SAE Alternate Refrigerant Systems Symposium The 4 Fiat Pandas Experiment and other considerations on refrigerants C. Malvicino CENTRO RICERCHE FIAT carloandrea.malvicino@crf.it
Conclusions A year 2000 R-134 MAC system can be easily improved to halve the energy consumption HFO (R-1234yf) is almost a drop in but needs improvements and flammability issue has to be considered The R-744 system achieves the same energy performance of a year 2000 R-134 MAC, but further improvements are expensive The secondary loop architecture is a promising solution especially in perspective of the incoming Stop & Start and next generation power-trains 2
Summary Vehicle Description Baseline Enhanced R-134a HFO (R-1234yf) R-744 R-152 and secondary loop Test procedures Tests Results Cool Down Fuel Consumption Cost Estimation Final Considerations Other Relevant Facts What s Next: a proposal for a new MAC concept 3
Baseline System EVAPORATOR: 185 x 188 x 58 Plates and Fins 60 cc SCROLL COMPRESSOR TAU: 1.32 Air Flow CONDENSER 574 x 315 x16 Serpentine Parallel Flow with integrated dryer Min Mean Max m 3 /h Cabin Volume (l) Front 1143 Back 1107 Boot 184 Total 2434 Fluid-dynamic characteristics measured @ 13.95 Voltage supply with no-recirc Mode Vent 84 177 325 Cooling Def 71 146 264 Heating Floor 65 142 256 Heating 4
Fiat Panda position on a Fuel Overconsumption chart 2.5 EUDC Overconsumption (l/100 km) 2.0 1.5 1.0 0.5 0.0 Fiat Panda 0.0 2.0 4.0 6.0 8.0 ECE Overconsumption (l/100 km) Test @ 28 C Test @ 35 C Panda 28 C Panda 35 C 5
Enhanced R-134a Energy Saving controlling the scroll compressor on-off threshold Humidity management Internal Heat Exchanger (IHX) REJECTED HEAT CONDENSER COMPRESSOR Refrigerant Loop Internal Heat exchanger Supported by UNEP, EPA and Fiat Group Automobiles EVAPORATOR EXPANSION DEVICE ENGINE BAY CABIN COOLING POWER 6
Low Cost Energy Saving 30 25 T Evaporator NP T Vent NP T Head NP T Evaporator ES T Vent ES T Head ES Same Head level temperatures Temperature [ C] 20 15 10 5 Equivalent outlet temperatures The Energy Saving algorithm controls the produced cooling power to fit the comfort requirements by means of the modulation of the compressor on-off threshold 0 500 700 900 1100 1300 1500 1700 1900 Time [sec] Energy saving: the cooled air temperature is adjusted modulating the on-off threshold so to minimise the re-heat and the energy waste The Standard system produces always the maximum cooling power and then the cooled air is heated to produce the required outlet temperature Standard system: the cooled air temperature is always of about 4 degrees and then is reheated to meet the comfort requirements 7
Low Cost Energy Saving l/100km 1.0 0.5 IHX ES Strategies Energy Saving 15 Temperature ( C) 35 8
HFO (R-1234yf) No changes to the original MAC HFO features: GWP: 4 Critical temperature: 94 C Flammable Not Toxic (still under evaluation) COMPRESSOR CONDENSER Refrigerant Loop REJECTED HEAT EXPANSION DEVICE ENGINE BAY EVAPORATOR CABIN Supported by Fiat Group Automobiles COOLING POWER 9
R-744 (CO 2 ) B-COOL Project Energy Saving controlling the compressor displacement Internal Heat Exchanger (IHX) Supported by the European Union VI Framework 10