Impact of twisting tapes with various pitch lengths on the exergy and entropy performances of line heaters
- PDF / 3,745,862 Bytes
- 13 Pages / 595.276 x 790.866 pts Page_size
- 110 Downloads / 140 Views
(2020) 42:485
TECHNICAL PAPER
Impact of twisting tapes with various pitch lengths on the exergy and entropy performances of line heaters Ali Sulaiman Alsagri1 Received: 3 April 2020 / Accepted: 28 July 2020 © The Brazilian Society of Mechanical Sciences and Engineering 2020
Abstract Water bath fire tube heaters, so-called line heaters, are commonly used for industrial applications from small scales to large scales. The main problem of such heaters is the very low effectiveness of the heater due to the inefficient heat transfer within the heater (mainly between the fire tube and gas flow). The effects of using a specific type of twisting tape on the performance of these heaters, a typical heater used in natural gas pressure reductions points, were recently investigated. This study assesses the impacts of twisting tapes with different styles placed in the gas coil of the heater on the entropy generation and exergy performance of these heaters via computational fluid dynamic methods. For this, a typical gas mixture and typical line heater were considered. The results show that twisting tapes with larger numbers of twists and shorter twist pitch better enhance the exergy efficiency of the heater and decrease the rate of entropy generation over the gas heating process. Based on the obtained results, twisting tapes with the 17 and 68 twists decrease the rate of entropy generation by 16.8% and 27.1% and decrease the Bejan number for, respectively, over 36% and 77%. Keywords Line heater · Twisting tapes · Exergy analysis · Entropy generation rate · Bejan number
1 Introduction Heat transfer enhancement is possible via active and passive methods or a mix of these two approaches [1]. Active methods are those techniques that require external power or source to improve the rate of heat transfer, e.g., using vibrating surface, spray, etc. [2]. Passive methods, on the other hands, are not based on any external forces rather just based on the use of an insert, a twisting tape, nanoparticles, etc., to increase the overall heat transfer coefficient via picking up the surface area, the turbulence level or the conductivity of the interacting fluids, and so forth [3]. Although passive techniques might have stronger effects, the need for an external actuator adds to the initial cost of the system as well as its operation and maintenance costs Technical Editor: Jader Barbosa Jr. This article has been selected for a Topical Issue of this journal on Nanoparticles and Passive-Enhancement Methods in Energy. * Ali Sulaiman Alsagri [email protected] 1
Department of Mechanical Engineering, College of Engineering, Qassim University, Unaizah, Saudi Arabia
[4]. Thus, deciding about the use of an active solution is a matter of how vital and how cost-efficient the heat transfer enhancement process is [5]. On the other hand, passive techniques are, in most cases, much cost-efficient and easy to implement. Among all the possible passive techniques, adding nanoparticles to the heat exchanging fluid, increasing the surface area using fins o
Data Loading...
