ABSTRACT An active method for heat transfer enhancement is proposed and thoroughly characterized for the first time for cryogenic quenching, in which mechanical vibrations are directly induced onto the sample to be quenched, employing a compact modular system composed of a pneumatic plunging device along with a DC motor/eccentric cam mechanism, generating oscillations on three different axes at a wide

ABSTRACT The present experimental study reports the flow and heat transfer characteristics of a synthetic jet issuing from a sharp-edged orifice (diverging-shaped orifice). The experiments are carried out for a varied range of opening angles of sharp-edged orifices (θ = 0°, 30°, 60°, 90°, and 120°), Reynolds number (Re = 3243–8143), different jet-to-surface spacings (z/d = 1–16), and for two different

ABSTRACT The performance of a solar air heater roughened with sine wave baffles has been calculated in terms of effective and thermal efficiency. Relative baffle length ( Lb/LP), relative roughness pitch Pst/e, relative height e/H, angle of attack (α∘), Reynolds number Re, Insolation I and Temperature rise parameter ΔT/I are the operational parameters. The sine wave roughened solar air heater has a

ABSTRACT This study prepares an experimental examination of thermal and hydraulic analysis of an absorber plate integrated with different arrangements of twisted turbulators, including longitudinal, transversal, and oblique orientations. These arrangements are considered for both the integral and the interrupted turbulators over Reynolds number range from 9174 to 55048. Nu ratio and f ratio range from

ABSTRACT In this study, the uniformity factor of the temperature difference field was introduced into the direct contact heat exchanger by establishing a trace element layer model for the heat exchanger. Furthermore, the uniformities of the temperature and temperature difference field of the direct contact heat exchanger operated using a continuous heat source were analyzed. The heat exchange height

ABSTRACT An experimental investigation of the effect of random vibration on the melting behavior of a phase change material (PCM) and the thermal performance of a PCM-based heat sink is presented. While random vibration from 2 to 16 g rms for the frequency range from 15 to 2000 Hz was applied to a rectangular enclosure, which contains paraffin wax and the heat sink, a constant heat flux was imposed

ABSTRACT Four kinds of microchannels with round grooves and ribs were designed: round grooves (round), round grooves and single–sided ribs (round–single), round grooves and odd-symmetric ribs (round–odd), and round grooves and doubly symmetric ribs (round–double). The effects of rib arrangement on the heat transfer performance of microchannels with round grooves and ribs were numerically investigated

ABSTRACT Heat transfer over a heated plate positioned normal to the horizontal circular impinging jet is investigated experimentally. The area average and local heat transfer characteristics over a large plate impinged by jet of air are investigated for Reynolds numbers ranging from 10,000 to 45,000, with jet-to-plate distances of 3–20 d for a maximum range of 0 ≤ r/d ≤ 44. The experiment is carried

ABSTRACT The present work focuses on the experimental and large-eddy simulation (LES) investigation of fluid flow and heat transfer due to the impingement of an unconfined turbulent slot jet on a smooth flat plate. Three LES sub-grid scale models are validated with the experimental observations for first time in terms effect of slot widths. A detailed parametric study is conducted considering nozzle

ABSTRACT In this paper, two special-shaped separated heat pipes with different condensation section structures are designed. The working medium is water, and the filling rate is 65%. The evaporation section is placed in the hot water tank, and the condensation section is equipped with a cold water jacket. The effects of different structures of condensing section on the thermal performance of separated

ABSTRACT A novel regenerative heat exchanger was designed and fabricated for heat recovery of dryer flue gases with a high porosity matrix core that was made of alumina foams. The effects of matrix height, matrix linear speed, and flow rate on thermal effectiveness were investigated based on an L25 Taguchi model. Results show that the matrix height and flow rate are inversely related and the matrix

ABSTRACT We report one of the first experimental investigation on simultaneous mapping of whole field temperature and velocity data to demonstrate the potential of thermographic PIV (or LIP/PIV) in the context of natural convection for a back-wall heated open square cavity. As part of the validation exercise, LIP/PIV-based results are compared with corresponding numerically simulated and interferometry-based

