Browsing by Author "Hirvensalo, Iiro"
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Helsinki University of Technology | Master's thesis(1973) Hirvensalo, Iiro - Utopia or Opportunity? - Predicted Performance of 21st Century Technology Steam Locomotives
School of Engineering | Doctoral dissertation (monograph)(2021) Hirvensalo, IiroThe objective of this study is to predict the performance of liquid fuel burning steam locomotives based on the technology available today. Diesel engine tribology, electronic valve control, and substantially higher steam parameters than those of classic steam locomotives have been applied. Such locomotives have not been built yet but appear to offer promising possibilities. A hypothetic pattern locomotive called Hs1 has been configured, to predict the performance of such locomotives. Several methods have been used for virtual creating and testing of the Hs1. Firstly, the evolution of classic steam locomotives has been discussed in terms of their strengths and weaknesses, with resulting pre-requisites from potential customers for any steam power. Secondly, classic, and recent literature has been studied in search for advances in steam- and other applicable technologies, materials, and practices. Thirdly, innovative experimental locomotive designs have been discussed. Fourthly, properties and adaptability of bio-oil vs. fossil oil as fuels have been discussed. Finally, enginemen's know-how has been exploited, to include practical and operational views in the design of the Hs1. Conclusions of the findings within the discussions constitute the basic specifications of the Hs1. A radial reciprocating steam engine is opted for the prime mover, with a turbine to recover the energy of the exhaust steam of the radial engine, and with an electrical transmission to power the driving wheels. The power chain downstream of the prime mover is thus identical with that of diesel-electric locomotives. Diesel components have been exploited to unify the operational and maintenance characteristics of the Hs1 with those of diesel-electric locomotives. Electric transmission enables recovery of energy generated by the traction motors in dynamic braking by storing it into accumulators or by feeding resistors that heat the feedwater. A simulation program has been created for assessing the performance of the Hs1, and for comparing the figures with those of a reference diesel-electric locomotive as well as of a classic steam locomotive. Road test simulations predict a drawbar efficiency of 21-27 % for the Hs1, depending on whether and in which way the braking energy is recovered, and 33 % for the reference diesel-electric locomotive. The simulated classic steam locomotive attains 6,5-7 % at the maximum in the same assignment, the round-the-year figures being 3-4 %. Yard work involves a lot of braking and thus potential for recovery of braking energy, resulting in predicted drawbar efficiency of 29-36 % for the Hs1 vs. 33% of the diesel electric locomotive. In light passenger trains with frequent stops, the Hs1 is predicted to attain an efficiency of 18-29% vs. 33 % of the diesel-electric locomotive. Bio-oil combustion enhances the sustainability of the Hs1 as motive power when compared with engines dependent on fossil fuel. External combustion enables exploiting lower grade pyrolysis oil that would require further refining to make it fit for internal combustion engines. The CO2 emissions of diesel engines originate from fossil fuel unless 100 % bio-oil is used whereas the fuel of Hs1 is made of forest residue releasing its CO2 content even if left in the woods.