6/28/2016 OPTIMIZING CONDENSER PERFORMANCE Presented by: Rob Travis, P.E. 1 Thank you, sponsors Our online sponsors PLATINUM GOLD 1
6/28/2016 TOP 4 LOW COST CONDENSER ACTION ITEMS 1. Reduce Condensing Pressure 2. Enable Wet Bulb Approach 3. Proper Sequencing 4. Optimize Performance Courtesy: Evapco 3 1. REDUCE CONDENSING PRESSURE ‣ Rule of thumb savings: 1.5% compressor savings per degree‐F reduction in � condensing temperature ‣ Reducing minimum condensing pressure Action: Eliminating barriers to minimum allowable � pressure ‣ Reducing condenser approach Action: Increase condensing capacity � Important: Reducing approach and minimum pressure are completely separate issues, not to be confused or overlapped. 4 2
6/28/2016 MINIMUM CONDENSING PRESSURE ‣ Target of 90 (58°F) to 110 psig (68°F) psig for most systems (and in most climate zones) 100 90 80 70 Temperature (°F) 60 50 40 30 20 Wet Bulb, °F Minimum Condensing Baseline Condensing 10 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Shaded area represents decrease in energy by lowering the pressure setpoint to the minimum achievable value 5 ACHIEVABLE CONDENSING PRESSURE 6 3
6/28/2016 COMMON BARRIERS TO CONDENSING PRESSURE REDUCTION ‣ Hot gas defrost ‣ Heated zones Minimum ‣ Icing or other winter issues Pressure ‣ Water defrost and common sump Setpoint ‣ Oil separator performance ‣ Gas‐powered valves or unloaders Liquid Injection ‣ Liquid injection oil cooling Hot Gas Defrost ‣ Screw compressor oil carryover ‣ Underfloor heating DX Coils ‣ Pumper drum operation Oil Separator ‣ Direct‐expansion coils ‣ Process or door hot gas ‣ Inadequate liquid pressure to serve loads ‣ Concerns about condenser fan and pump energy ‣ Misperceptions about volume ratio and efficiency ‣ Tradition 7 2. ENABLE WET BULB APPROACH ‣ Wet bulb approach is a condensing strategy that strikes an effective balance between compressor power and condenser fan and pump power ‣ Ensures excess condenser power is not used to try to achieve an impossible condensing pressure based on a high wet bulb temperature Allows the condenser fans to “relax” without sacrificing � compressor power ‣ Approach value is based on condenser size and condition – typically 12°F – 18°F ‣ Incremental economic return with larger condensers. As approach decreases, additional condenser fan and pump power eats into compressor savings 8 4
6/28/2016 WHAT IS CONDENSER WET BULB APPROACH? ‣ Condenser approach is: Condensing Temperature ‐ Wet Bulb Approach 100 90 80 70 Temperature (°F) 60 50 40 30 20 Wet Bulb, °F 15°F Approach 25°F Approach 10 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Shaded area represents increase/decrease in energy between approach values 9 3. PROPER SEQUENCING ‣ (Excerpt from Evapco Catalog) Sequence condenser to operate: “pump‐fan‐pump‐fan” ‣ Pump‐only operation only provides 10% of Condenser Dry Operation Multiplier Condenser Dry Operation Multiplier total condenser 40% 40% capacity 35% 35% 30% 30% ‣ Capacity Multiplier Capacity Multiplier Fan only operation 25% 25% provides only 10% to 20% 20% Rating at Rating at 30% of rated capacity 90 psig 90 psig 15% 15% Condensing Condensing 10% 10% 5% 5% 0% 0% 35 35 30 30 25 25 20 20 15 15 10 10 5 5 0 0 Ambient Temperature (°F) Ambient Temperature (°F) 10 5
6/28/2016 MULTIPLE CONDENSER STAGING: MULTIPLE CONDENSER STAGING PUMP‐FAN‐PUMP‐FAN VS. PUMP‐PUMP‐FAN‐FAN Pump‐Fan‐Pump‐Fan vs. Pump‐Pump‐Fan‐Fan ‣ Keep the minimum number of condensers running where medium fan speeds are achieved ‣ Be mindful of water treatment concerns ‣ Avoid rapid pump cycling 11 4. OPTIMIZE PERFORMANCE Maintain condensers in optimal condition ‣ Good water distribution ‣ Clean pump strainers ‣ Clean out sump tank annually ‣ Check spray nozzles ‣ Inspect eliminators ‣ Stay on top of water treatment ‣ Tighten fan belts ‣ Ensure purger is functioning 12 6
6/28/2016 IMPACT OF SCALE ON CONDENSERS 13 CONCLUSION ‣ Reduce condensing pressure to the lowest limit allowable in the system ‣ Enable wet bulb approach condensing strategy. Set approach value between 12°F and 18°F ‣ Utilizing a Pump‐Fan‐Pump‐Fan strategy optimizes condenser power ‣ Maintaining condensers will result in compressor energy savings 14 7
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