Ultralow-Charge Ammonia Refrigeration in Food Retail: A Successful Case Study

摘要

The refrigeration segment particularly for food retail segment has been moving towards adoption of alternative systems that use low Global Warming Potential(GWPJ and Ozone Depletion Potential CODPJ refrigerants.One of the key requirements is to do with little to no impact to their bottom line or disruption of operations.For such retail operators and supermarket owners,NH/C02 cascade system is one of the options to be future proof in terms of regulations on refrigerant use and achieving energy savings at the same time.This paper will describe in details all the aspects of designing,installing,commissioning and certification of energy savings for a medium size supermarket in southeastern USA.The subject of the case study comprises of a cascade refrigeration system with the low side using C02 as a refrigerant and with duplicate top sides.The duplicate top sides,one with ammonia and another one using HFC 407A refrigerant allows for same store comparison of energy consumption and reliability of the systems.The low side of the system is common between the duplicate top sides.The system is fully instrumented to allow for energy comparison and optimization studies on operating parameters and set points.The study shows an average 22% energy savings when operating with the ammonia top side vs.R407A.Another aspect of the paper is to outline design approach to minimize the charge to only 53/bs of ammonia for a total of 70TR of refrigeration capacity.The paper also delineates an oil system design and the safety precautions utilized to mitigate risks to the end user regarding reliability and ammonia releases.