Calorimetric efficiency determination of power electronic variable speed drives

A calorimeter test bench for the efficiency and power loss determination of power electronic variable speed drives is presented. The balanced calorimetric setup with air as the cooling medium is proposed to test small electronic drives for AC motors in a power range from 1 kW up to 7,5 kW. The construction, the required measurement equipment, the measurement procedure and especially the measurement results and uncertainty are important aspects of this test bench and are discussed in this paper. The device under test is a 2,2kW drive which is measured using both the input-output method and the calorimetric method. The test results are compared and conclusions are made concerning usability, repeatability and accuracy of the test bench. The overall goal is to further examine and optimize the calorimetric approach and to be able to obtain more accurate and comparable test results of very high efficient frequency converters. This setup reaches an uncertainty of ±2,39% or ±1,48W on the power loss at full load and speed using the calorimetric method

Torque measurement on wind turbines and its application in the determination of drivetrain efficiency

The input torque of a wind turbine contains an abundance of information about the operating conditions of the turbine. At the same time it is also a critical input for the efficiency determination of the drivetrain. An appropriate method of torque measurement plays an important role in wind turbines research and helps to further reduce the COE (cost of energy) of the wind turbines. However, a number of challenges are currently restricting the breadth and depth of torque measurement applications in the testing and operation of wind turbines. The research described in this dissertation studies the major challenges posed by the different aspects of torque measurement, including the measuring principle, the calibration and the uncertainty. The efficiency determination of the drivetrain is also studied as an important application, which has the highest demand on the accuracy of torque measurement and its calibration among applications in the wind energy industry. The research proposes new approaches and improvements to cope with the above mentioned challenges. A new method of torque measurement based on the rotary encoders is proposed and realised during a test campaign. During the same test campaign, improvement of the traditional torque measurement based on strain gauges is also demonstrated, where the influence of non-torque loads is greatly reduced by having more measuring points for the torque measurement. A new method is also proposed to address the problem of insufficient accuracy in the drivetrain efficiency determination of a wind turbine on the test bench. With the proposed method, the dependency of the determined efficiency on the accuracy of torque and electrical power measurement can be effectively reduced. As a result, the efficiency can be determined with an uncertainty considerably lower than that of the torque measurement. The method takes advantage of a specially designed test sequence whereby the test bench and the wind turbine drivetrain take turns to run in motor mode and drive the other one which operates in generator mode. The same test sequence is also adopted to develop a method of torque calibration. The method establishes a relationship between the torque and the electrical power using measurements from the two tests where the turbine drivetrain operates in different modes. The calibration uncertainty introduced by the power loss in the drivetrain is thus reduced. Detailed uncertainty analysis for the efficiency determination and torque calibration is carried out in this research to confirm the benefit as well as quantify the effectiveness of the methods proposed. Future work and further applications of the methods proposed are presented at the end of the dissertation

Assessment of induction machine efficiency with comments on new standard IEC 60034-2-1

The paper assesses the efficiency of induction machines and measurement uncertainties arising from various input-output testing methods used in industry. Existing testing standards vary in methodology, procedure and required instrumentation accuracy, thus leading to significant differences in the experimentally determined efficiency for the same induction machine tested to the different standards as well as by different testing personnel. This paper focuses on the recently published IEC standard 60034-2-1, with comparisons of its previous version (IEC 34-2), and IEEE 112-B. Five induction machines with ratings between 7.5 and 150 kW are carefully tested using these methods and power loss results are validated by a separate calorimeter. Through theoretical analysis of measurement uncertainty using realistic perturbation-based estimation (RPBE) on these results, IEC 60034-2-1 is assessed in terms of its effectiveness and improvements over its previous version. Attention is paid particularly to these factors significantly impacting the machine efficiency such as determinations of stray load losses (SLL), stator winding resistance, stator winding temperature, and detailed specifications of testing procedures

Planetary explorer liquid propulsion study

An analytical evaluation of several candidate monopropellant hydrazine propulsion system approaches is conducted in order to define the most suitable configuration for the combined velocity and attitude control system for the Planetary Explorer spacecraft. Both orbiter and probe-type missions to the planet Venus are considered. The spacecraft concept is that of a Delta launched spin-stabilized vehicle. Velocity control is obtained through preprogrammed pulse-mode firing of the thrusters in synchronism with the spacecraft spin rate. Configuration selection is found to be strongly influenced by the possible error torques induced by uncertainties in thruster operation and installation. The propulsion systems defined are based on maximum use of existing, qualified components. Ground support equipment requirements are defined and system development testing outlined

