Zone Air Research Articles

Investigation of energy storage with considering paraffin discharging through a wavy duct

Simulation of paraffin freezing has been carried out with employing numerical technique. The unit has various layers of PCM and air. The selected PCM is RT30 and to intensify the thermal features, Al2O3 nano-particles were dispersed. Several passages for air were inserting along the sinusoidal PCM layers. Air gets the heat which is produced from solidification and its temperature rises. The warm air at outlet can be used for ventilation of a room. With reduction of liquid paraffin with augmenting time, the amount of heat reduces and temperature of air reduces. Entropy generation for various amount of concentration of NEPCM (φ) and amplitude of wavy layer (a) were depicted in contours. With augment of a, the velocity of air augments about 26.8% to 78% due to reduction of available space in air zone. When a=20mm, dispersing nano-powders leads to reduction of irreversibility (Sgen) about 1.775% and 20.779% when t= 30 and 150min. With augment of amplitude, Sgen augments about 61.57% at t=30min while it declines about 42.95% when t=150min.

Experimental study of the temperature distribution and water evaporation in an axial dual-zone vortex chamber spray dryer

The use of an axial dual-zone vortex chamber for spray drying applications is experimentally studied, focusing on water spray evaporation. In the hot zone of the vortex chamber, hot air (maximum 300 °C) is fed; in the cold zone, mild temperature (80 °C) air. The spray nozzle is installed in the hot feed air zone, in the cylindrical wall of the vortex chamber and injects the water radially toward the center line of the chamber. In spray drying applications, the generated flow and temperature field should allow a fast initial drying of the droplets in the hot zone, followed by rapid evacuation of the particles that are formed to the cold zone where final drying takes place and particles can be evacuated. A slightly different design of the hot and cold zone vortex chambers aims at intensifying the axial motion. Experiments with detailed temperature measurements during dry operation and with injection of a water spray are combined to gain insight in the spray penetration and deflection, the motion of the hot and cold air in the vortex chamber and the resulting temperature profile, and water evaporation and its effect on the temperature profile. A two-fluid nozzle is used and the influence of the hot air inlet temperature, the air flow rate, the water flow rate and the droplet size studied, as well on the temperature profile as on the evaporation capacity. The experimental data allow a first evaluation of the concept.

Fracturing behaviors of soil subjected to monotonic and fatigue pneumatic loading

The mechanical behaviors of soil exposed to monotonic and cyclic pneumatic loading are investigated through laboratory testing. The fracture morphology, air pressure, and earth pressure (EP) were monitored and analyzed. In monotonic pneumatic fracturing, pressure of air is the crucial factor that determines the length and number of fractures. In cyclic pneumatic fracturing, the number and propagation of fractures is greater than that under the monotonic loading, as well as the disturbance zone of the pressurized air to the soil. It is found that high-frequency injection maintains higher air pressure inside the soil, coupled with the cyclic loading, the fatigue fracturing effect is much better than that under monotonic loading. The patterns of fractures subjected to monotonic and cyclic loading are presented. It is concluded that the higher the injection frequency and air pressure, the larger the number and propagation range of fractures.

Healthcare-associated infection impact with bioaerosol treatment and COVID-19 mitigation measures

