This research presents an essential oil (EO) distillation method with improved efficiency, called recurrent water and steam distillation (RWASD), as well as the testing of a 500 L prototype essential oil distillation machine (500 L PDM). The raw material used was 100 kg of lime fruit. At each distillation time point, the test result was compared with that obtained via water and steam distillation (WASD), and different raw material grid configurations were taken into consideration. It was found that distillation using the RWASD method increased the amount of EO obtained from limes by 53.69 ± 2.68% (or 43.21 ± 2.16 mL) compared with WASD. The results of gas chromatography mass spectrometry (GC-MS) analysis of bioactive compounds from the distilled EO revealed that important compounds were present in amounts close to the standards reported in many studies; namely, β-myrcene (2.72%), limonene (20.72%), α-phellandrene (1.27%), and terpinen-4-ol (3.04%). In addition, it was found that the temperature, state of saturated steam, and heat distribution during distillation were relatively constant. The results showed the design, construction, and heat loss error values of the 500 L PDM were 5.90 ± 0.29% and 7.83 ± 0.39%, respectively, leading to the use and percentage of useful heat energy to stabilize at 29,880 ± 1,494 kJ/s and 22.47 ± 1.12%, respectively. Additionally, the shape of the grid containing the raw material affects the temperature distribution and the amount of EO distilled, with values 10.14 ± 0.51% and 8.07 ± 0.40% higher for the normal grid (NS), respectively, as well as an exergy efficiency of 49.97 ± 2.49%. The highest values found for exergy in, exergy out, and exergy loss were 294.29 ± 14.71 kJ/s, 144.76 ± 7.23 kJ/s, and 150.22 ± 7.51 kJ/s, respectively. The obtained results can be further developed and expanded to promote the application of this method in SMEs, serving as basic information for the development of the EO distillation industry.

This research explored different types of two-phase flow patterns that influenced heat transfer rate by assessing rectangular two-phase closed thermosyphon (RTPCT) made from glass with the sides of equal length of 25.2 mm, aspect ratio 5 and 20, evaporation temperature of 50, 70, and 90 °C, working substance addition rate of 50% by volume of evaporator, and water inlet temperature at condensation of 20 °C. Upon testing with aspect ratios 5, three flow patterns emerged which were: bubble flow, slug flow and churn flow respectively. As per the aspect ratio 20, four flow patterns were discovered which were: bubble flow, slug flow, churn flow and annular flow, respectively. Aspect ratio 5 pertains characteristic which resulted in a shorter evaporation rate of the RTPCT than that of the aspect ratio 20, thus, a shorter flow distance from the evaporator section to heat releaser was observed. Therefore, flow patterns at aspect ratio 5 exhibited a faster flow velocity than that of the aspect ratio 20. Furthermore, changes of flow pattern to the one that is important for heat transfer rate can be easily achieved. Churn flow was the most important type of the flow for heat transfer, followed by slug flow. Moreover, with aspect ratio 20, annular flow was the most important flow for the heat transfer, followed by churn flow, respectively. Throughout the test, average heat flux as obtained from the aspect ratio 5 were 1.51 and 0.74 kW/m2 which were higher than those of the aspect ratio 20. The highest heat flux at the operating temperature of the evaporator section was 90 °C, which was equivalent to 2.60 and 1.52 kW/m2, respectively.

This research investigated effects of parameters on heat transfer characteristics of a rectangular cross section heat pipe with mesh wick (RHP/MW). The working substance used Distilled Water and Refrigerant R-11. Heat loads at the evaporator were set at 20, 40, 60 and 80 W. Results revealed that, throughout the test, RHP/MW/ R-11 gave the highest heat transfer rate and average heat flux of 26.91 W and 2054.57 kW/m2 respectively. Heat Load of 80 W produced the lowest total thermal resistance of 0.4388 °C/W with the highest average thermal efficiency of 52.91%, the highest efficiency among the test cases. This is due to an increase of heat receiving areas of RHP/MW. More heat is transferred through the pipe wall to the wet perimeter of the working substance which caused the working substances in the evaporator to boil faster. The mesh wick also helped the condensed working substance to disperse around the inner tube wall and resulted in a thin film of the condensate liquid. This resulted in a higher heat transfer rate and heat flux for the RHP/MW. Mesh wick also generated capillary pressure that drew the condensed liquid back to the evaporator. The maximum capillary pressure obtained from the test was 93.29 N/m2 when the heat load of 80 W was applied to the RHP/MW/R-11. RHP/MW/R11 greatly enhances the heat transfer characteristics. Thus, it is suitable for application as an alternative to specific work sites that require smooth contact with heat receiving areas.