A good practice guide on the sources and magnitude of uncertainty arising in the practical measurement of environmental noise

A brief introduction to measurement uncertainty, uncertainty budgets, and inter-comparison exercises (repeated measurements), is provided in Chapter 2. The procedure forformulating an uncertainty budget and evaluating magnitudes is outlined in greater detail in Chapter 3. A flow chart summarising this process, and a checklist for the identification of sources of measurement uncertainty are included at the end of the chapter. Two example measurement exercises with corresponding uncertainty budgets are presented in Chapter 4. Some of the more commonly encountered sources of measurement uncertainty are outlined in Chapter5. Where possible, information on magnitudes or pointers to where that information can be found are included. The more important sources of uncertainty are highlighted, and “good practice guidelines” provided to help the practitioner identify means of reducing their effect. Case studies illustrating some of the points made in Chapter 5,and listing of relevant guidelines and further reading are provided in the Appendices

Studies of the exhaust products from solid propellant rocket motors

This study was undertaken to determine the feasibility of conducting environmental chamber tests on the physical processes which occur when a solid rocket motor exhaust mixes with the ambient atmosphere. Of particular interest was the interaction between hydrogen chloride, aluminum oxide, and water vapor. The program consisted of three phases: (1) building a small rocket motor and using it to provide the exhaust species in a controlled environment; (2) evaluating instruments used to detect and measure HCl concentrations and if possible determining whether the HCl existed in the gaseous state or as an acid aerosol; (3) monitoring a series of 6.4-percent scale space shuttle motor tests and comparing the results to the environmental chamber studies. Eighteen firings were conducted in an environmental chamber with the initial ambient relative humidity set at values from 29 to 100 percent. Two additional firings were made in a large shed, and four were made on an open concrete apron. Six test firings at MSFC were monitored, and the ground level concentrations are reported. Evidence is presented which shows that the larger Al2O3 (5 to 50 micrometers) particles from the rocket motor can act as condensation nuclei. Under appropriate ambient conditions where there is sufficient water vapor this results in the formation of an acid aerosol. Droplets of this acid were detected both in the environmental chamber and in the scaled shuttle engine tests

Determination of urban volatile organic compound emission ratios and comparison with an emissions database

During the NEAQS-ITCT2k4 campaign in New England, anthropogenic VOCs and CO were measured downwind from New York City and Boston. The emission ratios of VOCs relative to CO and acetylene were calculated using a method in which the ratio of a VOC with acetylene is plotted versus the photochemical age. The intercept at the photochemical age of zero gives the emission ratio. The so determined emission ratios were compared to other measurement sets, including data from the same location in 2002, canister samples collected inside New York City and Boston, aircraft measurements from Los Angeles in 2002, and the average urban composition of 39 U.S. cities. All the measurements generally agree within a factor of two. The measured emission ratios also agree for most compounds within a factor of two with vehicle exhaust data indicating that a major source of VOCs in urban areas is automobiles. A comparison with an anthropogenic emission database shows less agreement. Especially large discrepancies were found for the C2-C4 alkanes and most oxygenated species. As an example, the database overestimated toluene by almost a factor of three, which caused an air quality forecast model (WRF-CHEM) using this database to overpredict the toluene mixing ratio by a factor of 2.5 as well. On the other hand, the overall reactivity of the measured species and the reactivity of the same compounds in the emission database were found to agree within 30%. Copyright 2007 by the American Geophysical Union

The Focal plane Detector Package on the TUNL Split-pole Spectrograph

A focal plane detector for the Enge Split-pole Spectrograph at Triangle Universities Nuclear Laboratory has been designed. The detector package consists of two position sensitive gas avalanche counters, a gas proportionality energy loss section, and a residual energy scintillator. This setup allows both particle identification and focal plane reconstruction. In this paper we will detail the construction of each section along with their accompanying electronics and data acquisition. Effects of energy loss throughout the detector, ray tracing procedures, and resolution as a function of fill pressure and bias voltage are also investigated. A measurement of the $^{27}\!$Al$(d,p)$ reaction is used to demonstrate detector performance and to illustrate a Bayesian method of energy calibration