Locomotives and Rail Road Transportation

Development of locomotive and advancement of rail road transportation is important for reducing emissions and becoming less dependent on conventional fossil fuels. Utilization of available alternative fuels such as methanol, DME and biodiesel can resolve energy crises in the foreseeable future. Effective use of exhaust heat recovery can be helpful in increasing overall efficiency and power generation. After-treatment devices are now a necessity to meet the upcoming emission norms for the rail road sector. For meeting the challenges of energy and environment, there is a need for advanced technological development in locomotive and rail road transportation sector.

In this article, we would like to trace the history of the growth of diesel traction of Indian railways without completely sacrificing technical details. It starts from the very early times and discusses at length the coming of the ALCO locomotives on the Indian Railways (IR) and the reappearance of EMD locos on IR. We have tried to mix the historical facts with technical facts therefore calling the study presented in this paper as technical history.

Even by conservative estimates more than 20% fuel energy from internal combustion engines is wasted as exhaust heat. Currently organic Rankine cycles and thermoelectric generators are most widely investigated options for automobile exhaust heat recovery. Use of thermoelectric generators for recovery of exhaust heat in automobiles at concept level started few decades ago. Major advantages of this technology over Rankine cycles are little noise and vibration, high durability, environmental friendliness, and low maintenance cost for converting low quality thermal energy directly into high quality electrical energy. Major challenges are lower efficiency (~8%), drop in efficiency at lower temperatures, performance optimization in synchronization with multiple constraints of after-treatment devices, silencer, back pressure reduction, turbo-charging etc. Larger size of diesel locomotives compared with space available for automobile engine’s mounting on vehicles makes the installation of exhaust heat recovery system in diesel locomotives more practical. In this paper, feasibility and suitability of various exhaust heat energy recovery methods for diesel locomotives has been discussed.

Diesel locomotives are the mainstay of modern railway systems. Despite the fact that they are noisy and polluting compared to electric locomotives, they continue to remain popular across the world. This is because they can run in areas where electric supply is either unavailable or unreliable, and also because in times of war their service does not get affected even if electric power lines get damaged. Since most railway networks cut across highly populated areas, efforts have to be made to ensure that diesel engine noise is reduced to a minimum. In this chapter this need has been addressed. Specifically, the chapter explains the working of a modern diesel engine locomotive in brief. Such an understanding is important, as all noise generating mechanisms in a diesel locomotive are tightly coupled with its working. Next, different types of noise emanating from a diesel locomotive have been described. Such a description will help the reader assess the nature of each noise component in terms of its magnitude and its frequency spectrum.  Next a method to develop noise reduction strategy of diesel locomotive noise is proposed. Next, the chapter explains a diverse suite of noise reduction methods. These methods can be passive or active. The range of passive methods is fairly large. All these methods have been described in detail. This is followed up with a description of important regulations related to locomotive noise. Finally, an exhaustive list of relevant international standards has been provided. These references will be very useful to the reader if she is involved with reduction of train and locomotive noise.

Indian Railways (IR) have a fleet of 5000 diesel locomotives and this population is growing at a rate of 200 locomotives per year. Diesel expenditure on IR is ~Rs. 20,000 Crore per year (US$ 4 bn/Y), which is ~10% of the turnover of the IR. This is the main motivation for both, reducing this expenditure as well as replacing diesel with domestically produced alternate fuels. With this objective, Engine Development Directorate (EDD) of Research Designs and Standards Orgaisation (RDSO) has carried out engine studies using different indigenously produced biodiesels on two locomotive engines on engine test benches. Details of these engine studies and scope for future research on use of biodiesel for rail road traction are discussed in this chapter.

The purpose of this article is to provide the physicochemical properties and characteristics of exhaust emissions from a DME-fueled diesel engine. Fundamental properties of DME are described and compared with the properties of the conventional diesel fuel. In addition, the applicability of DME fuel is presented in terms of its potentials as an alternative fuel for compression ignition engines. The exhaust emission characteristics of a DME-fueled engine are described using experimental results of different DME and diesel blends. The most important properties of DME are the presence of oxygen in the fuel molecule, lower ignition temperature, and high cetane number. The kinematic viscosity of DME is significantly lower than that of diesel. However, low lower hating value (LHV), low viscosity, and low lubricity are some of the major disadvantages of DME. The bulk modulus of DME is about 1/3 compared to diesel fuel. Spray tip penetration of DME is found to be shorter than that of diesel. Also, the Sauter mean diameter (SMD) distribution of the DME spray is found to be much smaller than that of diesel. Emission characteristics of different DME and diesel blends are investigated, which shows low soot, CO, and other hydrocarbon emissions.