ABSTRACT In this study, the flow and heat transfer characteristics of microencapsulated phase change material (MPCM) slurry were experimentally investigated using a newly designed helical coil heat transfer device. The conventional helical coil has been structurally modified with passive enhancement features aiming to further promote fluid mixing. Specifically, 360° plastic tubing with or without wire

ABSTRACT The PCHE has been recognized as a promising heat exchanger for hypersonic precooled aero-engines due to its superior thermal performance, high compactness and robustness. The present work focuses on the experimental thermal-hydraulic performance study of a novel zigzag microchannel PCHE. The results indicate that the pressure loss caused by friction is the main source. The Fanning correlation

ABSTRACT The spray cooling is investigated for a high-temperature steel plate using varying temperature coolant for different nozzle-plate orientations. Before experimentation with very-high mass-flux spray, droplet-train impact assessment indicates liquid film breakup intensification down the inclined plane. The heat transfer analysis suggests a significant cooling performance change with an inclination

ABSTRACT An experimental setup has been developed to measure the thermal state of a conical antenna cooled by means of porous media saturated with water-based copper nanofluid. Thermal conductivity of the used porous materials varies between 4 and 41.2 times that of the water which constitutes the base fluid of the nanofluid whose volume fraction ranges from 0% (pure water) to 5%. The antenna is placed

ABSTRACT The initial transient behavior of condensation of water vapor from humid air plays vital roles in a large variety of engineering applications. Although such influences on the steady-state attributes of dropwise and filmwise condensations have been widely investigated in the literature, description of their initial transient behaviors is rather limited. Herein we have characterized the initial

ABSTRACT A novel turbulated cutback structure is designed for trailing-edge cooling, which has smooth-transition protrusions on the cutback surface. Experimental investigations are carried out on the effects of the protrusion configuration and the blowing ratio M on adiabatic cooling effectiveness and convective heat transfer coefficient of the cutback surface using transient thermochromic liquid crystal

ABSTRACT This manuscript presents an experimental study on heat transfer and pressure drop of two aluminum lattice-frame materials obtained via additive manufacturing, varying the air flow rate and the electrical power. A round shape and an airfoil shape samples were compared. The second one was proposed to reduce pressure drops. It was measured that pressure drop decreased on average by 5% maintaining

ABSTRACT The paper presents a gas-water heat exchanger based on the technology of a microheat pipe. The heat exchanger parameters, such as inlet and outlet temperature of flue gas, wind speed and inlet and outlet temperature of the water, were measured in practice. The analysis data showed that the temperature difference between the flue gas and the flue gas before and after heat exchange increased

ABSTRACT An experimental investigation is conducted to study the two-phase heat transfer behavior of a shear-thinning Non-Newtonian (NN) fluid, i.e., “Massecuite,” at atmospheric pressure over bi-directional microstructured surfaces for the heat flux range from 70 to 200 kW/m2. Two-phase heat transfer characteristics of a Newtonian Fluid, that is, distilled water, is also studied for the sake of comparison

ABSTRACT Bauxite and silica particles are candidate materials for solar thermal energy storage at high temperatures. The temperature-dependent emittance of packed beds with bauxite and silica particles was measured using a newly upgraded emissometer at wavelengths 2 μm ≤ λ ≤ 16 μm and temperatures up to ~730 K. The room-temperature emittance was obtained from the measured directional-hemispherical

ABSTRACT Three-dimensional reconstructions of thermal field in a differentially heated cylindrical cavity with dilute concentrations of nanofluids as the working medium have been reported. Experiments have been conducted in a specially designed tomography cell filled with dilute concentrations of Al2O3 nanofluids with ethylene glycol dimethacrylate (EGD) as the basefluid. The two horizontal walls of

ABSTRACT The influence of surface structures on the wettability and evaporation of a heated water drop is investigated both in the presence of a graphene layer and without a graphene coating. Different topology of surface roughness changes the structuring of water near nano-micro textures. The structured wall surface changes both the wettability and the evaporation rate. Molecular dynamics modeling

ABSTRACT In this study, a new design has been developed to increase the thermal performance of a plate heat exchanger. In the developed design, springs are placed on the heat exchanger plates at an angle of 45°. In this study, which aims to improve heat transfer by increasing turbulence, nanoparticles were also used to increase the heat transfer coefficient of the heat transfer fluid. The nanoparticles

