Scroll Compressor Research Articles

Theoretical analysis and experimental validation of optimal vapor injection conditions for a low-pressure ratio scroll compressor

Theoretical analysis and experimental validation of optimal vapor injection conditions for a low-pressure ratio scroll compressor

Study on performance of scroll compressor for micro-refrigeration systems by CFD method

Study on performance of scroll compressor for micro-refrigeration systems by CFD method

Modeling and analysis of a novel CPSC/CI combined profile for scroll compressors

The scroll profile design has become a research hotspot and plays a decisive role in scroll machines. However, the modeling process is complicated due to different expressions of peripheral and central profiles in most full meshing profile (FMPs). Moreover, systematic modeling and in-depth property investigation of scroll profile are still insufficient. Herein, this study simplifies scroll profile modeling by constructing a novel FMP that combines a cubic power series curve (CPSC) with a circular involute (CI) to improve the properties of scroll compressors. An analytical model of CPSC/CI scroll wraps is proposed using the orthogonal components approach and validated by numerical examples. Geometric models to calculate chamber volume and gas load action length, and gas load models, are established. The effects of the CPSC/CI on the scroll wrap tip, built-in volume ratio and gas load are investigated. The proposed CPSC/CI enhances scroll compressor's properties by providing favorable properties not only with wider range of variation in scroll wrap tip and built-in volume ratio but also smaller gas load vibrations due to its superior flexibility, compared to circular arc/CI. This study provides new possibilities for enhancing scroll compressor performance through the design of scroll wrap profile.

Experimental and numerical study on scroll compressor under different profile correction and discharge ports shapes

The scroll compressor is an essential component in air conditioning and heat pump systems. This study examined an electric scroll compressor using R22 refrigerant, focusing on how modifications in the scroll head profile and discharge structure affect its performance. Initially, a semi-empirical model based on mathematical formulas was developed to predict the performance improvements of the updated scroll compressor. Three-dimensional simulation software was then used to illustrate changes in the internal flow dynamics before and after enhancements. The predictions were validated through experimental testing. Both the semi-empirical model and the three-dimensional unsteady numerical calculation model analyzed the effects of modifications to the tooth head profile and discharge port shape on compressor performance. The adoption of a PMP profile correction delayed the compressor discharge process, shifting the starting discharge angle from 315°to 344°, thereby reducing under-compression occurrences during operation and increasing volumetric efficiency by 1.31%. Additionally, mathematical formulas correlating temperature with compressor performance were developed from fitting data, predicting compressor behavior under various conditions. Moreover, replacing a circular discharge port with a waist-shaped port reduced power consumption by 0.59 kW, resulting in a more uniform temperature distribution and enhanced mass flow rate during compressor operation.

Research on faults diagnosis of dynamic balance in scroll compressor based on CWT-MViTV2

Abstract The dynamic balancing of rotor systems is a critical factor affecting the vibration of scroll compressors. Traditionally, the detection and correction of rotor dynamic balancing systems have relied on time-domain and frequency-domain analysis of vibration signals, as well as validation using rotor dynamic balancing test platforms. This paper proposes a novel fault diagnosis method for the dynamic balancing of scroll compressor rotor systems. This method acquires the time-domain vibration signals of the scroll compressor through online detection experiments. These signals are then transformed into time-frequency maps using continuous wavelet transform(CWT). By integrating the MViTV2 neural network, this approach enables effective identification of dynamic balancing fault types without requiring disassembly or shutdown of the machine. The fault types, corresponding to the offset of the balancing weight’s centroid, will provide direct data support for subsequent validation work. This study compares various neural network models combined with time-frequency maps and demonstrates that the proposed model achieves the highest accuracy of 99.749% compared to other models, and the method's generalizability is validated in the public dataset. Furthermore, the proposed model maintains a high accuracy of 94.872% in high-noise environments. After improvement, the accuracy of the model has been increased to 95.641%, the training time and the diagnosis time has been reduced to 0.240 iter/s and 0.0277s.

