Thesis (M.Sc.) - Cairo University - Faculty of Engineering - Department of Mechanical Power Engineering

In the present study, Double pipe heat exchanger inserted with wavy tape turbulator is analysed numerically by solving the governing equations using ANSYS FLUENT 15.0 software. The thermal performance of the unit in the turbulent flow regime for Reynolds number range of 5000 {u2013} 25,000 is studied for different wavy tape geometries. Firstly, five different wavy tape angles of 45o, 60o, 90o, 120o and 150o are considered. Results showed that adding wavy tape increases the heat transfer rate up to 193% compared to plain tube coupled with a large value of the friction factor. It is seen that small wavy tape angles produce higher heat transfer enhancement and pressure drop. Also, wavy tape amplitude is investigated and the results showed that increasing wavy tape amplitude increases the heat transfer rate and also the pressure drop. Eventually, it is concluded that the ideal tape amplitude is about 54% of the pipe inner diameter. Finally, parametric model is developed in order to investigate the effect of the variation of different parameters on the performance of heat exchanging unit. Variations of inlet flow velocity of hot and cold streams are employed monitoring other performance parameters response. Results showed that variation of inlet velocity affects heat transfer rate and outlet temperatures of both streams. Also, effectiveness of heat exchanger is affected. Moreover, fouling of heat transfer surface is taken into consideration showing that fouling layer affects the response of performance parameters to velocity variations

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