Air Quality Constraints Research Articles

Unlocking ventilation flexibility of large airport terminals through an optimal CO2-based demand-controlled ventilation strategy

Large airport terminals consume significant energy due to their extensive ventilation demands. Optimizing the operation of ventilation systems is a crucial aspect of achieving greater energy flexibility and efficiency. In this study, we proposed an optimal CO2-based demand-controlled ventilation (DCV) strategy that utilizes the large indoor space of airport terminals to shift ventilation loads, reduce operating cost, and enable demand response (DR) programs. The effect of air infiltration on ventilation demand is considered in the DCV strategy through on-site CO2 measurement. A passenger dwell model is integrated to estimate the occupancy of airport terminal based on flight schedules for dynamic ventilation control. Considering the DR signal and time-of-use tariff, an advanced evolutionary algorithm is employed to locate optimal ventilation solutions that deliver better economic performance and energy flexibility while meeting indoor air quality constraints. Using an airport terminal in Beijing, China, as a testbed, the superior performance of the proposed DCV strategy was demonstrated against a baseline strategy with a fixed outdoor air supply rate under three scenarios. Simulation results showed that the proposed DCV strategy can reduce peak energy consumption by up to 60.9% and operating costs by up to 48.6% in different scenarios. Moreover, the DCV strategy can provide a flexible trade-off between the overall energy efficiency and DR capability in the adjustable DR scenario. This study revealed great opportunities for improving the flexibility of ventilation in large-space buildings and provided an instructive case study.

Evaluating the potential role of federal air quality standards in constraining applications of prescribed fire in the western United States

Prescribed fire is a useful tool for building resilient landscapes in fire-prone areas across the globe. In the western U.S., prescribed fire is employed by federal, state, and Tribal land managers and planned during particular meteorological and air quality conditions to manage air quality impacts. As agencies prepare to plan and permit more prescribed fire, an ongoing question will be whether existing air quality conditions constrain the potential for more prescribed fire. We performed a set of spatial and statistical analyses to evaluate how prescribed burns are potentially constrained by federal air quality standards. In doing so, we also examined if the answers to these questions differed when applied to different land management agencies that administer prescribed burns in the West. Analysis of the results shows that the geographic distribution of air quality conditions has not been constraining the implementation of prescribed fire plans, and climate change-driven changes to air quality, such as increasing ozone levels, may make prescribed burning more difficult under current air quality constraints. Furthermore, results demonstrated regional air quality issues for specific pollutants, suggesting an ongoing need for regional air quality assessments in the planning of prescribed burning across the western U.S.

Indoor Environmental Quality assessment of mixed-mode ventilation with ceiling fans in the tropics

Mixed-mode ventilation in buildings has a potential for significant energy savings. However, previous attempts in the tropics were unsuccessful due to the hot and humid weather. Indeed, there is little to no natural ventilation potential in tropical climates if conventional air conditioning systems are used. Additionally, existing studies typically do not consider the noise and air quality constraints while the performance of mixed-mode buildings is susceptible to outdoor conditions. Using elevated air movement has proven to be an effective strategy to offset the rise in the room temperature setpoint without sacrificing occupants’ thermal comfort as it helps dissipate body heat through the convective cooling effect. Hence, this study aims at investigating the total indoor environment quality (IEQ) performance of mixed-mode ventilation operations with various air speeds based on tropically acclimatized subjects. To this end, a testbed was designed and constructed in Singapore, consisting of a variable air volume (VAV) system, ceiling fans with continuous speed control, personal ventilation (PV) desks, and plenum acoustic windows. Five operating modes have been tested: fully air-conditioned (AC) mode using VAV alone, hybrid air conditioned (AC+PV) mode using VAV and PV desks, concurrent ventilation (CV) mode using PV desks with the windows partially opened, natural ventilation (NV) mode with the windows fully opened, and acoustic natural ventilation (Acoustic NV) mode with the windows partially opened. 57 subjects were invited to the experiment and asked to complete a comprehensive IEQ survey under 16 different indoor conditions, which are combinations of these operating modes and air speeds ranging from 0.10 to 1.15 m/s. Experiment results show that NV and CV in Singapore can achieve more than 90% thermal acceptability with adequate air movement. More importantly, the median standard effective temperature (SET*) for thermal neutrality is approximately 3°C higher when operating in NV as compared to AC+PV or CV modes, indicating adaptation even when the modes switches are within the same day.

Simulation of total coal consumption control under air quality constraints based on machine vision

Simulation of total coal consumption control under air quality constraints based on machine vision

Statistical testing of availability for mining technological systems with air quality constraints

AbstractWe develop a mining technology statistical model showing that even environmentally sustainable mining can be still very profitable. We put constraints on mining activities for elevated levels of particulate matters (eg, PM2.5 and PM10) in the air. We show that upper quantiles (eg, 95%) of productivity slightly decrease with respect to maximal number of failures, and this high‐productivity feature is robust with respect to variation of underlying statistical parameters. We illustrate the model on two currently active mining sites, the Chuquicamata copper mine in Chile and the opencast coal mine Libouš in the Czech Republic. Two generic working scenarios have been obtained. We show that, under very realistic conditions for both countries, the Czech Republic and Chilean mining companies can regulate mining activities for high thresholds of air pollutants without a substantial loss of productivity. Sensitivity analysis with respect to parameters is provided.

