Yazar "Hekimoğlu, Gökhan" seçeneğine göre listele

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    Eco-friendly building materials containing micronized expanded vermiculite and phase change material for solar based thermo-regulation applications
    (Elsevier, 2021) Gencel, Osman; Sarı, Ahmet; Ustaoğlu, Abid; Hekimoğlu, Gökhan; Erdoğmuş, Ertuğrul; Yaraş, Ali; Sütçü, Mücahit; Çay, Vedat Veli
    Phase change materials (PCMs) have been widely studied to decrease energy consumption and dependency on fossil fuels that causes environmental concerns, and improve building energy efficiency. In this regard, this study aimed to fabricate structural cement based mortar with indoor thermo-regulation function utilizing form stable PCM (FSPCM). FSPCM was made of micronized expanded vermiculite (MEV) impregnated with Lauric-Myristic acid eutectic mixture (LA-MA). The facile direct impregnation method was used for the production of the FSPCM. The cement-based mortars were then manufactured by replacing the FSPCM with sand at 15%, 30% and 45 wt% ratios. The basic properties of the manufactured cement-based mortars such as physical, mechanical, thermal conductivity, thermal energy storage and thermoregulation performance were systematically investigated. With the incorporation of 45% FSPCM, thermal conductivity (0.42 W/mK), bulk density (1239 kg/m(3)) and compressive strength (56.2 MPa) decreased by 60.93%, 39.2% and 85.94%, respectively. In terms of compressive strength, all samples with FSPCM can meet the standard requirements. Differential Scanning Calorimetry (DSC) analysis revealed that the melting temperature and latent heat of FSPCM and FSPCM-included cement mortar (45 wt%) are 32.16 degrees C and 73.70 J/g and 31.96 degrees C and 18.90 J/g, respectively. The thermoregulation performance test indicated that the produced FSPCM-included cement based mortars are able to provide thermal comfort by minimizing indoor temperature fluctuations and thus saving energy by reducing heating-cooling loads in buildings.
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    Novel integration of recycled-hemihydrate phosphogypsum and ethyl palmitate in composite phase change material for building thermal regulation
    (Elsevier Ltd, 2024) Koçyiğit, Şermin; Güler, Onur; Hekimoğlu, Gökhan; Ustaoğlu, Abid; Erdoğmuş, Ertuğrul; Sarı, Ahmet; Gencel, Osman; Özbakkaloğlu, Tugay
    This study investigates the properties of novel heat storage gypsum composites composed of waste Hemihydrate phosphogypsum (HP) incorporated with Ethyl Palmitate (EP) Phase Change Material (PCM) at varying concentrations of 25 wt %, 50 wt %, and 75 wt %. The focus of the research revolves around evaluating key characteristics, including leakage properties, chemical stability, microstructural analysis, heat storage characteristics, mechanical properties, and the thermal regulation performance of these novel composites. The investigation of leakage properties aimed to find the optimum EP ratio within the composite structure without causing any potential EP leakage, and it was determined to be 25 wt %. Furthermore, thermal regulation tests are conducted to assess the heat storage and release capabilities of the composites with varying HP/EP content. The latent heat storage of the HP/EP composite was determined as 46.12 J/g, even after the 750th cycle, the value only decreased to 46.03 J/g. With the porosity filling effect of EP additive in HP, as the EP additive increased, the amount of porosity decreased, and the compressive strength values increased by almost 10 %. In hot weather conditions, the EP additive provided a cooler environment between 2 and 4 °C according to thermoregulation results. This study not only holds promise in the context of developing novel heat storage composites for applications in energy-efficient building materials, thermal energy storage systems, and related sustainable technologies but also in harnessing industrial waste byproducts. It particularly highlights the value of HP as a waste material, which has a high potential for evaluation in the production of gypsum and other building materials.
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    Thermal energy saving and physico-mechanical properties of foam concrete incorporating form-stabilized basalt powder/capric acid based composite phase change material
    (Elsevier Ltd., 2023) Koçyiğit, Fatih; Bayram, Muhammed; Hekimoğlu, Gökhan; Çay, Vedat Veli; Gencel, Osman; Ustaoğlu, Abid
    The incorporation of phase change materials (PCM) in construction materials for the purpose of thermal energy storage (TES) can prevent temperature fluctuations and enable the conservation of thermal energy in buildings. Accordingly, this study aims to create a novel, environmentally friendly foam concrete incorporating a composite PCM composed of capric acid saturated waste basalt powder. Basalt powder, a byproduct of the grinding or crushing of basalt volcanic rock, was selected as a carrier material due to its high porosity resulting from its lightweight and porous nature. This allowed for the creation of a leak-free composite PCM, which was then integrated with foam concrete made of CEM I 42.5R cement, water, quartz sand, and a foaming agent. BasaltPCM was substituted into the mixture at 50% and 100% by weight of quartz aggregate. Comprehensive evaluations were conducted on the novel foam concretes with regard to their morphological, mechanical, physical, thermal, and TES properties. The results indicate that the incorporation of basalt-PCM causes a minor reduction in the dry unit weight of the mixtures and a reduction in compressive and flexural strength. However, the leakproof basalt powder/capric acid composite displayed a phase transition behavior, melting at 28.5 ◦C with a latent heat of fusion (47.9 J/g), which retained 99.5% capacity after 500 melting-solidification cycles. The specimen with 100 wt% basalt-PCM exhibited a melting temperature and latent heat of 27.8 ◦C and 17.4 J/g, respectively. Additionally, the basalt powder/capric composite exhibited high thermal stability up to 156 ◦C, far above its normal operating temperature. The foam concretes incorporating the basalt-PCM demonstrated solar thermoregulation properties, maintaining a more stable and comfortable indoor temperature. These results suggest that the form-stable PCM-incorporating foam concretes developed in this study can be considered as environmentally friendly building materials for thermoregulation and energy conservation.