BackgroundThe real-world impact of breathing zone air purification and coronavirus disease 2019 (COVID-19) mitigation measures on healthcare-associated infections is not well documented. Engineering solutions to treat airborne transmission of disease may yield results in controlled test chambers or single rooms, but have not been reported on hospital-wide applications, and the impact of COVID-19 mitigation measures on healthcare-associated infection rates is unknown.AimTo determine the impact of hospital-wide bioaerosol treatment and COVID-19 mitigation measures on clinical outcomes.MethodsThe impact of the step-wise addition of air disinfection technology and COVID-19 mitigation measures to standard multi-modal infection control on particle counts, viral and bacterial bioburden, and healthcare-associated infection rates was investigated in a 124-bed hospital (>100,000 patient-days over 30 months).Findings and conclusionThe addition of air disinfection technology and COVID-19 mitigation measures reduced airborne ultrafine particles, altered hospital bioburden, and reduced healthcare-associated infections from 11.9 to 6.6 (per 1000 patient-days) and from 6.6 to 1.0 (per 1000 patient-days), respectively (P<0.0001, R2=0.86). No single technology, tool or procedure will eliminate healthcare-associated infections, but the addition of a ubiquitous facility-wide engineering solution at limited expense and with no alteration to patient, visitor or staff traffic or workflow patterns reduced infections by 45%. A similar impact was documented with the addition of comprehensive, restrictive, and labour- and material-intensive COVID-19 mitigation measures. To the authors' knowledge, this is the first direct comparison between traditional infection control, an engineering solution and COVID-19 mitigation measures.

A flexible and generic functional mock-up unit based threat injection framework for grid-interactive efficient buildings: A case study in Modelica

Grid-interactive efficient buildings (GEBs) have been considered as an important asset to support the power grid reliability by utilizing the demand flexibility offered by GEBs. GEBs are enabled by advances in sensors and controls, and the communication between building equipment, whole buildings, and the grid. The integration of different building technologies and network-based communication system makes GEBs vulnerable to passive threats such as equipment failure and active threats such as cyber-attacks. Modeling and simulation is an effective way to evaluate the impact of threats on the system performance. This paper proposes a generic and flexible threat injection framework for commonly-used building energy simulators such as EnergyPlus and Modelica to support threat modeling and evaluation. This framework leverages functional mock-up unit (FMU) to develop a general modeling interface for threat injection and simulation. A numerical case study using Modelica as a building energy simulator is conducted to demonstrate the capability of the framework for supporting single/multiple-order threat modeling and simulation of a GEB. Four threats and their combinations are injected on a Modelica-based threat-free building energy and control system, including operating supply fan at its full speed, remotely cycling the chiller on and off, blocking the chiller from receiving the chilled water supply temperature setpoints, and hijacking the global zone air temperature setpoint. Simulation results show that the cyber-attack that leads to short-term signal blocking has small effects on the system operation due to the “self-healing” feature of the heating, ventilation, and air-conditioning (HVAC) interactive control system. The threat that takes control of resetting the global zone air temperature setpoints has the most adverse impact on the system energy use, peak power demand, thermal comfort and the provision of demand flexibility. The combination of four threats have aggregative effects on the system but the effects are less than the additive effects of the individual threat.

Taking a deep breath: a qualitative study exploring acceptability and perceived unintended consequences of charging clean air zones and air quality improvement initiatives amongst low-income, multi-ethnic communities in Bradford, UK

BackgroundPoor air quality is the one of the biggest causes of early death and illness across the lifespan. In the UK, 28 local authorities with illegal pollution levels have been mandated by the Government to develop plans to rapidly reduce pollution to legal limits. These plans include consideration of implementing one of four of charging 'Clean Air Zone’ (CAZ) classes in areas of high pollution which would charge older polluting vehicles a daily charge to enter. While this offers a potential to improve air quality, the extent to which CAZ might impact (for example, economically) on socio-economically deprived groups and local businesses is unclear.AimsTo explore the acceptability and perceived unintended consequences of a CAZ and other initiatives to improve air quality with seldom-heard communities living in deprived, multi-ethnic areas within the city of Bradford, UK.MethodsTen semi-structured focus groups were conducted with people who live in areas of high pollution and deprivation. A total of 87 people participated from a diverse range of ethnic backgrounds with the majority of Pakistani origin. Recorded data were transcribed, coded and analysed using thematic analysis.FindingsAs poor air quality was not always visible it was seen as a hidden issue by many, and not prioritised over other more visible environmental issues (e.g. fly-tipping, littering). There was resistance to proposals which included charging private vehicles. Many felt that low-income families did not have the resources to purchase compliant vehicles or pay daily charges, placing a disproportionate burden on them. It was also felt that low-income taxi drivers would be disproportionately affected financially by proposals. Public transport infrastructure was felt to be inadequate. Other traffic management or emission reduction activities were also explored. Views towards these initiatives were more positive if they did not directly affect individuals financially.ConclusionAir quality initiatives such as CAZs were felt to be likely to financially disadvantage communities already living in socio-economic and environmental poverty. Policy makers need to carefully consider appropriate mitigation strategies to ensure that health and economic inequalities are not increased by implementation of CAZ. Given air quality is low priority for some groups, careful engagement and communication will be required to increase acceptance interventions such as CAZs.

