Compressor System Research Articles

Investigation of Surge Phenomena in a Centrifugal Compressor by 3D-1D Coupling Approach

Abstract Critical instability, such as surge phenomena, can occur at low flow rates for a compressor system, leading to flow rate fluctuations and potential damage. To study this, traditional numerical analysis requires a comprehensive approach encompassing the compressor and its piping system. This demands extensive computational resources and time due to the complexity of capturing internal flow during surge, including separation and vortex generation. To overcome these limitations, this research proposes a computational strategy combining 3D and 1D analysis for enhanced efficiency and reduced computational demands, which employs 1D analysis for more straightforward flow regions like piping and 3D analysis for the more complex compressor section. This approach is facilitated using AMESim for 1D and STAR-CCM+ for 3D simulations, enabling seamless integration and data exchange between different dimensional analyses. The method improves computational efficiency and reasonably approximates surge phenomena compared to experimental data. The 3D and 1D coupled analysis closely aligns with experimental data, providing a viable and more effective alternative method for surge analysis in compressor systems. This methodology promises to streamline the study of compressor surge phenomena, providing a practical tool for engineers and researchers.

A novel multi-objective optimization scheme of electric turbo compressor system in hydrogen fuel cell for reducing energy consumption and axial thrust

Electric turbo compressor (ETC) can recover the exhaust energy and reduce the motor power consumption, which is the future development of the air management system for fuel cell. However, the large imbalances of axial thrust and energy between the compressor and turbine leads to low reliability and efficiency of ETC. In this study, a multi-objective optimization scheme was proposed to explore the lowest ETC axial thrust and electric power consumption. First, the coupled model including compressor, turbine and axial thrust sub-models were established in MATLAB. To verify the model, computational fluid dynamics(CFD) model were established in ANSYS CFX and experimental tests were carried out. The electric power differences between the MATLAB model and experiment is within 4.36 % and the axial thrust deviations between the MATLAB and CFD model is within 5.46 %.Then, eight geometric parameters of compressor and turbine rotors are selected as independent optimization variables. NSGA-ΙΙ multi-objective optimization algorithm was adopted to search for low axial thrust and power consumption solutions. Finally, the optimization results show that the efficiency of the compressor and turbine is increased by 6.39 % and 2.75 % at design point, respectively. The electric power consumed by the motor is reduced by 7.80 % and the axial thrust of the ETC is reduced by 18.83 %.

Influence of internal bypass conditions on the double bypass matching characteristics of variable cycle high-pressure compression system

The variable cycle high-pressure compression system (VCHCS) consists of a core driven fan stage (CDFS) and a high-pressure compressor (HPC), which are crucial components for controlling the variable cycle engine's bypass ratio. However, the double bypass (DB) matching mechanism of the VCHCS remains insufficiently understood. This study focuses on investigating the DB matching characteristics of the VCHCS under different representative internal bypass conditions. The findings demonstrate that as the internal bypass conditions transition from near choke to near stall, the external bypass stability margin of the VCHCS decreases progressively, and the external bypass characteristic curve of the HPC exhibits an approximate “counter-clockwise rotation” pattern. Furthermore, the operating state of the CDFS and the redistribution of internal and external bypass flow rate, collectively determine the matching state of the compressor system. Building upon the aforementioned summarization regarding the impact of internal bypass conditions on the matching characteristics of the VCHCS, this research integrates flow field analysis to explicate the mechanism of stall under typical operating conditions. The investigation reveals that, when the internal bypass condition under design point and the external bypass condition approaches the stall boundary, an excessive accumulation of low-energy fluid occurs at the external bypass outlet guide vane, subsequently triggers the occurrence of stall. Specifically, when the internal bypass conditions under the near stall point, the predominant limitation on further elevation or reduction of external bypass back pressure lies in the extensive blockage of a massive low-energy fluid on the suction surface of the HPC second stage stator.

