Search Results (1,908)

Centrifugal compressors (CCs) are key components of marine power plants (MPPs), supporting engine boosting, boil-off gas (BOG) handling on liquefied natural gas (LNG) carriers, and auxiliary services such as heating, ventilation, and air conditioning (HVAC). However, recent publications are often fragmented by domain (aerodynamics, mechanical design, standards, and digitalization), complicating cross-domain engineering decisions for marine duty cycles. This structured review follows an explicit protocol to synthesize peer-reviewed studies (2015–2025) retrieved from Scopus and Web of Science and organizes the evidence by application class: turbocharger-integrated stages for marine diesel and gas-turbine engines, LNG/BOG compression trains, and auxiliary onboard services. The synthesis consolidates (i) aerodynamic KPIs (pressure ratio, efficiency, surge and stall margins, and operating range), (ii) mechanical and lifecycle enablers (seals, bearings, and rotordynamics), and (iii) quantified impacts of digital methods (control, diagnostics, and digital twins). Reported trends include single-stage pressure ratios of ~5.4–5.7, multistage overall pressure ratios exceeding 10, and surge-margin improvements of ~40–44% associated with advanced diffusers as well as casing and endwall treatments. Industrial case studies (non-marine) report downtime reductions of ~25–35% and maintenance-cost reductions of ~25%, while evaluated diagnostic datasets show high accuracy. Key gaps remain in marine-specific validation datasets and harmonized testing and data standards. Full article

The hydraulically driven piston compressor is a state-of-the-art solution for compressing hydrogen to pressure levels up to 100 MPa and even beyond, especially for use in hydrogen refueling stations. Based on the technical data of a few commercial hydraulically driven piston systems for hydrogen compression, thermodynamic calculations are developed in this paper, and a preliminary indicator, the compression-to-electric power ratio (CEPR), is assessed. In order to justify calculated CEPR values no greater than 0.42 for the analyzed compression units, attention is paid to the hydrogen compression duty, and the instantaneous power is drawn based on a simple but effective procedure. In detail, the instantaneous power profile has a peak value approximately double that of the average power, and this peak is maintained for almost half of the working period. According to this result, the electric motor must be sized correctly. Thus, it might seem over-configured if compared to the average compression power, hence the relatively low CEPR values. Finally, in order to support the current assessment of the instantaneous power, considerations about the control system for piston movement inversion are reported. Full article

This study examines the sectoral dynamics of natural gas consumption in Colombia by applying additive and multiplicative Holt–Winters exponential smoothing models. The analysis covers the main demand segments (Thermal Generation, Industrial, Residential, Refinery, Compressed Natural Gas for Vehicles (GNVC), Commercial, Petrochemical, and SNT Compressor Stations) using official monthly data from the Colombian Mercantile Exchange for the period April 2020 to July 2025. Model configurations were optimized by minimizing the Mean Absolute Error (MAE), Mean Absolute Percentage Error (MAPE), and Mean Squared Error (MSE) to identify the most appropriate structure for each sector. The results confirm that natural gas consumption in Colombia does not follow a uniform seasonal pattern. Instead, each segment exhibits distinct dynamics shaped by operational conditions, production schedules, mobility-related behavior, or logistical planning. The Thermal Generation sector was best represented by the multiplicative model, reflecting proportional variability associated with electricity dispatch and system-level operational changes. In contrast, the Industrial, Residential, GNVC, Commercial, and SNT Compressor Stations sectors showed superior performance under the additive model, consistent with relatively stable or constant-magnitude seasonal effects. The Petrochemical and Refinery sectors displayed short-term cyclical behavior, with model accuracy depending on the performance metric prioritized. These findings demonstrate that energy forecasting must incorporate the structural heterogeneity of demand systems rather than treating natural gas consumption as a homogeneous aggregate. Practically, the results provide insights for improving supply planning, contract allocation, and regulatory segmentation. The study also offers a replicable methodological basis for forecasting in emerging economies characterized by diverse consumption profiles. Full article

