Ultrasonic flow meter / energy meter

DESCRIPTION

The DXN Portable Ultrasonic Flow and Energy Meter is a true hybrid instrument, capable of measuring liquid flow with multiple technologies, including: Doppler, transit time and liquid thermal (heat energy) flow. Easy to install by clamping onto the outside of the pipe, the DXN measures flow using non-invasive ultrasonic sensors. Compatible with a pipe wall thickness gauge, inside pipe diameter can be verified to ensure accurate ultrasonic
measurements when piping details are unknown or unavailable. The DXN has a number of advanced features including a touchscreen interface, full-color graphing, wizard-based start-up configuration, USB connectivity, and Modbus TCP/IP connectivity.
These features make it easy for technicians to obtain accurate readings while capturing flow surges and high-speed batch operations. The DXN captures and displays multiple user-defined and application parameters at once and can record the data with an easy-to-use data logging function. The ability to monitor and record several parameters at once allows technicians to verify and troubleshoot permanent flow installations with ease.
 
OPERATION
Transit time flow meters measure the time difference between the travel time of an ultrasound wave going with the fluid flow and then against the fluid flow. This time difference is used to calculate the velocity of the fluid traveling in a closed-pipe system.
The transducers used in transit time measurements operate alternately as transmitters and receivers. Transit time measurements are bi-directional and are most effective for fluids that have low concentrations of suspended solids.
Doppler flow meters operate by transmitting an ultrasonic wave from a transducer through the pipe wall and into the moving liquid. The sound wave is “reflected” by suspended particles or bubbles moving with the liquid and ultimately gathered by the receiving transducer. A frequency shift (Doppler effect) will occur that is directly proportional to the speed of the moving particles or bubbles. This shift in frequency is interpreted by the digital signal processor (DSP) and converted to a fluid velocity measurement.
Using its built-in hybrid technology, the DXN will automatically choose which type of flow measurement to read based on signal quality during operation. Regardless of the method used to determine velocity, multiplying the pipe’s cross-sectional area by the fluid velocity produces a volumetric flow rate. The measurement also presumes that the pipe is completely full during the measurement cycle.
When used in conjunction with flow measurement, temperature measurements can yield energy usage readings in the form of heat flow. To find the net heat loss or gain, energy usage is calculated by multiplying the flow rate of the heat transfer fluid by the change of heat content in the fluid after it has done some kind of work An ultrasonic meter equipped with heat flow capabilities measures the rate and quantity of heat delivered or removed from devices
such as heat exchangers. The instrument measures the volumetric flow rate of the heat exchanger liquid, the temperature at the inlet pipe and the temperature at the outlet pipe.


Rate of Heat Delivery = Q * (TIn - TOut) * C * ρ
Where…
Q = Volumetric flow rate
TIn = Temperature at the Inlet
TOut = Temperature at the Outlet
C = Heat Capacity
ρ = Density of fluid
By applying a scaling factor, this heat flow measurement can be
expressed in the units of your choosing (Btu, Watts, Joules, Kilowatts
and so on).