Compressed Air System Research Articles

Exergy, economic and pinch analyses of a novel integrated structure for cryogenic energy storage and freshwater production using ejector refrigeration cycle, desalination unit, and natural gas combustion plant

This study aims to investigate an innovative hybrid structure of electricity storage at off-peak hours and its application at on-peak hours. In this paper, a novel hybrid system for energy storage and freshwater production using air compression and liquefaction system, ejector refrigeration cycle (ERC), thermal multi-effect desalination (MED) system, and natural gas combustion unit (GCU) is developed. The wasted heat of the liquefaction cycle is stored at off-peak hours to provide heat to the ERC and thermal desalination system and preheat the inlet streams to the turbines at on-peak hours. Also, wasted refrigeration of liquid air stream and refrigeration resulting from liquefied natural gas (LNG) regasification operations are stored at on-peak hours and are utilized in compressed air liquefaction at off-peak hours. This integrated structure produces 83.12 kg/s liquid air and 38.91 kg/s freshwater at off-peak hours with 58.24 MW power consumption. During on-peak hours, the liquid air along with 2.681 kg/s LNG enters the turbines after preheating and combustion and generated 122.6 MW power. Round-trip and storage efficiencies are obtained as 64.91% and 75.96%, respectively. Also, the exergy efficiencies of the energy storage system at off-peak hours, energy production system at on-peak hours and the whole system are estimated as 78.13%, 75.85%, and 65.92%, respectively. The results of the exergy study illustrate the reactors (43.37%), heat exchangers (26.76%), and throttle valves (10.58%) have the highest contribution to exergy destruction in the proposed combined structure, respectively. This study provides the refrigeration cycle integration with process core as hot and cold composite curves and pinch analysis. Pinch investigation is conducted on the system multi-stream exchangers and the heat exchanger networks are extracted. The economic analysis illustrates that the investment return period, the levelized cost of the product, and net annual benefit in the hybridized system are 4.877 years, 0.0919 US$/kWh, 78.38 MMUS$/year, respectively. The results of sensitivity analysis indicate the round-trip efficiency increases up to 65.32% by raising the pressure of the on-peak power generation cycle.

Identification of energy wastes through sound analysis in compressed air systems

This paper proposes a new approach which is able to identify energy losses of compressed air in any CAS based on acoustic energy emission. By means of a previously validated mathematical model, the inverse problem that finds air power lost over time from the sound generated by air expansion is solved. The developed method is tested in a laboratory scale while a tank is being emptied through artificial holes with different diameters in a pipe. Two supplying cases: continuous supply of compressed air to the tank and single filling of the tank are considered. All measurements are made in an anechoic chamber to record pure air expansion noise without any background sounds. The analysis shows that over certain range of leakage hole diameters there is a dependence between the generated sound pressure level and the mass flow and, therefore, the power loss. Thus, acoustic monitoring could be effective in leakage diagnosing in CASs, which is important for production energy efficiency management.

An Integrated Energy Simulation Model of a Compressed Air System for Sustainable Manufacturing: A Time-Discretized Approach

A compressed air system (CAS) is one of the most common and energy-consuming systems in manufacturing. To practice more economically and environmentally sustainable manufacturing, manufacturers need ways to reduce the energy costs and carbon footprint, resulting from a CAS in their production systems. While preliminary energy studies on a CAS and on machining processes are available separately, existing research studies rarely analyze energy costs using a tool that considers both a CAS and production systems. Therefore, in this study, we propose an energy simulation tool that combines a CAS and a production system to evaluate the effects of a CAS and production parameters on energy consumption and costs at a factory level. In particular, we develop a time-discretized algorithm for simulating a CAS to accurately consider the dynamics of CAS parameters such as pressure and flow rate. From 48 simulation case studies, we show that changes in a CAS such as proper HP sizing, a reduction in compressed air leaks, and a decrease in the discharge pressure can increase productivity and reduce energy costs by up to 11%. The simulation analysis from this study suggests a way to help manufacturers and researchers find more sustainable ways to achieve energy-efficient configurations for production systems including a CAS.