Evaluating the Impact of a Wall-Type Green Infrastructure on PM10 and NOx Concentrations in an Urban Street Environment

Nature-based solutions can represent beneficial tools in the field of urban transformation for their contribution to important environmental services such as air quality improvement. To evaluate the impact on urban air pollution of a CityTree (CT), an innovative wall-type green infrastructure in passive (deposition) and active (filtration) modes of operation, a study was conducted in a real urban setting in Modena (Italy) during 2017 and 2018, combining experimental measurements with modelling system evaluations. In this work, relying on the computational resources of CRESCO (Computational Centre for Research on Complex Systems)/ENEAGRID High Performance Computing infrastructure, we used the air pollution microscale model PMSS (Parallel Micro-SWIFT-Micro SPRAY) to simulate air quality during the experimental campaigns. The spatial characteristics of the impact of the CT on local air pollutants concentrations, specifically nitrogen oxides (NOx) and particulate matter (PM10), were assessed. In particular, we used prescribed bulk deposition velocities provided by the experimental campaigns, which tested the CT both in passive (deposition) and in active (filtration) mode of operation. Our results showed that the PM10 and NOx concentration reductions reach from more than 0.1% up to about 0.8% within an area of 10 × 20 m2 around the infrastructure, when the green infrastructure operates in passive mode. In filtration mode the CT exhibited higher performances in the abatement of PM10 concentrations (between 1.5% and 15%), within approximately the same area. We conclude that CTs may find an application in air quality hotspots within specific urban settings (i.e., urban street canyons) where a very localized reduction of pollutants concentration during rush hours might be of interest to limit population exposure. The optimization of the spatial arrangement of CT modules to increment the “clean air zone” is a factor to be investigated in the ongoing development of the CT technology.

Fast simulation and high-fidelity reduced-order model of the multi-zone radiant floor system for efficient application to model predictive control

Model predictive control, as the most popular intelligent advanced control technology in recent years, is increasingly applied to building air conditioning systems to achieve adaptive and energy-efficient operation of the system, however, model predictive control imposes higher requirements on the computational efforts of the model. In this research, a complex coupled heat transfer model of the increasingly popular radiant floor system is analyzed and a full-order model of the radiant floor is developed. Then, after controllability and observability analysis, a fast high-fidelity reduced-order model that can accurately characterize the dynamic thermal performance of the original model is proposed applying the balanced truncation method. The accuracy of the reduced-order model was verified by comparing the radiant floor surface temperature, return water temperature, zone air temperature, and unheated average internal surface temperature with experimental test results, the TRNSYS model, and the full-order model. The computation time of the reduced-order model for open-loop simulation was reduced by 86% to 98% compared to the TRNSYS model. More importantly, the reduced-order model can effectively reduce the complexity of the model predictive control, resulting in a 38% to 78% saving in computation time compared to the full-order model, significantly improving computational efficiency and enhancing the robustness of the model predictive control.

