International. An article published by SAE International compares the electrical energy consumption of two mobile air conditioning systems in battery-electric vehicles. In each case, CO2 (R744) was compared with another refrigerant:
System 1: Conventional cooling cycles with positive temperature coefficients (PTC). Comparison of R744 and R1234yf.
System 2: Reversible heat pumps. Comparison of R744 and R134a.
Figure 1. Refrigerant table.
The study is based on a thermal vehicle simulation that considers driving times between 06:00 hours and 24:00 hours and takes into account 6 different temperature ranges. Relative humidity and solar radiation are also taken into account and correspond to data from 211 cities around the world (located in Europe, America, Asia, Africa).
The simulation is based on GREEN-MAC-LCCP data, which is a model used to calculate and predict the life cycle of greenhouse gas emissions for refrigerants used in mobile air conditioning.
According to this study, the reversible heat pump system is the most energy efficient. Of the two refrigerants considered, R744 leads to lower electricity consumption (311TWh per year) than R134a (320 TWh per year). The difference would be even more significant in cold climates.
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