bluuebunny/crossref_metadata_2025 huggingface dataset:
Three-way catalyst assessment via outlet—inlet temperature measurements: Driving tests
Authors: Sparis P D , Botsaris P , Karkanis A , Tatsios J
Published: October 2002

This paper presents and discusses experimental data obtained during driving tests simulating the test cycle, ECE 15, and relates exhaust gas levels of hydrocarbon (HC) and carbon monoxide (CO) to catalyst outlet—inlet temperature differences. It also presents the preliminary results from the operation of a microcontrolled on-board diagnostics (OBD) II catalyst efficiency assessment system based on a statistical analysis of the catalyst outlet—inlet temperature difference thermocouple signal. There are indications that this system performs satisfactorily after an adequate warm-up period, if a sampling period in the order of 300—400 s is allowed.

Although this operating principle is supported by considerable experimental evidence, there are several technical problems that must be overcome before it can comply to the OBD II requirements. Firstly, as engine loads increase, the efficiency of all catalysts tested is improved considerably by the high exhaust gas temperatures. Furthermore, as the catalyst outlet—inlet temperature difference tends to decrease, so does the sensitivity of the measurements. During driving, catalyst outlet—inlet temperature differences could also be affected by other external factors such as the car speed, rain or snow etc., or long-term temperature sensor drift. Present results indicate that catalyst outlet—inlet temperature difference is also influenced by the ambient temperature. A preliminary analysis of the data indicates that a linear relationship may exist between these two quantities, however, more tests are required for a statistical proof of this assertion.

In spite of these problems, the results presented here tend to support the idea that a catalyst performance assessment system using temperature probes is technically feasible. However, further tests are required under various engine operating conditions and environments before a final conclusion can be drawn.
Engine performance monitoring using spark plug voltage analysis
Authors: Zhao H , Ladommatos N
Published: October 2002

Spark plug based engine combustion diagnostics have the advantage of simplicity and easy access. Over the years there has been considerable interest in developing and applying spark plug ionization probes to monitor the in-cylinder combustion process. In this paper, alternative approaches are presented using the spark plug as the primary sensor. These methods are based on the analysis of the spark voltage and a secondary high-voltage discharge. A series of experiments have been conducted to evaluate their potential in the measurement of combustion quality and the detection of misfire. It is found that the spark voltage decay time is related to the initial flame kernel development and may be used to detect misfire and deteriorating combustion quality in the initial flame development. The results also show that the analysis of secondary voltage decay time could be an effective means of monitoring the combustion quality and detecting misfire during the main combustion period.
Thermodynamics in a turbocharged direct injection diesel engine
Authors: Chan S H
Published: October 2002

Software has been developed for the calculation of the thermodynamic cycle and the entropy changes in a turbocharged, direct injection, diesel engine based upon the measured cylinder pressure and a shaft encoder output. Assumptions of homogeneous mixture and equilibrium thermodynamic properties are made for the products of combustion and the temporal variation in the fluid thermodynamic state is followed in a quasi-steady manner through a series of adjacent equilibrium states, each separated by finite intervals of one degree crank angle (1°CA). The thermodynamic properties are calculated by either of two equivalent formulations — equilibrium constants or minimization of Gibbs free energy, and are expressed in algebraic equations for the partial derivative of internal energy and gas constant with respect to temperature, pressure and equivalence ratio.

The effect of the engine operating conditions on the thermodynamic cycle is studied. Results show that the dynamic fuel injection timing and hence the ignition delay are strongly influenced by the operating conditions, and this explains the reasons for incorporating a fuel injection control system in modern vehicular engines for the optimization of the engine combustion cycle.
The effects of carbon dioxide in exhaust gas recirculation on diesel engine emissions
Authors: Ladommatos N , Adelhalim S M , Zhao H , Hu Z
Published: October 2002

The investigation was conducted on a high-speed direct injection diesel engine and was concerned with the effects of exhaust gas recirculation (EGR) on diesel engine combustion and emissions. In particular, the effects of carbon dioxide (CO2), a principal constituent of EGR, on combustion and emissions were analysed and quantified experimentally.

The use of CO2 to displace oxygen (O2) in the inlet air resulted in: reduction in the O2 supplied to the engine (dilution effect), increased inlet charge thermal capacity (thermal effect), and, potentially, participation of the CO2 in the combustion process (chemical effect). In a separate series of tests the temperature of the engine inlet charge was raised gradually in order to simulate the effect of mixing hot EGR with engine inlet air. Finally, tests were carried out during which the CO2 added to the engine air flow increased the charge mass flowrate to the engine, rather than displacing some of the O2 in the inlet air.