Alumina and low density polyethylene composite for ballistics applications

The efficiency of alumina and low-density polyethylene (LDPE) composites in ballistic applications was investigated. Different concentrations of alumina were studied, 70, 75, 80, 85, 90 wt.%. The ballistic tests were carried out at subsonic speed using a compressed air system and projectile 0.22. In addition, Charpy impact tests were conducted for mechanical characterization; optical microscope images were used to evaluate the projectile after the ballistic tests; fractography studies were conducted with scanning electron microscope equipped with x-ray energy dispersive spectroscopy detector; density was measured by Archimedes experiment. The results demonstrate that the proposed composites have a good performance in ballistic applications, showing themselves to be a viable alternative. The composite with 80 wt.% alumina and 20 wt.% LDPE showed the best performance.

Trading One Risk for Another: Consequences of the Unauthenticated Treatment and Prevention of Silicosis in Ontario Miners in the McIntyre Powder Aluminum Inhalation Program.

From 1943 to 1979, miners and factory workers in more than two hundred work sites globally were subjected to mandatory medical treatments by their employers as an unproven, and ultimately ineffective, treatment to prevent the lung disease silicosis. The treatments involved inhaling finely ground aluminum dust known as McIntyre Powder, blown into miners’ change rooms each shift using compressed air systems. Tens of thousands of industrial laborers were exposed to McIntyre Powder, yet their story is scarcely known, and the possible health impacts of their aluminum treatments were rarely studied. This paper integrates the history of the aluminum prophylaxis program and its control by the northern Ontario mining industry with the lived experience of one of the affected miners, whose daughter created a voluntary registry which documents health issues in exposed miners, and stimulated research that found a link to her father’s Parkinson disease.

Energy, Exergy, and Emission Analysis on Industrial Air Compressors

Abstract Air compressors, a key fluid power technology, play an essential role in industrial plants and office buildings, hospitals, and other types of facilities. The efficient use of the air compressor is crucial. By controlling unnecessary inefficiencies, high energy consumption can be reduced. This study aims to provide energy and exergy analysis on air compressors for different industries. Detailed case studies were also analyzed. The case study focuses on the energy and exergy analyses of the compressed air system of foundry industries. The results indicate that applying the six improvement recommendations yields significant amounts of energy and cost savings and significant improvements in the system's overall performance. The payback periods for different recommendations are economically feasible and worthwhile to use. The suggested improvement methods can provide cost savings with a low payback period.

Working Principle and Design of PLC Air Compressor System

Working Principle and Design of PLC Air Compressor System

Mathematical Modelling of a System for Solar PV Efficiency Improvement Using Compressed Air for Panel Cleaning and Cooling

The efficiency of solar photovoltaic (PV) panels is greatly reduced by panel soiling and high temperatures. A mechanism for eliminating both of these sources of inefficiencies is presented by integrating solar PV generation with a compressed air system. High-pressure air can be stored and used to blow over the surface of PV panels, removing present dust and cooling the panels, increasing output power. A full-system mathematical model of the proposed system is presented, comprised of compressed air generation and storage, panel temperature, panel cleaning, and PV power generation. Simulation results indicate the benefit of employing compressed air for cleaning and cooling solar PV panels. For a fixed volume of compressed air, it is advantageous to blow air over the panels early in the day if the panel is soiled or when solar radiation is most abundant with the highest achievable flow rate if the panel is clean. These strategies have been shown to achieve the greatest energy captures for a single PV panel. When comparing the energy for air compression to the energy gain from cleaning a single PV over a two-week period, an energy ROI of 23.8 is determined. The system has the potential to eliminate the requirement for additional manual cleaning of solar PV panels.

