Fluid Particle Trajectories in Stirling-Cycle Machines

1978 ◽  
Vol 20 (1) ◽  
pp. 1-10 ◽  
Author(s):  
A. J. Organ
Keyword(s):  
Particle Trajectory ◽  
Fluid Particle ◽  
Working Fluid ◽  
Piston Motion ◽  
Stirling Cycle ◽  
Working Space ◽  
Specific Entropy ◽  
Set Up ◽  
Limiting Case ◽  
The Ideal

Equations are set up by means of which arbitrarily selected particles of working fluid may be ‘tracked’ continuously throughout a cycle. Pressure is assumed to be instantaneously uniform, but account is taken of variable working space temperatures. Fluid particle trajectory maps are presented for machines of two types. One has opposed pistons following the ‘ideal’, discontinuous motion. The other has coaxial piston and displacer actuated by the rhombic drive mechanism. For the limiting case of isothermal phases, pressure is plotted against specific volume, and temperature against specific entropy for selected tracked particles. Thus it is deduced that, even when the unswept volume is taken to be zero, and piston motion to be discontinuous, it is not possible to draw either a unique p-v diagram or a unique t-s diagram for any practical embodiment of the Stirling cycle. It is demonstrated that such relationships may be viewed instead as summations of an infinity of p-vs or t-s relationships, that is, one for each discrete working fluid element.

The World Underfoot

2018 ◽  
Author(s):  
Hallie M. Franks
Keyword(s):  
The Political ◽  
Classical Period ◽  
Social Fabric ◽  
Physiological Reaction ◽  
The Social ◽  
The World ◽  
Foreign Land ◽  
Social Gathering ◽  
Set Up ◽  
The Ideal

In the Greek Classical period, the symposium—the social gathering at which male citizens gathered to drink wine and engage in conversation—was held in a room called the andron. From couches set up around the perimeter of the andron, symposiasts looked inward to the room’s center, which often was decorated with a pebble mosaic floor. These mosaics provided visual treats for the guests, presenting them with images of mythological scenes, exotic flora, dangerous beasts, hunting parties, or the specter of Dionysos, the god of wine, riding in his chariot or on the back of a panther. This book takes as its subject these mosaics and the context of their viewing. Relying on discourses in the sociology and anthropology of space, it argues that the andron’s mosaic imagery actively contributed to a complex, metaphorical experience of the symposium. In combination with the ritualized circling of the wine cup from couch to couch around the room and the physiological reaction to wine, the images of mosaic floors called to mind other images, spaces, or experiences, and, in doing so, prompted drinkers to reimagine the symposium as another kind of event—a nautical voyage, a journey to a foreign land, the circling heavens or a choral dance, or the luxury of an abundant past. Such spatial metaphors helped to forge the intimate bonds of friendship that are the ideal result of the symposium and that make up the political and social fabric of the Greek polis.

Stirling's air engine—a thermodynamic appreciation

2000 ◽  
Vol 214 (4) ◽  
pp. 511-536 ◽  
Author(s):  
A J Organ
Keyword(s):  
Particle Trajectory ◽  
Temperature Response ◽  
Fluid Particle ◽  
Drive Mechanism ◽  
Specific Output ◽  
Crank Angle

Stirling's original engine is remarkable for having been the first application of the thermal regenerator—and an instant technological success. While the patents and their intriguing history are the normal focus of study, this paper shifts attention to the insights afforded by reconstructing the thermodynamic personality of the engine itself. The kinematics of the drive mechanism are recovered, and volume variations determined as a function of crank angle. Recently developed thermodynamic tools are introduced and applied to the construction of the fluid particle trajectory map. The map forms the integration grid for calculation of the temperature response of the regenerator. The claim for 2 bhp from the original engine is explored. Potential is identified for an up-to-date version of Stirling's elegant concept in the form of cheap quiet power units of attractive specific output.

