Assessment of improvement potential of a condensed combi boiler via advanced exergy analysis

Abstract

The combi boilers are commonly used for the heating purposes in residences since the natural gas has started to be used prevalently as fuel. Depending on this common usage, the investigations on the development of these kinds of boilers accelerated in the last decades. In this aim, it is very important to determine the improvement limits from the thermodynamic point of view. In this study, a 24 kW commercial condensed combi boiler was experimentally performed under the real operating conditions to determine the improvement paths from the thermodynamics point of view. In this aim, the advanced exergy analysis was conducted to determine the improvement potential of the combi boiler by defining ideal and unavoidable conditions including the combustion process. The most improvable components were determined as the combustion unit and recuperator. In the combustion unit, it was determined that the gas radiation has a considerable rate with 40.16% in the heat transfer phenomena for the real operating conditions. As conclusion, an improvement potential of approximately 14.32% and 7.09% was determined for the combustion unit and recuperator, respectively. The overall improvement potential of the combi boiler system was determined as 22.17%.