Effects of Vapor Pressure of Desiccant Solution on Mass Transfer Performance for a Spray-Bed Absorber
Abstract
:1. Introduction
2. Experimental Section
2.1. Experimental Procedure
2.2. Measuring System for Vapor Pressure
- (1)
- The desiccant solution is placed in STIR.
- (2)
- Liquid nitrogen in the Dewar bottle was used to freeze or solidify the desiccant solution for about 10 min.
- (3)
- The valvesV2 and V4 are closed. The vacuum pump was activated firstly and then the valves V1, V3, V5, and V6 are opened for degassing. (solid state still for the desiccant solution)
- (4)
- After activating the vacuum pump, the system through V1, V3, V5, and V6 is degassed by the vacuum pump.
- (5)
- While reaching the vacuum state, V1 could be closed to maintain the vacuum state of the system through V1, V3, V5, and V6 and vacuum pump could be close to save energy.
- (6)
- The temperature of heating stirrer is increased to defrost the desiccant solution.
- (7)
- Steps 2–6 are repeated three times to remove impurities in the system.
- (8)
- The temperatures of the desiccant solution, 20, 25, 30, and 35 °C, controlled by heating stirrer were used to meet experimental demand. The vapor pressure of the desiccant solution was obtained by a pressure gauge after reaching the equilibrium state between gas and liquid phases.
2.3. Spray-Bed Absorber and Operating Procedure
3. Results and Discussion
3.1. Vapor Pressure of the Desiccant Solution
3.2. Mass Transfer Performance Compared with Literature Data
3.3. Effects of Operating Variables on Mass Transfer Coefficient
3.4. Mass Transfer Correlation
4. Conclusions
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
Nomenclature
Symbols |
At: surface area of the packing per unit volume of the bed, 1/m |
c: molar concentration (mol/m3) |
Cv: mass-transfer factor, Dimensionless |
D: diffusion coefficient, m2/s |
dc = column diameter, m |
de: equivalent diameter, 4ε/ad, m |
dn: nozzle diameter, m |
G: gas flow rate, L/min |
Gr: Grashof number, dimensionless |
hk: local mass transfer coefficient, kg/m2s |
HkA: overall mass transfer coefficient, kg/m3s |
hL: Liquid holdup, Dimensionless |
hm: mass transfer coefficient, g/m2s |
HmA: overall mass transfer coefficient, g/m3s |
kk: local mass transfer coefficient, kgmole/m2s |
km: local mass transfer coefficient, mole/m2s |
KmA: overall mass transfer coefficient, mole/m3s |
KW: wall factor, dimensionless |
L: liquid flow rate, L/min |
Ls: superficial liquid mass velocity, kg/m2s |
M: molecular weight of water, kg/mol |
m: mass flow rate, kg/s |
P: pressure, atm |
PH2O: partial pressure of water pressure, mmHg |
PTEG: vapor pressure of TEG solution, mmHg |
R: ideal gas constant, m3atm/kmol·K |
Re: Reynolds number, ρvdc/μ |
S: superficial mass velocity, kg/m2s |
Sc: Schmidt number, μ/Dρ |
Sh: Sherwood number, dimensionless |
T: Temperature, ºC |
Ts: solution temperature, °C |
v: fluid flow velocity, m/s |
V: gas molar flow rate, kmole/m2s |
X: concentration in mole fraction |
yAin: molar ratio of component A in inlet gas |
yAout: molar ratio of component A in outlet gas |
: molar ratio of component A at equilibrium state |
Z: height of the absorber |
Greek Symbols |
ɛ: packing porosity or void fraction, dimensionless |
α: regressed parameter for the correlation |
β: regressed parameter for the correlation |
γ: regressed parameter for the correlation |
δ: regressed parameter for the correlation |
η: regressed parameter for the correlation |
μ: fluid viscosity, kg/ms |
ρ: fluid density, kg/m3 |
σ: surface tension, kg·m/s2 |
