scholarly journals Effects of Fin Arrangements on Thermal Hydraulic Performance of Supercritical Nitrogen in Printed Circuit Heat Exchanger

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 861
Author(s):  
Shan Yang ◽  
Zhongchao Zhao ◽  
Yong Zhang ◽  
Zhengchao Chen ◽  
Min Yang
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Evaluation Criteria ◽  
Hydraulic Performance ◽  
Ansys Fluent ◽  
Printed Circuit ◽  
Flow And Heat Transfer ◽  
Transverse Distance ◽  
Fluent Simulation ◽  
Staggered Arrangement

The printed circuit heat exchanger (PCHE) with discontinuous fins is a novel type of compact and highly efficient plate heat exchanger, which has superior thermal hydraulic performance. The morphology and characteristics of the flow channel greatly affect the performance of the PCHE. The discontinuous airfoil fins are used in PCHE channel design because they can affect the flow and heat transfer by increasing the heat transfer area and the disturbance in the channel. In this paper, the effects of different staggered distance (Ls) and transverse distance (Lv) of airfoil fin arrangements on the heat transfer and flow of supercritical nitrogen in the PCHE are numerically simulated using ANSYS Fluent. Simulation results and subsequent analysis show that the appropriate decrease in Ls and reduction in Lv between the two rows of fins can improve the convective heat transfer of the PCHE. A fully staggered arrangement of fins (Ls = 1.2) and an appropriate increase in the Lv can mitigate pressure drop. The comprehensive performance of different channel geometries is compared by the performance evaluation criteria (PEC) in this study. It is shown that considering flow resistance and heat transfer, the comprehensive heat transfer performance can be enhanced by properly increasing the staggered distance and the vertical distance between fins. When Ls = 1.2 mm and Lv = 1.25 mm, the PEC value of the staggered channel is the highest, which is 11.6% higher than that of the parallel channel on average.

scholarly journals Numerical Investigation on Flow and Heat Transfer Characteristics of Supercritical Liquefied Natural Gas in an Airfoil Fin Printed Circuit Heat Exchanger

2017 ◽  
Author(s):  
Zhongchao Zhao ◽  
Kai Zhao ◽  
Dandan Jia ◽  
Pengpeng Jiang ◽  
Rendong Shen
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Natural Gas ◽  
Hydraulic Performance ◽  
Liquefied Natural Gas ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Printed Circuit ◽  
Flow And Heat Transfer ◽  
Staggered Arrangement

As a new kind of highly compact and efficient micro-channel heat exchanger, printed circuit heat exchanger (PCHE) is a promising candidate satisfying the heat exchange requirements of liquefied natural gas (LNG) vaporization at low and high pressure. The effects of airfoil fin arrangement on heat transfer an flow resistance were numerically investigated using supercritical liquefied natural gas (LNG) as a working fluid. The thermal properties of supercritical LNG were tested by utilizing a REFPROF software database. Numerical simulation was performed using FLUENT. The inlet temperature of supercritical LNG was 121 K,and its pressure was 10.5MPa. The reference mass flow rate of LNG was set 1.22 g/s for the vertical pitch Lv = 1.67 mm and the staggered pitch Ls = 0 mm, with the Reynolds number of about 3750. The SST k-ω model with enhanced wall treatment was selected by comparing with the experimental data. The airfoil fin PCHE had better thermal-hydraulic performance than that of the straight channel PCHE. Moreover, the airfoil fins with staggered arrangement displayed better thermal performance than that of the fins with parallel arrangement. The thermal-hydraulic performance of airfoil fin PCHE was improved with increasing Ls and Lv. Moreover, Lv  affected on the Nusselt number and pressure drop of airfoil fin PCHE more obviously. In conclusion, a sparser staggered arrangement of fins showed a better thermal-hydraulic performance in airfoil fin PCHE.

