Rotary Vane Compressor Research Articles

Performance analysis of a novel air source ammonia/water cascade heat pump for heating buildings in subarctic climate

Performance of available air-source heat pumps (ASHP) for buildings is extremely influenced by the outdoor air temperature (OAT). When OAT falls below –20 °C, especially in subarctic climate, most commercially available ASHPs lose their defined functionality. To address this issue, a novel cascade heat pump (CHP) is proposed that utilizes two natural (with zero global warming index) refrigerants: ammonia, aka R717, as the low stage (LS) refrigerant, and water, aka R718, as the high stage (HS) working fluid. The proposed system is equipped with two rotary vane compressors for LS and HS. To desuperheat the compressor discharge temperatures and increase the HS heating capacity, liquid refrigerant is injected into the chamber of both LS and HS compressors. The wet compression is thermodynamically modeled and validated against experimental data available in the literature. Optimum design parameters such as the maximum allowable temperatures during compression and the minimum vapor quality after injection are obtained where the COP is maximized. Total exergy destruction, number/location of injectors and the injected amounts are also investigated. The proposed CHP can deliver 6.35 kW heating load at 50 °C with a COP of 1.985 when OAT is –40 °C. From a broader perspective, the proposed CHP not only proves its efficacy in extremely cold subarctic climates but also emerges as a pivotal player in addressing the global warming issue. This is accomplished through a dual approach to decarbonization—firstly, by electrifying heating processes and secondly, by substituting phased-out refrigerants with environmentally friendly natural alternatives.

Power loss analysis in a new oil-free rotary vane compressor: Experimental investigation and mathematical modeling

This paper presents the design of an oil-free rotor vane stage with a new tribological scheme. The new scheme differs from existing ones in that the sealing vane contain protrusions that rest on rolling unloading bearings located in the end covers of the cylinder. Experimental results on friction power losses in the new and traditional stages are provided, demonstrating that the implementation of the new stage design allows for an average reduction in friction power losses by a factor of 10. A mathematical model for calculating friction power losses in the rotor vane type compressor stage, implementing the new tribological scheme, has been developed. The analysis based on the mathematical model confirms the possibility of achieving mechanical efficiency values higher than 0.9 in oil-free rotor vane stages with a pressure ratio of 3 and a rotor speed of 3000 rpm, through the use of the new tribological scheme. It has been found that there is a redistribution of the importance and values of the main design parameters recommended for the design of oil-free rotor vane stages with the new tribological scheme, which determine its structural configuration, compared to its traditional design.

Data-driven compressor performance maps and cost correlations for small-scale heat-pumping applications

The performance of vapour-compression heat pumps depends crucially upon compressor selection and design. In this work, a unified modelling framework is developed to enable technoeconomic comparisons of compressors intended for small-scale heating applications (<30 kWth). Published information on 120 commercially available compressors is analysed and used to develop performance maps that predict isentropic efficiency over a wide range of working conditions. Additionally, cost correlations are established to predict price as a function of nominal compressor inlet volumetric flowrate. When rotary-vane compressors are an available option (i.e., for inlet volumetric flowrates up to 5 ∙ 10−3 m3/s), they consistently achieve a high isentropic efficiency (∼70 %) for the investigated pressure ratios (1.5–9.5). Scroll compressors have an even higher isentropic efficiency (∼75 %) at pressure ratios below 5.5, but this drops to 50 % at higher pressure ratios, while the isentropic efficiency of reciprocating-piston compressors is best (∼75 %) at higher pressure ratios (5.5–7.5). Utilising an air-source heat pump model, the compressor types are compared for countries with different weather characteristics and electricity prices. Rotary-vane compressors are associated with the lowest levelised cost of heat, but the comparison largely depends on location and heating requirements.

