Compressed Gas
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Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5917
Muhammad Aziz

Decarbonization plays an important role in future energy systems for reducing greenhouse gas emissions and establishing a zero-carbon society. Hydrogen is believed to be a promising secondary energy source (energy carrier) that can be converted, stored, and utilized efficiently, leading to a broad range of possibilities for future applications. Moreover, hydrogen and electricity are mutually converted, creating high energy security and broad economic opportunities toward high energy resilience. Hydrogen can be stored in various forms, including compressed gas, liquid hydrogen, hydrides, adsorbed hydrogen, and reformed fuels. Among these, liquid hydrogen has advantages, including high gravimetric and volumetric hydrogen densities and hydrogen purity. However, liquid hydrogen is garnering increasing attention owing to the demand for long storage periods, long transportation distances, and economic performance. This paper reviews the characteristics of liquid hydrogen, liquefaction technology, storage and transportation methods, and safety standards to handle liquid hydrogen. The main challenges in utilizing liquid hydrogen are its extremely low temperature and ortho- to para-hydrogen conversion. These two characteristics have led to the urgent development of hydrogen liquefaction, storage, and transportation. In addition, safety standards for handling liquid hydrogen must be updated regularly, especially to facilitate massive and large-scale hydrogen liquefaction, storage, and transportation.

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2300
Salah Almurtaji ◽  
Naser Ali ◽  
Joao A. Teixeira ◽  
Abdulmajid Addali

Coolants play a major role in the performance of heat exchanging systems. In a marine gas turbine engine, an intercooler is used to reduce the compressed gas temperature between the compressor stages. The thermophysical properties of the coolant running within the intercooler directly influence the level of enhancement in the performance of the unit. Therefore, employing working fluids of exceptional thermal properties is beneficial for improving performance in such applications, compared to conventional fluids. This paper investigates the effect of utilizing nanofluids for enhancing the performance of a marine gas turbine intercooler. Multi-walled carbon nanotubes (MWCNTs)-water with nanofluids at 0.01–0.10 vol % concentration were produced using a two-step controlled-temperature approach ranging from 10 °C to 50 °C. Next, the thermophysical properties of the as-prepared suspensions, such as density, thermal conductivity, specific heat capacity, and viscosity, were characterized. The intercooler performance was then determined by employing the measured data of the MWCNTs-based nanofluids thermophysical properties in theoretical formulae. This includes determining the intercooler effectiveness, heat transfer rate, gas outlet temperature, coolant outlet temperature, and pumping power. Finally, a comparison between a copper-based nanofluid from the literature with the as-prepared MWCNTs-based nanofluid was performed to determine the influence of each of these suspensions on the intercooler performance.

V.E. Shcherba ◽  
A.S. Tegzhanov ◽  
D.V. Orekh

The paper analyzes the existing design schemes of hybrid power machines with a coolant moving in the jacket space due to the vacuum at the suction and introduces a new design of a single-stage single-cylinder piston hybrid power machine with two suction valves, in which the forced movement of the coolant in the forward direction is provided due to the vacuum at the suction, and in the reverse direction due to the pressure drop of the compressed gas. The analysis of the reverse expansion process allowed us to determine the value of the reduced dead space, which directly affects the volumetric feed rate of the reciprocating compressor and the feed rate in general. The parametric analysis made it possible to determine the influence of the main design and operating parameters on the value of the reduced dead space and accordingly on the volumetric feed rate. The results obtained can be useful in the design and research of reciprocating hybrid power machines with the forced movement of the coolant.

