SI Derived Units
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Che 253M Experiment No. 2 COMPRESSIBLE GAS FLOW
Rev. 8/15 AD/GW ChE 253M Experiment No. 2 COMPRESSIBLE GAS FLOW The objective of this experiment is to familiarize the student with methods for measurement of compressible gas flow and to study gas flow under subsonic and supersonic flow conditions. The experiment is divided into three distinct parts: (1) Calibration and determination of the critical pressure ratio for a critical flow nozzle under supersonic flow conditions (2) Calculation of the discharge coefficient and Reynolds number for an orifice under subsonic (non- choked) flow conditions and (3) Determination of the orifice constants and mass discharge from a pressurized tank in a dynamic bleed down experiment under (choked) flow conditions. The experimental set up consists of a 100 psig air source branched into two manifolds: the first used for parts (1) and (2) and the second for part (3). The first manifold contains a critical flow nozzle, a NIST-calibrated in-line digital mass flow meter, and an orifice meter, all connected in series with copper piping. The second manifold contains a strain-gauge pressure transducer and a stainless steel tank, which can be pressurized and subsequently bled via a number of attached orifices. A number of NIST-calibrated digital hand held manometers are also used for measuring pressure in all 3 parts of this experiment. Assorted pressure regulators, manual valves, and pressure gauges are present on both manifolds and you are expected to familiarize yourself with the process flow, and know how to operate them to carry out the experiment. A process flow diagram plus handouts outlining the theory of operation of these devices are attached. -
Appendix A: Symbols and Prefixes
Appendix A: Symbols and Prefixes (Appendix A last revised November 2020) This appendix of the Author's Kit provides recommendations on prefixes, unit symbols and abbreviations, and factors for conversion into units of the International System. Prefixes Recommended prefixes indicating decimal multiples or submultiples of units and their symbols are as follows: Multiple Prefix Abbreviation 1024 yotta Y 1021 zetta Z 1018 exa E 1015 peta P 1012 tera T 109 giga G 106 mega M 103 kilo k 102 hecto h 10 deka da 10-1 deci d 10-2 centi c 10-3 milli m 10-6 micro μ 10-9 nano n 10-12 pico p 10-15 femto f 10-18 atto a 10-21 zepto z 10-24 yocto y Avoid using compound prefixes, such as micromicro for pico and kilomega for giga. The abbreviation of a prefix is considered to be combined with the abbreviation/symbol to which it is directly attached, forming with it a new unit symbol, which can be raised to a positive or negative power and which can be combined with other unit abbreviations/symbols to form abbreviations/symbols for compound units. For example: 1 cm3 = (10-2 m)3 = 10-6 m3 1 μs-1 = (10-6 s)-1 = 106 s-1 1 mm2/s = (10-3 m)2/s = 10-6 m2/s Abbreviations and Symbols Whenever possible, avoid using abbreviations and symbols in paragraph text; however, when it is deemed necessary to use such, define all but the most common at first use. The following is a recommended list of abbreviations/symbols for some important units. -
Application Note AN-1057
Application Note AN-1057 Heatsink Characteristics Table of Contents Page Introduction.........................................................................................................1 Maximization of Thermal Management .............................................................1 Heat Transfer Basics ..........................................................................................1 Terms and Definitions ........................................................................................2 Modes of Heat Transfer ......................................................................................2 Conduction..........................................................................................................2 Convection ..........................................................................................................5 Radiation .............................................................................................................9 Removing Heat from a Semiconductor...........................................................11 Selecting the Correct Heatsink........................................................................11 In many electronic applications, temperature becomes an important factor when designing a system. Switching and conduction losses can heat up the silicon of the device above its maximum Junction Temperature (Tjmax) and cause performance failure, breakdown and worst case, fire. Therefore the temperature of the device must be calculated not to exceed the Tjmax. To design a good -
A Review of Energy Storage Technologies' Application
