Piston Compressor Research Articles

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.

Investigation on topology-optimized compressor piston by metal additive manufacturing technique: Analytical and numeric computational modeling using finite element analysis in ANSYS

Abstract Air compressors are widely used in factories to power automation systems and store energy. Several studies have been conducted on the performance of reciprocating and screw compressors. Advancements in design and manufacturing techniques, such as generative design and topology optimization, are leading to improved performance and turbomachinery growth. This work presents a methodology to design and manufacture air compressor pistons using topology optimization and metal additive manufacturing. The existing piston is converted to 3D CAD data and topology optimization is conducted to reduce material in stress concentration regions. Thermal and mechanical loads are considered in boundary conditions. The results show reduced material and improved efficiency, which is validated using ANSYS fluent. The optimized 3D model of the piston is too complex for conventional subtractive manufacturing, so laser sintering 3D printing is proposed. Honeycomb pattern infill patterns are used in 3D printing. This investigation is a step toward researching similar methods in other reciprocating compressor components such as cylinder, cylinder head, piston pins, crankshaft, and connecting rods, which will ultimately lead to improved compressor efficiency.

Performance investigation of a wave-driven compressed air energy storage system

The intermittent nature of waves causes a mismatch between the energy supply and demand. Hence an energy storage system is essential in the utilization of wave energy. This paper proposes a novel wave-driven compressed air energy storage (W-CAES) system that combines a heaving buoy wave energy converter with compressed air energy storage. Wave drives the heaving buoy to convert the wave energy to mechanical work that pumps water into a water-air compression chamber to form a liquid piston compressor. Air is compressed in the chamber and the wave energy is stored in the air. A numerical model was first developed in ANSYS-AQWA and validated using experimental data. Then this model was applied to evaluate the hydrodynamic characteristics, power generation capacity and thermodynamic behaviour of the W-CAES system under different wave conditions. Furthermore, the impacts of geometric parameters of the wave energy converter and compression chamber on the system performance were investigated. Results indicated that energy storage power was improved as the hydraulic cylinder area and storage pressure increased. The energy storage efficiency and round-trip efficiency could reach 60.5 % and 47.1 %, respectively under the isothermal compression process. By comparing the proposed W-CAES system with the conventional wave energy converter prototype under the same conditions, it showed that the proposed system yielded an increase in power output by up to 30 % under Tasmania wave conditions under an isothermal compression. The overall system wave capture factor is more sensitive to wave height than wave frequency. The capture factor can be as high as 20 % under Tasmania wave conditions. This study provides a new method for efficient wave energy conversion and storage.

ОБГРУНТУВАННЯ ВИБОРУ РЕГУЛЯТОРА ШВИДКОСТІ ЕЛЕКТРОПРИВОДА ОДНОЦИЛІНДРОВОГО ПОРШНЕВОГО КОМПРЕСОРА

The peculiarities of the operation of closed systems of speed regulation of electric drives of single-cylinder piston com-pressors due to the presence of a non-linear dependence between the load torque and the angular movement of its rotor are considered. It is shown that the presence of an internal nonlinear connection, which forms a load torque, in a closed control systems can lead to subharmonic mechanical self-oscillations, which worsen the power and performance indicators of the electric drive. The use of static controllers is proposed to eliminate subharmonic self-oscillations and increase the efficiency of the electric drive. Ref. 10, fig. 6. Keywords: piston compressor, self-oscillation, method of harmonic linearization, static controller.

Dynamic characteristics of refrigerant and lubricant in R290 rolling piston compressor of low-temperature air to water heat pump (LT-AWHP) during defrosting cycle