Parviz Enany ◽  
Oleksandr Shevchenko ◽  
Carsten Drebenstedt

AbstractThis paper presents experimental studies on the optimization of air–water flow in an airlift pump. Airlift pumps use compressed gas to verticall transport liquids and slurries. Due to the lack of theoretical equations for designing and predicting flow regimes, experimental investigations must be carried out to find the best condition to operate an airlift pump at high efficiency. We used a new air injection system and different submergence ratios to evaluate the output of a simple pump for vertical displacement of water in an underground mine. The tests were carried out in a new device with 5.64 m height and 10.2 cm circular riser pipe. Three air-jacket pipes, at different gas flows in the range of 0.002–0.09 m3/s were investigated with eight submergence ratios. It was found that with the same air flow rate, the most efficient flow of water was achieved when an air jacket with 3 mm diameter holes was used with a submergence ratio between 0.6 and 0.75. In addition, a comparison of practical results with two theoretical models proposed by other investigators showed that neither was able to accurately predict airlift performance in air–water flow mode.

2021 ◽  
pp. 1-13
Ceren Yüksel Alpaydin ◽  
Can Ozgur Colpan ◽  
Mustafa Umut Karaoglan ◽  
Senem Karahan Gülbay

Abstract Thanks to its features such as being harmless to the environment, not creating noise pollution, and reducing oil dependence, many countries have started promoting the use of fuel cell vehicles (FCVs) and making plans on enhancing their hydrogen infrastructure. One of the main challenges with the FCVs is the selection of an effective hydrogen storage unit. Compressed gas tanks are mostly used as the hydrogen storage in the FCVs produced to date. However, the high amount of energy spent on the compression process and the manufacturing cost of high-safety composite tanks are the main problems to be overcome. Among different storage alternatives, boron compounds, which can be easily hydrolyzed at ambient temperature and pressure to produce hydrogen, are promising hydrogen storage materials. In this study, a 700-bar compressed gas tank and a sodium borohydride (NaBH4)-based hydrogen storage system are compared for a passenger fuel cell vehicle in terms of the range of the vehicle. The energy storage and production system of the FCV were modeled in MATLAB Simulink® environment coupling the modeling equations of each component after finding the power requirement of the vehicle through vehicle dynamics. Then, the simulations were performed using the speed profile of the New European Drive Cycle (NEDC) and the acceleration requirements. According to the simulation results, the NaBH4-based hydrogen storage system provided a 4.42% more range than the compressed gas tank.

Vladimir Makarov ◽  

Research relevance. The high-level competitiveness of Russian oil and gas sector enterprises in the global economic space is impossible to reach without accelerating the restructuring of existing air-cooling apparatuses and developing new ones. It should be carried out with regard to modern technology introduction and advanced achievements in mining. The cost of gas cooling during its transportation via main gas pipelines in the cost structure reaches 22%. Besides, annual energy wastage on compressed gas cooling by fan installations is commensurate with the cost of the air cooling devices. It is essential to develop active means of air conditioning units control in order to improve their efficiency and aerodynamic adaptability that affect the competitiveness of oil and gas enterprises. ISSN 0536-1028 «Известия вузов. Горный журнал», № 4, 2021 99 Research aim is to develop a mathematical model for fan unit parameters active control. Research methods are based on the experimentally proven hypothesis about the dependence between the control flow rate on the impeller blades and the position of the rear critical points of the blades. Research results. A method was developed based on conformal transformations, the theory of residues, singular equations, and hydrodynamic analogy. The dependence between the position of the profiles critical points and flow circulation was obtained. The dependence of the aerodynamic adaptability of the fan units in air conditioning devices on effective critical point position and the energy characteristics of the impeller blades flow controlling source has been established. A patent was obtained for the fan unit impeller with active circulation control from air flow sources from the fan casing. High efficiency of the developed circulation control method for increasing the operational efficiency and aerodynamic adaptability of air-cooled fan units has been proved. An aerodynamic scheme of ОV 121TN was developed. A fan unit OGM VU2.7-1.8K4 with aerodynamic adaptability increased by 34% was created.