Numerical and Experimental Investigations on Performance Optimization of a Microturbojet Engine Combustor

Sudden extinction of a microturbojet engine combustor was encountered during the engine accelerating process, which motivates the present work to optimize the combustor performance. Numerical results show that by decreasing the primary zone air-introducing area and increasing the dilution zone air-introducing area, the primary zone air percentage is reduced from 39.35% to 32%, and the primary zone excess air ratio is reduced from 1.122 to 0.915, which is believed to be beneficial for flame stability both in terms of residence time and rich burn. Meanwhile, the vortex flow pattern in the primary zone varies little as the variations of the airflow distribution. The new engine, which is equipped with the optimized combustor, is tested by experiments. The successful accelerating to the rotating design speed demonstrates the effectiveness of combustor optimization work.

How Can Floor Covering Influence Buildings’ Demand Flexibility?

Although the thermal mass of floors in buildings has been demonstrated to help shift cooling load, there is still a lack of information about how floor covering can influence the floor’s load shifting capability and buildings’ demand flexibility. To fill this gap, we estimated demand flexibility based on the daily peak cooling load reduction for different floor configurations and regions, using EnergyPlus simulations. As a demand response strategy, we used precooling and global temperature adjustment. The result demonstrated an adverse impact of floor covering on the building’s demand flexibility. Specifically, under the same demand response strategy, the daily peak cooling load reductions were up to 20–34% for a concrete floor whereas they were only 17–29% for a carpet-covered concrete floor. This is because floor covering hinders convective coupling between the concrete floor surface and the zone air and reduces radiative heat transfer between the concrete floor surface and the surrounding environment. In hot climates such as Phoenix, floor covering almost negated the concrete floor’s load shifting capability and yielded low demand flexibility as a wood floor, representing low thermal mass. Sensitivity analyses showed that floor covering’s effects can be more profound with a larger carpet-covered area, a greater temperature adjustment depth, or a higher radiant heat gain. With this effect ignored for a given building, its demand flexibility would be overestimated, which could prevent grid operators from obtaining sufficient demand flexibility to maintain a grid. Our findings also imply that for more efficient grid-interactive buildings, a traditional standard for floor design could be modified with increasing renewable penetration.

Energy and cost assessment of packaged ice energy storage implementations using OpenStudio Measures

As renewable portfolio standards enforce the expansion of renewables on the U.S. grid in the coming years, old storage technologies must be re-evaluated for a dynamic, interactive future grid. Ice thermal storage, traditionally for diurnal load shifting on large central chiller plants, is also viable in packaged devices for most buildings that lack central plants. However, modeling of these unitary thermal storage systems (UTSS) has been very limited to-date. To help make packaged thermal storage modeling more accessible, this paper presents a recently developed OpenStudio measure for rapid analysis of UTSS. Using this measure, we assess the UTSS implementation in new and retrofit retail buildings with both packaged single zone air conditioners (PSZAC) and packaged variable air volume (PVAV) systems. Each implementation is evaluated on annual energy use, fan energy use, load shifting efficiency, daily unused ice availability, and potential cost savings under various time-of-use rates. Deficiencies with schedule-based control are highlighted by comparing the daily unused ice and the cooling-electricity load duration curve. Annual energy use increases by 1.2–3.7%, but on-peak electric demand is reduced by 32.2–36.6%.

Evaluation of biomarkers of heat stress using automatic health monitoring system in dairy cows

The aim of this study was to evaluate biomarkers of heat stress (HS) from an automatic milking system (AMS), the relationships between measurements of the temperature-humidity index (THI), reticulorumen pH and temperature, and some automatic milking systems parameters in dairy cows (rumination time (RT), milk traits, body weight (BW) and consumption of concentrate (CC)) during the summer period. Lithuanian Black and White dairy cows (n=365) were selected. The cows were milked with Lely Astronaut® A3 milking robots with free traffic. Biomarkers were collected from the Lely T4C management program for analysis. The pH and temperature of the contents of the cow reticulorumen were measured using specific Smax-tec boluses. The farm zone's daily humidity and air temperature were obtained from the adjacent weather station (2 km away). According to this study, during HS, the higher THI positively cor- relates with milk lactose (ML), which increases the risk of mastitis and decreases CC, RT, BW, MY, reticulorumen pH, and F/P. Some biomarkers of HS can be milk yield, milk lactose, somatic cell count, concentrate intake, rumination time, body weight, reticulorumen pH, and milk fat - protein ratio. We can recommend monitoring these parameters in the herd management program to identify the possibility of heat stress.

