Compressor System Research Articles

Assessment of Engine Operability and Overall Performance for Parallel Hybrid Electric Propulsion Systems for a Single-Aisle Aircraft

Abstract This paper aims to assess the gas turbine operability and overall hybrid electric propulsion system (HEPS) performance for a parallel configuration applied to a 150 passenger single-aisle aircraft. Two arrangements are considered: one where the low-pressure (LP) shaft is boosted and one where the high-pressure (HP) shaft is boosted. For identifying limits in the hybridization strategy, steady-state and transient operation are considered, and the hybridization effect on compressor operability is determined. Having established the electric power on-take limits with respect to gas turbine operation, the systems performance at aircraft level is quantified for the relevant cases. Different power management strategies (PMS) are applied for the two arrangements and for different power degrees of hybridization. The results indicate that despite the fact that pollutant emission and fuel consumption may improve for hybrid propulsion, this comes at the cost of reduced payload and operability margins. Boosting the LP shaft may give the highest engine performance benefits but with a significant weight penalty, while the LP compressor system operability is negatively affected. On the other hand, boosting the HP shaft provides lower engine performance benefits but with smaller weight penalty and with less operability concerns.

Design and Performance Analysis of Anti-Surge Control Mechanism for Compressor System using Neural Networks

The compressor system is caused by the surge, which is an instability occurrence in most gas-process and oil industries. These issues are solved by using a recycle valve that avoids the surge and provides higher mass flow in the compressor system. An advanced controller-based anti-surge control mechanism is a need in the compressor system to improve the stability and surge issues. In this manuscript, an efficient, Neural-network predictive controller (NNPC) based variable speed compressor recycle system is modeled with an anti-surge control mechanism. When the mass flow is deficient, the recycle system is introduced, acts as a safety system, and feeds the compressed gas back to the upstream system. The different controllers like Proportional Integral Derivative (PID) controller, Fuzzy logic controller (FLC), and Neuro-fuzzy controller (NFC) based anti-surge control mechanism are also used in Compressor recycle system to compare the stability and performance metrics with NNPC. The NNPC based compressor system provides a better operating position and dynamic response with less error than other controllers-based compressor systems.

И. Ивкович-Кихич, М. Рид, Ш. Рэйн, А. Ковачевич «Компрессоры и их системы». Итоги конференции = I. Ivkovic-Kihic, M. Read, Sh. Rane, A. Kovacevic «Compressors and their systems». Post conference report / пер. с англ. М. А. Федоровой

The article presents an overview report of the 12th International Conference on Compressors and their systems which was held in a hybrid format from September 6 to 8, 2022 in the City, University of London, UK. At this prestigious scientific and educational forum, within the framework of the plenary session, world experts made reports in the field of compressor technology and de-carbonization, as well as presentations at several technical and panel sessions on such topics as screw, scroll, vane and piston compressors; compressor systems and their diagnostic and control systems; turbo-machines; mathematical modeling and optimization of compressors, expanders and their systems. In addition, within the framework of the conference, a traditional short training course and a Forum on CFD (gas dynamic calculations) in rotary positive displacement machines were held. The introductory session was devoted to the basics of CFD implementation using the finite volume method. New studies in the field of CFD in rotary volumetric machines were presented, including those based on such programmes as ANSYS Forte and OpenFOAM. Complex modeling approaches, such as SCORG and GT-Suite, also attracted the attention of participants. Information about the next conference on Compressors and their systems, which will be held in 2023, is presented.

