Curtain System Research Articles

Probabilistic analysis of water-sealed performance in underground oil storage considering spatial variability of hydraulic conductivity

For underground water-sealed oil storage, the spatial variability of the surrounding rock has a significant impact on the water-sealed effect of a water curtain system. This study presents a methodology for the probabilistic analysis of water curtain performance in underground oil storage, considering the spatial variability of hydraulic conductivity of the surrounding rock based on field data. Anisotropic random fields representing the spatial variability of hydraulic conductivity were established through spatial statistical analysis of field data and introduced into the finite element model of underground oil storage for water-sealed reliability analysis. The water-sealed performance of different water curtain system schemes was studied using Monte Carlo simulation (MCS). The results showed that the difference between the horizontal spatial correlation and the vertical spatial correlation of the surrounding rock has a significant impact on the water-sealed effect of the water curtain system. An excessively large pressure of water curtain boreholes provided a small contribution to improving water curtain performance. The distance between the water curtain holes and the caverns had the less significant affecting the water-sealed reliability of the storage cavern. Finally, the optimal design of the water curtain system is discussed. This study provides valuable insights and a theoretical basis for the optimisation of water curtain system design parameters for underground water-sealed oil storage.

Low temperature heating system for greenhouses based on enclosed water curtain and liquid foam insulation

A greenhouse water curtain heating system allows heating of the greenhouse by low-temperature water, which can be obtained from residual waste heat sources. The water curtain can be applied on the outside of the greenhouse roof or enclosed between two foils. But also enclosed water curtains suffer from high heat losses, which limits the integration of low temperature waste heat sources. An effective way of reducing the heat losses is to combine the water curtain system with retractable liquid foam enclosed between two foils. But until now, a systematic evaluation of the thermal performance of such system combination is still lacking. Thus, this study aims to fill in this research gap by evaluating the heat transfer characteristics of a double-foil greenhouse roof section installed with a combined water curtain and liquid foam system. Experimental tests have been conducted under a wide range of temperature scenarios in a climate chamber where the heat loss and heat gains from the water curtain is measured. The results have been compared with the data in the existing studies. This study revealed that combining the water curtain system with liquid foam, reduces the heat losses by half compared to using just the water curtain: the heat loss coefficient was reduced from 4.4 W·m−2·K−1 down to 2.0 W·m−2·K−1. The heat losses through the roof using the combined system are also lower than the heat losses from a double foil greenhouse with other heating systems. An average water curtain temperature of 5.1 °C above the inside greenhouse temperature can compensate for the heat losses through the roof at an outdoor temperature of −19 °C. Based on the study results, recommendations for market implantation of this technology are provided. This study confirms energetic benefit of combining water curtains and the liquid foam technology.

Research on the Changing Law of Tunnel Temperature Field and the Application of Air Curtain System in Cold Regions

In this study, a tunnel temperature field model test bed is built according to the similarity principle to study the variation law of temperature in the tunnel in the cold season. According to the variation law of temperature in the tunnel, a new active thermal insulation measure, namely, an air curtain system, is developed. According to the principle of flow function superposition and heat balance, the governing equation of air curtain system is obtained. Taking the Zhengpantai tunnel as an example, the feasibility of the air curtain system is verified, and the jet angle of air curtain is optimized. The research results show that outside temperature and surrounding rock temperature are the main factors affecting the temperature field of tunnels in cold regions. The calculation results show that the air curtain system can effectively prevent tunnel freezing damage. The optimal jet angle of air curtain system should be 30°–40°. When the outside temperature is extremely low, multiple air curtains can be used in series to heat the temperature in the tunnel, and it is recommended that the distance between the two air curtains is not less than 20 m.

New Technology for Preventing and Controlling Air Leakage in Goaf Based on the Theory of Wind Flow Boundary Layer

Air leakage in the goaf is a fundamental reason for the high-temperature heat damage of the coal mining face and the gas concentration in the upper corner exceeding the limit. Combined with the boundary layer theory, this study analyzes the airflow state of the coal mining face. We propose installing a new air curtain system to prevent air leakage in the goaf. The length of the intake air curtain is determined by solving the theoretical equation. Numerical simulation is used to study different layout schemes of air curtains, and the spatial distribution law of different air volumes inside the working face is analyzed. The simulation results are compared with the field-measured data. The results show that when the length of the air curtain on the air inlet side is 20 m, the wind flow on the working face can be approximated as a state of attached jet, and a diffuse turbulent flow area will be formed outside the air curtain. Gas concentration will increase in this area. The air leakage prevention effect is best when the air curtains with a length of 20 m for the inlet air and 10 m for the return air are arranged at both ends of the working face. This air curtain system can reduce the temperature of the working face and the gas concentration in the upper corner and has certain guiding significance for the air leakage prevention work in the goaf.

