Efficiency amplified: Enhancing energy performance in biodiesel vacuum thermal water removal system

Abstract

Thermal vacuum is a common method for removing water from biodiesel, where water content is one of the biggest challenges in the implementation of biodiesel as a fuel. This process has been confirmed through performance testing in this study and has successfully reduced the water content of biodiesel by 65.8 %. There is potential to improve the energy performance of this process by using heat exchangers. Accordingly, this study presents both experimental and economic evaluations to find the efficacy of shell-tube heat exchangers and plate heat exchangers in biodiesel vacuum thermal water removal system. The heat exchangers were designed with a capacity of 300 L/hour to facilitate the heat transfer between a 35 °C and a 105 °C fluids. This experiment included performance tests analyzed by the effectiveness-Number of Transfer Units (Ɛ-NTU) method and economic analysis. The shell-tube heat exchangers employed 189 tubes and three shells with a total heat transfer area of 18.5 m2, whereas the plate heat exchangers consisted of two U-type units with a total heat transfer area of 4.41 m2. The effectiveness and NTU provided by plate heat exchangers are 86.33 % and 6.02, while by shell-tube heat exchangers are 70.64 % and 2,81 respectively. From the economic analysis, plate heat exchangers and shell-tube heat exchangers were able to reduce annual process costs by IDR 76,818,565 and IDR 76,818,565 respectively. These findings indicate that implementing plate heat exchangers in the biodiesel vacuum thermal water removal system is more advantageous than utilizing shell-tube heat exchangers.