Cogeneration - Trigeneration Systems

One of the few techniques that best ensures the conservation of energy in thermodynamics is the simultaneous production of mechanical and thermal energy.

Cogeneration is the production of energy in both electrical and thermal forms from the same system simultaneously. While the chemical energy in the fuel is converted into electrical energy in the generator, heat that can be used in processes is obtained from the exhaust energy, engine block, and aftercooler.

The primary purpose of cogeneration is to make maximum use of fuel energy. The goal of energy utilization is defined as the ratio of the total electricity and thermal energy produced annually in a cogeneration plant to the fuel energy consumed. While this value ranges between 25–40% in plants that only produce electricity, it can reach up to 90% in cogeneration plants.

For a healthy system selection, annual (if not available, monthly or weekly) consumption values should be determined and plotted on graphs. First, the annual average electricity consumption is considered, and a capacity slightly below this consumption is selected to avoid idle capacity. The primary goal should be to determine capacity based on electricity consumption.

The hot water or steam produced together with electrical energy from cogeneration systems can be passed through a system called an “absorption chiller” to produce chilled water for cooling purposes. Systems designed in this way are called “TRIGENERATION” because they can produce electricity, heating, and cooling energy at the same time.

Absorption chiller units can also produce hot water for heating and domestic use as needed. In absorption chillers operating directly with exhaust gas, the gas inlet and outlet temperatures are 260°C and 115°C, while the cooling water (chilled water) inlet and outlet temperatures are 12°C and 7°C.