technical development program 2017 -...

Copyright © Carrier Corp. 2005

Technical Development Program 2017

Carlos MartinezRegional Sales Manager

COMMERCIAL HVAC DIVISION


History of Innovation and Education

www.williscarrier.com

www.siglers.com/about//


Sigler Presenters

Omar Rojas Ray Chow, P.E. Joseph MoralesUniversity of Notre Dame University of Wisconsin – Madison University of California - San Diego

Jed de la Cruz Rod Valdez Colby FischerUniversity of California-Riverside University of Illinois at Urbana–Champaign Cal Poly Pomona


Carrier PresentersMichael Ho, PE, LEED APCarrier Corp.Business Development/ Engr. ManagerKansas State University

Stephanie Kadow- LEED APCarrier VRF DivisionCommercial Sales ManagerSan Diego State University


Schedule


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• Enjoy and send feedback to:

Carlos Martinez

[email protected]

Section 1 – Introduction


COMMERCIAL HVAC EQUIPMENTFans in Variable

Air VolumeSystems

PRESENTED BY:

Michael Ho

Technical Development Program

Version 1.2


MenuSection 1 Introduction

Section 2 Fan Impact

Section 3 Fan Types Used in VAV Systems

Section 6 Fan Volume Control

Section 7 Fan Stability

Section 8 VFD Energy Savings in VAV Systems

Section 9 VAV Fan Control Trackingand Pressurization

Section 10 Summary

Section 4 Centrifugal Fans

Section 5 Axial Fans


SECTION 1

Introduction

FANS IN VARIABLE

AIR VOLUME SYSTEMS


Objectives• Understand the impact of fan regulation

• Identify the types of fans used in VAV

• Discuss previous and current methods offan volume control

• Utilize fan curves to demonstrate stablefan selections

• Compare fan volume control methods forenergy savings

• Discuss fan static pressure control,tracking, and pressurization



Variable Air Volume (VAV) System

SystemComponents:1. VAV Box with

Heating Coil2. Zone Thermostat3. Supply Diffuser4. Return Grille5. Duct Static

Pressure Sensor6. Supply Fan VFD7. Air Handler8. Supply Duct

Zone 1 Zone 2 Zone 3 Zone 4



SECTION 2

Fan Impact

FANS IN VARIABLEAIR VOLUME SYSTEMS


Impact of Riding the Fan Curve

Designsp

Designcfmcfm

Stat

icPr

essu

re

ED

CB

A

B1

D1C1

E1

Possible Problems• Excessive duct pressure

• Excessive duct leakage

• Excessive sound levels

• Erratic VAV terminal control

• Little or no energy savings

• Possible fan instability

Forward-Curved Fan

Section 2 – Fan Impact


SECTION 3

Fan Types Used in VAV Systems



Centrifugal FansAir is discharged at a right angle to fan shaft

Scroll or Fan Housing

Section 3 – Fan Types Used in VAV Systems


Plenum FansSingle-width, single-inlet airfoil impeller design,

for mounting inside a cabinet



Axial (In-Line) FansAir is discharged parallel to the fan shaft



SECTION 4

Centrifugal Fans



Centrifugal Fan Construction and TerminologyBlast Area Outlet

Discharge

ImpellerWheel

RimShroudWheel RingWheel ConeInlet RimWheel Rim

Inlet CollarInlet SleeveInlet Band

BearingSupport

InletInlet ConeInlet BellInlet FlareInlet NozzleVenturi

Blades

BackplateHub DiskHubplateWebplate

Double-WidthDouble-Inlet Wheel(DWDI)

Outlet Areafor DuctConnection

Housingor Scroll

HousingSide Sheet

Section 4 – Centrifugal Fans


Forward-Curved Wheel Design

Characteristics:• Most commonly used wheel in HVAC• Light weight – low cost• Operates at static pressures up to 5 in. wg max• 24 to 64 blades• Low rpm (800 to 1200 rpm)

Rotation

Tip

Heel



• Overloading type fan– Horsepower will continue to

rise with increased cfm andcan overload the motor

Forward-Curved Centrifugal Fan CharacteristicsS

tatic

Pre

ssur

e

cfm

TypicalForward-Curvedrpm Line

Fan Horsepower

Dip



Characteristics:• Blades are curved away from direction of rotation• Static pressure up to 10 in. wg• 8 to 18 blades• High rpm (1500 to 3000 rpm)

