NEEA NBI RTU Projects ReviewRTUG Nov 8, 2012

• AirMax Indirect/Direct evap RTU-Idaho– 3 gen unit (2nd gen IDEC/Dx hybrid)– Add-on to existing 5 ton RTU

• Variable Rate RTU Test (VRTUT) 5-ton RTUs• NBI-L in Vancouver, WA + Fred Meyer-2 Idaho

locations

• Trane Precedent

• Daikin McQuay Rebel

• AAON RQ

•RTU physical model

Evaporative IDEC RTU Cooling Research Overview

• Project installation – Bigelow Tea facility in Boise Idaho: long term field site for NEEA

• Summer 2012 – good data for Aug/Sept• Savings projections: energy @ 50%(2,400

kWh/yr); demand @ 60% (3.6 kW) • Final report December • Potential to test next generation evap. unit

summer 2013

AirMax IDEC Product4th Gen Unit

• Blower change: from external rotor motor 960 W single-speed(2500@ 0.5 inch ) to 1.1 kW blower internal rotor 3-speed (3000 CFM @ 0.5 inch  or 2500 CFM @ 1 inch )

• Changed blower wheel from 450 mm with 130mm depth to 478mm with 170mm depth backward curve blower

• Control board changes:– Added LCD to replace dipswitches

– Runs the economizer or direct or direct /indirect as a 3-stages unit which saves water usage

– Increased purge system control accuracy

– TruPsych™ control board fully integrated into the cabinet

– Water coil and water pump redesigned completely to allow 100% winter drain down

– Standard’ beige cabinet color

IDEC Evaporative Project

Compressor Cooling Mode

Evaporative Cooling Mode

IDEC Evaporative Savings PotentialTo

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VRTUTTo

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Three high efficiency (code and better) units tested at NBI Lab, now in field measurement in Idaho 

The best performance was associated with the most efficient fan use

Short cycling losses not relevant if timed fan is used

ClimaCheck refrigeration diagnostics added

VRTUT-Typical Duty Cycle (Trane)To

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• Typical fan power ~ 400-600 W

• No short cycle loss if constant vent fan on

VRTUT-Rebel Duty CycleTo

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• Typical supply fan power ~130 W•  Most energy savings from low fan power

VRTUT- Comparison of 3 RTUsTo

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• Daikin McQuay Rebel performed about 30% better than base case (CAV-only) AAON RQa performed worse than base case when excessive supply fan power was used

• AAON RQb performed slightly better than base case when supply fan power was minimized

RTU Physical ModelTo

pic 1• NBI-L is closer to a ‘Field Site Lab’ with the capability

of simulating constant internal loading and measuring thermal output necessary to develop an RTU model

 • RTU model uses inputs derived from published unit

label data and unit site conditions • The conditioned space can be described by two

parameters: internal loading parameter (BTU/day) temperature dependency parameter

(BTU/deg day)

Physical Model Input ParametersTo

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• Nominal unit size, tons• Neutral temperature• COP at neutral temp• Airflow, lbs/minute• Fixed supply fan run, hours• Fixed supply fan power, W• Standby power, W• Fan Power during compressor, W• Economizer effect, 0 to 100%• Minimum OSA fraction, % full flow• Thermal effect at space, BTU/deg

day• Space gain, BTU/day

Physical Model - Data FitTo

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Physical ModelMain Energy Components

Top

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Projects StaffTo

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NBIMark Cherniack markc@newbuildings.orgHowdy Reichmuth howdy@gorge.netDan Harris dan@newbuildings.orgMark Lyles markl@newbuildings.orgAdam Sherba adam@newbuildngs.org

Idaho Design LabBrad Acker backer@uidaho.edu