Electrothermal Desiccant Regeneration Technique for Air Dehumidification

Adsorption dehumidification and drying equipment is essential general equipment for domestic and industrial use. The most commonly used type in industry is the compressed air adsorption dryer. The analysis results show that the heat loss of the traditional heat air regeneration system of the compressor dryer is 39.4%, and the exhaust waste heat is 32.4%. The actual use of heat energy for desiccant regeneration is only 28.2%. Therefore, this study uses an innovative electrothermal adsorbent unit (ETAU) to regenerate the desiccant. By directly heating the adsorbent, heat loss can be effectively improved. On the other hand, the composite arrangement of zeolite and activated alumina is used. The inlet compressed air is firstly treated by the activated alumina, which has a high adsorption capacity in the high relative humidity condition, then a zeolite is used as a second part to make the dew point reach –40 °C. In the regeneration step, the airflow direction is reversed, whereby the zeolite is regenerated by the ETAU, and the waste heat of the exhaust air is used to regenerate the activated alumina, which reduces the temperature of the exhaust air. Compared with the traditional heat air compressed air system, the two technologies can save about 27% energy in total.

Effect of cross-head speed and temperature on the mechanical properties of polypropylene and glass fiber reinforced polypropylene pipes

Recently, glass fiber reinforced polypropylene is commonly used in scientific and industrial applications such as marine, aerospace, automotive, and construction industries among other materials because of their low cost, lightweight, easy processing, and high reliability. For those promising characteristics, researches have been undertaken for understanding the thermal and mechanical behaviors of polypropylene. The main objective of this study is to investigate the mechanical properties of polypropylene (PP) and glass fiber reinforced polypropylene (GFPP) pipes, which are used in water distribution networks and compressed air systems. Tensile tests were performed at different cross-head speeds at room temperature while, flexural tests were conducted at different cross-head speeds with five distinct temperatures 23, 35, 50, 70, and 90 °C. The experimental results show that both materials are sensitive to cross-head speed, temperature, and holding time. Additionally, the percentage of elongation at break and toughness of GFPP are lower than that of PP. However, the elastic modulus and yield stress of GFPP are higher than that of PP at the same cross-head speed. On the other hand, the bending energy and the dissipated energy of GFPP are higher than that of PP under all cross-head speeds and testing temperatures. PP gains 20.4% and GFPP gains 15.2% bending energy with raising cross-head speed from 5 to 50 mm/min. Also, a decrease in flexural modulus for both materials occurs with raising temperature from 23 to 50 °C.

Energy savings in compressed air systems a case of study

The compressed air applications are highly used in the industrial sector due to its easy transportation, safety, purity, cleanliness and storage capacity. In many regions, compressed air system accounts for about 10% of the industrial electricity energy bill. However, compressed air is expensive because around 30% of the consumed energy is used for these systems in an industrial facility. Energy used to be lost as leaks, pressure drops, heat, misuse, among others. Several energy efficiencies measures help to improve energy savings in companies such as: pressure reduction, reduce the inlet air temperature, use a well-calculated capacity tank for storage, control heat recovery and reduce leaks, giving potential energy savings in a range between the 20% to 60%, with a return of investment not higher than two years. As result, this document analyzes the energy efficiency measures that can be considered for compressed air systems applications, calculates the energy saving potentials, and assesses a case of study in a company in the city of Barranquilla.

Universal Programmable Portable Measurement Device for Diagnostics and Monitoring of Industrial Fluid Power Systems.

This paper presents a new universal programmable portable measuring device (PMD) as a complete, accurate, and efficient solution for monitoring and technical diagnostics of industrial fluid power systems. PMD has programmable functions designed for recording, processing, and graphical visualization of measurement results at the test stand or the place of operation of fluid power systems. PMD has a built-in WiFi communication module for transferring measurement data via Industrial Internet of Things (IIoT) technology for online remote monitoring of fluid power systems. PMD can be programmed for a variety of measuring tasks in servicing, repairing, diagnosing, and monitoring fluid power systems. For this purpose, the fluid dynamic quantity, mechanical quantity, and electrical quantity can be measured. The adjustment of the PMD to the indirect measurement of leakage flow rate in a compressed air system (CAS) is presented in detail. Measuring instruments and PMDs were connected to a branch of the pipeline. The tests used the measurement system to estimate the leakage flow rate through air small nozzles, as well as other CAS indicators.

