Low-pressure Tank Research Articles

Simulation study on preventing explosive mixture formation in PEM electrolysers’ water recovery tanks

Investigations of safety issues related to the design and operation of high-pressure proton exchange membrane (PEM) water electrolysers have until now mainly focused on the electrolyser stack. The present study focuses on the risk of explosive mixture formation in the water recovery system, which is part of the balance of plant in water electrolysers. After a major electrolyser company experienced an unexpected detonation in their system, we analysed their process design as a base case: a low-pressure buffer tank where anodic and cathodic water is mixed with make-up deionised water poses a safety risk because an explosive gas mixture is likely to form there, resulting in severe accidents. Several retrofit options are explored using dynamic and steady-state simulation models: these options are then evaluated based on their effects on safety, general economics and operation of the plant, in addition to ease of retrofit. The results show that preventing the formation of explosive gas mixtures in the water recovery system is achievable in several ways, such as avoiding recycling cathodic water altogether, stripping it of hydrogen, flushing buffer tanks with nitrogen or oxygen, rearranging the balance of plant appropriately, or changing the control algorithms of the system.

Energy, exergy, economic, and environmental analyses and optimization of a multigeneration system considering high-temperature island environment

Renewable energy based multigeneration systems help satisfy the diverse demand for marine resources exploration in off-grid island area, where the storage of fluctuating renewable energy for continuous power supply becomes necessary. Therefore, this paper proposes a solar-driven multigeneration system for island environment integrated with energy storage and production of electricity, cooling, heating, and freshwater. The system comprises an ejector power subsystem, a multiple-effect distillation subsystem, and a CO2 binary mixture-based compressed gas energy storage subsystem. The system performance from the perspectives of energy, exergy, economics, and environment, as well as the impact on performance of the working fluid and several key system parameters, are investigated in this paper. According to the results, an increase in the mass fraction of organic in the CO2 mixture leads to an improvement in system energy efficiency and exergy density at the cost of lower system power efficiency. Increasing the high-pressure tank pressure enhances system performance except for system power efficiency. Increased low-pressure tank pressure leads to improved system energy efficiency and exergy density, accompanied by lower system power efficiency and exergy efficiency. When the ambient temperature increases from 298 K to 303 K, the system energy efficiency noticeably decreases, whereas an increase in direct normal irradiance improves various system performance indicators. Among several mixtures, CO2/R32 mixture was chosen for further analysis and optimization for its wider operating range with R32 mass fraction and better system performance. The optimal operating point had system energy efficiency, exergy density, and modified levelized cost of energy of 1.281, 22.216 kWh/m3, and 0.131 $/kWh, respectively. The proposed system in this research is proven to be a novel technical solution to meet the diverse energy demands on unique island environments.

Multi-objective optimal sizing and design of renewable and diesel-based autonomous microgrids with hydrogen storage considering economic, environmental, and social uncertainties

The multifaceted nature of human society necessitates the consideration of various indicators when planning and designing energy systems. The success of energy systems is contingent on their ability to reliably meet demands while satisfying different objectives that align with societal needs. This paper presents the multi-objective optimal design and configuration of hydrogen-storage-based microgrids to reliably meet electric load demands in remote regions while considering economic, environmental and social uncertainties. A comprehensive Mixed Integer Linear Programming (MILP) was adopted to model the microgrid consisting of renewable energy systems (RES), hydrogen energy storage system (HESS), battery energy storage system (BESS), and diesel generator (DG). Advanced Interactive Multidimensional Modelling System (AIMMS) was used to perform the deterministic and robust optimisation with special consideration on cost-greenhouse emissions minisation and employment generation maximisation. This study further performs a comparative analysis between hydrogen-based microgrids and lithium-ion battery-based microgrids in terms of the key objectives. In overall performance, the configuration consisting of photovoltaic (PV), wind turbine (WT), fuel cell (FC), electrolyser (EL) and low-pressure tank (LPT) outplays the other configurations considered in terms of total job factor, levelised cost of electricity, renewable energy penetration factor, carbon emission reduction capability. Considering both deterministic and robust solutions of the configuration, the levelised cost of electricity ranges between 0.131 and 0.169 $/kWh, the total lifetime cost varies from $2,002,100 to $6,784,740, and the job provision factor ranges between 0.339 and 0.447. Nevertheless, there is a need for further reduction of the investment cost for its continued technological and market penetration. This is a good basis for the adoption of hydrogen-based storage systems with renewable energy systems.

