Cooling Load-Lights,Occ,Equip

pdf

School

Concordia University *

*We aren’t endorsed by this school

Course

MISC

Subject

Mechanical Engineering

Date

Oct 30, 2023

Type

pdf

Pages

Uploaded by BarristerBoarMaster912

Cooling Load Calculation - CLTD Method (Internal Loads) ? ?,𝑧??? 𝑡 = ෍ 1 𝑁 q 𝑤 (𝑡) + ? ??? 𝑡 + ? 𝑖?? 𝑡 ?𝑖?ℎ??,??????,???𝑖????? +? 𝑖?? 𝑡

Sensible Cooling Load Due to Heat Gains from Lights, Occupants, and Equipment 1. Lights : ሶ? ?,?𝑖?ℎ?? 𝑡 = 3.41 ∙ 𝑊 ∙ 𝐹 ? ∙ 𝐹 ? ?𝐿𝐹 𝑡 ?𝐻 2. Occupants : ሶ? ?,????????? 𝑡 = 𝑁 ∙ ? ?,???????𝑖? ???? ∙ ?𝐿𝐹 𝑡 ?𝐻 3. Equipment : ሶ? ?,???𝑖????? 𝑡 = 3.41 ∙ 𝑊 ∙ 𝐹 ? ?𝐿𝐹 𝑡 ?𝐻 Fall 2023 BLDG 471 Dr. M. Zaheeruddin 2 cooling load factor, Table 8-27 ballast factor (usually 1.2) usage factor to convert watts to BH watts (installed lights wattage) Table 8-26 rate of sensible heat released by occupants, Table 8-11 Number of occupants Table 8-26 unhooded equip. Table 8-28 hooded equip. Watts, installed usage factor

Fall 2023 BLDG 471 Dr. M. Zaheeruddin 3

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

Fall 2023 BLDG 471 Dr. M. Zaheeruddin 4

Fall 2023 BLDG 471 Dr. M. Zaheeruddin 5

Question: Cooling Load due to heat gains from lights Office space • Has 8400 W of installed lights • Fluorescent 40 W lamp fixtures are used • Supply air from ceiling, air returning through ceiling plenum • Lights turned on at 8am and off at 6pm • Assume zone type B • Assume 15% of lights are off at any time • Take ballast factor = 1.2 for the fluorescent lamps Calculate the cooling load at 4pm. Fall 2023 BLDG 471 Dr. M. Zaheeruddin 6

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

Solution: Lights : ሶ𝒒 𝒄,𝒍????? ? = ?. ?𝟏 ∙ 𝑾 ∙ 𝑭 ? ∙ 𝑭 ? ?𝑳𝑭 ? ?𝑯 Fall 2023 BLDG 471 Dr. M. Zaheeruddin 7 ሶ? ?,?𝑖?ℎ?? 4?? = 3.41 ∗ 8400 ∗ 0.85 ∗ 1.2 ∗ ?𝐿𝐹 𝑡 = 29216.88 ∗ ?𝐿𝐹 𝑡 ?𝐻 15% of lights are off From table 8-27, Lights on from 8am-6pm = 10 hours Cooling load at 4pm means 8 hours after the lights were turned on. For Zone type B → 10 hours ON; 8 hours after: ?𝐿𝐹 16 = 0.96 (𝑇???𝑒 8 − 27) 10 hours ON; 8 hours after ∴ ሶ? ?,?𝑖?ℎ?? 4?? = 29216.88 ∗ 0.96 = 28048 ?𝐻

Question continued… Include heat gains due to occupants in office space :  Number of occupants = 10;  Working hours: 9am - 5pm;  Assume Zone Type B  Calculate the cooling load at 4pm. Solution: From Table 8-26 Read CLF CLF (8h stay, 7h after entry) = 0.93 Fall 2023 BLDG 471 Dr. M. Zaheeruddin 8

Solution: Fall 2023 BLDG 471 Dr. M. Zaheeruddin 9 For office work, from Table 8-11: ? ? = 245 ?𝐻; ? ? = 155 ?𝐻 ሶ? ?,?????????,????𝑖??? 16 = 𝑁 ∗ ? ? ∗ ?𝐿𝐹 16 = 10 ∗ 245 ∗ 0.93 = 2278.5 ?𝐻 8 hours stay, 7 hours after entry Table 8-26 ሶ? ?,?????????,?????? 16 = 𝑁 ∗ ? ? ∗ ?𝐿𝐹 16 = 10 ∗ 155 ∗ 1 = 1550 ?𝐻 Cooling load at 4pm: ሶ? ? 16 = ሶ? ?,????????? + ሶ? ?,?𝑖?ℎ?? = 2278.5 + 1550 + 28048 = 31877 ?𝐻

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

Guidelines (for the use of CLF factors): 1. CLF values given in Table 8-26 are for continuously operating HVAC systems. 2. If the cooling system operates in an ON-OFF control mode, CLF=1.0. 3. In the case of lights cooled by return air (vented fixtures), the cooling load on the space is reduced by 30-40%. Fall 2023 BLDG 471 Dr. M. Zaheeruddin 10