An Economical Evaluation of the Water/Steam Injection in a CHP Microturbine Cycle

In this paper we study the economical evaluation of injecting the water/steam into the micro gas turbine (MT) cycle witch operate in combined heat and powercycle. Heat and electricity cogeneration is a way for optimizing energy consumption. Cogeneration power plants produce both electric and thermal from one energy source. These systems could work by different movers but one of the most important and applied prime movers are Microturbine. Microturbines are small electricity generators which their producted electric power is 25-350 kW and their efficiency is almost 18 % that can reach to 30 % approximately by use of recuperator in their cycle. By water/steam injection into the MT cycle, the power will be enhanced and its efficiency will be changed too. The fundamental aim of this study is economic evaluation of outfit the MT cycle to water/steam injection system. Here after the presentation of cogeneration systems, there are explanations of Microturbines and a thermodynamic analysis has been shown. Then the experimental and simulation results of water and steam injection to the different points in the cycle were compared. At last the economic evaluation of these cases and the energy production cost of any system were evaluated by Matlab codes. However injection increase the produced power, but according to the energy and set prices, the injection to the system is not economical. Non-injected system have the least payback (6 year) and its energy production cost is 0.043 $/kWh. But between the injection cases, water injection into the combustor is preferable choic