Research on Energy Conservation Technology of Pre-Cooling Air Compressor System

Research on Energy Conservation Technology of Pre-Cooling Air Compressor System

Dynamic Evaluation: Centrifugal Compressor’s Operation in Determining Anti-Surge Controller

Anti-surging is developed for a compressor system consisting of a booster compressor and a high-pressure compressor in a serial circuit. This evaluation presented 6 options of anti-surge systems with variations of the number of Anti-surge Valve (ASV) and its combination with the addition of a Hot Gas Bypass Valve (HGBV) and Cold Gas Bypass Valve (CGBV). From the model evaluation, the option that involves a special ASV (dedicated) for each compressor and coupled with a dedicated CGBV or HGBV is the best because the compressor can be back to normal in less than 1 second (maximum time to return to normal condition is 3 seconds. Referring to these options, a dedicated ASV for each compressor provides more benefits to the security of compressor operation. However, the most appropriate option in the field will return to the issue of cost or ease of modification. For facilities that are running (brownfield), the use of tools that already exist in the field and do a little modification is the most appropriate option, while for the new facility (grassroots project), the single ASV for a compressor circuit is the most optimum as it only involves minimum equipment and configuration as simple as possible piping/instrumentation.

Adjustable Speed Control and Damping Analysis of Torsional Vibrations in VSD Compressor Systems

This paper proposes a model-based two-degree-of-freedom (2DOF) speed control for a medium voltage (MV) variable speed drive (VSD) connected to a centrifugal compressor (CC) train. Torsional mode excitations in the drive shaft due to converter switching behaviour are considered. An effective description of the harmonics transfer is proposed. The tuning strategy aims to optimize the tracking behaviour of the step and ramp command, taking care of critical speed excitations. The stability of the closed-loop dynamics against time delay and drive parameter variations are studied by means of Nyquist diagrams and time-domain simulations. A descriptive method for the process damping behaviour is proposed. The control strategy is evaluated through simulations as well as an experimental setup, based on a hardware in the loop (HIL) in a master–slave configuration.

Changes in self-image after pectus carinatum brace treatment

Background/PurposePectus carinatum (PC) is a chest wall deformity resulting in anterior protrusion of the chest. PC does not typically result in significant physical or cardiopulmonary symptoms, but patients with this condition can experience a disturbed body image, lower self-esteem and reduced quality of life. The purpose of this study was to investigate the relationship between self-image and non-surgical correction of PC using a brace. MethodsThis study was a descriptive, pre-post survey design. The sample included children ages 11 to <18 years undergoing PC treatment with the dynamic compressor system. Subjects completed the modified Pectus Excavatum Evaluation Questionnaire (mPEEQ) at the onset of bracing and again once PC correction was completed. ResultsNinety-seven subjects were enrolled at the time of bracing, and 41 achieved correction and took the second survey. The mean age was 14 years and 80% were male. There was a statistically significant (p<0.001) improvement in body self-image between the first and second surveys. ConclusionsNon-surgical correction of PC with the dynamic compressor system resulted in an improvement in the self-image of children. Prognosis studyLevel of Evidence II

Compressor Stability at Pulsating Condition Via Gas Dynamics Responses Analysis

Abstract The compressor is operated at unsteady exit conditions in many scenarios such as the instability of combustion in gas turbine and denotation engine. The aerodynamic stability of the compressor is inevitably influenced by the unsteady operating environment. In this paper, a one-dimensional (1D) model that combines pulsation and unsteady responses of the compressor is developed to investigate the stability of the compressor system. The results show that the onset of surge and the transient responses of the compressor during surge are well predicted by the method. The amplitude of the component at surge frequency obtained by fast Fourier transformation (FFT) method is applied as a criterion to quantitively evaluate the onset and the strength of the surge. Compressor stability is enhanced at pulsating conditions due to the interaction between forced oscillation of pulsation and self-sustained oscillation of surge. An analytical model is established to understand the mechanism of the enhancement of compressor stability under pulsation. The change of total energy of the compressing system is proposed to evaluate the influence of pulsating conditions. Specifically, the energy change is reduced for pulsation conditions due to two aspects: the lower slope of compressor characteristic curve due to the lag-effect of compressor responses and the higher energy dissipation due to the nonlinear throttling effect.

