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Letters to the Editor
Letters to the Editor CONTESTING ENERGY CLAIMS FOR NEWTON The best specific energy consumption (SEC) in kWh/m³*a (a stands for annum) achieved by NewTon NH 3 /CO 2 systems is approximately 35 kWh/m³ *a for a distribution center with a refrigerated volume of 4 4 , 0 0 0 m³(1,55 3, 8 4 5f t 3 ). This is according to the paper “Actual Energy Conservations by Using NH 3 / CO 2 Refrigeration System,” proceedings of the 3rd International Conference of Saving Energy in Refrigeration and Air Conditioning ICSERA 2013, H. Asano and N. Mugabi, both with Mayekawa, figure 7. According to ICR 2019 paper #466, “Real Energy Ef ficiency of DX NH 3 versus HFC,” authored by yours truly, figure 8, a DX NH3 two-stage system delivers a specific energy consumption of 20-24 kWh/m³*a when servicing a distribution center with a refrigerated volume of 44,000 m³. Also, in the paper “Comparing Energy Consumption and Life Cycle Costs of Industrial Size Refrigeration Systems,” authored by T. Lund, M. Skovrup and M. Holst of Danfoss, figure 1 shows that in all three jurisdictions investigated
LETTERS ARE WELCOMED! Accelerate Magazine invites readers to submit letters to the editor to michael.garry@shecco.com. Letters may be edited for clarity or length.
Accelerate Magazine // January 2020
(Rome, Frankfurt and Oslo) the R744/ R717 (CO 2 /NH 3) cascade system is less energy efficient than the equivalent dualstage R717 system with liquid overfeed. How then can the Accelerate Magazine article describing the recent NewTon i ns talla tio n c o m p l e te d by Tr i Te c h Refrigeration Australia in S ydney (“Australia Gets Its First Ammonia/ C O 2 N ewTo n S ys te ms ,” N ove m b e r December 2019) claim that the NH 3 / CO 2 system delivers significantly lower energy consumption than a conven tional liquid- overfeed system, unless the contractor or the user of the NewTon system produces the SEC in kWh/m³*a to substantiate that claim?” I have hereby provided the data to substantiate the claim that NH 3 /CO 2 cascade systems are generally less efficient than conventional dual-stage R717 systems, and significantly less efficient than the centralized low-charge NH 3 systems described in ICR 2019 paper #466.
Stefan Jensen Managing Director Scantec Refrigeration Technologies Brisbane, Australia