This paper investigated cooling and heating performance of a heat pump for an electric bus with a coolant source using the wasted heat of the electric devices for heating and an air source for cooling. Especially, the heat pump was designed to make maximum use of the exhaust heat from the electric devices. Both cooling and heating performance characteristics of the heat pump using R-134a were experimentally investigated under various experimental conditions including variations of outdoor and indoor temperatures, the water flow rate for the condenser and evaporator sides. Then, these parameters were optimized by varying the refrigerant charge and the compressor frequency. The cooling capacity increased by 9.71 % but the cooling COP decreased by 14.17 % with the increase of the outdoor temperature due to the rise in compressor work. The cooling capacity increased by 8.54 % with the increase of the indoor temperature and the cooling capacity increased by 5.19 % with the increase of the compressor frequency. The cooling capacity at all compressor frequencies was over 23.0 kW sufficient for the cooling loads of an electric bus operated on a refrigerant charge of 8200 g in outdoor and indoor temperatures of 27.0 °C and 35.0 °C, respectively. The heating COP decreased but the heating capacity increased with the rise of the outdoor temperature and compressor frequency. The heating COP was 2.4 at the outdoor temperature of 10.0 °C and a sufficient heating capacity of over 23.0 kW at all tested compressor frequencies and outdoor temperatures. The air average temperature of the heater core outlet with the 2 PTC heaters was 25.0 °C after 10 min and increased up to a maximum of 51.7 °C. The average temperature of the 6 heater core units with the 2 PTC heaters was on average 6.0 °C higher than that of the 6 heater cores units without the PTC heaters. In addition, in both steady state and transient state, the observed heating performance characteristics of the heating capacity over 23.0 kW, the heating COP over 2.1, and transient air warm-up speed of the heat pump for a heating could be sufficiently used as the cabin heater for an electric bus which suffers from a short driving range.
Performance characteristics of mobile heat pump for a large passenger electric vehicle
Applied Thermal Engineering ; 50 , 1 ; 660-669
2013
10 Seiten, 11 Bilder, 3 Tabellen, 21 Quellen
Article (Journal)
English
experimentelle Untersuchung , Wärmepumpe , Leistungswert , Elektrobus , Kühlleistung , Kältemittel , Temperatureinfluss , Luftkühlung , Abwärme , Verdichter , Parameteroptimierung , Außentemperatur , Wasserströmung , Flüssigkeitsgeschwindigkeit , Verdampfer , Kondensator (Wärmeübergang) , Fahrzeugklimatisierung