Heatload Calculation 2

HEAT LOAD CALCULATION 2

HEAT LOAD 2 1home back next

TOPICS COVEREDLOAD CALCULATIONS FORMS FORMULAS TABLES FACTORS AIR SIDE PSYCHROMETRY2home back next

HEAT LOAD 2

HEAT LOAD 2

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HEAT LOAD FORMSEE TRANSPARENCY


HEAT LOAD ESTIMATE PROBLEM

HEAT LOAD 2

General office Ceiling 10 Wall 4 brick, plastered both side Window- ordinary single glass internal shade Door- plywood sandwich air space Occupants - 35 person Lighting - Fluorescent 5home back next

DESIGN CONDITIONS

Outdoor design conditions 92F db / 80F wb or 95db/83wb Overestimating effect Night time temp. & rh different 76F db/ 75F wb / 95% rh


DESIGN CONDITIONS

Indoor design conditions Base on requirement and standards

75F db / 55% rh 72F db / 55% rh 71F db / 50% rh Peak time at 4.00 pm


CURRENT AIR-CONDITIONING DESIGN DATA COMPARISONJKR INDOOR TEMP.(o C) LIGHTING LOAD (w/ft2) OFFICE EQUIP. (w/ft2) OUTLET VELOCITY (ft/min.) FRESH AIR (cfm/person) 24 4-6 (2) 25-50* 20 ASHRAE 95 23-26 1.85-4.65 0.8-2 40-150 20 CIBSE 22+/-2 1.4 1.4 20

*-Carrier HandbookHEAT LOAD 2 8

QUESTIONFill in the table other information for the following conditions Outdoor air 92db/80wb Indoor 75db/55%rh


SOLAR GAIN THROUGH GLASS

Cooling Load = Window Area x Peak solar heat gain (Table 4) x Storage Factor (Table 5) x Shade Factor (Table 6) Refer to Table 4, Table 5 and Table 610home back next

HEAT LOAD 2

SOLAR AND TRANSMISSION GAIN

Heat Gain Through Walls & Roofs = Area x Equivalent Temp. Difference (Table 7 for wall & Table 8 for roof) x Transmission Coefficient (U) (Table 9)


TRANSMISSION GAIN (EXCEPT WALLS AND ROOFS)

Heat gain through all glass = Area x Temp. Difference (OA - RA) x Transmission coefficient (U) (Table 9) Heat gain through shade wall, partition = Area x Temp. Difference (OA - RA - 5F) x Transmission coefficient (U) (Table 9)


TRANSMISSION GAIN (EXCEPT WALLS AND ROOFS) (2)

Heat gain through wall, partition (adjacent to Kitchen,Boiler Room) = Area x Temp. Difference (OA - RA + 15F to 25F) x Transmission coefficient (U) (Table 9)


INFILTRATIONWhen ventilation exceeds infiltration (+ve pressure), then infiltration = 0 When rooms are design at -ve pressure, have to consider


INTERNAL LOADSPeople No. of people from no. of chairs or base on per floor area Table 10 - Heat gain from people

No. of people x Table 10 Activity, Sensible & Latent


INTERNAL LOADSPower Table 53 - Heat gain from electric motors Electric motors contribute only sensible heat to space


INTERNAL LOADSLights - Estimate (w/ft2) Lights - Type Incandescentrated lamp watt x 3.413

Fluorescent lamprated lamp watt x 1.25 x 3.413


INTERNAL LOADSAppliances most appliances contributes both sensible and latent heat load. They contribute latent heat by virtue of their function ex. drying, cooking Hood to remove this is most effective Table 50 & 51- Heat Gain from RestaurantHEAT LOAD 2 18home back next

SAFETY FACTORSafety factor added for possible error in the survey Over estimating safety factor will cause oversized air conditioning equipment - difficult to maintain space conditions < 5%19home back next

HEAT LOAD 2

ROOM SENSIBLE HEAT (RSH)Now all the load components contributing to sensible load can be added


SUPPLY AIR DUCT LOSSESIn transferring air from system cooling coil to space, four losses must be considered; HEAT LOAD 2 21home back next

Supply duct heat gain supply duct leakage loss fan heat bypassed outdoor air

SUPPLY DUCT HEAT GAINSupply air in the duct at 50F to 60F passes through surrounding environment above 90F - potential heat gain to supply air Insulation reduces this gain Typical figure < 2% of RSH


SUPPLY DUCT LEAKGE LOSSLost capacity in the supply air duct depends on duct shape, duct pressure and workmanship. Low pressure (0 - 2s.p) :

Heatload Calculation 2

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