Locomotives are critical for the economic development of India. Majority of locomotives of Indian Railways (IR) are diesel-electric locomotives. While these locomotives offer significant flexibility and ease of operation, they have significant challenges as well such as imported fuel consumption. As the fossil fuel resources are dwindling at an alarming rate, there is a need to explore alternative fuels such as DME and Methanol, whose potential for this applications largely remains unrecognized in India. Dependence on imported petroleum can be significantly reduced by these alternative fuels. In this chapter, technical feasibility, opportunities, challenges and potential of DME and Methanol as locomotive fuels in India is discussed. These fuels are low-emission fuels, which have been overlooked in both energy policy and industry discussions, despite many attributes, which make them attractive. DME is especially suitable in diesel locomotives due to its excellent fuel characteristics. Motivation to use DME as a candidate fuel in locomotives in India comes from its soot-free emission due to absence of C–C bonds. It can be also be blended with mineral diesel to overcome limitations of using pure DME, which include low viscosity and density. Similarly, Methanol can be blended with diesel for use in locomotives. Methanol has a high latent heat of vaporization; higher oxygen content, is sulfur free and has higher burning speeds than conventional liquid fuels. When burned at high temperature, it can reduce smoke and oxides of nitrogen (NO_x) emissions from compression ignition (CI) engines. However, there are limitations in the development of pure Methanol CI engines. Such limitations have been highlighted in this chapter and partial replacement of diesel by DME and Methanol are proposed as a solution for locomotives. Modifications to prevent corrosion and overcoming issues such as low lubricity in fuel injection systems is also discussed in detail.

Indian Railways (IR) operates a large fleet of Diesel Locomotives. In recent times, a concerted effort is being made to understand the emission implications on the environment from these locomotives and its remedial measures. This article reviews the global standards for diesel locomotive emission norms and available after treatment solutions for diesel locomotives. Currently, there are no emission norms defined in India for locomotives and may be considered in future. The Diesel after treatment solutions include Diesel Oxidation Catalysts (DOC), Diesel Particulate Filter (DPF) and Selective Catalytic Reduction (SCR) systems. Initially, it may be advisable to employ only DOC solution on diesel locomotives of IR followed by a thorough study of emissions on representative routes. Such a study would yield data for a design of a complete after treatment solution.

Diesel engines have gained an edge over other fuel engines in heavy duty transportation sector owing to their high efficiency, high durability and reliability with low operational costs. Also, in the last few decades, diesel engines have chunked out a growing share in the light-duty vehicle market as well.

The present study aims at understanding the influence of differential diffusion on the evolution of flow field and soot volume fraction. For this purpose, two different turbulent diffusion flames (Delft flame III, pilot stabilized natural gas flame and an unconfined turbulent lifted ethylene/air jet flame) are investigated for flow field and soot predictions. The presumed shape multi-environment Eulerian PDF (EPDF) is used as turbulence-chemistry interaction model, while the radiative heat-transfer equation is modeled based on the truncated series expansion in spherical harmonics (P1 approximation). Two approaches are used to model diffusivity, a unity Lewis Number, and multi-component diffusion approach. For predicting soot evolution, an acetylene-based semi-empirical model (Moss-Brookes model and Method of Moments (MOM) model is used. Both the models consider the inception, surface growth and oxidation processes of soot. The influence of temperature is included in terms of the effective absorption coefficient and turbulence-chemistry interaction effects are included in terms of a single variable PDF in terms of temperature. The predictions elucidate the influence of temperature on soot volume fraction. Differential diffusion results in an increase in the soot volume fraction.

In a historic judgment the National Greens Tribunal of India has stipulated that Indian Railways should specify emission standards for diesel locomotives of Indian Railways and implement technologies to reduce these pollutants from diesel locomotives in a time bound manner. In order to decide on the emission standards, it is essential that an emission inventory of the diesel locomotives be obtained from across different areas, working environments, different configurations and age groups. Indian Railways has a population of about 5000 diesel locomotives and 56 diesel sheds and it is not possible to establish mass emission measurement systems at all diesel sheds because of the high cost of these measurement systems as well as a scientific group of personnel required for carrying out these measurements as per International standards like US EPA and Europe UIC. Both of these international emission standards stipulate mass based measurements of the pollutants in order to arrive at the emission levels of a diesel locomotive. Engine Development Directorate at Research Designs & Standards Organisation (RDSO) has setup mass emission measurement systems at RDSO for measuring emissions from test engines. At least, 100 diesel locomotives are required to be measured from different areas, configurations, age groups, etc. in order to arrive at statistically significant upper and lower control limits. It is not physically possible to bring these 100 locomotives to Engine Development Directorate at RDSO, therefore a mobile emissions test car was designed and manufactured by Indian Railways. This mobile emission test car is capable of measuring mass emissions from the diesel locomotives as per the International standards. This chapter discusses the process of how this mobile emission test car was envisaged and manufactured. This included the layout, selection of the equipments and ease of operation so as to meet the international emission measurement standards.