Exercise

on

Cooling Load Calculations

by

Assist. Prof. Dr. Tul Manewattana. Chulalongkorn University

Bangkok, THAILAND

2005 ASHRAE Handbook - Fundamentals (SI) © 2005 ASHRAE, Inc.

Station Information

1b 1c 1d 1e 1f 1g 1h 1i

BANGKOK 484550 13.73N 100.57E 20 101.08 7.00 SEA 8201

Annual Heating and Humidification Design Conditions

99.6% 99% DP HR MCDB DP HR MCDB WS MCDB WS MCDB MCWS PCWD2 3a 3b 4a 4b 4c 4d 4e 4f 5a 5b 5c 5d 6a 6b

12 18.7 20.3 11.7 8.6 23.0 13.3 9.5 23.7 6.8 27.4 5.6 27.8 1.0 N/A

Annual Cooling, Dehumidification, and Enthalpy Design Conditions

DB MCWB DB MCWB DB MCWB WB MCDB WB MCDB WB MCDB MCWS PCWD7 8 9a 9b 9c 9d 9e 9f 10a 10b 10c 10d 10e 10f 11a 11b

4 7.1 35.7 26.4 35.0 26.4 34.4 26.2 28.0 33.0 27.6 32.4 27.2 31.8 2.9 N/A

DP HR MCDB DP HR MCDB DP HR MCDB Enth MCDB Enth MCDB Enth MCDB12a 12b 12c 12d 12e 12f 12g 12h 12i 13a 13b 13c 13d 13e 13f

26.7 22.4 30.2 26.4 21.9 29.9 26.1 21.6 29.7 89.5 33.0 87.9 32.8 86.4 32.1

Extreme Annual Design Conditions

1% 2.5% 5% Max Min Max Min Max Min Max Min Max Min Max Min14a 14b 14c 15 16a 16b 16c 16d 17a 17b 17c 17d 17e 17f 17g 17h

6.4 5.7 5.1 33.2 37.4 16.3 0.8 2.4 38.0 14.6 38.4 13.2 38.9 11.8 39.5 10.1

Monthly Design Dry Bulb and Mean Coincident Wet Bulb Temperatures

DB MCWB DB MCWB DB MCWB DB MCWB DB MCWB DB MCWB18a 18b 18c 18d 18e 18f 18g 18h 18i 18j 18k 18l

0.4% 33.9 24.3 34.6 24.4 35.8 24.7 36.7 25.9 36.7 26.7 35.2 26.51% 33.5 24.3 34.0 24.8 35.2 25.1 36.2 26.3 36.2 26.9 34.8 26.42% 33.0 24.3 33.5 24.9 34.7 25.4 35.8 26.5 35.7 26.9 34.2 26.4

DB MCWB DB MCWB DB MCWB DB MCWB DB MCWB DB MCWB18m 18n 18o 18p 18q 18r 18s 18t 18u 18v 18w 18x

0.4% 34.8 26.3 34.3 26.3 34.0 26.2 33.8 26.2 34.0 25.3 33.9 24.51% 34.3 26.2 33.8 26.1 33.6 26.1 33.3 26.1 33.5 25.2 33.3 24.32% 33.9 26.1 33.3 25.9 33.1 26.1 32.9 26.1 33.1 25.1 32.9 24.1

Monthly Design Wet Bulb and Mean Coincident Dry Bulb Temperatures

WB MCDB WB MCDB WB MCDB WB MCDB WB MCDB WB MCDB19a 19b 19c 19d 19e 19f 19g 19h 19i 19j 19k 19l

0.4% 26.8 30.5 27.7 32.4 27.7 32.8 28.6 34.1 28.2 33.6 27.7 32.31% 26.4 30.3 27.2 31.5 27.4 32.4 28.2 33.4 28.0 33.4 27.6 32.12% 26.1 30.2 26.9 31.0 27.2 32.0 28.1 33.1 27.7 32.9 27.3 31.7

WB MCDB WB MCDB WB MCDB WB MCDB WB MCDB WB MCDB19m 19n 19o 19p 19q 19r 19s 19t 19u 19v 19w 19x