Subscript |
a: air |
G: gas phase |
L: liquid phase |
s: solution |
w: water |
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Device Type | Absorbent | Absorbate | Variable | Response | Reference |
---|---|---|---|---|---|
packed bed | CaCl2 | H2O | TG | COP air mass ratio | [1] |
packed bed | LiCl | H2O | G, L, Q, ε | evaporation rate | [2] |
packed bed | LiCl LiBr KCOOH | H2O | TG, TL, Gs, Ls, H, CL | removal rate regeneration rate pressure drop | [3] |
packed bed | LiCl LiBr CaCl2 | H2O | TG, TL, H, G, L | removal rate and efficiency | [4] |
packed bed | MEA | CO2 | packing type | pressure drop operating cost | [5] |
packed bed | MEA-glycerol | CO2 | TL, G, CL | K ε | [6] |
structured packed bed | TEG | H2O | G, L, TG, TL, H, CL | removal rate ε | [7] |
structured packed bed | TEG | H2O | G, L, H, TL, CL | evaporation rate ε | [8] |
structured packed bed | LiCl | H2O | G, L | K | [9] |
structured packed bed (heating tower) | glycol solution | H2O | Gs, Ls, TG, TL, H, CL | removal rate ε thermal efficiency | [10] |
rotating packed bed | LiCl | H2O | g, Gs, Ls, inlet parameters of air and liquid | removal rate H, K, ε | [11] |
rotating packed bed | ([CPL][TBAB])IL | SO2 | r, TL, G, L | ε | [12] |
spray bed | polyethylene glycol | H2O | Gs, Ls, CL, TL, dn | K | [13] |
spray bed | CaCl2 aqueous | H2O | G, L, TG, H, TL, CL | E | [14] |
spray/single droplet | selexol, rectisol, water | CO2 | TL, P, ab | absorption rate concentration | [15] |
spray bed (regenerator) | glycerol solution | H2O | LH, Tw, G | removal rate latent heat ratio ε | [17] |
falling film absorber | TEG | H2O | G, L, Tw, TL | COP | [18] |
falling film absorber | limestone slurry | SO2 | pH, CL | ε | [19] |
falling film absorber | LiCl | H2O | G, H, W | humidity ratio concentration | [20] |
membrane contactor | LiCl | H2O | me | ε | [21] |
membrane contactor | LiCl | H2O | H, CL, G/L | ε, removal rate cooling capacity COP | [22] |
hollow fiber membrane contactor | diethanolamine solution | CO2 H2S | G, Cf, Fw, hM | recovery selectivity | [23] |
Type (Absorber Type) | Correlation | Dimensionless Group for Fluid Property | Reference |
---|---|---|---|
dimensionless correlation (falling film) | Sh = 4.513 × 10−3·α·Re1.56Sc0.33 | Re, Sc | [20] |
dimensionless correlation (spray bed) | Re, Sc | [13] | |
dimensionless correlation (spray bed) | Re, Sc | this study | |
dimensionless correlation (packed bed) | , α = 0.00104 for metal pall rings, α = 0.00473 for metal IMTP, α = 0.0084 for sheet metal structured packing | Re, Sc | [24] |
dimensionless correlation (packed bed) | Re, Sc | [25] | |
dimensionless correlation (rotating packed bed) | Re, Gr | [11] | |
dimensionless correlation (spray bed) | (winter) | none | [14] |
(summer) | none | ||
without considering dimension (structured packed bed) | none | [10] | |
without considering dimension (spray bed) | none | [17] |
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Wu, H.-T.; Chung, C.-C. Effects of Vapor Pressure of Desiccant Solution on Mass Transfer Performance for a Spray-Bed Absorber. Processes 2021, 9, 1517. https://doi.org/10.3390/pr9091517
Wu H-T, Chung C-C. Effects of Vapor Pressure of Desiccant Solution on Mass Transfer Performance for a Spray-Bed Absorber. Processes. 2021; 9(9):1517. https://doi.org/10.3390/pr9091517
Chicago/Turabian StyleWu, Hung-Ta, and Chin-Chun Chung. 2021. "Effects of Vapor Pressure of Desiccant Solution on Mass Transfer Performance for a Spray-Bed Absorber" Processes 9, no. 9: 1517. https://doi.org/10.3390/pr9091517