Compression System Research Articles

Techno-economic analysis of green hydrogen production, storage, and waste heat recovery plant in the context of Nepal

Alkaline water electrolysis (AWE) operated by surplus electricity is suitable for producing green hydrogen in Nepal. Simulation models are built using DWSIM software for AWE, multistage compression, and the Organic Rankine Cycle (ORC). The AWE system's Capital Expenditure (CAPEX) is determined to be $47 million and Operational Expenditure (OPEX) of $7.65 million/year. The storage system, including the multistage compression system and Type IV cylinders, has a CAPEX of $52 million and an OPEX of $17 million/year. The ORC has a CAPEX of $500,000 and an OPEX of $200,000/year. The thermal power generated from AWE and multistage compression can be converted to electricity by the ORC and supplied to the AWE system. This process decreases the Levelized Cost of Hydrogen (LCOH) from $3.5141/kg over 5 years to $3.4725/kg over 25 years. The techno-economic analysis performed confirms the feasibility of implementing these plants in Nepal.

Design and operation of an adiabatic compressed air energy storage system incorporating a detailed heat exchanger model

Heat exchangers (HEXs) are among the key components of adiabatic compressed air energy storage (A-CAES) systems. However, the existing HEX models applied in the A-CAES systems are overly simplistic, limiting research regarding design and operational simulation. For the first time, this study incorporates a comprehensive HEX model, including calculations for geometric dimensioning, heat transfer, and pressure drop, into the A-CAES system model; in addition, a novel layered, interactive system design and operational simulation algorithms are developed. The developed models and algorithms can facilitate the design process and yield reasonable operational simulation results with only basic parameters. The design algorithm can determine all key parameters of the system and assess the effect of the HEX pressure drop and heat transfer area on the system performance. The operational simulation algorithm considers the performance of all key equipment under off-design conditions. The design exergy efficiency and daily net income of the system are 73.15 % and $26,998, respectively; however, these values decrease during operation to 72.15 % and $25,034, respectively. A comprehensive analysis of the key parameters during operation revealed that the primary causes for the degradation were the sliding pressure in the energy storage process and variations in the air storage tank parameters.

Generation of sub-150 fs, 10 W-class, pedestal-free 2.07 µm ultrashort pulses using a cascade compression system.

We report high-power pedestal-free ultrashort pulses in a cascade compression system. In the self-compression stage, the 2 µm ultrashort pulses with 123 fs duration and up to 21.7 W output power were obtained in a 0.3 m 50 µm core diameter fiber. It is the highest self-compressing power ever obtained in a silica fiber with an all-fiber 2 µm laser amplifier as the pump source. To obtain purer pedestal-eliminated pulses, we further increase the fiber length to 1 m to trigger the soliton self-frequency shifting (SSFS) effect. By employing an enhanced SSFS technique based on third-order dispersion (TOD) and filtering out the unshifted signal light, we finally achieved sub-150 fs, 10 W-class, 1.2-MW peak-power, pedestal-free 2.07 µm ultrashort pulses. This is also the highest, to the best of our knowledge, power and energy of Raman soliton obtained by SSFS in an ordinary silica fiber.

Pathway to Decarbonization Through Industrial Energy Efficiency: Micro and Macro Perspectives from Compressed Air Usage

Energy audits directly provided the industrial sector with reduced energy costs and avoided emissions. Still, they also lead to far-reaching indirect and induced local, regional, and national benefits. This paper aims to present the techno-economic-environmental analysis to achieve decarbonization through implementing industrial energy efficiency at micro and macro levels. An integrated techno-economic-environmental methodology is developed. Case studies of micro-level carbon reduction efforts through industrial energy efficiency technologies are presented. The broader macroeconomic and environmental effects of technology on society are analyzed using data from 206 energy audits of industrial compressed air systems conducted over 13 years. The impacts show that energy-efficient improvements lead to direct cost savings for manufacturers, boost economic activity across sectors, and affect carbon dioxide emissions both short-term and long-term in the region. Given their extensive benefits, energy audits significantly influence policymaking. We devised a methodology to link micro-level energy audit data with macroeconomic and environmental analyses to quantify these cascading benefits. The economic scenario analysis shows that $228 M has been saved from direct industrial energy savings from implementing all compressed air recommendations in the studied periods and the region. In addition, the investment made through manufacturers would create 2,025 jobs and $383 M annually, cascading regional economic impacts. The environmental analysis shows that the regional manufacturers have directly avoided about 2.8 M metric tons of carbon dioxide emissions.

