The Effectiveness of Heat Transfer From Flue Gases to Ammonia-Water Mixtures

The paper deals with the theoretical comparison of the heat transfer process from the exhaust gases of a gas turbine to pure water or to an ammonia-water mixture in the single-pressure, nonreheat, heat recovery boiler. The main difference is the variable-temperature boiling of the mixture, which improves the match of the temperature profiles in comparison to the match obtained by the use of pure water. The result is smaller loss of energy and exergy. Thermal and exergetic efficiencies are improved, which means better use of the primary heat source, i.e., the fuel of the gas turbine. At the end of the paper the usefulness of the ammonia-water mixture at higher inlet (above 500°C) and outlet (above 180°C) gas temperatures is analyzed. The main advantages of the mixture disappear under such conditions.