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A Chilled Water System Analysis Tool for Industrial Assessments Chiller System Optimization & Energy A Chilled Water System Analysis Tool for Industrial Assessments Chiller System Optimization & Energy Efficiency Workshop September 2003 Presented by Michael Socks UMass Industrial Assessment Center

The Industrial Assessment Center at UMass-Amherst • The IAC performs no-cost, on-site energy efficiency, The Industrial Assessment Center at UMass-Amherst • The IAC performs no-cost, on-site energy efficiency, waste reduction, and productivity improvement assessments for small and mid-size manufacturers • Client Characteristics: 1) SIC Code 2000 -3999 2) Annual energy bills of $100, 000 to $2, 000 3) Gross annual sales less than $100 million 4) Fewer than 500 employees at the plant site 5) No in-house staff to complete a similar assessment

Summary of Operating Cost Reduction Measures Equipment-based Opportunities • Replace the chiller • Install Summary of Operating Cost Reduction Measures Equipment-based Opportunities • Replace the chiller • Install NG or absorption chillers (Hybrid) • Install HX to recover condenser heat • Store thermal energy for peak use

Summary of Operating Cost Reduction Measures Control-based Opportunities • Optimize chiller sequence • Raise Summary of Operating Cost Reduction Measures Control-based Opportunities • Optimize chiller sequence • Raise chilled water temperature setting • Lower condenser cooling water temperature • Use variable speed capacity control • Use 2 -speed or VSD control of tower fans • Use VSD control of pump flow • Use free cooling

Summary of Operating Cost Reduction Measures Load-based Opportunities • Use chilled water efficiently • Summary of Operating Cost Reduction Measures Load-based Opportunities • Use chilled water efficiently • Distribute chilled water efficiently • Use optimal coil or heat exchanger size/design

Program Introduction Purpose: Reduce the energy consumption of installed chilled water systems Goal: Create Program Introduction Purpose: Reduce the energy consumption of installed chilled water systems Goal: Create a simple but useful software tool for analyzing potential energy savings in chilled water systems

Chilled Water System (Water-Cooled) Chilled Water System (Water-Cooled)

Chilled Water System (Air-Cooled) Chilled Water System (Air-Cooled)

Program Description Visual Basic Executable Program • User is prompted for system information • Program Description Visual Basic Executable Program • User is prompted for system information • Program analyzes the existing system • User is prompted for changes to system • Program analyzes the proposed system • Program presents savings results

Program Overview: Input Basic System Data: • • Number of chillers (up to 5) Program Overview: Input Basic System Data: • • Number of chillers (up to 5) Chilled water supply temperature Geographic location Condenser cooling method (water or air)

Program Overview: Input If chiller condensers are water-cooled: • Condenser cooling water supply temperature Program Overview: Input If chiller condensers are water-cooled: • Condenser cooling water supply temperature (if constant) • WB to cooling water temperature differential (if variable) • Cooling Tower Data (# towers, # cells/tower, motor hp, # motor speeds)

Program Overview: Input If chiller condensers are air-cooled: • Cooling air design temperature • Program Overview: Input If chiller condensers are air-cooled: • Cooling air design temperature • Average annual ambient air temperature (if indoor air is used for cooling) • DB to condenser temperature differential (if outdoor air is used for cooling)

Program Overview: Input Pump Data: • • Fixed or variable flow pumping Flow rate Program Overview: Input Pump Data: • • Fixed or variable flow pumping Flow rate [gpm/ton] Nominal pump efficiency [%] Nominal motor efficiency [%]

Program Overview: Input Chiller Data: • • Chiller compressor type Chiller capacity Chiller full Program Overview: Input Chiller Data: • • Chiller compressor type Chiller capacity Chiller full load efficiency (if known) Chiller age

Program Overview: Input Energy Cost Data: • Average electricity cost [$/k. Wh] • Average Program Overview: Input Energy Cost Data: • Average electricity cost [$/k. Wh] • Average NG cost [$/MMBtu] System Control Data: • System operating schedule • System loading schedule

Program Overview: Cost Reduction Measures to Consider: • • • Increase chilled water supply Program Overview: Cost Reduction Measures to Consider: • • • Increase chilled water supply temperature Decrease chiller condenser temperature Upgrade to 2 -speed or variable speed tower fan motors Upgrade to variable speed pump motor control Replace chillers (use more efficient or NG units) Replace refrigerant Install VSD on chiller compressor motor (centrifugal only) Use free cooling Sequence chillers