It was found that when CO2 displaced O2 in the inlet charge, both the chemical and thermal effects on exhaust emissions were small. However, the dilution effect was substantial, and resulted in very large reductions in exhaust oxides of nitrogen (NO x) at the expense of higher particulate and unburned hydrocarbon (uHC) emissions. Higher inlet charge temperature increased exhaust NO x and particulate emissions, but reduced uHC emissions. Finally, when CO2 was additional to the inlet air charge (rather than displacing O2), large reductions in NOx were recorded with little increase in particulate emissions.
Simulation models for hybrid buses
Authors: Berta G L , Durelli E , Nymann I
Published: October 2002

Design and production of hybrid buses in Italy are assisted by a range of engineering tools that enable simulation and optimization of the hybrid bus performance. A review of these tools is given, involving the study and development of typical driving patterns and behaviour, the mathematical models of the components in the hybrid powertrain and, finally, the application of the computer codes.

Initially simulation is a design tool. Moreover, it is found that simulation is useful for verifying the suitability of hybrid buses for the required service. By means of more or less complex algorithms, customers can be advised to adapt bus lines and to adjust powertrain parameters.
The formula commonly used to calculate velocity change in vehicle collisions
Authors: Smith R
Published: October 2002

A vehicle's velocity change in a crash, Δ v, is helpful in the scientific investigation of road traffic accidents. This note discusses the formula commonly used to calculate Δ v. A new derivation of this formula for planar motion is given here. The derivation is based upon the conservation laws and leads to an extension of the existing formula. It is not necessary to assume any deformation law for the vehicles in order to obtain the results. The new derivation clarifies the conditions under which the commonly used formula is valid. It shows that the masses and yaw moments of inertia of the vehicles must not be significantly changed by the collision. Further, tyre and other forces must be negligible when compared with the impulsive forces generated by the impact. Finally, there is a condition on the components of the velocities at the point where the resultant impulses act. The analysis shows that the commonly used formula neglects restitution effects and so tends to underestimate the actual velocity change. In fact, restitution effects are important for low-speed impacts. Impact speed calculated from the commonly used formula is not as accurate as speeds obtained by other methods. Nevertheless, in the absence of any marks on the road, such calculations may be the only way of scientifically estimating a vehicle's speed.
Theoretical and experimental study of a fluidic device as a fuel injector for natural gas engines
Authors: Chen R , Huang Q , Lucas G. G.
Published: October 2002

A novel fluidic gaseous fuel injector, designed for natural gas engines, has been tested and analysed in this paper. The injector is based on the use of a mono-stable fluidic amplifier. Its steady state and dynamic characteristics were tested and compared with several commercial solenoid gas injectors on a laboratory test rig. The results show that the fluidic gas injector is able to handle the large gas flowrates required by natural gas engines with a faster switching response and higher injection stability. Also, the steady state attachment and dynamic switching response of the jet flow in the fluidic amplifier were analysed by a mathematical simulation model. The agreement between predicted and experimental results is shown to be good.
Prediction of the effect of injection parameters on NOx emission and burning quality in the direct injection diesel engine using a modified multizone model
Authors: Salem H , El-Bahnasy S. H. , Elbaz M
Published: October 2002

Combustion process in a quiescent chamber diesel engine is modelled using a multizone model. This model divides the cylinder charge into two zones, namely the unburnt zone (surrounding air) and the burnt zone (fuel spray with entrained air). The burnt zone is subdivided into 16 concentric sprays, instead of only eight sprays as in previous work, each one with its own temperature and composition. Liquid fuel, fuel vapour, air and products of combustion are assumed to be present in each zone. Real gas relations are used to calculate the properties of the mixture while products of combustion are assumed to be in chemical equilibrium at local temperature. The extended Zeldovich mechanism is used to predict the NO x formation. The cylinder pressure, temperature, heat release rate, NO x rate and concentration are calculated. For different injection pressures, injection advance angles and different fuel orifice hole diameters, the results show that the model can predict the measured cylinder pressure with high accuracy but it predicts the measured heat release rate and NO x emission rate with moderate accuracy. In addition, the effect of injection parameters on the NO x emission and engine power is predicted and it has been shown that NO x emission can be reduced without noticeable loss of engine power. This can be done by appropriate choice of injection pressure, injection advance angle and fuel nozzle hole diameters.
A new total variation diminishing scheme for the calculation of one-dimensional flow in inlet and exhaust pipes of internal combustion engines
Authors: Vandevoorde M , Vierendeels J , Dick E , Sierens R
Published: October 2002

Total variation diminishing (TVD) schemes have been recently introduced for the calculation of the one-dimensional unsteady flow in the inlet and outlet pipes of internal combustion engines. This paper describes the flux difference splitting technique (with first- or second-order upwind fluxes) for the classic TVD schemes. To avoid problems at nodes with a section change, a new TVD scheme is developed. This paper further describes a method to impose the boundary condition at the pipe end, independent of the numerical scheme used. This is shown for a reservoir inlet of the pipe and a subsonic outlet flow.

