VFD s to Optimize System Savings Keith Kempski Control Techniques
View VFD as the tip of the iceberg Integration with the E2 provides optimal savings Typical supermarket applications are reviewed State utility rebates are compared Energy savings presented
Supermarket Energy End Use
VFD Supermarket Applications AHU s RTU s Condensers Compressors Pumps Exh. Fans Compressors Air Handling Condensers RTUs
AHU Control Basic HSK Fan motor savings 15 Diagnostic parameters Modbus communication to BMS
AHU High Value Integrated System HSK Fan Speed Control Broken Belt Detection Energy Meter E2 Space Temperature Economizer Heat/Cool Staging Compressor Staging Power Monitoring Air Handler
AHU High Value Integrated System HSK Air Handler Autotune easy set up Fan Speed Control Broken Belt Detection Local Alarm Remote Alarm Occurs within short time period Maintains Comfort Energy Meter kwh reading $/kwh input Running Cost E2 Communication Benchmarking of store performance
AHU High Value Integrated System HSK Optimization tips 1 or 2 Hz motor speed change can reduce energy by 14% Savings vary by location Use Energy Meter to trend energy Air Handler
AHU High Value Integrated System Air Handler Complete Space Temperature and Humidity Control Economizer 6 types Heat/Cool Staging Multiple stages Fan speed control Compressor Control Copeland Digital Scroll HSK variable speed Power Monitoring Reduce demand and cost HSK reduce motor speed and power
Air-Cooled Condenser Control HSK control Full modulation Temperature Differential Power Monitor Demand Control Same as AHU
Air-Cooled Condensers VFD control Full modulation Temperature Differential Power Monitor Demand Control
Air-Cooled Condensers VFD control Full modulation Pressure Transducer or Temperature Sensor Variable speed fan control all fans controlled Variable speed/constant speed first stage variable speed. Other stages start/stop
Air-Cooled Condensers VFD control continued Temperature Differential Pressure transducer or temperature sensor Ambient air vs. refrigerant temperature Control for specific refrigerant VFD control of first stage heat rejection Constant speed fans activated for additional cooling
Exhaust Fans Compressor rooms or warehouses Remove waste heat Room thermostat starts exhaust fan VFD varies fan motor speed to reduce energy use Optimum control Start fan at minimum speed Increase speed in increments A motor running at 30 Hz uses 12.5% of the energy as running at 60 Hz Simple retrofit
Secondary Systems Primary system (R-404A) Secondary System (Glycol)
Secondary Pumping Systems Low GWP Reduces amount of refrigerant in system up to 90% Reduces cost of refrigerant replacement Heat exchanger transfers heat from secondary to primary system Glycol is typical secondary refrigerant Advantage simple, easy to maintain
Secondary Pumping Systems Pumps circulate glycol mixture to display cases and coolers Case solenoid valves open/close changing system pressure Vary motor speed to maintain constant secondary loop pressure differential VFD s eliminate need to use balancing valves VFD s save energy and improves efficiency
CO2 Booster System Low GWP Reduces or eliminates refrigerant Successful in colder climates Booster System has been controlled successfully by Emerson E2 and HSK drives used in system
CO2 Booster System Medium Temperature Low Temperature
CO2 Booster System E2 Controller Synchronized MT and LT compressor control Gas Cooler fan control Communicates wit HP case controllers Remote monitoring and control of system HSK Drive MT compressor control 20 to 70 Hz modulation Energy savings proportional to speed (50% speed reduction = 50% energy savings Gas Cooler same control as aircooled condenser
Utility Energy Rebates (Incentives) Purpose of Rebate State Level Conserved energy is less costly than new power plants Rebates determined by avoided cost Type of Rebates $/HP (typically $30/HP to $100/HP plus) % installed cost of project (50% to 100%) Combination ($50/HP or 70% project cost) Rebate Amounts $30/HP to $1,000/HP (that get your attention?) Northeast highest rebates Other states vary and vary within states Texas and California offer rebates for demand (kw) reduction
Utility Rebates Available National Website to Find Energy Rebates State: New York Incentive Type: Utility Rebate Program Eligible Efficiency Technologies: Lighting, Chillers, Heat pumps, Central Air conditioners, Compressed air, Energy Mgmt. Systems/Building Controls, Motors, Motor VFDs, Comprehensive Measures/Whole Building, Custom/Others pending approval, Vending Machine Controls, Commercial Cooking Equipment Applicable Sectors: Commercial, Industrial, Nonprofit, Schools, Institutional Amount: Determined on a case-by-case basis Maximum Incentive: Prescriptive: $100,000 per project annually, $300,000 per customer annually Retrofit: $200,000 per building annually, $600,000 per customer annually Custom: $200,000 per building annually, $600,000 per customer annually Whole Building: $400,000 per building annually ($500,000 for LEED-certified), $800,000 per customer annually Commissioning Incentive: 75% of Commercial Efficiency Incentive, 50% of commissioning cost, $50,000 maximum Custom and Whole Building Additional Incentive: technical assistance up to $10,000; more complex projects can receive up to 50% of any additional costs.
