Thermodynamic evaluation and working fluid selection for a heat pump integrated into a hydropower plant HVAC system : a case study from Serbia

Rudonja, Nedžad (author), Zlatanović, Ivan (author), Banjac, Miloš (author), Gojak, Milan (author), Todorović, Ružica (author)

This paper presents a thermodynamic analysis of two types of heat pumps integrated into the heating, ventilation, and air conditioning (HVAC) system of the “Bajina Bašta” hydropower plant located in Serbia. The study aims to replace existing electric boilers with more energy-efficient solutions by utilising renewable heat sources. A comparative evaluation of water source heat pump (WSHP) and air source heat pump (ASHP) configurations was conducted using a custom-developed MATLAB model based on CoolProp data of working fluids. The analysis was supported by real data obtained through in situ measurements of air and water temperatures at the selected location, ensuring accurate input parameters for the simulations. Five refrigerants (R-410A, R-407C, R-134a, R-32, and R-1270) were used, and R-32 was selected as the optimal working fluid because of its high efficiency, moderate flammability, and low environmental impact. The lowest coefficient of performance (COP) for the WSHP was 3.27 in January, while the seasonal coefficient of performance (SCOP) reached 3.36, approximately 15.5 % higher than the ASHP counterpart (SCOP = 2.91). The study confirms that, upon analyzing the entire heating period, WSHP systems are technically and environmentally superior to ASHPs in the locations studied. The proposed configuration, based on real measured data and obtained results, can significantly improve energy efficiency and reduce internal electricity consumption in hydropower plants, thereby supporting the decarbonisation of large-scale renewable energy facilities. While most previous studies have focused on improving energy efficiency in buildings, this work demonstrates the substantial yet underexplored potential for efficiency improvements in the electricity production sector in Serbia. The study specifically examines hydropower plants in Serbia, where heating and air conditioning systems built in the 1960s remain highly energy inefficient. By quantifying the benefits of integrating WSHP and ASHP systems, the research highlights a pathway toward significantly enhancing the energy efficiency of hydropower infrastructures.

• Language: English
• Keywords: hydropower plant, heat pump, energy efficiency, COP, SCOP
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2025
• Number of pages: 7 str.
• Numbering: Vol. 71, no. 7/8
• PID: 20.500.12556/RUL-175281
• UDC: 621
• ISSN on article: 2536-3948
• DOI: 10.5545/sv-jme.2025.1344
• COBISS.SI-ID: 254406915
• Publication date in RUL: 23.10.2025

Record is a part of a journal

• Title: Strojniški vestnik
• Shortened title: Stroj. vestn.
• Publisher: Fakulteta za strojništvo
• ISSN: 2536-3948
• COBISS.SI-ID: 294943232

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Title: Celovita ocena zmogljivosti zobniških prenosov vetrnih turbin z drsnimi ležaji

Abstract

V članku je predstavljena termodinamična analiza dveh tipov toplotnih črpalk, integriranih v sistem ogrevanja, prezračevanja in klimatizacije (HVAC) hidroelektrarne Bajina Bašta v Srbiji. Cilj raziskave je zamenjati obstoječe električne kotle z energetsko učinkovitejšimi rešitvami z izkoriščanjem obnovljivih virov toplote. Opravljena je bila primerjalna ocena vodne toplotne črpalke (WSHP) in zračne toplotne črpalke (ASHP) z uporabo po meri razvitih MATLAB modelov, ki temeljijo na podatkih knjižnice CoolProp o delovnih fluidih. Analizo so podprli realni podatki, pridobljeni z in- situ meritvami temperatur zraka in vode na izbrani lokaciji, kar je omogočilo natančne vhodne parametre simulacij. Uporabljenih je bilo pet hladiv (R-410A, R-407C, R-134a, R-32 in R-1270), pri čemer je bil kot optimalno hladivo izbran R-32 zaradi visoke učinkovitosti, zmerne gorljivosti in nizkega vpliva na okolje. Najnižje grelno število (COP) za WSHP je znašalo 3,27 v januarju, medtem ko je sezonsko grelno število (SCOP) doseglo 3,36, kar je približno 15,5 % več kot pri ASHP (SCOP = 2,91). Raziskava potrjuje, da so WSHP-sistemi ob upoštevanju celotnega ogrevalnega obdobja tehnično in okoljsko superiorni v primerjavi z ASHP v analiziranih lokacijah. Predlagana konfiguracija, ki temelji na dejanskih meritvah in dobljenih rezultatih, lahko pomembno izboljša energetsko učinkovitost ter zmanjša notranjo porabo električne energije v hidroelektrarnah, s čimer podpira razogljičenje velikih obnovljivih energetskih objektov. Medtem ko so se prejšnje raziskave večinoma osredotočale na izboljšanje energetske učinkovitosti stavb, ta študija izpostavlja pomemben, a premalo raziskan potencial izboljšanja učinkovitosti v sektorju proizvodnje električne energije v Srbiji. Posebej obravnava hidroelektrarne v Srbiji, kjer so sistemi ogrevanja in klimatizacije, zgrajeni v šestdesetih letih, še vedno izrazito energetsko neučinkoviti. S kvantifikacijo koristi integracije WSHP in ASHP sistemov raziskava ponuja smer za pomembno povečanje energetske učinkovitosti hidroenergetskih objektov.

• Keywords: hidroelektrarna, toplotna črpalka, energetska učinkovitost