Compressed Air Supply Research Articles

Modelling and Transmission Characteristics Analysis of APU Pneumatic Servo System

The auxiliary power unit (APU), which is a compact gas turbine engine, is employed to provide a stable compressed air supply to the aircraft. This compressed air is introduced into the various aircraft components via the pneumatic servo system, thereby ensuring the normal operation of the aircraft’s systems. The objective of this study is to examine the impact of parameter variation on the transmission characteristics of an APU pneumatic servo system, with a particular focus on the aerodynamic moment associated with the operating process of a butterfly valve. To this end, a mathematical model of the pneumatic servo system has been developed. The accuracy of the mathematical model was verified by means of numerical simulation and comparative analysis of experiments. The simulation model was established in the Matlab/Simulink environment. Furthermore, the effects of throttling area ratio, fixed throttling hole diameter, rodless chamber volume of actuator cylinder and gas supply temperature on the transmission characteristics of the system were discussed in greater detail. The findings of the research indicate that the throttle area ratio is insufficiently sized, which results in a deterioration of the system’s linearity. Conversely, an excessively large throttle area ratio leads to a reduction in the controllable range of the load axis and is therefore detrimental to the servo mechanism of the flow control. An increase in the diameter of the fixed throttling hole or a decrease in the volume of the rodless cavity of the actuator cylinder facilitates a rapid change in flow rate within the rodless cavity and an increase in the response speed of the load-rotating shaft of the servomechanism. An increase in the temperature of the gas supply from 30 °C to 230 °C results in a reduction in the response time of the system by a mere 0.2 s, which has a negligible impact on the transmission characteristics of the system.

Multistable Composite Laminate Grids as a Design Tool for Soft Reconfigurable Multirotors

Adaptive‐morphology multirotors exhibit superior versatility and task‐specific performance compared to traditional multirotors owing to their functional morphological adaptability. However, a notable challenge lies in the contrasting requirements of locking each morphology for flight controllability and efficiency while permitting low‐energy reconfiguration. A novel design approach is proposed for reconfigurable multirotors utilizing soft multistable composite laminate airframes. These airframes show kinematically determinate morphologies corresponding to multiple minima in their elastic potential energy landscape. By varying design parameters, the methodology allows for tuning the energy landscape characteristics governing each morphology's structural stability and reconfiguration energetics. The airframe, composed of multistable composite laminate grids, is optimized to maximize rigidity under flight loads and minimize reconfiguration work. The 130‐g reconfigurable multirotor design demonstrates self‐locking properties in an open and a folded configuration, enabling a 48% reduction in width‐span without compromising stability during flight. Soft pneumatic actuators, actuated using a tethered compressed air supply, enable reversible reconfiguration on the ground between open and folded configurations. The design resolves the conflicting requirements of high‐stiffness to lock each flight configuration and low‐actuation work for reconfigurability. By exploiting soft yet multistable structures, the approach combines the stability observed in rigid‐linked reconfigurable multirotors with the low‐effort reconfigurability of soft multirotors, offering new methods for designing adaptive‐morphology multirotors.

Improving the transfer of dissolved oxygen in a biological Fe2+ oxidation process using a venturi jet as an intensive aeration system

