Compressor Applications Research Articles

Performance prediction and design optimization of a transonic rotor based on deep transfer learning

Deep transfer learning is frequently employed to address the challenges arising from limited or hard-to-obtain training data in the target domain, but its application in axial compressors has been scarcely explored thus far. In this paper, a multi-objective optimization framework of a transonic rotor is established using deep transfer learning. This framework first pre-trains deep neural networks based on the peak efficiency condition of 100% design speed and then fine-tunes the networks to predict the performance of off-design conditions based on the small training dataset. Finally, the design optimization of the transonic rotor is carried out through non-dominated sorting genetic algorithm II. Compared to neural networks that are trained directly, transfer learning models can achieve higher prediction accuracy, particularly in scenarios with small training datasets. This is because the pre-trained weights can offer a better initial state for transfer learning models. Moreover, transfer learning models can use fewer samples to obtain an approximate Pareto front, making the optimized rotor increase the isentropic efficiency at both peak efficiency and high loading conditions. The efficiency improvement of the optimized rotor is attributed to the reduction of the loss associated with the tip leakage flow by adjusting the tip loading distribution. Overall, this study fully demonstrates the effectiveness of transfer learning in predicting compressor performance, which provides a promising approach to solving high-cost compressor design problems.

Experimental study on system characteristics of vapor compression refrigeration system using small-scale, gas-bearing, oil-free centrifugal compressor

Small-scale refrigeration centrifugal compressors hold the potential for superior efficiency compared to currently used positive displacement compressors. However, traditionally, centrifugal compressors have been employed in large refrigeration systems with cooling capacity of several hundred kilowatts or more. Conversely, the application of small-scale centrifugal compressors in smaller refrigeration systems, with cooling capacity in the tens of kilowatts, has largely remained theoretical, lacking practical experimental studies. For a better understanding of the operational characteristics of such systems, this study constructed a 45 kW R245fa refrigeration system test bench based on the small-scale oil-free centrifugal compressor utilizing gas foil bearings. The experimental investigation analyzed the impact of refrigerant charge amount, compressor speed, and coolant flow rate on system performance. Results indicate that the system achieves its peak cooling capacity of 49.73 kW with a system COP of 3.64 at 65,000 rpm. Moreover, at 50,000 rpm, the system demonstrates its highest system COP of 4.23 with a cooling capacity of 26.07 kW. In comparison to traditional positive displacement compressor refrigeration systems, it exhibits higher energy efficiency. Additional simulation studies were conducted to evaluate the effects of substituting R1233zd(E) for R245fa on the system performance and to assess the feasibility of such a substitution.

Exploring the Impact of HFO-1234YF Refrigerant on the Tribological Properties of Advanced Polymeric Coatings

Abstract The global focus has shifted toward mitigating the impact of global warming, particularly in the air-conditioning and refrigeration sectors, where there is a strong emphasis on the use of environmentally friendly refrigerants. One such refrigerant that has gained increased usage is HFO-1234yf. The increasing use of HFO-1234yf as a refrigerant in automobile air-conditioning compressors presents new challenges in terms of material compatibility. In this research, we investigate the impact of HFO-1234yf in automobile compressor applications by comparing the tribological results of the same materials in air. We conducted tribological experiments under starved lubrication conditions using polyetheretherketone (PEEK)/polytetrafluoroethylene (PTFE) and aromatic thermosetting co-polyesters (ATSP)/PTFE-coated aluminum alloy samples. We found that the ATSP/PTFE coatings perform exceptionally well irrespective of the atmosphere, while the presence of HFO-1234yf refrigerant adversely affects the tribological performance of the PEEK/PTFE coatings, citing the lack of a stable tribofilm formation. These findings offer valuable insights for the development of materials and lubricants that are compatible with HFO-1234yf refrigerant applications.

