Field Trip Time: Tomorrow (Tuesday) 8 am Duration 1 hour (you will be back latest at 10 am) Location Texas State University: Round Rock Meet at the parking lot in front of the cooling tower You will see Cooling towers Chillers Water distribution AHUs (heat exchangers, humidifiers, ….) Duct and supply systems Control systems …..

Final Project Presentation Undergraduate students on Thursday in class Graduate student Friday morning ( doodle poll: ) Project and Presentation Prepare and me the ppt files 5-7 slides Introduce your problem (1-2 slides) –Problem –Why CFD? Methods (2 slides) –Description of the model –Tests, sensitivity analyses, … Preliminary results (2 – 3 slides) Report:

Objectives Finish with fans and compare them with pumps Learn about advance HVAC systems Review class material

VAV Operation

Fan Laws “Approximate relationships” Given two aerodynamically similar fans, can extrapolate performance data Be very careful

Pumps Driving force to move air water in buildings Raise pressure and produce flow One main type Centrifugal

Pump curves NPSHR = Net Positive Suction Head Required

Dampers

HVAC Control Example : Dew point control (Relative Humidity control) filter fan cooling coil heating coil filter mixing damper fresh air T & RH sensors We either measure Dew Point directly or T & RH sensors substitute dew point sensor Humidity generation Heat gains We should supply air with lower humidity ratio (w) and lower temperature

Relative humidity control by cooling coil T DP Mixture Cooling Coil Room Supply »Heating coil

Relative humidity control by cooling coil (CC) Cooling coil is controlled by T DP set-point if T DP measured > T DP set-point → send the signal to open more the CC valve if T DP measured < T DP set-point → send the signal to close more the CC valve cooling coil heating coil »mixing Fresh air T air & T DP sensors Control valves Heating coil is controlled by T air set-point if T air T air set-point → send the signal to close more the heating coil valve

Sensible, Enthalpy and Desiccant wheels

Desiccant wheel » Figure 3 – A desiccant-based cooling system combined with regenerative heat exchanger, vapor compression cooling, and evaporative humidifier (hybrid system).

Residential System

Commercial HVAC Systems Single zone Multi zone VAVCAV VAVCAV All Hydroinic that relay on infiltration With and without reheaters DOAS with fan coils or radiant ceilings With reheaters Dual duct Dual duct DOAS with fan coils With and without humidity control This is not the complete list !

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

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