ABSTRACT Non-uniformity in flow is the veritable situation in the case of heat exchangers and a decisive aspect of the design of heat exchangers. The extensive experimental investigation is ushered for compact three-fluid heat exchanger with cross-flow configuration under three distinct flow non-uniformities at the inlet of central fluid. The maximum augmentation of 3.4% in cooling efficacy is marked

ABSTRACT The parametric optimization of thermal collector having hemispherical protrusion with air jet impingement is carried on effective efficiency criterion. The parameters selected for the investigation are the relative spanwise pitch ( Y/Dh), relative streamwise pitch ( X/Dh), and ratio of the relative protrusion diameter to height ( dpr/epr). A MATLAB program is executed to collect the data,

ABSTRACT The current study investigates the distribution of local heat transfer coefficient, measurement of pressure loss and CHF in a lobed horizontal channel for flow boiling. Lobed channels with different lobed depths of 2.3, 2.0 and 1.25 mm, each having three different channel lengths (400, 600, and 1000 mm), are used for the experiments. The working substance used is R-123 with different mass

ABSTRACT This study reports the results of experimental and numerical investigations on the thermal performance of a miniaturized phase change material (PCM) heat sink coupled with heat pipe. Initial studies are conducted on two different configurations of PCM heat sink with heat pipe (i) HSHP (i.e., PCM coupled at evaporator of heat pipe) (ii) HPHS (i.e., PCM coupled at condenser of the heat pipe)

ABSTRACT The present research work aims at providing data on heat transfer by forced convection from three-dimensional bodies suspended in a free stream of air. The shapes investigated covered cubic and rectangular bodies with air flow parallel and normal to the body’s axis. The experiments were carried out inside an air duct in which air flows over a model for the three-dimensional body. The results

ABSTRACT Flat heat pipe (HP)-phase change material (PCM) hybrid system used for thermal regulation of simulated PV is investigated experimentally. Three PCMs; Rubitherm RT-25 H (RT25), Rubitherm RT-35 H (RT35), and Rubitherm RT-44 H (RT44) coupled with the HP are tested for best cooling system. Impact of using one or two heat sinks compared with PCM only is studied. The results show that RT25 achieves

ABSTRACT Taking into consideration of the phase transition of silicon, the threshold prediction model of the melting starting and completion and vaporization starting and completion irradiated by laser with pulse width from 400 fs to 1 ms and 1064 nm wavelength is established based on the results of temperature field. The laser-induced ablation threshold of silicon is measured experimentally. The variation

ABSTRACT The effect of variation in open area ratio (β) in a multi-V rib roughened Single-Pass Solar Air Heater (SPSAH) is analyzed in this work. Fixing values of other parameters, such as open area ratio (β) and relative roughness width (W/w), were studied with a certain range of Reynolds number (Re) ranging from 2000 to 18000. The improvement in Nusselt number ratio (Nu/Nus) and thermo-hydraulic

ABSTRACT In this study, the effect of the constant magnetic field (MF) on the convective heat transfer characteristics of Fe3O4/H2O ferro-nano-fluid with different nano-fluid volumetric concentrations (1.0%, 2.0%, and 5.0%) flowing in a circular pipe has been studied experimentally. Experiments have been conducted under laminar flow regime (1000≤ Re≤2300). Based on the experimental data, a good agreement

ABSTRACT During the freezing process, water migration is a decisive factor for the estimation of frost heave and thaw-settlements of fine and mixed-grain soils. One-dimensional freezing tests with and without a water supply were carried out. The influence of different temperature gradients of a saturated clay on parameters such as water intake, frost heave, and thaw-settlements is discussed here. A

ABSTRACT An experimental study was performed to determine the effect of angle of attack on the thermal-hydraulic performance of a cam-shaped tube with constant heat flux in crossflow. The Reynolds number based on an equivalent diameter was in the range of 15500 < ReDeq< 42000, and the angle of attack (α) varied from 0° to 180°. For the heat transfer experiments, five different heat fluxes were considered