Investigation of aerodynamic effects and dominant design variables of cavity squealer-tip in three-dimensional performance of a centrifugal compressor

Enhancing the performance of turbomachines has been a longstanding area of interest, with numerous geometry modification methods proposed in the literature. One such method, historically prevalent in turbines, is the cavity squealer tip. However, its application in compressors, particularly of the centrifugal type, remains relatively underdeveloped. This study employs the Taguchi method's L-9 orthogonal array as a sensitivity analysis (utilizing Design of Experiments) to investigate the impact of cavity squealer design variables on the performance of the NASA-CC3 compressor at three key operational points: choke, design, and near stall regions. Computational fluid dynamics is utilized to derive performance parameters, and various sets of design variables result in improvements across pressure ratio, isentropic efficiency, mass flow rate, and surge margin. Notably, a significant 20 percent enhancement in surge margin is achieved in one instance. The performance at the remaining operating points varies among the nine cases, with improvements observed in some areas and declines in others. Processing the data yields three optimal geometries, with the best configuration enhancing all performance parameters (0.59% for design mass flow rate and 2.20% for efficiency, maintaining a constant pressure ratio compared to the base). As anticipated, the optimal impellers exhibit reduced flow leakage compared to the baseline.

Investigation on Aerodynamic Performance of a Centrifugal Compressor with Leaned and Bowed 3D Blades

The application of centrifugal compressors is extensive in industries such as aerospace and energy. The blade is the primary factor affecting the aerodynamic performance of compressors. In this paper, the aerodynamic performance of a centrifugal compressor with leaned and bowed 3D blades is investigated. The spanwise section profiles of the blade in the circumferential direction are deflected at different angles, resulting in four compressors with distinct leaned and bowed 3D blades based on the original model. There is a significant change in isentropic efficiency of the modified models under design conditions. Specifically, models 1, 3, and 4 experienced an increase of 0.97%, 1.04%, and 0.79%, respectively, while model 2 experienced a decrease of 0.70%. The profile of the blade tip and 50% spanwise section are shifted towards the suction surface, resulting in a geometric structure where the blade is concave towards the pressure surface. This structure gradually lifts the flow from the blade root to the blade tip downstream to the outlet area of the flow channel, reducing the load on the trailing edge of the blade and making the flow more closely aligned with the blade. At the same time, the larger radial velocity gradient near the blade tip suppresses the backflow on the shroud side, making the flow at the impeller outlet more stable. The outlet velocity of the impeller is more evenly distributed along the spanwise and circumferential directions, which improves the flow at the inlet of the diffuser and enhances the efficiency of the diffuser. Due to the high spanwise height of the leading edge of the blade, this bowed blade structure has little effect on the spanwise curvature upstream of the blade, resulting in negligible influence on the flow of the upstream channel.

Key Technologies and Application of Electric Scroll Compressors: A Review

The electric scroll compressor is driven by a built-in electric motor that rotates the scroll disk. It is known for its simple structure, adjustability, and high efficiency, making it highly promising for various applications. This paper reviews the current application and research status of electric scroll compressors. It covers topics such as the optimal design of scroll compressor profiles, scroll disk leakage sealing, and computer simulation optimization design methods. Additionally, the progress and development trends of vapor-injection scroll compressors (SCVIs) are discussed. This paper also presents the latest research progress on the application of the new refrigerant CO2 in electric scroll compressors, along with its latest applications that align with sustainable development requirements. Finally, this paper concludes with recommendations for the application of electric scroll compressors and suggests future directions for research.

Recent test experiences with applying multiple unshrouded impellers in a single-shaft compressor

The use of unshrouded impellers to increase the pressure ratio and volume reduction achieved in low mole weight, single-shaft compressor applications is discussed. The aerodynamic and mechanical implications of using multiple unshrouded impellers in series is also addressed. Test results will show that with proper management of impeller tip gaps good aerodynamic performance can be achieved with three unshrouded impellers in a single process section. The development effort also leveraged a knowledge-based impeller design system to provide new impeller designs that were optimized as a function of Mach number to provide a 30% axially shorter section without compromising aerodynamic performance. The shorter axial stages in the first section pushed the rotor natural frequency 20% higher, enabling faster rotor tip speeds. Test results from a single-stage test rig and from a full-size prototype testing are provided and generally show good agreement.

