P
Pega Hrnjak
Researcher at Urbana University
Publications - 132
Citations - 1985
Pega Hrnjak is an academic researcher from Urbana University. The author has contributed to research in topics: Pressure drop & Microchannel. The author has an hindex of 19, co-authored 122 publications receiving 1540 citations. Previous affiliations of Pega Hrnjak include University of Illinois at Urbana–Champaign & Saint Petersburg State University of Information Technologies, Mechanics and Optics.
Papers
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Journal ArticleDOI
Experimental validation of a prototype ejector designed to reduce throttling losses encountered in transcritical R744 system operation
Stefan Elbel,Pega Hrnjak +1 more
TL;DR: Experiments confirmed that like in a conventional transcritical R744 system with expansion valve, the high-side pressure control integrated into the ejector could be used to maximize the system performance.
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Microchannel heat exchangers for charge minimization in air-cooled ammonia condensers and chillers
Pega Hrnjak,Andy D. Litch +1 more
TL;DR: In this article, the authors presented a prototype ammonia chiller with an air-cooled condenser and a plate evaporator, which reduced the charge to 20g/kW (2.5oz/Ton).
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Experimental and numerical study on microchannel and round-tube condensers in a R410A residential air-conditioning system
Chang Yong Park,Pega Hrnjak +1 more
TL;DR: In this paper, the effect of different type of condensers on the performance of R410A residential air-conditioning systems was investigated, and the results showed a reduction of charge and pressure drop in the microchannel condenser.
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Characteristics of two-phase flow pattern transitions and pressure drop of five refrigerants in horizontal circular small tubes
TL;DR: Wang et al. as mentioned in this paper investigated the characteristics of two-phase flow pattern transitions and pressure drop in horizontal small stainless steel tubes of 0.5, 1.5 and 3.0 inner diameters.
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Experimental investigation on two-phase flow boiling heat transfer of five refrigerants in horizontal small tubes of 0.5, 1.5 and 3.0 mm inner diameters
TL;DR: An experimental investigation on two-phase flow boiling heat transfer with refrigerants of R-22, R134a, R-410A, C3H8 and CO2 in horizontal circular small tubes is presented in this article.