Kinetic test bench to determine temperature induced ad- und desorption kinetic for closed-loop adsorption processes

 

The institute's kinetics test bench is used to investigate the kinetics of various working pairs for closed adsorption processes, such as adsorption chillers, heat pumps, or heat transformers. The test rig consists of three main components 1) a kinetics cell, 2) an evaporator, and 3) a vapor volume, which can be connected or disconnected using controllable valves. The (saturated steam) pressure in the test bench can be adjusted via the temperature in the evaporator and the temperature inside the test bench via the heat exchanger of the kinetic cell. A unique feature of the setup is the infrared camera, which can record the sample temperature from outside through the top of the kinetic cell.

The kinetic cell is subjected to a temperature jump that takes place within a few seconds to evaluate the adsorbents under investigation. Then, heat and mass transfer coefficients can be determined from the step responses in the pressure signal and the infrared temperature of the sample by employing dynamic simulation and optimization. In addition, all components are equipped with condensation protection heaters to prevent condensation of the working fluids on the vacuum housings and connecting lines during sub-atmospheric pressure. The entire test bench is built into a climatic chamber where temperature can be adjusted and humidity can be reduced to guarantee the repeatability of the experiments. The fully automated test bench control and measurement data recording are performed by means of a LabVIEW control program.

The most important key data of the test bench can be taken from the following table. All further details of the test bench can be taken from the following publication.

Table with key data of the test bench

Kinetic cell: Sample mass	20-2000mg
Kinetic cell: Sample geometry	Bulk or Coating
Kinetic cell: Heat exchanger area	Ø 35 mm
Kinetic cell: Temperature jumps	5-95 °C
Evaporator: Temperature	-20-35 °C
Evaporator: Pressure	0-1000 mbar

All temperature sensors are calibrated by means of two highly accurate Ahlborn temperature sensors. The measurement uncertainty of the high-precision pressure sensor is 0.1% of the measured value so that even adsorption on the smallest samples can be investigated.

  Copyright: © Institute of Technical Thermodynamics of RWTH Aachen Top, middle – Vapor volume; Middle – Evaporator; Right – Kinetic cell;