This study presents a hybrid modeling framework integrating a deep learning-based black-box model of a CO₂ heat pump with a physics-based white-box system model developed in Modelica. The approach reduces the complexity of thermodynamic modeling while maintaining system-level accuracy. A deep neural network (DNN) trained on measured data predicts outlet temperatures and compressor power, coupled with the Modelica model through the Functional Mock-up Unit (FMU) interface. The framework was applied to a ground-source CO₂ heat pump system in Oslo, Norway, to evaluate hysteresis-based control strategies with different return temperature ranges (20–50 °C, 20–55 °C, 20–70 °C) and flow rates (1.3–1.5 kg/s). Results showed similar total heating but 25% lower compressor energy use for the 20–50 °C, 1.5 kg/s case compared to 20–70 °C. Temperature-based control improved coefficient of performance (COP) of the heat pump, while narrower temperature ranges and lower flow rates enhanced tank stratification and heat utilization. The findings demonstrate the effectiveness of the hybrid model for dynamic simulation and control optimization of CO₂ heat pump systems. Full article

As hydrogen mobility gains increasing importance, the number of hydrogen refueling stations (HRSs) worldwide is expanding rapidly. Hydrogen compression is a critical component of every HRS, exerting a direct and decisive influence on operability, performance, economic viability, downtime, safety, and public acceptance. Given this central role, this work presents a comprehensive overview of the hydrogen compression landscape, critically examining both conventional mechanical systems—such as piston and diaphragm compressors—and emerging non-mechanical technologies, including electrochemical and metal hydride compressors. The analysis also addresses novel hybrid approaches that combine methods to exploit their respective strengths. Each technology is assessed against a consistent set of practical criteria, encompassing not only fundamental performance metrics such as maximum discharge pressure and flow capacity but also key considerations relevant to real-world deployment. This review provides a detailed comparison of all hydrogen compression technologies with respect to energy efficiency, maintenance needs and intervals, capital expenditures (CAPEX), operating expenditures (OPEX), and Technology Readiness Level (TRL). Additional factors—including physical size, noise levels, and effects on hydrogen purity—are also evaluated, as they strongly influence the suitability for applications in urban or remote areas. By synthesizing recent scientific literature, industry data, and applicable technical standards, this work develops a structured multi-criteria framework that translates technical insights into practical guidance and a clear technology selection roadmap. The overarching objective is to equip engineers, station developers, operators, and policymakers with the knowledge needed to make informed and optimized decisions about hydrogen compression during HRS planning and design. Full article

This study advances the performance of a tandem-blade centrifugal compressor through a parametric Computational Fluid Dynamics (CFD) methodology integrated with Response Surface Methodology (RSM). Numerical simulations were executed by solving steady-state Reynolds-Averaged Navier–Stokes (RANS) equations utilising the Shear Stress Transport (SST) k-ω turbulence model on a validated structured hexahedral mesh. Local sensitivity analysis identified the hub outlet angle and hub inlet angle as the primary geometric parameters affecting pressure ratio and isentropic efficiency, respectively. Flow-field visualisations confirmed that the tandem configuration effectively re-energises the boundary layer, thereby reducing separation and enhancing pressure recovery. Using a Multi-Objective Genetic Algorithm (MOGA), an optimal blade design comprising 22 blades was determined, achieving a maximum isentropic efficiency of 95.23% and a total pressure ratio of 1.416. These findings provide valuable quantitative insights for the optimal design of tandem impellers and highlight the effectiveness of integrating CFD-based sensitivity analysis with multi-objective optimisation techniques. Full article

High-bypass ratio engines are currently among the most investigated solutions to achieve efficiency benefits and noise reduction in gas turbine engines. When equipped with a gearbox, these engines enable an optimized operation of the fan and of the low-pressure core, resulting in reduced weight and fuel consumption. The higher spool speed allows higher pressure ratios per stage, and consequently a reduced stage count. However, all this contributes to an enhanced sensitivity of the engine components to the development of secondary flow structures and separations, with a consequent impact on the aerodynamic performance and stability. In this context, an experimental campaign was conducted at the von Karman Institute for Fluid Dynamics on a highly loaded axial compressor representative of the first stage of a modern booster. The aim was to identify the flow features responsible of the performance loss at the operating points and speeds considered more critical in terms of rotor inlet incidence. To this end, time-averaged instrumentation was employed to characterize the performance and to retrieve the distribution of flow quantities at different axial positions within the stage, while fast-response probes allowed for the detailed characterization of the rotor outlet flow field. Unsteady 3D simulations complemented the experimental results and supported this interpretation, especially in regions with limited instrumentation access. The experimental and numerical results emphasized the role of the secondary flow structures developing near the hub wall as the main drivers for aerodynamic stall, due to the enhanced loading in this blade region. Full article