Seawater intrusion into an underground water-sealed oil storage cavern: Effects of water curtain system, hydraulic conductivity and dispersivity

The construction of underground facilities in coastal area usually results in seawater intrusion, which affects the service life of underground facilities. Considering the effects of different water curtain systems, hydraulic conductivity, and dispersivity, the dynamic seawater intrusion characteristics of an underground water-sealed oil storage cavern in coastal area have been obtained by numerical simulation based on multi-physical field coupling theory. The results show that in terms of the extent and scope of seawater intrusion, compared with only setting horizontal water curtain, adding vertical water curtain is more effective in controlling seawater intrusion; as the depth of the vertical water curtain increases, the effect of preventing seawater intrusion is better. When the equivalent hydraulic conductivity is the same and the anisotropy ratio of hydraulic conductivity increases, the extent of seawater intrusion is weaker; when the anisotropy ratio of hydraulic conductivity is the same and the equivalent hydraulic conductivity increases, the extent of seawater intrusion is weaker. As the longitudinal dispersivity becomes larger, the extent of seawater intrusion is weaker. The water-sealed safety and water inflow of the underground water-sealed oil storage cavern have been analyzed. The research results could provide a theoretical basis for the seawater intrusion problem faced by the construction of underground water-sealed oil storage caverns in coastal area, and have a certain guiding effect on the excavation of underground facilities in coastal area.

Blocking effect of desktop air curtain on aerosols in exhaled breath

A desktop-type air curtain system (DACS) capable of being installed on a desk to protect healthcare workers from infectious diseases was developed. Pseudo-exhaled air containing aerosol particles emitted from a mannequin was blown toward the air curtain generated by the DACS. The aerosol blocking effect of the DACS was investigated using particle image velocimetry measurements. A scenario in which the arm of a patient in the blood collection room is placed on the gate of the DACS was also investigated. Air curtain flow was maintained inside the gate of the DACS. The aerosol particles approaching the DACS were observed to bend abruptly toward the suction port without passing through the gate, signifying that the aerosol particles were blocked by the air curtain flow. When the arm of the patient was placed on the gate of the DACS during blood collection, the airflow above the arm was disrupted. However, the aerosol blocking performance remained unaffected. We envisage that this system will be useful as an indirect barrier not only in the medical field but also in situations where sufficient physical distance cannot be maintained, such as at the reception counter.

Study on the extension length of horizontal hydrogen jet fires under the action of water curtain

Hydrogen is a clean fuel, however, the potential leakage and jet fire accidents should be considered seriously. This study focuses on the burning behaviors of horizontal hydrogen jet fires under the action of a water curtain system. The experiments of horizontal hydrogen jet fires with fuel flow rate ranging from 30 to 80 L/min and initial pressure of water curtain ranging from 2 to 4 MPa were conducted. The experimental results show that the shape of the hydrogen jet flame expanded on the water curtain is elliptical at different conditions. The extension area and extension length of jet fire at the water curtain increase with increasing fuel flow rate. The extension area and length decrease with the separation distance and the initial pressure of the water curtain, however, show different variation tendencies with fuel flow rate. A new dimensionless heat release rate is proposed to estimate the flame extension length by accounting for the effects of the initial pressure of water curtain and the separation distance between the jet nozzle and water curtain, which is useful for fire prevention design in the hydrogen storage area.