Dust Capturing Capacity of Woody Plants in Clean Air Zones throughout Taiwan

To exploit the ability of vegetation to capture particulate matter (dust) from the air and improve air quality, 546 clean air zones (CAZs) consisting of various types of urban green space have been established in Taiwan. This study systematically assessed the pollutant filtering efficiency of tree species planted in these green spaces. This research aims to provide quantitative data on individual trees’ dust retention functions for future green space planning in urban areas. Field surveys were conducted in 98 CAZs throughout Taiwan. The vegetation composition of approximately 14,000 woody trees, consisting of 210 species, was surveyed. The vegetation surveyed showed that the dominant species in many CAZs in southern Taiwan were introduced species. The dust capturing capacity of the tree species was found to be positively correlated with leaf size. However, the amount of dust retention was affected mainly by the surface structure and morphological characteristics of the leaves, such as a rough, hairy surface. Among the tree species, Spathodea campanulata, Pterocarpus indicus, and Delonix regia exhibited the best dust capture and retention capacity in southern Taiwan, and Ficus macrocarpa, Alstonia scholaris, and Melia azedarach were the most desirable dust retention species. The results suggest that native evergreen species are suitable for dust retention in urban green spaces.

Reflective Meta-Films with Anti-Damage Property via Field Distribution Manipulation

The reflective optical multi-films with high damage thresholds are widely used in intense-light systems. Metasurfaces, which can manipulate light peculiarly, give a new approach to achieve highly reflective films by a single-layer configuration. In this study, reflective metasurfaces, composed of silicon nanoholes, are numerically investigated to achieve high damage thresholds. These nanoholes can confine the strongest electric field into the air zone, and, subsequently, the in-air electric field does not interact directly with silicon, attenuating the optothermal effect that causes damage. Firstly, the geometrical dependencies of silicon nanoholes’ reflectance and field distribution are investigated. Then, the excitation states of electric/magnetic dipoles in nanostructures are analyzed to explain the electromagnetic mechanism. Furthermore, the reflection dependences of the nanostructures on wavelength and incident angle are investigated. Finally, for a typical reflective meta-film, some optothermal simulations are conducted, in which a maximum laser density of 0.27 W/µm2 can be handled. The study provides an approach to improve the laser damage threshold of reflective nanofilms, which can be exploited in many intense-light applications.

Evaluation of a four-zone indoor exposure model for predicting TCPP concentrations in a low-energy test house

The Indoor Environmental Concentrations in Buildings with Conditioned and Unconditioned Zones (IECCU) model was developed by the United States Environmental Protection Agency to predict indoor exposures. This study evaluated IECCU by comparing airborne tris(1-chloro-2-propyl) phosphate (TCPP) concentrations measured over five years in a test house to IECCU predictions. IECCU inputs included building environment (air zone configuration, airflow rates and temperature), source (spray polyurethane foam (SPF)) and sink (gypsum and wallboard) parameters, and simulation conditions. Simulations were conducted using three sets of inputs. Simulation 1 and 2 differed in using quantified versus design inputs for temperatures and airflows. Simulation 1 and 3 differed in air zone configuration. Given the best available inputs (Simulation 1), IECCU predicted basement concentrations were generally higher but within three times of the measured values. The basement prediction/measurement ratios for all three simulations ranged from 0.5 to 8.3 (average: 2.9), while the predicted living zone concentrations were generally lower but within ten times of the measurements. The design inputs of Simulation 2 resulted in greater discrepancy between and predictions and measurements than the quantified inputs of Simulation 1. Simulation 2 also did not capture diurnal variation as well as Simulation 1. Comparisons of Simulation 1 and 2 demonstrate the importance of modeling with accurate temperatures and airflows. Furthermore, a sensitivity analysis indicates that to improve IECCU prediction for TCPP emission from SPF, efforts are needed to accurately measure SPF mass transfer parameters, especially the SPF/air partition coefficient and the initial TCPP concentration in SPF.

