Experiments have been conducted on a flat rectangular loop heat pipe with water and methanol at heat loads from 40 to 320 W at three orientations of the heat pipe (0°, 45°, 90°) and two filling ratios (33% and 50%). Performance parameters such as thermal resistance, effective thermal conductivity and capillary limit are calculated from the experimental data. The results exhibited that the thermal performance

Low-pressure refrigerants such as R245fa allow compact design of IT cooling systems intended for harsh environments. Nucleate boiling of R245fa on an electrically heated flat horizontal surface was experimentally studied. Heat fluxes q w were 30–65 k W / m 2 and saturation temperatures 40–70   ∘ C. Results show that the heat-transfer coefficient HTC increases with both heat flux and temperature, and

Steady-state experiments are conducted under the laminar forced convection heat transfer mode for the cooling of seven asymmetric IC chips (heat sources) mounted at different positions on the substrate board. The board is oriented at different angles, i.e., at 0° (horizontal), 30°, 60°, and 90° (vertical) to study its effect on the cooling of the IC chips. The goal is to determine the optimum configuration

An experimental study on the antifouling performance of ultrasonic and/or electronic treatment was carried out in a convective heat transfer process by using a fouling monitor system. An ultrasonic device was used in a frequency of 28 kHz and a power of 80 W, and a low-voltage electronic processor also used with a maximum current of 0.8 A for water treatment. The experimental results showed that both

This work aims to estimate the experimental heat transfer coefficients of a circular channel using artificial neural network. The experiments are carried out at a forced turbulent flow regime of 10,000 < Re <50,000. The obtained experimental Nusselt numbers are compared using the ANN (Artificial Neural Network). In the developed ANN structure are showed mean square error (MSE), average relative deviation

The purpose of this experimental study is to measure the drag and heat transfer coefficients of the non-circular tubes including square, elliptic, and cam-shape tubes in a turbulent air cross flow. Studies have been made at 0° to 180° angles of attack ( α ) and Reynolds numbers (Re) based on the equivalent diameter of a circular tube within the range of 1.4 × 104 < Reeq < 7.5 × 104. The equivalent

An experimental study has been performed to analyze the heat transfer characteristics by impinging a hybrid nanofluid jet on horizontal-heated test surface. The Ag/ZnO nanoparticles are synthesized and dispersed in DI water Φ = 0.02% to 0.1% by volume. A set of experiments were performed to calculate heat transfer coefficient and boiling performance at varying Reynolds numbers ranging from 1769 to

The current paper is focused on the experimental investigation of the turbulent forced convection with circular-hole spring tape (CHST) inserts in a circular tube. The CHST inserts with different hole and spring ratios, are investigated for a wide ranges of Reynolds number (10,000–50,000). Results show that use of CHST provides an increase in heat transfer by 35% and 51% when assessed with other inserts

It is hypothesized that the heat transfer in microgravity bubbly flow boiling can be computed through a single-flow simulation that accounts for the acceleration of the liquid as bubbles form since the slip velocity in microgravity is negligible. Measurements within the bubbly flow regime were obtained in a 6 mm ID sapphire tube in microgravity using HFE-7000 at four mass fluxes, six heat fluxes, and

Effect of upward two-phase gas-liquid flow on the rate of liquid-solid mass transfer in a bubble column equipped with a horizontal tube bundle was studied by measuring the rate of the diffusion-controlled dissolution of copper in an acidified K2Cr2O solution. Variables studied included gas (nitrogen) flow rate, liquid flow rate, and the number of tube arrays. Data were successfully correlated by a

Impact of using V-cuts twisted tape insert and phase change material (PCM) dispersed mono or hybrid nanofluid on the hydrothermal characteristics of the double tube heat exchanger is experimentally investigated. Water-based Al2O3 and PCM nanofluids and Al2O3+ PCM hybrid nanofluid with different concentrations are used in inner tube. Influences of various geometric parameters of V-cuts twisted tape

In this experimental investigation, the impact of engine load, compression ratio, and percentage blends of biofuel on exergy, energy, and sustainability parameters for the samples of diesel based (10–40% v/v) biodiesel blends were performed on variable compression ratio engine. The brake thermal efficiency, exergy efficiency, engine sustainability, exergy destruction rate, and other exergy parameters

A version improving the efficiency of the Trombe-type assembly is proposed in this study. It consists in equipping the wall with a series of inclined fins forming open cavities of parallelogram section affecting the aerodynamics of the active cavity. The natural convective flow leads to an increase in natural convective heat transfer and improves the overall performance of the assembly. The experimental

Critical Heat Flux (CHF) is one of the catastrophic failure modes encountered in two-phase flows in nuclear, chemical, and power industries. Considerable research was carried on CHF in last few decades in horizontal, inclined, and vertically upward flows. Only limited information, mostly at atmospheric pressure conditions and including CHF enhancers like inlet throttling, was available on CHF in vertical

