barcode generator source code in javascript Design Procedures: Part 6 272 Eight in Software

Encoder QR Code ISO/IEC18004 in Software Design Procedures: Part 6 272 Eight

Design Procedures: Part 6 272 Eight
Encode QR Code JIS X 0510 In None
Using Barcode generator for Software Control to generate, create QR Code JIS X 0510 image in Software applications.
Denso QR Bar Code Recognizer In None
Using Barcode recognizer for Software Control to read, scan read, scan image in Software applications.
Figure 856 Three-duct multizone damper sequence
QR Code ISO/IEC18004 Printer In Visual C#
Using Barcode printer for VS .NET Control to generate, create QR Code JIS X 0510 image in VS .NET applications.
Encoding QR Code JIS X 0510 In .NET Framework
Using Barcode drawer for ASP.NET Control to generate, create QR-Code image in ASP.NET applications.
Dual-duct air-handling system
QR Code 2d Barcode Creator In Visual Studio .NET
Using Barcode drawer for VS .NET Control to generate, create QR image in .NET applications.
Print QR In VB.NET
Using Barcode creation for VS .NET Control to generate, create Quick Response Code image in .NET applications.
The dual-duct system (Fig 857) operates on the same principles as the multizone system, but the hot and cold plenums are extended through the building, with a mixing box provided at each zone A common arrangement (not shown) has a single fan supplying both ducts That arrangement has the same reheat problems as the twoduct multizone system The two-fan system shown in Fig 857 overcomes most problems and provides very economical operation The warm return air goes almost entirely to the hot duct, minimizing the use of heating energy Outside air goes almost entirely to the cold duct, minimizing the use of cooling energy Each fan is provided with volume control, based on maintaining a constant static pressure in its related duct Exterior zones, which may need some heating, are provided with mixing boxes Interior zones, which need only cooling, are provided with VAV boxes (see below) This system may be made even more economical by the use of variable volume mixing boxes (Fig 858a and b) The VAV mixing box utilizes separate operators for the hot and cold dampers, allowing them to function independently and sequentially as follows At maximum heating, the hot damper is fully open, the cold damper closed As the heating load decreases, the hot damper modulates toward closed, and air volume decreases When it is about 60 percent closed, the cold damper starts to open and total air volume remains stable
EAN-13 Generator In None
Using Barcode maker for Software Control to generate, create EAN-13 image in Software applications.
Making USS Code 39 In None
Using Barcode printer for Software Control to generate, create Code 3 of 9 image in Software applications.
Downloaded from Digital Engineering Library @ McGraw-Hill (wwwdigitalengineeringlibrarycom) Copyright 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website
Create Barcode In None
Using Barcode creation for Software Control to generate, create barcode image in Software applications.
UPC Symbol Encoder In None
Using Barcode creator for Software Control to generate, create UPC Symbol image in Software applications.
Design Procedures: Part 6
USS-128 Drawer In None
Using Barcode creator for Software Control to generate, create EAN / UCC - 13 image in Software applications.
Code 128 Code Set A Printer In None
Using Barcode creator for Software Control to generate, create Code 128C image in Software applications.
Downloaded from Digital Engineering Library @ McGraw-Hill (wwwdigitalengineeringlibrarycom) Copyright 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website
OneCode Generator In None
Using Barcode creator for Software Control to generate, create USPS OneCode Solution Barcode image in Software applications.
UPC-A Creator In None
Using Barcode creation for Font Control to generate, create Universal Product Code version A image in Font applications.
Figure 857 Double-duct two-fan air-handling system
Generating GS1 DataBar Expanded In Java
Using Barcode generator for Java Control to generate, create GS1 DataBar Expanded image in Java applications.
Encoding Data Matrix 2d Barcode In None
Using Barcode generator for Font Control to generate, create Data Matrix image in Font applications.
Design Procedures: Part 6 274 Eight
Creating ANSI/AIM Code 39 In None
Using Barcode creator for Online Control to generate, create Code 3/9 image in Online applications.
Create Code 128C In Java
Using Barcode encoder for Java Control to generate, create Code 128 image in Java applications.
Figure 858 Double-duct VAV mixing box
Code-128 Printer In None
Using Barcode generation for Word Control to generate, create Code 128 image in Word applications.
EAN / UCC - 13 Generation In Objective-C
Using Barcode encoder for iPad Control to generate, create GS1 - 13 image in iPad applications.
The hot damper continues to close and is fully closed when the cold damper is 40 percent open The cold damper can continue on to fully open, if required, with a corresponding increase in air volume When variable volume is used, the outside and return air dampers must be controlled to maintain minimum ows as described in Sec 851
Downloaded from Digital Engineering Library @ McGraw-Hill (wwwdigitalengineeringlibrarycom) Copyright 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website
Design Procedures: Part 6 Design Procedures: Part 6 275
Variable-volume air-handling system
The VAV system (Fig 859) is based on the principle of matching the load by varying the air volume supplied to each zone rather than varying the temperature, with the intent of saving fan work energy as compared with a constant-volume system As the individual VAV boxes modulate in response to zone demands, the total system volume will vary If the fan volume is not controlled, the static pressure in the duct system will increase, resulting in noise, lack of control at the boxes, and the possibility of duct blowout To overcome this, several methods of volume control are available In many cases, the controlled variable is the static pressure in the duct at some point selected to provide suf cient pressure at the most remote VAV box An old rule of thumb is to locate the sensor two-thirds to three-fourths of the distance from the fan to the most remote box In reality, the best location is from the inlet duct to the most remote box If this point is satis ed, all other points in the system will be satis ed Complete building DDC systems allow every box condition to be monitored, which allows the total cfm requirements to be summed and the fan speed adjusted accordingly Volume control methods include: A modulating damper at the fan discharge This makes the fan ride up its curve and saves little, if any, fan work energy A bypass from supply to return, with a modulating damper This means that the fan is working at constant volume at all times, while system volume varies Good control is obtained, but there are no energy savings Inlet vane dampers As these dampers modulate, they change the operating characteristic of the fan (see Chap 4) and energy is saved Inlet vanes pose an energy penalty as an added resistance to air ow A cone, which can be moved in and out at the fan inlet to vary the ow, has a similar effect on the inlet vane damper Mechanical variable-speed drives As described in Sec 8333, these systems save energy because of the physical law which states that the fan (or pump) horsepower varies as the cube of the speed This savings is not fully realized because of mechanical losses in the systems Electronic (solid-state) variable-frequency speed controllers As described in Sec 8333, variable-frequency drives are used for fans, pumps, and chiller compressors One of the largest of such systems is used with a 5000-hp motor driving a chiller compressor at the Dallas-Fort Worth airport Energy use varies as the cube of the speed, although there are some losses in the electric circuits
Downloaded from Digital Engineering Library @ McGraw-Hill (wwwdigitalengineeringlibrarycom) Copyright 2004 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website
Copyright © OnBarcode.com . All rights reserved.