Exergy analysis of building hot water heating systems

In this thesis, energy and exergy analyses of a Public Building with a net covered area of 23,675 m2 located in Bursa was carried out. Within the scope of the analyses, heat loss calculations, exergy losses and fancoil irreversibility of spaces in the building were calculated. In addition, the irreversibility of the natural gas fired hot water boiler used in the building was calculated as 941 kW. The exergy efficiency of the boiler was determined as % 21.15. According to heating regime design of the building, exergy losses and fancoil irreversibilities of all spaces in the building were calculated. In the study, flow rate, air velocity and temperature components were measured and the relationship between entropy production number and heat transfer efficiency was also investigated. As a result of the calculations produced from the obtained measurement data, entropy production number (N_s )=0.01213 and heat transfer efficiency(ε)=0.64 were determined. The values were compared with the results of theoretical calculations according to three different temperature regimes (90-70˚C, 80-60˚C and 70-50˚C). In addition, the analysis of the relationship between the number of entropy production and heat transfer efficiency with the current study data, error analysis was applied, the error analysis of entropy production number (N_s ) and the error rate of heat transfer efficiency calculations were determined. When the results were evaluated, it was determined that the second highest law efficiency for the boiler in the hot water heating system was in the 90-70 ˚C regime and the most suitable working regime for the fancoil was the 70-50 ˚C regime, where the generation of entropy was minimal.