Evolution of deformation structures in CrCoNiSi0.3 medium entropy alloy subjected to high-strain-rate and quasi-static compressive deformation

The objective of the present study is to fundamentally explore the evolution of deformed structures of CrCoNiSi0.3 medium entropy alloy subjected to high-speed compression deformation with true strains of 0.16, 0.33, and 0.46 (via split Hopkinson pressure bar system, strain rate of ∼6 × 103 s−1, denoted as HSR deformation), and quasi-static compression deformation with true strains of 0.20, 0.30 and 0.50 (via MTS compression system, strain rate of ∼10−3 s−1, denoted as LSR deformation). From the comparison between the results of HSR and LSR samples, it clearly indicates that the formation of deformation nanotwins is promoted under the HSR deformation and enhances the work hardening effect in the early stage of deformation; as the HSR deformation proceeds, the nanotwins effectively provide the dynamic Hall–Petch effect, leading to an increase in flow stress beyond the stress required for HCP phase transformation. The HCP phase also induces a stronger work hardening capacity at the late stage of deformation. Profuse deformation nanotwins and HCP phase promoted by HSR deformation result in a strong work hardening effect. Furthermore, the flow stress of the HSR deformed sample with a true strain of 0.46 is 1536 MPa, which is about 36% higher than that of the LSR deformed sample with the same true strain, 1102 MPa. It is clear that under the HSR deformation, the defect structures including deformation nanotwins and ultra-thin HCP platelets are much more favorably generated, greatly improving the working capacity.

3D information transmission of a computer-generated hologram using a quantum compensation hybrid neural network.

A computer-generated hologram compression and transmission system is designed. The system uses a hybrid neural network based on quantum compensation to compress and decompress computer-generated holograms and uses a quantization method and Huffman coding to encode the compressed holograms for transmission. The receiving side decodes and decompresses the data stream to obtain the recovered hologram, which can be used to reconstruct the original object information for 3D image display. Our numerical experiments show that quantum compensation can improve the quality of the reconstructed image. Furthermore, we introduce a quantum compensation factor to describe the strength of quantum compensation and verify experimentally that the quantum compensation module may drive the conventional neural network to converge in fewer training epochs.

Introduction of a carbon footprint assessment in the oil and gas facility life extension decision-making process

In large oil and gas producing countries, extraction and processing activities, including upstream activities, can represent a large share of domestic emissions. As oil fields approach their expected service life and reach depletion, energy use and GHG emissions increase per unit of produced oil, shifting operations away from their optimal point. Thus, it is paramount that oil field life extension decisions account for energy use and GHG emissions. However, many facilities are having their service life extended without considering this energy inefficiency and previous life extension decision making studies have neglected GHG emissions. Addressing this issue, this paper proposes the inclusion of a carbon footprint assessment within the evaluation of oil and gas offshore production facility life extension. The carbon footprint assessment adds an environmental lens to the evaluation of ageing, formerly evaluated according to material degradation, obsolescence and organizational issues. An eleven-stage framework is proposed to systematize the ageing related carbon footprint assessment and support life extension decision-making: (1) Objective definition, (2) Scope definition, (3) Field conditions description, (4) Scope breakdown into manageable portions, (5) Detailed data collection for each process and subsystem, (6) Input and output definition for each process and subsystem, (7) Process modelling, (8) Methodology definition for energy demand and inefficiency estimate, (9) Monitoring indicator definition, (10) Performance evaluation, and (11) Interpretation of results. The proposed framework is applied to a hypothetical case study, developed with data from a typical oil and gas offshore production platform operated in Brazil. Two LE improvement strategies were simulated, i.e. reducing the number of gas turbines, and increasing the export of natural gas. Both alter the modus operandi of the compression system and do not require additional equipment installation. These strategies resulted in a combined reduction of 922,000 tCO2 during the extended 10-year operation. This outcome demonstrates that by applying the framework opportunities for reducing energy use and GHG emissions during life extension can be identified and quantified, facilitating life extension decision-making.

