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Course project presentation. Thursday in class Timing: 4 minutes (strictly controlled) Approximately 1 PowerPoint Slides per minute Content Problem Introduction Methodology Results Comments and recommendation You need to email me your presentation before the class!
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Course project presentation • Thursday in class • Timing: 4 minutes (strictly controlled) • Approximately 1 PowerPoint Slides per minute Content • Problem Introduction • Methodology • Results • Comments and recommendation • You need to email me your presentation before the class! • 2 minutes for Question and Answers
Final project report • Introduction • Methodology • Results • Comments • DO NOT submit pictures without comments • Analyze the result - create diagrams and tables
Objectives • Finish control systems – sequence of operation • Psychrometric chart • Learn about desiccant systems • Psychrometric chart • Learn about software for load calculation • Review
HVAC Control Example 2: Dew point control (Relative Humidity control) fresh air damper filter cooling coil heating coil filter fan mixing T & RH sensors Heat gains Humidity generation We should supply air with lower humidity ratio (w) and lower temperature We either measure Dew Point directly or T & RH sensors substitute dew point sensor
Relative humidity control by cooling coil Cooling Coil Mixture Room Supply • TDP • Heating coil
Relative humidity control by cooling coil (CC) • Cooling coil is controlled by TDP set-point if TDP measured > TDP set-point → send the signal to open more the CC valve if TDP measured < TDP set-point → send the signal to close more the CC valve • Heating coil is controlled by Tair set-point if Tair < Tair set-point → send the signal to open more the heating coil valve if Tair > Tair set-point → send the signal to close more the heating coil valve Control valves Fresh air • mixing cooling coil heating coil Tair & TDP sensors
Mixture 3 DPTSP Set Point (SP) Mixture 1 Mixture 2 • DBTSP Sequence of operation(ECJ research facility) • Control logic: • Mixture in zone 1: IF (( TM<TSP) & (DPTM<DPTSP) ) heating and humidifying • Heater control: IF (TSP>TSA) increase heating or IF (TSP<TSA) decrease heating • Humidifier: IF (DPTSP>DPTSA) increase humidifying or IF (DPTSP<DPTSA) decrease humid. • Mixture in zone 2: IF ((TM>TSP) & (DPTM<DPTSP) ) cooling and humidifying • Cool. coil cont.: IF (TSP<TSA) increase cooling or IF (TSP>TSA) decrease cooling • Humidifier: IF (DPTSP>DPTSA) increase humidifying or IF (DPTSP<DPTSA) decrease hum. • Mixture in zone 3: IF ((DPTM>DPTSP) ) cooling/dehumidifying and reheatin • Cool. coil cont.: IF (DPTSP>DPTSA) increase cooling or IF (DPTSP<DPTSA) decrease cooling • Heater control: IF (TSP>TSA) increase heating or IF (TSP<TSA) decrease heating
Figure 3 – A desiccant-based cooling system combined with regenerative heat exchanger, vapor compression cooling, and evaporative humidifier (hybrid system). Desiccant wheel
Computer software for load calculation • http://www.xpedio.carrier.com/idc/groups/public/documents/marketing/hap_ehelp_009.pdf • http://www.doe2.com/equest/ • http://tc47.ashraetcs.org/pdf/Presentations/Liesen_Chicago.pdf
Residential vs. Commercial systems • Course focus was on HVAC equipment that is used in both: residential and commercial systems • Emphasize on the application in commercial systems
Commercial HVAC Systems Multi zone Single zone All Hydroinic that relay on infiltration VAV CAV CAV VAV With and without humidity control With and without reheaters Dual duct Dual duct With reheaters DOAS with fan coils DOAS with fan coils or radiant ceilings This is not the complete list !
Typical Components in Commercial systems • Constant operation • Outdoor air supply • Two fans (supply and return) • Multizone system • Control • …..
Course objectives • Apply fundamental physical principles to HVAC design • Describe and size each component in an HVAC system • Design HVAC systems based on manufacturer’s datasheets • Contrast residential systems with commercial systems and use appropriate design techniques for each type of system • Solve HVAC design problems with high-quality references