Numerical Study on Flow and Heat Transfer Performance of Natural Gas in a Printed Circuit Heat Exchanger During Trans-Critical Liquefaction

2020 ◽  
Author(s):  
Ting Ma ◽  
Pan Zhang ◽  
Jie Lian ◽  
Hanbing Ke ◽  
Wei Wang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Natural Gas ◽  
Numerical Study ◽  
Local Pressure ◽  
Local Flow ◽  
Printed Circuit ◽  
Minimum Value ◽  
Flow And Heat Transfer

Abstract The main cryogenic heat exchanger is a core piece of equipment in the liquefaction of natural gas. The printed circuit heat exchanger is gradually becoming a primary choice for the main cryogenic heat exchanger, because it has good pressure resistance, high efficiency, and compactness. In this work, a numerical simulation is conducted to examine the local flow and heat transfer characteristics of natural gas in the printed circuit heat exchanger during trans-critical liquefaction. It is found that the heat flux density reaches a minimum value and the heat transfer is the worst when the temperature difference between the hot and cold sides is the smallest. Owing to the large variations in physical properties of trans-critical natural gas, the local pressure drop exhibits an upward parabolic shape along the flow direction, and the pressure drop reaches a minimum value near the pseudo-critical point. Finally, the friction factor and heat transfer correlations for natural gas during trans-critical liquefaction are fitted.

Flow and Heat Transfer Characteristics of a Novel Heat Exchanger

2013 ◽  
Author(s):  
Haolin Ma ◽  
Alparslan Oztekin
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Exchanger ◽  
Transient Flow ◽  
Ansys Fluent ◽  
Tube Heat Exchanger ◽  
Flow And Heat Transfer ◽  
Narrow Slot ◽  
Slot Size ◽  
Tube Type

Computational fluid dynamics and heat transfer simulations are conducted for a novel shell-tube type heat exchanger. The heat exchanger consists of tube with a narrow slot oriented in the streamwise direction. Numerical simulations are conducted for the Reynolds number of 1500. The 3D turbulent flow in the tube bank region is modeled by k-ε Reynolds stress averaging method by employing ANSYS FLUENT. 3-D transient flow and heat transfer simulations are conducted to determine the flow structure and temperature profiles in the wake of cylinders in the first row and other rows. The effects of the slot size and the orientation and the arrangement of the cylinder in different configuration will be examined. The slotted tube heat exchanger improved heat transfer by more than 27% compare to the traditional shell-tube heat exchanger without slots. Enhancement in heat transfer is even higher at higher values of Reynolds number.

scholarly journals Assessment of economic, thermal and hydraulic performances a corrugated helical heat exchanger filled with non-Newtonian nanofluid

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Muhammad Ibrahim ◽  
Ebrahem A. Algehyne ◽  
Tareq Saeed ◽  
Abdallah S. Berrouk ◽  
Yu-Ming Chu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Performance Evaluation ◽  
Heat Exchanger ◽  
Economic Analysis ◽  
Evaluation Criteria ◽  
Methyl Cellulose ◽  
Hydraulic Performance ◽  
Two Phase ◽  
Heat Transfer Efficiency ◽  
Helical Heat Exchanger

AbstractImproved heat transfer efficiency with considering economic analysis in heating systems is an interesting topic for researchers and scientists in recent years. This research investigates the heat transfer rate (HTR) and flow of non-Newtonian water-Carboxyl methyl cellulose (CMC) based Al2O3 nanofluid in a helical heat exchanger equipped with common and novel turbulators using two-phase model. The requirements for dimensions and cost reduction and also energy saving in thermal systems are the main goal of this study. According to gained results usage of corrugated channel in helical heat exchanger has a considerable influence on thermal and hydraulic performance evaluation criteria (THPEC) index of helical heat exchanger and can improve the THPEC index. Thus, Re = 5000 is obtained as an optimum value, in which the maximum THPEC value is achieved. As it is found in this paper, in case of using novel heat exchanger instead of the basic smooth system, the thermal properties (by considering Nusselt number) increases about 210%, the hydraulic performance (friction factor) reduces about 28%, performance evaluation criteria index increases about 57% and the material consumption (in case of similar THPEC) decreases about 31%. In another word, with considering economic analysis for the basic and novel system which has same efficiencies, the novel one has lower length and consequently 31% lower material.

