Empirical Study on the Efficiency of an LPG-Supplied Range Extender for Electric Vehicles

Abstract

A range extender is an auxiliary power unit, usually consisting of an internal combustion engine and an electric generator, which is used to charge a battery of an electric vehicle in order to increase its range. This paper considers a range extender supplied with liquefied petroleum gas (LPG). The aim is to provide detailed data on thermal efficiency, brake specific fuel consumption (BSFC), and unit emission of carbon dioxide (CO 2 ) in a broad spectrum of range extender operating conditions defined by rotational speed and torque. The experimental investigation has been conducted using a laboratory test stand equipped with an energy dissipation system of adjustable resistance. Measurement results, including fuel flow rate, were processed using custom algorithm for generating maps, i.e., two-dimensional dependencies of the considered parameters on the rotational speed and torque. The maps obtained for LPG supply were compared with those for gasoline supply. The results demonstrated feasibility of LPG-supplied range extender. Its BSFC and thermal efficiency were at a comparable level to those obtained for gasoline supply, but with less CO 2 emission. The empirical data collected has been adopted in the simulation of extended-range electric vehicle in a driving cycle, showing the potential of utilizing the results of this study.Energies 2019, 12, 3528 2 of 23 ( Figure 1). Their principle of operation is same as that of a standard BEVs, with the only difference being that an additional ICE acts as an on-board generator (range extender) to recharge the battery [11]. EREVs operate exclusively as BEVs when battery energy is available and have full performance in electric mode (e.g., top speed, acceleration capability) [12]. This is possible owing to EREV's electric propulsion system and battery sized in such a way that the ICE is not required for vehicle operation as long as battery energy is available [12]. It is therefore preferable to move the vehicle with the use of an electric motor only, i.e., in "zero emission" driving mode, but at the same time, the user is not afraid of running out of battery energy, and so called "range anxiety" (the term was introduced in the late 1990s [13]) is alleviated.Energies 2019, 12, x FOR PEER REVIEW 2 of 25 being that an additional ICE acts as an on-board generator (range extender) to recharge the battery [11]. EREVs operate exclusively as BEVs when battery energy is available and have full performance in electric mode (e.g., top speed, acceleration capability) [12]. This is possible owing to EREV's electric propulsion system and battery sized in such a way that the ICE is not required for vehicle operation as long as battery energy is available [12]. It is therefore preferable to move the vehicle with the use of an electric motor only, i.e., in "zero emission" driving mode, but at the same time, the user is not afraid of running out of battery energy, and so called "range anxiety" (the term was introduced in the late 1990s [13]) is alleviated.

Analysis of the strategies for managing extended-range electric vehicle powertrain in the urban driving cycle

“…The ICE of the REX worked at a single operating point, selected taking into account the two-dimensional efficiency characteristic (map) determined earlier [14].…”

“…Extensive research on electric vehicles has been carried out at the Faculty of Automotive and Construction Machinery Engineering of the Warsaw University of Technology. Recently, much attention has been paid to EREVs, which results in publications [14][15][16]. Current paper presents the results of testing extended-range electric powertrain in laboratory conditions.…”

The comparison of gasoline powered vehicle and serial hybrid vehicle on emissions

“…The study also showed that engine performance could be further improved and fuel consumption reduced while meeting EURO-VI emissions regulations with appropriate advanced injection timing. Lasocki et al empirically studied the efficiency of a range extender unit with liquefied petroleum gas (LPG) and gasoline [ 24 ]. Collected data has been used in the simulation of an extended-range electric vehicle in a driving cycle.…”

Research on low-emission vehicle powered by LPG using innovative hardware and software

“…This can be achieved by feeding the internal combustion engine of the hybrid vehicle with a gaseous fuel, for example LPG. Scientists are considering a range extender for electric vehicles to also run on LPG [25].…”