Numerical investigation on scroll compressor with intermediate discharge valve for VRF annual performance promotion

Over-compression of scroll compressor in variable refrigerant flow (VRF) system is a common problem in improving system efficiency because it operates in part load conditions for most of the year. By introducing intermediate discharge valves (IDVs) to allow gas bypass from compression chamber to discharge side during compression process, the over-compression loss can be eliminated. In this study, the characteristics of compression process in IDV compressor are analysed and the effects of IDV port location and port size on compressor efficiency are discussed based on the validated high fidelity scroll compressor model. It is found that the IDVs could be able to adjust gas bypass process in different compression ratio conditions and maintain high efficiency over wider compression ratio range than that of non-IDV compressor. In addition, the VRF system model is integrated to verify the system performance improvement by IDV compressor. It is found that VRF system performance is significantly improved in cooling conditions with the IEER enhanced by 23.9 %, while limited improvement is obtained in heating conditions as the operating compression ratios are relatively higher.

Characteristic analysis and diagnosis method optimization of scroll compressor pressure pulsation signal under voltage fluctuation

Under off-design conditions, scroll compressors can lead to reduced efficiency, motor damage, and even cause safety problems such as leaks or explosions. To solve the above problems, this paper analyzes the influence mechanism of different voltages on the spectrum of pressure pulsation signal and modulation signal and provides theoretical support for fault diagnosis and enhances the interpretability of the model. A voltage fault diagnosis method of scroll compressor based on Time-frequency Principal component Convolutional Network (TPCN) model is proposed. By demodulation analysis of the pressure pulsation signal of the low-pressure inlet and high-pressure outlet of the refrigerant in the scroll compressor, the spectrum information of the principal component modulation signal under different voltages is obtained. The pooling strategy is used to accurately identify and extract the fault information in the modulated signal spectrum as the input data of the model. The input data is divided into the training set and the test set according to the ratio of 8:2 to complete the training and testing of the fault diagnosis model. The experimental results show that the accuracy of TPCN model for the diagnosis of 5 types of faults reaches 100 %. The average accuracy of the model is 100 %, which indicates that the model has good stability.

Dynamic model and characteristic analysis of a combined algebraic spiral scroll compressor

The combined algebraic spiral (CAS) effectively maximizes the geometric performance of a scroll compressor; however, its dynamic behavior remains inadequately explored. Utilizing the geometric model of the CAS scroll compressor, this study derived the functional relationship between the meshing point and the rotation angle, and calculated the working chamber volume using the discrete Green's theorem method. A dynamic model of the CAS scroll compressor was developed, and the influence of various parameters on its dynamic characteristics was analyzed. The findings indicate that when the polar angle interval is less than 0.01π, the discrete Green's theorem method accurately computes the working chamber volume. Among the gas forces acting on the CAS scroll compressor, the axial gas force is the most significant, followed by the tangential gas force, while the radial gas force is considerably smaller. The tangential gas force predominantly influences the overturning and rotational moments. Notably, when the polar angles of the connection points between the higher-order curve and the starting and ending algebraic spirals are set at 1.5π and 3π, the gas force remains low while maintaining geometric performance. This configuration results in reduced variation in gas force and enhanced dynamic performance. The spiral coefficient and spiral index of the starting algebraic spiral should be set as intermediate values to ensure optimal geometric and dynamic performance of the CAS scroll compressor.

A Digital Image Method for Calculating the Working Chamber Volume of a Combined Profile Scroll Compressor

Background: The efficient and accurate calculation of working chamber volume can greatly contribute to the optimized design efficiency of the combined profile scroll compressor, but current papers and patents lack research on the method of calculating the working chamber volume of a combined profile scroll compressor. Objective: A method of using digital image processing is proposed to efficiently calculate the working chamber volume of a combined scroll compressor. Methods: This method discretizes and reconstructs the scroll profile that forms the working chamber into a coordinate sequence with equal involute angle intervals. By calculating the relationship between the coordinate sequence and the rotation angle, a general coordinate sequence that forms the working chamber profile is obtained. The real-time changes in the projection image of the working chamber during all the suction, compression and discharge processes can be accurately depicted. The digital image is processed to obtain the actual projection area of the working chamber, and thus, the volume of the working chamber is accurately calculated. Results: The digital image method can accurately calculate the volume change of the working chamber of the combined profile scroll compressor by selecting the appropriate involute angle interval and digital image size, with a mean relative error of less than 1%. At the beginning of suction and the end of discharge, the calculated volume has been found to have poor accuracy, with a maximum relative error higher than 10%. Conclusion: The digital image method has been found to have high accuracy, greatly reduce the difficulty of the analysis of the working chamber volume, and promote the design optimization of the combined profile scroll compressor, thus broadening the idea for the calculation method of the working chamber volume of the scroll compressor.