An Integrated Air Quality Model and Optimization Model for Regional Economic and Environmental Development: A Case Study of Tangshan, China

ABSTRACTAn interval programming optimization model was formulated to develop effective and feasible regional economic structure adjustment plan using Tangshan Municipality in China as a case study. The optimization model was coupled with a WRF-CAMx-PSAT air quality simulation system through the estimated industrial emission sensitivity coefficients and equivalent coefficients for PM2.5 concentrations. Seven categories of industries were examined, and the results indicated that industries with higher emission sensitivity coefficients should be given priority for control. The effectiveness of the obtained optimal schemes was further assessed by the air quality simulation system. It indicated that PM2.5 concentrations in Tangshan would decrease by [33.5%, 39.3%] than those in 2013. This study provided an effective method framework for industries to maximize profits while meeting certain air quality constraints under uncertainty through the coupling of air quality simulation and optimization models.

Design and Performance Analysis of a CD Nozzle for Evacuating Emissions from the Subway Tunnels

Tunnels have very severe air quality constraints that typically require good ventilation system. The process of removing air from any space by mechanical means is known as evacuation. Evacuation of exhaust and smoke in case of fire emergencies is very necessary to bring in fresh air as it leads to pressure and temperature build up which causes discomfort to the passengers travelling especially in long tunnels. Generally, in longitudinal ventilation, a jet blower fan enclosed in a cylindrical casing is used for ventilation. These jet fans accelerate the air by imparting it an impulse in the desired direction. The main aim is to optimize the design and replace the jet blower fan cylindrical enclosure by a CD Nozzle. The suction fan along with rotor is exactly placed at the throat of the nozzle. The modeling is done using CATIA V5 software and CFD flow and modal analysis is carried out using ANSYS V 15.0. Various parameters like pressure, temperature, density, humidity and mass flow rate of air are measured and compared with the conventional model by experimentation and the results are validated.

Energy Storage Technologies: The Past and the Present

With the recent advances in the field of applications which require a certain power level over a short period of timeand with the air-quality constraints which have become more stringent in the last few decades, the energy storagesystems (ESSs) have come to play a crucial role for the electric grid. Various aspects such as the historical evolutionof ESSs, technical characteristics, and applications for the ESSs are thoroughly addressed. Special emphasis is given tothe interaction between the smart grid (SG) and microcrogrids applications, on the one hand, and the ESSs, on the otherhand. Thus, the main goal of this work is to present the specialist and nonspecialist review of the most important ESSscurrently available on the market.

Fragments of Regionalism: The Limits of Southern California Governance

ABSTRACT:This paper explores the manifestations of regional governance in Southern California. The author evaluates whether three regional public authorities, empowered to address areawide transportation and air quality constraints, fragment or integrate regional identity and vision. He examines the lessons of the Southern California experience for other US regions engaged in government reorganization. He argues that Southern California regionalism constitutes a shadow governance characterized by technical bias, single purpose compartmentalization, and institutional insularity. He concludes that the affiliation of regional planning with single purpose and systems maintenance functions has facilitated regionalism at the same time it has limited its potential by functionally fragmenting and submerging the regional public interest.

Real-time urban power dispatch with ambient air quality constraints

A power dispatch methodology for urban utility company facing ambient air quality constraints is developed. This approach consists of (1) a real-time air dispersion model for the urban area and its surrounding region, (2) a fuel minimization procedure which will generate a schedule to satisfy the demand and the constraints on pollution concentration. Forecast meteorological data and ambient air quality information are assumed available for the procedure.

Real-Time Urban Power Dispatch with Ambient Air Quality Constraints

A power dispatch methodology for urban utility company facing ambient air quality constraints is developed. This approach consists of 1) a real-time air dispersion model for the urban area and its surrounding region, 2) a fuel minimization procedure which will generate a schedule to satisfy the demand and the constraints on pollution concentration. Forecast meteorological data and ambient air quality information are assumed available for the procedure.

Optimal dispatch of electric power with ambient air quality constraints

A method is given for allocating power loads for a system of electric generating units in a way which meets the time-dependent demand and minimizes the sum of the fuel cost and a penalty function for pollution. The method takes into account explicitly the dynamic nature of ambient air pollution which depends on the topography of a region and on the past performance of the system. With suitable and reasonably realistic approximations, the problem is reduced to a linear-quadratic optimal control problem for which a linear feedback control rule is obtained. In addition, a discrete version of the problem is given which has the form of a quadratic programming problem, and thus can accommodate, in a straightforward manner, additional constraints such as fuel limitations and upper bounds on emission.