Mathematical Modeling of Rotary Vane Compressors Taking into Account the Mutual Influence of Tribological and Operating Parameters

Mathematical Modeling of Rotary Vane Compressors Taking into Account the Mutual Influence of Tribological and Operating Parameters

О взаимосвязи цифровых технологических платформ крупных химических и нефтеперерабатывающих производств с техническим обликом парка компрессорного оборудования

Issues related to possible problems in the implementation of digitalization programs for large enterprises for the processing of natural hydrocarbon and mineral raw materials, due to the discrepancy between the technical level of the existing fleet of compressor equipment of these enterprises, both with the requirements of modern production and modern achievements in the field of compressor engineering, are considered. It is noted that the discrepancy between virtual and physical technological objects leads to an overestimation of the costs of creating and maintaining IT products, as well as to a decrease in their efficiency. The ways of improving the element base of compressor equipment are proposed. A theoretical analysis of the functioning of an alternative design of a rotary vane compressor with water supply to its flow part is performed. Its example shows that there are obvious prerequisites for replacing the fleet of existing reciprocating process compressors with more advanced designs, the production of which can be completely based on domestic technologies and localized in the Russian Federation in the interests of the core industries of the processing industry.

Prediction and experimental study of radiated noise of rotating vane compressor under compound effects of multiple sources excitations

Aiming at the problem that it is difficult to accurately predict the radiated noise of rotary vane compressor under multi-source excitation, in this paper, the rigid body dynamics model and the dynamics model of airflow pulse excitation of the suction-compression-exhaust process of the rotary vane compressor were established, and the mechanism of multi-body contact excitation and airflow pulsation excitation for rotating vane compressor is expounded. Meanwhile, a flexible multibody finite element mesh model including a rotor, blades, cylinder, end cover and shell was established, and mechanical excitation and airflow pulse excitation were taken as mechanical boundary conditions to calculate the vibration response characteristics of the rotary vane compressor. To estimate the radiated noise of the rotary vane compressor, a compressor acoustic boundary element model was established, and a noise test bench system was built in a semi-anechoic chamber to compare and analyze the calculated noise value. At constant speed and acceleration, the rear sound pressure value is larger, followed by the right part, which is close to the exhaust port, and the front sound pressure is obviously lower than other points. The maximum relative error of sound pressure levels at four field points is 4.8%, and the average relative error of all measured points is 2.4%. The measured values are in good agreement with the calculated values, which verifies the accuracy of the radiated noise prediction model of rotary vane compressor.

Performance investigation and design optimization of novel rotating-cylinder sliding vane rotary compressors

Novel rotating-cylinder sliding vane rotary compressors (RC-SVRCs) are promising machines in energy conversion systems due to extremely low friction. However, three-dimensional visual investigations on geometrical optimizations of RC-SVRCs are highly limited. Besides, most flow mechanisms and leakage flow affected by geometric structures have not been fully revealed yet. Therefore, the sliding vane number, gap heights at vane tips and length-to-diameter ratio are numerically studied in this work. The results show that more sliding vanes (4∼12) lead to more uniform flow and temperature fields, lower mass flow rates and outlet temperature, less leakage between rotor and rotating cylinder. The mass flow rate, leakage mL1 between rotor and cylinder and leakage mL2 at vane tip of 8-sliding-vane scheme are 2.944 × 10−2, 9.949 × 10−4 and 3.692 × 10−5 kg·s−1, respectively. Gap height at vane tips has vital effects on flow fields. As the gap increases (0.01∼0.05 mm), mass flow rate and isentropic efficiency are decreased by 12.68% and 18.26%, the outlet temperature, leakage mL1 and mL2 are increased by 91.5 K, 69.60% and 22 times, respectively. High-temperature areas and leakage flow increase with the increase of cylinder length, which is recommended no longer than 0.6 diameters. This work allows making recommendations for designing RC-SVRCs.

Geometric Optimisation of a Coupled Vane Compressor

The coupled vane compressor (CVC) is a rotary compressor with two coupled vanes which slide diametrically through the rotor during operation. As compared to most other rotary vane compressors, this CVC works well with small rotor-to-stator diameter ratio, typically less than that for all existing rotary compressors (>0.7). Hence, CVC has probably the most compact design among all rotary compressors, thus saving materials and manufacturing cost. This compressor is intended for use in room air-conditioners and refrigerators. Currently, mathematical model and measurement have been carried out to determine the working characteristics of this compressor. In this paper, a genetic algorithm with constraints handling has been devised and linked with the verified mathematical model of the CVC to search for a set of geometrical parameters which produces highest COP when working in the refrigeration cycle. During this optimisation search process, the significant design variables such as rotor radius, cylinder radius, vane thickness and valve reed thickness are allowed to vary.In this paper, the details on the application of the optimization process, constraints handling and descriptions, objective function definitions as well as the details of optimization implementation will be presented and discussed. Results obtained will be shown and deliberated. The results show that this optimization study reconfirms the value of optimisation in compressor design.