A Study of the Hydrodynamic Characteristics of Two-Dimensional Tandem Cascades

In comparison to single-row cascades, tandem cascades offer the advantages of reduced losses and enhanced operational capabilities, making them widely employed in compressor applications. However, current research on tandem cascades in hydraulic equipment remains relatively limited. In order to explore the potential application of two-dimensional tandem cascade structures in hydrodynamics and investigate their performance differences from single-row cascades, this study proposes a design scheme for a tandem cascade based on an existing single-row cascade design. Numerical simulation technology is utilized to compare and analyze the impact of these two designs on various flow losses under identical working conditions. The results indicate that compared to single-row vanes, the vane configuration of a serial-row design can better reduce losses and increase the pressure difference between the upper and lower surfaces of the vanes, thereby enhancing their load-bearing capacity and stability. This research finding is expected to provide valuable insights for future water pump design and optimization.

Performance and Analysis of PMBLDCM Drive using A Single-Stage PFC Half-Bridge Converter

Because of their excellent torque-to-weight ratio, small size, and great efficiency, Permanent Magnet Brushless DC Motors are widely used in a variety of applications. A buck half-bridge DC-DC converter acts as a single-stage PFC for a VSI-driven PMBLDCM powering an air conditioner's compressor. The PFC converter is fed from a single-phase AC main via a diode bridge rectifier. The VSI controls the PMBLDCM speed by adjusting the DC link voltage proportionally. The VSI functions solely as a commutator for the PMBLDCM, with stator current controlled by a rate limiter for speed changes. The PMBLDCM drive, incorporating a voltage-controlled PFC converter, is constructed, modeled, and simulated using the MATLAB-Simulink platform for an air conditioner compressor application. The system utilizes a 1.5 kW, 1500 rpm PMBLDC motor. Evaluation outcomes of the speed control strategy exhibit enhanced efficiency across a broad speed spectrum, showcasing the benefits of the drive system's integrated PFC functionality. Key Words: permanent magnet brushless DC motor, power factor correction converter, electrical drives.

Fast Method Of Image File Compression In Web-Based Application Form Using Huffman Algorithm

Many web-based applications/forms serve as online data entry devices equipped with facilities for uploading image data. When uploading image data, the image file is often incompatible or cannot be uploaded because the size is too large. Users have to resize those files separately. For example, with several compression applications used such as photoshop, gimp, photoscape, photo compressor, image size and many other compression applications. Web-based applications should be able to automatically resize the file according to the appropriate file size so that it can save time and speed up the process. To deal with the problem of automatic compression, the user must provide or build a web-based application that can directly compress files on the web because automatic file or image compression is available on the website without compressing them separately beforehand. With this automatic compression form application, it certainly reduces costs. (quota) internet, shortening time and also making it easier for users or users when uploading files on the web. The algorithm that is suitable for resizing files in online web applications is the hufman algorithm.

Thermo-mechanical properties and internal architecture of PI composites for high-pressure hydrogen applications

The efficient transport of Hydrogen is pivotal to the wide scale adaption of energy produced from renewable sources. Reciprocating piston compressors with high strength non-lubricated sealing solutions for piston and rod packing rings will be a key technology to fulfill gas purity and high-pressure gradients demands set by hydrogen applications. Polyimide polymer matrix composites have seen use in tribological applications and promise high mechanical strength and temperature resistance. The presented work describes carbon fiber reinforced Polyimide blends in comparison, characterized by complementary advanced methods to investigate their properties and potential for reciprocating compressor applications. Thermo-mechanical and tribological testing was supported by microstructure analysis utilizing synchrotron tomography and electron microscopy, pinpointing the necessity of dry lubricating additives such as PTFE. New insights in micromechanical deformation behavior of fiber reinforced polymers are given and promising fiber-reinforced polyimide compositions suitable for high-pressure hydrogen compression applications were identified.

Innovative design and experimental validation of dynamic balance in rotary compressors based on particle damping energy dissipation technology

Dynamic imbalance is one of the primary issues in rotary compressor applications, which can generate significant vibration. A dynamic balance design is required to minimize the moment and additional inertia force, which can be eliminated by adding a counterweight. This paper utilized a solid plate that has cavities filled with particle damper as a novel design to satisfy the dynamic balance. Vibrational energy is dissipated in collisions between particles through momentum exchange and is converted into energy for consumption that consists of inelastic collision energy and frictional energy. The discrete element method (DEM) and multi-body dynamics (MBD) were applied for two-way coupling for a dynamic balance simulation. The impact of particle size, friction coefficient, and restitution coefficient on energy dissipation in rotary compressors was evaluated, and the particle radius of 1 mm produced the most satisfactory. The experiment measured the vibrational acceleration in the tangential and radial directions at a particular duration and frequency to reflect the particle damper’s dynamic balance and energy dissipation effect. Both simulation and experimental results confirmed that the novel design features are more acceptable than the original to satisfy the dynamic balance of a rotary compressor.

