Title 241054277-Hvac 6.5 MB 641
0 (Front Matter).pdf
1 (Chapter 1)
2 (Chapter 2)
3 (Chapter 3)
4 (Chapter 4)
5 (Chapter 5)
6 (Chapter 6)
7 (Chapter 7)
8 (Chapter 8)
9 (Chapter 9)
10 (Chapter 10)
11 (Chapter 11)
12 (Chapter 12)
13 (Chapter 13)
14 (Chapter 14)
15 (Chapter 15)
16 (Appendix A)
17 (Appendix B)
18 (Appendix C)
19 (Appendix D)
20 (Appendix E)
21 (Index)

##### Document Text Contents
Page 2

Heating, Ventilating, and
Air Conditioning
Analysis and Design

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Page 320

friction factor becomes independent of the Reynolds number and can be read directly
from Fig. 10-1. Also, in this regime the friction factor can be expressed by

(10-8)

Values of the friction factor in the region between smooth pipes and complete turbu-
lence, rough pipes can be expressed by Colebrook’s natural roughness function

(10-9)

The Reynolds number is defined as

(10-10)

where:

ρ = mass density of the flowing fluid, lbm/ft3 or kg/m3
µ = dynamic viscosity, lbm/(ft-sec) or (N-s)/m2
� = kinematic viscosity, ft2/sec or m2/s

The hydraulic diameter is used to calculate Re when the conduit is noncircular. Appen-
dix A contains viscosity data for water, air, and refrigerants. The ASHRAE Handbook,
Fundamentals Volume (2) has data on a wide variety of fluids.

To prevent freezing it is often necessary to use a secondary coolant (brine solution),
possibly a mixture of ethylene glycol and water. Figure 10-2 gives specific gravity and

Re = =
ρ

µ
VD VD

v

1
1 14 2 2 1

9 3

f
D e

e D f
= + − +

. log( / ) log

.

Re( / )

1
1 14 2

f
D e= +. log( / )

302 Chapter 10 Flow, Pumps, and Piping Design

Figure 10-1 Friction factors for pipe flow.

Critical
zone

Transition
zone Complete turbulence, rough pipes

0.09

0.08

0.05
0.04

0.03

0.02

0.015

0.01
0.008

0.006
0.004

0.002

0.001
00008
0.0006
0.004

0.0002

0.0001

0.00005

0.00001

0.07

0.06

0.05

0.04

0.03

0.025

0.02

0.015

0.01

0.009

0.008
103 1051042 2 3 4 5 6 8 1062 3 4 5 6 8 1072 3 4 5 6 8 1082 3 4 5 6 83 4 5 6 8

Smooth pipes

=
6

4
/R

r

Laminar
zone

F
ri

ct
io

n
f

ac
to

r
f

If

L D
V

2

2
g

=

R
el

at
iv

e
ro

u
gh

n
es

s
e/

D

(
)

= 0.000001
e
D

= 0.000005
e
D

DVp
Reynolds number Re = µ

ρ

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10-1 Fluid Flow Basics 303

Figure 10-2a Specific gravity of aqueous ethylene glycol solutions. (Adapted by permission from
ASHRAE Handbook, Fundamentals Volume, 1989.)

Figure 10-2b Viscosity of aqueous ethylene glycol solutions. (Adapted by permission from
ASHRAE Handbook, Fundamentals Volume, 1989.)

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Simulations, building, 279, 289
Single-zone systems, 29
Skin wettedness, 87
Solar absorptances, table of values, 183

altitude angle, 188
angle of incidence, 189
angles, 187
attenuation coefficients, interior, 210
azimuth angle, 189
constant, 190
data, 212
data, table, 187
declination, 188
heat gain coefficients (SHGC), 198
heat gain, absorbed, 233
surface solar azimuth, 189
time, 185
zenith angle, 189

Solubility of air in water, 330
Source elimination of contaminants, 98
Source media for space heating, 176
Space air conditioning, 65

off design, 75
Space air diffusion, 366
Space air distribution, 107
Space pressurization, 100
Special allowance factor, lights, 224
Spectral distribution of sunlight, 191
Split systems, 41
Spray chambers, 464
Spray dehumidifier, 464, 470
Stack effect, infiltration, 163
Standard atmosphere, 49
Static regain method, 450
Steam heating systems, 343
Steam, air removal from systems, 347

condensate return by gravity, 355
condensate return, 344
pipe sizing table, 353
separator, 345
sizing system components, 349
system operation, 348

table of flow rate and velocity, 350–351
traps, 346

Supply air, cooling, 273

definition, 98
for space heating, 175

Surface solar azimuth angle, 189
Surface unit conductances, table, 131
System characteristic, fluid flow, 305
System effect factors, fans, 407
System selection and arrangement, 26

T
TAB, 18

daily range, 220
dry bulb, 55
effective, 87
operative, 87
wet bulb globe, 87
wet bulb, 54

Terminal device, 36
Thermal bridge, definition, 138
Thermal comfort tool, 92
Thermal conductance, 121
Thermal conduction, 119
Thermal convection, 121
Thermal energy storage, TES, 45
Thermal properties, building materials,

123
Thermal resistance, 120
Thermal resistance, table for plane air

spaces, 133
Thermal sensation scale, ASHRAE 89
Thermal energy storage, 45
Thermodynamic wet bulb temperature,

54
Throttling range, 15
Throw, air diffuser, 367
Time value of money, 5
Tobacco smoke, 95
Total emissive power, 182

622 Index

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Total pressure, 300
Transmission heat losses, 160
Transmittance, 182
Transport coefficients inside tubes, 492
Transport coefficients outside tubes, 496
Turning vanes, 437

U
Under-floor ventilation, 374
Unit resistances for air, table, 131
Unit thermal conductance, 121
Unit thermal resistance, 120
Unit ventilators, 38
Unitary systems, 39
Units and dimensions, 3
Use factor, lights, 223

V
Valve characteristic, 333
Valve selection, 333
Variable speed drives, fans, 416
Variable-volume systems, 32
VAV fan powered terminal, 389
VAV systems, 32
Ventilation air, definition, 98
Ventilation efficiency, 112

Ventilation rate procedure, 102
Ventilation, displacement, 107
Ventilation, room systems, 374
Volatile organic compounds (VOCs), 94
Volumetric efficiency of compressors,

542

W
Walls and floors below grade, 143
Walls and roofs, heat conduction, 138
Water hammer, 344
Water systems, 37
Weather data, 212, 597
Web accessible control systems, 3
Wet bulb globe temperature, 87
Wet bulb temperature, 54
Wien’s displacement law, 182
Wind, effect on infiltration, 162
WINDOW 5.2 software, 199, 246
Windows, heat transfer coefficients, 143

Z
Zenith angle, solar, 189
Zeotropes, 539
Zone air heat balance, 249
Zone, definition, 26
Z-transform methods, 228

Index 623

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