Comments: Growth in Battery Storage Sparks Chase for Metals

Natural gas is considered the fossil fuel to facilitate the transition from hydrocarbons to lower-emissions energy sources such as renewables. Wind and solar projects factor significantly into major international oil and gas companies’ goals of achieving net-zero emissions in the future. For example, both BP and Royal Dutch Shell intend to reach net zero by 2050. The International Energy Agency (IEA) forecasts total installed wind and solar PV capacity is on course to surpass natural gas in 2023 and coal in 2024. This represents progress toward the achievement of the 2050 goals. However, wind, solar, and hydropower, which together account for about 90% of all renewable-electricity generation, are largely dependent on variable weather conditions. And the variability in weather translates to an undesired variability in availability and reliability. For wider adoption, utility-scale batteries are needed to store energy for use when a light breeze barely whispers, or the skies are cloudy. Battery-storage projects are not a new concept, but their recent growth is notable. Although California is the global leader in the deployment of high-capacity batteries, news from other parts of the world offers indicators of progress. In 2020, global installed energy-storage capacity totaled 173.6 GW, including pumped-hydroelectric, compressed-air, advanced battery-energy, flywheel-energy, thermal-energy, and hydrogen-energy storage systems. The US had 0.74 GW of rated-power battery-storage projects based on lead-acid, lithium-ion, nickel-based, and sodium-based batteries. A Tesla subsidiary, Gambit Energy Storage LLC, is currently constructing a 100-MW+ battery-storage facility in Angleton, Texas, about 40 miles south of Houston. It is expected to become operational 1 June. Elon Musk (best known for his Tesla electric vehicles and SpaceX) launched a 100-MW lithium-ion battery project in South Australia in 2017 adjacent to a wind farm. Soon to become a “hot(ter)” commodity will be the lithium, rare earths, and other minerals needed to build the batteries. The global lithium and cobalt markets rallied in January and February in response to the resurgence of demand for electric vehicles (EV) in Europe. Last year, sales in battery EVs and plug-in-hybrid EVs in Europe outpaced those in China. Adamas Intelligence reported that the second half of 2020 saw a global 205% increase in battery cobalt deployed, a 192% increase in battery lithium deployed, and a 135% increase in battery nickel deployed vs. the second half of 2019. Investors and companies are chasing this potentially lucrative sector. Startup DeepGreen Metals, whose partners include Maersk and Allseas, aims to mine the deep sea for battery metals and on 4 March announced an agreement to merge with Sustainable Opportunities Acquisition Corp. to list on the Nasdaq. Cornish Lithium, holding rights to explore for lithium within geothermal waters in areas off the north and south coasts of Cornwall, UK, recently signed on MarineSpace to help it begin its desk-based exploration program to identify potential geological targets for later research. Physical exploration work is not expected for at least 4 years.

Thermodynamic analysis of an organic Rankine–vapor compression cycle (ORVC) assisted air compression system for cryogenic air separation units

Air compression is the main energy consumption process in cryogenic air separation units (ASUs), while compression waste heat occupies over 60% of the total compression power. However, the compression waste heat has not yet been recovered in existing ASUs, implying a great potential for energy efficiency improvement. In this paper, an organic Rankine-vapor compression cycle (ORVC) assisted three-stage air compression system (ORVC-ACS) is proposed. The compression waste heat is recovered by the ORVC to generate cooling capacity to precool the inlet air of the air compressors, which thus reduces its compression power consumption. Humidity constraint is specially considered in the thermodynamic model as the heat source is pressurized humid air. The feed air conditions (i.e., temperature and humidity) and operation parameters (i.e., the compressed air temperatures, evaporation temperatures and condensation temperature) are first investigated and optimized to study their effects on system performance. The operating ranges of the feed air and operation parameters are further analyzed and identified to ensure no condensed water during the air compressor operation. The optimization results show that the maximum energy saving ratio (ESR) of the ORVC-ACS reaches 4.2%, corresponding to a total annual energy saving of 7500 MWh for a 60,000-Nm3/h scale ASUs. It is found that the proposed ORVC-ACS is able to work under the feed air temperature range of 5.35–22.5 °C and relative humidity range of 0–0.8. In addition, economic and environmental assessment shows that a discounted pay-back period of 3.1 years and annual carbon-dioxide emission reduction of 5400 t are attainable with the proposed ORVC-ACS, indicating that it is economic viable with excellent decarbonization potential. This work would provide guidance for practical compression system operation in cryogenic ASUs.

