Laboratory of Sorption Processes

Test rigs and analytic

In the laboratory there are different working stations with various programmes installed on the computers, for example:

Aspen Plus is a process simulation software, especially for the chemical industry. It allows to model and simulate various chemical processes. The main use in the laboratory is the design of heat exchangers as well as in the development of new processes.

COMSOL Multiphysics® is a general-purpose simulation software for modeling designs, devices, and processes in all fields of engineering, manufacturing, and scientific research. In the laboratory innovative adsorber heat exchangers for th eapplication in sorption processes are being simulated with this program.

gPROMS (short for general PROcess Modelling System) is a single software platform that provides all core capabilities for digital process design and operations applications, from formulation and R&D through engineering design and manufacture to product performance, for diverse process industry sectors.

LabVIEW is a system-design platform and development environment for a visual programming language from National Instruments. With LabVIEW automated test and automated measurement systems can be developed and their performance can be increased.

Polysun is a software to design and implement efficient, innovative and comprehensive energy concepts. It is possible to simulate complex linked heating systems like heat pumps and pellet boilers with thermal solar collectors and seasonal buffer storages, photovoltaics and wind turbines for the energy supply of buildings.

With the heat pump test rig the standard measuring conditions (volume flow rates and return flow temperatures) for the evaluation of the seasonal performance factors of electrical- and gas-powered heat pumps can be adjusted very precisely according to the specifications of VDI-4650-1, VDI-4650-2 guidelines and the DIN EN 12309; 2014 standards. Accordingly, heat pumps can be investigated concerning their heating power and their coefficient of performance under the requested operating conditions. To this aim, the electrical power consumption or – in the case of gas powered heat pumps – the gas consumption is determined. In general, the test rig includes a heating loop and a brine loop. The heating loop simulates the heating water cycle of a house, whereas the brine loop offers the ambient heat from the heat source (for example from ground water, geothermal and solar collectors). The heat is then transferred to the evaporator of the heat pump. To calculate the coefficient of performance (COP) of the heat pump, the heating output delivered to the heating loop is divided by the driving energy (either electricity or gas).
Maximum power; brine loop:    4,5 kW
Maximum power; heating loop:    16 kW

 

Heat Pump test rig
Heat Pump test rig

With the adsorption-kinetics test rig the speed of adsorption and desorption processes under quasi isobaric or quasi isothermal conditions can be experimentally investigated. The output result gives precise information on how fast a certain adsorbent (zeolite, silica gel, MOFs, etc.) adsorbs or desorbs vapour on (or out of) its surface under prescribed initial and final operating conditions of an adsorption chiller, heat pump, storage or heat transformer. The test rig is designed to investigate small amount of samples in order to compare different adsorbents or adsorbent configurations (loose pellets, mono- or multi-layers as well as coating with different thicknesses and techniques) under same operating conditions. The obtained results are used together with simulation models in COMSOL Multiphysics or gPROMS to estimate the combined heat- and mass transfer characteristics of the analysed samples, which paves the way to dedicatedly design and simulate the adsorber heat exchanger. Among other parts, the test bench includes a measuring cell, a vapour tank, an evaporator and a vacuum pump.

Samle mass200-400 mg
Sample carrier temperature-25 °C bis 120 °C
Volume vapour tank50 l
Vapour pressure2 mbar bis 200 mbar
Temperature range vapour tank-25 °C bis 60 °C
kinetics test rig
kinetics test rig

In this test facility the heat and mass transfer taking place during the two different operating stages (absorption-evaporation and desorption-condensation) of a periodically operating absorption heat pump or heat storage can be analysed. The test facility consists of two identical components with a vacuum valve in the connecting tube. Both heat and mass exchangers are constructed as falling film heat and mass exchangers. The first running of this test facility has been successfully realized with the help of the heat pump test rig, which is already available in the laboratory. For future investigations of absorption/adsorption and desorption kinetics on the component scale of a sorption machine, a dedicated setup, the so-called “big-scale sorption kinetics test rig” is now under development.

Test facility of a periodic absorption heat pump/ heat storage
Test facility of a periodic absorption heat pump/ heat storage

With the degassing unit, gases dissolved in water (like oxygen, nitrogen and carbon dioxide) are removed to avoid any mal operation due to the evolvement of such inert gases inside the components of adsorption or absorption components or systems. In one batch, a maximum of 10 litres of water can be degassed. The degassed water is drawn from the unit under vacuum in a vacuum-sealed container and are filled in into the different test facilities also under vacuum.

Water degassing unit
Water degassing unit

In the thermal conductivity test rig both the thermal conductivity and the thermal diffusivity of solids, liquids, gels and granulates can be measured with an accuracy better than 3% at different temperatures. In addition, the measurements can be carried out on different materials under vacuum. For both measurements the so-called “Transient-Hot-Bridge” (THB) process is used. It is a further development of the so called “Transient-Hot-Strip” (THS) method. Both procedures are transient measurement methods, which means that both are dependent on time. In contrast to steady-state measurement methods they offer much shorter testing times. The test rig is equipped with a dedicated vacuum pump, an electrical heater and a cooling thermostatic circulating bath.

Thermal conductivity test rig
Thermal conductivity test rig

The vacuum furnace by Vacucell (type: evo-line) is used for drying the adsorbents or heat exchangers for vacuum applications.

Chamber volume55 l
Ambient temperature+5 °C to +40 °C
Maximum attainable vacuum   5,0∙10-4 mbar
Working temperaturefrom 5 °C above ambient temperature up to 250 °C

    
    

    

 

Vacuum furnace
Vacuum furnace

For the investigation of the reaction kinetics in thermochemical processes encountered in CO2-capturing as well as hydrogen storage processes, a TGA-DSC ( Thermogravimetric analysis - Differential Scanning Calorimetry) measuring instrument was purchased.

With the high precision analytical balance (KERN, type: ALS 250-4A) minor samples can be weighed very precisely. Such accurate measured samples are needed, for example, in the adsorption-kinetics test rig, where low sample masses down to 200 mg are required, which should be weighed with a very high precision.

Maximum weight250 g
Accuracy±0,1 mg

 

High precision analytical balance
High precision analytical balance

With the portable helium leak detector (Leybold, type: L300i) leak tests are carried out, for example on valves or components for adsorption or absorption systems, in order to assure their inert gas free  and, therefore, sustainable operation . Advantages of leak test with helium include among others high sensibility, non-destructive tests and a good repeating accuracy. 

Detectable leak rate5∙10-12 mbar l/s
Maximum allowable inlet pressure15 mbar
Ready for operation< 2 min

  

Helium leak detector
Helium leak detector

Software tools