Akademik Veri Yönetim Sistemi
JOURNAL OF THE FACULTY OF ENGINEERING AND ARCHITECTURE OF GAZI UNIVERSITY, cilt.38, sa.4, ss.2521-2536, 2023 (SCI-Expanded, Scopus, TRDizin)
In the study, the effects of variants such as air excess coefficient, flue gas temperature, boiler capacity and fuel consumption on the heat recovery from the flue gas have been presented in detail. The heat recovery scenarios have been presented for reusing the waste energy from the flue gas for space heating, domestic hot water, and preheating combustion air and the applicability of these scenarios has been investigated in terms of thermodynamics and economics. According to the results of the study, in the second scenario examined to cover the domestic hot water need of the guest house building, the energy savings of the scenario can be provided during 20 years of economic life is $122,820.83, and it has the highest savings income among the scenarios. In addition, it is possible to recover approximately 50% of the flue gas loss with thanks to the scenario (Figure A). On the other hand, the third scenario of heating the boiler combustion air with waste heat is the easiest and most economical scenario because its payback period is only one year, and there are no extra excavation and pipe costs. Figure A. Changes in temperatures of flue gas, water and outer wall of pipe depending on pipe length Purpose: In the study, we have purposed heat recovery of waste flue gas from boilers of Kafkas University district heating system. The designs of heat recovery units are investigated in terms of thermodynamics and economics for applications such as space heating, domestic hot water and preheating combustion air thanks to the recovered heat. Theory and Methods: The measurements such as flue gas temperature, air excess coefficient, and flue gas velocity were taken by TESTO flue gas analyzer and integrated pitot tube. Condensing economizer in the heat recovery unit is designed using Colburn and Hougen method and the one-dimensional finite difference method. The equivalent annual cost method is utilized for the economic analysis of the heat recovery units. Results: The waste heat loss of flue gases from boilers of Kafkas University district heating system has been calculated between 6-8% according to the combustion analysis and annual cost of this heat loss has been found as $58,658.79. Thanks to the condensing economizer with a heat transfer area of 6.53 m2, the flue gas outlet temperature can be reduced to 40 degrees C and 50% of the flue gas loss can be recovered. Conclusion: There are high heat losses in district heating systems, and by determining the locations and qualities of these heat losses, the design and application of appropriate heat recovery systems can large extent contribute to the country's economy by reducing heat losses.