Calibration-Free Volume Flow Measurement Principle Based on Thermal Time-of-Flight (TToF)

Thermal flow measurement is currently based on the principle of heat energy displacement caused by a flowing fluid (mass flow measurement). The heat is induced by a continuous heating element immersed into the fluid. This kind of sensor is only applicable for fluids with known homogeneity properties [3].

Thermal signal behaviour for air flow measurements as fundamentals to Time-of-Flight

Many household appliances are equipped with inverter technology which may generate disturbances in the frequency range 9 kHz to 150 kHz. Since the standards managing the disturbance in this frequency range are not covering all household appliances, the effort to limit the disturbance produced by some appliances become less. The disturbance produced by the appliance may influence the operation performance of neighbor appliances which are connected to the same network. In the other hand, the neighbor appliances due to their internal properties may also influence the disturbance produced by the appliance. Some phenomena regarding the interaction of disturbance characteristics between appliances have been recognized and reported by some researchers, but no further analysis can be done due to the limited knowledge about this disturbance characteristics. 
The study focuses on observing the properties and behavior of disturbances in the frequency range 9 kHz to 150 kHz produced by some household appliances in a residential network environment. The disturbance properties and behavior are important to predict and investigate the disturbance occurred in the network. The effect of some parameters of residential network environment to the disturbances are observed including the variation of mains voltage level, the presence of neighbor appliances and the variation of mains network impedance. There are four main works conducted in this study, the first is identifying the internal impedance properties of appliances, the second is defining the disturbance properties and behavior for individual and simultaneous operation of appliances, the third is simulating the disturbance for simultaneous operation of appliances in residential network environment, and the last is reviewing the existing standards of disturbance in the frequency range 9 kHz to 150 kHz corresponding to the real residential network situations. The equipment under test used in this study are induction cooker, inverter microwave, conventional microwave, mixer, hand blender, water cooker, personal computer, notebook, television LED, hair dryer, electric massage, iron, compact fluorescent lamp and LED lamp. 
The disturbance emitted by each household appliance in the frequency range 9 kHz to 150 kHz has unique properties and behavior. The disturbance is affected by the presence of neighbor appliance in the network. The neighbor appliances, depending on their power consumption and internal impedance properties, may increase or decrease the disturbance occurred in the network. Besides, the mains voltage level and the mains network impedance variation are also influencing the disturbance. Some conditions in the real residential network environment may lead to the difference of disturbance obtained in the standard emission test and the real network environment. The user should be aware that there are situations in which the emission occurred in the field could be different.

The properties and behavior of disturbances in the frequency range 9 kHz to 150 kHz produced by household appliances in a residential network environment

A system-theoretical model of an air flow sensor based on the principle of pulsed thermal Time-of-Flight (TTOF) is described. The region of interest (ROI) in the pipe flow is regarded as a linear time-invariant (LTI) system with an input and output signal. Based on the experimental results the simulation model is created and applied for analysis of different input signals and system's responses with respect to the flow velocity. Experimental and simulated results are compared in an air flow velocity range between 0.1 m/s and 0.7 m/s.

System-theoretical analysis and modeling of pulsed thermal Time-of-Flight flow sensor

A premixed mixture for a combustion process is said to be stoichiometric when the amount of air provided is just enough to burn the fuel completely. A parameter called the equivalence ratio gives a measure of the closeness of the combustion system to stoichiometric combustion. In practice, excess air is provided in a combustion system to avoid production of harmful flue gases. The amount of fuel and air intake in a combustion process along with their degree of mixing affects its efficiency. This thesis describes the design of a mass airflow sensor and a flame temperature sensor that can be used to estimate mass airflow rate and equivalence ratio respectively, thereby enabling control of the efficiency of combustion systems. The mass airflow sensor designed for this thesis is an inline airflow sensor that can be used to measure combustion intake air in the temperature range between -40◦F to 140◦F and mass airflow rate between 0 kg/hr to 120 kg/hr. The mass airflow sensor is based on the principle of constant temperature difference thermal mass airflow meter. Thermistors are used as resistive elements for the mass airflow meter discussed in this thesis. The sensor was calibrated considering the wide range of operation of temperature; and mechanical and electrical tolerance of thermistors used in the sensor. The performance of the sensor with disturbances in combustion air intake