For two test cases (the shock-tube and the tapered-pipe calculation), the new TVD algorithm is compared with the classic TVD schemes. The evaluation shows that the new cell—vertex TVD scheme with superbee limiter in two stage form combines a high accuracy with an exact representation of the mass flow in each of the nodes.
Vehicle dynamics and control synthesis for four-wheel steering passenger cars
Authors: You S-S , Jeong S-K
Published: October 2002

This paper is concerned with the active robust autopilot design of a four-wheel steering vehicle against external disturbances. Firstly, the effect of four-wheel steering and independent wheel torques for lateral/directional and roll motions is modelled by a set of linear models under proper manoeuvring conditions. To enhance the dynamic performance of an automobile system, a mixed H2/H∞ synthesis with pole constraint is designed on the basis of full state feedback applying linear matrix inequality (LMI) theory. For lateral/directional and roll motions, the steering angles are actively controlled by steering wheel angles through the actuator dynamics. The wheel power and braking are also controlled by independent wheel torques. Simulation results indicate that the proposed control approach can achieve predetermined performance (or acceptable level of disturbance attenuation) and stability as well as robustness even when external disturbances are severe. The active 4WS car along with steering and wheel torque control algorithms allows greater manoeuvrability and improved stability in a wide range of uncertainty.
Investigation into hydrocarbon emissions from crevice and oil film during cold start and idling periods in a spark ignition engine
Authors: Huang Z , Pang J , Pan K , Jiang D , Zhou L , Yang Z
Published: October 2002

In order to understand better the process of hydrocarbon formation and the effect of the top-land crevice and the oil layer of the cylinder liner on unburned hydrocarbons during cold start and idling periods, the temperature of the piston top-land and liner was measured. Based on the measured results, the amount of unburned hydrocarbons from the crevice and liner has been predicted. It was found that the temperature of the piston top-land and cylinder liner took about 150-200 s to reach its equilibrium state as the engine started up. The concentration of hydrocarbons from the top-land crevice and from the oil layer will be reduced to 40 and 75 per cent of its initial value respectively. It is considered that a reduction in piston thermal capacity can reduce the total unburned hydrocarbons during this transient period owing to quick minimization of the top-land crevice volume and rapid increase in mixture temperature in the crevice region.
Impact of alternative controller strategies on exhaust emissions from an integrated diesel/continuously variable transmission powertrain
Authors: Deacon M , Brace C. J. , Vaughan N. D. , Burrows C. R. , Horrocks R. W.
Published: October 2002

The use of an integrated powertrain including a continuously variable transmission (CVT) offers great scope for improvements in fuel consumption and emissions, although this must be achieved without adversely affecting vehicle drivability. These conflicting aims can best be resolved by the use of novel control strategies designed from the outset with these considerations in mind. Two alternative approaches to the task are presented here. These made use of artificial intelligence and more traditional and intuitive methods to allow the maximum flexibility in operation. Both strategies incorporated a novel optimization routine described in a companion paper to locate the best operating point for the engine. The two strategies were implemented for an integrated diesel CVT powertrain and compared with an existing controller and the equivalent manual transmission powertrain. Chassis dynamometer results show the newly designed controller strategies to have significant impact on vehicle exhaust emissions, while the structure of the software allows the controller action to be highly tuneable and fexible in order to balance the vehicle drivability requirements with economy and emissions targets.
Non-parametric models in the monitoring of engine performance and condition: Part 2: Non-intrusive estimation of diesel engine cylinder pressure and its use in fault detection
Authors: Gu F , Jacob P. J. , Ball A. D.
Published: October 2002

An application of the radial basis function model, described in Part 1, is demonstrated on a four-cylinder DI diesel engine with data from a wide range of speed and load settings. The prediction capabilities of the trained model are validated against measured data and an example is given of the application of this model to the detection of a slight fault in one of the cylinders.
Variable geometry turbocharging for lower emissions and improved torque characteristics
Authors: Hawley J. G. , Wallace F. J. , Cox A , Horrocks R. W. , Bird G. L.
Published: October 2002

Currently, 80 per cent of European diesel passenger cars are turbocharged and, as emission standards become more stringent, this figure is expected to approach 100 per cent in the near future. One major focus that has emerged for the high-speed diesel engine is the application of variable geometry turbocharging (VGT). An extensive steady state experimental investigation has been undertaken on a prototype 1.8 L direct injection (DI) diesel engine to compare the potential benefits of VGT relative to the standard build of the engine with a wastegated fixed geometry turbocharger (FGT). Under part load operation, where emission production is significant in the European drive cycle, independent control of both VGT vane position and exhaust gas recirculation (EGR) valve position was used to optimize emission levels. A reduction in the levels of nitrogen oxides (NO x) of up to 45 per cent was observed at discrete operating points without compromising FGT levels of fuel consumption or smoke. Under limiting torque conditions a 10 per cent improvement was achieved with the VGT over and above the figures of the baseline FGT build within the limiting criteria set for maximum cylinder pressure, smoke level and pre-turbine temperature.
In-cylinder fuel behaviour and exhaust emissions during the cold operation of a spark ignition engine
Authors: Shayler P. J. , Belton C
Published: October 2002

