| 1. |
- Wang, W., et al.
(författare)
-
Carbon dioxide adsorption thermodynamics and mechanisms on MCM-41 supported polyethylenimine prepared by wet impregnation method
- 2015
-
Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 142, s. 221-228
-
Tidskriftsartikel (refereegranskat)abstract
- Amine-functionalized sorbents prepared by wet impregnation method shows great promises for CO2 capture from real flue gas in power plants. The objective of this work is to understand CO2 adsorption thermodynamics and mechanisms at varied polyethylenimine (PEI) loadings on mesoporous MCM-41 by wet impregnation method using a computational approach for the first time. The structures of PEI/MCM-41 sorbents were optimized using molecular dynamics (MD), and the CO2 adsorption thermodynamics at varied PEI loadings was simulated using Grand Canonical Monte Carlo (GCMC) method. Results showed a good agreement between experiments and simulation. On the surface of the MCM-41, there are high CO2-philic sites for CO2 adsorption, which were firstly covered by PEI molecular. The functionalization groups increased the interactions of the CO2 with more PEI molecular deployed on the surface of the MCM-41, then to the center of the pore. The adsorption performance of the composite sorbents depended on the adsorption cites and the space for CO2 diffusion. The CO2 adsorption thermodynamics and mechanisms at varied PEI loadings shed lights on tuning CO2 capture performance with amine-functionalized sorbents for power plant greenhouse gas control.
|
|
| 2. |
- Yang, J., et al.
(författare)
-
COMPOSITE SUPPORTED LIQUID MEMBRANE CONTAINING MIMIC ENZYME FOR CO2 CAPTURE
- 2019
-
Ingår i: Energy. Proc.. - : Scanditale AB.
-
Konferensbidrag (refereegranskat)abstract
- Current technologies for capturing carbon from flue gas are plagued by high capital, energy and chemical costs, etc. Here, we report a composite supported liquid membrane containing mimic enzyme that may provide a possible solution to these issues. This composite membrane has two highly permeable silicone layers which immobilize the mimic enzyme (Zn-cyclen complex) solution in the pores of a cellulose acetate nanofiltration membrane. The schematic is showed in Fig.1. The membrane couples the selectivity of liquid sorbents and energy-efficiency of membrane separation without absorbent regeneration unit. The prepared Zn-cyclen complex was characterized by1HNMR and dissociation constant (pKa). The contact angles of the cellulose acetate support membrane and the prepared composite membrane were tested. CO2 separation performances of the membranes were studied in a plate-and-frame membrane module system. The membrane system presents a CO2/N2 selectivity of 94 and a CO2 permeance of 1.33 [m3 (STP)/(m2 bar h)] with a very small amount of 0.0052 M mimic enzyme. This composite supported liquid membrane shows the advantages of low cost, simple production procedure and high CO2 separation performance.
|
|
| 3. |
- Wang, K., et al.
