Magnetic suspension balance to measure adsorption equilibria


The thermo-gravimetric analytics scale (TGA) is used to determine data on the adsorption equilibrium and kinetics (large-pressure jump) of adsorption pairs for adsorption heat transformers and gas separation. The data forms the basis for model-based design and analysis of adsorption processes. TGA devices are particularly suitable because they do not require carrier gas. Carrier gases affect adsorption kinetics and, to a lesser extent, adsorption equilibrium so that data from adsorption pairs for use in adsorption heat transformers or gas separation are distorted.

Another special feature of the TGA is a sample and weighing chamber separated by the magnetic suspension coupling: Condensation of vaporous sorptives (e.g., water) in the weighing chamber is therefore eliminated while condensation in the sample chamber is eliminated by condensate protection heaters. In addition, both large pressure and temperature ranges as well as the handling of toxic and explosive sorptives can be easily realized in the closed sample chamber.


Table with key data of the test bench

Measuring Cell: Sample mass

0,01-5000 mg

Measuring Cell: Sample geometry


Measuring Cell: Temperature

-40-400 °C

Measuring Cell: Pressure

0-150 bar

Measuring Cell: Working Fluids

H2O, He, N2, O2, CO2, …

Evaporator: Temperature

-40-130 °C

Evaporator: Pressure

0-3 bar

All temperature sensors are highly accurate Ahlborn temperature sensors. In total, the pressure range is covered by 5 Keller pressure sensors. The high-precision Sartorius laboratory scale detects even the smallest changes in mass without being influenced by the operating conditions of the sample chamber.

  Figure of the magnetic suspension balance Copyright: © Institute of Technical Thermodynamics of RWTH Aachen Left Gas dosing station; Middle Suspension balance; Right workplace