Airfoil Wheel Design

Rotation



Airfoil Centrifugal Fan Characteristics

• Non-overloading– Horsepower will peak and

begin to drop off

Typical Airfoil rpmLine

Fan Horsepower

Sta

ticP

ress

ure

cfm



Characteristics:• Single-Width, Single-Inlet (SWSI)• Operate at static pressures up to 10 in. wg• Best application with limited space or

when multiple duct discharge is desired

Fan WheelGuard

Inlet Cone

Plenum Fan Characteristics

Plenum fans without cabinets



Plenum Fans With CabinetsInlet Cone SWSI Plenum Fan Wheel

Fan Cabinet



SECTION 5

Axial Fans



• Use for high cfm applications

• In-line space savers with no cabinet

• Often used in industrial AC and ventilation applications

• Impeller similar to prop fans but blades are more aerodynamic

• Often used for return fans in AC applications

Axial (In-Line) Fans

PropellerType Impeller

Section 5 – Axial Fans


Axial Impeller Design

• Axial Wheel– Air discharged parallel to the shaft– Air is often redirected via straightening

vanes making the fan a vane axial

Section 5 – Axial Fans


SECTION 6

Fan Volume Control



Fan Volume Control Methods• Controllable Pitch Axial Fan

• Modudrive®

• Discharge Damper

• System Bypass

• “Riding the Fan Curve”– No Volume Control

• Inlet Guide Vanes (IGV)

• Variable Frequency Drive (VFD)

• Eddy Current Coupling

Section 6 – Fan Volume Control


Controllable Pitch Axial Fan



Modudrive®

• Airfoil orforward-curved fans

• Airflow modulationcontrolled by pulleyadjustment



Discharge Damper Installation

Forward-Curved Fan

Dampers are typically mounted close to or right off the fan discharge.

Remote DuctStatic Pressure

Sensor

DischargeDamper

SP



Discharge Damper Characteristics

Legend- rpm - bhp MSE - Max Static Eff. SC -System Curve RP - Rated Point = 15,000

rpm = 1010 bhp = 17.8 Class II Max. rpm = 1217rpms (*100, L to R): 3 4 5 6 7 8 9 10 11 12 13bhps (L to R): 3 5 7.5 10 15 20 25 30 40Note: Shaded Area – Recommended Operating RangeMP – Minimum Point (VAV Applications) = 7,500 cfm

Airflow (1000 cfm)

Tota

lSta

ticP

ress

ure

(in.w

g)A

B3 5 7.5


Adjusted System Curve


System BypassConstant Volume Rooftop

Variable Volume and Temperature System Application

Rooftop Fancfm is constant

Direct ConnectedBypass Damper

BackdraftDamper




rpm = 1010 bhp = 17.8 Class II Max. rpm = 1217rpms (*100, L to R): 3 4 5 6 7 8 9 10 11 12 13bhps (L to R): 3 5 7.5 10 15 20 25 30 40Note: Shaded Area – Recommended Operating Range

System Bypass Fan CharacteristicsRP = 15,000 cfm

NO FAN cfmREDUCTION

OCCURS

15 20

Airflow (1000 cfm)

Tota

lSta

ticP

ress

ure

(in.w

g)A



Riding the Fan Curve

Airflow

Sta

ticP

ress

ure

Dcfm

Dp

Reduced cfmresulting frompart load

Design orrated point (RP)




rpm = 1010 bhp = 17.8 Class II Max. rpm = 1217rpms (*100, L to R): 3 4 5 6 7 8 9 10 11 12 13bhps (L to R): 3 5 7.5 10 15 20 25 30 40Note: Shaded Area – Recommended Operating RangeMP – Minimum Point (VAV Applications) = 7,500 cfm

Riding the Fan Curve Characteristics“Wasted Static”is absorbed by

terminalsA

B 3 5 7.5

Airflow (1000 cfm)

Tota

lSta

ticP

ress

ure

(in.w

g)



% Air flow Airflow(cfm)

Fan StaticPressure*

SystemStatic

Pressure**

Fan Static Pressureminus SystemStatic Pressure

bhp*** % bhp****

100% 15,000 4.0 4.0 0 17.8 100%90% 13,500 4.15 3.24 0.91 15.7 88%80% 12,000 4.25 2.56 1.96 13.3 75%70% 10,500 4.3 1.96 2.34 12.0 67%60% 9,000 4.25 1.44 2.81 9.81 55%50% 7,500 4.15 1.0 3.15 8.0 45%

Discharge Dampers and Riding the Fan Curve

* Fan static pressure is from the fan curve** System static is determined using the second fan law*** bhp is from the fan curve**** % bhp is the percent as compared to the maximum bhp



% Air flow Airflow (cfm) bhp % bhp

100% 15,000 17.8 100%

90% 13,500 15.7 88%

80% 12,000 13.3 75%

70% 10,500 12.0 67%

60% 9,000 9.81 55%

50% 7,500 8.0 45%

Discharge Dampers and Riding the Fan Curve



Inlet Guide Vanes Configuration

Actuator Shaft(actuator not

shown)

Fan BearingLube Line for

Bearing

Inlet Vanes



Inlet Guide Vanes bhp ChartEffect of Inlet Guide Vane Position on bhp

Airfoil Centrifugal Fan Horizontal Draw-Thru

cfm (x 1000)

Bra

keH

orse

pow

er(P

erce

ntof

Max

) SC



Inlet Guide Vane Static Pressure ChartEffect of Inlet Guide Vane on Static Pressure

cfm (x 1000)