Analysis, modeling and simulations of an innovative sliding vane rotary compressor with a rotating cylinder

A novel sliding vane rotary compressor with a rotating cylinder is proposed in this paper. The sliding vane dynamics analysis reveals that, compared with the traditional compressor, the friction loss at the sliding vane tips and between rotor and cylinder can be reduced to 0.25% and 10.23%. To numerically investigate the internal flow mechanism, a reliable three-dimensional simulation method is developed via Fluent 2020R1. Three pressure ratios are considered. During transient calculations, all parameters begin to fluctuate periodically after the fourth round. Both temperature and pressure for a single chamber reach the maximum near the exhaust port. As the pressure ratio εp increases from 5, 10 to 15, the outlet temperature increases from 496.9, 623.0 to 754.4 K and the mass flow rate decreases from 0.03089, 0.02946 to 0.02764 kg/s, the volumetric efficiency and isentropic compression efficiency decrease, with the maximum values of 97.14% and 90.33%. The gaps between the rotor and the cylinder and at the vane tips are 0.03 and 0.01 mm, but the leakage mass of the former is one order higher than that of the latter. The research can provide guidance for the design and practical application of sliding vane rotary compressors.

Impact of discharge port configurations on the performance of sliding vane rotary compressors with a rotating cylinder

With the increasing requirements of compressed gas energy storage systems for compressors and expanders, sliding vane rotary compressors are worth trying. To study the influence of different configurations of discharge ports on the performance of compressors, numerical simulations are conducted on the innovative sliding vane compressors with a rotating cylinder. The reliable Renormalization Group k-ε turbulent model is adopted in Fluent 2020R1. The results show that as the coverage angle increases, the averaged mass flow rates increase, the averaged exhaust gas temperature decreases and the leakage between the rotor and rotating cylinder and at sliding vane tips decrease. When the coverage angle increases from 15° to 45° at the central position angle of −28°, the volumetric efficiency increases from 89.38% to 92.65% while the isentropic efficiency increases from 76.43% to 86.19%. When the central position angles range from −28°, −23° to −18° at the coverage angle of 30°, the farther the discharge port is to the narrowest gap between the rotor and cylinder, the lower the outlet temperature, the less the leakage flow, and the higher the isentropic efficiency. The scheme with the central angle of −28° and coverage angle of 45° is recommended as the best one.

Performance evaluation of a rotating sleeve vane compressor

This paper presents the performance study of a new designed rotating sleeve vane (RSV) compressor. The aim of this study was to develop a more compact semi-hermetic refrigerant compressor for refrigeration and air-conditioning systems, which will improve the conventional design in terms of sizing and operating mechanism. Experimental study was carried out on the prototype of a single and multi-vane (three and five-vane) RSV compressor prototypes with identical size of rotor and sleeve and tested the in a test bench of R134a refrigeration system. Each test was carried out in a steady state of refrigeration thermodynamic cycle at operating speed varied between 1000 rpm to 1500 rpm to obtain the mechanical and volumetric efficiencies. The experimental results on the three of the new prototypes were analyzed and found that that the single vane compressor prototype has a similar volumetric efficiency of about 90% with that of rolling piston compressor of equivalent capacity. A double increment in capacity to about 48 cc was observed in the five vane prototype models with the same overall dimension and configuration of the rotating components to that of the single vane. The volumetric efficiency was also comparable of about 70% to an existing multi vane rotary compressor.

Investigation of the influence of the number of vanes on the performance of a rotary vane compressor

We developed a mathematical model for determining the parameters of mass transfer in the compressor chambers during the processes of compression and discharge. The mass flow rates through the end and radial gaps were determined. Also we analyzed the processes of mass transfer in a clamped volume. We investigated the influence of the number of vanes on the compressor efficiency, taking into account changes in the compressor geometric parameters. We established that overflows through the end surfaces of rotor mainly affect the compressor performance. In order to reduce overflows during the period of discharge, it was proposed to increase the angle of closure of the discharge window at a fixed angle of its opening. The mathematical model allows one to make recommendations on the choice of the optimal number of vanes for a particular design.