The dynamic characteristics of refrigerant and lubricant in R290 rolling piston compressor used in LT-AWHP (ambient temperature (ta) of 7 ∼ −30 °C) are not clear at present. In this study, the changing characteristics of suction and discharge pressure and temperature, physical properties of oil sump (temperature, viscosity, solubility) and oil sump liquid level in the high pressure shell double-cylinder rolling piston compressor during defrosting cycle (steady state→ defrosting→ steady state) were experimentally researched in a R290 LT-AWHP with the rated power consumption of 1.9 kW using PAG40 and POE68 lubricants at ta of −12 and −20 °C. The results show that, the defrosting time and the change rule of oil sump physical properties are different when completely miscible oil and partially miscible oil used, but the defrosting time (about 3 – 5 min) is less than that of the R290 air to air heat pump (about 8 min). After defrosting, the fluid in the upside of compressor shell remains liquid and gas mixture for a long time, which would decrease total heating performance of the heat pump. After defrosting, oil sump viscosity is lower than the steady state value for a long time after discharge pressure is stabilized again. Within a period after the four-way valve reversing, the oil sump liquid level drops a lot, which may result in metal wear for insufficient oil supply on the side of sliding vane. This research would promote the improvement of defrosting process and provide guidance for the lubricant selection of R290 LT-AWHP.

The Effect of the Isolator Size on the Efficiency of Rotary Piston Compressors

A hybrid renewable-hydrogen green energy system combines renewable energy sources with hydrogen production and storage technologies to create a sustainable and efficient energy system. One of the major components of such systems is compressors, which influence the system’s overall efficiency. Therefore, this research paper will study design modifications that improve the efficiency of these components. More precisely, this study examines the correlation between a concentric rotary piston compressor isolator size and efficiency. The objective is to determine the significance of size on the compressor’s performance. Two distinct mechanisms and operational designs employed in such compressors are investigated. Irrespective of the compressor design, it is revealed that the isolator’s diameter considerably impacts the pressure ratio of these rotary compressors. Specifically, the conclusion is that a larger isolator increases efficiency; a 35% larger RSP diameter results in a 145% increase in peak pressure for Mechanism 1. A 100% larger RSP diameter yields a 180% boost in peak pressure for Mechanism 2.

Research on precise control of piston eccentricity by electromagnetic levitation in labyrinth piston compressor

The piston in the Labyrinth piston compressor (LPC) usually runs eccentrically in the cylinder, which results in large internal leakage and low volumetric efficiency. An active electromagnetic control method based on the electromagnetic levitation theory was proposed in this paper to control the piston eccentricity, and a triple close-loop multi-factor coupled feedback control strategy composed of a current loop, a velocity loop, and a displacement loop was designed to realize the levitation control of the piston. The experimental research shows that there is serious piston eccentricity in the LPC, and the piston eccentricity is positively correlated with the increase of compressor pressure ratio and speed. By adopting the active electromagnetic control system proposed in this paper, the piston eccentricity is significantly reduced, and the maximum reduction is over 88%. Further research shows that the volume flow rate and volumetric efficiency of the LPC with control are maximum improved by about 45.6% and 44%, respectively. In conclusion, the piston eccentricity in the LPC could be effectively reduced by adopting the active electromagnetic control method proposed in this paper, thus improving its performance.

Compressor and Valve Control Performance Implications on Active Flow Control Aircraft

This study presents the feasibility of implementing commercial-off-the-shelf reciprocating piston compressors for a developed active flow control (AFC) actuation framework to quantify the aerospace relevant performance ramifications of control architecture and compressor operational choices. Three architectures are studied: supply valve metering, exit area metering, and a combined approach. All concepts are studied under varying compressor operation schedules. The analysis framework in this study integrates internal pneumatic actuation and discharge dynamics, an experimentally calibrated compressor pressure and thermal dynamics model, three feedback control architectures, and flight dynamics models. The framework is implemented in simulation to provide a user-friendly tool for linking AFC architecture choices to achievable flight trajectories. Actuator performance is evaluated using actuation time, output, compressor duty cycle, and specific energy consumption. Aircraft tracking performance is evaluated as usable time and slalom centerline deviation. The analysis indicates that a supply-volume-based metering approach is comparatively inefficient concerning an exit-area-based metering, resulting in high flight tracking error. Exit area metering provides the best efficiency and run time with some structural drawbacks, while the combined approach provides the best flight tracking performance at the expense of additional complexity. These results inform the choice of onboard AFC hardware choices.