(författare)
-
Amended soils with weathered coal exhibited greater resistance to aggregate breakdown than those with biochar : From the viewpoint of soil internal forces
- 2024
-
Ingår i: Soil & Tillage Research. - : Elsevier B.V.. - 0167-1987 .- 1879-3444. ; 244
-
Tidskriftsartikel (refereegranskat)abstract
- Soil erosion is the first threat to soil functions. Reducing the soil aggregate breakdown strength is a key step to improve the soil's ability to resist rainfall splash erosion. Soil internal forces have been found to be the initial and important forces driving aggregate turnover. The application of exogenous organic materials can effectively improve soil aggregate stability and the resistance to rainfall erosion of agricultural soils. However, from the perspective of soil internal forces, information about the reduction effects of the exogenous organic materials application on soil aggregate breakdown is scarce, especially in comparing the effects of different materials. In this study, weathered coal and biochar were individually applied to loamy clay soil at rates of 0 %, 1 %, 2 %, and 3 % (w/w). Soil internal forces, aggregate breakdown strength, and splash erosion rate of different amended soils were then examined after four years. The results showed that compared with unamended soils (0 %), both weathered coal and biochar applications clearly increased the van der Waals attractive pressure and thus decreased the positive net pressure between soil particles. Additionally, these materials reduced soil aggregate breakdown strength and splash erosion rate. The application effects of the two materials were increased with their application rates. Under a lower electrolyte concentration in soil solution (0.0001 mol L−1), the aggregate breakdown strength in the soils amended with weathered coal was lower than that with biochar by 9.6 %, 23.2 %, and 17.7 % (when the diameter of broken aggregate was < 10 μm) and by 10.3 %, 20.8 %, and 17.5 % (when the diameter of broken aggregate was < 20 μm) at the 1 %, 2 %, and 3 % application rates, respectively (P < 0.05). Additionally, soils amended with weathered coal exhibited lower splash erosion rates compared to those amended with biochar, particularly at the higher application rate of 3 %. From the viewpoint of soil internal forces, weathered coal appears to be a suitable exogenous organic material for improving soil aggregate stability and anti-erosion ability during rainfall events. Our findings provide valuable insights into utilizing exogenous materials to improve soil resistance to rainfall splash erosion, assisting agricultural soil management in areas frequently affected by rainfall erosion.
|
|
| 4. |
- Wang, W., et al.
(författare)
-
Numerical simulation study on discharging process of the direct-contact phase change energy storage system
- 2015
-
Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 150, s. 61-68
-
Tidskriftsartikel (refereegranskat)abstract
- The mobilized thermal energy storage system (M-TES) has been demonstrated as a promising technology to supply heat using waste heat in industries to distributed users, where heat discharging determines whether M-TES system can satisfy the required heating rate. The objective of this work is to investigate the solidification mechanism of phase change materials (PCM) for heat discharging in a direct-contact thermal energy storage (TES) container for M-TES. A 2-dimensional (2D) numerical simulation model of the TES tank is developed in ANSYS FLUENT, and validated with the experimental measurement. Effects of flow rate and inlet temperature of heat transfer oil (HTO) were studied. Results show that (a) the discharging process includes the formation of solidified PCM followed by the sinking of solidified PCM; (b) the discharging time of M-TES can be reduced by increasing the flow rate of heat transfer oil. When the flow rate is increased from 0.46m3/h to 0.92m3/h, the solidified PCM is increased from 25vol.% to 90vol.% within 30min; (c) the discharging time can be reduced by decreasing the inlet temperature of HTO. While the inlet temperature is reduced from 50°C to 30°C, the solidified PCM is increased from 60vol.% to 90vol.% within 30min. This work provides engineering insights for the rational design of discharging process for M-TES system.
|
|
| 5. |
|
|
| 6. |
- Yang, Xiaohu, et al.
(författare)
-
Comparison of direct numerical simulation with volume-averaged method on composite phase change materials for thermal energy storage
- 2018
-
Ingår i: Applied Energy. - : Elsevier Ltd. - 0306-2619 .- 1872-9118. ; 229, s. 700-714
-
Tidskriftsartikel (refereegranskat)abstract
- Melting heat transfer in open-cell metal foams embedded in phase-change materials (PCMS) predicted by the volume-averaged method (VAM) was systematically compared with that calculated using direct numerical simulation (DNS), with particular attention placed upon the contribution of natural convection in the melt region to overall phase change heat transfer. The two-temperature model based on the assumption of local thermal non-equilibrium was employed to account for the large difference of thermal conductivity between metallic ligaments and PCM (paraffin). The Forchheimer extended Darcy model was employed to describe the additional flow resistance induced by metal foam. For the DNS, a geometric model of metal foam based on tetrakaidehedron cells was reconstructed. The DNS results demonstrated significant temperature difference between ligament surface and PCM, thus confirming the feasibility of local thermal non-equilibrium employed in VAM simulations. Relative to the DNS results, the VAM combined with the two-temperature model could satisfactorily predict transient solid-liquid interface evolution and local temperature distribution, although pore-scale features of phase change were lost. The presence of natural convection affected significantly the melting front shape, temperature distribution and full melting. The contribution of natural convection to overall phase change heat transfer should be qualitatively and quantitatively given sufficient consideration from both macroscopic (VAM) and microscopic (DNS) point of views. Besides, practical significance and economic prospective using metal foam in TES unit for WHR system to provide residential heating or hot water is discussed and analyzed.