Compression Wraps—Providing Solutions for Complex Lymphatic Presentations

Compression is the cornerstone of treatment for lymphoedema; however, in patients with Stage III lymphoedema that causes a significant alteration of limb shape and size, additional creative problem solving is required in order to find a solution that fits the person, their limb and their personal circumstances. Medical adaptive compression (MAC) systems provide solutions to complex situations. We present two cases of individuals who completed an inpatient rehabilitation stay for intensive treatment of their lymphoedema and were fitted with MAC devices to ensure long-term success.

Performance analysis of a new compressed air energy storage system coupled with the municipal solid waste power generation systems

In order to improve the performance of the compressed air energy storage (CAES) system, a novel design is proposed: the CAES system is combined with the municipal solid waste power generation systems, including a waste incineration power generation system and a biogas power generation system. During the charging process, the feedwater and the condensate from the waste incineration power generation system are used to cool the compressed air. During the discharge process, the released compressed air is heated by the flue gas from the waste incineration power generation system, and the high-temperature compressed air works in the expander. Finally, the expanded air from the expander is fed into the combustor of the biogas power generation system, thus replacing the compressor of the gas cycle. Through the system integration, the efficiency of the CAES system is improved, and some equipment of the original CAES system is reduced. Based on the systems simulation, energy analysis, exergy analysis, economic analysis, and sensitivity analysis are performed. As a result, for the CAES subsystem, the round-trip efficiency, the energy storage density, and the exergy efficiency can reach 75.32 %, 14.10 MJ/m3, and 74.31 %. Besides, the dynamic payback period can reach 6.82 years.

Power-to-X system utilizing an advanced solar system integrated with a thermally regenerative electrochemical cycle

This article discusses power-to-X technology by proposing an advanced system to generate green electricity and hydrogen. The proposed system is powered by an advanced concentrated parabolic photovoltaic thermal (CPV/T) hybrid system. A proton exchange membrane (PEM) water electrolyzer system is used for the hydrogen production process, with a multistage compression system to increase hydrogen pressure and regulate hydrogen temperature. Additionally, a heat recovery system is employed through the thermally regenerative electrochemical cycle (TREC). A parametric analysis was performed based on thermal resistance to investigate the effect of solar radiation, Reynolds number, lengths of both the receiver side and tube and ambient temperature. A mathematical model was developed and validated to investigate the integrated system performance. CPV/T achieved a maximum system efficiency of 85.4% at 1000 W/m2 and a side length of 0.2 m, with electrical and thermal contributions of 21.1% and 64.3%, respectively. With a tube length of 20 m, the maximum hydrogen flow rate reached 280 kg/h, requiring 2.5 TJ/h for production under a pressure of 750 bar. The TREC system showed a maximum electrical production contribution of about 25.4% at a Reynolds number equal to 3000 compared to the contribution of CPV/T cells.

Off-design characteristics and operation strategy analysis of a compressed carbon dioxide energy storage system coupled with a combined heating and power plant

To advance renewable energy development, it is crucial to increase the operational flexibility of power plants to consume renewable energy. Supercritical compressed carbon dioxide energy storage (SC-CCES) system is considered as a promising solution. This paper develops thermodynamic and off-design models for system components to formulate the system off-design model. The round-trip efficiency (RTE), system power efficiency (SPE), total exergy efficiency (TEE), and energy storage density (ESD) are defined to analyze the off-design performance of the system under two operation strategies. The results indicate that the system achieves the RTE of 32.44 %, SPE of 67.58 %, TEE of 43.26 %, and ESD of 1.73 kWh/m3 under the rated operating condition. The input power, output power, heat transfer rate, and mass flow rate during the charging and discharging process are proportional to the load level for both operation strategies. The RTE and TEE of the system vary inversely with the charging load level and directly with the discharging load level. The ESD is independent of the charging load level and increases with the discharging load level. The speed regulation-throttling regulation (SR-TR) operation strategy demonstrates superior system performance and a broader range of operating conditions.

