Yun Hao^* , Shaohua Lv, Song Wu

Frontiers in Heat and Mass Transfer, Vol.18, pp. 1-8, 2022, DOI:10.5098/hmt.18.3

Abstract Traditional methods of enhancing the thermal efficiency of heating furnaces in continuously producing oilfields, such as replacing existing units with more efficient units or renovating old furnaces, are highly inconvenient. This paper studied on the characteristics of nanofluids, a novel heat transfer medium with excellent heat transfer characteristics to enhance the thermal efficiency of heating furnaces. The stable nanofluids (Al₂O₃-H₂O, SiO₂- H₂O, and TiO₂-H₂O) were prepared by a two-step method and various chemical and physical treatments were carried out. Thermal conductivities of the nanofluids were measured using the transient hot-wire method. Based on the analysis, the most appropriate nanofluid (TiO₂-H₂O)… More >

Amnart Boonloi^a, Withada Jedsadaratanachai^b,*

Frontiers in Heat and Mass Transfer, Vol.18, pp. 1-13, 2022, DOI:10.5098/hmt.18.2

Abstract This study numerically investigates pressure loss, heat transfer and thermal efficiency in round tube heat exchangers attached with various types of Vrings. A typical type A V-ring is compared with two types of modified V-rings (type B and C). The impacts of blockage ratios, b/D = 0.05, 0.10, 0.15 and 0.20 for all V-ring types in the turbulent region are discussed (Re = 3000 – 20,000). Flow directions in the round pipe attached with the V-rings are varied. The V-apex setting downstream is referred to as “V-Downstream, while the V-apex setting upstream is referred to as “V-Upstream”. The flow and… More >

Olanrewaju M. Oyewola^a,b,*, Samuel I. Afolabi^b

Frontiers in Heat and Mass Transfer, Vol.19, pp. 1-6, 2022, DOI:10.5098/hmt.19.38

Abstract Numerical analysis of heat transfer by convection in a square with a rectangular shape heated block located at the top, center and bottommost has been numerically investigated by applying the principal partial differential equations governing mass, momentum and energy using discontinuous Galerkin weighted procedure for residual finite element with the view of examining the significance of position of rectangular shaped heated block encapsulated within the square cavity. The right wall being adiabatic while the other three walls are maintained at low constant temperature. The heated block is maintained constantly hot. The developed code of COMSOL Multiphysics is employed to perform… More >

Ali Chitsazan^a,*, Georg Klepp^a, Birgit Glasmacher^b

Frontiers in Heat and Mass Transfer, Vol.19, pp. 1-8, 2022, DOI:10.5098/hmt.19.35

Abstract The objective of the present research is the prediction of large arrays of impingement jets using a computational model. The heat transfer and the force coefficient from single and multiple jet rows (1, 2, 4, 8, and infinity rows) for two different nozzle shapes as either orifice or straight pipe on a fixed flat surface were numerically investigated for drying applications to understand the physical mechanisms which affect the uniformity of the local heat transfer and pressure force coefficient as well as average heat transfer coefficient. The pipe has always a higher averaged Nu and pressure force coefficient compared to… More >

Rodrigo Vidonscky Pinto^a , Flávio Augusto Sanzovo Fiorelli^b,*

Frontiers in Heat and Mass Transfer, Vol.19, pp. 1-10, 2022, DOI:10.5098/hmt.19.30

Abstract The present paper provides a discussion about the use of constraints in step-by-step optimization algorithms used for the solution of a twodimensional inverse heat transfer problem containing a modeling error. It is observed that the unrestricted algorithms provided better estimates to the power map and the introduction of constraints is harmful to the solution of the inverse heat transfer problem, reducing the area in which this solution approaches the actual heat sources distribution, due to the solution of the unrestricted problem adopting negative values in restricted areas, which compensate the high sensitivity of this problem and consequently provide improved solutions. More >