Utility Energy Rebates (Incentives) Retail Solutions Makes it easy to find rebates State Utility Program Rebate Amount Web Link
Utility Energy Rebates (Incentives) Some states require preapproval or a site audit. Preapproval limited utility funding. Do early in the fiscal year Utility sets aside funds for your incentive Site audit usually done by utility rep Retail Solutions will help you by doing all the paperwork You choose Receive the rebate directly Have rebate sent to Retail Solutions (saves processing) For rebate sent to Retail Solutions Retail Solutions shows the rebate deducted from your bill Payment usually takes 6 to 8 weeks
Supermarket Customer Validates HVAC And Condenser Payback Savings Over Time kwh/month 12,000 10,000 8,000 6,000 68% Savings 4,000 2,000 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Store / Unit Before Annual kwh VFD Energy Savings Summary After Annual kwh Savings* Annual kwh Measured Percent Savings % of Total Store Total Store Savings Savings Annual VFD Cost Simple Payback Yrs Condenser 1561 Davis Cond B MT 120,196 83,709 36,488 30% 4.6% 1.4% $4,379 1502 Pleasanton Cond A LT 112,694 62,148 50,546 45% 3.6% 1.6% $6,066 Condenser Totals 87,034 38% 8.3% 3.1% $10,444 15000+ 1.5 AHU Main 1561 Davis AHU 125,268 33,966 91,302 73% 4.7% 3.4% $10,956 1502 Pleasanton AHU 125,268 45,535 79,733 64% 5.2% 3.3% $9,568 AHU Averages 85,517 68% 3.4% $10,262 5000+ 0.5 *Based on monitored kwh and outdoor temperature readings applied to annual Bin temperature hours.
Cold Storage 400hp Compressor Application 1 x 400hp ammonia compressor. Changed from soft starter (ON/OFF control) to VFD control. Reduced energy consumption by 14%. Payback period - 1 year 1 month Improved temperature control. Operating flexibility with varying loads. Less starting and stopping. 26
Grocery Store Exhaust Fans 4,500+ x 7.5 HP drives on exhaust fans. Changed from fixed speed to variable speed control. VSD total cost - approx $1,560,000. Energy savings - $832,000 per year Payback period - 1 year, 10 months. Increased equipment life and better diagnostics. Reduced maintenance cost, reduced noise & vibration. $832k on the bottom line every year after payback! 27
Where To Use VFDs Application Savings Complexity HVAC Supply and Return Air Fans Exhaust Fans Condensers Air-Cooled Evaporators Cooling Towers Compressors Refrigeration Heat Pump Pumps Secondary (Glycol) Heating and Cooling Cooling Tower Water Excellent Very Good Fair Good Easy Easy Difficult Mild
Getting Started Emerson Retail Solutions Survey Equipment Identify Physical Installation Constraints, Criteria Identify Existing BMS Interface Evaluate Power Quality For Filtering/Line Reactor Requirements Install Sub-metering To Establish Baseline Energy Consumption Engineer Controls Strategy Stages Of Heating/Cooling/Heat Reclaim BMS/Life Safety Integration Install Demonstration Site Validate Installation Procedures Provide On-Site Training For Service Provider Analyze Energy Consumption Post Installation Create Business Case For Enterprise Deployment
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