Water-sealing performance assessment of the water curtain system in underground water-sealed oil-storage caverns

Water-sealing performance assessment of the water curtain system in underground water-sealed oil-storage caverns

Water quality control in a water curtain system at an underground rock cavern of liquefied petroleum gas storage site (Kurashiki, Japan)

Water quality control in a water curtain system at an underground rock cavern of liquefied petroleum gas storage site (Kurashiki, Japan)

Development of Desktop Air Curtain System to Block Aerosols in Exhaled Breath

A desktop-type air curtain device capable of being installed on a desk to protect healthcare workers from infectious diseases was developed. Pseudo-exhaled air containing aerosol particles emitted from a mannequin was blown toward the air curtain generated by the air curtain device. The aerosol blocking effect of the air curtain device was investigated using particle image velocimetry measurements. Air curtain flow was maintained inside the gate of the air curtain device. The aerosol particles approaching the air curtain device were observed to abruptly bend towards the suction port without passing through the gate, signifying that the aerosol particles were blocked by the air curtain flow.

Automated Microclimate Regulation in Agricultural Facilities Using the Air Curtain System.

Creating and maintaining the microclimate in livestock buildings is associated with numerous engineering and technical challenges. Together with adequate feeding, the microclimate determines the health, reproductive ability, and production potential of the animals (obtaining a maximum amount of high-quality products). One of the deciding steps in improving the parameters of microclimate, i.e., temperature and humidity in agricultural facilities, particularly in livestock buildings, is to develop reliable and highly efficient air curtains in the vestibules. The objective of the manuscript is to investigate the parameters of the microclimate in livestock buildings using the air curtain, supported by automation and ICT technologies for rational operating modes. The presented theoretical and experimental studies on improving the microclimate parameters in livestock buildings were carried out using an innovative air curtain system. Its power is calculated based on the dimensions of the room, and the flow rate of warm air near the floor level is three times lower than at the installation site. The use of air curtains reduces consumption of thermal energy needed to maintain an optimal microclimate for livestock by 10–15%. Furthermore, the use of an automated digital control system maintains an optimal microclimate in the building. The developed energy-saving system for creating an optimal micro-climate in livestock buildings using air curtains was tested in a pigsty of the Research and Training Farm “Vorzel” of the National University of Life and Environmental Sciences of Ukraine, located in the Kiev region. The developed automated microclimate system using air curtains significantly improves the microclimate parameters and significantly reduces power consumption. The system can be further developed by adding remote control based on the Internet of Things (IoT) technology.

Effectiveness of personalized air curtain in reducing exposure to airborne cough droplets

To minimize infection risk of airborne transmission during close contact, a personalized air curtain (PAC) system was proposed to protect users from airborne droplets. This work investigated the performance of PAC in reducing exposure to airborne droplets through two thermal manikins in close proximity (0.82 m). A cough generator was put into one of the manikins (an infected person) to release cough droplets to simulate coughing activities. Concentration of airborne droplets in the inhalation zone of the other manikin, as a healthy person (HP), was measured. The effect of PAC with different flow rates (from 9 L/s to 27 L/s) and distances to the HP (15 cm–65 cm) on exposure to airborne droplets was investigated. The performance of PAC was further compared with that of personalized ventilation (PV), integrated PAC-PV, and partitions. Visualization experiments were performed to observe the interaction between the cough jet and PAC, PV, PAC-PV, and partitions. The results showed that exposure reduction caused by PAC was from 42% to 87% considering the flow rate and distance between HP and PAC. When the PAC velocity increased to ‘critical velocity’, i.e., 5 m/s, the exposure reduction was nearly stable and the distance between PAC and HP has almost no influence on the exposure reduction. Besides, exposure reduction of integrated PAC-PV was between 94% and 98%, showing a quite good performance in reducing airborne droplets. The results indicated that PAC and PAC-PV could be used as mitigation measures to protect users and reduce exposure to airborne droplets.

Infection Control Improvement of a Negative-Pressurized Pediatric Intensive Care Unit.

The COVID-19 pandemic caused by the novel SARS-CoV-2 virus raises alarming concern around the healthcare facilities due to the significant increase in patient inflow. Negative-pressurized isolation rooms have been utilized in various health care facilities to isolate the patients from active community contact. Several studies have highlighted isolation rooms improvement. However, limited knowledge is available regarding the isolation room facilities for pediatric intensive care units (PICU) to accommodate more than one pediatric patient. In this aspect, this study investigates a negative-pressurized isolation facility in PICU with minimal design modifications with the possibility that it can accommodate more than one pediatric patient. The field measurement tests were conducted to ensure the design compliance of Taiwan CDC. Then, computational fluid dynamics (CFD) was further utilized to numerically evaluate the HVAC system role and the ventilation performance towards infection control. A protected air-jet curtain system with a new ventilation layout was proposed through this study to enhance the protection for both pediatric patients and medical staff. The concentration decay was monitored and recorded within 900 s to evaluate the performance. The concentration can be reduced to 504 ppm for case 1, 620 ppm for case 2, 501 ppm for case 3, and 486 ppm for case 4. In addition, the injected bioaerosol particles could be well diluted dealing with two patients presents a good performance. The results revealed that this proposed configuration could feasibly accommodate two patients with a significant contamination control to protect the medical staff and patients.