Performance evaluation of a novel dual vane rotary compressor

Sliding-vane rotary compressors have considerable advantages in comparison with other positive displacement compressors in terms of volumetric efficiency, and continuity of flow without pulsations. However, sliding-vane rotary compressors have relatively low pressure ratio. This paper presents a novel design of a two-stage sliding-vane rotary compressor in attempt to elevate the pressure ratio of that type of compressors. The basic design features of the novel design are illustrated along with the adopted design geometry after studying the effects of several geometrical factors and their practicality. After several trials, the first prototype of the two-stage sliding-vane rotary compressor has been manufactured and tested experimentally to evaluate its performance. The paper reports the preliminary results of the flow rate, pressure rise and power consumption at different rotating speeds. Comparison of the performance of each stage is also included and the benefits of using the second stage are highlighted. The paper also summarizes the design challenges encountered during its manufacturing in addition to the challenges to reduce inter-stage leakage and the applied solutions.

Deforming grid generation for numerical simulations of fluid dynamics in sliding vane rotary machines

The limiting factor for the employment of advanced 3D CFD tools in the analysis and design of rotary vane machines is the unavailability of methods for generation of a computational grid suitable for fast and reliable numerical analysis. The paper addresses this issue through an analytical grid generation based on the user defined nodal displacement which discretizes the moving and deforming fluid domain of the sliding vane machine and ensures conservation of intrinsic quantities by maintaining the cell connectivity and structure. Mesh boundaries are defined as parametric curves generated using trigonometrical modelling of the axial cross section of the machine while the distribution of computational nodes is performed using algebraic algorithms with transfinite interpolation, post orthogonalisation and smoothing. Algebraic control functions are introduced for distribution of nodes on the rotor and casing boundaries in order to achieve good grid quality in terms of cell size and expansion. For testing of generated grids, single phase simulations of an industrial air rotary vane compressor are solved by use of commercial CFD solvers FLUENT and CFX. This paper presents implementation of the mesh motion algorithm, stability and robustness experienced with the solvers when working with highly deforming grids and the obtained flow results.

Structural optimal design of a swing vane compressor

In this paper, a novel swing vane rotary compressor (SVC) was introduced, which had significant advantages—simple mechanism, reduced frictional loss, reliable operation, and a comparatively higher compression ratio. Based on the swing vane compressor geometry model, thermodynamic model and kinetic model, the mathematical model of optimum design was established, and further theoretical and experimental studies were conducted. The length of the cylinder, radius of the rotor and cylinder were defined as design variables and the reciprocal of EER as objective function. The complex optimization method was adopted to study the structure of the swing vane compressor. The theoretical model could provide an effective method for predicting compressor performance, which would also contribute to structural optimization of the SVC. The study shows that the friction loss of the compressor are greatly reduced by optimized design in a given initial value, and the EER increased by 8.55%.

Motor Conversion for Reduced Energy Consumption: Compressor Applications Use More Energy Than Applications with Newer Technologies

Significant energy savings can be achieved by converting inefficient direct-driven rotary vane compressor applications to belt-driven applications.

Model based design of an intercooled dual stage sliding vane rotary compressor system

Energy saving is currently one of the most important driving factors for innovation all over the world. With reference to global electricity consumptions, electrical energy for compressed air production accounts for 4-5%. Among the rotary compressor technologies, Sliding Vane Rotary Compressors (SVRC) are characterized by noteworthy specific energy consumptions and demonstrated an unforeseen energy saving potential thanks to some intrinsic features specifically related to this kind of machines. The paper presents a further reduction strategy to lower energy consumptions in compressed air systems using SVRCs that relies on the combination of the recent use of a pressure swirled oil injection technology and a dual stage intercooling. The synergy between technologies already mature approaches to the lowest energy consumption and candidates SVRCs as superior machines in the energy context. The saving potential compared to the technology at the state of the art was evaluated thanks to a comprehensive mathematical modeling of the two compressor sections and the intercooling heat exchanger and fan. Results showed a reduction of the electrical power required to drive the compressor system up to 9.5%. The overall approach represents a model-based design for a new machine which is under development.

