CONTINUOUS DIRECT OHMIC HEATING - INSTRUCTIONS

Measurement procedure

Simplest experiment with tap water. Switch on PC, and power supply of transducers. Start program OHMICAS (time step 1 s, 9 channels). Set 3-way cock K1 to position 1 (K1/1), and open valve V2 (filling water). Check water level visually (glass gauge) and on display (channel 8). After filling close V2. Set cock K3/1 and K1/4. Water flows to the outlet. Estimate the flowrate using F10. Adjust the flowrate by valve V1. Switch on heating and adjust electrical power (check overloading on control panel). Wait until the steady state is achieved. Precise value of flowrate can be obtained by measurement of volume at a time. Use stop-watch and calibrated vessel (2 to 8 liters).

Photogallery

Filling the tank by water - Check the level of water by electronic gauge and visually

Set the valve at outlet (flowrate adjustment). Flowrate measurement. Positions of 3-way cocks.

Viscous liquids-driving pressure of compressed air adjustment

Control and Computer (temperature/level/power/ measurement)

Electrical conductivity probes, electronics connection

Disassembly of head, heating tank and electrodes

Assembly of electrodes and heating tank

Circuit diagrams
Power control
Temperature (Pt100)

Power sockets and PC connector

Conductivity (connectors and diagrams)

PC-program for monitoring T,P,V,C
Program OHMICAS displays and records data from max.16 channels of A/D PCL 818 card (Single Ended analog inputs). Channels 1-6 are temperatures [C] (tank from bottom to head), 7 electrical power [kW], 8 liquid level [liters], 9-11 temperatures [C] (inlet temperature in head and temperatures in tanks), 12-15 conductivities, and channel 16 is auxilliary. Voltage (in the range +-10 V) is converted to physical quantities by linear transformation.

Calibration (graphs and equations)
Liquid level (august 98)
Pt100 (september 99)
Power (september 99)
Properties of processed materials

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