Chapter 8-INTRODUCTION TO THERMODYNAMICS 



WORK OUT; THERMAL 



ENERGY OF STEAM 



CONVERTED TO MECHANICAL 



ENERGY IN TURBINES 



CONDENSATE 

 PUMP 



THERMAL ENERGY OF 



AUXILIARY STEAM 



CONVERTED TO 



MECHANICAL ENERGY 



:FEEDmT6ipipspiiipp?S^i^ 



THERMAL ENERGY OF 

 AUXILIARY EXHAUST STEAM 

 USED HERE TO HEAT AND 

 DEAERATE FEED WATER 



38.2 

 Figure 8-18.— Energy relationships in the basic propulsion cycle of conventional steam-driven ship. 



propulsion cycle of a conventional steam-driven 

 ship with geared turbine drive and shows some 

 of the major energy transformations that take 

 place. 



The first energy transformation occurs when 

 fuel oil is burned in the boiler furnace. By the 

 process of combustion, the chemical energy 

 stored in the fuel oil is transformed into thermal 

 energy. Thermal energy flows from the hot com- 

 bustion gases to the water in the boiler. While 

 the boiler stop valves are still closed, steam 

 begins to form in the boiler; the volume of the 

 steam remains constant but the pressure and 

 temper atuire increase, indicating a storage of 

 internal energy. When operating pressure is 

 reached and the steam stop valves are opened, 



the high pressure of the steam causes it to flow 

 to the turbines. The pressure of the steam thus 

 provides the potential for doing work; the actual 

 conversion of heat to work takes place in the 

 turbines. The changes in internal energy be- 

 tween the boiler and the condenser (as evidenced 

 by changes in pressure and temperature) indicate 

 tliat heat has been converted to work in the tur- 

 bines. The work output of the turbines turns the 

 shaft and so drives the ship. 



Two main energy transformations are in- 

 volved in converting thermal energy to work in 

 the turbines. First, the thermal energy of the 

 steam is transformed into mechanical kinetic 

 energy as the steam flows through one or more 

 nozzles. And second, the mechanical kinetic 



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