An investigation was conducted into the effectiveness of heat shields in an aero-engine compressor casing to slow down thermal time constants. The investigation used a combination of experimental measurements from a full-size compressor casing rig, combined with numerical analysis using CFD and thermal modelling. Experiments were performed on a compressor casing both with and without heat shielding in order to determine the heat shield effectiveness. Temperature measurements were taken throughout the casing in order to determine the thermal time constants. The experimental data was then used to validate a thermal model and CFD simulations of the compressor casing. The modelling allowed the heat transfer coefficients in the compressor casing to be determined from the experimentally measured time constants. It was found that the heat shields gave an increase in thermal time constant at each measured location. With a doubling in the time constant at some locations compared to the unshielded case. It was also found that the heat shields need to be fully sealed, as leakage flows significantly reduce their effectiveness. Full article

Ceramic Matrix Composites (CMCs) have emerged as a structural material alternative to nickel superalloys for high-pressure turbines (HPT) components operating at high temperature, like shrouds. Despite the outstanding thermal stability of the CMCs, limited cooling is still necessary due to the extreme thermal operating conditions necessary to maximize engine performance and minimize fuel consumption. The design of CMC components, indeed, must consider a maximum service temperature that should not be exceeded to avoid damage and accelerated oxidation. The cooling, on the other hand, may induce the formation of thermal gradients and thermal stresses. In this work, different design options for the cooling system are investigated to minimize the thermal stresses of an HPT shroud-like geometry subjected to maximum temperature constraints on the material. Cooling is obtained via colder air jet streams (air taken from the compressor), whose impact position (the surface where the cold air impacts the component) has a different effect on the temperature field and on the induced stress field. Besides stress evaluation with different cooling systems, an ONERA damage model is investigated at a key location to potentially take into account stress components acting simultaneously and potential stiffness degradation of the CMC. Finally, the design evaluation of potential discrete crack propagation is discussed. A standard cohesive elements approach has been compared with a brittle element death approach. The results showed that the cohesive element approach resulted in shorter crack propagation, underestimating the actual crack behavior due to the embedded stiffness degradation method, while the element death returned encouraging results as a quicker, less complex, but still accurate design evaluation. Full article

Maintaining stable pressure in the oxidation–compressor section of purified terephthalic acid (PTA) plants is essential for ensuring efficient and reliable operation. Conventional single-loop proportional integral derivative (PID) controllers frequently perform inadequately because of the large pressure drop between the compressor discharge and reactor inlet, which should ideally remain at approximately 1.2 kg/cm² above the reactor pressure setpoint but can reach up to 2.8 kg/cm² due to downstream vapor-phase disturbances. Through this study, we aimed to address this issue by developing a robust cascade pressure control strategy to improve pressure stability and reduce energy losses. Dynamic process models were constructed using system identification techniques to represent real plant behavior, and the best-performing models—identified based on minimum root mean square error (RMSE)—were determined using the Wade method for pressure indicating controller PIC-101, the Lilja method for PIC-102, and the Smith method for pressure differential indicating controller PDIC-101. The proposed cascade configuration was tuned using the Lopez ISE method and evaluated under representative disturbance scenarios. The results showed that the cascade controller significantly improved pressure control, enhanced disturbance rejection, and lowered the risk of reactor shutdowns compared with the conventional proportional-integral PI-based approach. Overall, this study demonstrated that model-driven cascade control can enhance robustness, operational reliability, and energy efficiency in large-scale PTA oxidation processes. Full article

The suction and discharge reed valves are critical components of reciprocating refrigeration compressors, as their dynamic behavior strongly affects the compressor performance. This study investigates the interaction mechanism between unsteady flow characteristics and valve dynamics in a reciprocating refrigeration compressor. A 3D fluid–structure interaction (FSI) simulation model was developed, and its reliability was validated by comparing the simulated in-cylinder pressure and suction valve lift with the corresponding experimental measurements. The validated model was subsequently utilized to analyze the evolution of unsteady flow characteristics and valve deformations. Furthermore, a series of FSI simulations was performed to examine the influence of suction pressure, rotational speed, clearance volume ratio, suction valve plate thickness, and discharge valve plate thickness on valve dynamics and compressor performance. The results indicated that suction pressure, rotational speed, and clearance volume ratio all exerted a significant influence on the dynamics of both the suction and discharge valves. Variations in suction valve plate thickness exhibited a minor influence on the dynamic behavior and flow resistance of the discharge valve, whereas adjustments to discharge valve plate thickness had almost no impact on those of the suction valve. This weak coupling characteristic provides flexibility for the independent optimization of the suction and discharge reed valves. The findings of this study lay a solid foundation for optimizing valve design and improving compressor performance. Full article