0.4% 27.6 32.3 27.2 31.7 27.5 31.2 27.5 31.7 26.9 31.4 26.4 30.61% 27.2 31.7 27.0 31.5 27.2 31.1 27.2 31.3 26.6 31.0 25.9 30.02% 27.0 31.4 26.7 31.1 26.9 30.9 26.9 30.9 26.2 30.7 25.5 30.0

Monthly Mean Daily Temperature Range

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec20a 20b 20c 20d 20e 20f 20g 20h 20i 20j 20k 20l

8.9 7.8 7.3 7.1 6.8 6.1 6.1 6.0 6.4 6.4 7.3 8.8

WMO# World Meteorological Organization number Lat Latitude, ° Long Longitude, °Elev Elevation, m StdP Standard pressure at station elevation, kPaDB Dry bulb temperature, °C DP Dew point temperature, °C WB Wet bulb temperature, °CWS Wind speed, m/s Enth Enthalpy, kJ/kg HR Humidity ratio, grams of moisture per kilogram of dry airMCDB Mean coincident dry bulb temperature, °C MCDP Mean coincident dew point temperature, °C MCWB Mean coincident wet bulb temperature, °CMCWS Mean coincident wind speed, m/s PCWD Prevailing coincident wind direction, °, 0 = North, 90 = East

Time zonecode

Coldest month WS/MCDB0.4% 1%

Period

1a

Hours +/-UTCElevLong

n-Year Return Period Values of Extreme DB

2%

MCWS/PCWDto 0.4% DB

Standard deviation n=50 years

0.4% 1% 2%Enthalpy/MCDB

Cooling DB/MCWB

MCWS/PCWDto 99.6% DB

StdP

Humidification DP/MCDB and HR

Station name WMO#

Coldest month

Heating DB99.6%

Lat

99%

2% 0.4%Evaporation WB/MCDB

0.4% 2%1%

Dec

%Jan

Feb Mar

Feb Mar

%Aug

Jun

ExtremeMaxWB

Hottest month 1%

Extreme Annual DBMean

Dehumidification DP/MCDB and HR0.4% 1%

Extreme Annual WS

Hottestmonth

DB range

n=5 years

JunMay

n=20 yearsn=10 years

Apr May

%Jan

NovJul

Apr

Design conditions for BANGKOK, Thailand

Aug Sep Oct Nov

Dec

%Jul

Sep Oct

1111

Outdoor Design ConditionsOutdoor Design Conditions

1414

Components of Cooling LoadComponents of Cooling Load

1) External Load

2) Internal Load

3) Outdoor Air Load

1.1) Roofs

1.2) Wall

1.3) Glass (Windows)

1.4) Ceiling

1.5) Floor

1.6) Partition

2.1) People

2.2) Lights

2.3) Power

2.4) Appliances

2525

Approximate Watt/Approximate Watt/Sq.mSq.m

8686

Occupant Density (PTT Bld.)Occupant Density (PTT Bld.)

9393

Office Equipment Load FactorOffice Equipment Load Factor

9494

Actual Load FactorActual Load Factor

160160

Duct Heat Gain & Leak LossDuct Heat Gain & Leak Loss

Duct Heat Gain in % of RSHDuct Heat Gain in % of RSH --Supply Duct 1.5% (Typical Value)Supply Duct 1.5% (Typical Value) --Return Duct 1.5% (Typical Value)Return Duct 1.5% (Typical Value)

Duct Leakage in % of Total Air SupplyDuct Leakage in % of Total Air Supply --Supply Duct 3% (Typical Value)Supply Duct 3% (Typical Value) --Return Duct 0% (Typical Value)Return Duct 0% (Typical Value)

Note that these value are only approximated.Note that these value are only approximated.

161161

Effect of Internal MassEffect of Internal Mass

162162

Room Temperature VariationRoom Temperature Variation

107

Diversity Factor & Block Load

3333

Earth OrbitEarth Orbit

3434

DeclinationDeclination