SSG-Net: A Multi-Branch Fault Diagnosis Method for Scroll Compressors Using Swin Transformer Sliding Window, Shallow ResNet, and Global Attention Mechanism (GAM).

The reliable operation of scroll compressors is crucial for the efficiency of rotating machinery and refrigeration systems. To address the need for efficient and accurate fault diagnosis in scroll compressor technology under varying operating states, diverse failure modes, and different operating conditions, a multi-branch convolutional neural network fault diagnosis method (SSG-Net) has been developed. This method is based on the Swin Transformer, the Global Attention Mechanism (GAM), and the ResNet architecture. Initially, the one-dimensional time-series signal is converted into a two-dimensional image using the Short-Time Fourier Transform, thereby enriching the feature set for deep learning analysis. Subsequently, the method integrates the window attention mechanism of the Swin Transformer, the 2D convolution of GAM attention, and the shallow ResNet's two-dimensional convolution feature extraction branch network. This integration further optimizes the feature extraction process, enhancing the accuracy of fault feature recognition and sensitivity to data variability. Consequently, by combining the global and local features extracted from these three branch networks, the model significantly improves feature representation capability and robustness. Finally, experimental results on scroll compressor datasets and the CWRU dataset demonstrate diagnostic accuracies of 97.44% and 99.78%, respectively. These results surpass existing comparative models and confirm the model's superior recognition precision and rapid convergence capabilities in complex fault environments.

Refined one-dimensional modeling and experimental validation of scroll compressor with vapor injection for electric vehicles

Vapor injection technology represents a highly promising avenue for enhancing the efficiency of heat pump systems within electric vehicles, especially in challenging cold ambient conditions. Although a simplified isentropic process is commonly employed to assess the thermodynamic functioning of scroll compressors with vapor injection (SCVI), it diverges significantly from actual operational dynamics. This study introduces a sophisticated 1D mathematical model that incorporates key factors such as internal leakage and thermal losses, thereby providing a more accurate representation of SCVI's operational realities. The research includes comprehensive performance evaluations of a short wrap profile SCVI, with a specific focus on low-temperature ambient conditions, supported by rigorous experimental validation. Comparative analyses against non-injection scenarios reveal notable enhancements, including a maximum 17.2 % increase in mass flow, a 10.5 % rise in heating capacity, and a 2.15 % improvement in heating COP. Both the simplified isentropic process calculation model and the enhanced 1D mathematical model are utilized to analyze compressor operations. The integration of internal leakage and heat loss considerations significantly narrows the gap between calculated and experimental results for heating capacity and discharge temperature, reducing discrepancies from nearly 20 % to a mere 4 %. This refined mathematical model demonstrates a high level of alignment with experimental data, achieving an accuracy within 5 % when assessing the compressor's real-world operational dynamics.

Unsteady flow and thermal dynamic performance of pre-compression characteristics in variable-speed scroll compressors

In the suction process of scroll compressors, a special thermodynamic phenomenon occurs, known as pre-compression, which significantly affects the inhalation capacity, volumetric efficiency, and thermal characteristics of scroll compressors. To explore its generation and impact, unsteady flow field distributions of the pre-compression phenomenon were obtained by numerical simulations. The pressure variation of the pre-compression phenomenon in air was analyzed, and the power consumption caused by pre-compression during the working process was investigated. Study results indicated that the pre-compression phenomenon is mainly produced by the geometric structure and operating features of the scroll compressor. The initial angle of the pre-compression phenomenon decreases by 31° as the rotational speed ranges from 3000 to 7000 r/min. The generation of the pre-compression phenomenon induces eddies in the suction chamber. Additionally, it was demonstrated that during the suction process, mass flow rate increases owing to the pre-compression phenomenon. The study is helpful for analyzing the suction process and improving operating efficiency of scroll compressors.