A model has been developed from experimental results to describe the passage and utilization of fuel after injection to its exhaust as fuel products or loss to the crankcase during warm-up after a cold start. Engine-out emissions of unburned hydrocarbons (HCs) and carbon monoxide can be predicted for both quasi-steady and transient engine operating conditions during warm-up. The model is phenomenological. Model coefficients, which are either constants or simple functions of engine coolant temperature, have been determined for best matching of predictions to experimental data covering a wide range of conditions. The model has been used to investigate the variation in in-cylinder fuel film mass, fuel lost to the crankcase, exhaust air—fuel ratio variations and engine-out emissions. The dependence of these on steady and transient engine operating conditions is described.
Cycle-by-cycle modelling of NO formation and comparison with experimental data
Authors: Ball J. K. , Stone C. R. , Collings N
Published: October 2002

Experimental data were obtained from a Rover K4 optical access engine and analysed with a combustion analysis package. Cyclic NO values were calculated by mass averaging the measurements obtained by a fast NO analyser. The modelled NO results were compared with the experimental values on plots of NO versus peak cylinder pressure, Pmax. The model achieves its cyclic variability through the input of experimentally derived burn rates and a completeness of combustion parameter. This is based on the Rassweiler and Withrow method for calculating the mass fraction burned and is derived from the pressure—crank angle record of the engine. The cycle-by-cycle NO modelling results are found to compare well with the experiments in terms of the mean value for all cycles, the general slope of the NO versus Pmax line and the maximum and minimum values (or spread). The modelled results do not, however, exhibit the same degree of scatter as the experimental data. This is attributed to the model utilizing a fixed blow-by rate, a constant temperature at inlet valve closure and a constant residual mass fraction for all cycles at a given operating point.
Reduction in polycyclic aromatic hydrocarbon emission and air pollution by using a methanol-containing additive in a gasoline-powered engine
Authors: Wu T-D , Chen Y-N , Tse C-C , Wang C-N , Wu S-J
Published: October 2002

A gasoline powered engine installed and operated on an engine dynamometer was used to investigate the reduction in polycyclic aromatic hydrocarbon (PAH) emission and air pollution [CO, hydrocarbons (HCs), NOx] by using a methanol-containing additive (US Department of Commerce Patent and Trademark Office Certification No. 5688295, 18 November 1997). Mixtures of 25 per cent methanol with 75 per cent 95 lead-free gasoline (LFG), 25 per cent methanol with 75 per cent 92 LFG and 25 per cent methanol with 75 per cent premium leaded gasoline (PLG) were used as the power fuels. The engine was simulated for the idling condition and for cruising engine speeds of 1500, 2000 and 3000 r/min. The concentrations of 21 individual PAHs and air pollutants in the engine exhaust emissions were determined. The experimental results proved that the methanol-containing additive obviously promotes PAH and air pollution reduction, especially at an engine speed of 1500 r/min. The concentration of carcinogenic compounds—benzopyrene (BaP), dibenzanthracene (DBA), indenopyrene (IND) and benzoperylene (BghiP)—found in major vehicle fuels is approximately zero in the methanol-containing additive.
Development of a heavy-duty chassis dynamometer driving route
Authors: Nine R. D. , Clark N. N. , Daley J. J. , Atkinson C. M.
Published: October 2002

There is presently a lack of realistic driving cycles or schedules for the chassis dynamometer emissions testing of heavy-duty trucks. This research effort was motivated by the need for representative emissions measurement techniques to compare alternatively fuelled trucks with their diesel or gasoline counterparts operating in heavy-duty truck applications. Speed versus time and video recording data gathered from trucks in local delivery use were used to develop a city/suburban heavy vehicle route (referred to as the CSHVR) for Class 7 (11 794-14969 kg gross vehicle weight) and Class 8 (14969-36287 kg) delivery trucks. Statistical data were gathered on actual truck driving behaviour, as well as 60 h of actual speed versus time driving information. A cycle was then developed by joining microtrips from the actual truck operation and verifying that it was representative of the whole database. A driving route was derived from this cycle with the help of the video data, and with the vehicle deceleration rates modified for practical reasons. It was found that a more powerful truck could bias its exhaust gas emissions by not aggressively applying full power while following a conventional speed versus time trace cycle. In comparison with a speed versus time cycle, a route allows sections of free acceleration (at full power) until a desired overall operating distance is met. A route is defined by a path that a truck must follow where driving instructions are dependent upon the acceleration of the truck, road conditions and speed limitations. The new route has been successfully employed in the emissions testing of several Class 8 tractors and was found to yield emission rates (in g/mile) that were higher than those for the previously documented WVU five-mile route (8 km in length) in the case of a Ford 36287 kg (80000 lb) GVWR tractor with a mechanically injected Cummins 261 kW (350 hp) engine.
Reducing cold-start emission from internal combustion engines by means of a catalytic converter embedded in a phase-change material
Authors: Korin E , Reshef R , Tshernichovesky D , Sher E
Published: October 2002

