Zhengyuan Pei¹, Yasushi Koito^2,*

Frontiers in Heat and Mass Transfer, Vol.22, No.5, pp. 1381-1397, 2024, DOI:10.32604/fhmt.2024.056624 - 30 October 2024

Abstract Extended experiments were conducted on the oscillation characteristics of merged liquid slugs in a horizontally oriented polymer pulsating heat pipe (PHP). The PHP’s serpentine channel comprised 14 parallel channels with a width of 1.3 and a height of 1.1 . The evaporator and condenser sections were 25 and 50 long, respectively, and the adiabatic section in between was 75 mm long. Using a plastic 3D printer and semi-transparent filament made from acrylonitrile butadiene styrene, the serpentine channel was printed directly onto a thin polycarbonate sheet to form the PHP. The PHP was charged with hydrofluoroether-7100.… More >

Ali M. H. Al-Obaidy^*, Ekhlas M. Fayyadh, Amer M. Al-Dabagh

Frontiers in Heat and Mass Transfer, Vol.22, No.5, pp. 1421-1442, 2024, DOI:10.32604/fhmt.2024.055063 - 30 October 2024

Abstract High heat dissipation is required for miniaturization and increasing the power of electronic systems. Pool boiling is a promising option for achieving efficient heat dissipation at low wall superheat without the need for moving parts. Many studies have focused on improving heat transfer efficiency during boiling by modifying the surface of the heating element. This paper presents an experimental investigation on improving pool boiling heat transfer using an open microchannel. The primary goal of this work is to investigate the impact of the channel geometry characteristics on boiling heat transfer. Initially, rectangular microchannels were prepared… More > Graphic Abstract

Yasser Jebbar^1,2,*, Fadhil Fluiful², Wisam Khudhayer³

FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.6, pp. 1279-1297, 2024, DOI:10.32604/fdmp.2024.050753 - 27 June 2024

Abstract This study includes an experimental and numerical analysis of the performances of a parabolic trough collector (PTC) with and without cylindrical turbulators. The PTC is designed with dimensions of 2.00 m in length and 1.00 m in width. The related reflector is made of lined sheets of aluminum, and the tubes are made of stainless steel used for the absorption of heat. They have an outer diameter of 0.051 m and a wall thickness of 0.002 m. Water, used as a heat transfer fluid (HTF), flows through the absorber tube at a mass flow rate… More >

Ameer Abed Jaddoa^* , Karema Assi Hamad, Arshad Abdul Jaleil Hameed

Frontiers in Heat and Mass Transfer, Vol.20, pp. 1-9, 2023, DOI:10.5098/hmt.20.18

Abstract In the Heat Transfer process, many innovations were introduced aiming to obtain the most optimum behavior of the cooling process using nanofluids as coolant liquids. These nanofluids have gained much attention in cooling systems due to their special rheological and thermal performance. In this work, an experimental evaluation is conducted for nanofluids Al₂O₃, SiO₂, CuO, ZnO, and TiO₂ nanoparticles applied to a mini-channel. The nanofluid particles were entirely spread out in purified water (size of 15 nm) before being passed to the heat sink through a confined inflow channel. The obtained results showed that the achieved improvement… More >

Hussein Al-Gburi^*, Akeel Abbas Mohammed, Audai Hussein Al-Abbas

Frontiers in Heat and Mass Transfer, Vol.20, pp. 1-7, 2023, DOI:10.5098/hmt.20.17

Abstract Transferring thermal energy efficiently necessitates utilizing a heat exchanger capable of producing the full thermal power of the energy supply at lowest possible cost and time. Therefore, in the present investigation, the impact of corrugated helical coil concentric tube-in-tube heat exchanger on the thermal performance is investigated experimentally. As a continuous in our issue of heat exchanger, the corrugated helical tube-in-tube is carried out and compared with smooth helical tube-in-tube for free convection heat transfer. The set-up of the experimental apparatus are designed and utilized to be appropriate for the cooling and heating systems of… More >