New type of cavitation instability with peculiar frequency characteristic in liquid rocket inducer

In a liquid rocket turbopump with low pressure and thin wall tanks, cavitation inevitably occurs at the inducer which is installed at the inlet of the turbopump. The cavities at each blade oscillate periodically, and the turbopump sometimes becomes unstable, called cavitation instability. Rotating cavitation is one of the common types of cavitation instability, in which the cavities at each inducer blade oscillate respectively and appear to propagate from blade to blade. However, the new type of cavitation instability which does not follow the conventional principle has been observed in our experiment with an inducer. Converting the frequency in the inertial frame to that in the rotational frame and organizing it in the cavitation number, it was found that the frequency of unsteady cavitation increases as the cavitation number decreases, and this is the peculiar point of this instability. Additionally, during the cavitation instability, a few numbers of backflow vortex cavities were observed and moved sub-synchronously from blade to blade. In addition, the tip leakage vortex cavitation on each blade also propagates like sub-synchronous rotating cavitation but in different propagation speed from that of the backflow vortex cavities. As a result, it was supposed that the new instability is one of the types of sub-synchronous rotating cavitation related to backflow vortex cavitation, tip leakage vortex cavitation, and interaction between cavity propagation and inducer blade.

Design of low-pressure transportable steel tanks for storing hydrogen for an electric tractor

The presented contribution offers a theoretical analysis of the possibilities of implementing hydrogen technologies in agricultural machines and tractors. It discusses in more detail the structural designs and strength calculations of low-pressure transportable steel tanks for hydrogen storage for the ET 3000 electric tractor, in which the accumulators will be replaced by designed metal hydride tanks. The structural design of low-pressure tanks meets the requirements of the STN EN 13322-2 standard, which deals with the technical and structural design of transportable pressure tanks. The design and construction of tanks are key from the point of view of the real implementation of hydrogen technology in a fully functional small tractor for the purpose of its long-term testing.

Thin-walled tapered conformable low-pressure tanks: Concept and principles

In pressure tank design, structural efficiency or the ratio of pressurized volume to structural mass is fundamental and implies a specific shape, such as a cylindrical or spherical layout. However, this axi-symmetric layout may be not conform to the enveloping shape. Previous investigations developed a conformable tank concept with a multi-bubble axi-symmetric layout, called a multi-lobe, multi-cell or multi-bubble tank, but structural design and analysis are limited to intersecting cylindrical, spherical or toroidal shells. The objective of this research is to increase the volumetric efficiency of multi-bubble tanks even further through the introduction of a conical shell. An integral analytical formulation of tank topology and explicit expression of equilibrium are provided in order to design a structurally efficient tapered multi-bubble tank under low differential pressure. The result is expressed in a geometric rule that is applicable for tapered multi-bubble tanks of any eligible shape.

Emission spectroscopy diagnosis and discharge characteristics distribution analysis of high-frequency, high-enthalpy inductive coupling plasma generator

