Optimization of CHP Dryer Heat Exchanger Performance Using CFD

This study aimed to optimize the performance of a heat exchanger to utilize the wasted energy from an internal combustion engine (ICG) for powering an online dryer. Nearly 30% of the input energy in an ICG is wasted in the engine exhaust, presenting an opportunity to convert this wasted energy into useful electrical energy. Heat exchangers can achieve this by converting the engine's output energy into the energy required by an online dryer. The researchers used computational fluid dynamics (CFD), the firstlaw of thermodynamics, and response surface methodology (RSM) to optimize the heat exchanger's performance. They studied variables such as the exchanger’s length, number of baffles, fluid flow velocity, and number of tubes. The experiments were based on the Box-Behnken design of experiments for 24 trial runs. Simulations were conducted using ANSYS Fluent 15, and the results were used for thermodynamic evaluation. The ANOVA results revealed that the linear components (distance betweenbaffles, number of tubes, number of tubes × number of baffles, and the square power of the inlet fluid velocity) had the greatest effect on performance. Increasing the number of baffles (up to 63) and the inlet air velocity (up to 2m/s) improved performance, but further increases negatively impacted it. The study identified two optimal conditions: maintaining selected variable ranges resulted in 37.55% efficiency, while maximizing inlet velocity and minimizing exchanger length achieved 65.52% efficienc .

Optimization of CHP Dryer Heat Exchanger Performance Using CFD Keywords:

Thermodynamic analysis , Computational fluid dynamics , Temperature , Optimization , Fluid velocity