Under normal operating conditions, catalytic converters appear to be the most effective means of reducing air pollution from internal combustion (IC) engines. The conversion efficiency, however, declines very steeply for temperatures below about 350°C and is practically zero during the starting and warming-up period. Improving the conversion efficiency under these conditions is important, particularly in large cities, where the number of startings per vehicle per day tends to be high. Among the more successful solutions are preheating of the catalyst electrically, warming up of the catalyst in an external combustion chamber, installation of an auxiliary small-capacity catalytic converter, and employment of an adsorbing unit between two catalysts. Although these methods are quite effective, their disadvantage lies in the fact that they require an external energy source, an additional component (a control unit) or a three-stage catalyst. In the present work an investigation was made of a solution based on the exploitation of thermal capacitance to keep the catalyst temperature high during off-operation periods. A phase-change material (PCM) with a transition temperature of 352.7°C, which is slightly above the light-off temperature of the metallic catalyst, was specially formulated, and a system comprising a catalytic converter embedded in the PCM was designed and tested. Under normal engine operating conditions, some of the thermal energy of the exhaust gases was stored in the PCM. During the time that the vehicle was not in use, the PCM underwent partial solidification, and the latent heat thus produced was exploited to maintain the catalyst temperature within the desired temperature range for maximum conversion efficiency.
Evaporation of hydrocarbon compounds, including gasoline and diesel fuel, on heated metal surfaces
Authors: Fardad D , Ladommatos N
Published: October 2002

An investigation was carried out on the evaporation of various hydrocarbon liquids on heated surfaces. Single and multicomponent hydrocarbon compounds were used, including hexane, heptane, octane, a hexane—octane mixture, gasoline and diesel fuel. The heated surfaces included aluminium, mild steel, cast iron and copper. Tests were also carried out with different surface textures and surface coatings. The motivation for this work was a desire to improve understanding of the evaporation processes taking place in the inlet port and, to a lesser extent, within the combustion chamber of internal combustion engines.

The hydrocarbon compounds were released on to the heated surfaces as individual small droplets, and the subsequent evaporation was recorded using a CCD (charge coupled device) camera. These observations were then used to ascertain the effects of material, surface temperature, surface texture, surface coating and liquid composition on the heat flux and other aspects of droplet behaviour.
Plant machinery working life prediction method utilizing reliability and condition-monitoring data
Authors: Goode K B , Moore J , Roylance B J
Published: October 2002

A recently developed condition-based maintenance model is described which utilizes reliability data combined with condition-monitoring and measurements to predict the remaining useful life of critical components in a hot strip steel mill. The results obtained from case studies are presented which indicate how the model can be used as part of a condition-based maintenance strategy.
A pneumatic gauging sensor for measuring the thickness of soft films
Authors: Bridge S P , Robbins P T , Paterson W R , Wilson D I
Published: October 2002

The use of the pneumatic gauging technique for measuring the thickness of soft films of food materials on hard surfaces was investigated using devices with 45° converging nozzles and 1 mm throat i.d., at air pressures of 250–1960 Pa g and different nozzle rim widths. The quasi-linear pressure response in the gauging region (clearance of less than 300 μm) and the discharge coefficient for the nozzle at low clearances were found to be independent of the upstream pressure, nozzle Reynolds number and nozzle rim width. Draughts made measurements at low pressures difficult; therefore the results reported here are principally for gauging pressures greater than 700 Pa g. The force exerted on the surface proved to be strongly affected by the nozzle shape. The flow from narrow-rimmed nozzles behaved as impinging laminar jets, whereas wide-rimmed devices exhibited lift forces caused by inertial effects in radial flows. The former would seem to be more suitable for gauging soft films and tests on a range of foodstuffs indicated that reasonable accuracy (±20 μm) could be readily achieved on materials which present a quasi-rigid surface with low permeability. Experiments established desirable gauge design and operating procedures, namely (a) narrow-rimmed nozzles, (b) low air supply pressures and (c) performing measurements at the maximum linear clearance, at h/d t ≍ 0.25. The gauging technique failed with viscous materials lacking a finite yield stress and on soft sponges.
Stability of open-channel trickling-filter distributor arms
Authors: Duncan C , Jones I A
Published: October 2002

