2003 ASHRAE Annual Meeting Kansas City Energy Conservation Benefits of a DOAS with Parallel Sensible Cooling by Ceiling Radiant Panels Jae-Weon Jeong Stanley A. Mumma, Ph.D., P.E. William P. Bahnfleth, Ph.D., P.E. Department of Architectural Engineering The Pennsylvania State University (

2003 ASHRAE Annual Meeting Kansas City Presentation Outline Research background Pilot DOAS/CRCP system Energy simulation overview Energy conservation effects of the DOAS/CRCP system

2003 ASHRAE Annual Meeting Kansas City Problems of All-Air VAV Multiple spaces equation (ASHRAE Std. 62) Does not guarantee that individual space will always receive the intended OA quantity Conditioning and transporting air Consumes large quantities of energy Part load humidity problem Space humidity is passively controlled

2003 ASHRAE Annual Meeting Kansas City DOAS with Parallel Cooling

2003 ASHRAE Annual Meeting Kansas City Pilot DOAS/CRCP system Space Conditions 3200 ft 2 studio (43’ X 74’) 14’ ceiling height with 8 rows of pendent illumination at the 9-ft plane 40 students Office equipments (desk lamps, personal computers)

2003 ASHRAE Annual Meeting Kansas City Pilot System Configuration Two 5-ton Air Cooled Chillers Enthalpy Wheel 8 rows, 2’ X 13’ CRCPs 3-Way Valve (SA Temp Control) 3-Way Valve (Panel CHW Supply Temp Control) Cooling Coil High Induction Diffuser Variable Speed Drive (modulated EW speed)

2003 ASHRAE Annual Meeting Kansas City System Operating Stages Maintain Space DPT & DBT set-point If Space DBT > 75F (set-point) when SA = 52F (lower limit) Panel Pump is activated Tp = Space DPT + 3F

2003 ASHRAE Annual Meeting Kansas City EW and C/C controls A B C EA SA DPT (= 52˚F) h EA EW – Off C/C – Modulate (maintain SA condition) EW – Full Speed C/C – Modulate (maintain SA condition) EW – Speed Modulation (maintain SA DPT) C/C – Modulate or Off (maintain SA condition)

2003 ASHRAE Annual Meeting Kansas City Energy Simulation Simulated the pilot system and a VAV serving the same space For DOAS/CRCP pilot system simulation General purpose equation solving software General reciprocating air-cooled chiller model Quasi-steady CRCP model Curve-fit of Manufacturer’s EW performance data General Fan and Pump models were used

2003 ASHRAE Annual Meeting Kansas City Energy Simulation For conventional VAV system simulation Commercial energy analysis program was used For common base simulation Identical chiller part-load characteristic Identical hourly space sensible & latent loads Identical weather data (Williamsport, PA) were used

2003 ASHRAE Annual Meeting Kansas City Cooling Coil Load 57% of Peak C/C Load is shifted to the EW VAV DOAS/CRCP VAVDOAS/CRCP Operated for more hours 7.6 % of Annual C/C Load was reduced

2003 ASHRAE Annual Meeting Kansas City Chiller Energy Reduction Chiller Size VAV system: 14 ton DOAS/CRCP pilot system: 10 ton Annual Chiller Energy Consumption VAV system: 10.6 MWh/y (3.7 seasonal COP) DOAS/CRCP pilot system: 7.9 MWh/y (4.5 seasonal COP) 29% reduction 25% reduction

2003 ASHRAE Annual Meeting Kansas City Fan and Pumping Energy Fan Energy Reduction Design SA quantity: DOAS – 1200 scfm VAV – 3220 scfm Annual Fan energy: DOAS – 2.33 MWh/y VAV – 7.97 MWh/y Pumping Energy DOAS/CRCP system consumes as much pumping energy Counterbalanced by the greatly reduced fan and chiller energy 37% of VAV 71% Reduced nearly twice

2003 ASHRAE Annual Meeting Kansas City Total Energy Consumption DOAS/CRCPVAV Chiller Pump Fan 42% Reduced ! 19 MWh 11 MWh

2003 ASHRAE Annual Meeting Kansas City Conclusions Significant energy saving potential – over 40% Small SA quantity  Fan energy reduction Total energy recovery  Equipment size reduction Increased pumping energy Offset by reduced fan & chiller energy consumption Real operation data of the pilot DOAS/CRCP system pending ASHRAE & DOE funding More information –

2003 ASHRAE Annual Meeting Kansas City Questions?