What You Need to Know About Refrigeration Systems August 26, 2014 Source: NREL
Meet Your Panelists: Mike Carter Sr. Engineer, CEM Justin Kale Certified Energy Manager Consumers Energy Subject Matter Experts: Steve Schouten, Corporate Account Manager, Business Customer Care David MacDonald, Marketing Manager, Consumers Energy Business Solutions 2
Table of Contents Cooling Basics Refrigeration Systems Energy Savings Controls Heat Recovery Advanced Technologies Source: EPA 3
Poll Question Which of the following do you believe is the MAIN issue for your refrigeration systems? a) Food quality b) Reduced maintenance costs c) Energy consumption d) Sustainability/environmental/carbon footprint e) Personnel and customer safety 4
Basics How is cold produced? Start by asking the following question: Have you boiled water? Then you place on a stove. and you add HEAT.. Water reaches 212f and starts Boiling Evaporator Steam forms liquid turns to vapor temperature remains constant for liquid and vapor 212⁰F 60⁰F 100⁰F 80⁰F 60⁰F 212⁰F 212⁰F You take water in a vessel.. How cold is it from the faucet/tap? What is the pressure over the water this whole time? Atmospheric Source: Emerson Climate Technologies 5
Basics How is cold produced? Evaporator All liquid has now changed to vapor; temperature stays the same until last drop of water has evaporated Additional heating turns vapor hot; vapor temperature now starts increasing Superheat Condenser Condensing Vapor turns to liquid; heat is given back Water reaches 212 and liquid starts cooling off 212⁰F 300⁰F 250⁰F 212⁰F 212⁰F 212⁰F 100⁰F 80⁰F 60⁰F Source: Emerson Climate Technologies 6
Basics Mechanical vapor compression cycle Compressor raises the refrigerant boiling temperature Refrigerant absorbs heat (changes from liquid to vapor) in evaporator coil Compressor raises temperature and pressure (changes refrigerant vapor back to liquid) Mechanical energy taken in, heat given off 7
Refrigeration Systems A functioning refrigeration system Works exactly like the system we saw on the previous chart Source: Emerson Climate Technologies 8
Refrigeration Systems Supermarket Racks Reach In Frozen Carbonated Beverage Ice Machine Walk In Source: Emerson Climate Technologies 9
Refrigeration Systems Air as a cooling media Blast freezer Source: Karachi - paratha import Spiral belt freezer Source: Comron International BV 10
Refrigeration Systems Contact freezing Plate freezer Source: IndiaMART InterMESH Ltd. 11
Refrigeration Industry Market Drivers Source: Emerson Climate Technologies 12
Refrigeration Systems Traditional direct expansion Baseline -5% to -15% energy consumption 45% to 50% less refrigerant Source: Emerson Climate Technologies 13
Refrigeration Systems Increasingly complex systems +5% to +15% energy consumption 35% to 45% less refrigerant Reduced leakage Less copper piping -10% to 0% energy consumption 45% to 55% less refrigerant 14
Refrigeration Systems Transcritical CO 2 booster system From -10% to +20% energy consumption 45% to 60% less refrigerant Source: Emerson Climate Technologies 15
Refrigeration Systems Transcritical CO 2 (R744) compressor Benefits Non-toxic Non-flammable Non-ozone-depleting Very low global warming potential Lower refrigerant cost Challenges Higher pressure required 400 to 1,600 psi compared to 5 to 350 psi for standard refrigerants (R404A And R410A) Less efficient at high ambient temperatures (>50 F) 20% to 50% percent higher capital costs Over 600 users worldwide Applications primarily in northern climates Technology improvements pushing applications further south Source: Emerson Climate Technologies 16
Energy Savings DX System Sensitivity Annual Analysis - Boston 370K Low Temp/1M Med Temp Load 17 Source: Emerson Climate Technologies
Poll Question Which of the following advanced refrigeration systems have you installed at your facility? Check all that apply. a) Distributed DX systems b) Secondary systems c) Cascade CO2 systems d) Transcritical CO2 systems 18
Energy Savings Walk-in refrigerator maintenance Check and replace door gaskets Keep clean and pliable Sweep gasket alignment can be adjusted Replace every three years Use infrared to check for air infiltration Adjust top and center door hinges (when applicable) Lubricate hinges annually Clean evaporator and condenser coils Keep air paths clear Keep evaporator drain lines open Check refrigerant charge 19
Energy Savings EISA 2007 amended EPCA 1975 requirements Energy efficiency of walk-in coolers and freezers Manufactured on or after January 1, 2009 Less than 3,000 ft 2 Door products Automatic door closers Firmly close all walk-in doors Air infiltration protection for open doors Transparent reach-in doors and windows Double-pane glass with heat-reflective treated glass AND gas fill (coolers) Triple-pane glass with either heat-reflective treated glass OR gas fill (freezers or coolers) ECM fan motors (< 1 HP) Efficiency standards based on annual walk-in energy factor (AWEF) Source: Kason Industries 20
Energy Savings Polarized refrigerant oil additives (PROA) Supplier claims Up to 30% energy reduction More-effective lubrication Improved heat transfer Independent testing showed no significant difference The Appliance Laboratory Florida Solar Energy Center - University of Central Florida Oak Ridge National Laboratory National Institute of Standards and Technology Source: clker.com 21
Controls Floating head pressure controls Allow the compressor head pressure to vary with outdoor conditions (fall/winter) Condensing temperature allowed to fall from 90ºF to 95ºF down to 70ºF The compressor has to do less work at lower head pressures Reduces refrigerator compression ratios Improves system efficiency Helps extend the life of the compressor Often a standard feature on new systems Not usually used in conjunction with heat recovery Estimated 3% to 10% savings Source: David Wylie, P.E., ASW Engineering 22