Stat

icPr

essu

re(P

erce

ntof

Max

)

SC

Airfoil Centrifugal Fan Horizontal Draw-Thru



Variable Frequency Drive

USER INTERFACE



Eddy Current Coupling

1. Eddy Current Coupling

2. Fan Motor

3. Special Cabinet Extension(as required to accommodateeddy current coupling)



Legend- rpm - bhp MSE - Max. Static Eff. SC -System Curve RP - Rated Point

rpm = 2210 bhp = 18.8 Class II Max. rpm = 2442rpms (*100, L to R): 8 10 12 14 16 18 20 24 26bhps (L to R): 3 5 7.5 10 15 20 25 30 40Note: Shaded Area – Recommended Operating RangeMP – Minimum Point (VAV Applications) = 7500 cfm

Airflow (1000 cfm)

Tota

lSta

ticP

ress

ure

(in.w

g)

Speed Control Using a VFD

3 5



Fan Modulation Methods

% Air flow Airflow(cfm)

SystemStatic

Pressure*Fan rpm

VFDbhp**VFD

% bhp***VFD

% bhpDischarge

Dampers andRiding the Fan

Curve

100% 15,000 4.0 2210 18.8 100% 100%

90% 13,500 3.525 2000 14.1 75% 88%

80% 12,000 3.1 1810 10.8 57% 75%

70% 10,500 2.725 1625 7.6 40% 67%

60% 9,000 2.4 1475 5.9 31% 55%

50% 7,500 2.125 1300 4.1 22% 45%

* System static is determined using the second fan law** bhp is from the fan curve*** % bhp is the percent as compared to the maximum bhp



Fan Modulation Methods

% Design Airflow

Riding the Fan Curve

Inlet GuideVanes

%D

esig

nbh

p

VFD Speed Control


Discharge Dampers


SECTION 7

Fan Stability



Typical VAV VFD Fan CharacteristicsFull cfm =15,000 (RP)

Min. cfm =7500 (MP)

Section 7 – Fan Stability

Legend- rpm - bhp MSE - Max. Static Eff. SC -System Curve RP - Rated Point

rpm = 2210 bhp = 18.8 Class II Max. rpm = 2442rpms (*100, L to R): 8 10 12 14 16 18 20 24 26bhps (L to R): 3 5 7.5 10 15 20 25 30 40Note: Shaded Area – Recommended Operating RangeMP – Minimum Point (VAV Applications) = 7500 cfm

Airflow (1000 cfm)

Tota

lSta

ticP

ress

ure

(in.w

g)


Input Screen VAV Fan



Manual Plot of System Curve

% cfm cfm System and FanStatic Pressure (in. wg)

100 15,000 4.090 13,500 3.52580 12,000 3.170 10,500 2.72560 9,000 2.450 7,500 2.125

System Cooling Design: 15,000 cfmSystem Static Pressure: 4 in. wgMinimum Airflow: 7,500 cfmMinimum Static Pressure Set Point: 1.5 in. wg



SECTION 8

VFD Energy Savings in VAV Systems



The three fan laws state:• Airflow varies directly

with the fan speed

• Static pressure varies as thesquare of the fan speed

VFD Energy Savings

Section 8 – VFD Energy Savingsin VAV Systems

Horsepower varies as the• Horsepower varies as thecube of the fan speed


SECTION 9

VAV Fan Control, Tracking,and Pressurization



VAV Fan Control

Section 9 – VAV Fan Control, Tracking,and Pressurization

1/2 to 2/3 Duct Length


Supply and Return Fan – VAV System

ReturnDamper

Constant airflowdifferential ismaintainedbetween supplyand return fans.


ExhaustDamper

OutdoorDamper


Supply – Exhaust Fan VAV System

Inside SpacePressure Sensor

0.05 in. wg

Outside ReferencePressure Sensor

ReturnDamper

The insidespace pressuresensor, controlsthe exhaust fan tomaintain slightpositive pressure.


ExhaustDamper

OutdoorDamper


SECTION 10

Summary



Summary

• Explained the impact of fan regulation• Identified the types of fans used in VAV• Examined previous and current methods of

fan volume control• Utilized fan curves to demonstrate stable

fan selections• Compared fan volume control methods for

energy savings• Examined fan static pressure control,

tracking, and pressurization

Section 10 – Summary


Work Session

Work Session

FANS IN VAV SYSTEMS

Work Session1. True or False? The drive losses in an eddy current coupling are less than that in a VFD.

____________________

2. Which fan type is best for VAV applications and why?__________________________________________________________________________________________________________________________________________________

3. True or False? VAV systems have the ability to track changes in building loads.____________________

4. Which method of volume control is the most cost effective and efficient?____________________

5. Discharge dampers are used with which type of fan?


Technical Development Program

Thank YouThis completes the presentation.

TDP-613 Fans in Variable Air Volume SystemsArtwork from Symbol Library used by permission ofSoftware Toolboxwww.softwaretoolbox.com/symbols

technical development program 2017 -...

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