Airflow network

The terms zonal model and flow element are also used for the simplified characterization of the flow field in a single enclosure. There, a zone represents a partial volume of air in the enclosure, whereas in the multizone models described here, a zone represents a specific enclosure which is connected to other enclosures by air conductances (see The Airflow Network later). 

The airflow network (Fig. 11.41 is composed of nodes, interconnected by links, representing individual airflow paths. Internal nodes represent the individual zones of the building, and external nodes represent faqade locations, related to a specific set of wind pressure coefficients. Each link represents a specific airflow conductance type. 

Walton, G.N. 1989. AIRNEJ-A Computer Program for Building Airflow Network Modeling. NISTIR 4072. National Institute of Standards and Technology, Gaithersburg, MD. 

The factory is modeled as a two-zone network with door, horiztmtally pivoted windows, and roof shed windows as airflow elements. The extract tan and the duct and hood are modeled as additional airflow elements. Wind pressure coefficient data are taken from literature for a simple rectangular buihl-ing shape surrounded by buildings of equal height. 

The ventilation model is a simple flow network with one zone and the different openings modeled as airflow links from the hall to outside Fig. 11.52). For the flow through the roof hood, two additional nodes were considered between the different cross-sections through which the air flows (Fig, 11.53). 

One such study details the effects of temperature variation on substrate and metabolite concentration predictions, and used an artificial neural network creating a nonlinear multivariate model to improve concentration predictions. Another study notes the effects of temperature on the mid-infrared spectral data as well, but also noted that the sensor was not affected by reactor operating conditions such as agitation, airflow and backpressure. ... 

Several special terms are used to describe traditional reaction engineering concepts. Examples include yield coefficients for the generally fermentation environment-dependent stoichiometric coefficients, metabolic network for reaction network, substrate for feed, metabolite for secreted bioreaction products, biomass for cells, broth for the fermenter medium, aeration rate for the rate of air addition, vvm for volumetric airflow rate per broth volume, OUR for 02 uptake rate per broth volume, and CER for C02 evolution rate per broth volume. For continuous fermentation, dilution rate stands for feed or effluent rate (equal at steady state), washout for a condition where the feed rate exceeds the cell growth rate, resulting in washout of cells from the reactor. Section 7 discusses a simple model of a CSTR reactor (called a chemostat) using empirical kinetics. 

Practically, in the process of outburst, the quantity of gas released is changing. Correspongdingly, flow in the network is consequentially a dynamic process. It can be said that dynamics is the basic feature of the state of flow after outburst. Therefore, it is very necessary to consider the dynamic feature of airflow when analyzing airflow catastrophic induced by gas pressure. 

Circuits airflow pressure balance equation is still tenable to dynamic network flow. Press differences between the first note and the last note can be obtained one dimensional unsteady-state flow momentum equation. For easy analysis, assuming that branch a, branch b and branch c has the same section area. 

Chen, C.Y., 2010. Numerical simulation on airflow effects in local ventilate network of gas explosion [D] Huainan Anhui university of science and technology. (In Chinese)... 

FIGURE 14.34 Solar-assisted indirect drying system for alfalfa (a) scheme of system (b) reduced mass flow network model of the fluid (c) reduced mass flow network model of the airflow system. 

In the available investigations on a potash mine ventilation system (De Souza 2006), the features of airflow were analyzed and the barriers of the ventilation network were identified. The work by Tiley authors was to detail the conveyance motion with the criterion to avoid collision between conveyances or between conveyance and shaft. Based on the running clearance... 

Damage assessment—The process nsed to appraise or determine the number of injuries and deaths, damage to public and private property, and the status of key facilities and services such as hospitals and other healthcare facilities, fire and police stations, commnnication networks, water and sanitation systems, utilities, and transportation netwoiks resulting from a man-made or natural disaster. Damper—Control that varies airflow through an air inlet, outlet, or duct. 

Building ventilation networks are systems that serve multiple locations. The common practice of arbitrarily adjusting the dampers or baffles to accommodate complaints from one area must be avoided. By changing the airflow in one area, the system balance is shifted and distribution throughout the entire network is affected. If there are distribution complaints, a test of the building s air-handhng system should be performed to confirm that the HVAC system and distribution network are in balance and are adequate. 

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