Phoenix Convention Center • Phoenix, Arizona

Challenges of Localized Cooling Systems

Integrated Energy District Heating and Cooling – Optimized Comfort

Brian BoydPacific Northwest National Laboratory

August 12, 2015

Energy Exchange: Federal Sustainability for the Next Decade2

This Presentation

Provides an example of challenges federal locations may experience if localized systems are implemented

Session IntentCompare the dynamics of localized versus district heating and cooling systems

with an emphasis on system performance for optimized occupant comfort

Introduction

Energy Exchange: Federal Sustainability for the Next Decade3

Background

• The site has 40 cooling towers and 42 water-cooled chillers

• Total water-cooled chiller capacity exceeds 3,000 tons

• Some systems operate seasonally, others operate year round

The Federal Energy Management Program (FEMP) sponsored a team from PNNL to provide O&M support in FY 2014 for a Naval facility in Japan having challenges with their evaporative cooling systems

Energy Exchange: Federal Sustainability for the Next Decade4

Cooling Towers – Two Different Designs

Induced-draft, counter-flow• Manufactured by Shinwa, Kuken, and

Mitsubishi• Range in size from 20 to 150 tons

Induced-draft, cross-flow• Manufactured by Shinwa and

Mitsubishi• Range in size from 100 to 150 tons

Energy Exchange: Federal Sustainability for the Next Decade5

Chiller Technologies

A variety of chiller

technologies are used

Daikin, Hitachi, and Toshiba units were

observed

Vintage and configuration varied

from building to building

Energy Exchange: Federal Sustainability for the Next Decade6

• Located on the ground, near the buildings they serve

• Evidence of algae on the fan blades and screens on top of the units

• Channeling and loss of flow through the tower fill

Counter-flow towers

Observed Challenges

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• Open distribution decks• Indications of compromised

water flow

Cross-flow towers

Observed Challenges

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Impact of Condenser Scale Deposits on Chiller Efficiency

Performance Implications

Condenser Deposit Thickness

(in.)

Equivalent Measurement

(mm)

Range of Efficiency Loss

(%)0.006 0.15 ~5

0.012 0.3 5-10

0.024 0.6 15-18

0.036 0.9 25-30

0.048 1.2 >35

Energy Exchange: Federal Sustainability for the Next Decade9

Uniform deposits are between 0.6 mm and 0.9 mm present throughout the condenser

Loss in efficiency is costing between $990 and $1,490 annually for this single chiller (based on $0.112/kWh electricity rate and calculated operating hours)

Cost Implications

Energy Exchange: Federal Sustainability for the Next Decade10

Discussion of localized versus district heating and cooling tends to

focus on the economic benefits of localized

systems

There may be upfront economic benefits, but

there are O&M challenges that can

increase lifecycle costs

This presentation highlighted observed

O&M challenges at one Naval facility and the

associated costs

Conclusions

Energy Exchange: Federal Sustainability for the Next Decade11

FEMP’s Water Efficiency Webpage:

energy.gov/eere/femp/water-use-reduction

For More Information…

Brian BoydResearch EngineerPacific Northwest National LaboratoryBrian.Boyd@pnnl.govOffice – (509) 371-6724