Development of High-Altitude Hybrid Fan Centrifugal Compressor System for Turbochargers and Utilization of AI to Improve Combustor Performance

This opinion paper focus on the belief of the authors, that adding a fan or pre-compression stage in front of a centrifugal impeller typically found in commercial turbochargers has the potential to increase the overall pressure ratio of the turbocharger, which help with high-altitude operation. Additionally, this paper address conviction of the authors that the utilization of artificial intelligence and data science will improve combustor performance.&nbsp; The focus is on the development of high-altitude hybrid fan centrifugal and compressor system for turbochargers. Current attainable flight times of Unmanned Aerial Vehicles (UAVs) at high altitudes greatly hinder potential mission capabilities. Specifically, the US Army’s small UAVs are propelled by automotive compression-ignition (CI) engines, which deliver the required high efficiency and low fuel consumption but lack the ability to ingest an adequate mass flow rate of low-density air into their compression cylinders at high altitudes. A hybrid fan- centrifugal compressor system will be developed and integrated onto these UAV engines to provide the air mass flow rate necessary to operate at 60% of maximum sea-level power while at 30,000 feet altitude; thus, reducing the hindrance of high altitude environmental factors on UAV missions. The combined system will be integrated on a dual shaft to allow for fan and compressor to rotate at different speeds. Dual shafts are, typically, used in turbojet engines for combined fan and axial flow compressors for delivering large air mass flow. This hybrid fan-centrifugal compressor system will offer higher pressure and mass flow rate to the current Army UAV engines than standard turbochargers, while maintaining simplicity and manufacturability.

Operational optimisation of a novel dual-piston linear compressor: Simulation and experiment

A novel dual-piston linear compressor consisting of two piston-cylinder assemblies and a linear electric motor was constructed. To explore the performance of the dual-piston linear compressor, a numerical model that contains a thermodynamic sub-model, dynamic sub-model, three-phase linear motor sub-module, and control system sub-model was built. Several piston trajectories and different operating conditions were assessed to investigate the performance of the dual piston linear compressor. Results from both the simulation and experiments indicate that the system with the triangle curve trajectory exhibits the best performance. The output characteristics (mass flow rate, motor efficiency, mechanical efficiency, and overall efficiency) depend heavily on the operating frequency and the stroke of the piston. For the dual-piston linear compressor system that was designed, the overall efficiency can reach up to 57.59% when the system works at a frequency of 12 Hz and a stroke of 26 mm.

Dynamic Analysis for a Reciprocating Compressor System with Clearance Fault

In order to explore the failure mechanism of a reciprocating compressor system with clearance fault, we implemented a computational framework whereby a simulation model of the mechanism is established using ADAMS software in this paper, and a typical reciprocating compressor model is introduced to validate the design model. In this work, the joint clearance faults between the crankshaft and linkage, between the linkage and crosshead, and in both locations are taken into account computationally. These faults are one of the major causes of vibration. Through dynamic calculation and analysis of a system with clearance fault, the simulated results show that these clearance faults directly influence the vibration. The larger the gap size, the more severe the vibration and the higher the amplitude of the vibration. Furthermore, the clearance number also affects the vibration greatly.

Robust active finite-time control of gas compressor system surge in the presence of unmatched disturbance and uncertainty

Active and robust control of surge instability is a special necessity for optimal and safe operation of centrifugal compressors, and for the purpose, this article presents a new hybrid scheme based on fuzzy and terminal sliding mode methods. The Greitzer model is used to design a novel controller when the disturbance instability in the flow and pressure alike the uncertainity in the compressor characteristic curve and throttle valve are embedded in it. The fuzzy approximator is used to estimate the effects of parametric uncertainty and the nonlinear terms, and the robustness of the proposed method is guaranteed using the terminal sliding mode control method. The Lyapunov criterion is utilized to verify the finite-time stability of the closed-loop system. The performance of the presented method is compared with other methods in the literature through simulations in MATLAB software. The results suggest that our designed controller outperforms the existing ones in terms of surge prevention and robustness against unmatched uncertainties and disturbances.

