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HVAC – Air Handling Unit

hQ = 200,000 Btu/h. HVAC – Basic Terms. cQ. assumeto = 20. tr = 70. CO2. 50 people. 20 cfm/pers. tsi = 105. 1000 cfm. 20%. coil Q = V*rho *cp*TD 5000 cfm. ti = 62. hQ vent = V*rho*cp*TD. Heating. Ventilating. AC =Cooling. HVAC – Air Handling Unit. HVAC – Basic Terms.

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HVAC – Air Handling Unit

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  1. hQ = 200,000 Btu/h HVAC – Basic Terms cQ assumeto = 20 tr = 70 CO2 50 people 20 cfm/pers tsi = 105 1000 cfm 20% coilQ= V*rho*cp*TD 5000 cfm ti = 62 hQvent = V*rho*cp*TD Heating Ventilating AC =Cooling HVAC – Air Handling Unit

  2. HVAC – Basic Terms (Heating Load)Heat Out = Heat In (Cooling Load including “Latent Load”) Heat and Humidity in = Heat and Humidity out By Conduction Convection Radiation

  3. HVAC – Basic Terms Conduction Area Temperature Resistance

  4. HVAC – Basic Terms Conduction

  5. HVAC – Basic Terms Convection Radiation

  6. HVAC – Basic Systems Heating hQsen = 200,000 Btu/h hQsen + hQvent = coilQsen

  7. HVAC – Basic Systems Heating

  8. HVAC – Basic Systems - AC w AC Water to Water w

  9. HVAC – Basic Systems - AC A w

  10. HVAC – Basic Systems - AC A A

  11. HVAC – Basic Systems - AC w A

  12. Constant Volume Double Duct Terminal Box Damper blades change air flow as the pressure at the inlet to the box increases or decreases and in response to room temperature

  13. Variable Volume Single Duct Terminal Box Velocity = Sub Master 55 – 60o P Sensor Thermostat = Master cfm Pressure Independent (between Max and Min), based on room thermostat. If temperature rises, damper opens for more cooling. Air Flow is unaffected by other boxes in the system.

  14. Inlet Guide Vanes

  15. Variable Speed Drives

  16. Variable Speed Drives

  17. Variable Speed Drives

  18. Variable Speed Drives

  19. HVAC - Cooling ideal COP – dimensionless! – EER – dimensions of Btu/h/W! kpH’ evQ

  20. HVAC - Cooling The energy efficiency rating (EER) of an air conditioner is its BTU/h rating over its Wattage. Example: window air conditioner Rating: 10,000-BTU/h Power Consumption: 1,200 watts EER = 10,000 BTU/h/1,200 watts = 8.3 Btu/Wh Normally a higher EER is accompanied by a higher price.

  21. HVAC - Cooling • Choice between two 10,000-BTU/h units • 1. EER of 8.3, consumes 1,200 watts • EER of 10, consumes 1000 watts. • Price difference is $100. • Usage: 4 months a year, 6 hours a day. • Electricity Cost: $0.10/kWh. • =========================================== • 4 mo. x 30 days/mo. x 6 hr/day = 720 hours • (720 h x .2 kW) x $0.10/kWh = $14.40 Savings • Since the EER 10 unit costs $100 more, • it will take about seven years for this more expensive unit • to break even

  22. Energy Analysis Example

  23. ECM: Heat Recovery

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