Controls Thermal mass thermometers Supplier claims A reduction in compressor cycles 3 minutes on, 2 minutes off = 12 cycles per hour 8 minutes on, 7 minutes off = 4 cycles per hour 4 minute (10%) reduction per hour Heated defrosts are reduced or eliminated Extended equipment life Concerns Low-pressure control systems (deli/meat/fish cases) must be reconfigured to use this control method Air temperature swing is increased Source: Universal Master Products EndoCube 23
Controls Black box controllers Expands the window of acceptable temperature conditions Operates compressors when their suction pressures are highest (most efficient) ORNL and other third party test reports show savings Typically 8% to 10% energy savings Also reduces peak demand by 2% Source: Smartcool Systems Inc. 24
Controls Use hot gas defrost The evaporator becomes a condenser Latent heat generated from condensation of gas to liquid Increase defrost efficiency Minimize convective heat losses Shorten defrost duration Reduce number of defrosts per day Use dry air (-100ºF dew point) air purge to prevent coil icing, thus no defrost Use on-demand defrost Source: Professor Don J. Cleland, Massey University, NZ 25
Heat Recovery Superheat or heat of condensation heat recovery systems Series or parallel condensers Direct to water heater option Passes the refrigerant gas through a double-walled heat exchanger surrounding a water storage tank Heat is available only when the refrigeration system is in operation Grocery with 3 tons refrigeration (16 hr/day) and hot water at 80 gal/hr Potential water temperature rise of 40 F ROI is 60% for natural gas and 100% (1 yr payback) for electric water heaters Source: Sporlan Division of Parker Hannifin 26
Heat Recovery Therma-Stor and Mueller's Fre-Heater Passes the refrigerant gas through a double-walled heat exchanger surrounding the water storage tank to provide free hot water Source: Therma-Stor LLC 27
Heat Recovery KeepRite JUH Heat Reclaim Unit Heaters A three-way valve in the discharge line directs the refrigerant flow either to the outside condenser or to the heat reclaim unit 20 F to 50 F temperature rise Source: KeepRite Refrigeration 28
Heat Recovery 29
Heat Recovery Boiler cost savings estimate Energy saved = [110 gal/min x 60 min/hr x 90 F rise] x [8.34 lb/gal x 1Btu/lbF 0.80] = 6,100 kbtuh Boiler cost = [6,100 kbtuh x 5,840 hrs] x [1 therm/100kbtu x $0.90/therm] = $320,000 per year Heat pump cost estimate Heat pump cost = energy cost + demand charge = [228 kw x 5,840 hrs x $0.06/kWh] + [228 kw x $10/kW x 12 mth] = $80,000 + $27,000 = $107,000 per year 30
Heat Recovery Avoided boiler operating cost = $320,000 per year Heat pump operating cost = $107,000 per year Boiler savings of $210,000 per year, plus $83,000 Condenser annual water savings of 12 million gallons per year ($70,000) Reduced power draw on source refrigeration compressors (50-80 HP or $13,000) < 3-year payback Annual savings = $293,000 Estimated capital costs = $570,000 (equipment) + $200,000 (install) = $770,000 31
Advanced Technologies Source: Emerson Climate Technologies, Inc. 32
Advanced Technologies Microchannel Heat Exchanger (MCHX) technology Improved heat transfer and thermal performance Increased coil and overall unit efficiencies Substantial refrigerant charge reduction More compact and reduced coil size Estimated 5% energy savings Source: Johnson Controls 33
Advanced Technologies Electronic expansion valves (EEV/EXV) Expansion valves control evaporator superheat Held constant by thermostatic expansion valve (TXV) Controlled by springs, bellows, and push rods Handles low load down to 50% Variable (lower) superheat by EXVs Better control of discharge air temperature Handles low load down to 5% EXV uses stepper motors 200 steps per second Benefits Up to 15% energy savings Best in cooler climates Sensors enable system diagnostics Compatible with multiple refrigerants Source: Emerson Climate Technologies, Inc. 34
Poll Question How valuable has this Webinar been to you? a) Not valuable at all. The content was too technical and detailed for me to understand. b) Slightly valuable. It was worth attending, but I would not recommend it to anyone. c) Moderately valuable. Content was interesting and informative, but only increased my knowledge or comfort level with refrigeration systems a little. d) Very valuable. This was time well spent and I learned a lot. e) Extremely valuable. My knowledge of refrigeration systems has increased considerably. Would you like someone from Consumers Energy to follow up with you regarding today's webinar? 35
Advanced Technologies LED case lighting LED (20 watts) versus fluorescent (50 to 70 watts) Motion sensors reduce energy by another 25% The reduction on cooling load by LEDs represents about one-fourth of the total lighting energy savings 14 to 20 therms per year for a 5-door case Source: RPI Lighting Research Center 36
Advanced Technologies Vending machines NREL measurements Typical versus ENERGY STAR Capacity kwh/day Cost per Year ($0.09/kWh) ENERGY STAR 500 7.2 $236 $142 600 7.7 $253 $152 800 8.7 $286 $172 Technologies Occupancy sensors (VendingMiser ) Compressor Front-panel lights Replace fluorescent with LED Reduced air conditioning load in summer 37
Energy Efficiency Incentives Consumers Energy has rebates for refrigeration upgrades Energy Efficient Ice Machine LED Lighting and control for Refrigeration Cases Floating Head Pressure Control Evaporator Fan Demand Control and ECM motors Anti-Sweat Heater Controls Night Covers Reach-In Refrigerated Case Doors Strip Curtains Door Gaskets Custom industrial refrigeration projects may be eligible for an audit incentive 38
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