Remote treatment of pectus carinatum (Telepectus) during the COVID-19 pandemic

Background/PurposeTo report telemedicine's feasibility and satisfaction rates for treating patients with pectus carinatum using a dynamic compressor system. We analyzed treatment adherence in comparison with the previous, non-pandemic year. Materials and methodsRetrospective analysis including patients with pectus carinatum under treatment with a dynamic compressor system using telemedicine at the chest wall centers from two hospitals, private and public, between April and July 2020. A free video conference platform for teleconsultations was employed. We evaluated the incidence of pectus cases with telemedicine, the number of dynamic compressor system prescriptions, the number of patients in the correction phase, and the number who ended treatment. To assess adherence, we compared our cohort with an in-person cohort during the same time frame of the previous, non-pandemic year. In addition, we performed a patient satisfaction survey comprising questions related to socioeconomic status, the likeability of telemedicine, simplicity of modification of the system, and desire to continue with telepectus after the pandemic. ResultsOne hundred and thirty-six telepectus consultations were performed in 76 patients. During this time frame, 15 patients started using the dynamic compressor system. Compared to the previous, non-pandemic year, the number of consultations per patient was similar (2019: 1.92 ± 1 .0 vs. 2020: 1.79 ± 0.8, p = 0.32), and there was a significant reduction in the number of dropouts with the use of telemedicine (9% vs. 1%, p = 0.025). Fifty-nine patients answered the satisfaction survey. All of them solved their doubts through telemedicine. Overall, 95% found telemedicine comfortable. Of note, those with a lower income evidenced the highest intention in continuing with telemedicine. ConclusionsWe demonstrated the feasibility of remote care of patients with pectus carinatum using a dynamic compressor system with a similar frequency of consultations compared to in-person medical care. Telepectus patients revealed a high rate of satisfaction irrespective of their socioeconomic status. Level of evidenceIV. Type of studyRetrospective study.

Sistem Monitoring Instrument Air Compressor (IAC) berbasis SCADA dengan Komunikasi Modbus RTU RS-485

PLTU Pacitan adalah salah satu pembangkit listrik di Jawa Timur yang memiliki kapasitas 2 x 315 MW yang dibangun pemerintah pada Fast Track Program 1. Instrument Air Compressor (IAC) adalah salah satu peralatan bantu di PLTU Pacitan yang berfungsi sebagai suplai udara ke sistem pneumatik seluruh plant. Namun, peralatan ini tidak bisa dimonitor oleh operator Central Control Room (CCR) dengan maksimal. Parameter yang dapat dikontrol sangat terbatas. Hal ini dikarenakan terbatasnya jumlah terminal Field Bus Module (FBM) yang tersedia. Rumusan masalah adalah bagaimana cara membuat modul komunikasi untuk menampilkan parameter Instrument Air Compressor System ke display HMI operator CCR secara real time. Tujuan dari perancangan alat ini adalah membuat modul komunikasi yang aman dan handal untuk menampilkan semua parameter Instrument Air Compressor yang ada dilokal tampil di display komputer CCR. Metode yang digunakan adalah pengontrolan dan pemantauan parameter ditransmisikan dari lapangan ke CCR menggunakan komunikasi serial protokol modbus RS485. Untuk meningkatkan pengelolaaan peralatan tidak hanya dikontrol dan dimonitor tetapi juga menampilkan fault alarm untuk mengingatkan operator bahwa peralatan mengalami ketidaknormalan. Perancangan prototype mengunakan komputer sebagai HMI dan arduino nano sebagai mikrokontroller. Manfaat dari perancangan modul komunikasi ini adalah mengganti peran FBM yang jumlah terminal input dan output yang terbatas dan memiliki harga yang mahal serta meningkatkan kehandalan Instrument Air Compressor System.

An Enhanced Failure Mode Effect Analysis-Based Risk Assessment for Subsea Compressor Systems

Abstract An enhanced failure mode effect analysis (FMEA) based risk assessment for subsea compressor systems was proposed in this study. The enhanced model was established using a combination of fuzzy analytic hierarchy process (FAHP), fuzzy comprehensive evaluation, and FMEA. Different from the traditional FMEA model, the model improved the capability to identify system faults and to further measure the risk of a subsea compressor system through effective qualitative and quantitative analyses. A case study was then conducted to demonstrate the capability of the developed method in a complete risk assessment for a subsea compressor system and the subsystems and subcomponents with low reliabilities were identified. Comparing the enhanced model with previous models, it is found that the potential risks of some components are changed, and the components with higher potential risks in the system are identified. Sensitivity analysis to investigate the impact of parameters of subcomponents on system reliability was also performed.

