Analysis of heat pipe capability in pyrolysis reactor liquid collection system through limitation graph approach

Abstract Developing alternative energy sources is crucial today. One underutilized biomass source is palm kernel shells. Pyrolysis, the oxygen-free decomposition of biomass, yields three products: bio-char, bio-oil, and bio-gas. In a pyrolysis reactor, a Liquid Collection System (LCS) converts vapor into liquid smoke. Heat pipes, efficient heat exchangers, have several limitations, including capillary, viscous, sonic, entrainment, and boiling limits, which can be illustrated in a heat pipe limitation graph. This research used an LCS equipped with 24 heat pipes to study its effectiveness and optimize the heat pipe design using a limitation graph approach. The study found that the viscous limit and boiling limit are the primary operational constraints of the heat pipe system. The optimum heat pipe temperature was achieved at the boiling limit at 70°C, with a total output of 1,143.44 Watts. With 24 pipes, the LCS could only convert 36.45% of the total gas mass. Optimization involved varying the heat pipe’s length, diameter, wick pore size, and inclination angle. Through limitation graph calculations, it was determined that design optimization can be achieved by reducing the total heat pipe length to 350 mm, avoiding wick pore sizes above 70 µm, increasing the inner diameter, and modifying the heat pipe’s inclination orientation.