The low bio-production of Fe3+ as a leaching agent is one of the main limitations to implementing industrial bio-processes at feasibility conditions. The main limitation of the bio-oxidation process of Fe2+ is the low oxygen transfer to the aqueous phase because of the low oxygen solubility. This study assesses the effectiveness of the venturi jet as an innovative and intensive aeration device for overcoming the oxygen limitation in a continuous ferrous oxidation process in a fixed-bed reactor with immobilized acidithiobacillus ferrooxidans, in contrast to the conventional diffuser aeration device. Firstly, the influence of the airflow and the influence of the medium concentration were determined for the following parameters for both aeration devices; Volumetric mass transfer coefficient (kLa), Standard Oxygen Transfer Rate (SOTR), Standard Aeration Efficiency (SAE), and Standard Oxygen Transfer Efficiency (SOTE). Then, both aeration devices were compared in a continuous bio-oxidation process in an up-flow packed bio-reactor (UFPB). The system performance was assessed by monitoring temperature, pH, oxidation-reduction potential, and dissolved oxygen concentration for 69 days. Findings displayed that when aerating with the diffuser, the ferrous oxidation rate was restricted by the low dissolved oxygen availability, being about 1 ppm (1 mg L−1). Under these oxygen-limiting conditions, the maximum ferrous (Fe2+) oxidation rate was 9.09 g L−1 h−1. However, when aerating with the venturi jet, the dissolved oxygen concentration increased up to 2.70 mg L−1, achieving a maximum of 29.11 g L−1 h−1. So, this study has demonstrated that the change in the aeration device has resulted in an improvement in the process, achieving a 3.5-fold increase in the oxidation rate. Furthermore, the venturi jet offered additional advantages over the diffuser, such as requiring less power to deliver the same amount of air, being unaffected by jarosite precipitates, and not requiring a supply of compressed air.

Причины повреждений корпусных конструкций в носовой оконечности судов

The operation of marine vessels, especially large-tonnage ones, is accompanied by the occurrence of serious damage to hull structures within bow in stormy conditions. A new mechanism to explain the catastrophic destruction of the side grillages of large-tonnage ships in the area of the bow is proposed. Simulation of the process of flow around the fore end when it is digged in a wave using SPH technology showed that when the flow speeds around the fore end occur when the vessel moves in developed waves, there is a sharp drop in pressure in certain areas of the bow end. This circumstance can lead to the occurrence of cavitation that is confirmed by modeling the process of flow around the fore end using ANSYS FLUENT software. During stall cavitation, a cavitation cavern of considerable size may arise, the collapse of which is accompanied by the occurrence of hydrodynamic loads that can destroy hull structures. A calculation method is proposed that allows one to estimate the magnitude of hydrodynamic loads acting on the ship’s hull during the collapse of a cavitation cavern. To prevent damage to the bow in storm conditions, a number of constructive measures have been proposed. One of the options for solving the problem is to install a deck fairing in the bow that eliminates the negative influence of structural cavitators in the traditional design when the bow is digged in the wave. It is also possible to install a compressed air supply system to those areas of the bow where vacuum occurs when a liquid flows around when digged in a wave.

Development of a suction gripper network based on the biological role model of an octopus

The handling of fragile, sensitive or flexible components in assembly technology and production requires grippers that are designed for gentle handling of the objects to be gripped. Suction grippers are still a widespread standard solution for this purpose. However, rising energy prices are making pneumatic grippers, which work with a central upstream compressed air supply, increasingly unattractive. The generation of the compressed air itself, the mostly leaky transmission and the relatively inefficient vacuum generation are cost drivers that many users would like to avoid. Consequently, vacuum-based gripper means are required for industrial production, which work without externally generated compressed air. At the Fraunhofer IWU, a compressed-air-free suction pad composite has been developed that enables gripping of components with a wide variety of shapes. The underlying concept is inspired by the function of the suction arms (tentacles) of an octopus. By evacuating several small volume areas, which can be individually mechanically actuated, safe and sensitive gripping of objects is possible. For the generation of the vacuum, a piston system and a principle of an artificial muscle were developed, which is controlled based on shape memory alloys.

ASSESSING AND IMPROVING COMPRESSED AIR NETWORK IN UNDERGROUND MINES (A CASE STUDY IN IRAN)

