T7 in a stirling engine dynamometer

This is a good example of how LabJack devices are used in the wild. Martin Beck, an engineer working with VE Engineers in Germany, employed the T7-PRO for data acquisition within a dynamometer. The dynamometer is used to measure the output from a stirling engine.

Signals Acquired

• Eight (8) temperatures through Type K Themocouples. Directly connected to T7-PRO´s CB37 board without further amplification. Sample rate = 1 Hz. CJ compensation via LM34CAZ.
• Torque, ±50 Nm. Output of torque-gauge ±10V. Directly connected to LabJack T7-PRO. Sample rate = 1 kHz.
• Absolute internal pressure, 0-20 bar abs. Output of pressure transducer 0-10V. Directly connected to LabJack. Sample rate = 1 kHz.
• Crankshaft angle and velocity. Incremental encoder with quadrature output. 360 tics per rev max. 36 kEdges per sec. Directly connected to LabJack. Counter is quadrature counter. Sampling of Counter value with 1 kHz. Resetting of counter through inductive initiator.

A view of the electronics enclosure on the side of the engine/dyno.

The engine setup

Another view

Close-up of the engine

The heat source for the stirling engine exposed for viewing.

Much information is derived from the acquired data, such as thermal and mechanical power, efficiency, etc. Quite a few graphs are automatically generated, such as high speed data over time and over crankshaft angle; p-over-V diagram; Power, Torque, Efficiency over velocity, etc.

The application was programmed in LabVIEW using the LJM Library and LJM LabVIEW example code. Other active components are a frequency inverter from SEW-Eurodrive and a temperature controller from Watlow, both with Modbus/TCP interfaces. This makes a very neat system concept, with just one Ethernet cable coming out of the machine for the entire control and data acquisition.