Program Overview: Output Information: • Annual chiller energy consumption (k. Wh and/or MMBtu) and Program Overview: Output Information: • Annual chiller energy consumption (k. Wh and/or MMBtu) and cost • Annual cooling tower energy consumption (k. Wh) and cost • Annual pump energy consumption (k. Wh) and cost • Total annual energy consumption and cost

Program Overview: Output Chiller energy may be viewed by: • Chiller • Load Cooling Program Overview: Output Chiller energy may be viewed by: • Chiller • Load Cooling tower energy may be viewed by: • Wet-bulb temperature group Pump energy may be viewed by: • Chiller

Example Let’s run an example. . . • • • (3) 200 ton water-cooled Example Let’s run an example. . . • • • (3) 200 ton water-cooled chillers (centrifugal) 44 ºF chilled water temperature Located in Boston, Massachusetts Condenser cooling water is held constant at 85 ºF (1) 2 -cell tower with 15 hp 2 -speed motors Chilled water flow is constant [2. 4 gpm/ton] Condenser water flow is constant [3. 0 gpm/ton] Electricity is $0. 06 per k. Wh Operates 24/7 and serves an air-conditioning load Install VSDs on each chiller compressor motor

Example: Input Screen Example: Input Screen

Example: Output Screen Output Summary: • • Chillers: 2, 187, 676 k. Wh (92%) Example: Output Screen Output Summary: • • Chillers: 2, 187, 676 k. Wh (92%) Tower: 4, 768 k. Wh (< 1%) Pumps: 193, 934 k. Wh (8%) Total Energy: 2, 386, 378 k. Wh Total Cost: $143, 183

Example: Operating Cost Reduction Opportunities Screen Operating Cost Reduction Measure: • Install a VSD Example: Operating Cost Reduction Opportunities Screen Operating Cost Reduction Measure: • Install a VSD on each Centrifugal Compressor Motor

Example: Savings Screen Savings Summary: • 598, 797 k. Wh/yr • $35, 928/yr Example: Savings Screen Savings Summary: • 598, 797 k. Wh/yr • $35, 928/yr

Case Study: Application Manufacturer of laminated circuit boards uses chilled water for process cooling Case Study: Application Manufacturer of laminated circuit boards uses chilled water for process cooling and space conditioning Process Cooling • Laminating oven cool-down cycle • Plating fluid temperature control Space Conditioning • ~ 50, 000 ft 2 clean rooms • Office and manufacturing floor air conditioning

Case Study: System Specs Chilled Water System Summary • (2) 250 -ton helical rotary Case Study: System Specs Chilled Water System Summary • (2) 250 -ton helical rotary chillers (1997) • (2) 350 -ton helical rotary chillers (2001) • 45ºF chilled water; 2. 4 gpm/ton • 75ºF condenser water; 3. 0 gpm/ton • (4) cooling towers; (3) 15 -hp fans each (2 -speed) • Operates 24/7 year-round • Free cooling is used when possible

Case Study: System Loading Typical Loading Schedule • 20% load for 25% of year Case Study: System Loading Typical Loading Schedule • 20% load for 25% of year • 30% load for 25% of year • 40% load for 25% of year • 50% load for 25% of year Note: These are average system loads. Individual chiller loading will differ.

Case Study: Results Case Study: Results

Case Study: Prediction vs. Actual Without Using Free Cooling • 3, 478, 905 k. Case Study: Prediction vs. Actual Without Using Free Cooling • 3, 478, 905 k. Wh actual • 3, 436, 931 k. Wh predicted • Difference: 41, 974 k. Wh (-1. 2%) With Free Cooling • 489, 054 k. Wh and $41, 570 actual savings • 608, 720 k. Wh and $51, 744 predicted savings • Difference: 119, 666 k. Wh and $10, 174 (+24%)

Case Study: Other Observations • Chiller and pumping energy decrease by approximately 22% • Case Study: Other Observations • Chiller and pumping energy decrease by approximately 22% • Tower energy increases by approximately 63%

Closing Comments • The Program IS NOT intended to determine system energy use down Closing Comments • The Program IS NOT intended to determine system energy use down to the k. Wh or MMBtu • Program IS intended to direct analysis effort toward the most promising cost reduction opportunities • I need your help to make this program better: 1) Download the program from www. ceere. org 2) E-mail questions, suggestions, errors, etc. to me at [email protected] umass. edu • Any questions?