Babak Aghel

The limited resources of fossil fuels and environmental pollution have led researchers to use renewable green fuels such as biodiesel. The important costs in the biodiesel production process are heating and raw materials. To reduce these costs, in this work, by transesterification of waste cooking oil in two T-shaped and helical glass microreactors, which are located inside the boxes equipped with mirror plates, the chamber temperature reached 63 °C and led to 90 % energy savings. The operating parameters of retention time were the catalyst concentration and the oil to methanol volume ratio. XRF, XRD, FTIR, and SEM tests were used to determine the elemental and morphological characteristics of KOH and CaO catalysts. This transesterification via methanol using the Box-Behnken method was designed which capable of producing biodiesel with a purity of 99.97 %. Under optimal conditions of 300 sec for CaO, a catalyst dose of 10 %, and the oil to methanol volume ratio 2 the purity was 99.97 % and for KOH at 420 sec, a catalyst dose of 3 %, and the oil to methanol volume ratio 2 the purity was 98.99 %. The performance of the two microreactors was evaluated under optimal conditions; the performance of the helical type was better due to its geometric structure and greater T-shape mixing. The results show that the use of the glass microreactor assisted by solar heat can significantly reduce the operating cost by increasing the mixing, shortening the residence time, and maintaining the reaction temperature in the range of 50–63 °C, resulting in a 90 % reduction in energy consumption.