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Organski Rankineov ciklus je varijacija Rankineovog ciklusa u kojem se kao radni medij umjesto vode koristi lakoisparljivi organski fluid. Kako su u tom slučaju za isparavanje dovoljne relativno niske temperature ovakva tehnologija omogućava iskorištavanje energije niskotemperaturnih izvora poput otpadne topline, geotermalne energije, sunčeve energije, te energije biomase. Ta toplina se pretvara u rad koji se uglavnom koristi za dobivanje električne energije. U ovom završnom radu se iznose neke najčešće upotrebe ORC-a, kriteriji koje radna tvar mora zadovoljavati, ukratko je opisano nekoliko tvari koji su našli svoju praktičnu primjenu uz jednostavni proračun iskoristivosti procesa za dana radne uvjete. Organic Rankine cycle is a variation of Rankine cycle where organic fluid with low evaporation temperature is used instead of water. Thus, enabling the use of low-temperature energy source, this sort of technology makes it possible to yield useful energy from low-temperature heat source like waste heat recovery, geothermal energy, solar energy and biomass. The heat is converted to work which is the most likely used for generating the electricity. In this final thesis are stated some of the most common application of ORC technology, criteria that each organic fluid must meet, some of the most commonly used compounds, as well as the simple calculation of their efficiency under stated working conditions.

Cijene goriva nezaustavljivo rastu, a ekološki problemi vezano za izgaranje fosilnih goriva postaju alarmantni. S druge strane, čak i najefikasniji stroj današnjice, sporohodni dizelski motor, 50% energije sadržane u gorivu otpušta u atmosferu u obliku topline sadržane u ispušnim plinovima i rashladnoj vodi. Cilj ovog rada je istražiti kogeneracijsko (CHP) postrojenje koje bi ovu izgubljenu energiju niske temperature, vratilo u energetsko postrojenje tankera za prijevoz nafte od 166.700/153.100 tDW (Suezmax size) za sve potrebe grijanja i proizvodnju električne energije tijekom plovidbe. Analizom mogućih rješenja odabrano je CHP postrojenje. Odabrana su i dva radna fluida te termodinamički procesi. Za potrebe istraživanja izrađuje se matematički model i promatraju se opterećenja glavnog motora od 50% do 100% SMCR. Analiza rezultata proračuna, pokazala je da parno turbinsko postrojenje u proizvodnji rada/električne energije za potrebe broda ne daje značajnije uštede čak ni kod proizvodnje 620 kWe. Drugo razmatrano CHP postrojenje s R245fa radnim fluidom u nadkritičnom Rankine- ovom ciklusu, potpuno pokriva sve potrebe za električnom energijom i toplinom uz manju količinu izgaranja dodatnog goriva. Fuel prices are going up, and ecological problems due to fossil fuel combustion are becoming alarming. On the other hand, even the most efficient contemporary machines  slow-speed diesel engines release into atmosphere 50% of energy from the fuel, in the form of heat included in exhaust gases and cooling water. The goal of this work is to research a cogeneration plant (CHP) which would utilize this waste low-temperature energy in the oil tanker 166 700/153 100 tDW (Suezmax size) power plant for all heating and electricity requirements during the ship sail. After analyses of different configurations, the CHP Plant was selected with two working fluids and the corresponding thermodynamic processes. A mathematical model was created and applied in analysis of the plant performance for the main engine load of 50% to 100% SMCR. An analysis of obtained results showed that the steam turbine plant did not result in significant fuel savings, even at power output of 620 kWe. On the other side, a CHP plant with R245fa fluid using supercritical Rankine cycle entirely covered all demands for electrical energy and heat, burning a small quantity of additional fuel only.