Performance of a CO2 sorbent for indoor air cleaning applications: Effects of environmental conditions, sorbent aging, and adsorption of co-occurring formaldehyde.
Indoor Air
; 30(6): 1283-1295, 2020 11.
Article
en En
| MEDLINE
| ID: mdl-32453891
ABSTRACT
Indoor air cleaning systems that incorporate CO2 sorbent materials enable HVAC load shifting and efficiency improvements. This study developed a bench-scale experimental system to evaluate the performance of a sorbent under controlled operation conditions. A thermostatic holder containing 3.15 g sorbent was connected to a manifold that delivered CO2 -enriched air at a known temperature and relative humidity (RH). The air stream was also enriched with 0.8-2.1 ppm formaldehyde. The CO2 concentration was monitored in real-time upstream and downstream of the sorbent, and integrated formaldehyde samples were collected at different times using DNPH-coated silica cartridges. Sorbent regeneration was carried out by circulating clean air in countercurrent. Almost 200 loading/regeneration cycles were performed in the span of 17 months, from which 104 were carried out at reference test conditions defined by loading with air at 25°C, 38% RH, and 1000 ppm CO2 , and regenerating with air at 80°C, 3% RH and 400 ppm CO2 . The working capacity decreased slightly from 43-44 mg CO2 per g sorbent to 39-40 mg per g over the 17 months. The capacity increased with lower loading temperature (in the range 15-35°C) and higher regeneration temperature, between 40 and 80°C. The CO2 capacity was not sensitive to the moisture content in the range 6-9 g/m3 , and decreased slightly when dry air was used. Loading isothermal breakthrough curves were fitted to three simple adsorption models, verifying that pseudo-first-order kinetics appropriately describes the adsorption process. The model predicted that equilibrium capacities decreased with increasing temperature from 15 to 35°C, while adsorption rate constants slightly increased. The formaldehyde adsorption efficiency was 80%-99% in different cycles, corresponding to an average capacity of 86 ± 36 µg/g. Formaldehyde was not quantitatively released during regeneration, but its accumulation on the sorbent did not affect CO2 adsorption.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Dióxido de Carbono
/
Contaminación del Aire Interior
/
Filtros de Aire
/
Formaldehído
Tipo de estudio:
Prognostic_studies
Idioma:
En
Revista:
Indoor Air
Asunto de la revista:
SAUDE AMBIENTAL
Año:
2020
Tipo del documento:
Article
País de afiliación:
Estados Unidos