To study the electromagnetic properties through reentry plasma on ground, a large-sized inductive coupled plasma generator is designed to produce a long-duration, large size and high temperature plasma flow in a low-pressure vacuum tank. Among all plasma parameters, the spatial distribution of electron density and electron temperature is of utmost importance for analyzing the electromagnetic scattering properties. In this study, we used the emission spectroscopy diagnosis method to explore the aforementioned parameters at two locations: upflow and downflow of the discharge coil in the plasma generator. Experiments were conducted under various discharge conditions for argon, with the panel power ranging from 28 kW to 85 kW. The results showed that, at the upflow of the discharge coil, the electron temperature at the center was higher than that at the edge, exhibiting an arch-shaped profile. However, at the downflow of the discharge coil, the electron temperature at the center was lower than that at the edge, exhibiting a saddle-shaped profile. The electron density exhibited a completely opposite distribution compared to the electron temperature, with higher values at the edge for upflow and higher values at the center for downflow. By varying the panel power, we observed the similar phenomenon: the electron temperature decreased, while the electron density increased with the increase in power. Finally, brief analysis was provided at the end of the paper. This study offered valuable insights into the transition of plasma distribution in a plasma generator, providing a reference for future research on the propagation of electromagnetic waves in plasma sheaths.

Stem Cells from Human Exfoliated Deciduous Teeth Alleviate High-Altitude Cerebral Oedema by Shifting Microglial M1/M2 Polarisation.

To explore the high-efficiency and low-risk prevention and treatment strategies for stem cells from human exfoliated deciduous teeth (SHED) for high-altitude cerebral oedema. A low-pressure and low-oxygen tank mimicking high-altitude conditions was used to establish the high-altitude cerebral oedema animal model. The preventive effects of SHED for cerebral oedema were then evaluated by haematoxylin and eosin (H&E) and histological staining. In vitro, SHED was co-cultured with BV-2 to analyse the effects of SHED by western blot and immunofluorescence staining. SHED can prevent and treat cerebral oedema in a high altitude rat animal model. Mechanistically, SHED treatment can protect brain cells from apoptosis induced by high altitude condition. Moreover, SHED treatment can inhibit M1-type polarisation and promote M2-type polarisation of microglia cells via the suppression of hypoxia inducible factor (HIF)- 1α-mediated extracellular signal-regulated kinase (ERK) signalling activated in high altitude condition. SHED treatment can relieve high-altitude cerebral oedema via inhibiting HIF- 1α-mediated ERK signalling, which indicates that SHED is a promising alternative strategy to prevent and treat high-altitude cerebral oedema.

Bubble dynamics in a pressure gradient with reentrant jet break through and energy loss

The dynamics of a bubble in a pressure gradient is investigated experimentally and numerically with particular emphasis on the behavior at reentrant jet impact and break through the opposite side of the bubble with corresponding energy loss and vorticity generation. High speed photography observations of a bubble generated by electric spark energy deposit in a low ambient pressure tank are coupled with wavelet based Optical Flow Velocimetry (wOFV) and Boundary Element Method (BEM) numerical analysis to examine the flow field resulting from the reentrant jet formation and break through. We study, as an illustration, the effects of the constant pressure gradient due to gravity on the bubble dynamics. Energy losses between the first and second cycle are measured for the bubbles generated under various conditions characterized by a non-dimensional pressure gradient parameter, and the corresponding measured energy loss is used in the numerical simulations. Good correspondence is seen between the image analysis, the wOFV computations, and the BEM results and insight is gained on the involved physics.

Correlation analysis of injection parameters for low-medium pressure injection of liquid CO2 for CH4 displacement in coal seams

The injection parameters for liquid CO2 to displace CH4 in a coal seam depend on engineering analogy and construction experience. To explore the relationship between key pressure injection parameters, such as liquid injection pressure and liquid injection volume, a combination of theoretical analysis and a downhole pilot test was used. The effective displacement radii of the CO2 and CH4 extraction under different liquid injection pressures were compared. The correlations between the volume, flow, time, and pressure of the injection liquid were analyzed. The results showed that the influence radius of CO2 effective displacement and influence period of CO2 pressure injection were proportional to the injection pressure. Low-pressure tank injection effectively promoted the extraction of coal seam CH4, whereas medium-pressure pump injection greatly enhanced the extraction of CH4. Therefore, in a low-to-medium pressure injection range, the higher the injection pressure of the liquid CO2, the better the displacement effect. A correlation analysis of the liquid injection parameters reveals that the liquid injection volume shows a concave nonlinear increasing trend with an increase in the liquid injection pressure, the liquid injection flow shows a parabolic trend of the upper opening with the increase of the liquid injection pressureand the liquid injection time shows a parabolic trend of the lower opening with an increase in liquid injection pressure. A comprehensive analysis shows that the optimal injection pressure and volume for the low-medium pressure injection of liquid CO2 to displace coal seam CH4 are 7.5 MPa and 7.4 m3, respectively.