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3343
Tianyu Lin ◽  
Yongpeng Zhang ◽  
Zhijian Lu ◽  
Zhengwen Wang ◽  
Peng Wei ◽  

As a key component of a high-power microwave (HPM) system, a multi-gap gas switch (MGS) has recently developed insulation failure due to surface flashover. Although design criteria for surface insulation have been put forward, it is still not clear how the insulation in this case deteriorated under long-term repetitive microsecond pulses (RMPs). In this paper, flashover experiments under RMPs were carried out on various dielectric surfaces between parallel-plane electrodes in SF6 and air atmospheres, respectively. Based on tests of the surface insulation lifetime (SIL), an empirical formula for SIL prediction is proposed with variations of insulator work coefficient λ, which is a more suitable parameter to characterize SIL under RMPs. Due of the accumulation effect, the relationship between E/p and ptdelay varies with the pulse repetitive frequency (PRF) and SIL recovery capability decreases with an increase in PRF and surface deterioration is exacerbated during successive flashovers. It is concluded that the flashover path plays a crucial role in surface insulation performance under RMPs due to the photoemission induced by ultraviolet (UV) radiation, signifying the necessity of reducing surface paths in future designs as well as the improvement of surface insulation.

Antioxidants ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 955
Chunyu Wang ◽  
Changjuan Shao ◽  
Li Zhang ◽  
Sandra L. Siedlak ◽  
James S. Meabon ◽  

Traumatic brain injury caused by blast is associated with long-term neuropathological changes including tau phosphorylation and pathology. In this study, we aimed to determine changes in initial tau phosphorylation after exposure to a single mild blast and the potential contribution of oxidative stress response pathways. C57BL/6 mice were exposed to a single blast overpressure (BOP) generated by a compressed gas-driven shock tube that recapitulates battlefield-relevant open-field BOP, and cortical tissues were harvested at different time points up to 24 h after blast for Western blot analysis. We found that BOP caused elevated tau phosphorylation at Ser202/Thr205 detected by the AT8 antibody at 1 h post-blast followed by tau phosphorylation at additional sites (Ser262 and Ser396/Ser404 detected by PHF1 antibody) and conformational changes detected by Alz50 antibody. BOP also induced acute oxidative damage at 1 h post-blast and gradually declined overtime. Interestingly, Extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) were acutely activated in a similar temporal pattern as the rise and fall in oxidative stress after blast, with p38 showing a similar trend. However, glycogen synthase kinase-3 β (GSK3β) was inhibited at 1 h and remained inhibited for 24 h post blast. These results suggested that mitogen-activated protein kinases (MAPKs) but not GSK3β are likely involved in mediating the effects of oxidative stress on the initial increase of tau phosphorylation following a single mild blast.

Anatoly Nikolaevich Sobolenko ◽  
Maria Vasilievna Florianskaya

The article underlines the interest to using gas fuel in diesel engines of the coastal fishing vessels. If the change to liquefied natural gas is limited by the lack of bunkering capabilities in the Russian ports, using compressed gas has become widespread in transport and in the household. A number of gas fueling stations are already available for this purpose. It seems reasonable to start the conversion of the port fleet to compressed gas from using the motor gas bottling equipment for that purpose. It is important to evaluate the change in engine performance parameters when converting to compressed gas. Compressed gas is a mixture of gases such as propane, ethane, butane, methane, etc. There is given the percentage of each gas content, according to GOST. The quantitative composition of the pure compressed gas combustion outcomes, as well as the gas ignited by the ignition diesel fuel was determined by the oxidation reactions of the chemical elements of which they consist, as well as by oxygen from air. As a result of regression analysis applied to define the properties of water vapor and gases, there have been derived linear and quadratic approximating dependences of the heat capacities of gases (CO2, N2) and water vapor (H2O) on temperature. There have been obtained the equations for determining the heat capacity of the combustion products of compressed gas for fuel grade A and B. There have been produced the formulas for determining heat capacity of pure combustion products of compressed gas ignited by the ignition diesel fuel. The obtained expressions are recommended to be used for analysis of the working cycle of a diesel engine running on the compressed gas.

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