Compressed air is one of the most common methods of energy transfer in industrial and mining systems. Compressed air has numerous applications in underground mines to ensure safety (ventilation fans), carry out extraction operations (compressed air equipment and machines), and manage technical services like dewatering and the operating of spare equipment. Therefore, it is necessary to investigate the compressed air supply systems in mines to assess the sufficiency of compressed air, reduce energy consumption, and lower operating costs. Considering the significance of utilizing compressed air in underground mines, it is essential to verify the adequacy of the flow rate and permissible pressure of compressed air for all mine air consumers. This requires proper design and adjustment of the compressed air distribution network. In this paper, the compressed air network in the main compressor house of the Qaleh-Zari copper mine in Iran was investigated. To achieve this goal, the compressed air consumption in various mining operation conditions was investigated and discussed after surveying the airflow transmission lines. The pressure drops in each line were estimated as well. Regarding the results, the airflow consumption in regular mining operations is about 36 cubic meters per second. The drop in air pressure within the network lines is below the permissible limit, but the overall pressure drop is significant. In this approach, practical adjustments such as changing the diameter of the pipes, increasing the airflow pressure, and utilizing local compressors near consumers’ locations were proposed and investigated.

Justification of the air distribution system of a down-the-hole hammer with an efficient operating cycle

One method for conserving energy in the mining industry and ensuring the required pressure of compressed air in underground mining networks is to decrease the specific energy carrier consumption, particularly in the case of down-the-hole hammers. The objective of this study is to substantiate the air distribution system of an air hammer, aimed at reducing the specific consumption of compressed air. We propose a system consisting of two chambers with a constant supply of compressed air, two controllable chambers, two elastic valves on the hammer, and a valve for cutting off the supply of compressed air to the forward stroke chamber, which is controlled by the hammer’s position. This proposed configuration was employed to create two different designs for the air hammer. The operational cycle of the designed device has been numerically examined using SimulationX software and validated through experimental testing on a laboratory bench. Our calculations reveal that the suggested air distribution system, featuring controlled inlet to the backward stroke chamber, successfully achieves the stated objective. In comparison to the standard M29T hammer with nearly identical dimensions, striking power, and compressed air consumption for cleaning the borehole, the designed hammer exhibits a 53% reduction in specific energy consumption, and its electrical power usage for compressed air supply is halved. These design specifications align with both experimental results and data derived from the existing literature, confirming the accuracy of our calculation.

Semi-Empirical Models for Stack and Balance of Plant in Closed-Cathode Fuel Cell Systems for Aviation

In recent years, there has been a growing interest in utilizing hydrogen as an energy carrier across various transportation sectors, including aerospace applications. This interest stems from its unique capability to yield energy without generating direct carbon dioxide emissions. The conversion process is particularly efficient when performed in a fuel cell system. In aerospace applications, two crucial factors come into play: power-to-weight ratio and the simplicity of the powerplant. In fact, the transient behavior and control of the fuel cell are complicated by the continuously changing values of load and altitude during the flight. To meet these criteria, air-cooled open-cathode Proton Exchange Membrane (PEM) fuel cells should be the preferred choice. However, they have limitations regarding the amount of thermal power they can dissipate. Moreover, the performances of fuel cell systems are significantly worsened at high altitude operating conditions because of the lower air density. Consequently, they find suitability primarily in applications such as Unmanned Aerial Vehicles (UAVs) and Urban Air Mobility (UAM). In the case of ultralight and light aviation, liquid-cooled solutions with a separate circuit for compressed air supply are adopted. The goal of this investigation is to identify the correct simulation approach to predict the behavior of such systems under dynamic conditions, typical of their application in aerial vehicles. To this aim, a detailed review of the scientific literature has been performed, with specific reference to semi-empirical and control-oriented models of the whole fuel cell systems including not only the stack but also the complete balance of plant.

Improvement of the Prototype of the Compressed Air Foam System and its Testing

The prototype of the compressed air foam system was improved based on the evaluation of the numerical parameters obtained with the help of the developed mathematical model of the foam generation process and the pneumatic-hydraulic scheme. The prototype provides the possibility of foam generation both in autonomous mode, due to the installation of cylinders with compressed gas, and in stationary mode, due to the supply of compressed air from an external source. This allows the use of an improved model of the compressed air foam system both in stationary mode (dry pipes, gas stations, etc.) and for use on heavy and light fire trucks, which is important for large cities. Testing of the improved prototype of the system for extinguishing model fires was carried out. The system provides extinguishing of model fires of class 183 B and 144 B when using both a general-purpose foaming agent and a special film-forming foaming agent. When using a film-forming foaming agent, the extinguishing time was reduced by 1.75 times, the consumption of fire extinguishing solution by 1.47 times. But at the same time, it should be taken into account that the cost of the film-forming foaming agent Sofir (sofirafff 6 %) is more than 3.2 times the cost of the general-purpose foaming agent Sofir. The effectiveness of the improved model in extinguishing class A fires was also confirmed. The autonomous compressed air foam system ensures extinguishing of a class 4 A model fire in 90 seconds. Dry foam with a factor of 14 is noted to be more effective in extinguishing solid combustible substances.

