Sensor systems flow measurements

In Fig. 6.1, an attempt is made to show to what extent sensors have been penetrating the appliance market over the past years, a trend which is set to continue in the next decade. In the beginning, there were relatively simple sensors for temperature, pressure, flow, etc. Over the last years, non-contact measuring devices have attracted much attention, such as non-contact temperature monitoring for toasters or for hair blowers. The introduction of more complex sensor systems, such as water quality sensors or multi gas sensing artificial noses is imminent. 

The most important sensors for control of the drying process are those for inlet-air and exhaust-air temperature and the sensor for air flow measurement, located in the ah transport system. Other sensors for the spray agglomeration process include those for atomization air pressure and volume, pressure drops (across... 

One class of flow measurement which is becoming of increasing importance (particularly in the form of sensors for control systems) is the monitoring of mass flow. This is rapidly superseding the measurement of volumetric flow—especially where it is required to determine accurately the transfer of large quantities of gas and liquid in the oil, gas and water industries. Two principal approaches are employed to measure mass flow. One is indirect and uses a combination of volumetric flow and density and the other is direct in that it involves the measurement of properties which are sensitive to variations in the mass rate of flow itself. 

A mixer, which is part of a sensor system, has diagonal grooves on the channel bottom [142], This creates a lateral flow enlarging the interfacial area. No indication is given whether this measure causes the flow to become chaotic. 

The electronic control circuitry is situated in two levels below the MCB layer with the modules. It is based on a microcontroller system for the micro liquid handling and the chemical analysis data. Implemented in the electrical circuitry are driving circuits for the micro pumps, sensing circuits for the flow sensors, optical absorption measurement circuitry, power management and communications using an RS232 interface. 

An alarm should sound any time redundant inputs disagree. In most cases, the operating personnel will have to decide what to do. In some cases the computer control system will have to decide by itself what to do if redundant inputs disagree. The more hazardous the process, the more it is necessary to use multiple sensors for flow, temperature, pressure, and other variables. Since it must be assumed that all measuring devices will fail, they should fail to an alarm state. If a device fails to a nonalarm condition, there can be serious problems. It is also serious if a device fails to an alarm condition, and there is really not an alarm condition. This is generally not as serious as the first case, but it can provide a false sense of security. Usually it is assumed that two... 

From the frequency measurement for different concentrations of organic substance contained in air, it is shown that the sensor can detect the concentration of different sizes of organic materials. A good recovery of the sensor to the initial condition is shown, and the ruggedness is proved from implementing the sensor in a flow measurement system. The sensor is produced from readily available materials with a simple process, and it is easily regenerated from heat treatment. 

All output signals from temperature sensors and flow controllers are sampled with a commercial acquisition system connected to a PC and data are presented on the screen using a LabView set-up. For the measurements of the cylinder pressure a high speed data acquisition system is installed which also is connected to the PC. 

The fuel cell system is equipped with several sensors able to measure the air and water flow rates, the temperatures of cathode outlet stream and of water in cooling circuit, the hydrogen pressure, stack current and voltage, and individual... 

In addition to reaction chambers and delivery systems, a number of supervising and sensor systems are of utmost importance for control and safety reasons. Sensors in automated workstations include measurement of temperature (thermocouple, thermistor, semiconductor), pressure, liquid flow and gas or liquid level. To monitor the presence or absence of vessels or devices, systems like capacitance, inductivity, ultrasonic monitors, magnetic sensors or optical sensors (reflective, beam interruption, color) can be integrated in automated workstations. 

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