One dimensional simulation of a gas engine cogeneration system

Energy efficiency has become a sensitive issue in Turkey and all around the world. There is an increasing awareness about efficient usage of the energy sources amoung countries, amoung companies and amoung individual basis. Especially, efficiency of energy is an important agenda item because of the rising energy costs, security of supply and environmental pollution. Cogeneration systems become widespread during last years due to the efficiency on energy usage. Thanks to these systems there will be no extra energy consumption by using waste heat which is emitted during electricity production. In large complexes which need both electricity and heat, such as factories, hospitals, hotels, university campuses, airports and shopping malls, energy costs can be significantly reduced by cogeneration systems. In addition, reduction of fuel consumption, compliance with emissions regulations and reducing environmental pollution can be provided, too. Gas turbines, steam turbines or internal combustion engines can be used for energy production in cogeneration systems. Amount of energy demand, environmental conditions and feasibility results are the most significant factors about which type of machine should be selected for energy production. Natural gas is frequently used as a clean energy source as well as easy operation and reasonable price. Even though external dependence is a handicap, natural gas is keep its preferableness all around the world as well as in Turkey. Before a cogeneration system investment, many feasibility studies are required. One of the feasibility study steps is analyzing the output values which can be provided by input values. In other words, how the parameters such as temperature, pressure and so on affect power, efficiency and fuel consumption which play active roles in system investment decision and system profitability calculation. In this thesis, a program which simulates a gas engine cogeneration system is created. At first, cogeneration systems, usage areas and techniques are mentioned in the thesis. Thereafter specifically MWM brand gas engine cogeneration systems and cogeneration plant equipments are detailed. The working principle of the system is explained and supported by schematic shapes and pictures. The thermodynamic model which is generated for the simulation program is explained by all the equations and assumptions it contains. Thermodynamic model begins with the compression of gas air mixture and goes forward with intercooling phase, the combustion process in the gas engine combustion chambers, calculation of the power output, the exhaust output and ends with waste heat energy output. The codes of thermodynamic model is created in MATLAB software. The requested values from the user are entered in MATLAB interface. Related values are used in the thermodynamic model and the equations are solved. After end of calculations, a datasheet is created as an excel sheet and presented to the user by simulation program. This datasheet shows the output values which can be obtained from the system according to the values entered. At the end of the study, several analysis are performed in the simulation program. Output value comparisions are done for different input value conditions. These comparison cases are altitude change, different ambient temperature conditions, different gas engine type situations and different engine load cases. According to the results of this analysis, rising of altitude and rising of ambient temperature cause to power and system efficiency decrease. In addition, it is observed that TCG 2032 series of MWM brand has more efficiency than TCG 2020 and TCG 2016 series under same input conditions. For engine load cases, simulation results shows that efficiency values decrease if engine load drops.