Naslov
Two-phase heat transfer during refrigerant evaporation in a solar collector tube

Autori
Soldo, Vladimir ; Grozdek, Marino ; Ćurko, Tonko

Vrsta, podvrsta i kategorija rada
Radovi u zbornicima skupova, cjeloviti rad (in extenso), znanstveni

Izvornik
61st ATI National Congress &#8211 ; International Session &#8220 ; Solar Heating and Cooling&#8221 ; (Conference Proceedings) / University of Perugia - Perugia : Morlakija, 2006, 207-212

Skup
61st ATI National Congress &#8211 ; International Session &#8220 ; Solar Heating and Cooling&#8221 ;

Mjesto i datum
Perugia, Italija, 14.09.2006

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Heat transfer; evaporation; solar collector

Sažetak
The paper presents the calculation of heat transfer in a tube of the solar collector (evaporator) where the refrigerant R134a evaporates. The test system used consists of a compressor, a freon-water compact plate condenser, an electronic expansion valve and two parallel unglazed solar collectors. The solar-assisted heat pump with direct expansion of the refrigerant in the solar collector uses the solar irradiation and the ambient temperature as a heat source on the evaporator. The heat transfer in the two-phase flow of the refrigerant in a horizontal tube is expressed by the expressions taken over from the VDI Wärmeatlas. The effect of the mass velocity G (kg/(m2 s)), the heat flux based on the inner surface of the tube q (W/m2) and the vapour quality x on the heat transfer coefficient in the heat pump solar collector is recorded. Results of calculation have shown that the nucleate boiling is dominant in the first part of the evaporator-collector, while in the second part of the evaporator, with the increase in vapour quality, the convective evaporation prevails.

Izvorni jezik
Engleski

Znanstvena područja
Strojarstvo

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