Synchronization in multi-motor hydromechanical systems

Introduction. The paper submits the analysis of existing design solutions of flow dividers used to synchronize hydraulic drives of working bodies of technological and mobile machines. The market demands for multithreaded throttle flow dividers without valves with the controlled division ratio, such as multi-axle vehicle chassis, are identified. The objective of the work was to analyze the possibility and rationale for developing a throttle four-way flow divider without valves with sensing elements of the Venturi tube type. The solution should provide the synchronicity of movement (rotation) of more than three working bodies of technological and mobile machines.Materials and Methods. A patent search for the designs of hydraulic flow dividers is carried out, and systems that require the division of the hydraulic fluid flow into more than two executive bodies are considered. An upgrade option, which allows dividing the flow into four branches, is proposed for the design of a three-channel throttle flow divider without valves.Results. The urgency of developing a multithreaded throttle flow divider without valves for application in industrial and mobile machines is validated. Two types of four-flow dividers are considered, their weaknesses are indicated. It is noted that the development of a multithreaded throttle flow divider based on the designs created in 1989 and 1991 will reduce the number of hydraulic pumps and get rid of the series connection of double-flow dividers. In this way, it is possible to reduce pressure losses in the hydraulic system and implement adaptive control of hydraulic motors of multi-motor mobile machines. The possibility to obtain a divider/combiner into four flows by adding an outlet chamber connected to the membrane chamber through a channel entering the Venturi nozzle on the basis of a three-flow throttle divider is shown. The principle of operation of such equipment is described.Discussion and Conclusions. The principles of construction of throttle flow dividers without valves are considered. An upgrade option is proposed to increase the number of division channels from three to four. However, to validate the operability of this design, a numerical analysis of the various modes of operation of the divider is required — calculation of the reduced volumetric stiffness of its working cavities. The information obtained can be used to modernize the hydraulic units of technological and mobile machines, increase their reliability, manufacturability, and efficiency. The issues that need to be solved in further research are identified.

Study of the reduction of the onset temperature in a loop-tube-type thermoacoustic prime mover using Conical Phase Adjuster.- Based study on the installation position and onset temperature of Conical Phase Adjuster -

In this report, we proposed the installation of a Conical Phase Adjuster (CPA) in a thermoacoustic prime mover as a method for reducing the onset temperature and investigated the effect of the installation position of CPA on the onset temperature using stability analysis. The onset temperature of CPA also was investigated experimentally by changing the installation position of CPA. As a result, when CPA was installed at 1000 mm from the high-temperature end of the stack, the onset temperature was 195 K lower than the onset temperature without CPA, that is, the installation of CPA in a loop-tube-type thermoacoustic prime mover reduced the onset temperature by 29 %. Comparing onset temperatures of PA had installed in a system, CPA is considered to have the same effect as PA because the onset temperature tendency of CPA to reduce at the installation position agrees with that of PA.

Effect of external sound superimposed on the self-excited oscillation in loop-tube thermoacoustic system

The influence of application of external sound to loop-tube type thermoacoustic system on the energy conversion efficiency is experimentally examined. The investigation is carried out by paying attention on the effect of loudspeaker (SP) set as external sound source. As a result, it is found that the setting of SP affects the sound field in the system and the amount of energy generation increases or decreases. The increasing or decreasing effect differs depending on the setting position of SP. Furthermore, it is confirmed that, provided SP is set near the node of particle velocity, the sound energy can be increased by more than the input power to SP, without changing the sound field in the tube. From these results it can be confirmed that, similar to straight-tube type thermoacoustic system, the energy conversion efficiency can be enhanced by setting SP at suitable position even in loop-tube type without end surfaces.

Investigation of Optimal Aspect Ratio and Optimal Number of Fins for Thermal Performance of Finned-Concentric-Tube Thermal Energy Storage

This research focuses on the enhancement of the heat transfer in the concentric tube type of thermal energy storage (TES). The collective influence of the aspect ratio and number of fins is investigated. First, an optimal aspect ratio of the concentric tube TES is found. Additionally, then, the optimal number of fins is found. This combined optimal configuration of TES is then compared with concentric tube TES without. Liquid fraction of the combined optimal configuration was increased by 100% for case of charging as compared to TES without fins.