Development of a three-zone combustion model for stratified-charge spark-ignition engine

A thermodynamic model for calculating the operating process in the cylinder of a spark-ignition engine with internal mixture formation and stratified air-fuel charge based on the volume balance method was developed. The model takes into account the change in the working fluid volume during the piston movement in the cylinder. The equation of volume balance of internal mixture formation processes during direct fuel injection into the engine cylinder was compiled. The equation takes into account the adiabatic change in the volume of the stratified air-fuel charge, consisting of fuel-air mixture volume and air volume. From the heat balance equation, the change in the fuel-air mixture volume during gasoline evaporation in the fuel stream and from the surface of the fuel film due to external heat transfer was determined. Basic equations of combustion-expansion processes of the stratified air-fuel charge were derived, taking into account three zones corresponding to combustion products, fuel-air mixture and air volumes. The equation takes into account the change in the working fluid volume due to heat transfer and heat exchange between the zones and the walls of the above-piston volume. Dependences for determining the temperature in the three considered zones and pressure in the cylinder were obtained. Graphs of changes in the volumes of the combustion products, fuel-air mixture and air zones with the change of the above-piston volume in partial load modes (n=3,000 rpm) were plotted. With increasing load from bmep=0.144 MPa to bmep=0.322 MPa, at the moment of fuel ignition, the volume of the fuel-air mixture increases from 70 % to 92 % of the above-piston volume. At the same time, the air volume decreases from 30 % to 8 %. Analysis of theoretical and experimental indicator diagrams showed that discrepancies in the maximum combustion pressure do not exceed 5 %

Computer simulation of moisture transfer in walls: impacts on the thermal performance of buildings

ABSTRACT In order to reduce electricity consumption in buildings, it is imperative to improve their thermal performance. Due to the many variables involved in thermal processes computer simulation is a consolidated method for thermal analysis. However, in many energy efficiency analyses calculus of heat conduction through the dwelling envelope does not consider moisture transportation and storage. The objective of this work was to evaluate the impacts of moisture transfer in walls on the thermal performance of naturally ventilated and artificially conditioned buildings using EnergyPlus computer simulation. This research contributed to the literature by showing the difference in thermal zone air humidity, temperature and annual energy demand (i.e. electricity consumption) when moisture effects are considered in walls. Buildings were composed of masonry and solid concrete envelopes and three numerical models were simulated: Conduction Transfer Function Model (CTF), Effective Moisture Penetration Depth Model (EMPD) and Combined Heat and Moisture Transfer Model (HAMT). The CTF model does not consider moisture effects. Results found a higher relative air humidity for the studied thermal zone by applying the HAMT model in the numerical simulation, and the envelope porosity was proven to affect HAMT humidity results. Comparing the HAMT and EMPD models with the CTF model, the annual energy demanded for cooling presented a 21% reduction for the EMPD model in the masonry and 9% increase for the HAMT model in the solid concrete. This article shows the importance of an accurate EnergyPlus heat transfer model for simulating a whole building to check edification attendance of minimum comfort parameters and select envelope materials aiming the reduction of electricity consumption.

