Thermal performance and optimization of hyperbolic annular fins under dehumidifying operating conditions – analytical and numerical solutions

2016 ◽  
Vol 65 ◽  
pp. 42-54 ◽  
Author(s):  
S. Pashah ◽  
Abdurrahman Moinuddin ◽  
Syed M. Zubair
Keyword(s):  
Thermal Performance ◽  
Numerical Solutions ◽  
Operating Conditions ◽  
Analytical And Numerical Solutions ◽  
Annular Fins

A 3-Dimensional Numerical Thermal Analysis for the Configuration Effect of a Single and Double U-tube on the Borehole Performance

2021 ◽  
Author(s):  
Ali H. Tarrad
Keyword(s):  
Thermal Performance ◽  
Heat Load ◽  
Numerical Solutions ◽  
Parallel Flow ◽  
Operating Conditions ◽  
Thermal Design ◽  
Inlet Temperature ◽  
Pump System ◽  
Heat Pump System ◽  
3 Dimensional

Abstract The thermal design of a borehole is the most important task in the thermal performance evaluation of a geothermal coupled heat pump system. It demands an understanding of the U-tube orientation and configuration in the borehole. The COMSOL Multiphysics 5.4 software was utilized in a 3-dimensional numerical simulation model to investigate the thermal performance of a single and double U-tube embedded in the borehole. The water was chosen as a thermal fluid carrier and circulated in the borehole heat exchanger at a mass flow rate range of (0.14–0.34) kg/s and inlet temperature of (33) °C. The configurations of the double U-tubes were assigned as a parallel flow in a cross U-tube arrangement (PFCD), a parallel flow in a parallel double U-tube in situ (PFPD), a series flow circuiting in a cross double U-tube geometry (SFCD), and a series flow in a parallel double U-tube installation (SFPD). The steady-state numerical solutions were compared at fixed borehole configuration and fixed operating conditions. Results showed that the (PFPD), (PFCD), and (SFPD) U-tube configurations have achieved a higher heat load than that of the single U-tube ones by (16–19) %, (13–16) %, and (15–18) % respectively. They produced a higher heat load than that of the series flow in a cross double U-tube (SFCD) arrangement by (30–31) %, (27–30) %, and (29–31) % for the (PFPD), (PFCD) and (SFPD) configurations respectively.

Thermal Performance Analysis of a Rectangular Longitudinal Finned Solar Air Heater With Semicircular Absorber Plate

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Satyender Singh ◽  
Prashant Dhiman
Keyword(s):  
Thermal Performance ◽  
Numerical Solutions ◽  
Solar Air Heater ◽  
Duct Flow ◽  
Balance Equations ◽  
Absorber Plate ◽  
Ansys Fluent ◽  
Air Heater ◽  
Glass Cover ◽  
Good Agreement

Thermal performance of a single-pass single-glass cover solar air heater consisting of semicircular absorber plate finned with rectangular longitudinal fins is investigated. The analysis is carried out for different hydraulic diameters, which were obtained by varying the diameter of the duct from 0.3–0.5 m. One to five numbers of fins are considered. Reynolds number ranges from 1600–4300. Analytical solutions for energy balance equations of different elements and duct flow of the solar air heater are presented; results are compared with finite-volume methodology based numerical solutions obtained from ansys fluent commercial software, and a fairly good agreement is achieved. Moreover, analysis is extended to check the effect of double-glass cover and the recycle of the exiting air. Results revealed that the use of double-glass cover and recycle operation improves the thermal performance of solar air heater.

scholarly journals A Nonlinear Inverse Design Problem for a Pipe Type Heat Exchanger Equipped with Internal Z-Shape Lateral Fins and Ribs

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6424
Author(s):  
Cheng-Hung Huang ◽  
Chih-Yang Kuo
Keyword(s):  
Heat Exchanger ◽  
Thermal Performance ◽  
Design Problem ◽  
Direct Problem ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Design Variables ◽  
Non Linear ◽  
Inverse Design Problem ◽  
Η Value

A non-linear three-dimensional inverse shape design problem was investigated for a pipe type heat exchanger to estimate the design variables of continuous lateral ribs on internal Z-shape lateral fins for maximum thermal performance factor η. The design variables were considered as the positions, heights, and number of ribs while the physical properties of air were considered as a polynomial function of temperature; this makes the problem non-linear. The direct problem was solved using software package CFD-ACE+, and the Levenberg–Marquardt method (LMM) was utilized as the optimization tool because it has been proven to be a powerful algorithm for solving inverse problems. Z-shape lateral fins were found to be the best thermal performance among Z-shape, S-shape, and V-shape lateral fins. The objective of this study was to include continuous lateral ribs to Z-shape lateral fins to further improve η. Firstly, the numerical solutions of direct problem were solved using both polynomial and constant air properties and then compared with the corrected solutions to verify the necessity for using polynomial air properties. Then, four design cases, A, B, C and D, based on various design variables were conducted numerically, and the resultant η values were computed and compared. The results revealed that considering continuous lateral ribs on the surface of Z-shape lateral fins can indeed improve η value at the design working condition Re = 5000. η values of designs A, B and C were approximately 13% higher than that for Z-shape lateral fins, however, when the rib numbers were increased, i.e., design D, the value of η became only 11.5 % higher. This implies that more ribs will not guarantee higher η value.

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