A method is presented for predicting the stability of the rotating arms of a rotary sewage distributor incorporated into a trickling filter. The method is derived, tested via various laboratory demonstrations and employed for evaluating the stability of experimental and production distributors using a calculation based upon the distributor's experimentally determined stiffness matrix. The method correctly models the stability behaviour of the laboratory rigs and confirms the observation that the experimental distributor is on the borderline of stability, while the production distributor is stable by a comfortable margin. A procedure is then developed for predicting the stability of a distributor prior to construction, using a finite element model to calculate the distributor's stiffness matrix.
Pipeline system identification through cross-correlation analysis
Authors: Beck S B M , Williamson N J , Sims N D , Stanway R
Published: October 2002

The pipeline systems used to carry liquids and gases for the ventilation of buildings, water distributions networks, and the oil and chemical industries are usually monitored by a multiplicity of pressure, flow, and valve position sensors. By comparing the input signal to a valve with the pressure reading from the network using cross-correlation analysis, the technique described in this paper enables a single sensor to be used for monitoring. Specifically, the offset and gradient change of the cross-correlation function show the time delay between the input wave and the acquired output signal. These reflections arise from junctions, valves, and terminations, which can be located effectively using the cross-correlation technique.

Investigations using a T-shaped pipe network have been conducted with a valve inserted in the pipeline to introduce artificial water hammer-type perturbations into the system. Both computational and experimental data are presented and the results are compared with the actual pipe network geometry. It is shown that it is possible to identify the location of various features of the network from the reflections and thus to perform either system characterisation or condition monitoring.
A theoretical analysis on the failure of unpressurized and pressurized pipelines
Authors: Shen W Q , Shu D W
Published: October 2002

A theoretical quasi-static analysis is proposed to predict the response and the onset of failure for pipelines. The maximum strain criterion, the effect of strain rate and an empirical formula for estimating the length of a plastic hinge are employed in the analysis. This theoretical study allows the local or denting deformation to continue during the global deformation phase. A good agreement has been achieved between the theoretical predictions and the corresponding experimental results for the threshold value of the impact energy and the maximum permanent transverse deflection for both unpressurized and pressurized pipelines. It transpires that both the maximum strain criterion and the empirical formula for the hinge length are applicable in the theoretical analysis. With a simple computer program, the theory can be used to predict the failure of pipelines. Discussions are made for the influence of internal pressure on the shape of the indentation and the threshold value of the impact energy.
Particle degradation in pneumatic conveyors: Use of data from a pilot-sized test facility to predict degradation in an industrial conveyor
Authors: Bridle I , Woodhead S R
Published: October 2002

Degradation of bulk solid product during pneumatic conveying is of concern in a range of process industries. However, prediction of product degradation levels at the conveyor design stage has proved challenging. This paper presents a proposed prediction technique, based on the use of a pilot-sized test facility to provide relevant empirical data. The results of experiments undertaken using malted barley, basmati rice, and granulated sugar are reported. For each bulk solid material, a wide range of conveying conditions have been examined, consistent with common industrial practice. Correlations between predictions and experimental data obtained in an industrial-scale conveyor are presented and discussed.
Velocity measurements in a ceramic candle filter element undergoing pulse cleaning
Authors: Biffin M , Panagiotidis P , Pitsillides C
Published: October 2002

Ceramic candle filters have been developed for cleaning high-temperature gas streams. They have demonstrated high collection efficiencies under normal operating conditions, but the brittle materials can fail suddenly with disastrous consequences. Reverse pulse cleaning has been shown to introduce severe thermal stressing of the material. Modelling of the flows to estimate the life of the element is difficult due to non-uniformities in the material. It is important to obtain experimental measurements of flows in the candle to provide input to stress models. In addition it is essential to ensure uniform cleaning of the filter and knowledge of the pulse cleaning flow processes are also important for this.

This paper reports velocity measurements obtained using a hot-wire probe located at different positions along the length of a ceramic candle filter. The data have been analysed to estimate the outflow along the length of the candle filter to investigate the cleaning potential of different configurations and operating parameters.

The effect of pulse length on cleaning performance was investigated for cases with and without a venturi educer. It was found that the maximum peak mean velocity was produced at a pulse duration of 0.2 s. Longer duration pulses did not have a significant influence on the maximum velocity levels inside the filter.
An overview of metals recycling by physical separation methods
Authors: Veasey T J
Published: October 2002

In the secondary metals industries mechanical/physical separation processes predominate for the recovery of metals from post-consumer wastes of all types. Nearly all of the concentration methods used in the metals recycling industries have been developed from well-established mineral beneficiation technologies, but recently there have been innovative developments in new or improved separation processes specifically designed to treat waste materials. Conventional physical separation systems are reviewed and briefly described and recent developments are also discussed.
Fault diagnosis of pumping machinery using artificial neural networks
Authors: Ilott P W , Griffiths A J
Published: October 2002

Pumping costs within British industry are enormous, with the potential for considerable financial savings through fault diagnosis and condition-based maintenance. Accurate condition monitoring data interpretation is a key requirement in pump fault diagnosis. However, the human skills required to transform monitored data into maintenance information are often unavailable. Artificial neural networks (ANNs) are proposed for automation of this skill in the development of a pumping system decision support tool, the key requirement of which is accurate pump fault diagnosis.