Performance evaluation for a coupled push–pull ventilation and air curtain system to restrict pollutant dispersion in a factory building

One of the major challenges in rapid industrial development is to maintain a healthy and safe working environment, because the working environment in factories is often contaminated with harmful pollutants, such as the paint mist particles generated in manual painting factories. To effectively dilute or remove paint mist particles distributed in the working environment, this investigation developed a ventilation system by combining a uniform push–pull ventilation system with an air curtain. The performance of the developed ventilation system in restricting paint mist particle dispersion was evaluated using computational fluid dynamics based on Reynolds-averaged Navier-Stokes equations, re-normalization group k - ε equations and discrete phase particle equations. Both two- and three-dimensional transient simulations were carried out by ANSYS Fluent (Version 16.0). The numerical results showed that the dispersion of paint mist particles is higher with a higher jet velocity of the air curtain but lower with a higher air supply velocity of the uniform push–pull ventilation. Furthermore, the painting position also affected the mist pollutant concentration distribution, although the developed ventilation system was operated under the same conditions. A reasonable combination of the uniform push–pull airflow and air curtain could better control the dispersion of the paint mist particles for different painting positions; this could potentially improve the indoor air quality and environmental health in painting factories, as compared with existing ventilation systems. • A coupled uniform push–pull ventilation and air curtain system is developed. • Push-pull airflow, air curtain and sources act together in mist particle dispersion. • Different parameters in controlling escape ratio of mist particle are not consistent. • A reasonable combination of push-pull airflow and air curtain is viable to reduce escape.

Geochemical monitoring of deionized seawater injected underground during construction of an LPG rock cavern in Namikata, Japan, for the safety water curtain system

An underground liquified petroleum gas (LPG) storage facility was constructed between 2003 and 2013 in Namikata, Imabari City, Ehime Prefecture, Japan, to increase domestic LPG stockpiles. The most important issue during construction and operation of this facility is gas leakage prevention. To thwart water leakage, the water curtain system was constructed according to design standards, and a large amount of deionized seawater (seal water) was continuously injected into the rock mass around the cavern to keep the water level constant during both construction and operation. It is possible to distinguish three end member waters (existing groundwater, seawater or fossil seawater, and seal water) using the salinity and isotope (δ18O) difference because seal water injected underground has almost the same δ18O value as seawater. In this study, continuous observation is carried out using the geochemical techniques for flow analysis with a mixing proportion of three end-members in the initial construction period (April 2005 to March 2006) of the LPG underground storage facility. It is determined that existing groundwater and fossil seawater originally distributed in this region are partly replaced by seal water in the cavern.

SPH simulation of hydrodynamic responses for two novel types of silt curtain under combined wave-current conditions

Traditional silt curtain is a kind of commonly-used impermeable device for short-term control of suspended solids or turbidity in the water column generated during dredging operations. It is attempted to innovatively apply the silt curtain to more violent hydrodynamic conditions, such as functioning as an isolation structure for preventing sediment transportation into channels and harbor basins in a combined wave and current environment. The Weakly Compressible Smoothed Particle Hydrodynamics (WCSPH) code of Shi and Li et al. (2018), after incorporating an overlapped particle method (OPM), was applied to simulate the responses of a flexible impermeable curtain system as a thin-walled structure fixed to the sea bottom and moving violently under the action of static water pressure heads along and combined with waves. It is found that the modeled results of tensions in the curtain of a Silt Curtain System (SCS) working in emerged mode are in good consistency with the theoretical and experimental results and the SCS in submerged mode would be subject to much smaller tensions than in emerged mode. A large influx rate of q = 0.053 m3/s/m would enhance the wave-induced component of curtain tensions in the submerged mode. When subject to waves, the SCS in emerged mode imposes much more significant influence on wave transmission than in submerged mode, while the SCS in emerged mode produces lower horizontal oscillation ratio than in submerged mode.