Analysis of a Segmented Axial Active Magnetic Bearing for Multi-MW Compressor Applications

In high-speed compressor and turbine applications, active magnetic bearings are employed to increase reliability, reduce maintenance, and provide contact-free and oil-free operation. Evidently, the dynamic performance of active magnetic bearings must correspond to application-specific events like compressor surge or thrust disturbances. This article presents a segmented stator as one of the solutions to increase the bandwidth of axial active magnetic bearings (AMBs) and further improve the stability of the shaft system. We analyze the effects and discuss the tradeoffs of axial active magnetic bearing stator segmentation and slitting to alleviate bandwidth limitations. Finite element method design optimization and control plant modeling methods, open- and closed-loop tests, and identification of the overall thrust AMB–rotor control plant are studied.

An Evaluation of the Tribological Characteristics of Diaphragm Plates for High-Pressure Hydrogen Gas Compressor Applications

Diaphragm plates, a key part of high-pressure hydrogen gas compressors, are easily cracked or broken due to repeated shape deformations caused by pressure, resulting in increasing difficulties in maintenance. This study aimed to improve the durability of diaphragm plates. This investigation focuses on the potential for friction and wear reduction through the application of surface polishing and Teflon coating on two diaphragm plate materials, namely stainless steel 301 and Inconel 718. To achieve this, various metal substrates with diverse surface morphologies were prepared and subjected to comprehensive assessments of their surface, mechanical, and tribological properties. Research findings revealed that the surface hardness and tensile strength of stainless steel 301 surpassed those of Inconel 718. Through friction and wear analysis, it was observed that Teflon-coated diaphragm plate material with a microstructure demonstrated superior friction performance. Furthermore, finite element analysis was employed to investigate the stress behavior of stainless steel 301 under different applied loads and conditions, offering valuable insights into the diaphragm’s performance. From the results of this study, the excellence of the Teflon coating applied to the surface of stainless steel 301—the material of the hydrogen compressor diaphragm plate—was confirmed.

Electromagnetic Performance Investigation of Rectangular-Structured Linear Actuator with End Ferromagnetic Poles

Saving energy from domestic appliances is a focus in the effort to combat energy challenges. Linear compressors are a more efficient alternative to the traditional compressors used in refrigerators, which account for 20–40% of all residential electricity use. This article investigates the new topology of the moving magnet (MM), dual-stator single-mover linear oscillating actuator (DSSM-LOA) for linear compressor application. Both the stators were C-shaped, with coils looped across their end sides. Two permanent magnets (PMs) that were axially magnetized were housed on the mover. The PM structural shape significantly affected its fabrication cost and magnitude of magnetic flux density (B). The DSSM-LOA makes use of axially magnetized rectangular-shaped PMs because they are inexpensive and generate high electromagnetic (EM) force density. End ferromagnetic core materials were used to improve the magnetic flux, linking from the stator to the mover. All the design parameters were optimized through parametric analysis using the finite parametric sweep method. Parameters present within the three primary parameters (length, height, and depth) that were assumed constants were optimized, and the optimal dimensions were selected based on the EM force. The investigated DSSM-LOA was contrasted with traditional LOA designs, and they showed significant improvement in EM force per ampere, generally named motor constant (MC), MC per PM mass, MC density, cogging force, and stroke. Additionally, the proposed DSSM-LOA had a simple structure and low cost, and it operated in a feasible range of strokes for linear compressor application.