Influence Analysis and Performance Optimization of a Pneumatic Actuator Exhaust Utilization System

Due to the loss of exhaust energy, the compressed air energy utilization efficiency in pneumatics system is low. To realize the recovery and utilization of cylinder compressed air, a new type of compressed air utilization system is proposed, and the composition and working principle of the system are introduced. According to the working process of the system, the mathematical model of the system is established by using equations such as energy equation and gas state equation. The model is simulated by MATLAB/Simulink tools, and the correctness of the mathematical model is verified by experiments. The mathematical models are converted into dimensionless models, and the main parameters affecting the system's operating characteristics are obtained through model simulation analysis. The influencing parameters are optimized by using the analytic hierarchy process and the grey correlation analysis method, and the exhaust utilization efficiency of the system is 34.7 % under the optimal parameter combination. To further utilize the compressed air expansion, the opening and closing time of the solenoid valve was controlled to study the energy-saving effect of the system. The study found that when the initial pressure of the compressed air supply tank was set to 0.5 MPa, 0.6 MPa, and 0.7 MPa, the maximum energy saving efficiency was 23.25 %, 24.99 %, and 26.12 %, respectively. When the volume of the compressed air supply tank is set to 0.8 L, 1 L, and 1.2 L, the maximum energy-saving efficiency is 30.01 %, 24.99 %, and 21.51 %, respectively. This paper provides a new technical scheme for compressed air recovery and reuse, as well as a theoretical basis for the control of subsequent compressed air utilization systems.

Design And Development of Pneumatic Actuated Robotic Arm with Multipurpose Gripper

Grippers are attached at the end of an industrial arm robot for material handling purpose. Grippers plays a major role in all pick and place application industries. Those are connected as end effectors to realize and develop a task in an industrial work floor. Pneumatic gripper works with the principle of compressed air. The gripper is connected to a compressed air supply. When air pressure is applied on the piston, the gripper gets opened while the air gets exist from the piston it gets closed. It is possible to control the force acting on the gripper by controlling the air pressure with the help of the valve. The results from these experiments demonstrate that the master-slave attitude control can be realized by using an accelerometer and a simple analytical model of the robot arm. The trajectory control also was realized for a square trajectory by using an analytical model and a compact control system. C measured one is relatively large compared with typical robot arm. This is because by a friction that is existing in a rod-less type flexible pneumatic cylinder. The control performance can be improved by reducing the friction or by improving the control scheme. Pneumatic actuators have a number of advantages over electric motors, including strength-to-weight ratio, tunable compliance at the mechanism level, robustness, as well as price. The handling of materials and mechanisms to place of objects from lower plane to higher plane and are widely found in factories and industrial manufacturing. Pneumatic actuators have a number of advantages over electric motors, including strength-to-weight ratio, tunable compliance at the mechanism level, robustness, as well as price. The handling of materials and mechanisms to place of objects from lower plane to higher plane and are widely found in factories and industrial manufacturing.

