IPCX Chillers - Dunham-Bush Americas

DESIGN FEATURES: PART-LOAD PERFORMANCE○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○IPCX Rotary Screw Water Chillerspossess superior part-load performance characteristics.This is accomplished with the infinite capacity controlcapability of the slide valve equipped compressor.Actual process loads are significantly less than full loaddesign conditions, therefore chillers operate at full loadfor only a fraction of the operating time.IPCX Rotary Screw Water Chillerscombine the efficient operation of the rotary screwcompressor with finite refrigerant management andmicroprocessor control to yield the best total energyefficiency and significant operating savings under anyload.When specifying process cooling equipment it isimportant to consider the system load characteristicsof the process application. In a typical city, the airconditioning load will vary according to changes in theambient temperature. Weather data compiled overmany years will predict the number of hours thatequipment will operate at various load percentages.The Air Conditioning and Refrigeration Institute (ARI)has established a system, in ARI 550/590-98, formeasuring total chiller performance over full and partloadconditions. The Integrated Part-Load Value (IPLV)is an excellent method of comparing diverse types ofequipment on an equal basis. The IPLV is a singlenumber estimate of a chiller’s power use weighted forthe number of hours the unit might spend at eachpart-load point. IPLV’s are based on Standard ARI RatingConditions.For COP and EER:IPLVorNPLVFor kW/ton:= 0.01A+0.42B+0.45C+0.12D (1a)where: A = COP or EER at 100%B = COP or EER at 75%C = COP or EER at 50%D = COP or EER at 25%IPLVor =10.01 0.42 0.45 0.12+ + +A B C DNPLVwhere: A = kW/ton at 100%B = kW/ton at 75%C = kW/ton at 50%D = kW/ton at 25%(1b)Non-Standard Part-Load Values (NPLV) also give asingle number estimate for the part-load performanceof a chiller but at Selected Application RatingConditions.Integrated Part-Load Values and Application Part-LoadValues are available from your Dunham-BushRepresentative and will be calculated for your specificconditions. These points, as well as the full loadselection point, are all covered under the ARI LargeTonnage Certification Program for Centrifugal andRotary Screw Water-Chilling Packages.17