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Energy and Exergy Analyses of HVAC systems
Hakan Caliskan,Hiki Hong 대한설비공학회 2017 대한설비공학회 학술발표대회논문집 Vol.2017 No.6
In this study, evaporative air cooling systems are taken into account as HVAC systems. The direct, indirect and novel Maisotsenko cycle evaporative air cooling systems are explained and the first and second laws of thermodynamics analyses of the evaporative air cooling systems are illustrated. A case study of Maisotsenko cycle based air cooling system is studied under energetic and exergetic perspective. The wet bulb effectiveness, cooling capacity and energetic coefficient of performance (COP) of the system are found in the energy analysis. On the other hand, the exergy input rates of dry air and water, exergy output rate, exergy loss rate, exergy destruction rate, useful output exergy rate, exergetic COP (COPex), exergy efficiency of the system are determined in the exergy analysis. It is found that the energetic COP of the system is very high as 8.43, while the exergetic COP (COPex) rate is low as 0.08. Furthermore, the second law of thermodynamic (exergy) efficiency of the system is determined to be 25%.
Goksen Cecen,Hakan Salci,Deniz Seyrek Intas,Nureddin Celimli,Gulsum Ulke Caliskan 대한수의학회 2015 Journal of Veterinary Science Vol.16 No.1
This study aimed to compare thickness of the capsule, corium, and soft tissues measured ultrasonographically and macroscopically in selectedregions of bovine claws. A hundred and twenty claws (n = 120) of 15 healthy Holstein bovines were obtained. After cleaning the claws,ultrasonographic measurement of the capsule, corium, and soft tissues was performed while submerging the claws in a water bath. Macroscopicmeasurements were taken after cutting of the claws axially. These values were compared statistically. According to the macroscopicmeasurements, the mean thickness ± standard deviation (SD) of the capsule for dorsal wall and sole was 6.2 ± 0.1 and 9.5 ± 0.4 mm, respectively. The thickness of the corium and soft tissues for dorsal wall and sole was 4.5 ± 0.1 and 5.3 ± 0.1 mm, respectively. Ultrasonographically, themean thickness ± SD of the capsule for dorsal wall and sole was 4.7 ± 0.1 and 7.8 ± 0.3 mm, respectively. The thickness of the corium andsoft tissues for dorsal wall and sole was 4.3 ± 0.1 and 5.9 ± 0.2 mm, respectively. Findings demonstrated that ultrasonography can be reliablyto measure of the thickness of the hoof capsule, corium, and soft tissue in bovine claw.
Hongjie Piao,Hakan Caliskan,JAE DONG CHUNG,Jong Hyun Kim,Hiki Hong 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.10
Since Korean apartments are high-rise structures, the only renewable energy that can be applied for ZEB advantage is in fact solar energy. The CO 2 reduction effect of PVT, which can produce heat and electricity at the same time, has already been noted, and is 2.1 times greater than that of PV alone. Like the solar thermal system, the PVT requires a differential temperature controller (mode 1), which can increase the price. In the present work, the new methods, mode 2 and mode 3, that eliminates the costly differential temperature controller was proposed and the experiment was conducted. While electricity is generated from PV, mode 2 operating the circulation pump with this electricity, has some heat loss during weak solar radiation. Mode 3, which supplemented mode 2, showed equivalent performance compared to the existing method, mode 1. The simulation results for these Modes were consistent with the experimental results to within 5 %, and from this, the validity of the existing simulation research results was verified. The annual simulation showed a CO 2 reduction effect of about 158 kg_CO 2 /m 2 year regardless of the method.
Cuneyt Uysal,Hasan Ozcan,Hakan Caliskan,Ho-Young Kwak,Huseyin Kurt,Hiki Hong 대한설비공학회 2017 대한설비공학회 학술발표대회논문집 Vol.2017 No.6
An Organic Rankine Cycle is theoretically modelled and thermoeconomically investigated for different evaporator effectiveness. In thermoeconomic analysis, the Specific Exergy Costing (SPECO) method is used and the effect of evaporator effectiveness on unit exergy cost of electricity generated by the system is investigated. Exergy value of electricity generated by the system increases with increase in evaporator effectiveness. On the other hand, increase in evaporator effectiveness causes to an increase in hourly capital cost of system components and overall system. The results showed that the unit exergy cost of electricity generated by the system is 36.72 $/kJ for evaporator effectiveness of ε =0.5, while it is 41.64 $/kJ for ε =0.95.