Title: Technical Report: Design and operation of a new transportable laboratory for emissions testing of heavy duty trucks and buses

Authors: Nigel N. Clark, Mridul Gautam, Reda M. Bata, Wen-Guang Wang, John L. Loth, G. Michael Palmer, Donald W. Lyons

Addresses: Dept. of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV 26506-6106, USA. ' Dept. of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV 26506-6106, USA. ' Dept. of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV 26506-6106, USA. ' Dept. of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV 26506-6106, USA. ' Dept. of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV 26506-6106, USA. ' Dept. of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV 26506-6106, USA. ' Dept. of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV 26506-6106, USA

Abstract: A significant number of city buses, city tractors and utility trucks are already operating on alternative fuels such as methanol, ethanol and natural gas. In response to the need for reliable emissions data from these vehicles, a transportable laboratory has been constructed and has operated on six different dates over the past nine months. This laboratory consists of a semi-trailer incorporating a chassis rolls dynamometer and a second trailer containing the necessary emissions and controls equipment. The semi-trailer can be lowered to the ground using specially designed hydraulic jacks and the vehicle to be tested is driven up ramps onto the rolls. Power is taken from the vehicle to flywheels and air-cooled eddy-current absorbers which simulate inertia and road load. The vehicle is driven through a speed-time cycle by a driver receiving a prompt on a screen, and vehicle speed is monitored by shaft encoders at three locations. The load applied to the vehicle is found using a road load equation: part of this energy is dissipated in rotating component parasitic losses determined during a calibration procedure and the remainder is dissipated by the computer-controlled power absorbers. Tailpipe emissions are ducted to a dilution tunnel, powered by a blower with critical flow venturies, while probes in the tunnel draw continuous samples to an analyser bench. Total hydrocarbons, oxides of nitrogen, carbon monoxide and carbon dioxide are all monitored, while a composite particulate matter sample is obtained on a filter. A bank of such data for methanol, diesel, jet fuel and natural gas powered buses operating primarily on the Central Business District Cycle is presently being gathered and analysed.

Keywords: buses; emissions testing; heavy vehicles; transportable laboratory; laboratory design.

DOI: 10.1504/IJHVS.1995.054615

International Journal of Heavy Vehicle Systems, 1995 Vol.2 No.3/4, pp.308 - 322

Available online: 18 Jun 2013 *

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