Analytical analysis of a renewable fuel operated recuperated gas turbine
Being famous for their high power density, low emission, compact size, and low maintenance gas turbines are excellent choice for the power and aircraft industry. Over the years, the increasing energy demand has caused a lot of environmental pollution problems. Fossil fuels pose a lot of threats to our environment when it comes to their extraction, transportation and utilization. In order to ensure a healthy environment in the near future, we must focus extensively on designing and manufacturing devices with higher efficiency to minimize the damage done to the environment. Therefore, using renewable fuels such as biofuels and many others can be helpful in reducing emission levels.
This paper will introduce a single shaft Capstone type micro gas turbine operating with different fuels. The generated power and pollutant emission levels will be investigated for every fuel used by the gas turbine. Gas turbines in general can cope very well with both liquid and gaseous fuels, without having any large differences regarding to their useful power. The used gaseous fuels are natural gas and methane, while the liquid fuels are biodiesel and bioethanol. However, bioethanol will be mixed with water, and the bioethanol-water solution will be investigated twice, firstly in gaseous form, and secondly in liquid form. The hot flue gases from the turbine will be directed to an inner heat exchanger to reduce the required input heat. The inner heat exchanger will increase the Capstone's gas turbine efficiency. However, the inner heat exchanger will result in a slight pressure drop.
When using bioethanol-water solution, the adiabatic flame temperature changes as the water content in the fuel mixture changes. The temperatures through the gas turbine depend strongly on the water content. Thus, an iterative process is needed to calculate the proper temperatures, hence the useful power and efficiency of the gas turbine. This iteration method can be used for any liquid fuel diluted with water. Using pure bioethanol (as pure as possible) is more efficient, but the price of bioethanol-water solution is cheaper and results in lower emission levels. Hence, financial analysis will be carried out to show the most optimum percentage of bioethanol to water ratio.