Effect of Dimple Intrusions and Curvature Radius of Rounded Corner Triangular Duct on Fluid Flow and Heat Transfer

2019 ◽  
Vol 11 (3) ◽  
Author(s):  
Rajneesh Kumar ◽  
Sourabh Khurana ◽  
Anoop Kumar ◽  
Varun Goel
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Curvature Radius ◽  
Ansys Fluent ◽  
Thermal Boundary Conditions ◽  
Flow And Heat Transfer ◽  
Rounded Corner ◽  
Reynolds Number Increase ◽  
Transverse Distance ◽  
Flow Heat

The sharp corner significantly affects the flow through triangular duct. In the corners, flow gets stagnant, which results in poor heat transfer. Therefore, in the present study, one corner of the duct is kept rounded with variable curvature radius values (Rc). The curvature radius is selected in such a way that it varied from the minimum value (i.e., Rc = 0.33 times duct height; h) to a maximum value (i.e., Rc = 0.67h,which named as conventional duct in the work). In addition to this, the combined effect of both rounded corner and dimple-shaped intrusion has also been studied on flow of air and heat transfer and for this purpose; the relative streamwise distance (z/e) is varied from 6 to 14 with constant relative transverse distance (x/e) that is10. Steady-state, turbulent flow heat transfer under thermal boundary conditions is analyzed for Reynolds number from 5600 to 17,700. ANSYS (Fluent) 12.1 software is used to perform numerical simulations and good match has been observed between the simulated and experimental results. Due to rounded corner and dimple intrusions, velocity near the corner region has higher value in comparison to the conventional duct. The uniform temperature distribution is seen in the case of dimple intruded duct as compared to conventional and rounded corner duct (with Rc value of 0.33h). In comparison to conventional duct, the heat transfer increased about 21–25%, 13–20%, and 5–8%, for the Rc value of 0.33h, 0.49h, and 0.57h, respectively, but the combination of rounded corner and dimple-shaped intrusion augments heat transfer by 46–94%, 75–127%, 60–110%, for the z/e value of 6, 10, and 14, respectively, with the Reynolds number increase from 5600 to 17,700.

scholarly journals Numerical Study on Flow and Heat Transfer Characteristics of Trapezoidal Printed Circuit Heat Exchanger

Micromachines ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1589
Author(s):  
Yuxuan Ji ◽  
Kaixiang Xing ◽  
Kefa Cen ◽  
Mingjiang Ni ◽  
Haoran Xu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Numerical Study ◽  
Three Dimensional ◽  
Channel Structure ◽  
Complex Flow ◽  
Compact Structure ◽  
Printed Circuit ◽  
Flow And Heat Transfer

Printed circuit heat exchanger (PCHE) is a promising regenerative device in the sCO2 power cycle, with the advantages of a large specific surface area and compact structure. Its tiny and complex flow channel structure brings enhanced heat transfer performance, while increasing pressure drop losses. It is, thus, important to balance heat transfer and flow resistance performances with the consideration of sCO2 as the working agent. Herein, three-dimensional models are built with a full consideration of fluid flow and heat transfer fields. A trapezoidal channel is developed and its thermal–hydraulic performances are compared with the straight, the S-shape, and the zigzag structures. Nusselt numbers and the Fanning friction factors are analyzed with respect to the changes in Reynolds numbers and structure geometric parameters. A sandwiched structure that couples two hot channels with one cold channel is further designed to match the heat transfer capacity and the velocity of sCO2 flows between different sides. Through this novel design, we can reduce the pressure drop by 75% and increase the regenerative efficiency by 5%. This work can serve as a solid reference for the design and applications of PCHEs.

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