GIS Based Multi-Criteria decision support system and machine learning for Hospital Site Selection case study Oran - Algeria

2022 ◽  
Vol 14 (1) ◽  
pp. 0-0
Keyword(s):  
Site Selection ◽  
Decision Makers ◽  
Analysis Method ◽  
Automatic Learning ◽  
Hospital Site ◽  
Set Up ◽  
High Level ◽  
Selection Of ◽  
The Ideal

The selection of hospital sites is one of the most important choice a decision maker has to take so as to resist the pandemic. The decision may considerably affect the outbreak transmission in terms of efficiency , budget, etc. The main targeted objective of this study is to find the ideal location where to set up a hospital in the willaya of Oran Alg. For this reason, we have used a geographic information system coupled to the multi-criteria analysis method AHP in order to evaluate diverse criteria of physiological positioning , environmental and economical. Another objective of this study is to evaluate the advanced techniques of the automatic learning . the method of the random forest (RF) for the patterning of the hospital site selection in the willaya of Oran. The result of our study may be useful to decision makers to know the suitability of the sites as it provides a high level of confidence and consequently accelerate the power to control the COVID19 pandemic.

scholarly journals The Ideal Microvascular Decompression Technique Should be Easy and Safe

2017 ◽  
Vol 3 (1) ◽  
pp. 1-3
Author(s):  
Jun Zhong ◽  
Shiting Li
Keyword(s):  
Microvascular Decompression ◽  
Nerve Root ◽  
Working Space ◽  
The World ◽  
Trigeminal Nerve Root ◽  
Intraoperative Electrophysiological Monitoring ◽  
Sharp Dissection ◽  
Functional Operation ◽  
Good Exposure ◽  
The Ideal

Microvascular decompression (MVD) surgery has been popularized as an etiological treatment around the world for more than half a century. However, as a functional operation in the cerebellopontine angle, this process should be refined to enhance cure and minimize complication. After accomplishing more than 10,000 MVDs, we have learned the following concerning the operative technique: (1) the principle of MVD is to separate the neurovascular confliction, rather than isolate with prostheses; (2) identification of the conflict relies on good exposure; (3) a satisfactory working space can be created by the appropriate positioning, i.e., either a close-to-the-sigmoid craniectomy or caudorostral approach; (4) a sharp dissection of arachnoids leads to a maximal visualization of the entire intracranial course of the nerve root; (5) all vessels contacting the trigeminal nerve root should be cleared off; (6) intraoperative electrophysiological monitoring may predict the prognosis of hemifacial spasm and guide the operation; and (7) the dura must be closed with watertight stitches at the end.

Small Scale Supercritical CO2 Radial Inflow Turbine Meanline Design Considerations

2018 ◽  
Author(s):  
Tina Unglaube ◽  
Hsiao-Wei D. Chiang
Keyword(s):  
High Velocity ◽  
Gas Turbines ◽  
Velocity Ratio ◽  
Maximum Efficiency ◽  
Design Parameters ◽  
Working Fluid ◽  
Small Scale ◽  
Optimum Velocity ◽  
Set Up ◽  
Very High

In recent years closed loop supercritical carbon dioxide Brayton cycles have drawn the attention of many researchers as they are characterized by a higher theoretic efficiency and smaller turbomachinery size compared to the conventional steam Rankine cycle for power generation. Currently, first prototypes of this emerging technology are under development and thus small scale sCO2 turbomachinery needs to be developed. However, the design of sCO2 turbines faces several new challenges, such as the very high rotational speed and the high power density. Thus, the eligibility of well-established radial inflow gas turbine design principles has to be reviewed regarding their suitability for sCO2 turbines. Therefore, this work reviews different suggestion for optimum velocity ratios for gas turbines and aims to re-establish it for sCO2 turbines. A mean line design procedure is developed to obtain the geometric dimensions for small scale sCO2 radial inflow turbines. By varying the specific speed and the velocity ratio, different turbine configurations are set up. They are compared numerically by means of CFD analysis to conclude on optimum design parameters with regard to maximum total-to-static efficiency. Six sets of simulations with different specific speeds between 0.15 and 0.52 are set up. Higher specific speeds could not be analyzed, as they require very high rotational speeds (more than 140k RPM) for small scale sCO2 turbines (up to 150kWe). For each set of simulations, the velocity ratio that effectuates maximum efficiency is identified and compared to the optimum parameters recommended for radial inflow turbines using subcritical air as the working fluid. It is found that the values for optimum velocity ratios suggested by Rohlik (1968) are rather far away from the optimum values indicated by the conducted simulations. However, the optimum values suggested by Aungier (2005), although also established for subcritical gas turbines, show an approximate agreement with the simulation results for sCO2 turbines. Though, this agreement should be studied for a wider range of specific speeds and a finer resolution of velocity ratios. Furthermore, for high specific speeds in combination with high velocity ratios, the pressure drop of the designed turbines is too high, so that the outlet pressure is beyond the critical point. For low specific speeds in combination with low velocity ratios, the power output of the designed turbines becomes very small. Geometrically, turbines with low specific speeds and high velocity ratios are characterized by very small blade heights, turbines with high specific speeds and small velocity ratios by very small diameters.