sustainability Review A Review of Energy Storage Technologies’ Application Potentials in Renewable Energy Sources Grid Integration Henok Ayele Behabtu 1,2,* , Maarten Messagie 1, Thierry Coosemans 1, Maitane Berecibar 1, Kinde Anlay Fante 2 , Abraham Alem Kebede 1,2 and Joeri Van Mierlo 1 1 Mobility, Logistics, and Automotive Technology Research Centre, Vrije Universiteit Brussels, Pleinlaan 2, 1050 Brussels, Belgium; [email protected] (M.M.); [email protected] (T.C.); [email protected] (M.B.); [email protected] (A.A.K.); [email protected] (J.V.M.) 2 Faculty of Electrical and Computer Engineering, Jimma Institute of Technology, Jimma University, Jimma P.O. Box 378, Ethiopia; [email protected] * Correspondence: [email protected]; Tel.: +32-485659951 or +251-926434658 Received: 12 November 2020; Accepted: 11 December 2020; Published: 15 December 2020 Abstract: Renewable energy sources (RESs) such as wind and solar are frequently hit by fluctuations due to, for example, insufficient wind or sunshine. Energy storage technologies (ESTs) mitigate the problem by storing excess energy generated and then making it accessible on demand. While there are various EST studies, the literature remains isolated and dated. The comparison of the characteristics of ESTs and their potential applications is also short. This paper fills this gap. Using selected criteria, it identifies key ESTs and provides an updated review of the literature on ESTs and their application potential to the renewable energy sector. The critical review shows a high potential application for Li-ion batteries and most fit to mitigate the fluctuation of RESs in utility grid integration sector. -
Far Infrared Radiation Exposure
INTERNATIONAL COMMISSION ON NON‐IONIZING RADIATION PROTECTION ICNIRP STATEMENT ON FAR INFRARED RADIATION EXPOSURE PUBLISHED IN: HEALTH PHYSICS 91(6):630‐645; 2006 ICNIRP PUBLICATION – 2006 ICNIRP Statement ICNIRP STATEMENT ON FAR INFRARED RADIATION EXPOSURE The International Commission on Non-Ionizing Radiation Protection* INTRODUCTION the health hazards associated with these hot environ- ments. Heat strain and discomfort (thermal pain) nor- THE INTERNATIONAL Commission on Non Ionizing Radia- mally limit skin exposure to infrared radiation levels tion Protection (ICNIRP) currently provides guidelines below the threshold for skin-thermal injury, and this is to limit human exposure to intense, broadband infrared particularly true for sources that emit largely IR-C. radiation (ICNIRP 1997). The guidelines that pertained Furthermore, limits for lengthy infrared exposures would to infrared radiation (IR) were developed initially with an have to consider ambient temperatures. For example, an aim to provide guidance for protecting against hazards infrared irradiance of 1 kW mϪ2 (100 mW cmϪ2)atan from high-intensity artificial sources and to protect work- ambient temperature of 5°C can be comfortably warm- ers in hot industries. Detailed guidance for exposure to ing, but at an ambient temperature of 30°C this irradiance longer far-infrared wavelengths (referred to as IR-C would be painful and produce severe heat strain. There- radiation) was not provided because the energy at longer fore, ICNIRP provided guidelines to limit skin exposure wavelengths from most lamps and industrial infrared to pulsed sources and very brief exposures where thermal sources of concern actually contribute only a small injury could take place faster than the pain response time fraction of the total radiant heat energy and did not and where environmental temperature and the irradiated require measurement. -
Aspects of Flow for Current, Flow Rate Is Directly Proportional to Potential
Vacuum technology Aspects of flow For current, flow rate is directly proportional to potential difference and inversely proportional to resistance. I = V/R or I = V/R For a fluid flow, Q = (P1-P2)/R or P/R Using reciprocal of resistance, called conductance, we have, Q = C (P1-P2) There are two kinds of flow, volumetric flow and mass flow Volume flow rate, S = vA v – the average bulk velocity, A the cross sectional area S = V/t, V is the volume and t is the time. Mass flow rate is S x density. G = vA or V/t Mass flow rate is measured in units of throughput, such as torr.L/s Throughput = volume flow rate x pressure Throughput is equivalent to power. Torr.L/s (g/cm2)cm3/s g.cm/s J/s W It works out that, 1W = 7.5 torr.L/s Types of low 1. Laminar: Occurs when the ratio of mass flow to viscosity (Reynolds number) is low for a given diameter. This happens when Reynolds number is approximately below 2000. Q ~ P12-P22 2. Above 3000, flow becomes turbulent Q ~ (P12-P22)0.5 3. Choked flow occurs when there is a flow restriction between two pressure regions. Assume an orifice and the pressure difference between the two sections, such as 2:1. Assume that the pressure in the inlet chamber is constant. The flow relation is, Q ~ P1 4. Molecular flow: When pressure reduces, MFP becomes larger than the dimensions of the duct, collisions occur between the walls of the vessel. -
How Air Velocity Affects the Thermal Performance of Heat Sinks: a Comparison of Straight Fin, Pin Fin and Maxiflowtm Architectures