ABSTRACT A common heat exchange method used for most new designs is the use of heat sinks such as short pin fins. This experimental study investigated the static pressure characteristics developed in a short pin fin. Different fin array arrangements, fin longitudinal and transverse spacing ratios and individual slot heights in the fin were investigated. It was found that the row removed arrangement

ABSTRACT The nucleated pool boiling heat transfer experiments for plain and five different reentrant cavity copper tube surfaces in saturated R134a, R32, and R600a have been carried out. The experiments are carried for heat fluxes ranging from 6.92 to 51.71 kW/m2 at saturation temperatures of 7°C and 10°C. A significant increase in the boiling heat transfer coefficient has been observed for all tube

ABSTRACT This paper presents an inverse methodology to estimate the parameters of the non-uniform heat generation (function estimation) within a flat plate assembly using steady-state conjugate heat transfer experiments on the flat plate assembly. Steady-state laminar conjugate forced convection experiments on a flat plate assembly are conducted on a horizontal wind tunnel to estimate the parameters

ABSTRACT In this paper, a numerical-experimental investigation was performed for estimation of the local convective heat transfer coefficients of a two-phase pulsating heated jet impinging a cold disk-shaped mass. By solving the energy equation, temperature history of thermocouples was obtained and then using the “temperatures measured” at locations of the sensors and the “temperatures calculated”

ABSTRACT This paper experimentally and numerically studied the effects of inserting circular rings with four angular indexes and three diameter ratios at Re = 5000–24000 using air as the working fluid in a pipe. Researchers have proposed obstacles with various geometries to improve thermal performance in heat exchangers. However, research has not fully addressed the application of circular ring obstacles

ABSTRACT The current research presents an experimental study on heat transfer and fluid flow characteristics of a helical plate heat exchanger (HP-HEx). Helical plate with different pitches and cross sectional area of the flow channel was investigated for various fluid mass flow rates and inlet temperatures. The results show that the proposed heat exchanger performed an overall heat transfer coefficient

ABSTRACT The present experimental investigation incorporates the winglet twisted tapes as an insert to determine the thermal and hydraulic performance of a heat exchanger tube. The purpose of connecting the winglet to the twisted tape is to improve the heat transmission while minimizing the pressure loss by not disrupting the flow at the core portion. The thermal performance of a heat exchanger with

ABSTRACT When the vehicle cooling system works in negative gauge pressure environment of plateau, it will face the problem of reduced heat transfer performance, which will lead to an increase in vehicle energy consumption. So, there’s important meaning in studying the thermal-hydraulic performance of heat exchangers and optimizing the design of which for negative gauge pressure environments. In this

ABSTRACT In the paper, an experimental work examining the impact of βGa2O3/water nanofluid turbulent flow through a microscale backward-facing step has been conducted. The Reynolds number range of 5,000 to 10,000 has been applied. Numerical simulation was conducted to validate the current experimental study. The results indicated a significant increase in the Nusselt number compared to the base fluid

ABSTRACT In this study, the effects of surface roughness (Ra) on single-phase and two-phase cooling performances of HFE-7100 and water under different coolants, pressures, and subcoolings were studied. The eight surfaces were unidirectionally roughened. A general trend was that the heat transfer increased with increasing Ra. Owing to the larger contact angle and fewer nucleate sites, the smoother surface

ABSTRACT The present study aims at the investigation of the transition of the natural convective flow in a water-filled differentially heated cubic enclosure. The schlieren-particle image velocimetry (PIV) system has been developed and employed for simultaneous measurement of ray-averaged velocity and temperature fields from transient schlieren images for distinct Rayleigh number (Ra) (1 × 107 ≤ Ra

ABSTRACT This study developed a combustor with silicon carbide (SiC) microchannels cooling (SiC MC) at the walls by the motivation of the excellent physical properties of SiC and its promising application in aerospace areas. Its thermal and combustion performance was experimentally explored by the comparison of a combustor with stainless steel microchannel cooling (STS MC). Results showed that the

