2 sonuçlar
Arama Sonuçları
Listeleniyor 1 - 2 / 2
Öğe Comparison of CLTD and TETD cooling load calculation methods for different building envelopes(Mugla Sitki Kocman University, 2020-06-30) Oktay, Hasan; Yumrutaş, Recep; Işık, Mehmet ZerrakkiThe estimation of the cooling load through the building envelope is an essential task in the selection of proper HVAC system components that influences the building’s performance. For this task, ASHRAE has presented several methods to calculate the building cooling load due to heat gain, such as the total equivalent temperature difference method (TETD), the cooling load temperature difference method (CLTD), and the radiant time series method (RTS). The present study aims to explore the accuracies of those calculation methods in terms of energy efficiency. In this regard, an analytical solution method utilizing Complex Finite Fourier Transform Technique (CFFT) was developed for the calculation of cooling load due to heat gain to compare the temperature differences obtained from the TETD and CLTD methods. Then, a computer program was prepared in MATLAB to perform the calculations based on an analytical methodology. Besides, the estimated CLTD and TETD values by the CFFT were compared with those values presented in the Handbook of the ASHRAE. The calculation results revealed there is a good agreement between the analytical and presented results in the ASHRAE Manual for the selected building envelopes. However, several differences were found between the estimated TETD and CLTD cooling load values and those presented in the Handbook of ASHRAEÖğe Combustion, performance, and emissions of safflower biodiesel with dimethyl ether addition in a power generator diesel engine(Taylor & Francis, 2020-04-29) Aydın, Hüseyin; Işık, Mehmet Zerrakki; İşcan, Bahattin; Topkaya, HüsnaIn this study, the effect of dimethyl ether (DME) addition to diesel (ultralow sulfur diesel fuel) and biodiesel fuels on the combustion, performance, and emissions of a diesel-powered generator was investigated. For this purpose, fuel samples of the ternary blend that volumetrically composed of 10% safflower biodiesel–10% dimethyl ether–80% ultralow sulfur diesel fuel (B10DME10), the ternary blend that volumetrically composed of 25% safflower biodiesel–25% dimethyl ether–50% ultralow sulfur diesel fuel (B25DME25), the binary blend that volumetrically composed of 25% safflower biodiesel–75% ultralow sulfur diesel fuel (B10DME10) B25, and pure safflower oil biodiesel (B100) and standard ultralow sulfur diesel (D2) were prepared. The test engine was loaded by power drawing from the generator by the usage of equivalent powered electrical heating resistances. Generally, using DME with biodiesel improved the combustion properties of biodiesel blends that can be attributed to the lower viscosity of DME. The maximum cylinder pressure was obtained for B10DME10 in general and sometimes for B25DME25. When test fuels are compared, DME blends showed higher and earlier peaks of heat release compared to diesel and biodiesel blend fuels especially. It was found that combustion is more efficient from mass fuel consumption (MFC) and brake specific fuel consumption (BSFC) values in the use of DME than biodiesel. BSEC values of using DME in the blends considerably decreased that it is the proof of improved combustion and energy efficiency. The highest average efficiency values were obtained for B25DME25 as 28.3% although it has a lower calorific value than D2 due to the considerably improved combustion properties of DME, while the average efficiency values were 23.1%, 23.3%, and 20.7% for D2, B25, and B100 fuels, respectively. Highest carbon monoxide (CO) emissions were obtained in the use of pure biodiesel, while the lowest CO emissions were obtained in the use of DME. The addition of DME is seen to increase the nitrogen oxides (NOx) and CO emissions.