Design and optimization of a novel porous plate oil–gas separator

In the oil-injection compressor system, it is necessary to separate the lubricating oil by sequentially applying the mechanical separator and the separating filter element, however, the oil–gas separation filter has disadvantages such as short service life, high cost, and great environmental pollution. In this paper, a porous plate separator is proposed to achieve the coalescence of small oil droplets, and then the larger droplets can be removed by mechanical collisions driven by turbulence flow in the separator. This device is designed to be used after the primary separator, in the hope of replacing the separation filter element. The structure of the porous plate oil–gas separator is constructed through the staggered arrangement of two porous plates, and the two-phase flow characteristics in the separator are simulated through the Euler-Lagrangian method with the droplet’s behavior of collision and breakup considered. The hole diameter, hole distance, plate distance, and inlet velocity are the key parameters of the separator, and these parameters are combined through the orthogonal design method to form several different structures and working conditions. The results of range analysis and pressure difference distribution under different layers are analyzed comprehensively, so the best combination is determined in terms of particle size growth rate, oil separation efficiency, and pressure loss. The designed structure is machined, and a test bench is set up, so the performance of the porous plate separator is experimentally tested. It is found that the simulation results are in good agreement with the experimental data, and the best simulated conditions are also verified by the experiment. When the inlet velocity is 0.2 m·s−1, the optimal scheme is suggested as follows: Hole diameter = 1.5 mm; Hole distance = 3 mm; Plate distance = 1 mm; plate layers = 40.

How to Improve Fatigue Life and Residual Stress in Compressor Reeds through Shot Peening

Abstract: Numerous industrial areas involve the utilization of shot peening as a well-known surface enhancement method for increasing the fatigue life and residual stress of cyclically loaded crucial parts. This study examines the effects of shot peening on compressor reeds that can lengthen their life cycle with an accelerated rate of residual stress thereby improving reliability and performance of entire compressor system. The paper explains the principles behind shot peening, its influence on materials, and some specific advantages that it gives to thin reed compressors. Materials selection, parameters for shot peening and testing methods are described as experimental methods. Results from residual stress analysis show how much more efficient shot peening makes compressor reeds tough and reliable. Moreover, this paper provides insight into practical aspects, difficulties faced in practice and directions for further research when applying shot peeing to compressor’s reed components.

A novel robust MPC scheme established on LMI formulation for surge instability of uncertain compressor system with actuator constraint and piping acoustic

This paper presents a new control method for surge instability of the compressor system. Due to the importance of the active control approach in improving the efficiency of the compressor system, a new scheme based on the model predictive control (MPC) technique has been considered to control surge which gives the benefits of control signal optimization by considering the constraints on states and input. Because of designing a novel MPC by using of linear matrix inequality scheme, the optimization problem is solved in less time and with less complexity. The proposed method is able to consider the limitation of the close coupled valve actuator and also covers the uncertainty on the model. In addition, the developed model describes the nonlinear behaviour of the compressor system and handles the effects of the pipe on surge instability. Using Lyapunov theory, the stability of the closed-loop system under the proposed robust active controller is shown. The simulation results show the high pressure and high efficiency operation of the system under study in different operating conditions.

Development of switchless thin-plate sorption compressor and miniaturized check valves for 5 K J- T cooler

The cell of the sorption compressor developed in this paper has a thin-plate shape to accelerate the pressure swing by reducing the heating and cooling periods. Its width, height and thickness are 100 mm, 100 mm and 4.6 mm, respectively. Two identical cells filled with 22.8 g of charcoal mass are operated alternately to generate and maintain significant pressure difference for the 5 K J-T cooler with the pre-cooling temperature of 15 K. The designed nominal pressure of the high-pressure and the low-pressure parts of the J-T cooler are 1000 kPa and 196 kPa, respectively. The mass flow rate and the pressure gradient of the thin-plate sorption compressor with commercial check valves are measured experimentally. As the performance of the compressor, COP of the compressor is estimated and compared with the compressor of previous researches. Furthermore, to reduce leakage rate and thermal inertia of check valves in the compressor, miniaturized check valve is specially designed and fabricated to replace the commercial valve. When the flow direction is reversed in the valve, the leakage is passively prevented by contacting two metal surfaces at low temperature (30 K). The essential parts of the valve are critically miniaturized to reduce the overall thermal inertia of the compressor system. The cracking pressure and the leakage rate of the developed check valve and the commercial check valve are measured to compare.

End station refrigerator 2 cryoplant at Jefferson Lab

The End Station Refrigerator 2 (ESR2) cryoplant will provide cryogens to three of the four experimental halls in support of 12 GeV Continuous Electron Beam Accelerator Facility (CEBAF) experimental demands. In particular, the near-future Measurement of a Lepton-Lepton Electroweak Reaction (MOLLER) experiment requires the additional capacity provided by ESR2. This new cryoplant consists of a 4.0 kW at 4.5-Kelvin cold box and a two-stage compressor system. The cold box and compressor equipment were received from the Superconducting Super Collider (SSC) project and are being refurbished to meet Jefferson Lab’s future operating needs. The ESR2 cryoplant includes a new, 50+ m long cold transfer line, bayonet-can, utility system, and control system. The paper describes the fabrication and installation challenges faced, mitigations adopted, and future work plans for the cryoplant.