The cumulative sum charting procedure was used to establish a knowledge base of fault data for ANN implementation based on historical parameter measurements. Various preprocessing techniques were investigated in relation to generalization ability and convergence rates during the learning phase. Preprocessing predominantly aVected ANN convergence rate, with the quality of training data crucial to generalization ability. ANNs could provide accurate, incipient fault diagnosis of pumping machinery based on real industrial data corresponding to historical pump faults.
Computational and experimental investigations in a cyclone dust separator
Authors: Fraser S M , Abdel-Razek A M , Abdullah M Z
Published: October 2002

Three-dimensional turbulent flow in a model cyclone has been simulated using PHOENICS code and experimental studies carried out using a laser Doppler anemometry (LDA) system. The experimental results were used to validate the computed velocity distributions based on the standard and a modified k-∊ model. The standard k-∊ model was found to be unsatisfactory for the prediction of the flow field inside the cyclone chamber. By considering the strong swirling flow and the streamlined curvature, a k-∊ model, modified to take account of the Richardson number, provided better velocity distributions and better agreement with the experimental results.
Detection of incipient cavitation in pumps using acoustic emission
Authors: Neill G D , Reuben R L , Sandford P M , Brown E R , Steel J A
Published: October 2002

This work concerns the detection of incipient cavitation in pumps using acoustic emission (AE). Three activities have been pursued in this context: (a) the construction of a small-scale rig for the investigation of cavitation detection using AE sensors; (b) the acquisition of data on a 75 kW single-stage centrifugal pump in an industrial test loop under normal running and cavitation conditions; (c) the determination of parameters that could be used for the early diagnosis of cavitation within pumps.

In the laboratory-scale apparatus water was pumped around a short loop by a 3 kW centrifugal pump. The flow loop contained a section specifically designed to induce cavitation by means of reducing the pressure level to that of the vapour pressure of the fluid. This apparatus was used to produce a variety of well-controlled cavitation conditions which were useful in determining the suitability of AE for the detection of cavitation.

The industrial-scale tests consisted of progressively reducing the net positive suction head in a 75 kW pump while recording the AE signals at various points on the test loop and pump.

Results are presented from both laboratory and full-scale tests which demonstrate the feasibility of detecting incipient cavitation using AE in the face of background noise from normal running of the pump. The features of AE which are indicative of cavitation are also seen to change continuously as NPSH is decreased. Thus early detection of cavitation is possible, certainly before any indication is seen on the dynamic head.
Process plant condition monitoring and fault diagnosis
Authors: Sharif M A , Grosvenor R I
Published: October 2002

The paper reviews current research work in the field of process condition monitoring and fault diagnosis. The review compares and contrasts the applicability and efficiency of different techniques, and concentrates on methods which monitor the main process variables. From the wide range of methods and process variables, temperature, flowrate and liquid level are used here in comparing the limitations and applications of each method. The scope of the paper ranges from basic, well established techniques to the latest reported monitoring strategies for each of the process variables.

Furthermore, the different methods of fault diagnosis deemed to be relevant in process plant are reviewed. The detection of the internal leakage in the control valves and motor faults are discussed in detail, as examples of the monitoring of vital process plant components.

The paper then outlines areas of future work, such as the development of a user friendly interface. This interface is based on state transition diagrams (STDs) as well as on the use of a knowledge based system (KBS) to model and diagnose faults in vital process plant components such as control valves.
A methodology for risk-based inspection of pressurized systems
Authors: Hagemeijer P M , Kerkveld G
Published: October 2002

This paper describes a methodology for risk-based inspection and focuses on the planning of inspection activities. Brunei Shell Petroleum (BSP) operates a large number of ageing production and evacuation facilities in the South China Sea, and is facing the challenge to identify the optimal inspection effort in a period of time when more production is required and operating costs have to be minimized. Since 1989 major investments (annual costs about 15 million US$) were made to perform base line inspections which resulted in corrective work and a large repository of equipment integrity data. These data require analysis and updating, as defined in this methodology. The challenge is for BSP to implement risk-based inspection of static equipment, which so far has been very successful.

