Thermodynamic and Thermoeconomic Comparison of Steam Ejectors and Injectors with Compressors and Pumps

Parni ejektorji in injektorji predstavljajo konstrukcijsko enostavno alternativo električnim kompresorjem in črpalkam. V zaključni nalogi smo se osredotočili na področje hladilne tehnike. S termodinamskim modelom smo preučili parni ejektor z mešanjem pri konstantnem tlaku in iterativno izračunali masno razmerje tokov pri izbranih obratovalnih pogojih. Napako rezultata smo zmanjšali z nadgradnjo modela ejektorja in z uporabo rezultatov opravili eksergijsko analizo. Delovni medij je bil R600a. S termodinamsko in termoekonomsko analizo smo ovrednotili parne ejektorje in injektorje v primerjavi s kompresorji in črpalkami. Za slednje smo izračunali celotni eksergijski izkoristek z upoštevanjem povprečnih eksergijskih izkoristkov generiranja in transporta električne energije v Sloveniji. Ugotovili smo, da so v določenih primerih parni ejektorji in injektorji termodinamsko boljši od kompresorjev in črpalk. Termoekonomski izračuni pa so pokazali, da so ejektorji in injektorji dražji v izbranih konfiguracijah hladilnih sistemov.Steam ejectors and injectors present a structurally simple alternative to electric compressors and pumps. In this degree paper we focused on the field of cooling technology. We used a thermodynamic model to investigate a constant pressure mixing ejector and iteratively calculated its entrainment ratio at selected working conditions. By modifying the ejector model, we decreased the error of the results and subsequently performed exergy analysis on the given ejector. The working fluid used was R600a. With thermodynamic and thermoeconomic analysis we evaluated steam ejectors and injectors in comparison with compressors and pumps. For latter we calculated the total exergy efficiency considering the average exergy efficiencies of generation and transportation of electricity in Slovenia. We found that in certain instances steam ejectors and injectors can exergetically outperform compressors and pumps. However, thermoeconomic calculations revealed that steam ejectors and injectors are more expensive than compressors and pumps in selected cooling systems