Overview and status of the PIP-II cryogenic system

The Proton Improvement Plan-II (PIP-II) is a major upgrade to the Fermilab accelerator complex, featuring a new 800-MeV Superconducting Radio-Frequency (SRF) linear accelerator (Linac) powering the accelerator complex to provide the world’s most intense high-energy neutrino beam. The PIP-II Linac consists of 23 SRF cryomodules operating at 2 K, 5 K, and 40 K temperature levels supplied by a single helium cryoplant providing 2.5 kW of cooling capacity at 2.0 K. The PIP-II cryogenic system consists of two major systems: a helium cryogenic plant and a cryogenic distribution system. The cryogenic plant includes a refrigerator cold box, a warm compressor system, and helium storage, recovery, and purification systems. The cryogenic distribution system includes a distribution box, intermediate transfer line, and a tunnel transfer line consisting of modular bayonet cans which supply and return cryogens to the cryomodules. A turnaround can is located at the end of the Linac to turnaround cryogenic flows. This paper describes the layout, design, and current status of the PIP-II cryogenic system.

Six years’ experience of the XFEL 2K operation

The European X-Ray Free Electron laser (XFEL) has successfully been operated for more than 5 years. The superconducting cavities and magnets being key components of the cryomodules constituting the XFEL linac and injector are operated at 2 K in a liquid helium bath. A four stages cold compressor system is used to return the vapor to the XFEL helium refrigerator with the capability of pumping up to 110 g/s for compensating static and dynamic heat losses at 2 K.In this paper technical challenges with regard to the cold compressor system such as availability, 2K pressure stability and contamination of the 2K circuit are summarized. Influence of hydrostatic head on operation of all cooling circuits is analyzed. Issues related to the use of some kinds of instrumentation as pressure transmitters, flow meters and level sensors are discussed. The experiment regarding the future XFEL project as doubling of safety valves is described.

Performance assessment and optimisation of a concentric two-piston compressor system for hydrogen storage

The ionic compressor has a prospective application potential for the conversion of mechanical energy into internal energy in high-pressure hydrogen as the ionic liquid can separate the metal piston and the hydrogen gas. The sloshing of the liquid inside is inevitable in such a liquid piston compressor, which has an impact on the specific energy consumption of the hydrogen compression. The thermofluid behaviour of this liquid sloshing can be effectively influenced by the baffle structure and piston trajectory. A novel concentric two-piston compressor is proposed in this paper, which has a unique structure that can act as a baffle inside and actively influences the fluid flow by adjusting the piston trajectory. The quantitative influence of key structural design factors on the compressor performance is investigated by mathematical modelling, based on which the optimal structural design was obtained by Taguchi and analysis of variance methods. Results indicate that the diameter ratio of Piston A to Piston B is the dominating factor for both the mass delivered and the specific energy consumption. With the optimal design in the structure, the specific energy consumption is found as 2328.49 kJ/kg, where the mass delivered and power consumption are observed as 21.42 kg/h and 13.86 kW, respectively.

LQTI boost pressure and EGR rate control of a diesel air charge system with eBoost assistance

Turbocharged diesel engines often suffer significant response delay due to so-called turbo-lag, especially engines with large displacement. For this reason, many technologies have been developed to reduce turbo-lag. This paper develops a coordinated control strategy for a diesel engine equipped with an eBoost (electrical compressor) system to significantly reduce turbo-lag. A multiple-input and multiple-output (MIMO) Linear Quadratic Tracking with Integral (LQTI) control strategy, along with its scheduling logic, is developed for the Ford 6.7 L 8-cylinder diesel engine equipped with a variable geometry turbocharger (VGT), exhaust gas recirculation (EGR), and added eBoost along with a bypass valve. Note that the existing production engine does not have an eBoost and bypass valve. Multiple model-based LQTI controllers were designed at different engine operational conditions based on the associated linearized models, and the control outputs are scheduled based upon the engine load condition and bypass valve position. The developed control strategy is validated in both simulation and experimental studies, and the test results show a reduction in engine response time by up to 81.36% in terms of reaching target intake manifold (boost) pressure following a load step-up, compared with the production configuration (without eBoost and bypass valve) with no significant impact on NOx emissions.

