Modular sorption test bench to investigate adsorption chillers, adsorption thermal energy storage units, adsorption heat pumps, and adsorption heat transformers


Engelpracht, Mirko © Copyright: Lehrstuhl fuer Technische Thermodynamik der RWTH Aachen


Mirko Engelpracht

Group Leader Sorption Systems Engineering


+49 241 80 98176



Our department's modular sorption test bench is used flexibly to investigate closed adsorption processes, such as adsorption chillers, adsorption heat pumps, or adsorption heat transformers. For this purpose, the test bench consists of the four vacuum-tight main components 1) evaporator, 2) condenser, 3) adsorber, and 4) reservoir (see Figure), which can be connected or disconnected from each other using controllable valves. Heat exchangers are integrated into each of the main components evaporator, condenser, and adsorber. Inlet conditions of the secondary circuits of the heat exchangers are conditioned using thermostats. In addition, the condenser and adsorber are equipped with optionally operable condensation protection heaters to prevent condensation on vacuum vessels and connecting lines. The unique feature of the test bench is the modularity of the evaporator and adsorber: Both components have a removable cover (vacuum system: DN 320 ISO-K flanges), allowing their heat exchangers and, thus, the adsorption material to be replaced quickly.

The modular sorption test bench is equipped with different measurement sensors for evaluating adsorption processes. The three heat exchangers are assessed using temperature and volume flow sensors in their secondary circuits. In addition, the main components are equipped with absolute pressure transducers and temperature sensors in their liquid and vapor phases as well as on their casings and in the adsorption material. The measurement data recording and test bench control are fully automated using a LabVIEW-based control program.

The most important key data of the test bench is given in the Table below. Further details of the test bench, such as dimensions, component weights, or measurement sensors used, can be taken from our open-source publication on the experimental demonstration of the operation of an adsorption heat transformer.

Table containing key data of test bench

Evaporator: Volume flow rate

4-12 L/min

Evaporator: Temperature

5-90 °C

Condenser: Volume flow rate

4-7 L/min

Condenser: Temperature

5-65 °C

Adsorber: Volume flow rate

4-10 L/min

Adsorber: Temperature (cold)

25-90 °C

Adsorber: Temperature (hot)

25-140 °C

Condensation protection heater of adsorber: Temperature

25-95 °C

Condensation protection heater of condenser: Temperature

Ambient-80 °C

All temperature sensors were calibrated using two highly accurate Ahlborn temperature sensors. The measurement uncertainty of all temperature sensors is less than 0.06 K. The measurement uncertainty of all volume flow sensors is 0.5% of the measured value, and the measurement uncertainty of the pressure transducers is 1 mbar. All uncertainties apply for a simple standard uncertainty.

  Photo of the modular sorption test bench Copyright: © Institute of Technical Thermodynamics, RWTH Aachen University left, top - condenser; left, middle - reservoir; left, bottom - evaporator; right - adsorber