Naslov
Application of Carbon Dioxide in a Transcritical Refrigeration Cycle

Autori
Hrastović, Dario ; Soldo, Vladimir ; Grozdek, Marino

Izvornik
Strojarstvo (0562-1887) 49 (2007), 2; 161-168

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
carbon-dioxide; natural refrigerants; transcritical heat pumps

Sažetak
During the last century, the refrigeration industry was forced to change refrigerant technology due to commitments to the Montreal protocol. The industry is redesigning technology towards the application of new environment friendly refrigerants that may be used for a longer period. Refrigerants should be chlorine free, which means that they do not have impact on the ozone layer, and at the same time they should have low global warming potential. Emphasis in this paper is given to the use of carbon-dioxide R744 and ammonia R717 because of their low impact on the atmosphere. The cascade system technology is known with CO2 as the refrigerant in the first stage and NH3 as the refrigerant in the second stage of the cascade. This paper elaborates the use of CO2 in the transcritical area, i.e. above the critical point where there is no vapour condensation. The paper deals also with problems connected with high working pressure of CO2, thermodynamic properties and design of transcritical heat pumps and their components. Compared to other refrigerants, CO2 has one specific property: low critical temperature 31, 1 °C at 73, 8 bar. The operating pressure for gas cooling will be extremely high, above 100 bar. In the subcritical area the enthalpy change is influenced by the temperature change, while in transcritical area enthalpy change is affected by pressure. In the transcritical area, the coefficient of performance may be controlled by the refrigerant pressure after compression.

Izvorni jezik
Engleski

Znanstvena područja
Strojarstvo

Napomena
Rad je na engleskom jeziku prezentiran kao predavanje na skupu 19th International Symposium and Exhibition of Heating, Refrigerating and Air Conditioning : Interklima ’ 07, održanom od 19.-20.04.2007., Zagreb, Hrvatska ; u cjelosti objavljen u Zbornik radova Interklima 2007 ; Andrassy, Mladen (ur.). - Zagreb : Fakultet strojarstva i brodogradnje Sveučilišta u Zagrebu, 2007. str. 68-78 ; ISBN: 978-953-6759-37-8.

POVEZANOST RADA