Using Air Walls for the Reduction of Open-Door Heat Losses in Buses

A vital contribution for the development of an environmental friendly society is improved energy efficiency in public transport systems. Increased electrification of these systems is essential to achieve the high objectives stated. Since the operating range of an electrical vehicle is heavily influenced of the available energy, which primarily is used for propulsion and thermal passenger comfort, all heat losses in the vehicle systems must be minimized. Especially for urban buses, the unwanted heat losses through open doors while passengers are boarding, have to be controlled. These energy fluxes are due to the large temperature gradients generated between in- and outdoor conditions and to install air-walls in the door opening areas have turned out to be a promising technical solution. Based on air-wall technologies used for climate control in buildings, this paper presents an experimental investigation on the reduction of heat losses in the door opening of urban buses. Devices for creating the air-wall were located on top of the door opening of an articulated bus of Dresden public transport service DVB AG. Measurements of temperatures were conducted using distributed NTC-sensors. An extensive measuring program was performed and it was found that the air walls had a significant influence on the energy exchange process. On a short door opening time the energy losses increased, while for longer door opening times major reduction on the energy losses were achieved.Cross Reference: