Workshop B Energy Efficiency Best Practices … Use of Smart Data Analytics for Commercial Building & Manufacturing Cooling Plants to Identify Opportunities Tuesday, February 18, 2020 10:45 a.m. to Noon
Biographical Information J. Kelly Kissock, Ph.D., P.E. Professor and Chair Dept. of Mechanical and Aerospace Engineering / Renewable and Clean Energy University of Dayton Kettering Laboratories 361-B, 300 College Park Dayton, OH 45469-0238 937-229-2835 Fax: 937-229-4766 kkissock@udayton.edu Dr. Kissock is a Professor and Chair of the Mechanical and Aerospace Engineering and Director of the Renewable and Clean Energy program at the University of Dayton. He is also Director of the University of Dayton Industrial Assessment Center. He is a Registered Professional Engineer in the State of Ohio. Dr. Kissock works in the fields of building, industrial and renewable energy systems. He has published over 100 technical papers on energy efficiency and renewable energy and conducted seminars on energy efficiency across the world. Dr. Kissock served as Associate Editor of the ASME Journal of Solar Energy Engineering and has chaired several technical committees and conferences. His work has been recognized with two Distinguished Educator Awards by Who’s Who Among America’s Teachers, the 2003 U.S. Department of Energy Center of Excellence Award, the 2006 Ohio Governor’s Award for Excellence in Energy, the 2009 University of Dayton Alumni Award for Scholarship and the 2011 Champion of Energy Efficiency award from the American Council for an Energy Efficient Economy.
Biographical Information J. Kelly Kissock, Ph.D., P.E. Professor and Chair Dept. of Mechanical and Aerospace Engineering / Renewable and Clean Energy University of Dayton Kettering Laboratories 361-B, 300 College Park Dayton, OH 45469-0238 937-229-2835 Fax: 937-229-4766 kkissock@udayton.edu Dr. Kissock is a Professor and Chair of the Mechanical and Aerospace Engineering and Director of the Renewable and Clean Energy program at the University of Dayton. He is also Director of the University of Dayton Industrial Assessment Center. He is a Registered Professional Engineer in the State of Ohio. Dr. Kissock works in the fields of building, industrial and renewable energy systems. He has published over 100 technical papers on energy efficiency and renewable energy and conducted seminars on energy efficiency across the world. Dr. Kissock served as Associate Editor of the ASME Journal of Solar Energy Engineering and has chaired several technical committees and conferences. His work has been recognized with two Distinguished Educator Awards by Who’s Who Among America’s Teachers, the 2003 U.S. Department of Energy Center of Excellence Award, the 2006 Ohio Governor’s Award for Excellence in Energy, the 2009 University of Dayton Alumni Award for Scholarship and the 2011 Champion of Energy Efficiency award from the American Council for an Energy Efficient Economy.
Smart Building Data Analytics for Cooling Plants Kelly Kissock Department of Mechanical and Aerospace Engineering / Renewable and Clean Energy University of Dayton, Dayton Ohio, U.S.A. jkissock1@udayton.edu 937-229-2852
Think Inside-Out Energy savings increase as move from “inside out”
Buildings: Upgrade Lighting and Windows Lighting: LED with occupancy and dimming controls Windows: Low SHCG or electrochromic that vary solar heat gain coefficient (SHGC)
Manufacturing: Reduce Heat Gain Into Cool Spaces “ about 3% of total cooling is to cool the product…. 97% is for removing heat from internal loads, infiltration and conduction”
Add HX Between Heating and Cooling Current: Qh1 = 100 Qc1 = 100 With HX: If Qhx = 30, Qh2 = 70 Qc2 = 30 HX reduces both heating and cooling loads!
Improve Air Handler Control Constant-Air-Volume to Variable-Air-Volume CAV reheat box Exhaust Air Return Air Fan Damper Qsen1 Qsen2 Interior Zone 1 Exterior Zone 2 Qlat1 Qlat2 Mixed Air Damper Tz1 Tz2 VAV Box VAV Box with Reheat Filter Supply Air Fan Cooling Coil Outside Air Damper Tsa Tma P 2 way valve 2-way valve VSD VAV box without reheat CW Supply CW Return HW Supply HW Return
CAV to VAV Cooling, Heating and Fan Savings Constant-Air-Volume mixes hot and cold to meet zone load Variable-Air-Volume varies air flow to meet zone load Cooling savings = 40% Heating savings = 40% Fan Savings = 50%
Improve VAV Fan Speed Control Fan Outlet Control Supply Duct Control Critical Zone Reset Control
VAV Fan Speed Control Strategies P B A B: Fan outlet C: Supply duct C D D: Critical zone reset V 2 = V 1 / 2 V 1 V
Reduce Static Pressure Setpoint Baseline: Post Baseline: Pset = 1.5” Dampers 65% Open Pset = 1.0” Dampers 67% Open Savings: 26%
Employ Robust Critical Zone Reset 51% fan energy savings
Improve Outdoor Air Control with Temperature-Based Economizer
Identify Economizer Problems Using Temperature Data Foa = (Tma – Tra) / (Toa – Tra) Functional Broken
Convert from Constant-Flow to Variable-Flow Pumping
Savings from Constant Flow to Variable-Flow Pumping A B Wsav = W 1 - W 1 (V 2 /V 1 ) 3 Wsav = (17 hp -7 hp) / 17 hp = 59%
Improve VSD Pumping Control A: P A B: B C D C: V 2 = V 1 / 2 V 1 V D:
Chiller Control
Increase Leaving Water Temperature at Low Loads kW/ton decreases as LWT increases Reset LWT with Toa Increasing leaving water temperature at low loads from (45 F and 0.92 kW/ton) to (60 F and 0.80 kW/ton) saves 13%
Chiller Efficiency Varies with Load Constant-speed: efficiency decreases as load decreases Variable-speed: efficiency increases as load decreases
Constant-Speed Chillers: Run Fewest Possible Running 1 chiller at (60% load and 0.30 kW/ton) instead of 2 chillers at (30% load and 0.37 kW/ton) saves 19%.