ABSTRACT Heat transfer coefficient (HTC) was experimentally measured for saturated and subcooled pool boiling of binary mixtures of water and glycerin. Saturated boiling was studied for mixtures with water mass fractions ωw from 100% to 60% on horizontal flat nickel-plated surfaces at heat fluxes from 50 to 650kWm−2 at atmospheric pressure. Subcooled boiling was investigated in the range of subcooling

ABSTRACT This paper shows the design and experimental analysis of a dual generator/condenser component for an absorption heat transformer (AHT) of 2 kW operating with H2O/LiBr, and heat exchangers with four nested helical coils in series. This design shows a compaction ratio of 5.26 × 104 Wm−3/K in the generator and 1.58 × 104 Wm−3/ K in the condenser (higher than in the literature). This AHT can research

ABSTRACT Rotating packed beds (RPBs) have been explored for process intensification in thermal systems using air-water as working fluids. The thermal performance parameters such as cooling range, evaporation rate, heat transfer rate, Merkel number, and effectiveness for the RBP were experimentally evaluated for the airflow rate (0.0072–0.0201 kg/s), water flow rate (0.033 and 0.066 kg/s), and water

ABSTRACT Active and passive techniques have been utilized together to enhance heat transfer in this study. The ferronanofluid, magnetic field, and dimpled tube have not been utilized together in the literature so far. Regarding this issue, this investigation is the first experimental study to specify the effect of use of these three effects simultaneously. The concept of this study is to determine

ABSTRACT In this research work, pool-boiling heat transfer is conducted with the consideration of TiO2 hydrophilic nanoparticles as coating material using Electrospray Deposition (ESD) method. The study focused on the impact of spray parameters such as injection flow rate, solution concentration, and spray time on the formation of the coating structure, porosity, cavity characteristics, and thickness

ABSTRACT After analyzing the effect of perforation in a single pass solar air heater in part A, an experimental comparative study was performed on a Double Pass Parallel Flow Solar Air Heater (DPPFSAH) roughened with continuous and perforated multi-V rib roughness. In DPPFSAH, for perforated rib roughness, the gain in Nu/Nus, f/fs, and Thermo-hydraulic performance parameter (THPP) for W/w = 6 are 8

ABSTRACT In this paper, an experimental device for falling film dehumidification of circular tube is established. The effects of desiccant inlet concentration(30%-40%), velocity(0.01–0.06 m/s), temperature(26–36°C) and air inlet velocity(0.7–1.2 m/s), temperature(26–36°C) and moisture content (15–25 g/kg) on heat and mass transfer dynamic process and the internal detailed temperature, velocity were

ABSTRACT Impingement cooling is conducive to enhancing the cooling performance of turbine blade trailing edge channel, and slot ejection can be adopted for additional cooling. This paper explores the influence of the chordwise length ratio of the impingement cavity to the ejection slot on the channel’s heat transfer and friction factor. In the experiment, three models with the chordwise length ratios

ABSTRACT In this paper, an experimental investigation is conducted to investigate the cool-down behavior of single-stage Gifford-McMahon type pulse tube cryocooler. Nine different cold head configurations of pulse tube cryocooler have been fabricated with different aspect ratios of regenerator and pulse tube to investigate their effect on the cooling process. Additionally, experimental investigation

ABSTRACT In the present work, the exergetic efficiency ηexg of a solar heat collector with air jet impingement on an internal conical ring-roughened absorber plate has been analytically determined. The motivation behind the present investigation is to determine the performance of the selected heat transfer enhancement technique in order to bring out the feasibility of the investigation. The geometric

ABSTRACT Experimental investigations on the pool boiling heat transfer enhancement and mechanisms for micropillared surfaces are performed. Two square micropillared MP 50–50 (Square) and MP 50–450 (Square)) and a circular micropillared MP 50–250 (Circular)) are fabricated on a copper substrate. Experimental results show that bubbles easily nucleate at the sharp corners of the square micropillars and

ABSTRACT The present paper reports the thermal behavior of flat and curved surfaces with impinging jets employing circular and elliptical nozzle for identical equivalent diameter (de). Tests are performed with the Reynolds number varying from 11,250–22,500, varied range of plate to nozzle distance (z/d = 1–6), various nozzle aspect ratios (AR = 1–4). A comparison of thermal behavior between flat and