WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article Citation - WoS: 2Citation - Scopus: 2Sleep Quality: Design of Bedroom Ventilation and Evaluation Within the Scope of Current Standards(Elsevier Science Sa, 2025) Cobanoglu, Nur; Karadeniz, Ziya Haktan; Sofuoglu, Sait Cemil; Toksoy, MacitIndoor air pollution is one of the leading environmental risks to public health considering people now spending nearly 90 % of their day in indoor environments. A significant portion of this time indoors is devoted to sleeping, making it crucial to address the impact of indoor environmental conditions on sleep quality. International ventilation standards such as ASHRAE and CEN, as well as country-specific guidelines, offer valuable recommendations for ventilation design in residential buildings, including bedrooms. This study aims to evaluate the importance of determining ventilation rates in sleeping spaces using Indoor Air Quality Procedure (IAQP) compared to Ventilation Rate Procedure (VRP) in accordance with current standards. Here, the IAQP approach for determining air flow rate is based on the CO2 balance by maintaining CO2 levels in any sleeping environment below specified upper limits of 750 ppm and 1000 ppm. This study focused on the adult population, which forms the majority of society, with analyses conducted for both single and double occupancy sleeping conditions. The volume of environment where ventilation is not required during sleep (Vf) is inaccessible in conventional sleeping environments (10-21.6 m3 per person). Therefore, proper ventilation is of great importance for any sleeping space that is smaller than the Vf. The results of the analyses show that for the conventional sleeping volumes, CO2 levels reach 750 ppm (upper limit for comfortable sleep) in the first hour and increase to the disturbed sleep zone in about 2 h. Additionally, a chart outlining the necessary ventilation flow rates is suggested for maintaining maximum CO2 concentrations of 750 and 1000 ppm during different sleep durations and in various sleeping environments with varying volumes. Finally, the ventilation rates determined based on unit area and/or occupancy levels in standards (referred to as VRP) may not always be adequate or may be excessive in order to maintain CO2 concentrations below the recommended limits of 750 and 1000 ppm. It is advised to utilize demand-controlled ventilation by considering the system design as recommended by IAQP.Article Citation - WoS: 12Citation - Scopus: 15Assessment and Improvement of Indoor Environmental Quality in a Primary School(Taylor and Francis Ltd., 2017) Ekren, Orhan; Karadeniz, Ziya Haktan; Atmaca, İbrahim; Ugranlı Çiçek, Tuğba; Sofuoğlu, Sait Cemil; Toksoy, MacitThis study reports levels of indoor environmental quality variables before and after installation of heat recovery ventilation in a primary school located in an urban area in Izmir, Turkey. A CO2-based modeling was performed to determine the required flow rates that would comply with an international ventilation standard, followed by computational fluid dynamics modeling for best airflow distribution in a classroom. Temperature, CO2, PM2.5, and total volatile organic compounds were found at undesired levels, among which relative humidity, CO2, and PM2.5 were improved after the intervention. Reductions in the mean and maximum concentrations were 29% and 68% for CO2 and 29% and 46% for PM2.5. This intervention study was a part of the city-wide main project that aimed to increase awareness of the students and their families, teachers, and staff regarding importance of indoor environmental quality in both at school and home due to its possible effects on children's health and academic performance, one of the major challenges of today's societies all around the globe.Article Citation - WoS: 66Citation - Scopus: 79Piping Network Design of Geothermal District Heating Systems: Case Study for a University Campus(Elsevier Ltd., 2010) Yıldırım, Nurdan; Toksoy, Macit; Gökçen, GüldenGeothermal district heating system design consists of two parts: heating system and piping network design. District heating system design and a case study for a university campus is given in Yildirim et al. [1] in detail. In this study, piping network design optimisation is evaluated based on heat centre location depending upon the cost and common design parameters of piping networks which are pipe materials, target pressure loss (TPL) per unit length of pipes and installation type. Then a case study for the same campus is presented. © 2010 Elsevier Ltd.Article Citation - WoS: 39Citation - Scopus: 41Economic Assessment of Geothermal District Heating Systems: a Case Study of Balçova-Narlıdere, Turkey(Elsevier Ltd., 2006) Erdoğmuş, Berkan; Toksoy, Macit; Özerdem, Barış; Aksoy, NiyaziGeothermal energy is an important renewable energy resource in Turkey. The aim of this research is to evaluate the Balcova-Narlidere geothermal district heating system from an economic perspective. The system is the largest one in Turkey in terms of heating capacity and located in Izmir. Although there are some assessments regarding energy and exergy analysis for the Balcova-Narlidere geothermal district heating system, an economic assessment was not performed, previously. The profitability of the investment is investigated by using internal rate of return method. Seven hundred and eighty different scenarios are developed in this assessment. In order to estimate the potential cash flows in the remaining project life, operating cost in 2002 is decreased and increased, alternatively, between 5% and 30% by 5% in each step, while monthly energy utilization price is changed between US$ 17 and 72 in those scenarios. The energy utilization prices are suggested according to zero IRR value for all scenarios due to the consideration of social and environmental concerns in this investment. It is found that, the proper monthly energy utilization price for a 100 m2 household would be US$ 55.5 when the operating cost and heating capacity in 2002 were remained constant.Article Citation - WoS: 25Citation - Scopus: 32District Heating System Design for a University Campus(Elsevier Ltd., 2006) Yıldırım, Nurdan; Toksoy, Macit; Gökçen Akkurt, Güldenİzmir Institute of Technology campus is in use since 2000 and still under development. At present, heating is provided by individual fuel boilers. On the other hand, the campus has a geothermal resource in its borders with a temperature of 33 °C. Because of this low geothermal fluid temperature; heat pump district heating system is considered for the campus. As an alternative, fuel boiler district heating system is studied. Each heating system is simulated using hourly outdoor temperature data. For the simulations, a control system with constant flow rate and variable return water temperature is used and the main control parameter is the indoor temperature. Various heating regime alternatives have been studied for heat pump district heating system for the various condenser outlet temperature and geothermal fluid flow rate, and two of these alternatives are given in this study. Furthermore, economic analysis has also been done for each heating system alternative based on investment and operational costs. Results indicate that heat pump district heating system has the highest investment but lowest operational cost. The alternatives are evaluated according to internal rate of return method, which shows the profit of the investment and resulted that, the heat pump district heating system has minimum 3.02% profit comparing with the fuel boiler district heating system at the end of the 20-year period.Article Testing Corrosion Rates on Steel Piping in Geothermal District Heating(National Association of Corrosion Engineers, 2008) İnce, Umut; Toksoy, Macit; Güden, MustafaThe corrosion behavior of St-37 pipeline carbon steel (CS) in a geothermal district heating system was tested at two different fluid velocities. An experimental set-up, directly connected the the end of the transmission line of a geothermal well, was used to assess the corrosion of St-37 steel tensile test coupons prepared in accordance with ASTM E8 in geothermal fluid. The geothermal fluid entered the set-up with a relatively low velocity, 0.02 m/s, and then injected into the well with a relatively high fluid velocity, 9.6 m/s. It was observed that while the uniform corrosion rates were relatively low, pitting corrosion rate, mainly driven by the sulfate-reducing bacteria (SRB) activity, was relatively high and more pronounced at low fluid velocities. St-37 steel material is prone to the pitting type corrosion, thus a biocide chemical addition and the fluid velocity of 2 to 3 m/s in transmission line were recommended to reduce SRB activity to reduce the pitting corrosion rate.