Ultra-microporous biochar-based carbon adsorbents by a facile chemical activation strategy for high-performance CO2 adsorption

The new adsorption-enhanced compressed CO2 energy storage technology uses high-performance adsorbents to adsorb and store CO2 in low-pressure tanks, reducing vessel costs while significantly increasing energy storage density. In this paper, porous biochar with excellent CO2 adsorption capacity is prepared by carbonization combined with KOH chemical activation using pine nut shells, which can be used for the energy storage system. The influence of pore structure is revealed by changing the activation temperature. The results show that the activity of KOH is moderate at 700 °C, which can promote the formation of ultramicropores. The specific surface area of the obtained porous biochar is 1027 m2·g−1, the distribution center of ultramicropores is about 0.65 nm, and the microporosity can up to 91.7%, which is very suitable for CO2 adsorption under atmospheric pressure and room temperature. The CO2 adsorption capacities are 6.05 mmol·g−1 and 3.96 mmol·g−1 at 1 bar, 273 K and 298 K with the pore volume is only 0.56 cm3·g−1. The material also has a low value of isosteric heat of adsorption about 25 kJ·mol−1. These findings suggest that pine nut shells can be used to design highly porous biochar for the system of new adsorption-enhanced compressed CO2 energy storage.

Study on the effect of Xiaoqinglong decoction on vascular endothelin inpulmonary hypertension rat based on Jiebiaokuoluo method

To discuss the effect of Xiaoqinglong decoction on vascular endothelin (ET) in rats pulmonary hypertension (PAH) model based on the Jiebiaokuoluo method. Sixty male SD rats were randomly divided into six groups: control group, PAH model group, positive drug group, and Xiaoqinglong decoction in the high-dose, medium-dose and low-dose groups, 10 rats in each group. The control group did not receive any treatment. The remaining groups were kept in low-pressure oxygen tanks, injections of lipopolysaccharide (LPS) at 200 μL on day 1 and day 14, respectively. The rats were smoked twice a day from day 2 to day 30 (except day 14) at 4 hours intervals. The rats were placed in a low-temperature environment for 1 hour per day, and were put into cold water to swim (for 2 weeks), while the rats were given a cold diet. After modeling, the control group and the PAH model group were given equal volumes of normal saline; the positive drug group was given bosentan (100 mg/kg); Xiaoqinglong decoction 15, 10 and 5 g/kg was given, respectively, in the high, medium and low dose groups; once daily for 30 days. The mean pulmonary artery pressure (mPAP) and right ventricle systolic pressure (RVSP) were then measured with right heart catheterization and the right ventricle hypertrophy index (RVHI) was assessed; ET-1 and nitric oxide (NO) levels were determined by radioimmunoassay. Compared with the control group, the levels of mPAP, RVSP, RVHI and ET-1 were significantly increased in the PAH model group [mPAP (mmHg, 1 mmHg ≈ 0.133 kPa): 33.20±1.04 vs. 13.20±1.03, RVSP (mmHg): 62.40±1.54 vs. 24.20±1.02, RVHI: 42.90±2.51 vs. 25.40±2.01, ET-1 (ng/L): 100.80±20.34 vs. 81.50±13.84, all P < 0.05], while NO levels were significantly decreased (mmol/L: 23.20±1.81 vs. 31.70±1.49, P < 0.05). Compared with the PAH model group, the levels of mPAP, RVSP, RVHI and ET-1 in the positive drug group and high, medium, low dose groups of Xiaoqinglong decoction were significantly decreased [mPAP (mmHg): 25.50±0.84, 26.90±0.74, 27.10±1.19, 29.10±0.75 vs. 33.20±1.04, RVSP (mmHg): 54.40±5.14, 50.10±1.67, 53.10±1.05, 56.60±1.07 vs. 62.40±1.54, RVHI: 41.10±1.19, 31.20±1.67, 31.30±1.89, 40.30±1.88 vs. 42.90±2.51, ET-1 (ng/L): 70.70±7.89, 69.90±2.92, 71.70±4.32, 73.90±5.19 vs. 100.80±20.34, all P < 0.05], while NO levels were significantly increased (mmol/L: 32.50±2.06, 34.70±1.16, 32.70±1.33, 30.10±1.19 vs. 23.20±1.81, all P < 0.05), and with the increased dose of Xiaoqinglong decoction, the change was more obvious, and the effect was better in the high-dose group. Xiaoqinglong decoction can reduce rats PAH by regulating ET-1 and NO levels in a dose-dependent manner.