How Air Velocity Affects The Thermal Performance of Heat Sinks: A Comparison of Straight Fin, Pin Fin and maxiFLOWTM Architectures Introduction A device’s temperature affects its op- erational performance and lifetime. To Air, Ta achieve a desired device temperature, Heat sink the heat dissipated by the device must be transferred along some path to the Rhs environment [1]. The most common method for transferring this heat is by finned metal devices, otherwise known Rsp as heat sinks. Base Resistance to heat transfer is called TIM thermal resistance. The thermal resis- RTIM tance of a heat sink decreases with . Component case, Tc Q Component more heat transfer area. However, be- cause device and equipment sizes are decreasing, heat sink sizes are also Figure 1. Exploded View of a Straight Fin Heat Sink with Corresponding Thermal Resis- tance Diagram. growing smaller. On the other hand, . device heat dissipation is increasing. heat sink selection criteria. Q RTIM, as shown in Equation 2. Therefore, designing a heat transfer The heat transfer rate of a heat sink, , . path in a limited space that minimizes depends on the difference between the Q = (Thot - Tcold)/Rt = (Tc - Ta)/Rt (1) thermal resistance is critical to the ef- component case temperature, Tc, and fective design of electronic equipment. the air temperature, Ta, along with the where total thermal resistance, Rt. This rela- This article discusses the effects of air tionship is shown in Equation 1. For Rt = RTIM + Rsp + Rhs (2) flow velocity on the experimentally de- a basic heat sink design, as shown in termined thermal resistance of different Figure 1, the total thermal resistance Therefore, to compare different heat heat sink designs. -
University Physics 227N/232N Ch 27
Vector pointing OUT of page University Physics 227N/232N Ch 27: Inductors, towards Ch 28: AC Circuits Quiz and Homework This Week Dr. Todd Satogata (ODU/Jefferson Lab) [email protected] http://www.toddsatogata.net/2014-ODU Monday, March 31 2014 Happy Birthday to Jack Antonoff, Kate Micucci, Ewan McGregor, Christopher Walken, Carlo Rubbia (1984 Nobel), and Al Gore (2007 Nobel) (and Sin-Itiro Tomonaga and Rene Descartes and Johann Sebastian Bach too!) Prof. Satogata / Spring 2014 ODU University Physics 227N/232N 1 Testing for Rest of Semester § Past Exams § Full solutions promptly posted for review (done) § Quizzes § Similar to (but not exactly the same as) homework § Full solutions promptly posted for review § Future Exams (including comprehensive final) § I’ll provide copy of cheat sheet(s) at least one week in advance § Still no computer/cell phone/interwebz/Chegg/call-a-friend § Will only be homework/quiz/exam problems you have seen! • So no separate practice exam (you’ll have seen them all anyway) § Extra incentive to do/review/work through/understand homework § Reduces (some) of the panic of the (omg) comprehensive exam • But still tests your comprehensive knowledge of what we’ve done Prof. Satogata / Spring 2014 ODU University Physics 227N/232N 2 Review: Magnetism § Magnetism exerts a force on moving electric charges F~ = q~v B~ magnitude F = qvB sin ✓ § Direction follows⇥ right hand rule, perpendicular to both ~v and B~ § Be careful about the sign of the charge q § Magnetic fields also originate from moving electric charges § Electric currents create magnetic fields! § There are no individual magnetic “charges” § Magnetic field lines are always closed loops § Biot-Savart law: how a current creates a magnetic field: µ0 IdL~ rˆ 7 dB~ = ⇥ µ0 4⇡ 10− T m/A 4⇡ r2 ⌘ ⇥ − § Magnetic field field from an infinitely long line of current I § Field lines are right-hand circles around the line of current § Each field line has a constant magnetic field of µ I B = 0 2⇡r Prof. -
Accelerometers Used in the Measurement of Jerk, Snap, and Crackle
Accelerometers used in the measurement of jerk, snap, and crackle David Eager Faculty of Engineering and IT, University of Technology Sydney, PO Box 123 Broadway, Australia ABSTRACT Accelerometers are traditionally used in acoustics for the measurement of vibration. Higher derivatives of motion are rarely considered when measuring vibration. This paper presents a novel usage of a triaxial accelerometer to measure acceleration and use these data to explain jerk and higher derivatives of motion. We are all familiar with the terms displacement, velocity and acceleration but few of us are familiar with the term jerk and even fewer of us are familiar with the terms snap and crackle. We experience velocity when we are displaced with respect to time and acceleration when we change our velocity. We do not feel velocity, but rather the change of velocity i.e. acceleration which is brought about by the force exerted on our body. Similarly, we feel jerk and higher derivatives when the force on our body experiences changes abruptly with respect to time. The results from a gymnastic trampolinist where the acceleration data were collected at 100 Hz using a device attached to the chest are pre- sented and discussed. In particular the higher derivates of the Force total eQuation are extended and discussed, 3 3 4 4 5 5 namely: ijerk∙d x/dt , rsnap∙d x/dt , ncrackle∙d x/dt etc. 1 INTRODUCTION We are exposed to a wide variety of external motion and movement on a daily basis. From driving a car to catching an elevator, our bodies are repeatedly exposed to external forces acting upon us, leading to acceleration. -
AN00118-000 Motion Profiles.Doc
