Browsing by Author "Kilkis, Birol I."

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    An Exergetic Approach to The Age of Universe
    (2014) Kilkis, Birol I.; https://orcid.org/0000-0003-2580-3910; AAJ-2321-2020
    Recent finding by Bond et al. (2013) about the age of the star HD 140283 (14.46 +/- 0.8 Gyr) requires us to reconsider the estimates about the age of the universe, namely 13.817 +/- 0.048 Gyr. Their conflicting result is analytically supported by the paper in Int. J. Exergy by Kilkis (2004). This paper, which introduced the Radiating Universe Model (RUM) with exergy flow to an infinitely-sized thermal bath at 0 K, predicted that the age of the universe is 14.885 +/- 0.040 Gyr. It further calculated that Hubble constant is 65.7 km s(-1) Mpc(-1) and the expansion of the universe has been accelerating since the cosmic age of 4.4 Gyr due to a positive, time dependent cosmological number that is slightly decreasing and presently it is 8.8 x 10(-36) s(-2). The exergy flow rate, solved by the lumped-capacitance method, changes with the square of cosmic time and is currently 1.224 x 10(50) erg.s(-1).
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    An Exergy-Based Algorithm for Optimizing CHP Systems in Health Facilities
    (2014) Kilkis, Birol I.
    Health facilities have diverse thermal and electrical loads with challenging profiles and non-coincident peaks. This paper lays the basic optimization algorithm, with two objectives, namely minimizing CO2 emissions and reducing the pay-back period of the investment. The algorithm is based on the Rational Exergy Management Model and searches the optimum CHP capacity with the objective of maximum exergy efficiency. The algorithm also factors in the negative effect of tree cutting on CO2 sequestration potential, which often occurs in the construction of very large new hospitals. Four building scenarios were analyzed, one which is a business as usual type of health facility building and the fourth one is a near net-zero energy and exergy building. Results show that the optimization search may substantially increase the exergy efficiency, fuel savings, and reduce CO2 emission by up to 50%.