The methodology is based on the determination of risk by evaluating the consequences and the likelihood of equipment failure. Likelihood of failure is assessed, by means of extrapolation, at the future planned maintenance campaign to identify the necessary corrective work. The extrapolation is based on historical inspection and maintenance data as well as on anticipated future operating conditions. Such an analysis requires in-depth knowledge of the equipment regarding functions, operating conditions, materials, imposed potential failure modes and causes, and their controlling parameters (integrity parameters). The novelty of the method is that equipment integrity is expressed in terms of integrity parameters, which can be measured and trended. Consequently, based on defined limits for the integrity parameters (i.e. anomaly classifications), actions for managing risk to an acceptable low level can be identified. The transparent linkage between monitoring activities (e.g. inspection) and integrity parameters offers an effective framework to manage and to demonstrate integrity against clear quantifiable acceptance limits. By pursuing the above methodology for all equipment, a list of inspection activities, prioritized on equipment condition and the risk of failure, can be derived.

Within BSP this has resulted in a demonstrated increased efficiency of the inspection effort, a focused strategy for repairs executed on a campaign basis, and an improved quantification of BSP's facilities integrity. The approach has been proven in the company to be practical and it can be implemented relatively quickly.
Design of small-rate feeders for non-free-flowing materials: A case study
Authors: Bradley M S A , Pittman A N , Dawson M J
Published: October 2002

This paper uses a case study to illustrate the problems which can occur when using small feeders to dose at low rates, with materials which are not totally free flowing. The general principles of good design for small feeders are enlarged upon, together with issues to look for when trouble shooting these equipment items.

The system in question used a screw to dose a moist pelleted talc into a process at a nominal rate which was variable at around 1 t/h and originally suffered from poor flow in the hopper, a variable dosing rate and binding of the screw, thus needing constant attention from the operator to keep it working. Various types of mechanical flow assistance device had been tried, most of which made the problem worse. The Wolfson Centre redesigned the screw and hopper of the unit, and the performance problems were cleared. The problems with the original and intermediate designs serve to illustrate very well the points that need to be observed, in obtaining good performance from small feeders.
Sensor-based performance monitoring of a control valve unit
Authors: Sharif M A , Grosvenor R I
Published: October 2002

This is the second of a series of papers dedicated to the research and development work in the field of industrial control valve condition monitoring and fault diagnosis. This paper reports new results that were produced after conducting a series of tests to monitor the dynamic performance of a typical industrial control valve unit (which consisted of a control valve, an actuator and a digital valve controller) under various operating conditions. These included the gradual blockage of the actuator's vent hole, the build-up of deposits on the valve stem and the incorrectly replaced valve stem seals.

These conditions were created by using a precision in-line flow regulator for the actuator's vent hole and a thin layer of a special type of adhesive film that crystallized and bonded to the valve stem and by replacing the polytetrafluorethylene valve stem seals with graphite-type seals under controlled conditions. The effects of these abnormalities on the pressure that was developed in the upper diaphragm casing of the actuator as well as the flowrate were carefully monitored using a range of sensors that were integrated into an intelligent data acquisition and processing system.

It was evident that certain types of fault, including the fully blocked actuator's vent hole, could be identified with great accuracy using the responses of the flow transmitter and the pressure transducer. On the other hand, other types of fault, such as the simulated build-up of deposits on the valve stem, required a comparison of their statistical properties in addition to the transducers' responses to determine the condition reliably.

The current-to-pressure converter is a vital element of any digital valve controller and its performance was, therefore, monitored under various conditions to establish the effects of the faults on its operation. The paper concludes by outlining the main results and the limitations of the diagnostic techniques utilized as well as the future work, which is to integrate the results into a user-friendly diagnostic system based on the Microsoft visual basic programming language.
Use of extended exergy analysis to evaluate the environmental performance of machining processes
Authors: Creyts J C , Carey V P
Published: October 2002

Traditional applications of exergy analysis have focused upon the optimization of energy use in thermal and chemical processes. This paper introduces a form of exergy analysis in which the methodology is extended to consider the characteristics of material flows in a process as well. This new form of analysis, termed extended exergy analysis (EEA), is shown to be particularly useful in valuating the environmental performance of industrial processes.

EEA differs from traditional theory in its requirement that all ground states be defined such that they are en6ironmentally acceptable. Environmental acceptability can be determined using a number of health, occupational and ecological criteria. By integrating biological considerations into the existing physical definition, EEA provides manufacturers and regulators alike with relevant information regarding the costs of achieving environmentally benign production. These costs are valued consistently for both raw material and energy inputs and product and residual outputs, affording degrees of transparency and objectivity not present in other valuation methodologies.

Application of the technique to a case study involving the machining of aluminium is developed.
Process control with minimum control effort
Authors: Whalley R , Ebrahimi M
Published: October 2002

The control of linear time-invariant process models is considered. Systems where there are single or multiple inputs and outputs are analysed using conventional frequency domain techniques. The use of influence functions which are employed to affect the closed-loop characteristic equation of the system model is advocated. Minimization of the control effort required, while generating a prescribed influence function is achieved, using input-output measurements only. Illustrative studies are included for demonstration purposes.