A N00118-000 - Motion Profiles Related Applications or Terminology Supported Controllers ■ Trapezoidal Velocity Profile NextMovePCI NextMoveBXII ■ S-Ramped Velocity Profile NextMoveST NextMoveES Overview MintDriveII The motion of moving objects can be specified by a number of Flex+DriveII parameters, which together define the Motion Profile. These parameters are: Relevant Keywords Speed: The rate of change of position PROFILEMODE Acceleration: The rate of change of speed during an SPEED ACCEL increase of speed. DECEL Deceleration: The rate of change of speed during a ACCELJERK decrease of speed. DECELJERK Jerk: The rate of change of acceleration or deceleration. Trapezoidal Profile A trapezoidal profile is typically made up of three sections, an acceleration phase, a constant velocity phase and a deceleration phase. Velocity Time Acceleration Constant Velocity Deceleration © Baldor UK Ltd 2003 1 of 6 AN00118-000 Motion Profiles.doc The graph is a plot of velocity against time for a trapezoidal profile; the name reflects the shape of the profile. For a positional move from rest, the velocity increases at the rate defined by acceleration until it reaches the slew speed. The velocity will then remain constant until the deceleration point, where the velocity will then decrease to a halt at the rate specified by deceleration. S-Ramped Profile An s-ramped profile can be considered as a super set of the trapezoidal profile. It typically is made up of seven sections, four jerk phases on top of the acceleration phase, constant velocity phase and deceleration phase. Velocity Time Acceleration Constant Velocity Deceleration The graph is a plot of velocity against time for an s-curve profile; again the name reflects the shape of the profile. -
An Evaluation of Turbocharging and Supercharging Options for High-Efficiency Fuel Cell Electric Vehicles
applied sciences Article An Evaluation of Turbocharging and Supercharging Options for High-Efficiency Fuel Cell Electric Vehicles Arthur Kerviel 1,2, Apostolos Pesyridis 1,* , Ahmed Mohammed 1 and David Chalet 2 1 Department of Mechanical and Aerospace Engineering, Brunel University, London UB8 3PH, UK; [email protected] (A.K.); [email protected] (A.M.) 2 Ecole Centrale de Nantes, LHEEA Lab. (ECN/CNRS), 44321 Nantes, France; [email protected] * Correspondence: [email protected]; Tel.: +44-189-526-7901 Received: 17 October 2018; Accepted: 19 November 2018; Published: 3 December 2018 Abstract: Mass-produced, off-the-shelf automotive air compressors cannot be directly used for boosting a fuel cell vehicle (FCV) application in the same way that they are used in internal combustion engines, since the requirements are different. These include a high pressure ratio, a low mass flow rate, a high efficiency requirement, and a compact size. From the established fuel cell types, the most promising for application in passenger cars or light commercial vehicle applications is the proton exchange membrane fuel cell (PEMFC), operating at around 80 ◦C. In this case, an electric-assisted turbocharger (E-turbocharger) and electric supercharger (single or two-stage) are more suitable than screw and scroll compressors. In order to determine which type of these boosting options is the most suitable for FCV application and assess their individual merits, a co-simulation of FCV powertrains between GT-SUITE and MATLAB/SIMULINK is realised to compare vehicle performance on the Worldwide Harmonised Light Vehicle Test Procedure (WLTP) driving cycle. -
Photometric Calibrations —————————————————————————
NIST Special Publication 250-37 NIST MEASUREMENT SERVICES: PHOTOMETRIC CALIBRATIONS ————————————————————————— Yoshihiro Ohno Optical Technology Division Physics Laboratory National Institute of Standards and Technology Gaithersburg, MD 20899 Supersedes SP250-15 Reprint with changes July 1997 ————————————————————————— U.S. DEPARTMENT OF COMMERCE William M. Daley, Secretary Technology Administration Gary R. Bachula, Acting Under Secretary for Technology National Institute of Standards and Technology Robert E. Hebner, Acting Director PREFACE The calibration and related measurement services of the National Institute of Standards and Technology are intended to assist the makers and users of precision measuring instruments in achieving the highest possible levels of accuracy, quality, and productivity. NIST offers over 300 different calibrations, special tests, and measurement assurance services. These services allow customers to directly link their measurement systems to measurement systems and standards maintained by NIST. These services are offered to the public and private organizations alike. They are described in NIST Special Publication (SP) 250, NIST Calibration Services Users Guide. The Users Guide is supplemented by a number of Special Publications (designated as the “SP250 Series”) that provide detailed descriptions of the important features of specific NIST calibration services. These documents provide a description of the: (1) specifications for the services; (2) design philosophy and theory; (3) NIST measurement system; (4) NIST operational procedures; (5) assessment of the measurement uncertainty including random and systematic errors and an error budget; and (6) internal quality control procedures used by NIST. These documents will present more detail than can be given in NIST calibration reports, or than is generally allowed in articles in scientific journals. In the past, NIST has published such information in a variety of ways.