New refrigerants for vapour compression refrigeration and heat pump systems
Time: Tue 2019-09-24 13.00
Subject area: Energy Technology
Doctoral student: Pavel Makhnatch , Tillämpad termodynamik och kylteknik
Opponent: Associate professor Angelo Maiorino, Department of Industrial Engineering DIIN, University of Salerno
Supervisor: Professor Rahmatollah Khodabandeh, Tillämpad termodynamik och kylteknik
Given the global commitment to reduce the impact of fluorinated gases on climate and the regulations controlling their use in the European Union (EU), this thesis investigates new refrigerants that have been recently proposed to meet the demands of the refrigeration industry in the EU, which must satisfy the legislative requirements of the F-gas Regulation and facilitate meeting the goals of the Paris Agreement.
The legislative requirements of the EU have intensified refrigerant development with reduced GWP. New refrigerants have been identified in the form of six new substances and 40 new refrigerant mixtures that have been added to the ANSI/ASHRAE 34 standard during a period following the proposal for the F-gas Regulation.
New refrigerants have been theoretically analysed in comparison with the commonly used fluorinated refrigerants R134a, R404A and R410A. While new refrigerants provide a variation in operating parameters when used in a refrigeration, air conditioning or heat pump (RACHP) system, none of the new refrigerants can be considered being fully design compatible with R134a, R404A or R410A.
Several commercially available refrigerants have been further evaluated in experimental studies to analyse their suitability for replacing R134a and R404A in existing systems with regards to their thermal properties, requirements for component safety and energy efficiency. R450A and R513A have been analysed as alternatives to R134a in a small capacity refrigeration system, and an R449A was studied in a retrofit of an R404A supermarket indirect system. It was shown that the analysed refrigerants can replace baseline HFCs in the analysed systems, but the variation in energetic performance and main operation parameters should be taken into account when considering such replacement.
LCCP metric has been used to analyse the overall climate impact of a heat pump system using refrigerants with various GWP values. It was shown that most climate impact from an RACHP system is due to indirect emissions relating to energy use. Thus, addressing the overall climate impact of RACHP systems is necessary to facilitate meeting the goals of the Paris Agreement. It is possible to facilitate a comparative LCCP analysis by addressing the uncertainties of the input data.