Humidity-Dependent Survival of an Airborne Influenza A Virus: Practical Implications for Controlling Airborne Viruses

Relative humidity (RH) can affect influenza A virus (IAV) survival. However, the mechanism driving this relationship is unknown. We hypothesized that the RH-dependent survival of airborne IAV could be predicted by the efflorescence/deliquescence divergent infectivity (EDDI) hypothesis. We determined three distinct RH response zones based on the hygroscopic growth factor of carrier aerosols. These zones were classified as the super-deliquescence zone (RH > 75%), the hysteresis zone (43% < RH < 75%), and the sub-efflorescence zone (RH < 43%). We added IAV (H3N2) to protein-enriched saline and aerosolized it into sub-efflorescence or superdeliquescence zone air, yielding aerosols in the effloresced or noneffloresced state, respectively. We then adjusted the RH to an ergonomically comfortable RH (60%). Fifteen minutes post-aerosolization, the surviving fractions (arithmetic means ± standard errors) of virus were higher in effloresced aerosols (9.5 ± 0.5%) than in non-effloresced aerosols (0.40 ± 0.05%). A virus suspension was also aerosolized directly into air within the super-deliquescence, hysteresis, and sub-efflorescence zones to assess the impact of the sudden change in RH from an initial 100% saturated RH to these zonal ranges. Fifteen minutes post-aerosolization, the surviving fractions were 3 ± 0.4%, 2 ± 0.1%, and 12 ± 2%, respectively. Survival following gradual adaptation to the hysteresis zone RH range was sustained in effloresced and reduced in the non-effloresced aerosols. The EDDI model predicted the survival of IAV under seasonal conditions, offering strategies for controlling indoor air infection.

Meta-Deflectors Made of Dielectric Nanohole Arrays with Anti-Damage Potential

In intense-light systems, the traditional discrete optical components lead to high complexity and high cost. Metasurfaces, which have received increasing attention due to the ability to locally manipulate the amplitude, phase, and polarization of light, are promising for addressing this issue. In the study, a metasurface-based reflective deflector is investigated which is composed of silicon nanohole arrays that confine the strongest electric field in the air zone. Subsequently, the in-air electric field does not interact with the silicon material directly, attenuating the optothermal effect that causes laser damage. The highest reflectance of nanoholes can be above 99% while the strongest electric fields are tuned into the air zone. One presentative deflector is designed based on these nanoholes with in-air-hole field confinement and anti-damage potential. The 1st order of the meta-deflector has the highest reflectance of 55.74%, and the reflectance sum of all the orders of the meta-deflector is 92.38%. The optothermal simulations show that the meta-deflector can theoretically handle a maximum laser density of 0.24 W/µm2. The study provides an approach to improving the anti-damage property of the reflective phase-control metasurfaces for intense-light systems, which can be exploited in many applications, such as laser scalpels, laser cutting devices, etc.

A novel integrated rotary reactor for NO reduction by CO and air preheating: Reactor design and heat transfer modelling

Abstract An integrated reactor for NOx reduction by CO (iNA reactor) was proposed, integrating a rotary air preheater with a decoupled NOx adsorption-reduction reactor. Three zones were created in this reactor: a flue gas zone, a reducing gas zone, and an air zone. It was expected that NOx reduction efficiency could be enhanced by independently controlled temperature and oxygen content. In this paper, heat transfer was investigated for the proposed iNA reactor to understand the temperature evolution. A heat transfer model was first developed for an air preheater for verification. Energy balance equations were proposed for both the gas and the matrix phase. The modelling results showed that the design can meet the targeted temperatures. The developed heat transfer model was further applied to simulate the temperature profiles in the iNA reactor with three zones. The influences of several design and operating parameters on the heat transfer performance were investigated: flow direction of reducing gas, inlet temperature of flue gas, rotating speed of the reactor, inlet temperature and flow rate of reducing gas, and different zone partitions. It was concluded that a slower rotating speed was preferred to maintain large temperature differences between different zones, which benefited the temperature-dependent NOx adsorption-reduction process. For the reducing gas, downward flow direction, higher temperature and flow rates were preferred. The heat transfer performance was not very sensitive to zone partition ratio, although it may have an important effect on the reaction efficiencies.