Abstract
The main objective of this work is to compare different configurations of helical baffles in the cold fluid side of a double tube heat exchanger. For this analysis double pipe heat exchangers are divided into three different domains such as two fluid domains hot fluid in the inner tube and cold fluid in the outer pipe and a solid domain as helical baffles on inner tube of hot fluid. The hot water flows inside the heat exchanger tube, while the cold fluid flows in the outer side in the direction of counter flow. Mass flow rate cold fluid was varied from 0.1 kg/s to 0.3 kg/s while the flow rate in the inner tube i.e. hot water was kept constant at 0.1 kg/s. the inlet temperature of hot fluid taken as 40oC while Cold fluid inlet temperature taken as 15oC. The fluent software is used to calculate the fluid flow and heat transfer in the computational domains. The governing equations are iteratively solved by the finite volume formulation with the SIMPLE algorithm. Results show that that the maximum temperature drop of 10.9 oC for hot fluid and the maximum temperature rise of 11.9 oC for cold fluid are observed at 0.3 kg/sec mass flow rate for double pipe heat exchanger with double helical baffles. It has been also observed that the heat transfer coefficient increasing with the increasing in the mass flow rate of cold fluid. The overall heat transfer coefficients differ significantly by 20.4 % at same mass flow rate, because the considerable difference between heat transfer surface area on the inner and outer side of the tube resulting in a prominent thermal enhancement of the cold fluid.
Highlights
A heat exchanger is a device that is used to transfer thermal energy between two or more fluids, between a solid surface and a fluid, or between solid particulates and a fluid, at different temperatures and in thermal contact
In the present work a three dimensional CAD model of double tube heat exchanger is created with the help of design modular of ANSYS workbench
After performing computational fluid dynamics analysis of double pipe heat exchanger at different mass flow rate of hot and cold fluid varied from 0.1 kg/s to 0.3 kg/s while the inlet temperature of hot and cold fluid are 40oC, and 15oC respectively
Summary
Qianmei Fu at el. [1] In this study, the effects of structure ratio of the heat exchanger and the entrance velocity of SCO2 on heat transfer and flow resistance are investigated numerically. The results show that the velocity of S-CO2 plays a major role in a small flow channel determining the overall performance. It concludes that reducing the flow resistance and improve the performance of heat transfer needs to be considered first in the optimal design of a double-pipe heat exchanger using S-CO2 as working fluid. Rate, or to predict the outlet temperatures of the hot and cold fluid streams in a specified heat exchanger. Heat exchangers usually operate for long periods of time with no change in their operating conditions. They can be modeled as steadyflow devices. The fluid streams experience little or no change in their velocities and elevations, and the kinetic and potential energy changes are negligible
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