Modeling the Adsorption of MixedGases Based on Pure

Modeling the Adsorption of Mixed-Gases Based on Pure Gas Adsorption Properties Nir Tzabar, Harry J. Holland, Cris H. Vermeer, Marcel H. J. ter B Energy, Materials and Systems Faculty of Science and Technology University of Twente

Outline 1. Motivation 2. Pure gas adsorption measurements 3. Sips isotherms 4. Mixed gas adsorption calculations 5. Summary CEC-ICMC, Tucson AZ, Nir Tzabar, July 2015

1. Motivation Ø Joule-Thomson (JT) sorption cryocoolers have no moving parts; therefore, are free of vibrations and have potentially a long lifetime. Ø Mixed-Regrigerants allows lower operating pressures for JT cryocoolers (relative to pure gases) and higher COPs. Ø This study is a step in a research on mixed-refrigerant JT sorption cryocooling Developing an effective model to determine the adsorption of mixed gases out of pure gas adsorption isotherms for the research on JT sorption cryocoolers CEC-ICMC, Tucson AZ, Nir Tzabar, July 2015

2. Pure gas adsorption measurements Experimental setup Vacuum Pump Heater V 3 Connecting Tube T Sorption Cell V 1 V 2 P Pi Coriolis Flow Controller V Gas Source N 2 / CH 4 / C 2 H 6 / C 3 H 8 Norit-RB 2 Activated carbon, steam activated, extruded carbon. CEC-ICMC, Tucson AZ, Nir Tzabar, July 2015

2. Pure gas adsorption measurements Experimental results 400 K Nitrogen 300 3 K 20 K 340 Methane K 360 K 380 K Propane CEC-ICMC, Tucson AZ, Nir Tzabar, July 2015 Ethane

3. Sips Isotherms C – adsorption concentration p – pressure C 0 – the saturated adsorption concentration a – the adsorption affinity n – adsorption heterogeneity parameter CEC-ICMC, Tucson AZ, Nir Tzabar, July 2015

3. Sips Isotherms Linearization: CEC-ICMC, Tucson AZ, Nir Tzabar, July 2015

3. Sips Isotherms CEC-ICMC, Tucson AZ, Nir Tzabar, July 2015

3. Sips Isotherms Symbols – Experimental results Solid lines – Sips model 300 K 320 K 340 K 360 K 380 K 400 K CEC-ICMC, Tucson AZ, Nir Tzabar, July 2015

3. Sips Isotherms Modified Sips model CEC-ICMC, Tucson AZ, Nir Tzabar, July 2015

3. Sips Isotherms Modified Sips model Symbols – Experimental results Dashed lines – Modified Sips model CEC-ICMC, Tucson AZ, Nir Tzabar, July 2015

3. Sips Isotherms CEC-ICMC, Tucson AZ, Nir Tzabar, July 2015

4. Mixed gas adsorption calculations The composition of the adsorbed phase: The adsorption selectivity: CEC-ICMC, Tucson AZ, Nir Tzabar, July 2015

4. Mixed gas adsorption calculations Nitrogen - Methane Nitrogen - Ethane 300 K i 300 K Nitrogen - Propane 300 K j x – molar fraction in the adsorbed phase y – molar fraction in the vapor phase CEC-ICMC, Tucson AZ, Nir Tzabar, July 2015 = 0. 22 @ 10 bar

5. Summary Ø The adsorption of nitrogen, methane, and propane on Norit-RB 2 activated carbon have been measured. Ø The Sips adsorption model is used to describe the adsorption isotherms, and a linearization method is used to determine the parameters out of the experimental results. Ø A modified Sips model that incorporates the temperature dependence is suggested. Ø The adsorption model is further developed for the adsorption of gas mixtures. Ø The adsorption selectivity is discussed and the results of nitrogen-methane, nitrogenethane, and nitrogen-propane are presented. Ø Future work: I. Pure gas adsorption measurements on other adsorbents II. Experimental verification of the mixed gases adsorption model III. Using the modified Sips model in a sorption compressor analysis CEC-ICMC, Tucson AZ, Nir Tzabar, July 2015

Thank you for your attention CEC-ICMC, Tucson AZ, Nir Tzabar, July 2015