Development and comprehensive thermo-economic analysis of a novel compressed CO2 energy storage system integrated with high-temperature thermal energy storage

This study introduces an innovative compressed CO2 energy storage (CCES) system poised to significantly enhance the management of fluctuating renewable energy sources. Unlike traditional system layouts, a high-temperature thermal energy storage (HTES), an ejector cycle and a flash process are adopted in the system and innovatively integrated into its charging and discharging process. These above methods aim to reduce geographic limitations and improve round-trip efficiency. Thermodynamic and economic models are established to conduct a comprehensive evaluation, engaging in detailed parameter analysis followed by multi-objective optimization. The analysis indicates that increasing turbine inlet pressure and temperature significantly improves system performance. While increasing flash pressure and the temperature of low-pressure storage benefit round-trip efficiency (RTE) and levelized cost of electricity (LCOE), it negatively impacts the energy storage density (ESD). Additionally, setting the ejector back pressure at approximately 7.5 MPa optimizes performance. Multi-objective analysis indicates that the optimal low-pressure storage temperature is approximately 295.07 K, with the associated flash pressure and ejector back pressure set at 3.94 MPa and 7.48 MPa, respectively. Under these conditions, the proposed system achieves the optimal RTE, ESD and LCOE of 50.43 %, 16.60 kWh/m³, and 0.0992 $/kWh, respectively. Compared to other similar systems, the proposed system exhibits preferable balance performance.

Performance analysis of a novel isothermal compressed carbon dioxide energy storage system integrated with solar thermal storage

The significant increase in renewable energy generation will lead to the unstable operation of the power system. Compressed carbon dioxide energy storage (CCES) is a promising energy storage technology, which can smooth the output of renewable energy. However, one of the disadvantages of conventional CCES is the need to store compression heat, which leads to the complex structure of heat storage units. In this paper, an isothermal CCES system integrated with solar thermal storage is proposed and modeled. The parameter variations of work fluids in the pressure vessels with time and the thermodynamic properties and economics of the system are analyzed. The results show that the round-trip efficiency is 107.14 %, the energy storage density is 5.174 MJ/m3, and the levelized cost of electricity is 0.142 $/kWh. The component with the highest exergy destruction is the regenerator, followed by the LP units. The combination of liquid spray technology can decrease the highest temperature of carbon dioxide in the pressure vessel from 358.80 K to 309.39 K and increase the isothermal compression efficiency from 78.72 % to 92.26 %. Increasing the liquid spray flow rate and decreasing the hydraulic pump flow rate can both make the actual compression process closer to the isothermal process.

Information Density Enhancement Using Lossy Compression in DNA Data Storage.

This study develops two deoxyribonucleic acid (DNA)lossy compression models, Models A and B, to encode grayscale images into DNA sequences, enhance information density, and enable high-fidelity image recovery. These models, distinguished by their handling of pixel domains and interpolation methods, offer a novel approach to data storage for DNA. Model A processes pixels in overlapped domains using linear interpolation (LI), whereas Model B uses non-overlapped domains with nearest-neighbor interpolation (NNI). Through a comparative analysis with Joint Photographic Experts Group (JPEG)compression, the DNA lossy compression models demonstrate competitive advantages in terms of information density and image quality restoration. The application of these models to the Modified National Institute of Standards and Technology (MNIST) dataset reveals their efficiency and the recognizability of decompressed images, which is validated by convolutional neural network (CNN) performance. In particular, Model B2, a version of Model B, emerges as an effective method for balancing high information density (surpassing over 20 times the typical densities of two bits per nucleotide) with reasonably good image quality. These findings highlight the potential of DNA-based data storage systems for high-density and efficient compression, indicating a promising future for biological data storage solutions.

Comparative Analysis of Diagonal and Centrifugal Compressors with Synergy Theory in Compressed Air Energy Storage System

Comparative Analysis of Diagonal and Centrifugal Compressors with Synergy Theory in Compressed Air Energy Storage System

Global selection appraisal study for heat pump system of electric vehicle based on energetic, economic, and environmental analysis

