POSSIBLE METHODS OF IMPROVING ENGINE OVERALL THERMAL EFFICIENCY

Waste-heat recovery in Diesel installations, by using the exhaust gases to raise steam for driving turbo- alternators, has had few applications in ships' four-stroke medium-speed installations because of its cost and complexity. However, the number of such applications is expected to increase as a result of high fuel prices. In cases where the electrical power thus generated is not enough for the ship's needs, the lubricating-oil and water pumps can be driven off the engine itself or through the reduction gear; the energy recovered from the exhaust gases may then be sufficient to cover the electrical requirements. Where maximum energy recovery is required from the exhaust gases, a solution is to connect the turbine to the reduction gear. The Author, of SEMT- Pielstick, discusses these matters, including two alternative arrangements for coupling the turbine to the reduction gear. The recovery of waste heat in power stations equipped with SEMT-Pielstick engines is then described; heat balance data are given, and it is mentioned that, by using an after-burner, heat is recovered from the exhaust gases with nearly 100% efficiency. If heat is not required, the only way to recover waste energy is to generate more electricity through a Rankine cycle; such an arrangement is briefly explained. To improve the efficiency of energy recovery, the use of organic fluids, instead of steam, has been studied in several countries. Fluorinol, used with an 18PC3 engine in a Rankine cycle plant, has given an efficiency, at the alternator terminals, of 47.2% as compared with 40.9% without extra heat recovery. At present fuel costs the extra equipment needed for this further gain in efficiency could be amortised in under seven years. Because of their complexity, such high-efficiency plants may be more suitable for power stations than for ships. The article includes a heat balance diagram and a circuit diagram of an 19PC3 engine in a Rankine cycle plant. There is also a diagram of the medium-speed power plant in the Japanese "Friendship" vessels; this plant has several economically attractive features, including an alternator that can be driven through the reduction gear or by an auxiliary engine. Order from BSRA as No. 54,148.

  • Authors:
    • Bontour, M
  • Publication Date: 1979-10

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00323268
  • Record Type: Publication
  • Source Agency: British Ship Research Association
  • Files: TRIS
  • Created Date: Feb 18 1981 12:00AM