Abstract
In the present paper, the first results of an experimental analysis carried out to assess the performance of a water-to-water heat pump in which R1234yf and R1234ze(E) are used as drop-in substitutes of R134a are shown. The heat pump is first tested with R134a to establish a baseline performance and, then, is tested under the same working conditions, i.e. under the same water temperatures at evaporator and condenser outlets, with the above-mentioned HFO refrigerants. The results show that the heating capacity and COP of R1234yf system are up to 9.8% and 6.1% respectively lower than those obtained with R134a. On the other side, the use of R1234ze(E) leads to a capacity reduction and a COP reduction respectively up to 23.1% and 2.5%. A second set of tests is then carried out varying the rotational frequency of the compressor shaft in order to set the heat pump heating capacity to the same value found with R134a. The experimental results demonstrate that increases up to 17% and 50% are respectively needed for R1234yf and R1234ze(E), but subsequent reductions of heat pump COP up to 7.38% and 18.11% arise.
Highlights
The recent EU 517/2014 regulation [1] and the Kigali amendment [2] have introduced constraints that force the air conditioning and refrigeration industry to find new refrigerants able to cope with more and more severe limits on Global Warning Potential (GWP)
Navarro-Esbrí et al [4] carried out an extensive experimental analysis of the use of R1234yf in waterto-water vapour compression system in a drop-in application
They analysed the influence of evaporating temperature, condensing temperature, internal heat exchanger use, superheating degree and compressor drive frequency
Summary
The recent EU 517/2014 regulation [1] and the Kigali amendment [2] have introduced constraints that force the air conditioning and refrigeration industry to find new refrigerants able to cope with more and more severe limits on Global Warning Potential (GWP). Navarro-Esbrí et al [4] carried out an extensive experimental analysis of the use of R1234yf in waterto-water vapour compression system in a drop-in application. They analysed the influence of evaporating temperature, condensing temperature, internal heat exchanger use, superheating degree and compressor drive frequency. They found that the use of R1234yf leads to an overall reduction of the cooling capacity, in the range 4.36% - 13.46%, and of the COP, in the range 5.60% - 27.89%, with larger differences at low evaporating or condensing temperatures. R1234yf benefited more than R134a from the use of internal heat exchanger while the influence of different superheating set-points or different compressor drive frequencies was negligible
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