Quantitative diagnosis of loose piston rod threads in reciprocating compressors for hydrogen storage and transport

Fracture of the piston rod yields catastrophic accidents in reciprocating hydrogen compressors, resulting in costly and time-consuming maintenance and developing the latest challenge to hydrogen safety and economy. The fracture-prone section is mostly located at the connecting thread of the crosshead or of the piston, mainly due to thread loosening and hereby insufficient preload followed by fatigue and fracture. Here, a novel quantitative diagnosis method for thread loosening of hydrogen reciprocating compressor piston rods was proposed. First, a finite element model of a single-throw reciprocating compressor was established to analyse the dynamic behaviour of the operating posture and load pattern at the crosshead and piston rod connecting thread. Further, the impact events triggered by crosshead displacement and rod load reversal events were identified to enhance the interpretability of the signal, thereby obtaining a loose-sensitive frequency band of 2–15 kHz and specific phase angle features. Next, the multi-band feature spectrum was formed using variational modal decomposition and data dimensionality reduction based on the Hilbert transform, which demonstrates satisfactory performance in the feature reservation as well as spectrum compression of acceleration signals in both the time and frequency domain. The proposed methodology was validated by experiments with various levels of thread loosening. The result indicated the multi-band feature spectrum feature was effective in quantitative loosening diagnosis with accurate and stable classification.

Theoretical and experimental investigation on the rolling piston compressor with enhance vapor injection for heat pump system

The rolling piston compressor with enhanced vapor injection (EVI) is widely used in the household air-source heat pump system. To study the thermodynamic performance and the optimal injection pressure, this paper presents a mathematical method to simulate the whole working process of rolling piston compressor with EVI, which considers suction backflow process, discharge process, vapor injection process and leakage process. According to the calculation, the effects of injection pressure on discharge mass flow rate, p-V diagram and indicated power have been analyzed. In order to verify the accuracy of simulation, an experiment has been carried out to obtain the discharge mass flow rate and the errors between simulated and experimental results are within 4%, which shows that the proposed method is precise enough. Additionally, the experimental results show that EVI can not only improve the heating capacity and COP but also decrease the discharge temperature. However, the optimal injection pressure corresponding to the maximum heating capacity is different from that corresponding to the maximum COP. From the perspective of the heating capacity, the optimal injection pressure is a little higher than the geometric mean of suction pressure and discharge pressure but from the perspective of COP, the optimal injection pressure is a little lower than the geometric mean.

Importance, influence and limits of CFD radiation modeling for containment atmosphere simulations

In the appearance of steam, the CFD modeling of thermal-hydraulic phenomena in reactor containments during various phases of an accident necessarily requires consideration of radiative heat transfer. These radiation phenomena involve (i) energy transfer within the gas mixture and (ii) between the gas and the surrounding structures which have a much higher thermal inertia. Preliminary calculations performed for the present experiments in the OECD/NEA HYMERES-2 project with the CFD code containmentFoam using a Monte Carlo thermal radiation solver with non-gray gas modeling of steam absorption, showed that radiant heat transfer is important even with a very low amount of steam (≈ 2%). Therefore, the test matrix was tailored to the two opposite extremes: Either gas compositions with low steam content, where radiative heat transfer can be neglected, or gas mixtures containing larger amounts of steam, so that radiative heat transfer plays a dominant role. For the two selected experiments within the H2P2 series and the corresponding CFD calculations, a vessel with a diameter of 4 m and a height of 8 m was preconditioned with different mixtures of air/steam at room and elevated temperatures. This was followed by the build-up of a stable helium stratification in the upper part of the vessel. Helium was then injected from the top at a higher mass flow rate, which (a) compresses the gas atmosphere, (b) resembles piston compression and (c) leads to a height-dependent and transient increase in gas temperature below this helium stratification, influenced by thermal radiation effects — or their absence. These experiments and the associated CFD calculations were developed to isolate the thermal radiation phenomena as much as possible from convective and diffusive effects. They are the first of their kind to be conducted in a large-scale thermal-hydraulic facility. It is demonstrated (a) that neglecting thermal radiation for the high steam content case, the temperature rise is significantly over-predicted by a factor of two compared to the application of the suggested Monte Carlo thermal radiation solver with non-gray gas modeling, (b) the computational effort considering CFD and non-gray gas radiation is feasible with the suggested tailored Monte Carlo solver and (c) that the suggested radiation model outperforms the widespread used P1 radiation model.