|
|
| 7. |
|
|
| 8. |
- Yu, J., et al.
(författare)
-
Effect of porous media on the heat transfer enhancement for a thermal energy storage unit
- 2018
-
Ingår i: CLEANER ENERGY FOR CLEANER CITIES. - : Elsevier. ; , s. 984-989
-
Konferensbidrag (refereegranskat)abstract
- Thermal energy storage (TES) can effectively recover thermal energy from low-temperature waste heat and it has now been received increasing attentions in practical engineering applications. Nevertheless, the relatively low thermal conductivity of engineering available phase change materials (PCMs) greatly limits the energy efficiency of TES applications. To enhance the phase change process, open-cell metal foam with a porosity of 0.94 and pore density of 15 PPI (pore per inch) was employed to be inserted either in heat transfer fluid (HTF) or in phase change material (PCM). A two-dimensional axis-symmetric problem was numerically solved and was validated through comparing temperature history at selected points. Results demonstrated that the involvement of open-cell metal foam can effectively enhance the phase change heat transfer, greatly reducing the full melting time. By comparing the four cases (without metal foam, inserting metal foam into HTF, PCM and both domains), the case that both HTF and PCM domains were embedded with porous media can provide the best heat transfer enhancement, from which practical applications with thermal engineering may benefit.
|
|
| 9. |
- Andreae, Christina, 1969-, et al.
(författare)
-
Changes in Appetite During the Heart Failure Trajectory and Association With Fatigue, Depressive Symptoms, and Quality of Life
- 2021
-
Ingår i: Journal of Cardiovascular Nursing. - : Lippincott Williams & Wilkins. - 0889-4655 .- 1550-5049. ; 36:6, s. 539-545
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Decreased appetite can contribute to malnutrition in patients with heart failure (HF). Little is known about the trajectory of appetite over time in patients with HF and the factors associated with decreased appetite after discharge from the hospital.OBJECTIVE: The aims of this study were to investigate changes in appetite over time and explore how fatigue, depressive symptoms, and quality of life are associated with decreased appetite.METHODS: Data from the multicenter randomized Coordinating study evaluating Outcomes of Advising and Counseling in Heart Failure were used. Logistic regression and mixed-effects logistic regression were used to investigate changes in appetite over time and to explore the relationship between appetite and fatigue, depressive symptoms, and quality of life.RESULTS: A total of 734 patients with HF (mean age, 69 years) were included. Decreased appetite was present at all follow-up measurements; however, decreased appetite was significantly lower at the 1-month (odds ratio [OR], 0.43; confidence interval [CI], 0.29-0.63), 6-month (OR, 0.31; CI, 0.20-0.47), 12-month (OR, 0.22; CI, 0.14-0.34), and 18-month (OR, 0.24; CI, 0.15-0.37) follow-ups compared with baseline. Decreased appetite was associated with fatigue (OR, 3.09; CI, 1.98-4.84), depressive symptoms (OR, 1.76; CI, 1.35-2.29), and low quality of life (OR, 1.01; CI, 1.01-1.02) across all measurement points adjusted for covariates.CONCLUSIONS: Appetite improved after discharge; however, at all time points, at least 22% of patients reported decreased appetite. Fatigue, depressive symptoms, and low quality of life are factors associated with decreased appetite. Decreased appetite is a long-standing problem in that it does not disappear spontaneously after an acute HF deterioration.
|
|
| 10. |
|
|
