A second law analysis for turbulent convective flow through panel type radiator equipped with vortex generators
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A second law analysis for turbulent convective flow through panel type radiator equipped with vortex generators Meysam Hemmat1 · Faramarz Hormozi1 Received: 29 June 2020 / Accepted: 22 September 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract An irreversibility analysis is arranged for the turbulent convective flow through the panel type radiator equipped with the vortex generators. Delta wing vortex generators are installed inside the system to disrupt the flow and enhance the heat transfer rate. However, vortex generator may affect the second law efficiency of the system, which should be investigated. The increase in the entropy production restricts the thermodynamic advantages of the vortex generators. The influences of several parameters, including the attack angle of vortex generator β, space between the back edge of vortex generator and hot surface of the panel, d, and Re number, Re, on the velocity and temperature characteristics, entropy production owing to viscous friction and heat transfer, and Be number are studied. The results attained by the present numerical investigation are validated with the data reported in the literature to ensure about the accuracy of the numerical solver. The outcomes revealed that the entropy production owing to viscous friction is increased with increasing the attack angel of vortex generators and space between the back edge of vortex generator and the hot surface of the panel. The larger values of entropy production owing to heat transfer are produced when the vortex generators are placed farther from the hot surface of the panel. Both entropy production owing to viscous friction and heat transfer increase with placing the vortex generators inside the panel. The substrate of high Be number grows along the panel length and occupies most of the panel at the exit section. By the way, the entropy production owing to viscous friction is dominate term at the entrance of the panel owing to the high velocity gradient of the developing flow regions. Keywords Panel type radiator · Second law analysis · Vortex generator · Turbulent convective flow · Entropy production owing to viscous friction and heat transfer · Be number
Introduction Panel heat exchangers are employed in electric power transformers and space heating systems. Generally, the thermal efficiency of these heat exchangers is low due to the small value of heat transfer coefficient in the air side [1, 2]. In the literature, there are many methods, which are used to upgrade the thermal efficiency of these devices. These methods are categorized into two groups, including active and passive techniques. In active techniques, the external power should be used to input the process, while a passive method does not need any extra energy to enhance the thermohydraulic efficiency of the system [3, 4].
* Faramarz Hormozi [email protected] 1
Faculty of Chemical, Petroleum and Gas Engineering, Semnan University, Semnan, Iran
As a passive technique, vortex generators are designed to increase the heat and mass transfe
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