In response to the growing demand for smart metering, Morgan Technical Ceramics has developed ultrasonic piezoceramic sensors for high reliability gas flow measurement which make the high volume manufacture of ultrasonic domestic gas meters a reality. Ewan Campbell from the company explains.
As the technology behind today’s clean energy initiatives is refined and evolved, it is often incremental advances in the performance of critical components that allow step changes in commercial advancement and application. One such advancement is in ultrasonic piezoceramic sensors for measurement of gas and liquid flows, driven by increased global demand for smart metering.
Smart metering is fast becoming recognised as an important way to improve the efficiency of utility supplies and help all of us to reduce energy use in the home. According to the Department of Energy & Climate Change, energy suppliers will be responsible for replacing more than 53 million gas (and electricity) meters by 2019. The roll out is expected to save the UK £14 billion in energy costs, playing an important role in the transition to a low carbon economy.
In response to this fast growing demand, Morgan Technical Ceramics has developed new ultrasonic piezoceramic sensors which provide utility companies and OEMs with high reliability, accurate gas measurement, cost-effectively – making high volume manufacture of ultrasonic domestic gas meters a reality.
The new sensors are just 20mm in diameter (Fig 1) and can be integrated easily in ultrasonic flow measurement systems and smart metering systems for measuring natural gas. There are no moving parts so the sensor is not subjected to wear, providing a more reliable method of measurement over the long term than traditional mechanical systems such as positive displacement or diaphragm technologies, for example.
Sensor operation
The piezoceramic sensor operates using a ‘time-of-flight’ measurement (Fig 2). A pair of sensors is used to transmit and receive ultrasonic pulses across the gas flow channel. The time taken for the signal to travel between the sensors can be used to give a very accurate measurement of the gas flow rate, even at low flow speeds.
The measurement is robust as it is not sensitive to temperature or pressure variations (i.e. it does not depend on the speed of sound), and stable over the long term.
These ultrasonic piezoceramic sensors were designed by the engineering team at Morgan Technical Ceramics for domestic gas metering applications using matching polymer layers and 3D finite element analysis, a sophisticated software modelling technique. The engineers were able to create virtual prototypes, which significantly reduced the design cycle.
Specifically, the team was able to optimise efficiency and bandwidth of the sensor. Improving its efficiency to transfer ultrasonic energy into the gas means that the meter requires less battery power. Improving the bandwidth allows the sensor to use shorter pulses, for a more accurate time-of-flight measurement.
Morgan Technical Ceramics is working with a number of the leading gas meter manufacturers who have been testing the new piezoceramic sensors with very positive results. The company is also supplying piezoceramic material optimised for this application into the global market.
Level and liquid flow
Piezoceramic sensors, however, are not restricted to gas flow measurement. They are also suited to level and flow measurement of liquids, including smart domestic metering applications such as water and heat. Morgan Technical Ceramics supplies sensors for all these applications and its dedicated transducer research and development team also works closely with customers to create bespoke sensors for specific applications.
Time-of-flight measurement
It is an inherent property of the piezoelectric ceramic material that when an electrical signal is passed through the ceramic it develops strain. When this occurs at high frequency it generates a sound wave. Conversely, when a sound wave comes into contact with the ceramic it comes under stress and produces an electrical signal. Hence, the gas flow rate can be measured by calculating the time from transmission of a pulse to the time of receiving the echo.
MTC ElectroCeramics’ piezoceramic materials have exceptional mechanical and electrical properties and offer excellent bandwidth and sensitivity for accurate measurement readings. Furthermore, temperature stability of the piezoceramic materials is critical to ensure accurate measurement across the whole spectrum of ambient conditions to which a meter is typically exposed.
Morgan Technical Ceramics
www.morgantechnicalceramics.com