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Završni rad predstavlja proračun indirektnog rashladnog procesa u mljekarskoj industriji u svrhu hlađenja 1000 L mlijeka u jednom satu s 15 o C na 4 o C, u hladnjaku pomoću vodene otopine soli (rasoline). Rasolina se u isparivaču hladi s 0 o C na -3 o C. Proces se vrši u području zasićenja, a rashladna tvar je amonijak. Dakle, toplinska energija mlijeka preko posrednika (rasoline) predaje se rashladnoj tvari – amonijaku koji na račun primljene topline mijenja svoje agregatno stanje (iz kapljevitog prelazi u plinovito). Cilj ovog rada je ispitati karakteristike parnog kompresijskog rashladnog uređaja s amonijakom kao rashladnom tvari, te dimenzionirati kondenzator za ukapljivanje zasićenih para NH 3 . Rezultati proračuna ukazuju da se za kondenzaciju 42,66 kg/h amonijaka može uzeti vodoravni višecijevni kondenzator sljedećih karakteristika: u cijevnom snopu ima 30 cijevi vanjskog promjera d o = 19,05 mm, 16 BWG. Raspored cijevi je u trokutu s korakom od 25,4 mm. Duljina cijevi je 2,44 m, unutarnji promjer plašta 0,2032 m s dvije pregrade koje imaju odsječak 25%. Kondenzator je tipa cijevni snop u plaštu s dva prolaza rashladne vode kroz cijevni snop i jedan prolaz amonijaka kroz plašt. : The final paper presents the calculation of the indirect cooling process in the dairy industry for the pur- pose of cooling 1000 L of milk from 15 o C to 4 o C in an hour, using an aqueous salt solution (saline). Saline is cooled from 0 o C to 3 o C in an evaporator. The process takes place in the saturation area, and ammonia is used as the refrigerant. Thereby the heat energy of milk is transferred to the refrigerant – ammonia – through the mediator – saline: due to the heat received, ammonia changes its aggregate state (from liquid to gaseous). The aim of this study has been to examine the characteristics of the shell and tube condenser with ammonia as the refrigerant, and to dimension the condenser for the condensation of saturated NH 3 vapours. The calculation results indicate that a horizontal multi-tube condenser of the following properties can be used for the condensation of 42.66 kg/h ammonia: a tube bundle with 30 tubes of the outer diameter d o = 19.05 mm, 16 BWG. The tube arrangement is triangular with a tube pitch of 25.4 mm. The tube length is 2.44 m, the shell inside diameter is 0.2032 m with two 25% segmental baffles. The condenser is of the tube bundle type in the shell with 1 shell pass (ammonia) and 2 tube passes (cooling water). |
