I researched the master’s thesis at the Engineering Technical College – Kirkuk, presented by the student Fatima Awni Taher. (Evaluating the performance of a double-tube heat exchanger using nanofluids through an internal convoluted tube)
The study addressed:
Performance evaluation of a heat exchanger with a twisted inner tube of length m (1) The outer tube is made of PVC with a diameter of mm (40.6) and the diameter of the twisted inner tube (mm (11). is made of copper using water once and nanofluid again and compare the results.
The thesis aimed to:
Conduct an experimental and numerical study to improve the effectiveness of the double-tube, counter-flow heat exchanger. Aluminum oxide particles with a diameter of 20 nm were used at a volumetric concentration of 0.1% for the practical aspect. The cold fluid flows into the inner tube of both exchangers (smooth and twisted) at a volumetric flow rate of (3, 4, 5) lit/min, which enters the exchanger at a temperature of (18˚C) ±1, while hot water flows in the space between the two tubes at a constant volumetric flow rate. (3) lit/min and enters the heat exchanger at a temperature of (63˚C) ±1. As for the theoretical aspect, the study was completed by taking new concentrations of the aluminum oxide nanofluid (0.3, 0.5)% in addition to the concentration of (0.1)% using the program (ANSYS Fluent 2023 R1).
The researcher found that:
The practical results showed that as the Reynolds number increases and using aluminum oxide with water, the Nusselt number increases compared to water, as an increase of (54)% was obtained at a concentration of (0.1)%. Numerically, the percentage of increase was (60.7, 60.9, 63)% for concentrations (0.1). , 0.3, and 0.5)%, respectively. The results also showed that the friction coefficient of aluminum oxide increases with increasing volumetric concentrations and decreases with increasing Reynolds number. As for the total heat transfer coefficient, the experimental and numerical results showed an increase in the total heat transfer coefficient with increasing volumetric concentrations of nanoparticles, as the increase was (5, 6, 7)% for concentrations (0.1, 0.3, 0.5)%, respectively, as well as for the heat transfer rate, as the results showed that the heat transfer rate increases with increasing particle size concentrations and with increasing Reynolds number, as the increase was (5, 6.2, 7.3)%. For concentrations (0.1, 0.3, 0.5)%, respectively, the results showed that the effectiveness of the exchanger increases with an increase in the volumetric flow rate and with an increase in the volumetric concentration of nanoparticles. As for the criterion for evaluating the thermal performance of the nanofluid, the results showed that it increases with an increase in the volumetric concentration of nanoparticles in the basic fluid The results showed good convergence between the experimental and numerical studies, and the percentage of deviation was (6.2)% when compared to temperatures.
The discussion committee consisted of the following gentlemen:
1. Professor Dr. Tahseen Ahmed Tahseen, Chairman
2. Assistant Professor Dr. Musa Mustafa Wais, member
3. Lecturer Dr. Nabil Mukhlif Abdul Razzaq, member
4. Lecturer Dr. Hussein Haider Muhammad Ali, member and supervisor