Heat transfer enhancement of double pipe heat exchanger using rotating of variable eccentricity inner pipe

Abstract

The double pipe heat exchanger type has low heat transfer rate compared with other types of heat exchangers. Therefore, this article aims to enhance the heat transfer rate of that type of heat exchanger by introducing a rotation of the heat exchanger inner pipe combined with changing the pipes eccentricity. Three dimensional, steady sate and incompressible CFD model was constructed for investigation of the effect of rotation and eccentricity on the heat transfer rate. A double pipe heat exchanger which was used for this study consists of an inner pipe and an outer pipe of diameter 50 mm and 150 mm respectively with a length of 2000 mm. The inner pipe is assumed to rotate at a variable speed of 0, 100, 200, 300, 400 and 500 rpm and the eccentricity of the inner pipe is changed from 0.0 to 40 mm from the center of the outer pipe. Verification and validation for the numerical simulation are presented. The results showed a significant enhancement by 223% in the heat transfer rate due to the eccentricity change up to 40 mm and at the inner pipe rotation of 500 rpm. However, the pressure penalty through the heat exchanger increase by 53% in the rotational speed of inner pipe up to 500 rpm and eccentricity of 40 mm and it is accepted penalties.