An Experimental Study for Heat Transfer in Laminar Pulsating Annular Flow.

Document Type : Research Studies

Authors

1 Faculty of Engineering., El-Mansoura University., Mansoura., Egypt.

2 Higher Technological Institute., Tenth of Ramadan City., Egypt.

Abstract

Heat transfer in laminar pulsating flow is experimentally investigated. Water flow through an annulus of a tubular heat exchanger is considered. An experimental set-up equipped with a computerized data acquisition system is designed and constructed to carry out this work. The test section is a tubular heat exchanger formed by two concentric tubes. The pulsating flow of cold water in the annulus is heated by a steady flow of hot water through inner tube of the tubular heat exchanger. The experimental measurements of temperature, pressure and mass flow rate for both the hot and cold fluids are eollected by a data acquisition system, which is connected to a personal computer for further data analysis. The operating parameters considered are Reynolds number, mixing ratio between pulsating and steady flows and the change in amp < /strong>litude for pulsating flow The frequency of the pulsating flow considered is i Hz. The influence of flow pulsation in the annulus on Nusselt number and its impact on the overall heat transfer coefficient and effectiveness of a tubular heat exchanger are considered. 
The results show that, flow pulsation increases Nusselt number of laminar annular flow compared with the steady flow. Such increase in Nusselt number is slightly dependent on Reynolds number. For the considered range of Reynolds number, Re=100-1100, flow pulsation causes an increase in Nusselt number by 20% in average compared to steady laminar flow.
 

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