Hydrogenation behavior of a C14 Laves phase under ultra-high hydrogen pressure

For high pressure metal hydride (MH) compressor applications, it is important to have a thorough understanding of the hydrogenation properties of MH forming compounds under high pressure and temperature conditions, which are still little studied. Here, a Ti0.90V0.30Mn1.00Ni0.80 compound with MgZn2-type AB2 structure has been investigated by Sieverts’ method over a wide pressure and temperature range (up to 100 MPa and between −80 and 120 °C). This provided clear experimental evidence of the downward curvature of the van’t Hoff plot in the high-pressure region, which arises from the non-ideal behavior of hydrogen. In this paper, we also show that the high-sorption pressures can be well estimated by the van’t Hoff equation using low-pressure data. Ultimately, this study was combined with synchrotron radiation X-ray diffraction (SR-XRD) performed in an effort to monitor the structural evolution of the compound in situ under ultra-high hydrogen pressure. We found that even under extreme conditions of 2 GPa and 200 °C, both the main AB2 phase and the secondary CsCl-type AB phase were fully hydrogenated and their structures were conserved. The existence of a critical temperature for the AB2-H2 system was demonstrated from the evolution of the SR-XRD patterns recorded for several temperatures during the desorption process.

Design of imprecise compressor applications based on Hazy-Multipliers

Approximate multipliers are a trending digital design that was specially developed for the implementation of low power and high-speed circuits. The main purpose of this design is to trade the necessity of accurate multipliers. In this work, a novel imprecise compressor was designed to develop the Hazy Multipliers for low-error resilient applications. These imprecise compressors are synthesized using a 40 nm CMOS technology. When compared with the previous approximate multiplier design the proposed Hazy Multipliers are can reduce the error up to 96%, 98.9%, 99.5% respectively than the existing methods. Finally, the proposed design is investigated on the image smoothening application to show the performance metrics of Hazy Multipliers.

Advanced Method of Variable Refrigerant Flow (VRF) Systems Designing to Forecast Onsite Operation—Part 2: Phenomenological Simulation to Recoup Refrigeration Energy

This paper focuses on the application of speed-regulated compressors (SRCs) to cover changeable heat loads with high efficiency in conventional air conditioning systems (ACS) as well as in the more advanced variable refrigerant flow (VRF)-type outdoor and indoor ACS. In reality, an SRC is an oversized compressor, although it can operate efficiently at part loads. The higher the level of regulated loads (LRL) of the SRC, the more the compressor is oversized. It is preferable to reduce the size of the SRC by covering the peak loads and recouping the excessive refrigeration energy reserved at decreased actual loads within the range of regulated loads. Therefore, the range of changeable loads is chosen as the object to be narrowed by using the reserved refrigeration capacity. Thus, the general fundamental approach of dividing the overall heat load range of the ACS into the ranges with changeable and unchangeable loads, as previously developed by the authors, is applied for the range of primary changeable loads. Due to this innovative step, the principle of two-stage outdoor air conditioning according to changeable and unchangeable loads, also proposed by the authors, has been extended over the range of primary changeable loads to reduce the level of refrigeration capacity regulation and SRC size. To realize this, part of the changeable load range is offset by the reserved refrigeration capacity, leading to a reduction in the changeable load range and the SRC size by approximately 20% for temperate climatic conditions.

An Imbalanced Data Augmentation and Assessment Method for Industrial Process Fault Classification With Application in Air Compressors

An Imbalanced Data Augmentation and Assessment Method for Industrial Process Fault Classification With Application in Air Compressors

Harmonic Resonance Analysis of Shale Gas Distribution Network with Phased Load

Based on the background of achieving carbon peaking and carbon neutrality, the development and application of new high-power compressors, electric grid drilling RIGS and electric fracturing pump system provide new equipment support for the electric, green and intelligent development of shale gas fields in China. However, the harmonic pollution of shale gas grid becomes more serious due to the converter and frequency conversion device in the system, which easily causes harmonic resonance problem. Therefore, the harmonic resonance of shale gas grid is comprehensively analyzed and treated. Firstly, the working mechanism of compressor, electric drilling RIGS of the harmonic impedance model of electric fracturing pump system is established. Secondly, the main research methods of harmonic resonance analysis are introduced, and the basic principle of modal analysis is explained. Modal analysis method was used to analyze. Finally, harmonic resonance is suppressed. The results show that there may be multiple resonant frequency points in the distribution network changes, but these changes are relatively clear; if the original resonant frequency point of the resonant loop does not exist, the resonant frequency point disappears. The optimal configuration strategy of passive filter can effectively suppress harmonic resonance of distribution network in shale gas field.