Low Charge ADX Ammonia Presented by: Bruce Nelson, President, Colmac Coil Manufacturing Rick Watters, Vice President, AMS Mechanical Systems
Background Why use ammonia? It s a natural refrigerant ODP = zero, GWP < 1 Abundant and low cost Widely used for over 100 years It is energy efficient! Table 8 Comparative Refrigerant Performance (Te = -25F, Tc = 86F) Refrigerant R744 Net Refrigerating Effect, Btu/lb 56.8 Refrigerant Circulated, lb/min 3.52 Power Consumption, Hp 2.779 Coefficient of Performance 1.698 R507A 43.5 4.60 1.833 2.573 R404A 45.1 4.44 1.817 2.595 R22 66.8 3.00 1.589 2.967 R717 463.9 0.43 1.569 3.007
Background Concerns with ammonia: Toxicity Flammability Regulations (> 10,000 lbs) OSHA Process Safety Management (PSM) EPA Risk Management Program (RMP) DHS Chemical Facility Anti-Terrorism Standards (CFATS)
Background Regulation and risk has driven interest in new low charge ammonia technologies Advanced Direct Expansion (ADX) is one method of reducing ammonia charge
Low Charge ADX Ammonia Benefits: Much smaller ammonia charge 7 lbs/tr vs 30+ lbs/tr for pumped bottom feed 30X to 50X charge reduction in evaporators Ammonia charge <10,000 lbs even for large systems Energy Efficient Lower first cost compared to pumped ammonia
Making ADX Ammonia work Three critical issues must be addressed: 1. Separated flow in evaporator tubes - Tube ID enhancement 2. Management/removal of water - Only dry high pressure liquid is used - Trap and remove water at the accumulator 3. Refrigerant distribution - Tank Distributor technology
Low Charge ADX Ammonia Many systems now in operation USA, Canada, Australia Large cold storage distribution centers Food service distribution centers Food processing facilities
Low Charge ADX Case Studies Rick Watters, AMS Mechanical Systems Vice President of Refrigeration/Food Process Piping
WHY USE ADX AMMONIA? Lower refrigerant operating charge Simplify Operation Location Location Location
JCS aerial view
JCS plan view with Phase 2-10 F/ +40 F CONVERTIBLE ROOM -10 F/ +40 F CONVERTIBLE ROOM -10 F FREEZER -10 F/ +40 F CONVERTIBLE ROOM -10 F FREEZER -10 F/ +40 F CONVERTIBLE ROOM -10 F FREEZER +40 F DOCK +40 F DOCK OFFICE SUPPORT MECH ROOM
LCS aerial view
+40 F COOLER LCS plan view with Phase 2 PRODUCTION +40 F COOLER -10 F/ +40 F CONVERTIBLE ROOM -10 F FREEZER -10 F FREEZER +40 F COOLER +40 F DOCK +40 F DOCK OFFICE SUPPORT MECH ROOM +40 F PRODUCTION MECH ROOM SUPPORT
JCS Refrigeration System Highlights Single stage economized -15/+20/+95 Thermosyphon oil cooling Anhydrator System Cleaner H.A. Phillips transfer system Controlled pressure receiver +20 and -15 accumulators Nickel-Brazed Liquid Sub-Cooler Motorized TXV s
Liberty Cold Refrigeration System Highlights Single stage economized -15/+20/+95 Thermosyphon oil cooling H.A. Phillips transfer systems Controlled pressure receiver +20 and -15 accumulators Nickel-Brazed Liquid Sub-Cooler Pulse Width TXV s
Refrigeration System Highlights VFD s on large evaporator fans
Refrigeration System Highlights VFD s on large evaporator fans ADX Evaporators
Refrigeration System Highlights VFD s on large evaporator fans ADX Evaporators Low Charge Condenser
Refrigeration System Highlights VFD s on large evaporator fans ADX Evaporators Low Charge Condenser Low Charge Vessels
JCS vessels
LCS vessels
JCS engine room
LCS engine room
Operating Efficiency Calculated 1.3% more Hp per ton compared to Liquid Overfeed Systems as worst case
Refrigerant Charge Comparison JCS with Phase 2 Liberty Comparison Freezer Temp. Deg. F -10-10 -10 Freezer sq. ft. 300,400 147,600 90,301 Convertible room. Deg. F -10/35-10/28-10/35 Convertible room sq. ft. 37,800 15,700 45,311 Dock Temp. Deg. F 40 40 40 Dock/Cooler area sq. ft. 63,600 88,500 35,958 Central Refrigeration System ADX ADX Pumped Liquid Refrigeration tons 1,060 647 335 Ammonia charge lb. 8,500 7500 24,000 Total refrigerated sq. ft. 401,840 251,800 171,610 Charge per square foot.0212 #/sqft.0298 #/sqft 0. 138#/sqft Charge per Ton of Refrigeration 8.02#/TR 11.59 #/TR 71.64 #/TR
Electrical Comparison Comparison JCS Phase 1 only Liberty Phase 1 only Refrigerated space sq. ft. 137,448 ft² 201,805 ft² 135,807 ft² Central Refrigeration Control System No Yes Yes VFD s on Large Evaporator Fan Motors No VFD s VFD s VFD s Motion Sensing LED Lighting No Yes Yes Blast Freezing No Yes Yes 2015 Total Power Usage (KWH) 5,165,708 KWH 4,721,655 KWH 4,227,007 KWH Annual Average Power per sq. ft. 37.6 KWH/ ft² 23.4 KWH/ ft² 31.1 KWH/ ft² Percent Difference (%) 0% 38% 18%
Construction Cost 2.37% savings over a liquid over feed $100,000.00
Design Considerations Use the recommended oil (Frick #9 in this case) Keep the system dry and oil free You will have some liquid return. Defrost, under floor system. Be able to deal with it Going to a fluid cooler for compressor oil cooling in place of thermosyphon would have reduced the ammonia charge 750#
Design Considerations (cont.) Fluid cooler system would have added $300,000.00 of install cost to the project Liquid injection would lower the install cost and refrigerant charge but would have decreased operating efficiency's by and additional 4.5% Law of unintended consequences
In Summary ADX Evaporators worked as advertised System is easy to work on Restarts quickly after power failure Both Motorized and Pulse Width DX valves work great Add Hot Gas heat cycle to evaporators in Coolers/Dock depending on location 5 projects completed, 1 under construction
Questions?