Isobaric tanks system for carbon dioxide energy storage – The performance analysis

The paper presents the results of thermodynamic and economic analysis of a compressed carbon dioxide energy storage installation using a novel solution, i.e. isobaric carbon dioxide tanks. The solution assumes the installation of low-pressure and high-pressure vessels in such a way that they are isobaric so that during the process of compression and expansion of gas there will be no need to use throttling valves to establish a constant level of pressure before the compressor and expander. The throttling valves using decrease the round-trip efficiency of the system by generating losses in the energy balance. The article presents the results of calculations of tank main geometry features also the pressure dependence of carbon dioxide in the high-pressure tank to the low-pressure tank. Thermal energy storage and a single-stage compressor and expander are considered in the energy storage system. A thermodynamic analysis was carried out to determine the basic parameters of the installation, such as the maximum round-trip efficiency of the energy storage system, which was 76% for 220 kPa in low pressure and 28.2 MPa in a high-pressure tank. The maximum temperature calculated at the compressor outlet was 612 °C. Levelized cost of storage was determined at the level of 593.87€/MWh.

Analysis of a newly developed hybrid pneumatic powertrain configuration for transit bus applications

In the current study, a new hybrid compressed natural gas, liquid nitrogen-based powertrain configuration is developed and analyzed for more environmentally-benign transit buses. The conceptual design extracts power from high-pressure nitrogen via three-stage expansion air motors. When the high-pressure LN2 tank level is critically low, a hydraulic pump powered via a CNG-based internal combustion engine is utilized to repressurize the liquid nitrogen. At the end of the expansion process, low-pressure nitrogen is condensed via a helium-based cryocooler system and stored in a low-pressure tank. The performance of the present conceptual system is evaluated via energy and exergy approaches. The power requirements, fuel consumption ratios and CO2 emission ratios are presented with respect to driving modes. The utilization of different fuel types as a secondary energy source for the powertrain is comparatively evaluated. The effects of various design and operational parameters on the system performance are investigated through parametric studies. The proposed system can operate with energy and exergy efficiencies of 46.6% and 67.5%, respectively while emitting 0.0768 kg CO2 eq per kilometer in city driving at a speed of 40 km/h (11.11 m/s).

