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Cooling

Summary From Last Week “ R” Values and “U” Factors “R” is Resistance to heat flow “U” is Conductance in Btuh / ft 2 / o F “ U” Factor Calculation “U” = 1 / (R 1 + R 2 + . . .+ R n ) Heat Transfer through surfaces “ Q”=”U” x Area x (T 1 –T 2 ). Cooling.

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Cooling

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  1. Summary From Last Week “R” Values and “U” Factors “R” is Resistance to heat flow “U” is Conductance in Btuh / ft2 / oF “U” Factor Calculation “U” = 1 / (R1 + R2+ . . .+Rn) Heat Transfer through surfaces “Q”=”U” x Area x (T1 –T2) Cooling Mechanical and HVAC Systems for Construction

  2. Summary From Last Week Heat Transfer to Air “Q” =“1.08”x CFM x (T1 –T2) For Air 1.08 = 0.24 Btu/Lb/oF x 60 Min/Hr x .075 Lb/Ft3 Cooling Mechanical and HVAC Systems for Construction

  3. Summary From Last Week Between 32 oF and 212 oF you get a 1 oF change in the Fahrenheit temperature of a pound of water for each Btu added. British Thermal Unit. Cooling 1 Kilowatt = 3412 BTU/Hr Btuh is commonly used for BTU/Hr Mechanical and HVAC Systems for Construction (not these guys)

  4. Summary From Last Week To change one pound of liquid water at 212 oF to one pound of steam at 212 oF you need to add 1000 British Thermal Units. The heat required for the change in state (or phase) from liquid to gas is the “Heat of Vaporization.” Cooling Mechanical and HVAC Systems for Construction

  5. Summary From Last Week To change one pound of liquid water at 212 oF to one pound of steam at 212 oF you need to add 1000 British Thermal Units. The heat required for the change in state (or phase) from liquid to gas is the “Heat of Vaporization.” Cooling Mechanical and HVAC Systems for Construction

  6. Transmission Heat Gain Calculation Element “R” Outside Surface 0.25 Lapped Siding 0.81 Sheathing 4.00 Batt Insulation 13.00 Wall Board 0.45 Inside Air Film 0.68 Total Resistance 19.19 “R” = ft2x °F x hr / Btu “U” = 1/”R” = 0.0521 Btuh / ft2 / oF Mechanical And HVAC Systems For Construction Cooling

  7. Mechanical And HVAC Systems For ConstructionCOOLING Heating

  8. Ventilation Heat Gain Calculation “Q” = 1.08 x CFM x Temp Diff say 100 CFM and 78oF inside and 96oF outside 100 x 1.08 x (95 -78) = 1836 Btuh for Sensible Cooling BUT, Wait! There’s More! Mechanical And HVAC Systems For Construction Cooling

  9. Here’s Where Cooling Load Calculations Start to Differ from Heating Load Calculations Adding Heat but no Moisture --- How Much Heat is needed? Cooling 25oF 72oF Mechanical and HVAC Systems for Construction

  10. Here’s Where Cooling Load Calculations Start to Differ from Heating Load Calculations =100 x 1.08 x (72 – 25) = 5076 Btuh Cooling 25oF 72oF Mechanical and HVAC Systems for Construction

  11. Dehumidification Load Calculations Cooling and Dehumidification from 95 Fdb /76FWb 78Fdb / 50%RH 95oFDB / 76OFwb Cooling 78oFDB/ 50% RH Mechanical and HVAC Systems for Construction

  12. Dehumidification Load Calculations Cooling Mechanical and HVAC Systems for Construction

  13. Dehumidification Load Calculations Cooling Mechanical and HVAC Systems for Construction

  14. Dehumidification Load Calculations 78oFDB 72.7% RH Cooling 95oFDB 76OFWB 78oFDB 50% RH Mechanical and HVAC Systems for Construction The air is cooler but the moisture content is still the same.

  15. Dehumidification Load Calculations Cooling 58oFDB 100% RH 95oFDB 76OFWB 78oFDB 50% RH Mechanical and HVAC Systems for Construction

  16. Dehumidification Load Calculations Cooling Mechanical and HVAC Systems for Construction

  17. Dehumidification Load Calculations Assume 100 Cfm Dry Wet RH DP Enthalpy BulbBulb Outside Air 95 76 42.4 68.5 39.3 Inside 78 64.9 50 57.9 29.9 Sat at OA 68.5 68.5 100 68.5 32.8 Sat at IA 57.9 57.9 100 57.9 25 1 -> 2 2892.5 Btuh = 4.45 x (39.3 - 32.8) x 100 2 -> 3 3471 Btuh = 4.45 x (32.8 - 25) x 100 3 -> 4 2180.5 Btuh = 4.45 x (29.9 - 25) x 100 Total 8544 Btuh Cooling Mechanical and HVAC Systems for Construction

  18. Dehumidification Load Calculations Dry Wet RH DP Enthalpy BulbBulb Heating 25 --- 100 25 8.92 72 50 15 25 20.26 1 -> 2 5046.3 Btuh = 4.45 x (20.26 - 8.92) x 100 Just to check 1 -> 2 5076 Btuh = 1.08 x (72 - 25) x 100 Cooling Mechanical and HVAC Systems for Construction

  19. Cooling Load Calculations Cooling Test Building 20’ x 15’ x 10’ 1 Glass Door 1 Steel Door Standing Seam Metal Roof One 3’x 5’ Window Each Side Mechanical and HVAC Systems for Construction

  20. Cooling Load Calculations Cooling Test Building 1 Concrete Block Wall 1 Block And Brick Wall 2 Frame Wall W/ Wood Studs Mechanical and HVAC Systems for Construction

  21. Cooling Load Calculations TEST BUILDING 4 Fluorescent Lights 2 People 2 Computer Sets Microwave Coffee Maker Small Fridge Cooling Mechanical and HVAC Systems for Construction

  22. Cooling Mechanical and HVAC Systems for Construction

  23. Cooling Load Calculations Cooling Mechanical and HVAC Systems for Construction

  24. Cooling Load Calculations Cooling Mechanical and HVAC Systems for Construction 8/1 7:30 AM 8/1 11:30 AM 8/1 4:30 PM

  25. SC Shading Coefficient SHGF Solar Heat Gain Factor CLF Cooling Load Factor CLTD Cooling Load Temperature Difference Cooling Mechanical and HVAC for Construction

  26. Cooling Mechanical and HVAC for Construction

  27. Cooling Mechanical and HVAC for Construction

  28. IBM Model 5150 September 1981 Price: US $1,565 ~ $3,000 CPU: Intel 8088, 4.77MHz RAM: 16K, 640K max Display: 80 X 24 text Storage: dual 160KB 5.25-inch disk drives OS: PC-DOS v1.0 Radio Shack TRS-80 (Model I) August 1977 Price: US $599.95 CPU: Zilog Z-80A, 1.77 MHz RAM: 4K, 16K max* Display: 12-inch monochrome monitor 64 x 16 text OS: BASIC in ROM* Cooling Mechanical and HVAC for Construction

  29. Cooling Mechanical and HVAC for Construction

  30. Cooling Mechanical and HVAC for Construction

  31. Cooling Mechanical and HVAC for Construction

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  33. Cooling Mechanical and HVAC for Construction

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