ABSTRACT Indian Railways have a fleet of high-horsepower diesel- electric locomotives rated at 2310 kW. These high horsepower diesel-electric locomotives have evolved from original design of 1940 kW locomotives. Adoption of new design turbochargers was essential for this upgrading efforts and a series of new design turbochargers were evaluated on the engine test-bed before their use on the diesel locomotives. The objective was to increase engine power output, improve fuel efficiency and limit thermal loading. Test-bed evaluation of different turbochargers was carried out for comparing five different turbochargers. Each turbocharger had different size nozzle ring, diffuser, turbine blade assembly, impeller and inducer. The compressor maps of turbochargers were used to plot the engine load lines and to calculate surge margins. The tests involved measuring critical parameters for various combinations of engine speed and load for every turbocharger. Some of these measured parameters were air inlet temperature to the compressor, peak firing pressures, inlet temperature to the turbine, cylinder head temperature, brake specific fuel consumption (BSFC), engine boost and air manifold temperature. This paper discusses the methods adopted for carrying out these evaluations and the results obtained thereof along with the decision criteria for making final selection of turbocharger for locomotives. INTRODUCTION Indian Railways (IR) has the distinction of being the largest railway system in the world under a single management. Railways being the most energy efficient transportation mode, are ideally suited for movement of bulk commodities and for long distance travel in the length and breadth of the nation. Railways are five-to-six times more energy efficient, four times more efficient in land usage and significantly superior from environmental impact and passenger safety point of view. As the principal constituent of nation's transport system, Indian Railways owns a fleet of 8000 locomotives; more than half of which are diesel-electric locomotives, with the remaining being electric locomotives. IR is operating locomotives, which were originally designed six decades ago and there is a need to produce more power output from these old design workhorses. Therefore IR have been evaluating different designs of turbochargers for their fleet of high horsepower diesel-electric locomotives to improve their power output from the same power-train and simultaneously reduce fuel consumption. As part of this exercise, various designs of turbochargers were evaluated for their performance and matching with the existing locomotive engines. The 2310 kW diesel-electric locomotive engine is a sixteen cylinders, four-stroke, ‘V’ configuration, air-water after- cooled, turbocharged engine with a partially constant pressure exhaust manifold (having a single manifold for fourteen cylinders and two cylinders feeding directly into the three entry turbocharger gas casing). The locomotive engine turbochargers are combination of single stage centrifugal compressor and a single stage axial flow turbine. The compressed air is after-cooled before induction into the combustion chamber. Technical specifications of the test engine for present investigations are given in Table 1. Present research was undertaken for comparative evaluation of different turbochargers on this engine. The prime objective of this research was to employ these advanced turbochargers with the existing engines of Indian Railways along with evaluation and optimization of the engine performance. Comparative Evaluation of Turbochargers for High Horsepower Diesel-Electric Locomotives 2013-01-0930 Published 04/08/2013 Anirudh Gautam and Avinash Kumar Agarwal I I T Kanpur Copyright © 2013 SAE International doi: 10.4271/2013-01-0930 THIS DOCUMENT IS PROTECTED BY U.S. AND INTERNATIONAL COPYRIGHT. It may not be reproduced, stored in a retrieval system, distributed or transmitted, in whole or in part, in any form or by any means. Downloaded from SAE International by Anirudh Gautam, Sunday, April 07, 2013 10:12:55 AM