scholarly journals Flow regimes in a multi-gap circular Couette-Taylor system with opposite rotating cylinders

2021 ◽  
Vol 2119 (1) ◽  
pp. 012103
Author(s):  
A F Serov ◽  
V N Mamonov ◽  
A D Nazarov ◽  
N B Miskiv
Keyword(s):  
Flow Structure ◽  
Low Frequency ◽  
Working Fluid ◽  
Frequency Spectra ◽  
Initial Information ◽  
Heat Generator ◽  
Working Space ◽  
Resistance Torque ◽  
Hydrodynamic Processes ◽  
Circular Space

Abstract This work investigates the flow structure in the gaps of a multi-cylinder circular Couette-Taylor system, which is a model of a two-rotor heat generator. The initial information for studying the flow structure was data on the magnitude of the resistance torque to rotors opposed rotation, as well as on the nature of the amplitude-frequency spectrum of pulsations of this torque, depending on the viscosity of the working fluid and the rotational speed of the heat generator rotors. The obtained data allow comparing the nature of hydrodynamic processes in the single and obtained multi-gap circular space of Couette-Taylor and calculating the parameters of structural formations in the multi-gap working space of the heat generator. At relative rotational speeds of rotors (3-50) rad/s, the main energy of flow pulsations (up to 90%) is found in the amplitude-frequency spectra in the frequency range (12-70) Hz. It is associated with vortices first described by Taylor, which are extended low-frequency regularly alternating spirals and vortex structures with right and left rotation in the region of higher frequencies (200– 500) Hz; their frequency is determined by the width of the annular gaps of the multi-cylinder system.

MEASUREMENT OF FLOW IN CIRCULAR ELASTIC TUBE

2015 ◽  
Vol 76 (10) ◽  
Author(s):  
Muhamad Mazwan Mahat ◽  
Salmiah Kasolang ◽  
Izdihar Tharazi ◽  
R. Nazirul Izzati
Keyword(s):  
Structural Parameters ◽  
Circulatory System ◽  
Elastic Tube ◽  
Tube Length ◽  
Working Fluid ◽  
Circulatory Support ◽  
Pump System ◽  
Initial Work ◽  
Impedance Pump ◽  
Set Up

 Impedance pump is a simple valveless pumping mechanism which typically used in viscosity measurement device to assist pumping of fluid. It is typically connected to an elastic tube in a circulatory system of a more rigid tube. In conventional mechanical circulatory support systems using rotary pump, the pumping mechanism was exposed to turbulent stresses. Hence,  this may cause damage to blood cells flowing through the impeller. There has been initial work on finding alternative solution using the impedance pump system. However,  substantial findings are not yet sufficient to fully understand the mechanism. The purpose of this research is to extend the investigation on impedance pump by specifically looking at the effect of structural parameters on the elastic tube and the flow behaviour. In this study, a closed loop impedance pump system was set up to demonstrate blood flow circulatory system where the mixture of glycerine and water was used as the working fluid. Three variables were regulated namely voltage, tube thickness, and tube length was used in order to get the flowrate of the working fluid. Based on the results, it was found that  tube thickness of 1 mm and a length of 200 mm had produced the highest flowrate in the region 75 ml/min.

