HVAC Systems Overview HVAC Overview - # 1 Tom Lawrence University of Georgia HVAC Overview - # 1

Psychrometric questions? Email address list Agenda Psychrometric questions? Larger ‘psycho’ chart Email address list Project teams formed… topics? Overview of HVAC systems, types Tom Lawrence University of Georgia HVAC Overview - # 2

HVAC Systems Overview External Factors Ambient temperature, humidity Solar radiation Wind Equipment Internal Factors Occupants Moisture gains Acceptable environment (comfort, health and safety) Internal air distribution Tom Lawrence University of Georgia HVAC Overview - # 3

General Design Issues with HVAC Determine required indoor conditions Temperature and humidity levels Ventilation Determination of loads (cooling or heating) Heat transmission through building shell Heat gains from occupants Heat gains from lighting and equipment Ventilation and infiltration/exfiltration HVAC system type Building size, # of subdivisions Local energy prices Local climate Initial cost versus life cycle cost Other considerations Energy usage Indoor air quality Tom Lawrence University of Georgia HVAC Overview - # 4

Centralized versus decentralized Type of Systems All air Water / air All water Centralized versus decentralized Tom Lawrence University of Georgia HVAC Overview - # 5

Typical thermodynamic processes Cooling and dehumidifying moist air Evaporative cooling Humidity Ratio (W)   Dry Bulb Temperature Zone conditions,    Nearly saturated supply,   Ambient Tom Lawrence University of Georgia HVAC Overview - # 6

Typical processes (Cont’d) Heating     Ambient Ambient,  Zone conditions,  Mixed zone/ambient,  Heating to supply air, Tom Lawrence University of Georgia HVAC Overview - # 7

Direct Expansion Air Conditioning Outdoor Air COND Expansion Valve Compressor EVAP Supply Air Return Air Mixed Air Outdoor Air Tom Lawrence University of Georgia HVAC Overview - # 8

Central systems, Variable Air Volume (VAV) Common System Types Central systems, Variable Air Volume (VAV) Exhaust Air Return Fan VAV Supply Conditioning Coils Ventilation Air Supply Fan Tom Lawrence University of Georgia HVAC Overview - # 9

Central systems, Dual Duct Common System Types Central systems, Dual Duct Heating Coil (Hot Deck) Exhaust Air Return Fan Mixing Boxes Filters Ventilation Air Cooling Coil (Cold Deck) Supply Fan Tom Lawrence University of Georgia HVAC Overview - # 10

Fan Coil Units (Unit Ventilator) Common System Types Fan Coil Units (Unit Ventilator) Supply Air Supply Fan Cooling Coil Heating Coil Drain Pan Filters Ventilation Air Return Air Tom Lawrence University of Georgia HVAC Overview - # 11

Packaged Unit (Rooftop or Sidewall) Common System Types Packaged Unit (Rooftop or Sidewall) Direct Expansion Cooling Heat Pump or Gas Fired Heating Supply Air Return Air Alternate Supply and Return Ductwork Tom Lawrence University of Georgia HVAC Overview - # 12

Common System Types Split-System Return Air Condensing Unit Furnace Evaporator Refrigerant Lines Supply Air Tom Lawrence University of Georgia HVAC Overview - # 13

Chilled Water Systems Cooling Tower Chiller Chilled Water System  Various System Loads (Coils) Tom Lawrence University of Georgia HVAC Overview - # 14

Energy Recovery from Ventilation Air One common approach is enthalpy wheel Exhaust Intake Outdoor Air Exhaust Air Cooling Mode Supply Air Return Air Heating Mode Supply Air Return Air OA Exhaust Air Tom Lawrence University of Georgia HVAC Overview - # 15

Get ‘free cooling’ by using up to 100% outdoor air supply to room Economizer Systems Exhaust Air Return Air Recirculation Air Outdoor Air Supply Air @ Mixed Conditions Get ‘free cooling’ by using up to 100% outdoor air supply to room Controllers use enthalpy (T and H) or temperature only for control decision Tom Lawrence University of Georgia HVAC Overview - # 16

Cooling provided to building: Economizer Systems    Ambient Ambient,  Zone conditions,  Mixed zone/ambient,  Mixed air conditions: Cooling provided to building: Tom Lawrence University of Georgia HVAC Overview - # 17