Thermodynamic analysis of a tunnel biscuit oven and heat recovery system

Biscuit baking ovens are produced as tunnel type to reduce the cost of final product and increase the production capacity. Tunnel type ovens are designed in the form of conveyor and wire mesh or steel belt is used as a carrier element according to the biscuit type. In tunnel type biscuit ovens, the product that enters as dough from one end of the tunnel comes out as a baked product from the other end of the tunnel. In this study 1.2 m belt width and 61.5 m long tunnel oven which has 1850 kg/h Petit Beurre biscuit production capacity is analyzed. Working parameters of this tunnel oven taken into account for calculations. Natural gas is used to generate heat for baking and during baking high amount of energy released to the atmosphere with exhaust gas and water evaporated from biscuit dough. In this study, the energy and exergy analysis of the system made by taking into account the properties of flue gas discharged from industrial type biscuit oven. Flue gas released from chimney to the atmosphere is 503.15 K which could be used to generate electricity with Organic Rankine Cycle. The data obtained as a result of this study can be used to optimize the energy required to produce unit product. As a result of energy and exergy analysis of the system, 58.62 kW of power could be generated by Organic Rankine Cycle by using waste flue gas. It has been observed that energy efficiency of the oven increased from 3.90% to 11.04% and exergy efficiency of the oven increased from 0.5% to 6.22% by generating electricity with Organic Rankine Cycle.