Investigation of Technical Feasibility of Hybrid Compressed Air Cogeneration Systems under Energy-Flexible Operation

The study investigates the effects of energy-flexible operation of hybrid compressed air systems in production processes with a view to efficiency and energy consumption. As energy costs become increasingly important in the economic considerations of industrial companies, integrating renewable energies necessitates the implementation of demand-side management capabilities to overcome the problem of intermittent energy production. One promising solution is hybridization, enabling energy systems to utilize multiple forms of energy. In the context of hybrid compressed air systems (CAS), it enables the use of gas, for example natural gas, hydrogen gas or biogas, and electricity for compressed air production, thus substituting electricity or gas demand on short- and long-term horizons. Advantages of such systems include the provision of energy flexibility as well as the variable supply of compressed air, process heat, and electricity through recuperation in the electric motor according to production plant consumption. However, the effects of energy-flexible operation on energy consumption and thus on the system's efficiency still needs to be fully understood. To this end, a demonstrator of a hybrid CAS cogeneration plant was built. Specific scenarios are used to analyze the effect on energy efficiency and the feasibility of energy-flexible operation. Despite slight reductions in efficiency during operation, the feasibility of operation was validated and valuable insights on further improvement were gained. With a view to the expected rising volatility in energy production, the hybrid approach represents an efficient, climate-friendly, energy-flexible, and resilient solution for compressed air production that could assist in expanding industrial demand-side management.

Development of a Large-Scale High-Speed Linear Cascade Rig for Turbine Blade Tip Heat Transfer Study

The high-speed Over-Tip-Leakage (OTL) flow has a significant impact on the aerodynamic performance of the High-Pressure Turbine (HPT) passage and generates high thermal load for the blade tip. Different tip sealing and cooling design strategies are applied to reduce the OTL loss and help turbine survive in a high temperature environment. High-speed linear cascade experimental rigs play an important role in understanding the flow physics and evaluating their performance. Multiple blades and passages are often required to maintain a reasonable flow periodicity. To match the engine representative Reynolds number and Mach number, a high-speed multi-passage cascade design inevitably demands more compressed air supply. A very large amount of heating power is also required if the engine condition wall-to-gas temperature ratio needs to be matched. In this study, a simplified 2-Passage linear cascade rig for high-speed tip heat transfer research was developed. Both the design method and the rig performance are presented. Different from existing design method to match two-dimensional blade loading, this study shows there are other design flexibilities, such as assist blade tip gap, tailboard adjustment, and profiling adjustment, to match the periodic three-dimensional OTL flow structures. The design method was validated by experimental effort. High resolution tip heat transfer coefficient distribution at stationary and rotating conditions (Rotating Mach number = 0.35) are reported. The enlarged test model can offer much more improved resolution of optical measurement near the tip region.

Effects of the ground-electrode temperature on the plasma physicochemical processes and biological inactivation functions involved in surface dielectric barrier discharge

In this work, a surface dielectric barrier discharge (SDBD) device coupled with power electronics technology was designed for precise control of the ground-electrode temperature to investigate the dynamic behavior of the physicochemical processes and biological inactivation functions involved in SDBD plasma. It was found that an increase of the electrode temperature from 30 to 210 °C reduced the breakdown voltage and increased the current pulse amplitude because the reduced electric field strength and average electron density of the SDBD plasma were consistently enhanced. The change in the plasma-chemistry mode (O3-dominant to NO x -dominant) was more sensitive to the ground-electrode temperature than that of the power density and gas temperature. O3 in the gas and liquid phases could not be detected at electrode temperatures above 90 °C, and the NO x mode almost immediately occurred after the plasma was turned on for ground-electrode temperatures of ⩾180 °C. The increase in the electrode temperature increased the acidity of the plasma-activated water and, more importantly, short-lived reactive species OH and NO were detected at electrode temperatures ⩾120 °C in the case of aqueous solutions treated directly with SDBD plasma. The biological inactivation function of the SDBD plasma, i.e. for bacterial suspensions and tumor cell cultures, was improved by about three orders of magnitude and 40% at the optimal electrode temperatures of 180 °C and 120 °C, respectively. This is an important breakthrough for development of SDBD-based biomedical devices for specific purposes on a commercial level by regulating the plasma chemistry through the ground-electrode temperature, overcoming the limitations of chamber heating and compressed air supply.

