Experimental and analytical investigation of vibration-induced effects on the thermal performance of triplex heat exchangers

Heat exchangers (HEXs) play a critical role in efficient thermal energy management across industrial and renewable energy systems. The performance of a heat exchanger is primarily governed by parameters such as flow rate, surface area, temperature differential, and thermal conductivity. In this study, a triplex heat exchanger was analytically and experimentally investigated under vibration-induced conditions to assess its potential for enhanced heat transfer performance. The results were compared with steady-state operation to quantify the effect of vibration intensity and flow variation. In triplex heat exchanger, three concentric tubes are used, with the hot fluid flowing through Tube 2 and the cold fluid through Tubes 1 and 3. During the experimental investigation, both the mass flow rate and vibration acceleration were varied within the ranges of 0.020 kg/s to 0.30 kg/s and steady state to 5G vibration acceleration, respectively. Furthermore, the variation in temperature was analyzed over a range of Reynolds numbers for cold tube 1 and cold tube 3, which varied from 702.689 to 1055.172 and from 477.556 to 722.163, respectively, under conditions ranging from steady state to 5G vibration acceleration. When the mass flow rate in cold Tube 1 was increased from 0.020 kg/s to 0.030 kg/s under 5G vibrational conditions, the Nusselt number increased by 38.46%, indicating a substantial enhancement in convective heat transfer performance. Moreover, an increase in acceleration from steady state to 3G substantially improved the thermal effectiveness of the heat exchanger, achieving up to 93.63% efficiency at 5G acceleration after 80 min of operation. The analytical model showed excellent agreement with experimental data, with an error range of 1–5%, validating the reliability of the approach. Overall, the findings demonstrate that controlled mechanical vibration can serve as a viable mechanism for improving the thermal efficiency of triplex heat exchangers. The results provide valuable insights for the design of next-generation compact and high-performance exchangers, particularly in renewable energy and process engineering applications.