Improvement of thermal comfort and efficient energy use in buildings based on active-passive systems for overheating reduction : doctoral dissertation

Zavrl, Eva (author), Stritih, Uroš (mentor), Dovjak, Mateja (comentor)

As a consequence of global warming, the enery demand for cooling is increasing. A novel active-passive system (APS) with phase change material (PCM) integrated into the substructure of the internal walls and ceiling for cooling is introduced. To ensure sufficient cooling effect of the system during the daytime cycle, the system must solidify completely during the nighttime cycle. To improve the heat transfer of the PCM, a ventilated air gap was placed behind PCM wall and ceiling substructure for free cooling. APS was investigated and designed based on literature review, unstacionary full-scale numerical simulation (building level), experimental investigation, parametric study performed with micro-scale numerical model in CFD and calculation of energy performance and operation cost. First type of scenarios experimentally tested the cooling effect of the PCM during the daytime cycle, determined by the temperature difference between the cell-without and cellPCM. Second type of scenarios experimentally and numerically tested the PCM solidification time during the nighttime cycle. APS decreased the indoor temperatures for by 4.5 °C. The results showed that with the current configuration, the PCM can be sufficiently solidified at inlet temperature of 17 °C. APS system has lower operating costs than G class AC device.

• Language: English
• Keywords: dissertations, phase change material, overheating reduction, thermal energy storage, indoor thermal comfort, cooling of buildings, ventilated air gap
• Work type: Doctoral dissertation
• Typology: 2.08 - Doctoral Dissertation
• Organization: FS - Faculty of Mechanical Engineering; FGG - Faculty of Civil and Geodetic Engineering
• Place of publishing: Ljubljana
• Publisher: [E. Zavrl]
• Year: 2023
• Number of pages: XXVIII, 198 str.
• PID: 20.500.12556/RUL-152401-1d4238b9-f42a-4670-da6e-41481f1e9e73
• UDC: 697.1:628.8:620.9(043.3)
• COBISS.SI-ID: 173886467
• Publication date in RUL: 23.11.2023

Secondary language

• Language: Slovenian
• Title: Izboljšanje toplotnega ugodja in učinkovite rabe energije v stavbah na podlagi uvajanja aktivno-pasivnih sistemov za zmanjšanje pregrevanja : doktorska disertacija

Abstract

Zaradi globalnega segrevanja se povečuje potreba po energiji za hlajenje stavb. Raziskan je bil aktivno-pasivni sistem (APS) s fazno spremenljivimi snovmi (PCM) integriranimi v podkonstrukcijo notranje stene in stropa za hlajenje stavb. Za zagotavljanje zadostnega hladilnega učinka sistema v dnevnem ciklu, se mora PCM v nočnem ciklu popolnoma strditi. Za izboljšanje prenosa toplote v PCM ponoči je bila za stensko in stropno podkonstrukcijo PCM nameščena prezračevana zračna rega namnjena hlajenju PCM z nekondicioniranim zrakom. APS je bil raziskan in zasnovan na podlagi sistematičnega pregleda literature, nestacionarne numerične simulacije na nivoju stavbe, eksperimentalne raziskave, parametrične analize izvedene z numeričnim modelom na mikro-skali z računalniško analizo dinamike tekočin ter izračuna energetske učinkovitosti in obratovalnih stroškov APS. V sklopu prvega tipa scenarijev je bil eksperimentalno raziskan hladilni učinek PCM v dnevnem ciklu. Slednji je bil določen s temperaturno razliko med celico brez in celico s PCM. Z drugim tipom scenarijev je bil eksperimentano in numerično ugotavljan čas strjevanja PCM v nočnem ciklu. Z aplikacijo APS se je notranja temperaturo zraka znižala do 4,5 °C. Rezultati so pokazali, da se lahko PCM v APS strdi z vstopno temperaturo 17 °C. Sistem APS ima nižje obratovalne stroške kot klimatska naprava razreda G.

• Keywords: disertacije, fazno spremenljive snovi, reševanje pregrevanja, zalogovniki toplote, toplotno ugodje v prostoru, hlajenje stavb, prezračevana rega