Enhancement of the Completion Efficiency of Perforation Tunnels in Petroleum Wells

2006 ◽  
Author(s):  
M. A. Rahman ◽  
T. Heidrick ◽  
B. Fleck ◽  
M. Koksal
Keyword(s):  
Fluid Flow ◽  
Conventional Method ◽  
Differential Pressure ◽  
Triaxial Testing ◽  
Flow Rates ◽  
Different Types ◽  
Set Up ◽  
Petroleum Wells ◽  
Perforated Completion ◽  
The Ideal

The objective of perforating is to maximize well productivity by establishing good connectivity between the wellbore and formation. The conventional method of perforation — perforation by shooting (PS) — cannot achieve expected wellbore productivity due to a region of reduced permeability around the perforation tunnel. In this study, it has been established that permeability is decreased in the range of 30%–75% due to the implementation of the PS technique compared to the openhole completion. As a result, a new perforation technique — perforation by drilling (PD) — has been proposed in this paper. To simulate a perforated completion, cylindrical sand samples (0.0572 in OD) consolidated with cement with varying porosity were prepared. These samples were perforated (0.0136 m ED) by the PS, PD and Casting techniques. Perforations created by the Casting techniques are considered the ideal, openhole perforation tunnel. Fluid flow rates and differential pressure across the perforated samples were measured for three different types of samples using “Geotechnical Digital System” triaxial testing set-up. Fluid flow rates with changing differential pressure and finally pressure build-up data with time indicates the PD technique can achieve better wellbore productivity compared to the PS technique. Results indicate that at 100 kPa differential pressure the PS, PD and Casting techniques can achieve 0.20 mL/s, 0.65 mL/s and 1.00 mL/s fluid flow rates respectively across a sample.

Simulation of Heat Flux Effect in Straight Heat Pipe as Passive Residual Heat Removal System in Light Water Reactor Using RELAP5 Mod 3.2

2016 ◽  
Vol 819 ◽  
pp. 122-126 ◽  
Author(s):  
M. Hadi Kusuma ◽  
Nandy Putra ◽  
Surip Widodo ◽  
Anhar Riza Antariksawan
Keyword(s):  
Heat Flux ◽  
Heat Pipe ◽  
Saturation Temperature ◽  
Heat Removal ◽  
Working Fluid ◽  
Steady State Condition ◽  
Set Up ◽  
Heat Removal System ◽  
Removal System ◽  
Residual Heat

Heat pipe is considered being used as a passive system to remove residual heat that generated from reactor core when incident occur or from spent fuel pool. The present research is aimed to studying the characteristics of straight heat pipe as passive residual heat removal system. As an initial step, a numerical simulation was conducted to simulate the best experimental design set up being prepared for the next step of the research. The objective is to get the thermal hydraulic characteristic due to variation of heat flux of heat source. The thermal hydraulic RELAP5 MOD 3.2 code is used to simulate and analyze the straight heat pipe characteristics. Variations of heat flux are 1567 Watt/m2, 3134 Watt/m2, 4701 Watt/m2, 6269 Watt/m2, and 7837 Watt/m2. Water as working fluid is heated on evaporation section with filling ratio 60%. Environmental air with variation 5 m/s and 10 m/s of velocity are used as external cooler. Straight heat pipe used in the simulation is wickless with 0.1 m of diameter and 6 m of length. The results show that higher heat flux given to the evaporator section will lead to more rapid heat transfer and achievement of steady state condition. The increasing of heat flux leads to an increase of evaporation of the working fluid and of pressure built in the heat pipe affecting higher saturation temperature of working fluid. Heat flux loading must consider the velocity of air as heat removal in the condenser to prevent dry out phenomenon in the evaporator. Based on the results, given the experimental set-up, the optimum range of experimental parameters could be determined.

Sign in / Sign up

Export Citation Format

Share Document