 20K-class two-stage Stirling (2ST) coolers and a 4K-class Joule Thomson (JT) cooler, which must operate for 3 years to ensure the lifetime of liquid helium as a cryogen for cooling of its detectors [1,2]. Other astronomical missions such as SPICA [3,4], LiteBIRD [5], and Athena [6] also have top requirements for these mechanical cryocoolers, including a 1K-class JT cooler to be operated for more than 3–5 years with no cryogen system.The reliability and lifetime of mechanical cryocoolers are generally understood to depend on (1) mechanical wear of the piston seal and valve seal, and (2) He working gas contaminated by impurity outgases, mainly H2O and CO2 released from the materials in the components of the cryocoolers. The second factor could be critical relative to causing blockage in the JT heat exchanger plumbing and the JT orifice or resulting in blockage in the Stirling regenerator and thereby degrading its performance. Thus, reducing the potential for outgassing in the cryocooler design and fabrication process, and predicting the total amount of outgases in the cryocooler are very important to ensure cryocooler lifetime and cooling performance in orbit.This paper investigates the outgas analysis of the 2ST and the 1K/4K-JT coolers for achieving a long lifetime. First, gas analysis was conducted for the materials and components of the mechanical cryocoolers, focusing on non-metallic materials as impurity gas sources. Then gas analysis of the mechanical wear effect of the piston seal materials and linear ball bearings was investigated. Finally, outgassing from a fully assembled cryocooler was measured to evaluate whether the outgas reduction process works properly to meet the requirement levels.

The impact of running-in on the friction of an automotive gasoline engine and in particular on its piston assembly and valve train

Generally, mating surfaces that are in tribological contact undergo a running-in process at the beginning of their operational lifetime. During this running-in phase, the tribological operating condition changes significantly leading ideally to long-term operation with a minimum of continuous wear. While this process and its duration are rather well understood for single machine elements like journal bearings, it is the aim of this work to investigate the running-in behaviour of more complex systems like an internal combustion engine and its sub-assemblies. To gain insight into the influence and duration of this running-in phase, a series of tests have been performed under realistic engine operating conditions. To be able to separate the running-in processes for the individual subsystems’ piston assembly, valve train and journal bearings of the crank train, a large series of tests have been conducted for a conventional gasoline passenger car engine. The results show a strong influence of the running-in process on total engine friction, which can be attributed mostly to the direct acting valve train and to a considerably lesser extent to the piston assembly.

Impact of Oxidation Inhibitors on Performance and Emission Characteristics of a Low Heat Rejection Engine

In this study, for the first time analysis of a low heat rejection engine was carried out along with the addition of oxidation inhibitors. If the combustion chamber components of the engine such as piston, cylinder head, and inlet and outlet valves are insulated with a thermal barrier material, then the engine will be referred as low heat rejection engine. In this study yttria stabilized zirconia was coated on the combustion chamber components for a thickness of about 150 microns. Then the analysis of performance parameters such as brake thermal efficiency and specific fuel consumption and emission characteristics such as emission of carbon monoxide, hydrocarbon and nitrogen oxide was carried out in single cylinder four stroke diesel engine with electrical loading using diesel and pongamia methyl ester as the fuels. The major problem associated with the usage of biodiesels and low heat rejection engine is the increased NOX emission than the normal engine operated with the diesel. This problem has been overcome by the usage of oxidation inhibitors such as ethyl hexyl nitrate (EHN), tert-butyl hydroquinone (TBHQ). The results showed that addition of oxidation inhibitors leads to increase in brake thermal efficiency, reduced specific fuel consumption and reduced NOX emission.

3D CAD Modelling and Computational Fluid Analysis of Piston Valve of Twin Tube Shock Absorbers

This study aims to generate a 3D CAD model of the piston valve and conduct CFD analysis of the same. The piston valve of the shock absorber is one of the more critical parts of the mechanism assembly as the motion of the piston through the fluid in the working chamber of the damper is the primary source of damping force in suspension systems. The design of the piston valve is reverse engineered from existing designs and modelling is done in CREO 2.0 using cloud point data generated using Coordinate Measuring Machine. Computational fluid analysis is done using FLUENT integrated into ANSYS15.0 Workbench.

Characterization and Effect of Using Peanut Seed Oil Methyl Ester as a Fuel in a Low Heat Rejection Diesel Engine

To decrease hazardous emissions of internal combustion engines and to improve the combustion and thermal efficiency, thermal barrier coatings were applied. In this experimental study, cylinder, piston, exhaust, and inlet valves, which are combustion chamber components, were coated with a ceramic material and this enabled the engine to gain a low heat rejection feature. Cylinder, exhaust, and inlet valves of the diesel engine used in the tests were coated with ekabor-2 commercial powder, which is a ceramic material, to a thickness of 50 μm using the boronizing method. The piston of a diesel engine was coated in 300 μm thickness with bor-based powder using the plasma-coating method. Peanut seed oil methyl ester (PSME) was produced using the transesterification method. In addition, diethyl ether additive materials were used to improve the properties of diesel fuel, PSME, and its mixture. Diethyl ether was blended with test fuels, which were used as a pilot fuel, at the volumetric ratios of 4 and 8%. As a result of the thermal barrier coating, the brake-specific fuel consumption, carbon monoxide, hydrocarbon, and smoke density values of the diesel engine decreased, whereas nitrogen oxides, carbon dioxide, thermal efficiency, and exhaust gas temperature increased.