M. O. Petinrin^a , B. A. Sikirullahi^a, T. T. Olugasa^a, O. M. Oyewola^a,b,*

Frontiers in Heat and Mass Transfer, Vol.19, pp. 1-8, 2022, DOI:10.5098/hmt.19.28

Abstract Tubes are commonly employed in heat exchangers for their ease of production and capacity to sustain high pressure. In this study, the heat and flow transfer behaviour of cam-shaped tube bank in staggered configuration at varying angles of attack 0°to 180° was numerically investigated. The study was carried out by solving the continuity, momentum, energy and realizable k-ε transport equations using the finite volume-based ANSYS Fluent solver. This was performed to acquire the friction factor and heat transfer characteristics in the air inlet velocity range of 9 to 15 m/s. The results showed that the cam-shaped tube bank at varying… More >

Amnart Boonloi^a, Withada Jedsadaratanachai^b,*

Frontiers in Heat and Mass Transfer, Vol.19, pp. 1-13, 2022, DOI:10.5098/hmt.19.26

Abstract CFD analyses of flow characteristics and heat transfer topology in a heat exchanger duct (HXD) placed with three various configurations of the double V-baffles (DVB) are reported. Parameters of interest are DVB height ratios (b/H = 0.05 – 0.25), gap spacing ratios (g = 0.05 – 0.40), flow directions (+x, -x), and DVB configurations (Type I, II and III). Laminar flow with Reynolds numbers (based on the inlet conditions) between 100 – 2000 is measured. The present problem is solved with the finite volume method (a commercial program). Fluid flow and heat transfer characteristics in the tested duct are described.… More >

Farhan Lafta Rashid^a , Abbas Fadhil Khalaf^a, Ahmed Kadhim Hussein^b, Mohamed Bechir Ben Hamida ^c,d,e, Bagh Ali^f, Obai Younis^g,*

Frontiers in Heat and Mass Transfer, Vol.19, pp. 1-6, 2022, DOI:10.5098/hmt.19.21

Abstract Convection and conduction in a fluid flow and a rigid body in contact with each other often occur in engineering situations, resulting in unsteady conjugate heat transfer (CHT). Although the analytical solutions to the separate conduction and convection issues are surprisingly straightforward, the combined conjugate heat transfer problem is substantially more complex to solve. This study investigates the CHT of a fluid (air) passing through an unbounded hemisphere. The hemisphere produces heat at a predictable and regular pace. The governing equations are solved using a finite volume system (FVS) using ANSYS Fluent V.16.0, with axisymmetric, no normal convection, and stable… More >

Olanrewaju M. Oyewola^a,b,*, Samuel I. Afolabi^b

Frontiers in Heat and Mass Transfer, Vol.19, pp. 1-8, 2022, DOI:10.5098/hmt.19.20

Abstract This paper investigates numerically the problem of convective heat transfer and entropy generation by two adiabatic obstacles positioned inside a square cavity heated at the left wall and cooled on the right wall while horizontal walls are adiabatic. The inclination angle of the cavity orientation investigated are 30, 60 and 90 degrees. Rayleigh numbers ranging from 103 to 106 were calculated for two vertical obstacles. The method of Galerkin finite element was employed to solve the conservation equations of mass, momentum and energy. The cavity is assumed to be filled with air with Prandtl number of 0.71. It was observed… More >

Nitesh Kumar, Shiva Kumar^*

Frontiers in Heat and Mass Transfer, Vol.19, pp. 10-11, 2022, DOI:10.5098/hmt.19.10

Abstract In the present study, the use of wavy fin turbulators on the annulus body of a double pipe air heater has been numerically investigated. The inner pipe consists of hot water whereas the annular section consists of cold air whose Reynolds Number (Re) ranged from 3000-15,000. Rectangular crosssectioned wavy fin turbulators with various curvature ratios of 2, 3, 5, and 7.5 is numerically simulated to investigate the influence of curvature effects on turbulence. Results have been compared with the bare pipe and with rectangular straight fins. It is seen that wavy fin turbulators perform better (compared to (other two) bare… More >