Improved Modeling of a Multi-Level Inverter for TACS to Reduce Computational Time and Improve Accuracy

A modeling of a turbo air compressor system (TACS), with a multi-level inverter for driving variable speed, combining an electrical model of an electric motor drive system (EMDS) and a mechanical model of a turbo air compressor, is essential to accurately analyze dynamics characteristics. Compared to the mechanical model, the electrical model has a short sampling time due to the high frequency switching operation of the numerous power semiconductors inside the multi-level inverter. This causes the problem of increased computational time for dynamic characteristics analysis of TACS. To solve this problem, the conventional model of the multi-level inverter has been proposed to simplify the switching operation of the power semiconductors, however it has low accuracy because it does not consider pulse width modulation (PWM) operation. Therefore, this paper proposes an improved modeling of the multi-level inverter for TACS to reduce computational time and improve the accuracy of electrical and mechanical responses. In order to verify the reduced computational time of the proposed model, the conventional model using the simplified model is compared and analyzed using an electronic circuit simulation software PSIM. Then, the improved accuracy of the proposed model is verified by comparison with the experimental results.

Numerical investigation of thermal deformation of meshing pairs in single screw compressor

Single screw compressor serves as a core component in air compression system, mechanical vapor recompression system, low-temperature heat pump system and so on. However, under high temperature conditions, thermal deformation will lead to misaligned meshing between the vertical meshing pairs of the screw rotor and the star wheels. It would also lead to the serious abrasion of the components. Thus, it is necessary to investigate the thermal deformation mechanism of the single screw compressor to provide a guiding for clearance setting and strategy of assembling. In this paper, the thermal deformation mechanism of the meshing pairs in SSC is analyzed by using finite-element methods under the actual thermal boundary conditions tested by the infrared temperature camera. The results point out the deformation laws of the meshing pairs and torsional deformation of the screw rotor which cause the misaligned engagement. Influence of the thermal deformation on most of the clearances could be eliminated or controlled by setting reserved clearances. Such as the misaligned meshing could be controlled by reserving an axial assembling clearance and adjusting the bearing position. However, the torsional deformation of the screw rotor could only be modified by compensation machining. The method and results in this paper can be adopted for designing the meshing pairs and setting the design clearance of the compressor.

Performance analysis of a novel hybrid solar photovoltaic - pumped-hydro and compressed-air storage system in different climatic zones

It has been proven that the future of energy demands for human society is related to renewable energy sources such as solar energy. However, the operation of solar energy systems is associated with some challenges, such as naturally uncertainty, instability, and intermittently at different hours of the day, which has caused problems with their widespread use. One of the most innovative ways to overcome these challenges is to use energy storage systems. The Pumped-Hydro and Compressed-Air (PHCA) system is a new energy storage system which can be coupled with power generation from renewable energy sources such as wind and solar. The aim of the present study is to evaluate the performance of the PHCA system is coupled with power generation from photovoltaic (PV) system from the energy and exergy points of view. The proposed energy system is able to generate electricity and storing energy. The solar PV system absorbs solar energy and converts it to the electricity. This electrical energy is then fed to the pump of storage system. Then, the required energy is produced by the turbine of storage system when needed. To examine the energy system performance, two different scenarios are considered: the first determines the required number of solar PV panels for a constant capacity of the PHCA storage system. In the latter, the storage system volume is determined for a solar PV system with a capacity of 1 kW. To evaluate the energy system performance the climatic conditions of two different cities in the Middle East (Dubai and Yazd) are considered. The results of the scenario I revealed that, the required pump work, which must be supplied by solar PV system, is equal to 3.69 and 4.0 MJ/m3 for isentropic and isothermal processes, respectively. In such a context, the total efficiency of the energy system is equal to 63.75%. In addition, the total exergy destruction of energy system for isentropic process is 8.36% and 8.39% less than that isothermal process in Dubai and Yazd, respectively. From scenario II, it was fond that the storage system should have a fixed capacity of 7.79 and 7.19 m3 for isentropic and isothermal processes, respectively. Based on research findings engineers must establish the right balance between the storage system and the solar system according to the energy needs for storage, storage volume, storing water method, and hours of operating and geological requirements.

