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Boafo, Fred Edmond,Kim, Jin-Hee,Kim, Jun-Tae Elsevier 2019 Energy and buildings Vol.183 No.-
<P><B>Abstract</B></P> <P>The thermal and energy performance of curtain wall façades can be improved by incorporating spandrel units in areas such as slabs/plenums to hide existing building services or areas where concealment of indoor space is required. The main objective of this study was to numerically investigate the performance of curtain wall façade with integrated vacuum insulation panel (VIP) as spandrel insulation. The main study constitutes six parts: (1) concept and derivation of governing equations, (2) model and its validation, (3) VIP integration alternatives, (4) overall thermal performance considering 2D/3D thermal bridges and internal surface temperatures, (5) building energy and vision-spandrel ratio effect, and (6) limitations and challenges. Thermal behavior of the system was characterized via 3D heat transfer simulations using Physibel TRISCO according to EN ISO 10211, while dynamic building energy analysis was carried out using EnergyPlus based on a stereotypical office building unit, in relation to the humid continental climate of Incheon, Republic of Korea. The baseline model was validated with experimental data from previous study, and a marginal discrepancy less than 4% was found between them. Further, the validated model was developed into different spandrel configurations, seeking to mitigate thermal bridges while improving insulation performance, by varying VIP integration design. Results indicated that the best VIP spandrel alternative improved thermal performance of the system by about 30%. Moreover, year-round space heating and cooling energy reductions were realized by gradually increasing the spandrel area by ratio from 0% to 80%, howbeit at the expense of electrical lighting energy. Finally, some noteworthy limitations of the study and challenges related to VIP integration into curtain wall spandrel have been duly discussed.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A hybrid curtain wall system with VIP spandrel was investigated. </LI> <LI> The VIP spandrel unit was composed of VIP integrated between glass panes. </LI> <LI> 2D/3D thermal bridges are quite significant due to frames, brackets, and bolts. </LI> <LI> Alternatives to curtail thermal bridges reduced heat loss by about 30%. </LI> <LI> Year-round heating and cooling energy reductions were realized by gradually increasing the spandrel area. </LI> </UL> </P>
Performance Characteristics of Internet Data Center Cooling System Utilizing Water Source
Nicholas Lamptey Boafo,Selorm Kwaku Anka,Jong Min Choi 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.6
Internet data centers have grown significantly in recent years as a result of the extensive use of telecommunication and internet systems, and they are already causing energy and environmental challenges. Conventional data centers are usually cooled by air-source vapor compression systems which require an uninterrupted electricity supply all year round. The energy consumption of the space cooling system has been in charge by 30-50% of the total energy delivered to a typical data center. There is rare literature on the use of dam water as a potential heat source for IDC cooling systems. This paper presents a cooling system utilizing deep dam water as a heat source. The basic performance characteristics of the system were experimentally analyzed according to operational methods with emphasis on the variation of entering water temperature. It is observed that the capacity for the two modes increases significantly as the OD EWT falls. Overall system COP in the free cooling mode increased greatly rather than it in the forced cooling mode.