O. M. Oyewola^a,b,* , M. O. Petinrin^a , and H. O. Sanusi^a

Frontiers in Heat and Mass Transfer, Vol.20, pp. 1-8, 2023, DOI:10.5098/hmt.20.16

Abstract The flow and heat transfer behaviour of channels with dimples and protrusions of spherical and piriform shapes was numerically explored by solving the Navier-Stokes and energy equations with a CFD software, the ANSYS Fluent 19.3, in the range of Reynolds numbers from 8,500 to 59,000. The values of the Nusselt number and friction factors were estimated and the non-dimensional Performance Evaluation Criterion (PEC) was determined to measure the thermal-hydraulic performance. The results reveal that the piriform protruded channel demonstrated a higher thermal performance with Nusselt number values of 36%, 15%, 23%, and 9% than the… More >

Shintaro Hayakawa^a , Takashi Fukue^a,*,† , Yasuhiro Sugimoto^a , Wakana Hiratsuka^b , Hidemi Shirakawa^c , Yasushi Koito^d

Frontiers in Heat and Mass Transfer, Vol.18, pp. 1-9, 2022, DOI:10.5098/hmt.18.29

Abstract This paper describes the effects of a combination of rib and pulsating flow on heat transfer enhancement in an mm-scale model that simulates the narrow flow passages in cooling devices of downsized electronic equipment. This research aims to develop a novel water cooling device that increases heat transfer performance while inhibiting pumping power. Our recent study has reported that a combination of pulsating flow and rib could enhance heat transfer performance relative to the simple duct. In the present study, to verify the optimal rib height for improving heat transfer by pulsating flow, we evaluated… More >

Marwa M. Ibrahim^a,*, Mohamed Mahran Kasem^b,c

Frontiers in Heat and Mass Transfer, Vol.17, pp. 1-11, 2021, DOI:10.5098/hmt.17.20

Abstract Currently electricity generation technologies by thermal energy conversions become strong demand. The objective of this paper is to present a novel thermal study of absorber/receiver circular pipe of parabolic trough solar collector system for laminar and turbulent (k-ɛ model) fluids flow as well as two-dimensional numerical simulation is performed using CFD ANSYS FLUENT software. Significant improvements in heat transfer and velocity were discovered; the pattern of temperature distribution over the pipe absorber was displayed, and velocity vectors, pressure contours, and temperature contours were studied. The impact of increasing the heat flux towards the pipe wall More >

Shuang Cao^a,*, Hui Yang^a, Luxing Zhao^a, Tao Wang^a, Jian Xie^b,†

Frontiers in Heat and Mass Transfer, Vol.17, pp. 1-16, 2021, DOI:10.5098/hmt.17.17

Abstract Flow boiling heat transfer is an effective way to fulfill the energy transfer. The wettability of boiling surface influences the liquid spreading ability and the growth, departure, and release frequency of bubbles, which determines the heat transfer performance. According to the wettability and combination forms, boiling surface are classified into weak wetting surface, strong wetting surface, and heterogeneous wetting surface. Fabricating by physical, chemical method or coating the original surface with a layer of low surface energy, the weak wetting surface has more effective activation point and nucleation center density to improve heat transfer performance… More >

Sheikh Hassan¹, Didarul Ahasan Redwan¹, Md. Mamun Molla^1,2,*, Sharaban Thohura³, M. Abu Taher⁴, Sadia Siddiqa⁵

Energy Engineering, Vol.118, No.6, pp. 1659-1679, 2021, DOI:10.32604/EE.2021.017657 - 10 September 2021

Abstract A two-dimensional (2D) laminar flow of nanofluids confined within a square cavity having localized heat source at the bottom wall has been investigated. The governing Navier–Stokes and energy equations have been non dimensionalized using the appropriate non dimensional variables and then numerically solved using finite volume method. The flow was controlled by a range of parameters such as Rayleigh number, length of heat source and nanoparticle volume fraction. The numerical results are represented in terms of isotherms, streamlines, velocity and temperature distribution as well as the local and average rate of heat transfer. A comparative More >