Finite-time active fuzzy sliding mode approach for deep surge control in nonlinear disturbed compressor system with uncertainty in charactrisitic curve

In this paper, a novel active control approach is designed for surge instability in the compressor system using the finite-time fuzzy sliding mode scheme. The primary novelty of this study lies in the development of a finite-time fuzzy sliding mode control for the surge instability in a compressor system in the presence of disturbance and uncertainty in the characteristic curve of the compressor and also throttle valve. To ensure the stability of the closed-loop system in Lyapunov's concept, a finite time active control method is proposed based on fuzzy estimation method and robust adaptive and sliding mode methods. Achieving finite time stability and rapid elimination of deep surge instability occurs through a fast sliding mode design, while fuzzy and adaptive techniques are used to estimate uncertainty and nonlinear terms, as well as to obtain optimal estimation weights. The simulation results in MATLAB environment and comparison show that the suggested method provides better quality control in terms of surge suppression, robustness, and overcoming uncertainty and disturbance effects.

Essential design criteria for safe and efficient operation of an LNG boil-off gas reliquefier under deteriorated performance of system components

Reverse Brayton cycle (RBC) working with nitrogen is used to reliquefy the boil-off gas (BOG) generated in LNG storage tanks. The reliquefier consumes relatively low power if the heat exchanger surface area and the operating parameters are optimally chosen. However, these parameters depend on the isentropic efficiencies of the compressors and turbine that show degradation over years of operation. This paper attempts to find a way to maintain efficient and safe operation of the system even with deteriorated efficiencies of compressor and turbine. The analysis shows that while deterioration of compression system can be made up by applications of variable frequency drive and inlet guide vanes keeping the reliquefaction quantity unaltered, the deterioration of turbine efficiency demands that the pressure ratio of the compressor system should be higher. If appropriate flexibility is incorporated right at the design stage, a reliquefier can be re-adjusted to mitigate the system deterioration. If the isentropic efficiency turbine deteriorates from 90% to 75%, the pressure ratio of nitrogen compressor has to be increased from 3.7 to 4.7 to mitigate increased power input to the reliquefier by as much as 310 kW for a ship carrying 266,000 m3 of LNG.

Comparative analysis of working fluids for efficient waste heat recovery

The paper analyzes the implementation of plants with an organic Rankine cycle (ORC) on the example of the circuit of the regenerative gas turbine unit and exhaust gas recovery system of the compressor system of the gas-compressor unit. The theoretically achievable values of power generated by the ORC-installations are determined. A criterion is presented for comparing the working fluids according to the efficiency of use in ORC-installations. To evaluate the overall characteristics of the system, the parameters of heat exchangers for air and water cooling were determined. As a result, it is concluded that the use of ORC-installations allows to utilize up to 23% of the heat of exhaust gases (convert into useful work).

USE OF VIRAL FILTER TO REDUCE EXPOSURE TO EXHALED AEROSOL DOES NOT AFFECT METHACHOLINE DOSE DELIVERY DURING BRONCHOPROVOCATION TESTING