Design of heat exchanger for the production of synthesis silica

This study aims to analyze and develop a heat exchanger (HE) application for the manufacture of silica nanoparticles synthesis from agricultural waste. This shell and tube-type HE is designed simply, but it still refers to the existing design rules. The design of a shell and tube type HE with one pass shell and tube with turbulence flow. The specifications of the HE apparatus are 1.93 m in shell length, 0.203 m in shell diameter, 0.020 m in inner tube diameter, 0.022 m in outer tube diameter, and 0.016 m in thickness. The results showed an effectiveness value of 66.38% with an impurity factor of 0.01314. This informed that although the shell and tube-typed HE does not meet the requirements and standards for being set in industrial applications, it can be useful as a learning method regarding the design process, working mechanism, and analyzing the performance of the HE.

Design of heat exchanger for the production of zinc imidazole framework-8 (ZIF-8) particles

The design of a heat exchanger is very effective to reduce total production costs, compared to buying a ready-made exchanger. This study aims to design a heat exchanger with a manual calculation analysis method to get dimension calculations of the heat exchanger. Dimension calculation of heat exchanger aims to determine the quality of the heat exchanger based on the overall heat transfer coefficient and the dirt factor that occurs in the heat exchanger. The designed heat exchanger is a shell and tube type with 1 (one) pass shell and 2 (two) pass tubes using water as hot fluid and cold fluid. The fluid flow is assumed to be the opposite. The results show the effectiveness of the heat exchanger reaches more than 50%. The performance of the designed heat exchanger is relatively good but it still does not meet the minimum requirements of the established dirt factor. This research can be useful as a learning method regarding the design process, working mechanism, and heat exchanger performance.

Review on the Performance Evaluation of Thermal Exchangers using Different Baffle Designs

The thermal performance of a heat exchanger depends upon various parameters like inlet temperature of hot fluid, type of hot fluid, type of cold fluid, the shape of baffles, the material of baffles, baffles angle, and property of ribs. Basically fluid flow and heat transfer characteristics largely depend upon the Reynolds number (Re). Reynolds number is basically the ratio of inertia force to viscous force. Re is only the factor by which we can decide whether the fluid is laminar or turbulent in shell and tube type of heat exchanger. The heat exchanger is an adiabatic device in which heat is transferred from one fluid to another fluid across a plate surface. In this paper, we have introduced some special types of triangular baffles with rectangular channels. The purpose of this apparatus is to enhance the performance of the heat exchanger. Heat exchangers, nowadays, are one of the most important heat & mass transfer apparatuses in industries like oil refining; heat treatment plants, electric power generation, etc. are long service life.

Effect of preexamination conditions in a centralized-testing model of non-invasive prenatal screening

Objectives Non-invasive prenatal testing requires the presence of fetal DNA in maternal plasma. Understanding how preexamination conditions affect the integrity of cell-free DNA (cfDNA) and fetal fraction (FF) are a prerequisite for test implementation. Therefore, we examined the adjusted effect that EDTA and Streck tubes have on the cfDNA quantity and FF. Methods A total of 3,568 maternal blood samples across Canada were collected in either EDTA, or Streck tubes, and processing metrics, maternal body mass index (BMI), gestational age and fetal karyotype and sex were recorded. Plasma samples were sequenced using two different sequencing platforms in separate laboratories. Sequencing data were processed with SeqFF to estimate FF. Linear regression and multivariate imputation by chained equations were used to estimate the adjusted effect of tube type on cfDNA and FF. Results We found a positive association between cfDNA quantity and blood shipment time in EDTA tubes, which is significantly reduced with the use of Streck tubes. Furthermore, we show the storage of plasma at −80 °C is associated with a 4.4% annual relative decrease in cfDNA levels. FF was not associated with collection tube type when controlling for confounding variables. However, FF was positively associated with gestational age and trisomy 21, while negatively associated with BMI, male fetus, trisomy 18, Turners syndrome and triploidy. Conclusions Preexamination, maternal and fetal variables are associated with cfDNA quantity and FF. The consideration of these variables in future studies may help to reduce the number of pregnant women with inconclusive tests as a result of low FF.