Theoretical and Experimental Comparison of Revolving Vane Compressors and Rolling Piston Compressors

Rotary compressors have some advantages such as lower noise, vibration, lower cost and few parts. For this reason, it is preferred more than its substitutes such as piston, screw and sliding compressors in cooling and air-conditioning systems. In this study, two different designs, rolling piston and revolving vane, were made to increase the performance of the double-stage, rotary compressor with a volume of 22.6 cc. When the test results are examined, it is seen that the rolling piston compressor consumes 1.3 times less power than the electric motor for 2700 rpm and 3 bar pressure, due to the lower inertia forces compared to the revolving vane compressor.

Control optimization of taper interference coupling system for large piston compressor in the smart industries

Abstract To study the control optimization of conical interference connection system for large piston compressor, the reliability optimization and reliability optimization design of conical interference connection were systematically described. By using the proposed method, the maximum operating reliability can be obtained under the condition of constant interference joint size, namely, reliability optimization. Alternatively, the desired working reliability can be designed into the mating connection by optimizing parameters (combining size and interference), namely, reliability optimization design. Design value of 2.12 compression ratio is significantly higher than the unit level. As a result, the mid-stage exhaust temperature of the unit is as high as 124°C, and it is in high temperature operation state. It has been proved that conical interference connection is widely used in hydraulic transmission device because of its advantages of simple structure, reliable operation, and ability to bear certain impact load, reliable transmission torque than general connection, and convenient assembly and disassembly and has been proved to be reliable in practice.

Influence of Rotational Speed on Isothermal Piston Compression System

An isothermal piston is a device that can achieve near-isothermal compression by enhancing the heat transfer area with a porous media. However, flow resistance between the porous media and the liquid is introduced, which cannot be neglected at a high operational speed. Thus, the influence of rotational speed on the isothermal piston compression system is analyzed in this study. A flow resistance mathematical model is established based on the face-centered cubic structure hypothesis. The energy conservation rate and efficiency of the isothermal piston are defined. The effect of rotational speed on resistance is discussed, and a comprehensive energy conservation performance assessment of the isothermal piston is analyzed. The results show that the increasing rate of the resistance work increases significantly proportional to the rotational speed, and the proportion of resistance work in the total work increases gradually and sharply. The total work including compression and resistance cannot be larger than the compression work under adiabatic conditions. The maximum rotational speed is 650 rpm.

Study on performance of a gas engine-driven heat pump system with R410A for heating and domestic hot water applications

Traditional gas engine-driven heat pump (GHP) systems were switched off in the transitional season, and the engine waste heat could no longer be used for producing domestic hot water. Most studies on GHP systems used piston compressors with low efficiency, and the refrigerants used were R134a or R407C. This paper presents an innovative GHP system using open scroll compressors with R410A which can be used throughout the year. The novel GHP system can be switched freely between heating mode-H, which produced heating water combined with domestic hot water, and heating mode-D which only produced domestic hot water. In these two heating modes, the effects of different condenser water outlet temperatures (tw,out1), domestic hot water outlet temperatures (tw,out2), engine speeds (Neng), and total domestic hot water outlet temperatures (tw,out3) on performance of the GHP system for heating and domestic hot water applications were experimentally investigated. The results show that tw,out1 and tw,out3 have greater effect on primary energy ratio (PER), Neng has significantly larger effect on heating capacity and the recovered waste heat, whereas tw,out2 has little effect on the comprehensive performance. The change between heating mode-H and heating mode-D hardly affects the system heating performance. For the experiments, the waste heat recovery rates are between 42.05 % and 61.08 %. The total PER of the GHP system ranges from 1.179 to 1.453 without waste heat recovery, while it ranges from 1.521 to 1.834 when the engine waste heat is recovered. It indicates that the total PER can be significantly improved by recovering the engine waste heat.

