Achieving Dry Outside Air in an Energy-Efficient Manner PSU Building Thermal and Mechanical Systems Laboratory Environment A/E Stanley A. Mumma, Ph.D., P.E., Professor, and Kurt M. Shank, M.S. Graduate Department of Architectural Engineering College of Engineering Penn State University Park, PA

Presentation Outline l Introduction and Objectives l Potential Dedicated OA System Configurations l Psychrometric Analysis of the DOAS l Load and Hourly Energy Analysis of the Configurations l Conclusions and Recommendations

Objective l Develop a fundamental understanding of OA preconditioning equipment for dedicated OA systems composed of: Passive desiccant wheels, Sensible heat exchangers, Deep dehumidification cooling coils. l Present the design load and energy performance perspective.

Potential Configurations l #1, Conventional Cooling Coil, Heating Coil, and Humidifier; HC CC Humidifier OA

l #2, A Run around heat recovery system added to configuration #1. HC CC OA Humidifier

l #3, Passive Desiccant (Enthalpy) wheel added to the heating and cooling coils HCCC OA RA EW

l #4, Enthalpy wheel, Cooling Coil and run around Heat Recovery HC CC OA EW RA

l #5, Dual Wheel DOAS Unit CC OA EW RA SW F DBT, 45F DPT 80F DBT, 55F DPT 45F PH State Point #, typ

l #6, Conventional All Air VAV System with air side Economizer. –Illustration unnecessary

Design energy demand to treat 10,000 scfm of OA in Atlanta Conf. # CC load Tons Humid- ification k-Btu/hr Heating k-Btu/hr

Energy consumed to treat 10,000 scfm of OA in Atlanta (3744 hr) Conf. # CC TH Reheat k-Btu Heating k-Btu Humid ification k-Btu 1113,000255,000110,000155, ,00014,800110,000155, ,000255,0007, ,00014,8007, , , ,000

Four Regions on the Psych. Chart, w/ Atlanta Data Region A, 1,635 hours Region B, 784 hours Region C, 1,111 hours Wet regions Dry regions Region D, 214 hrs

l #5, Dual Wheel DOAS Unit CC OA EW RA SW F DBT, 45F DPT 80F DBT, 55F DPT 45F PH State Point #, typ

Region A, enthalpy wheel, cooling coil, and sen. wheel F Key: 1-2-6, enthalpy wheel 2-3, cooling coil 5-6, 3-4, sen. wheel

Region B, cooling coil, and sen. wheel F 1, Key: 1/2-3, cooling coil 5-6, 3-4, sen. wheel

Region C, enthalpy wheel and cooling coil F 1 2 5, 6 3, 4 Key: 1-2-5/6, enthalpy wheel 2-3/4, cooling coil

Region D, enthalpy wheel, and sen. wheel F Key: 1-2-6, enthalpy wheel 5-6, 3-4, sen. wheel

Control Status of DOAS Equipment (See Tech Paper 4428) RegionEnthalpy Wheel, CTL CC, CTLSensible Wheel, CTL A Max speed and effectiveness Modulate to hold 45F Modulate to hold 55F BOff Modulate to hold 45F Modulate to hold 55F C Mod. Speed to req’d DPT Modulate to hold 55F Off D Mod. Speed to req’d DPT Off Modulate to hold 55F

Conclusions: l The DOAS, configuration 5, exhibits superior demand and energy performance when compared to the other configurations analyzed. l The DOAS assures verifiable ventilation delivery. l Decoupled sensible and latent cooling contributes to improved comfort, health and productivity

Recommendation: l Make the transition to dedicated OA designs. l Use configuration 5 to decouple the space sensible and latent loads. l Save energy, improve quality of the spaces, and minimize litigation potential.