Profile design for the cylinder of a double-acting rotary vane compressor

Inner wall profile of the cylinder in a rotary vane compressor (RVC), which influences the motion characteristics of vanes, suction volume, friction characteristic, etc., plays an important role in the performance of the compressor. This work mainly aims at the profile design of a new cylinder for a double-acting RVC with harmonic profile cylinder on the basis of not changing integrate size. According to the relation between cylinder profile and vane motion characteristics, a method for the cylinder profile design is proposed in this paper. With an assumed vane motion, equations of the cylinder profile, cell volume of the compressor as well as pressure angles between vanes and cylinder inner wall are constructed preliminarily. And then through adjusting parameters and optimization with an independently developed procedure, a new cylinder with the so-called combined profile is obtained. Theoretical analysis of the cell volume variations and the pressure angles between vanes and cylinder are conducted. The results show that there is neither rigid impulse nor soft impulse between vanes and cylinder due to the vane continuous motion including displacement, velocity and acceleration. And the pressure angles between vane and cylinder and working volume of the compressor with the new profile cylinder are superior to harmonic profile cylinder, which is useful for the reduction of friction power in the operation of compressor. Experiments show that the cooling capacity and COP of the test refrigeration cycle with the proposed combined profile cylinder is higher than the compressor with harmonic profile cylinder. And the volumetric efficiency and isentropic efficiency of the compressor with combined profile cylinder have better performance. This method can be applied to the design of the cylinder for multiple-acting rotary vane compressors, rotary vane expanders and vane pumps.

Friction power modeling and measurements in sliding vane rotary compressors

In compressed air systems, mechanical and organic losses account for 15% of compressor energy consumption. In the current research, the energy saving potential achievable through friction power reduction in sliding vane rotary compressors was investigated using experimental and modeling approaches. Tests on a new mid-size industrial compressor operating at different steady conditions (outlet pressure 9, 12.5, 14.5 bar at 1000 and 1500 RPM) assessed the machine performance through measurement of mechanical power and the reconstruction of the pressure-volume diagram. An experimental methodology was also developed to quantify the power lost by friction and its measurement uncertainty using the concept of indicated mean effective pressure. Modeling the compressor blade dynamics allowed a friction power decomposition while an analysis of the hydrodynamic lubrication at the most severe friction location, namely between blade tip and stator wall, additionally provided the oil film thickness evolution along the contact surface. The agreement between modeling and experimental data identified a value for the friction coefficient of 0.065. Design suggestions on existing machines and new design solutions were eventually outlined varying blade mass, revolution speed and compressor aspect ratio. These improved configurations predicted an efficiency increase up to 6%.

Theoretical modeling and experimental investigations for the improvement of the mechanical efficiency in sliding vane rotary compressors

Positive displacement compressors lead the market of compressed air production for industrial applications. Among them, sliding vane rotary compressors represent an energetically virtuous alternative to the current compression technologies. In the present work, the effects of compressor design parameters were investigated through a comprehensive approach that aimed at addressing more efficient machines to promote sliding vane compressors as the key enabling technology in compressed air systems. A comprehensive mathematical model was developed to study the main phenomena occurring in this kind of compressors. The model provides the cell volume evolution over a whole rotation during which filling, compression and discharge processes occur. The first and latter phases are described by the quasi-propagatory approach that represents the inertial, capacitive and resistive features of one-dimensional unsteady flows. The dynamics of the compressor blades led to four different arrangements inside the rotor slots while an analysis of the hydrodynamic lubrication established between blade tip and stator wall focused on the oil film thickness evolution to prevent dry contacts. An extensive experimental campaign on a mid-size industrial compressor allowed the model validation at different outlet pressure levels and revolution speeds using a direct measurement of mechanical power and the reconstruction of the indicator diagram from piezoelectric pressure transducers. The friction coefficient at the contact points between blades with stator and rotor was estimated in 0.065 and further improvements of the mechanical efficiency were eventually addressed considering the roles of compressor aspect ratio, revolution speed, and blade tilt. The first two theoretical optimizations might lead to an increase of the compressor efficiency of 2 and 9 percentage points respectively. On the other hand, acting on the blade tilt would not produce relevant improvements.