Fostering solar hybrid cooling systems in MENA region: A techno-economic and emission reduction assessment

Solar driven cooling system is a promising and sustainable substitute for conventional cooling systems to soften the impact of energy deficit and environmental degradation. In this study, a solar hybrid cooling system for an institutional building is investigated, which combines solar photovoltaic (PV) technology with traditional vapor compression systems and/or absorption cooling systems. The performance of the proposed solar hybrid cooling system is simulated and compared at four (04) locations in Middle East and North Africa (MENA) region: Riyadh (Saudia Arabia), Dubai (United Arab Emirates), Doha (Qatar), and Jaww (Bahrain), with different cooling system configurations from technical, economic, and environmental standpoints. The simulation findings show that the solar driven absorption chiller reduces the maximum CO2 emissions by 42.7% in Riyadh, while the solar driven compressor system gives a maximum Greenhouse gas emissions reduction (99.1%) for the location of Dubai. To determine the most practical design in terms of economics, metrics such as net present value, payback, and benefit–cost ratio (BCR) and several cooling scenarios are also rigorously studied. According to model findings, the solar absorption cooling system presented the most feasible scenario with the shortest payback of 5.8 years, the highest internal rate of return (IRR) of 38.8%, and BCR of 5.4% for the location of Dubai, and the same trend holds for all other locations. Conversely, the solar-powered vapor compression system was the least suitable option for Riyadh city, with the longest payback period of 21.9 years, the lowest IRR of 2.4, and a BCR of −0.06. In addition, optimization results show that ground mounted PV systems outperform building integrated PV (BIPV) systems owing to their higher capacity factor: 21% in case of PV and 12.8% in case of BIPV systems.

Energy analysis of a simple PV/T system for heating using a variable speed vapor compressor system

The use of photovoltaic/thermal (PV/T) modules reduces the losses in the photovoltaic cells and, in addition, uses the waste heat in the panel. This paper presents the simulation results of a PV/T system for domestic hot water supply using a vapor compression system during the four seasons of the year in the conditions of Salamanca, Mexico. The results obtained from the simulation indicate that the cooling of the panel causes an increase of approximately 7% in PV efficiency. During the spring, when there is greater solar radiation and, therefore, greater electrical power generation, despite the average temperature of around 36 °C, the lowest efficiency is found. On the other hand, the highest efficiency is achieved in winter, reaching up to 22%. As for the performance coefficient, the highest value is observed during the spring, with a coefficient of performance (COP) of 6.63, while the lowest value is recorded in summer, with a COP of 5.11. It is concluded that this system can satisfy the domestic hot water demand for the conditions under study.

Model-based MIN/MAX override control of centrifugal compressor systems

We propose an application-oriented nonlinear control approach for centrifugal compressors, tailored to meet requirements of industrial applications such as variable process demands and adherence to operational constraints, for instance surge avoidance. Our compressor model modifies an approach of Gravdahl and Egeland by including key features of an industrial setting. In particular, it takes into account the joint action of adjustable positions of the guide vane and the blow-off valve, while compensating variable disturbances introduced by the process valve. Moreover, the modified model is also valid for higher differential pressures across the compressor. By integrating the nonlinear output regulation framework with MIN/MAX-override control, we enable trajectory tracking within specified state constraints. Additionally, we analyze the switching scheme and give a proof of practical stability of the closed-loop MIMO system using the corresponding switched and impulsive error system. The effectiveness of the override control is demonstrated by typical scenarios in process control such as discharge pressure control, anti-surge control, and maximum discharge pressure limitation.

Surge and stall instabilities finite-time control of nonlinear uncertain-disturbed compression system by using a novel robust approach

This paper describes a new approach to control stall and surge instabilities in the compressor system by using of finite time backstepping-based adaptive sliding mode method. The most important innovation of this study is to provide a finite time adaptive control method to simultaneously prevent the stall and surge instabilities in a compressor system in the presence of disturbance and uncertainty in the compressor characteristic curve as well as the throttle valve. The disturbance and uncertainty issues are covered by a robust sliding mode control and the gain coefficients of this controller as well as the estimation of uncertain terms are obtained by using the adaptive method. The Lyapunov stability criterion is used to evaluate the finite-time stability of the closed-loop system. The performance of the proposed method is compared with other literature methods through simulation in Matlab. The simulation results show that the proposed controller is better than the existing methods in terms of surge preventing and robustness against uncertainty and disturbance.

