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

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

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

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

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

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

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

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

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)

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

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 Brian.Boyd@pnnl.gov Office – (509) 371-6724