Since the compressor system in underground gas storage (UGS) facilities operates under highly dynamic and complex injection conditions, traditional rule-based operation and mechanism-based modeling approaches prove inadequate for meeting the stringent requirements of high-accuracy prediction under such variable conditions. To address this, a data-driven two-phase prediction framework for compressor energy consumption is proposed. In the first phase, a convolutional neural network with efficient channel attention (CNN-ECA) is developed to accurately forecast key operating condition parameters. Based on these outputs, the second phase employs a compressor performance prediction model to estimate unit energy consumption with improved precision. In addition, a hybrid prediction strategy integrating a Transformer architecture is introduced to capture long-range temporal dependencies, thereby enhancing both single-step and multi-step forecasting performance. The proposed method is evaluated using operational data from eight compressors at the Xiangguosi underground gas storage. Experimental results show that the framework achieves high prediction accuracy, with a MAPE of 4.0779% (single-step) and 4.2449% (multi-step), outperforming advanced benchmark models. Full article

In the aerospace field, the BT25y titanium alloy is recommended as a candidate material for manufacturing compressor discs and rotor blades of aircraft engines. The influence of hot deformation parameters on the microstructural evolution, recrystallization softening, and globularization mechanism of the BT25y alloy with an initial lamellar structure was studied. Furthermore, the coupling relationship between dynamic recrystallization and lamellar globularization was explored by means of EBSD, SEM, and TEM techniques. The experiment results indicate that the characteristics of initial lamellar α, α/α sub-grain boundaries within α lamellae, and the α/β phase boundary show significant variations due to the formation of equiaxed α grains during hot deformation. As the strain rate increases, the recrystallization mechanism of α phase gradually shifts from CDRX softening characterized by sub-grain evolution and lamellae fracture, to DDRX softening characterized by grain boundary arching and sub-grain boundary bridging. As the deformation temperature increases, the intense thermal activation promotes the accumulation of distortion storage energy, providing enhanced driving force for the occurrence of dynamic recrystallization. The research results will contribute to a deeper understanding of the relationship between dynamic recrystallization and lamellar globularization, providing theoretical guidance for the deformation process optimization and mechanical property control of the BT25y alloy. Full article

We report a dispersion-controlled Yb-doped fiber chirped pulse amplification (CPA) system incorporating a tunable chirped fiber Bragg grating (CFBG) stretcher and a single-grating transmission compressor for dynamic compensation of power-dependent nonlinear effect. During the pulse amplification, the CFBG introduces adjustable third-order dispersion (TOD). By tuning the initial TOD provided by CFBG from −0.1965 ps³ at 2.37 W to −0.1791 ps³ at 9.65 W, residual TOD is efficiently compensated with the power-dependent nonlinear effect. As a result, by optimizing the dispersion balance at each output power, nearly constant femtosecond pulses with a duration of 250 fs are obtained over the entire power range, confirming effective control of nonlinear and dispersive effects in the amplification. The high-quality 1030 nm pulses enable efficient second-harmonic generation (SHG) in a type-I BBO crystal, producing 3.56 W femtosecond output at around 515 nm with a pulse duration of 190 fs, close to the Fourier transform limit. These results demonstrate a robust approach to generating high-power and temporal coherent ultrafast pulses suitable for precision micromachining and two-photon polymerization. Full article

This work presents a model that calculates temperature-dependent heat pump performances as a circular heat pump process as a reference model. The model is then systematically simplified by making assumptions or applying functional approximations to key variables. These simplifications include linearization of the substance database calculations and modeling of the compressor efficiency as a function or constant. The effects of these simplifications on the accuracy of results are quantified and compared with other modeling approaches from the literature suitable for linear and bilinear optimization issues. Initial comparisons show that the root mean square error of the model achieves better results than comparable methods. While the root mean square error of the COP in linearized models in the compared literature ranges from 0.433 to 1.233, it can be improved to a maximum of 0.335 using the approach presented. Full article