Parasitic Energy Calculator

This package calc_pe computes the parasitic energy for CO₂ capture from CO₂ and N₂ isotherms.

Install

git clone https://github.com/danieleongari/calc_pe.git
cd calc_pe
pip install .

Input and run

$ calc_pe Mg-MOF74 coal -rho 914.88 -cp 896 -process TPSA -datapath ./tests/

See calc_pe --help for the input description.

Use calc_pe --log for printing the debug log file.

NB:

• The isotherm data should be put in the {datapath}/{structure_name} folder.

• The temperature at which the isotherm data is calculated is automatically read from the filename {datapath}/{structure_name}/{adsorbate_name}/{temperature}.csv.

• Isotherms are fitted using pyiast.InterpolatorIsotherm with fill_value = uptake.max(). Therefore, the isotherm should be well saturated, because for higher pressures the loading is extrapolated as the maximum uptake.

• The heat of adsorption (HoA) needs to be provided in kJ/mol for all the loading pressures of the isotherm. It is needed to shift the original isotherm to a new temperature using the Classius-Clapyeron equation. Note that the HoA is defined here with a NEGATIVE value.

• You can provide density and cp as single value files cp.csv and rho.csv: see the tests as example.

• For testing the minimal inputs are:

$ cd tests/
$ calc_pe Mg-MOF74 coal
$ calc_pe HKUST-1 coal

Output

In the output, the program prints:

Mg-MOF74: PE(MJ/kg)= 0.867: Pd(bar)= 0.01 Td(K)= 333.0 EL(-) = 0.235 Q(MJ/kg)= 0.124 Wcomp(MJ/kg)= 0.743 WCv(kg/m3)= 114.655 WCg(kg/kg)= 0.193 pur(-)= 0.967

• Name of the adsorbent
• PE(MJ/kg): parasitic energy per kg of CO₂ (Note: PE=Q+Wcomp)
• Pd(bar): optimal desorption pressure
• Td(K): optimal desorption temperature
• EL(J/J): fraction of electricity loss
• Q(MJ/kg): heat requirement
• Wcomp(MJ/kg): compression work
• WCv(kg/m3): volumetric working capacity, i.e., mass of CO₂ produced per m² of bed, considering -vf void fraction.
• WCg(kg/kg): gravimetric working capacity, i.e., mass of CO₂ produced per kg of bed, considering -vf void fraction.
• pur(mol/mol): molar fraction of CO₂ final purity (-)

A warning is printed in case of negative working capacity for all the tested desorption conditions, e.g.:

$ calc_pe HKUST-1 air
HKUST-1: Unfeasible process!

NB:

• The Henry coefficient for CO₂ is a good pre-screening parameter

• The working capacity is also very important, since it allows for less cycles using the same amount of adsorbent (or less adsorbent needed with the same cycles).

• The final CO₂ purity is less than the imposed purity, -yd (default: 0.99): we use the yd value as an approximation of the gas phase at desorption to get the uptake in the adsorbent at the desorption condition (using IAST). Note that the PE is not very sensitive to yd (see Joos et al. (2016)) and there is not a motivated need for reiteration. The final CO₂ purity is computed as the working capacity of CO₂ over the sum of the working capacities of both CO₂ and N₂.

• By default the program prints the results for optimal PE (i.e., the lowest). However, one can search for other optimal parameters by using the -opt command: lowest Q if he is not interest in compressing the CO₂, highest working capacity (WC) or highest CO₂ final purity (pur). Note that these may not be anymore optimization problems, returning just the max/min T and P conditions.

Dependencies

calc_pe uses:

• pyIAST
• numpy
• pandas

References

If you use calc_pe, please consider citing:

• Evaluating different classes of porous materials for carbon capture (2014)
• In silico screening of carbon-capture materials (2012)

This program has been used in:

• Building a Consistent and Reproducible Database for Adsorption Evaluation in Covalent–Organic Frameworks

Authors

• Johanna M. Huck
• Li-Chiang Lin
• Cory M. Simon
• Adam Berger
• Daniele Ongari (restyling, December 2018)