INTERNATIONAL NEWS
INCORPORATING COLD CHAIN operation, the choice of the lubricant can vary depending on the type of compressor, the design of the system and, mostly, the kind of refrigerant.
Joseph A Karnaz presented his paper‘ Evaluating Lubricants for Lower GWP Refrigerant Compressor Operation’ at the 16th International Refrigeration and Air Conditioning Conference in Purdue. This paper evaluates five potential candidates as substitutes for R404A and the potential impact of lubricant chemistry. The refrigerants considered are three non-flammable HFO / HFCs( R448A, R449A, R452A), one slightly flammable HFO / HFC / CO 2 blend candidate( R455A), and one flammable HC candidate( R290). Investigation is made on how these refrigerants interact with lubricants( miscibility, solubility, system performance) and if current marketed lubricants used with R-404A are still good candidates to use with these lower GWP candidates.
Polyolester( POE) lubricant currently used with R404A in compressor operation is found to be satisfactory for use with most of the refrigerants investigated and has no negative effect on performance. By using ISO 22 POE lubricant, the effectiveness of R290 when compared to R404A shows better efficiency(+ 11 %) but some capacity loss(-10%), which could mainly be from thermodynamics, but
R290 high solubility levels could be playing a role.
Lubricants like mineral oils, which typically have been unacceptable for use with R-404A due to miscibility concerns, are also not miscible with the HFO / HFC refrigerants studied.
INVESTIGATION OF REFRIGERANT LEAKAGE IN COMMERCIAL REFRIGERATION An article from Christina Francis et al. presents the results of a project that investigated refrigerant leakage within two of the UK’ s major supermarket chains. The authors remind that the growth in the commercial refrigeration subsector is of concern, since it is reported to have the highest CO 2 equivalent emissions for the whole refrigeration, AC, and heat pump( RACHP) industry, equivalent to 40 % of total annual refrigerant emissions, despite it being responsible for only 22 % of worldwide refrigerant consumption.
Annual leak rates can be an average of 11 % and up to 30 % in some cases. Leakage data from 1 464 maintenance records were analysed. The analysis categorised the type and location of each leak and the volume of refrigerant replaced during repair. Over 82 % of the recorded leaks were from R404A refrigeration systems, and mainly advantagemechanical. com consisted of pipe or joint failures or a leaking seal / gland / core located in the compressor pack and the high-pressure liquid line.
The authors recommend that the industry focuses on developing leak tight design, installation, and maintenance of pipework and valves for the components that most often develop faults to minimise refrigerant leakage.
Source: C. Francis; G. Maidment; G. Davies. February 2017. An investigation of refrigerant leakage in commercial refrigeration, International Journal of Refrigeration, vol. 74.
Leakage data from 1 464 maintenance records were analysed.
COLD-STORAGE FACILITY CONVERTED TO PROPANE IN COLOMBIA
Asocolflores, the association representing flower exporters in Colombia, has replaced an R22-based system with R290 in a 392m 2 cold-storage facility for flowers, located in the Savanna of Bogota. us. jll. com
Asocolflores has replaced an R22-based system with R290 in a 392m 2 cold-storage facility for flowers in Columbia.
The performance of the system was analysed and results showed that R290 provides 10 % less of cooling capacity, but increases the coefficient of performance( COP) and reduces energy consumption by at least 10 %. To address safety concerns such as system pressure and refrigerant flammability, Asocolflores put in place several measures. In particular, an analysis on flammability based on the EN 378:2008 safety standard for refrigeration systems and a basic risk assessment under EN 1127-1:2011 was achieved. Assuming a 10kg charge of R290, the maximum concentration level would be 25g / m 3. The high charge is acceptable because the room is only accessible to authorised staff. Finally, technicians were trained to safely handle hydrocarbons.