Modeling of a Rotary Adsorber for Continuous Capture of Indoor Carbon Dioxide

Removing indoor CO2 as a pollutant via solid sorbents is a promising solution to maintaining acceptable indoor air quality while minimizing the energy consumption of ventilation. Compared to fixed-bed and fluidized-bed configurations, which require at least two beds to allow for continuous operation, a rotary adsorber is more compact and suitable to be integrated into the ventilation systems of buildings. In the present study, a regenerative rotary adsorber based on temperature swing adsorption was modeled to investigate continuous CO2 capture in an indoor environment. The governing equations of heat and mass transfer processes associated with the capture were established and coded in ANSYS Fluent software. The spatiotemporal variations of CO2 concentration and temperature in gas and solid phases within the rotary adsorber were obtained. The key findings are: (1) adjusting the speed mainly affects circumferential concentration and temperature distribution, but has little impact on axial concentration and temperature; (2) Increasing desorption inlet flow rate has little impact on adsorption outlet concentration, but significantly decreases desorption outlet concentration; (3) Raising desorption inlet temperature can increase both adsorption and desorption outlet average concentrations; (4) Reducing the volume proportion of the desorption sector will slightly increase adsorption outlet concentration and slightly decrease desorption outlet concentration, but barely affects average adsorption and desorption outlet temperatures

Explore the Benefits of Natural Air: New Insights from Field and Chamber Tests on Cognitive Performance

Exposure to natural environments has a range of health benefits, including enhancing psychological restoration and cognitive development. While there are various explanations on the causes for the benefits of the natural exposure, such as less air pollution and noise, more physical activity, stronger social interactions, or even more diverse microbial community, etc., this study has zeroed in on the air quality of the natural environment. In addition to low-level pollution, what makes the natural air superior remains unclear. To this end, we conducted a series of psychological evaluation and cognitive tests on a couple of subjects in a national forest park in southwest China. Based on the results, we built an artificial chamber where selected air parameters can be independently manipulated and carried out similar tests in the chamber. We came to the following conclusion. (1) Exposure to real natural environment demonstrated tangible benefits for cognitive performances and mental states and the benefits can be obtained to some extent in the artificial environment by creating air qualities similar to the air in the natural environment. (2) Scents in natural environments may be one of the key beneficial factors. (3) Adopting proper cognitive test is critical for distinguishing the differences made by the natural exposure. Working memory showed marked responses to the natural exposure

Explore the Benefits of Natural Air: New Insights from Field and Chamber Tests on Cognitive Performance

Exposure to natural environments has a range of health benefits, including enhancing psychological restoration and cognitive development. While there are various explanations on the causes for the benefits of the natural exposure, such as less air pollution and noise, more physical activity, stronger social interactions, or even more diverse microbial community, etc., this study has zeroed in on the air quality of the natural environment. In addition to low-level pollution, what makes the natural air superior remains unclear. To this end, we conducted a series of psychological evaluation and cognitive tests on a couple of subjects in a national forest park in southwest China. Based on the results, we built an artificial chamber where selected air parameters can be independently manipulated and carried out similar tests in the chamber. We came to the following conclusion. (1) Exposure to real natural environment demonstrated tangible benefits for cognitive performances and mental states and the benefits can be obtained to some extent in the artificial environment by creating air qualities similar to the air in the natural environment. (2) Scents in natural environments may be one of the key beneficial factors. (3) Adopting proper cognitive test is critical for distinguishing the differences made by the natural exposure. Working memory showed marked responses to the natural exposure

A Comprehensive Review of Recent Progress on GaN High Electron Mobility Transistors: Devices, Fabrication and Reliability

GaN based high electron mobility transistors (HEMTs) have demonstrated extraordinary features in the applications of high power and high frequency devices. In this paper, we review recent progress in AlGaN/GaN HEMTs, including the following sections. First, challenges in device fabrication and optimizations will be discussed. Then, the latest progress in device fabrication technologies will be presented. Finally, some promising device structures from simulation studies will be discussed