The development of electric vehicles (EVs) exhibits rapid and remarkable progress nowadays, serving as a crucial route to accomplish the target of mitigating greenhouse gas emissions. As an integral part of the thermal management system oriented toward electric vehicles, the heat pump air conditioning system for electric vehicles is the result of a comprehensive choice that trades off the cooling and heating performance, environmental performance and economic cost. Particularly, different regions around the world suffer varying cooling and heating challenges due to the complicated climatic characteristics. Thus the most suitable refrigerant and system cycle structure may differ. This paper focuses on evaluating both the refrigerants and cycle structures to screen the most suitable choice. According to the climate conditions of different cities, the annual energy consumption, life cycle climate performance, and economic cost of the basic system (Base), two-stage compression system (TSC,IC), and vapor injection (VI) system with CO2, R134a, and R1234yf refrigerants respectively, are quantitatively analyzed and evaluated. Subsequently, through comparative analysis, a comprehensive selection map for heat pump systems in electric vehicles worldwide is developed and the most suitable heat pump air conditioning system for each cites is determined. The results can provide a selection reference and decision-making for the air conditioning system of electric vehicles from regional considerations. It was found that the CO2 HPACVI was recommended for cold regions to meet both environmental and economic requirements. In warm region, the R1234yf HPACBase system was recommended to be used. For regions transitioning from cold to warm climates, the R1234yf HPACVI system was suggested. In hot region, the R1234yf AC system was recommended.

Research on hydraulic variable pressure pumped compressed air energy storage system

Abstract To cope with the problems of large pressure variation, large throttling loss of the existing pumped compressed air energy storage system, a new hydraulic variable pressure pumped compressed air energy storage system is proposed in this paper. The key components include a variable-speed pump turbine, a hydraulic potential energy transfer device and a water-gas compatible tank. For the proposed system, a thermodynamic model is established. And its correctness is verified by comparing it with measured data. Then, the charging and discharging simulation is carried out. Finally, the variation process of each key parameter of the system is revealed. It is found that the energy efficiency of the system is high, reaching 58.2%, and the energy density is 0.36 kW·h/m3. Through the hydraulic potential energy transfer device, the pressure variation of 2.2 MPa in the tank is converted into the head variation of about 60 m (0.6 MPa) at the variable-speed pump turbine, which improves the operating efficiency of the hydraulic machinery. This technology can provide support for the development of energy storage technology.

Thermal analysis of a gas-liquid compressed carbon dioxide energy storage system

Abstract In recent years, compressed CO2 energy storage (CCES) systems have attracted increasing attention, because the high-pressure storage tanks in the CCES systems are relatively small, thereby reducing investment costs and improving geographic construction flexibility. In this paper, we propose a gas-liquid CCES system that has strong industrial feasibility. A comprehensive thermodynamic evaluation and parametric analysis were performed for this system. The results show that the efficiency is 72.99% and the storage pressure is an important parameter influencing the thermal performance of this system, and the reasons behind it are explored.

On the state principle of classical thermodynamics

We discuss the state principle of classical thermodynamics, namely that the thermodynamic state of a simple compressible system can be uniquely determined by specifying two independent properties. We show that for certain combinations of properties, one is not guaranteed to arrive at a unique state. This caveat to the state principle is illustrated with three examples, two involving liquid water and a third using real gases. Finally, we show that to guarantee a unique state for a simple compressible system, the required two independent properties must be chosen from the trio consisting of a thermodynamic potential and its two natural variables.

Investigation of the mild surge in an axial–centrifugal compressor

The performance and structural integrity of compressors are critically impacted by aerodynamic instability. This study examines an unstable phenomenon, known as high-frequency mild surge (HFMS), in axial–centrifugal compressors through an experimental investigation and a low-order model. The results reveal that the pressure signal during HFMS is synchronized along the circumferential and streamwise directions. To elucidate the HFMS mechanism and further explore its influential law, a multi-actuator model is developed, successfully capturing the dynamic instability behavior. As the mass flow decreases, the front axial stage becomes unstable first, while the latter centrifugal stage remains stable with a negative slope near the operating point on the performance curve. The strong pressurization of the centrifugal stage maintains the stability of the entire compression system, increasing the mass flow rate. Subsequently, the pressure ratio of the latter centrifugal stage decreases with increasing mass flow, causing the front axial stage to become unstable again. The axial stage's Helmholtz frequency is consistent with the test HFMS frequency, further proving that it is a local systematic instability dominated by the axial stage. This matching feature is particularly common in combined compressors, making HFMS a typical instability phenomenon in such systems.