Mechanical simulation analysis of an electric scroll compressor

Abstract As a precision automotive component, electric scroll compressors have high requirements for reliability. In order to save the cost of environmental testing and shorten the market cycle of new products, the modal parameters of a compressor are measured, and the first six modal parameters are obtained. Secondly, the simplified finite element model of the compressor is established, modal analysis is carried out, and the modal frequency error obtained by the two methods is controlled within a reasonable range to ensure the accuracy of the modeling. Finally, based on the established simulation model, the structural response and stress of the compressor under various working conditions, such as sinusoidal vibration and random vibration, are analyzed, and the extreme values of displacement and stress are obtained. The results show that the structural design of the compressor meets the requirements of the environmental test of on-board equipment. The test and simulation methods used in this paper also have certain reference significance for other mechanical equipment.

Analysis of the oil temperature in a scroll compressor with oil carter at discharge pressure using propane as refrigerant: Performance analysis for abnormally low oil volume

Scroll compressors are widely utilized in refrigeration systems and heat pumps, operating through the interaction of two spiral-shaped elements, one stationary and the other orbital. These elements fit together and continuously oscillate, compressing the fluid into diminishing volumes. They offer significant advantages such as high volumetric and compressor efficiencies, low vibrations, and reduced leaks. In direct suction scroll compressors, the oil sump is at discharge pressure, resulting in a wide pressure difference between the housing and the backpressure chamber; also, the oil temperature is higher than in the most common suction-side oil crankcase design. Knowing the oil temperature is crucial in determining the properties of the oil/refrigerant mixture that affect the system's performance. It also allows us to estimate the amount of refrigerant dissolved in the oil. In the current study, a series of tests are conducted under various operating conditions to measure the oil sump temperature in a direct suction scroll compressor. This experimental campaign was conducted using a compressor with an unusually low oil level, and an analysis of the system's performance was performed until a failure occurred.

ANALYSIS OF SUITABLE METHODOLOGIES FOR COMPRESSOR MASS FLOW RATE CORRECTION TO OTHER SUPERHEAT LEVELS AND REFRIGERANTS

This paper investigates the impact of suction conditions and refrigerant on scroll compressor mass flow rate by using calorimeter tests from AHRI-11 and AHRI-21 reports, published by AHRI's Low-GWP Alternative Refrigerants Evaluation program. Two Copeland scroll compressors (20 and 51 cm3) have been analyzed including different suction conditions (SH = 11K, SH = 22K, Ti = 18ºC) and several refrigerants (R134a, R32, R410A, R404A, etc.). Previous studies have explored response surfaces for energy consumption and mass flow rate variables. This study aims to expand the analysis by identifying the optimal approach to extrapolate mass flow rate from specific suction conditions to others SH or suction temperature levels and refrigerants. The current compressor characterization standard relies on the 1981 Dabiri correlation to correct compressor mass flow rate with suction conditions. Thus, this study aims to assess the adequacy of this correction and explore alternative correction methods for improved results.

IMPACT OF THE MIGRATION FROM R410A TO R454C IN THE COMPRESSOR PERFORMANCE

The quasi-azeotropic mixture of refrigerants R410A replaced R-22 as the preferred refrigerant for use in residential and commercial air conditioners. However, newer regulations have mandated the phase-down of refrigerants with a high GWP as R410A, and thus, new substituting refrigerants and mixtures must be selected. Among the different possibilities, some manufacturers have been interested in mixtures such as R454C, composed of R32 and R1234yf (21.5/78.5), which has a GWP lower than the limit imposed by the new F-Gas regulation.In this study a variable-speed scroll compressor was tested working with both R410A and R454C at different operating conditions. From these tests, the compressor behavior with these refrigerant mixtures has systematically been analyzed in terms of compressor efficiency, volumetric efficiency, and working range.