On-site solar powered refueling stations for green hydrogen production and distribution: performances and costs

Today, the hydrogen is considered an essential element in speeding up the energy transition and generate important environmental benefits. Not all hydrogen is the same, though. The “green hydrogen”, which is produced using renewable energy and electrolysis to split water, is really and completely sustainable for stationary and mobile applications. This paper is focused on the techno-economic analysis of an on-site hydrogen refueling station (HRS) in which the green hydrogen production is assured by a PV plant that supplies electricity to an alkaline electrolyzer. The hydrogen is stored in low pressure tanks (200 bar) and then is compressed at 900 bar for refueling FCHVs by using the innovative technology of the ionic compressor. From technical point of view, the components of the HRS have been sized for assuring a maximum capacity of 450 kg/day. In particular, the PV plant (installed in the south of Italy) has a size of 8MWp and supplies an alkaline electrolyzer of 2.1 MW. A Li-ion battery system (size 3.5 MWh) is used to store the electricity surplus and the grid-connection of the PV plant allows to export the electricity excess that cannot be stored in the battery system. The economic analysis has been performed by estimating the levelized cost of hydrogen (LCOH) that is an important economic indicator based on the evaluation of investment, operational &amp; maintenance and replacement costs. Results highlighted that the proposed on-site configuration in which the green hydrogen production is assured, is characterized by a LCOH of 10.71 €/kg.

Multi-Scale study of an innovative safety system for Pressurized water reactors

After the FUKUSHIMA accident, passive systems become an important issue for the new projects of Pressurized Water Reactor (PWR). In response to the demands of its partners, the CEA (French Commission for the Atomic Energy and Alternative Energy) has proposed suitable systems to deal with different accidental sequences. Then, it has dimensioned their components and modelled their integration in the reactor using the CATHARE system code. In particular, the CEA has worked on the ADS system (Automatic Depressurization System) devised to tackle with the well-known LOCA accident (Loss of Coolant Accident), resulting from a breach in the pipes of the primary circuit.Concretely, the ADS system is made up of a tank called IRWST (In-Containment Refueling Water Storage Tank), placed high in the containment, which has the role of achieving a safety passive injection to replace the conventional one using low-pressure pumps, during a LOCA accident. The ADS is in fact already present on the AP1000 reactor, the US PWR designed to be totally passive. The CEA has proposed to improve it by adding a LPWT tank (Low-Pressure Water Tank) pressurisable by steam issued from the pressurizer on the last line of the ADS system. It should allow a better core cooling by the additional water injection in the reactor core, anticipated in time compared to that of the IRWST.The CFD application in reactor safety studies, due to its high-level of accuracy, is now widespread. The CFD calculation is used to predict local fluid temperature in the different regions of a nuclear reactor in nominal conditions and transient situations. Local CFD calculation coupled with a component system code for the whole domain of the reactor is also a current approach (Guelfi et al.).The study presented here exclusively focuses on the LPWT water pressurization phase prior to its injection into the reactor core. Three approaches are exposed:- An analytical approach, in which one considers the pressurization of the volume of gas present in the tank without taking into account the liquid phase;- A system approach with the CATHARE thermal–hydraulic code which allows to describe at the same time the volume of gas and the volume of liquid contained in the tank;- A CFD approach using the NEPTUNE_CFD code to determine the local evolution of the quantities that characterize the system. This approach will notably make it possible to describe the movement of the interface and the velocity profile of the water vapor. It will also help to bring a better understanding of the physical phenomena involved during the LPWT water pressurization phase.At the end, these different approaches show that the increase in pressure by the steam injection is an interesting option to pressurize the water tank. On the other hand, the results of the pressure evolution obtained by the system approach are very close to those obtained analytically, in the absence of liquid phase. However, they are overestimated compared to the CFD approach, which, thanks to a better modeling of the condensation of the injected vapor, leads to a more realistic evaluation.

Design and Stress Analysis of Metalhydride Pressure Vessel

The article describes the design and strength calculation of a low-pressure steel tank, which is used for storage of hydrogen in a metal alloy based on Ti and Zr. An external liquid heat exchanger is considered in the design of the metal hydride tank. Strength calculations were performed to verify the selected wall thickness of the vessel and the wall thickness of the selected bottom type according to STN EN 13322-2 standard for the implementation of a metal hydride tank in operating conditions.