Collaborative Optimization of Phononic Crystal Pipe Based on Revolving Helmholtz Resonators for Air Compressor System in FCEVs

Collaborative Optimization of Phononic Crystal Pipe Based on Revolving Helmholtz Resonators for Air Compressor System in FCEVs

Effects of operating parameters on the performance of an embedded two-piston compressor system for green hydrogen

The hydrogen compressor is a key component in the refuelling station. As one type of hydrogen compressor, the ionic compressor applied in the refuelling station is essentially a liquid piston compressor. The structure and operating condition would significantly influence the system efficiency of the liquid piston compressor. This paper investigated the impact of three key operating factors on the compressor performance of a novel embedded two-piston compressor, based on which the optimal operating values were identified by the Taguchi method when the hydrogen was compressed from 12 to 45 MPa. It was revealed that the movement time ratio of Piston A was the dominating factor for the power consumption and specific consumption while the upward time ratio of Piston B was the most influential parameter for the mass delivered. The optimal combination was 0.4 for the movement time ratio of Piston A, 0.45 for the upward time ratio of Piston A and 0.5 for the upward time ratio of Piston B. Under the predicted optimal operating conditions, the lowest specific energy consumption was obtained as 2733.75 kJ/kg.

Fault diagnosis of reciprocating compressor using Teager-Kaiser energy operator and envelope spectral feature extraction

This paper proposed and implemented the Teager-Kaiser energy operator (TKEO) and envelope spectral analysis techniques for the fault detection of discharge valves of a reciprocating compressor. Based on the extraction of fault features, the instantaneous frequency and amplitude of the signals due to the discharged valve based on energy identification can be effectively characterized by the TKEO that was used to identify the characteristic fault signals accurately. The synthesized signal is processed by envelope spectral analysis and TKEO, which can extract the characteristic signal and eliminate the noise. The experimental design is verified experimentally through different reciprocating compressor gas valve conditions. The simulation results verify the feasibility of the proposed method. The experimental verification is carried out through the measurement signals of the six-cylinder reciprocating compressor under different valve operating conditions. TKEO can remove background noise to obtain reciprocating compressor fault feature signals. Feature extraction is based on TKEO and envelope spectra for fault detection of reciprocating compressors. It is expected to reduce the errors produced by traditional manual fault diagnosis methods and improve the accuracy and efficiency of fault diagnosis. The research results of vibration fault feature extraction using TKEO can be used as the basis for fault diagnosis of the reciprocating compressor system.

COMPARATIVE ANALYSIS OF PRESSURE AND FLOW CHARACTERISTICS IN BASIC AND MODIFIED AIR COMPRESSOR PIPELINE USING COMPUTATIONAL FLUID DYNAMICS IN POWER PLANT TANJUNG ENIM 3X10 MW

Air compressor plays a crucial role by converting electrical energy into kinetic energy in the form of compressed air. This study specifically concentrates on assessing the performance of two compressors that operate alternately, with one compressor in standby mode. Unfortunately, compressor unit #1 faced issues with its drying system, rendering it unable to function within the current pipe network. In order to rectify this, proposed modifications to the pipeline network are introduced and scrutinized. To analyze these modifications, Computational Fluid Dynamics (CFD) is employed to evaluate and compare pressure and flow characteristics in both the existing and modified pipe configurations. The CFD analysis utilizes computer engineering software, with SolidWorks serving as the primary modeling and simulation tool. The assumption is made that the Reynolds number corresponds to laminar flow, factoring in pipe diameter and compressor volume rate.The resulting CFD data offers valuable insights into pressure and velocity distributions within the existing and modified pipeline networks. During the pressure simulation, surface pressure and output on both standard and modified pipes exhibit relatively similar pressure values at 7 bar. However, in the air velocity simulation, surfaces of standard and modified pipes maintain a consistent range of 0 – 5 mm/s. Notably, from the pipe output side, air velocity in standard and modified pipes displays distinct speed contours. Standard pipes show the highest speed between 0.25 – 0.38 mm/s, whereas modified pipes exhibit the highest speed within the range of 0.15 – 0.2 mm/s. This study aims to provide a comprehensive evaluation of the proposed modifications, seeking to enhance understanding of the fluid dynamics within air compressor systems. The outcomes of this research have the potential to contribute significantly to optimizing the performance and efficiency of these systems, thereby offering benefits across various industrial applications.