Effective energy saving techniques for the system of pneumatic gauges

Pneumatic gauges are widely used in manufacturing for inspection of external or internal dimensions of shafts or holes. Pneumatic gauges require compressed air for their operation. Usually, in the pneumatic gauges, compressed air is under use only when the work pieces are to be inspected, but due to negligence, the compressed air flows continuously through the gauges even when not required. This happens as the compressed air supply is not switched off whenever not in need. The compressor itself cannot be shut off many times as many other machineries that require compressed air may be simultaneously under operation. So, the air is continuously wasted through the nozzles provided in the pneumatic gauges. This, accounts to a huge loss of compressed air in the rest of the working hours. This loss may be reduced to a couple of hours by creating awareness, but cannot be completely eliminated. Thus, a long-term solution to the problem is necessary. The paper is aimed at discussing various solutions for reducing these losses. We can achieve the best performance for the compressed air system witha compressed air flow controller.

Experimental investigation of membrane distillation with bubble column dehumidifier system for water desalination

The performance of a new integrated system of single-stage sweeping gas membrane distillation module and a bubble column dehumidifier (SGMD-BCD) was experimentally investigated. The productivity and energy consumption of the system is evaluated under different operating conditions. The SGMD module acts as a humidifier to produce high-quality distilled and the bubble column dehumidifier is an effective condenser for improved performance. The sweeping air stream is created in two different ways; using a vacuum pump and compressed air. Results showed that the integrated system yields higher permeate flux, better gained output ratio (GOR), and lower specific thermal energy consumption (SEC) when the vacuum pump is used. Increasing the feed temperature from 50 to 80 °C increased the flux by 175%, on average. Doubling the sweeping air flow rate from 1 to 2 SCFM resulted in flux enhancement of 49% and 25% for the vacuum pump and the compressed air supply, respectively. Operating the system with the vacuum pump and without cooling the bubble column dehumidifier showed a marginal reduction in flux but resulted in significant improvements in GOR and SEC values of 0.76 and 909 kWh/m3, respectively, at an optimum dehumidifier water column height of 9.5 cm.

Numerical and experimental studies on a pressurized hybrid tubular and cavity solar air receiver using a Scheffler reflector

• Coupled optical and thermal model of a pressurized tubular and cavity solar air receiver. • Modelled the dynamic variation of concentrated solar radiation input to the receiver cavity surface. • Three-dimensional CFD analysis is performed on the hybrid receiver model. • Validation with on-sun experimental results using a Scheffler dish. • Natural convection and radiation heat loss estimation. In this study, a pressurized tubular and cavity solar air receiver is analyzed numerically, and the results are validated experimentally using a Scheffler fixed focus concentrator. Transient numerical analyses for periods similar to experimental testing duration allows realistic performance prediction of new receiver designs and help in understanding the dominant heat loss mechanisms, thus mitigating or reducing them. A coupled optical and thermal model is developed for analyzing the receiver with a novel method of capturing the spatial and temporal variation in the heat input to the receiver. The concentrated heat flux input to the receiver is defined as the product of two separate functions. The first function defines the incident radiation to the receiver as a spatially resolved flux profile on the cavity inside surface, obtained from the ray tracing algorithm. The second function captures the transience in heat input by curve-fitting the measured direct normal irradiation variation with time corresponding to the experimental testing period. Receiver heat loss modelling involves natural convection heat loss from the inside cavity surface estimated using an existing correlation, while radiation heat loss is estimated by prescribing the surface emissivity and computing the ambient view factor. A three-dimensional transient CFD analysis is performed on the hybrid receiver model under identical heating conditions as experiments to predict the flow heat transfer. The result from the numerical model is subsequently compared with on-sun experimental results obtained using a test rig equipped with a Scheffler dish for heat input and supply of compressed air as the heat transfer fluid through the receiver. The deviation between numerical and experimental results are less than 16 °C for air outlet temperature and less than 9% for the receiver thermal efficiency, thus proving the effectiveness of the coupled optical and thermal model. To account for the transient nature of the receiver heating during the on-sun experiments, the receiver thermal efficiency definition has been modified to include the thermal inertia of the receiver material. It is also observed that natural convection is the dominant heat loss mechanism for the present configuration and can significantly reduce the overall thermal efficiency of a receiver. The present numerical model incorporating an optical model of the solar field and as-measured variation of solar radiation input can be effectively used for optimizing the design of any generic concentrator-receiver system with high-pressure heat transfer fluid, with the objective of minimizing thermal losses.