Discussion on the optimal spacing of water curtain holes in cavern reservoir

Vertical and horizontal water curtain holes can be effectively used to seal underground oil storage caverns. However, the density of hole spacing affects the water sealing effect of the water curtain system. Based on the basic theory of Darcy’s law, this study established a three-dimensional model involving a main oil storage cavern, water curtain tunnel, water curtain hole, and surrounding rock mass. Different seepage effects on water curtain holes under different spacing are calculated and analyzed using a numerical analysis method. The optimal water curtain hole layout is finally determined by comparing the recommended spacing with the minimum water head difference.

Hydraulic Conductivity of Rock Masses Surrounding Water Curtain Boreholes for Underground Oil Storage Caverns

The assessment of the groundwater flow rate around the cavern periphery is a critical requirement for the design of underground water-sealed oil storage caverns and commonly made through seepage analysis, where a reasonable estimation of the hydraulic conductivity of the host rock is the key issue. However, it is a challenge to accurately determine the hydraulic conductivity of natural rock masses owing to their heterogeneous and anisotropic nature. The underground storage cavern project has a unique favorable condition in that there is a water curtain system that can provide considerable hydraulic test data for inferring hydraulic parameters; however, no well-established method has ever been proposed to exploit these data for characterizing heterogeneity in hydraulic conductivity. This study presents a new approach to evaluate the spatial variation of hydraulic conductivity using water curtain borehole data. This approach treats the peripheral region of each borehole as a homogenous unit with a particular equivalent permeability coefficient that can be back-calculated from the measured injection flow rate of the borehole using a numerically established empirical formula. Besides, the impact of curtain gallery drainage, occurring in the construction stage, on the seepage field was investigated while the effect of the rock fracture configuration on hydraulic conductivity assessment was examined. The proposed method enables robust and accurate mapping of heterogeneity in the hydraulic conductivity of host rocks and provides a new idea of effectively utilizing hydro-geological test data to derive the hydraulic conductivity of rock masses surrounding water-sealed storage caverns.

Automatic Curtain Design With LDR And IR Sensors at The BAPPENDA Kebumen

The Regional Revenue Management Agency of Kebumen Regency is a government agency that manages regional revenue in Kebumen Regency. The design of automatic curtains is expected to make it easier for office employees to use the facilities. This automatic curtain uses a flow chart and programming logic in designing programs for the light intensity of the IR sensor and the LDR sensor as an automatic curtain indicator using a remote. The design of the automatic curtain consists of an IR sensor and an LDR sensor as input, Arduino UNO as a processor, Relay as a component that transmits commands from the Arduino UNO to the motor, and motor as the output of this project. Automatic curtains at BAPEDA Kebumen can make it easier for employees to use office facilities to make them more durable, more comfortable, and more effective during working hours or on holidays because of the automatic curtain system that has been made.

Research on the plume stability of air bubble curtains under low transverse flow velocity environment in dredging engineering

Air bubble curtain anti-fouling systems, which meet both the environmental standards of suspended solids diffusion and navigation requirements, have unique advantages in environmental dredging technology. Through the bubble plume formed by dense bubble hole jets, the bubble curtain blocks the material exchange between the designated area and other areas in the water to prevent the diffusion of suspended pollutants and protect the water environment. The protection efficiency of the bubble curtain is determined by the fusion of the bubble flow in the rising process and the stability of the plume under the action of a cross flow. The feasibility of a bubble curtain in field engineering is evaluated in this paper. Using two fluid models, the time-varying process of bubble fusion and migration in a bubble plume is analyzed. The dynamic behavior characteristics of the bubble plume are obtained, and the factors influencing the stability of the bubble plume are quantitatively described. The results show that the turbidity of the water body decreases in front of and behind the bubble curtain, which proves that the bubble curtain system is practical in dredging engineering. The number, size range and median value of bubbles in the flume are related to the ventilation pressure and pipe structure. There are three different phenomena in the half-width of the bubble plume at different heights. With the general linear model, it is concluded that the fusion height of the bubble plume is the most sensitive to the change in the bubble tube hole spacing and that the migration characteristics of the bubble plume are most significantly affected by the air flow at the bubble hole. The mechanical analysis of the plume stability shows that the Weber number is the most important parameter affecting the failure of the bubble curtain.