Thermodynamic assessment of the novel concept of the energy storage system using compressed carbon dioxide, methanation and hydrogen generator

The main aim of this paper is to characterize the concept of a novel energy storage system, based on compressed CO2 storage installation, that uses an infrastructure of depleted coal mines to provide required volume of tanks, and, additionally, hydrogen generators, and a methanation installation to generate synthetic natural gas that can be used within the system or taken out of it, e.g., to a gas grid. A detailed mathematical model of the proposed solution was built using own codes and Aspen Plus software. Thermodynamic evaluation, aiming at determining parameters, composition and streams in all the most important nodes of the system for the nominal point and when changing a defined decision variable δ (in the range from 0.1 to 0.9) was made. The evaluation was made based on the storage efficiency, volume of the tanks and flows of energy within the system. The storage efficiency in the nominal point reached 45.08%, but was changing in the range from 35.06% (for δ = 0.1) to 63.93% (for δ = 0.9). For the nominal value of δ, equal to 0.5, volume of the low-pressure tank (LPT) was equal to 132,869 m3, while of the high pressure tank (HPT) to 1219 m3. When changing δ these volumes were changing from 101,900 m3 to 190,878 m3 (for LPT), and from 935 to 1751 m3 (for HPT), respectively. Detailed results are presented in the paper and indicate high storage potential of the proposed solution in regions with underground mine infrastructure.

Improving deposition efficiency and inter-particle bonding of cold sprayed Cu through removing the surficial oxide scale of the feedstock powder

In cold spray, surficial oxide scale of the feedstock powder not only reduces the deposition efficiency of spraying powder, but also deteriorates the properties of the deposit due to its influence on inter-particle bonding. To simultaneously improve the deposition efficiency of spraying powder and the properties of the deposit, in this study, taking Cu as a typical material, acid pickling was used to remove the oxide scale on the surface of the as-received powder. During acid pickling, Cu powder particles were immersed into the acid alcohol solution and then dried in a low-pressure tank. Using the as-received powder and acid-pickled powder as the spraying powder, Cu deposits were prepared under the same spraying conditions. The deposition behavior of spraying powders, the microstructure and properties, including mechanical properties, conductivities and anti-corrosion behavior of the Cu deposits were systematically studied. Results show that acid pickling can effectively remove the oxide scale on the surface of the as-received powder and reduce the powder oxygen content from 0.12 wt% to 0.044 wt%, leading to an increase in deposition efficiency of the spraying powder from 74% to 84%. Although both the Cu deposits reveal dense microstructure and thereby show good anti-corrosion, the tensile properties and conductivities of Cu deposits, which are sensitive to the inter-particle bonding, decrease with increase of the oxygen content in spray powder. Cu deposit prepared by acid-pickled powder shows the superior tensile properties and conductivities, and the tests yielded the tensile strength of 245 MPa, Young modulus of 85 GPa, electrical and thermal conductivities of 90%IACS and 298 W·m−1·K−1. Therefore, it is an effective approach to improve the deposition efficiency of spraying powder and prepare high-property cold-sprayed metallic deposit simultaneously by using acid pickling to remove the surficial oxide scale of particle.

Experimental investigation of vortex tube for reduction air inlet of a reciprocating air compressor

A vortex tube that can be employed to lower the temperature of the inlet air of a 7.5 kW piston air compressor was designed and tested. The vortex tube reduces the air temperature by acting as a cold air generator that exchanges the temperature within the evaporator. The first step of the research method started with the design of nozzles of three sizes to be used for the vortex tubes in order to identify the most effective nozzle size, followed by the conducting of experiments to determine the energy saving procedures that can be applied to and affect the compressed air. The results of the experiments showed that the most effective design of the nozzle was able to decrease the temperature of the inlet air of the compressor by 8.3 °C. The calculation of the highest energy saving settings was 2.3% with 6.0 bar for the vortex tube and 0.0 bar for the low-pressure air tank. This savings was a result of a decrease in the pressure in the vortex tube or an increase in the low-pressure air tank's pressure level. Therefore, it was found that the energy efficiency can be improved by increasing the pressure to the vortex tube.