Influence of Inlet Parameters on Power Characteristics of Bernoulli Gripping Devices for Industrial Robots

There is a wide variety of gripping devices with various parameters at the present stage of development of robotics. However, the existing literature about the power characteristics of pneumatic gripping devices does not provide any analysis of the different types of input parameters other than supply pressure and flow characteristics, whereas the input parameters completely determine the technical characteristics of the gripping devices of industrial robots. In particular, for pneumatic grippers, the input parameters play a crucial role in their productivity and energy efficiency. This paper fills the gap by providing a study of the impact of such parameters on the power and energy characteristics of Bernoulli ejection grippers for industrial robots, including: the parameters of the compressed air inlet design, the parameters of the fitting for compressed air supply, the diameter of the hose for compressed air supply, and the size of the vacuum zone. First, this paper presents the results of theoretical studies and finite element method for determining the distribution of pressure on the surface of an object of manipulation, which allows one to determine the lifting force of the Bernoulli gripping devices of an industrial robot. It is determined that the horizontal air flow to the capture chamber, compared with that of the vertical, should be used to ensure the maximum possible lifting force. Structures and constriction in fittings, which are used to supply compressed air to the chamber of Bernoulli gripping devices, are considered. Then, the dependencies of the influence of narrowing the fittings on the power characteristics of gripping devices are presented.

Performance parameters assessment of a pneumatic engine for low capacity commercial vehicles

In the present work, the performance evaluation of a low capacity pneumatic engine is shown, through modeling and simulation in order to identify the feasibility of its application in commercial vehicles for short distances. For the modeling of the pneumatic engine, a comprehensive approach has been used that includes the compressed air supply pipe, the cylinder compression - expansion chamber, and the intake and exhaust valves. The compressed air supply system is modeled using compressible fluid flow models. The fluid flow is considered adiabatic represented by the model known as Fanno flow (or non-isentropic) and it is assumed to be in a steady state. The flow in the opening and exhaust valves are evaluated as adiabatic and isentropic fluid, using a divergent - convergent compressible fluid model. The simulation results show that the feeding pressure and the pipe diameter have a great influence on the motor power. Also, the compression ratio has been found to have strong influence on the overall system efficiency. On the other hand, the simulations show that the initial pressure of the piston does not have a great influence on performance indicators, such as power or efficiency. However, from the results found in this work, it can be seen that the model and all the results obtained in this work can be used to design and generate an optimization model that describes a pneumatic engine proposed for commercial vehicles of low capacity and short distances.

High durability variable geometry turbine for commercial vehicle turbochargers

Abstract Transportation sector constitutes a major portion in the Green House Gas (GHG) emissions of the world. Reduction of GHG emission requires the development of highly efficient Internal Combustion Engines (ICE) which are downsized using turbochargers that provide compressed air for cleaner combustion. Variable Geometry (VG) turbochargers are widely accepted for this application because of the ability of VG turbine to function at wider flow range. This ensures the supply of compressed air at low engine speeds also. However, the interaction between stator vanes and turbine rotor has been a major issue in terms of High Cycle Fatigue (HCF) of such a turbocharger. Till now, a conservative design approach constrained the maximum rotation speed to below resonance speed for vibration mode 2. But, to achieve further downsizing it would be necessary to challenge higher rotation speeds. This paper will firstly introduce the tip-timing experiment and CFD-FEA simulations used to evaluate the HCF of VG turbine, and secondly it discusses the results of new VG turbine system which achieved safe operability even at vibration mode 3, both on simulation and experiment. The tip-timing experiment was conducted at 680°C on hot gas stand test bench with optical sensors installed circumferentially around the rotor tip. These measurements have been verified and validated with the safety factor calculated from blade surface pressure data obtained from transient rotor CFD simulations.