The performance of MWCNT + Fe₃O₄/water hybrid nanofluids as the coolant of a plate heat exchanger is experimentally investigated for particle concentrations in the range from 0.05 to 0.3 vol % and for coolant flow rate from 3 to 7 lit/min. The hybrid MWCNT + Fe₃O₄ nanoparticles were prepared by the chemical precipitation method and characterized with XRD, SEM, Raman, and VSM techniques. The thermal conductivity, viscosity, density and specific heat of MWCNT + Fe₃O₄ hybrid nanofluid was measured experimentally and compared with the literature values. The results show that the exergy efficiency of the hybrid nanofluid is 10.5% higher than that of de-ionized water at flow rate of 7 lit/min and particles concentration of 0.3 vol %. Thermal performance factor is found to be greater than 1 for the hybrid nanofluids (0.05–0.3 vol %), with its maximal value of 1.12 occurs at 0.3 vol % and flow rate of 7 lit/min. The effectiveness of 0.3 vol % nanofluid is higher than the de-ionized water by 11.65% at the flow rate of 3 lit/min and by 13.21% at 7 lit/min. The number of transfer units of 0.3 vol % hybrid nanofluid is higher than that of de-ionized water by 20.88% and 24.29% at flow rates of 3 and 7 lit/min, respectively. A tradeoff between the first and operating costs suggest that operating at a coolant flow rate of 5 lpm will yield the lowest cost. Therefore, benefits of reducing the size and enhancing heat transfer of the PHE via the use of MWCNT + Fe₃O₄/water hybrid nanofluid outweigh the additional power requirement.

MWCNT + Fe ₃ O ₄ /水杂化纳米流体作为板式换热器冷却剂的性能通过实验研究，颗粒浓度范围为 0.05 至 0.3 vol%，冷却剂流速为 3 至 7 升/分钟。杂化MWCNT + Fe ₃ O ₄纳米粒子通过化学沉淀法制备，并用XRD、SEM、拉曼和VSM 技术表征。MWCNT + Fe ₃ O ₄的热导率、粘度、密度和比热通过实验测量混合纳米流体并与文献值进行比较。结果表明，在流速为 7 升/分钟和颗粒浓度为 0.3 vol% 的情况下，混合纳米流体的火用效率比去离子水的火用效率高 10.5%。发现混合纳米流体（0.05-0.3 vol %）的热性能因子大于 1，其最大值 1.12 出现在 0.3 vol % 和 7 升/分钟的流速下。0.3 vol% 纳米流体的效率在 3 升/分钟的流速下比去离子水高 11.65%，在 7 升/分钟的流速下高 13.21%。在 3 和 7 升/分钟的流速下，0.3 vol% 混合纳米流体的转移单元数比去离子水的转移单元数分别高 20.88% 和 24.29%。第一成本和运行成本之间的权衡表明，以 5 lpm 的冷却剂流量运行将产生最低的成本。因此，通过使用 MWCNT + Fe 来减小 PHE 的尺寸和增强传热的好处₃ O ₄ /水混合纳米流体超过了额外的功率需求。