Mass Airflow Sensor and Flame Temperature Sensor for Efficiency Control of Combustion Systems

This communication reports on a numeric fluid dynamics simulation on a pipe flow model. The basic background is to deter- mine the velocity of a flowing fluid in a pipe by using the Thermal Time-of-Flight (TTOF) method on water. The visualisation of the temperature and velocity distribution in the pipe model is being carried out in order to enable proper design and optimisation of the TTOF sensor. The work is accomplished in two dimensional and three dimensional simulations. Transient simulations have been realised using the 2D simulation model. The flow velocity is calculated by means of the FFT-correlation technique. At several detection points the time- dependent temperarure signal is measured in a time period of ten seconds. The time delay of the output signals combined with the knowledge of the covered distances yields the flow velocity. In this work, a flow measurement technique in the velocity range 0.01 m/s ≤ vm ≤ 0.1 m/s is presented for water.

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Modelling Thermal Time-of-Flight Sensor for Flow Velocity Measurement

Some smart meters use G3 PLC in a frequency range of 150 kHz to 500 kHz to communicate with the utilities. This paper investigates whether G3 PLC signals are able to disturb the metrology or the communication of meters. For testing, the G3 signals are simulated by band limited noise and by an OFDM signal. Puls modulated and unmodulated signals are tested. The tests are based on IEC CDV 61000-4-3 [1].

Investigation of smart meters using G3 PLC

Some smart meters use Power Line Communication (PLC) to communicate with the utilities. This paper investigates whether common PLC signals are able to disturb the metrology part. For testing, the signals are simulated by band limited noise and by an OFDM signal. Puls modulated and unmodulated signals are tested. The tests are based on IEC FDIS 61000-4-31 [1].

Immunity of smart meters against Communication signals

In their normal operating environment, high voltage devices often are exposed to voltage forms that differ from the main intended voltage forms. For most high voltage devices this natural operating environment is the power grid. One group of possible voltages to occur in this environment are the so called impulse voltages, very short high voltage pulses with very high energy content. Some are caused internally (switching operations inside the grid), some are of external cause (lightning strokes). In most cases these impulse voltages are superimposed to the actual operating voltage and have amplitudes well beyond the actual operating voltage. For the high voltage devices to be able to withstand these impulse voltages, standards like the IEC 60060series describe the exact procedures for testing high voltage devices with impulse voltages already during their design phase or before going into operation. Within these standards, many forms of impulse voltages are defined: lightning impulses, switching impulses, front chopped lightning impulses, tail chopped lightning impulses to name only a few. Generating and measuring these voltages, often a few Megavolts in amplitude, is technically challenging. Evaluating the form of these impulse voltages and assuring that the impulses to meet the requirements stipulated in the standards is another challenge of its own. Today, even normal PCs offer extremely high computational power and vast amounts of memory. Combining these with digital PC oscilloscopes with custom APIs makes the development of such an impulse voltage analysis system comparatively easy and cheap. In addition to the new system's hardware, a new software, fulfilling the new 2013 IEC 61083-2's [2] requirements has been developed. This paper will show insights into the development of the impulse voltage analysis system at the University of Duisburg-Essen's high voltage laboratory.

M. Malek

Papers

Modelling Thermal Time-of-Flight Sensor for Flow Velocity Measurement

Thermal signal behaviour for air flow measurements as fundamentals to Time-of-Flight

Investigation of smart meters using G3 PLC

Immunity of smart meters against Communication signals

Development of a flexible high resolution high voltage impulse voltage analysis system