Thermally controlled microfluidic back pressure regulator

By using the temperature dependence of viscosity, we introduce a novel type of microfluidic lab-on-a-chip back pressure regulator (BPR) that can be integrated into a micro-total-analysis-system. A BPR is an important component used to gain pressure control and maintain elevated pressures in e.g. chemical extractions, synthesis, and analyses. Such applications have been limited in microfluidics, since the back pressure regularly has been attained by passive restrictors or external large-scale BPRs. Herein, an active microfluidic BPR is presented, consisting of a glass chip with integrated thin-film heaters and thermal sensors. It has no moving parts but a fluid restrictor where the flow resistance is controlled by the change of viscosity with temperature. Performance was evaluated by regulating the upstream pressure of methanol or water using a PID controller. The developed BPR has the smallest reported dead volume of 3 nL and the thermal actuation has time constants of a few seconds. The pressure regulation were reproducible with a precision in the millibar range, limited by the pressure sensor. The time constant of the pressure changes was evaluated and its dependence of the total upstream volume and the compressibility of the liquids is introduced.

Effects of working conditions on the operating characteristics of an injection system applied on CNG fueled vehicles

A model-based study is conducted to examine the operating characteristics of an injection system applied on CNG fueled vehicles. This injection system is a combination of an electric pressure regulator, a rail tube, and a solenoid injector. The electric pressure regulator has a great potential to be widely used in injection systems of natural gas-fueled engines due to its flexible operation, which can help to improve the engine performance and reduce emission. This paper presents a simulation study using mathematical models to describe and analyze the operating characteristics of the gaseous fuel injection system, in which models of electric pressure regulator, solenoid fuel injector, and control model for electric pressure regulator are presented. The simulation results are compared with experimental data to validate the simulation models. Effects of working conditions, including coil resistance of the electric pressure regulator, inlet gas pressure, and set pressure in the rail tube, on the operating characteristics of the gaseous fuel injection system are investigated. Simulation results show that when the coil resistance of the electric pressure regulator is increased from 3.1 Ω to 4.1 Ω, the maximum fluctuation of the controlled gas pressure in the rail tube is reduced from 0.017 to 0.012 MPa, respectively. By decreasing the inlet gas pressure of the electric pressure regulator from 2.5 to 2.3 MPa, the controlled gas pressure in the rail tube is more stable with the maximum fluctuation significantly reduced from 0.012 to 0.002 MPa, respectively, which leads to stability in injection flow rate. The increase of set pressure in the rail tube from 0.5 to 0.7 MPa can help to improve the stability of the controlled gas pressure in the rail tube with the maximum fluctuation respectively reduced from 0.002 to 0.001 MPa.

DEVICE FOR CHECKING AND CALIBRATING INDICATORS OF THE RESERVE TIME OF CONSCIOUSNESS PRESERVATION BY A PERSON IN CONDITIONS OF HYPOXIA

Для обеспечения надежного функционирования индикаторов резервного времени сохранения сознания человеком в условиях гипоксии разработан специальный прибор для их поверки и калибровки. Прибор включает регулятор давления, табло для индикации эталонного давления, табло для индикации резервного времени сохранения сознания, шланг с разъемом для соединения с датчиком барометрического давления, компрессор, регулятор давления и микропроцессор. Разработанный прибор обеспечивает возможность контроля работоспособности средств коллективного и индивидуального информирования экипажа пассажиров воздушных судов о величине предельного резервного времени сохранения сознания в чрезвычайных ситуациях высотных полетов. To ensure the reliable functioning of the indicators of the reserve time of consciousness preservation by a person in conditions of hypoxia, a special device for their verification and calibration has been developed. The device includes a pressure regulator, a tableau for indicating the reference pressure, a tableau for indicating the standby time of consciousness, a hose with a connector for connecting to the barometric pressure sensor, a compressor, a pressure regulator and a microprocessor. The developed device provides the ability to monitor the performance of the means of collective and individual informing the crew of aircraft passengers about the value of the maximum reserve time for maintaining consciousness in emergency situations of high-altitude flights.

A Study on the Effects of Plug Shape on Operating Performance of an Electric Pressure Regulator Applied for Gaseous Fueled Vehicles

A model-based study was conducted to examine the effects of plug shape on electromagnetic force and dynamic response of an electric pressure regulator (EPR) applied for gaseous fueled vehicles. Mathematical models were established to describe the operation of the EPR, including mechanical and electrical models. A two-dimensional (2D) symmetric model of the EPR was built in Maxwell software to simulate the electromagnetic force under the effects of plug shape. Afterward, the 2D symmetric model of EPR with the electromagnetic force calculated was imported into Simplorer software to simulate the dynamic response of the EPR based on the influence of plug shape. The shape of plug in the EPR was changed through the dimension parameters denoted by dimension (h) and slope angle (). The simulation results show that the electromagnetic force and dynamic response of the EPR can be optimized when h and  are selected at 3mm and 480, respectively.

Dynamics of Working Processes in Automatic Direct-Acting Pressure Regulators of Pneumatic Spacecraft Systems

The purpose of the study was by means of modern software to explore working processes taking place in automatic direct-acting pressure regulators of pneumatic spacecraft systems. As a result, we developed a general mathematical model of the pressure regulator. The design of the regulator is shown in the form of a block diagram, composed of a set of channels, cavities, and stages. The elements of the block diagram are interconnected by the basic laws of conservation of energy and mass. The mathematical model was evaluated in the Amesim software package. Findings of the full-scale and computational experiments led to the conclusions about the effect the heat exchange between the working fluid and the environment produces on the parameters of the pressure regulator, and about the use of the Amesim software package for further research of working processes in the valve units of pneumatic systems.

​Weed Control using Pre-emergence Herbicide Strip Application System Along with Sowing/Planting Devices

A 6-row pre-emergence herbicide strip-application system was designed and developed at ICAR-CIAE, Bhopal as an attachment to inclined-plate planter to apply herbicide at the time of sowing in widely spaced crops to control weeds along the crop rows, often not possible in mechanical weeding. It consisted of a frame on which 6 flat fan spray nozzles were mounted by means of clamps, a single action piston pump with 9 l/min capacity, pressure regulator valve and pressure gauge and pressure pipes. The spacing between the spray nozzles, angle and height of spray nozzles can be varied by adjusting the clamps. The developed system has ability of strip as well as blanket application of herbicide. The same machine can be used as post-emergence herbicide/pesticide applicator after the removal of furrow openers and increasing the height of nozzles from the ground. The machine was tested and evaluated during Kharif season for soybean and pigeon pea crops. The field capacity of the developed system was found to be 0.4 ha/h. The operating cost of the pre-emergence herbicide applicator with inclined plate planter was worked out as Rs 1350/- per ha. It can save about 40-50% herbicide.