Head End Power Research Articles

Portable Emission Measurement System for Emissions of Passenger Rail Locomotives

The purpose of this study was to demonstrate a method for measuring passenger railroad locomotive emissions with the use of a portable emission measurement system (PEMS) based on rail yard load tests of three locomotives, including one GP40 and two F59PHIs. These locomotives have mechanically governed diesel prime mover engines (PMEs) with an approximately 3,000-hp output. Each locomotive has a head end power (HEP) engine that produces approximately 600 hp for generating electricity used in the passenger cars. The engine measurements were based on ultralow sulfur diesel fuel. Each engine was instrumented to measure manifold absolute pressure, engine revolutions per minute, intake air temperature, and exhaust concentrations of selected gases and particles. These data were used to quantify exhaust and fuel flow. The exhaust concentrations of nitric oxide, carbon monoxide (CO), carbon dioxide, hydrocarbons, and particulate matter were measured. The PMEs are operated at each of many throttle notch settings. For the HEP engines, three electrical loads were applied on the basis of power usage for one, two, and four passenger cars, respectively. More than 97% of the raw data survived a multistep quality assurance process. The data obtained from the PEMS for the main engines were found to be comparable on a fuel basis to data reported by others, particularly for oxides of nitrogen and CO. The key results from this work are the establishment of a simplified methodology for future tests and the development of baseline data.

Economics of Commuter Rail Alternatives: Comparative Cost Perspective

In the North American commuter rail environment, authorities planning to commence or expand service have several rolling stock options to evaluate. In the nonelectrified mixed-traffic operating environments that are prevalent outside the northeastern United States, locomotive-hauled vehicles—diesel-electric locomotives with head-end power units used in push-pull operation with single- or multiple-level coaches—have traditionally been the equipment of choice. With the imminent reemergence of a diesel multiple unit vehicle compliant with FRA standards for mixed traffic operation, the available equipment options have expanded. Authorities must be provided with the required information to evaluate and compare the costs and benefits of this newly available option. The true direct costs (excluding track access fees and insurance; justification for the exclusion of these issues is included) associated with the life cycle of rail vehicles are evaluated to provide transit authorities with the information required to make informed procurement decisions.

Diesel Locomotive Retrofit: Conceptual Design with Twin Turbines Reduces Overall Emissions

The fine particulate matter component of diesel engine exhaust has been declared by the state of California to be a human carcinogen at any concentration and is therefore subject to measures for its reduction or total elimination. The diesel locomotive contribution to this problem is projected to be 46% of the total particulate tonnage from diesel engines in California in 2010. A conceptual design substitutes gas turbines for the main traction engine and head-end power (HEP) engine of a typical diesel electric commuter locomotive. Retaining the existing HEP engine while replacing the traction engine also is evaluated. Relying on burning conventional diesel No. 2 fuel oil, the conceptual design is projected to significantly reduce or eliminate measurable particulate matter and significantly reduce other exhaust pollutants. Because the gas turbine readily adapts to natural gas as a fuel without any loss in performance, the economics and additional emissions benefits also will be developed for the use of liquefied natural gas.

Head end power on railroad passenger trains

THE IDEA of concentrating electric energy generation at one point in a train, on or behind the locomotive, becomes increasingly attractive with the increase in electric loads on modern passenger cars. The advantages and disadvantages of head end power against those of the conventional d-c axle generator storage battery equipments have been considered. In favor of head end power were simplicity of installation and maintenance, reliability, and elimination of parasitic axle generator drag. The principal argument against head end power lay in its lack of operating flexibility. All cars in such a train must be wired for trainline operation, so that no other cars can be added.