Big data analytics energy-saving strategies for air compressors in the semiconductor industry – an empirical study

Industry 4.0, smart manufacturing and its related technologies are now becoming the leading trend in the development of the manufacturing industry. One of the key drivers of Industry 4.0 is big data analytics, which can transform large amounts of data into useful information, enabling astute and rapid decision-making strategies when combined with expert domain knowledge. The semiconductor industry is the most important high-tech industry in Taiwan, but it is also one of the most energy-consuming industries in the country. Therefore, it is critical to improve the efficiency of the manufacturing process and reduce the overall energy consumption of facility systems. This research demonstrates how to apply big data analytics in the semiconductor industry to explore the relationships of various machine parameters, develop predictive models for machine energy efficiency and apply optimisation tools to minimise energy consumption, while meeting the production demands. An empirical study is conducted in conjunction with a semiconductor corporation in Taiwan, targeting the air compressor system in its factory. The research framework is shown to be capable of assisting semiconductor fabrication plant decision-makers in optimising machine configurations, resulting in more than 10% savings on energy consumption and significantly decreased manufacturing costs.

Sizing and operation of energy storage by Power-to-Gas and Underwater Compressed Air systems applied to offshore wind power generation

Among the possible solutions for large-scale renewable energy storage, Power-to-Gas (P2G) and Compressed Air Energy Storage (CAES) appear very promising. In this work, P2G and an innovative type of CAES based on underwater storage volumes (UW-CAES) are compared from a techno-economic point of view, when applied in combination with a 48 MWe offshore wind power plant, selecting an appropriate location for both high productivity and favorable seabed depth. An optimization model is employed to study the system design and operation, maximizing the lifetime plant profitability, while considering differential installation and operation costs, market values of the products (i.e., hydrogen and electricity), and technological constraints. In the current economic and technological scenario, the resulting P2G system has a nominal power equivalent to about 10% of the wind park capacity, with a small hydrogen storage buffer. On the other hand, the compressor and the turbine of the UWCAES have a nominal power close to the full wind farm capacity, and large underwater compressed air tanks are required. Both options significantly impact the wind plant management but the most beneficial applications of the two systems are different: the P2G results in a compact and flexible unit, whereas the UW-CAES is able to exploit a higher average conversion efficiency (about 80% round-trip) against a much higher installed power and investment cost. Anyway, considering the current framework, the resulting economics are still inadequate, but their competitiveness can improve compatible with the expected evolution of energy markets in the next future.

Study of Master Controller Structure for Multiple Air Compressor System

Compressed air is an important medium for energy transfer in industrial processes. It drives various actuators, which create a large force for significant movements and a high operation speed. Thereat, these mechanisms are quite small, and the design is simple and reliable. They are applicable in food and pharmaceutical technologies. Compressed air systems belong to the largest energy consumers at such enterprises. They consist of several compressors, and the drive of one of them is powered by a frequency converter in order to save electrical energy. This is called a multiple air compressor system, and its operation is controlled by a separate controller – master controller. The paper discusses the results of developing the master controller design and its operation algorithm. As an additional informative signal in the developed design of the master controller, air flow rate measurements are used; additionally, the speed of the air flow rate variation is analysed.