1. Challenges of Localized Cooling Systems
Integrated Energy
District Heating and Cooling – Optimized Comfort
Challenges of Localized Cooling Systems
Brian Boyd
Pacific Northwest National Laboratory
August 12, 2015

2. Session Intent This Presentation Introduction
Compare the dynamics of localized versus district heating and cooling systems with an emphasis on system performance for optimized occupant comfort
This Presentation
Provides an example of challenges federal locations may experience if localized systems are implemented

3. 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

4. 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

5. Chiller Technologies A variety of chiller technologies are used
Daikin, Hitachi, and Toshiba units were observed
Vintage and configuration varied from building to building

6. Observed Challenges Counter-flow towers
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

7. Cross-flow towers Observed Challenges Open distribution decks
Indications of compromised water flow
Cross-flow towers

8. Performance Implications
Impact of Condenser Scale Deposits on Chiller Efficiency
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

9. Cost Implications
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)

10. Conclusions
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

11. FEMP’s Water Efficiency Webpage:
For More Information…
FEMP’s Water Efficiency Webpage:
energy.gov/eere/femp/water-use-reduction
Brian Boyd
Research Engineer
Pacific Northwest National Laboratory
Office – (509)