TOPIC: Respiratory Care TYPE: Original Investigations PURPOSE: Methacholine challenge testing (MCT) is a common bronchoprovocation technique used to assess airway hyperresponsiveness. Current ERS guidelines recommend that measures should be taken to minimize technician exposure to methacholine aerosol, with added infection control concerns in the context of the ongoing COVID-19 pandemic. We previously demonstrated that the addition of a viral filter to the nebulizer exhalation limb reduced expelled particle concentrations by 77-91% during MCT. Our aim was to evaluate whether this modification resulted in a change in the delivered dose of methacholine. METHODS: Following published industry testing standards for MCT, we connected a Hamilton-G5 mechanical ventilator and Michigan lung simulator in series with respiratory rate 15 breaths/min, tidal volume (VT) 500 mL, I:E ratio 1:1 with a sinusoidal waveform. We compared methacholine dose delivery using the Hudson MicroMist and AeroEclipse II BAN nebulizers powered by either a dry gas source at 50 psi and 4.5 L/min or the Ombra compressor system, in addition to our current MCT protocol which utilizes Hudson MicroMist nebulizer with KoKo dosimeter (3 breaths). A filter placed in line between the nebulizer and test lung was weighed before and after 1 minute of nebulized methacholine delivery. Mean inhaled mass was calculated from three trials of each method with and without a viral filter on the exhalation limb. Dose delivery was calculated by multiplying the mean inhaled mass by the respirable fraction (particles < 5 µm) and inhalation time. Unpaired t-test was used to compare methacholine dose delivery with and without viral filter placement. Due to multiple independent comparisons, Bonferroni correction was used and alpha level was set at 0.01. RESULTS: The addition of a viral filter did not significantly affect methacholine dose delivery across all devices tested. Using the 50 psi dry gas source, dose delivered with the Hudson MicroMist did not differ with (461.0 µg) or without (307.8 µg) a viral filter (P=0.11) or with the AeroEclipse II BAN with (580.8 µg) or without (678.4) a viral filter (P=0.59). Using the Ombra compressor, dose delivered with the Hudson MicroMist did not differ with (1063.3 µg) or without (947.5 µg) a viral filter (P=0.026) or with AeroEclipse II BAN with (843.8 µg) or without (648.3) viral filter (P=0.42). Dose delivery did not differ significantly when using the KoKo dosimeter and Hudson MicroMist with or without a viral filter (P=0.20) using a 3-breath protocol. CONCLUSIONS: The addition of a viral filter to the nebulizer expiratory limb did not result in a significant change in the in the delivered dose of methacholine. CLINICAL IMPLICATIONS: Based on these findings, use of a viral filter to limit the concentration of expelled aerosol during MCT should be considered to improve pulmonary function technician safety and potentially reduce the risk of infectious exposure during the ongoing COVID-19 pandemic. DISCLOSURES: No relevant relationships by Kaiser Lim, source=Web Response no disclosure submitted for todd meyer; No relevant relationships by Alexander Niven, source=Web Response No relevant relationships by Paul Scanlon, source=Web Response No relevant relationships by Yosuf Subat, source=Web Response No relevant relationships by Keith Torgerud, source=Web Response

Tailored Centrifugal Turbomachinery for Electric Fuel Cell Turbocharger

Hydrogen fuel cell technology is identified as one option for allowing efficient vehicular propulsion with the least environmental impact on the path to a carbon-free society. Since more than 20 years, IHI is providing charging systems for stationary fuel cell applications and since 2004 for mobile fuel cell applications. The power density of fuel cells substantially increases if the system is pressurized. However, contaminants from fuel cell system components like structural materials, lubricants, adhesives, sealants, and hoses have been shown to affect the performance and durability of fuel cells. Therefore, the charging system that increases the pressure and the power density of the stacks inevitably needs to be oil-free. For this reason, gas bearings are applied to support the rotor of a fuel cell turbocharger. It furthermore comprises a turbine, a compressor, and, on the same shaft, an electric motor. The turbine utilizes the exhaust energy of the stack to support the compressor and hence lower the required electric power of the air supply system. The presented paper provides an overview of the fuel cell turbocharger technology. Detailed performance investigations show that a single-stage compressor with turbine is more efficient compared to a two-stage compressor system with intercooler. The turbine can provide more than 30% of the required compressor power. Hence, it substantially increases the system efficiency. It is also shown that a fixed geometry turbine design is appropriate for most applications. The compressor is of a low specific speed type with a vaneless diffuser. It is optimized for operating conditions of fuel cell systems, which typically require pressure ratios in the range of 3.0.