The Effect of the Isolator Design on the Efficiency of Rotary Piston Compressors

The current work investigates the relationship between the shape of an isolator of a concentric rotary piston compressor and the secondary peak pressure developed during each operating cycle. This peak pressure is developed when the piston passes through the isolator cavity, and it is negative for compressor efficiency. The aim of this paper is to identify the isolator cavity shape that minimizes this secondary peak to improve compressor efficiency. This study covers five different cavities that may be used in such compressors. Contrary to our expectations, the conclusion is that the best geometry is the one that can be manufactured with CNC machining. The geometry that can be manufactured with 3D printing also produces a significantly lower secondary peak pressure, but it is not cost-efficient. Another limitation of the 3D printing design is the thin walls that this cavity creates. Very thin walls may cause significant deformation during the compression cycle. The conclusion is that there is a CNC machining design that is cost-efficient and allows for higher compressor performance.

Функциялық тюнингтің түрі ретінде жаңа трибожұптасу қолданылуы бар цилиндр-порнешьдік топты жөндеу жинағын әзірлеу

This article presents a new design of an innovative repair kit for vehicles. New principles and effects for reducing friction in vehicle joints are considered. The main difference of the new solution is the use of spring rings instead of ordinary compression piston rings. According to the proposed solution, a physical model was created and a patent was obtained. The main purpose of functional tuning is to increase the durability of the engine and technical indicators of the engine. The article describes the original spring rings and their working principles. In the preliminary works, it is planned to install the new technology in a practical round on an internal combustion engine and obtain new data as a result of the experiment.

Modeling and parametric optimization of a liquid piston compressor with inner cooling tubes

This work proposes a new configuration of liquid piston compressors and a methodology for their optimization, with special attention to heat removal from the compressing gas, in order to minimize the mechanical work required for the compression process. The adopted approach starts with the solution of the governing equations through a 0D model (lumped approach). A new correlation for the heat transfer coefficient is presented to calculate the sensible heat transfer from the compressing gas to the cooling liquid. The results of the 0D model are validated by comparison with experimental and numerical data from the literature and with performed CFD calculations. In the proposed geometric configuration, heat is removed from the compressing gas through a tubes bundle inserted in the compression chamber, the liquid cooling medium flowing inside the tubes. This geometric configuration was chosen because it is simple to design and common materials and manufacturing processes can be used for its manufacturing. In addition, no regeneration of the inserts is required from cycle to cycle, making that configuration ideal for cyclic operation. The parametric study performed focuses on the dependence of the overall efficiency on the number and diameter of the cooling tubes and the speed of the liquid piston. It is found that the overall efficiency is highest for a given number of tubes with at a specific diameter, and that the combination of a few cooling tubes with a larger diameter and a higher piston speed gives the best overall efficiency.

Dynamic and energy analysis of a liquid piston hydrogen compressor

Liquid piston compressor is the most promising compressor to be used for hydrogen-refueling stations. However, their energy transfer and the energy dissipation processes of are poorly studied and not well understood. In this paper, a new energy analysis method for an ionic-liquid type liquid piston compressor is proposed. In the compressor section, porous media is used to promote heat transfer from the hydraulic oil during the compression process. A mathematical model has been formulated considering the heat transfer and damping effects of the porous media on the compressor performance. Moreover, the compressibility of the hydraulic oil and its overflow loss on the compressor performance were also established. In the model, the seven stages of the entire working cycle of the compressor were look into in detail, alongside with its energy efficiency. The results show that the key parameters governing the energy efficiency of the compressor are the heat transfer efficiency of the compressor and the overflow losses of the hydraulic oil.

Laser texturing of piston ring for tribological performance improvement

The radial surface coating layer of compression piston rings is used to improve their wear resistance during the internal combustion engine operation. However, at top dead centers, the friction coefficient of the piston ring-cylinder liner pair is detrimental to the engine’s tribological performance. In this work, dimples with different texture dimensions and densities were tested in a home-developed tribometer. The friction coefficient was measured for all samples, and for those with the best results, their wear resistance was assessed. The texture with an aspect ratio of 0.25 and a density area of 15% reported the best tribological results.