Variable-Speed Chillers: Run Maximum Possible Running 2 chillers at (40% load and 0.22 kW/ton) instead of 1 chiller at (80% load and 0.27 kW/ton) saves 19%.
Variable + Constant-Speed Chillers: Employ Controller So Variable is Always Trim Size VS at 125% of next biggest chiller to avoid control gaps. Saves 5-10%
Cooling Tower Control HOT HOT WATER WATER IN IN WARM AIR OUT Forced-air towers use Hot Water more fan energy then Distribution induced-air towers. Evaporation rate = 0.30% to 0.75%. AIR IN AIR IN Fill Fill Evaporated water qualifies for sewer Air Inlet Louvers exemption. Sump COLD WATER OUT
Select Energy-Efficient Cooling Towers Source: Variable Flow Over Cooling Towers, Marley Bigger towers cost more but reduce fan energy by 62%, saving $10,000 per year on $20,000 tower. Base Tower Efficient Tower Fan rated hp (RP) 40 15 Fraction loaded (FL) 0.8 0.8 Moter efficiency (Em) 0.9 0.9 kW/hp 0.75 0.75 Hours per year (HPY) 6,000 6,000 $/kWh 0.1 0.1 Energy Cost ($/yr) = RHP x FL / Em x kW/hp x HPY x $/kWh $ 16,000 $ 6,000 Annual Savings ($/yr) $ 10,000 Tower lifetime (years) 10 Total Savings $ 100,000
Install/Select VFDs on Cooling Tower Fans 10 F temperature drop and an 80 F set-point temperature Constant-speed fan is on 47% of year Variable speed runs at average of 37% of full speed. Overall, fan energy was reduced by 64%.
Set Cooling Tower to Min Condensing Water Temp kW/ton decreases as CWT decreases Decreasing cooling tower water set point from (70 F and 0.58 kW/ton) to (60 F and 0.50 kW/ton) saves 14%
Run Maximum Number of Cooling Towers CT capacity varies with fan speed 100% speed = 100% cooling capacity 75% speed = 75% cooling capacity 50% speed = 50% cooling capacity CT fan power varies with cube of fan speed ratio 100% speed = 100% 3 = 100% hp 75% speed = 75% 3 = 42% hp 50% speed = 50% 3 = 12% hp
Cooling Tower Control: Full Load: 3 Towers: Fan power = 60 hp 900 900 900 60 hp gpm gpm gpm 20hp 20hp 20hp 300 ton 10 hp 900 gpm 300 ton 10 hp 900 gpm 300 ton 10 hp 900 gpm
Cooling Tower Control: 2/3 Load: 2 Towers: Fan Power = 40 hp 900 900 0 40 hp gpm gpm gpm 20hp 20hp 0hp 300 ton 10 hp 900 gpm 300 ton 10 hp 900 gpm 0 ton 0 hp 0 gpm
Cooling Tower Control: 2/3 Load: 3 Towers: Fan power = 18 hp 600 600 600 FP 2 = FP 1 (V 2 /V 1 ) 3 18 hp gpm gpm gpm FP 2 = 20 (2/3) 3 = 6 hp 6hp 6hp 6hp 300 ton 10 hp 900 gpm 300 ton 10 hp 900 gpm 0 ton 0 hp 0 gpm At part load operate all cooling towers: 40-18 = 22 hp
Cooling Tower Control: 1/3 Load: 3 Towers: Flow less than 50% 300 300 300 3 hp! gpm gpm gpm 1hp 1hp 1hp 300 ton 10 hp 900 gpm 0 ton 0 hp 0 gpm 0 ton 0 hp 0 gpm Don’t run CTs at less than 50% water flow: Dry Tower Syndrome
Use Cooling Tower During Cool Months CoolSim calculates number hours CT delivers target temperature. Tc (F) Twb (F) Fyr (%) 75 65 72% 70 57 61% 65 50 53% 60 42 40% Fraction of year cooling tower can deliver water at Tc
Case Study
Eliminate Flow Through Inactive Chiller Chilled Water Leaving Temp 45 F chilled water from the active chiller combined with 55 F water from the inactive chiller to create 50 F supply water. Installing isolation valves: 1) enabled chilled water leaving temperature to be increased from 45 F to 50 F 2) decreased pumping energy Savings = 163,000 kWh/yr (16% reduction of total pump and chiller energy)
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