Numerical analysis of scroll compressor performance with pre-discharge valve for low-temperature heat pumps

Scroll compressors are a crucial component of automotive air conditioning systems. When operating at off-designed working conditions, over-compression can occur in the scroll compressor. A pre-discharge valve (PDV) is proposed to enhance the performance of the scroll compressor under off-design working conditions. The performance of the scroll compressor with a PDV for a low-temperature heat pump system is simulated. The results show that the scroll compressor with the PDV structure has lower pressure in the compression chambers and improved over-compression compared to conventional scroll compressors. The use of the PDV also leads to a reduction in the temperature of the refrigerant gas in the compression chambers and a decrease in the leakage between the compression chambers. As the evaporating temperature increases from −25 °C to −5 °C, the mass flow rate and volumetric efficiency increase, and the discharge temperature decreases. At an evaporating temperature of −5 °C, the discharge temperature at the center discharge port of the scroll compressor with the PDV is reduced by 2.4 °C compared to the conventional scroll compressor. The input power of the scroll compressor is reduced by 165.4 W–897.7 W. The volumetric efficiency and the isentropic efficiency are improved by 0.13 % and 6.63 % respectively.

Dynamic Balance Simulation and Optimization of Electric Vehicle Scroll Compressor Rotor System

In order to solve the problem of imbalance of internal forces in the system caused by the gravity force of the eccentric wheel and the orbiting scroll close to the drive bearing and the rotational inertia force during the operation of the electric scroll compressor, a dynamic model of the rotor system of the scroll compressor that takes into account the effect of the gas force was established using the multibody dynamics software ADAMS/View 2020. Dynamic simulation analysis of the rotor system is carried out, focusing on the force of the drive bearing; a parametric optimization method is adopted to optimize the position of the center-of-mass coordinates of the eccentric wheel of the relevant components, and the relevant parameters are derived after optimization. The results show that by adjusting the center-of-mass position of the eccentric wheel it is possible to optimize the unbalance force and unbalance moment of the main shaft drive system; compared with the pre-optimization, the force fluctuation ranges of the drive bearing in the horizontal and vertical directions are reduced, the peak value is reduced by 18%, and the impact force of the drive bearing during the initial period of compressor operation is effectively relieved. Through optimization calculation, the vibration and noise of the system are reduced, the operating stability of the scroll compressor is improved, and analytical methods and theoretical guidance are provided for the design and prediction of the dynamic behavior of the scroll compressors.

Design passive magnetic mechanisms with modular magnet configuration for axial gas force balance in miniature scroll compressors

Miniature scroll compressors (MSCs) are recognized for their superior characteristics—compact design, silent operation and energy-saving performance. One of its main challenges is to maintain dynamic sealing between the fixed and orbiting scrolls during the operation. This paper adopts a passive magnet mechanism (PMM) to balance the axial gas force in MSCs. The PMM with an integral magnet configuration (IMC) is investigated first, and the dimensions of the magnet and fixed ring are found as the paramount factors to determine the magnitude of axial magnetic force. However, the IMC is unable to follow the unsteady characteristics of the target axial gas force, so the scrolls will experience a large period of over-sealing during its operation.To overcome this limitation, an innovative modular magnet configuration (MMC) is proposed and investigated. The height of each magnet segment is treated as individual design variable, and genetic algorithm optimization is carried out to seek for the best force balance performance according to two indices—maximum force difference (MFD) and integral-average force difference (IAFD). With precise design of each magnet segment, the MMC is able to provide unsteady magnetic force and thus better balance performance. Compared with the IMC, the improvements are up to 52 % reduction of MFD and 66 % reduction of IAFD. The derived superior MMC designs reveal a common characteristic that the “N” and “E” magnets have short segments at their outer fringe and the “S” and “W” magnets have short segments at their inner fringe. The axial magnetic force characteristics of the IMC and MMC are validated by prototype experiments.

Noise Analysis and Structural Optimization of Automobile Scroll Compressor Air Valve

The air conditioning compressor is a critical component in automobile heating, ventilation and air conditioning systems. However, compressor noise has long been a problem for automobile manufacturers. In recent years, the development and application of automobile air conditioning scroll compressors has increased significantly due to their low mechanical vibration and noise. However, their limitations in terms of airflow pulse and noise cannot be ignored, especially in low speed and high load conditions where the noise generated has a negative impact on driving and passenger experience. Noise and airflow pulses are important considerations that cannot be ignored. This study innovatively modifies the end cap structure of the scroll compressor, using the principles of expansion muffler and insertion tube structure, with the aim of improving the acoustic quality of the scroll compressor. The results show that the novel valve construction can significantly reduce the sound pressure level of the scroll compressor noise to a maximum of 75.20 dBA. The results of this study provide a theoretical basis and practical technical applications for future research and development in the automobile industry.