Modeling analysis of chrome carbide (Cr3C2) coating on parts of combustion chamber of a SI engine

In this study; piston, exhaust, and input valves of a gasoline engine were coated in 300 μm thickness with Cr3C2 by using the plasma spray coating method. The performance and emission values obtained from coated and uncoated engines were loaded on Artificial Neural Network (ANN) and estimated values were produced for every speed. Thus mathematical modeling of coated and uncoated (standard) engines was performed by using ANN. It was aimed to reduce the experiment repetitions and to decrease the experiment costs. The results obtained from the experiments were loaded on ANN and the values of the engines at all speeds were estimated. Results obtained from the tests were compared with those obtained from ANN and they were observed to be compatible. It was also observed that, with thermal barrier coating, specific fuel consumption (SFC), hydrocarbon (HC) and carbon monoxide (CO) values of the gasoline engine decreased; but NOx and exhaust gas temperature (EGT) increased. Furthermore, it was determined that results obtained through mathematical modeling reduced the number of test repetitions. Therefore, it was understood that time, fuel and labor could be saved in this way.

Valve fault detection for single-stage reciprocating compressors

In the present study, a zero-dimensional numerical method is developed based upon the crank angle to investigate reciprocating natural gas compressor with valve faults. This model aims to take piston movement, valve dynamic, and mass flow rate through valve and orifice equations into account. To this end, three control volumes including compressor cylinder, suction, and discharge chambers with equivalent mass and energy equations are investigated. Valve faults, which include valve plate failure, wearing on the plate and its seat, and springs deterioration, lead to valve leakage. For valve leakage simulation, a hole in the valve plate is considered. Simulated results validate the previous experimental results for normal operating compressor with healthy valves. The predicted results show that the suction and discharge valve failures decrease compressor mass flow rate and increase discharge gas temperature. Furthermore, effect of the suction valve fault is more serious than that of the discharge valve fault. In addition, valve fault can be detected by monitoring the gas temperature of the suction and discharge chambers.

Performance enhancement of the synchronous micropump based on experimental and numerical investigations of the magnetic field flux density in planar microcoils

This study presents numerical and experimental investigations targeting enhancing the magnetic field flux magnitudes in electroplated copper microcoils. Improved designs are used in the development of a new generation of the electromagnetic-based synchronous micropump in order to enhance its performance (i.e. the maximum achievable output pressure and flow rate). The synchronous micropump concept is based on managing the movement of two magnets in an annular fluidic channel. The magnets’ rotation is achieved by sequentially activating a set of three-dimensional microcoils to repel or attract one magnet (travelling piston) through the channel, whereas the second one is anchored between the inlet and the outlet ports (valve piston). At the end of each pumping cycle, the magnets exchange their functions. To achieve the maximum achievable output pressure and flow rate, higher magnetic fields without exceeding the material temperature limitation are required. The stronger the magnetic fields that can be generated, the higher the hydraulic power that the pump can deliver. The microcoil conductor width and height were optimized to generate higher magnetic field flux intensity within the pump limitation parameters (i.e. pump footprint and coils’ maximum heat dissipation limit). The new generation of the synchronous pump was run at a rotational speed of up to 800 rpm and provided a maximum flow rate of 3.56 ml/min and a maximum pressure head of 687 Pa.

A two-phase single-reciprocating-piston heat conversion engine: Non-linear dynamic modelling

A non-linear dynamic framework is presented for the modelling of a novel two-phase heat engine termed ‘Up-THERM’, which features a single solid moving-part (piston). When applied across the device, a constant temperature difference between an external (low- to medium-grade) heat source and an external heat sink is converted into sustained and persistent oscillations of pressure and volumetric fluid displacement. These oscillations are transformed in a load arrangement into a unidirectional flow from which power is extracted by a hydraulic motor. The Up-THERM engine is modelled using a system of first-order differential equations that describe the dominant thermal/fluid processes in each component of the device. For certain components where the deviations from a linear approximation are non-negligible (gas spring in the displacer cylinder, check valves and piston valve, and heat exchangers), a non-linear description is employed. A comparison between the linear and non-linear descriptions of the gas spring at the top of the displacer cylinder reveals that the non-linear description results in more realistic predictions of the oscillation frequency compared to experimental data from a similar device. Furthermore, the shape of the temperature profile over the heat-exchanger surfaces is modelled as following a hyperbolic tangent function, based on findings from an experimental investigation. Following the validation of these important device components, a parametric study is performed on the Up-THERM engine model with the aforementioned non-linear component descriptions, aimed at investigating the effects of important geometric parameters and of the heat-source temperature on key performance indicators, namely the oscillation frequency, power output and exergy efficiency of the engine. The results indicate that the geometric design of the displacer cylinder, including the height of the gas spring at the top of the cylinder, and the heat-source temperature have the most significant influence on the performance of the engine. A maximum exergy efficiency of 2.8% and a maximum power output of 175W are observed at the proposed operating temperature of 450°C for a nominal Up-THERM design (based on the physical dimensions of a device prototype and water as the working fluid; the role of the working fluid is explored in follow-up paper Ref. [1]) but with shorter displacer cylinder gas-spring lengths relative to a nominal design. The results and insight can assist the further development of this technology, in particular as a prime mover in combined heat and power applications.

Fluid flow modeling and experimental investigation on automobile damper

The liquid flow through orifices produces larger damping, whereas the cushioning effect comes from the fluid’s compressibility. The hydraulic damper design is subjected to constant high pressure necessary to achieve the required forces, which drastically increases during the dynamic operation. Damper has different orifices or piston valves that lead to different flow losses. The main objective behind this work is to investigate the effect of number of orifices on the damping force at different velocities for rear side two-wheeler automobile mono tube damper. Three different orifice opening cases are considered for simulations and experiments such as two-orifice opening, six-orifice opening and ten-orifice opening.