The present study aims to investigate the effects of the pin on flow and heat transfer from pulsating jet impinging on a heated flat surface. A row of cylindrical pins has been applied on a flat plate with a constant heat flux of 2000 W/m2. The experiments have been performed for two jet to target surface distances, frequency range from 50 Hz to 100 Hz and jet Reynolds number from 7000 to 15000. The

The K, E, and J-types of coaxial thermocouples have been designed and fabricate to perform transient heat flux evaluation at the combustion chamber of a four-stroke diesel engine. These coaxial thermocouples are quite efficient in short-duration transient measurements due to the response time of these instruments are in the rage of milliseconds or less. Using water plunging technique, the thermal product

In the present study, an experimental investigation of performance evaluation of plate heat exchanger (PHE) with the rough surface using AL2O3/water nanofluid was achieved. The experiments were developed for different surface roughnesses of 0.978 µm (smooth surface), 1.276 µm, 2.825 µm and 3.657 µm with different volume fractions of nanoparticles of 1.2 vol.%, 1.9 vol.% and 2.6 vol.% at Reynolds number

Mixed convective heat transfer from horizontal isothermal elliptic cylinder is experimentally studied. Three elliptic test cylinders with same perimeter and length are studied giving axis ratio (AR) equal 1, 0.709 and 0.496. The corresponding Gr for the three test sections is 9.8 × 105, 1.5 × 106, and 2.1 × 106, and Re varies from 111 to 1306. Consequently, the corresponding Ri is in range of 1 to

Experimental results of natural convection in an open-ended concentric and eccentric annulus with helical fin on internal tube are presented. The boundary condition investigated is constant temperature for the inner tube while the outer tube is insulated. The effect of pitches and fin diameter under several different constant temperatures applied on the inner tube at concentric and different eccentric

An experimental study of average heat transfer from air jet impinging on a rough plate by a micro cubic pin is investigated. The main objective of the present study is to investigate the effect of a roughened degree on both local and average Nusselt number. The micro cubic size is (400 µm × 400 µm) with different depths (100, 200, and 300 µm). Therefore, the roughened degree varies between 1.0 (considered

We presented both experimental and numerical studies on the freezing of impacting water droplets on a cold surface at different surface temperatures. The numerical model consists of two parts. The first one is to determine the temperature evolution of the droplet prior to the occurrence of freezing by solving the heat conduction equation, and the second one is to simulate the freezing process via an

In this experimental study, the effect of natural convection during the melting and solidification process on nano-enhanced phase change material in a designed cylindrical thermal energy storage system has been investigated. The temperature variations at both axial and radial locations are measured for stearic acid PCM with variation in mass fractions (0.1%, 0.3%, and 0.5%) of Al2O3 nano-additives

Studies have previously looked at the transport processes in convection but there is a lack of detail on methods to characterize transient heat transfer behavior. An infrared methodology to spatially and temporally resolve transient heat transfer is presented and tested on turbulent impinging (cooling) jets (non-swirling, swirling, Re = 11,600 to 35,000, S = 0 to 1.05). The intricacies of data filtration

The near-azeotropic refrigerant mixture R1234ze(E)/R152a (40/60 by mass%) was an excellent alternative refrigerant with outstanding environmental protection and thermophysical properties as well as good cycle performance. The flow boiling heat transfer characteristics of R1234ze(E)/R152a (40/60 by mass%) in horizontal smooth copper tube with inner diameter (ID) of 6 mm were investigated experimentally

Pool boiling is the process in which the heating surface is submerged in a large body of stagnant liquid. In the present work, heat transfer in nucleate pool boiling is modeled both experimentally and semi-analytically with the consideration of surface structuring methods including wire electrical discharge machining (WEDM) and etching. The developed models consider variations of nucleation site density

The cross flow over the tube bank is extensively employed in the heat exchangers. The present study investigates the heat transfer and frictional losses of cross flow tube bank with solid and perforated splitter plates. The experimental data are collected for bare tube bank, tube bank with solid and perforated splitter plate by varying the splitter plate width ratio (Rw) and the perforation index (Pi)

A dual-wavelength Mach–Zehnder interferometer technique is used for the investigation of thermodiffusion through 5 mass% NaCl solution at temperature differences of 3°C, 5°C, and 8°C applied across the cavity. Initially, the values of thermal diffusivity and thermodiffusion coefficients are measured from the highly sensitive data of temperature and concentration distribution through sensitivity analysis

Saline soils is porous medium whose thermal conductivity is affected by components and particle shape. However, the particle shapes in geomaterials are various, and the component and its content are in dynamic change as the soil varies between unfrozen and frozen state. In this study, based on the theory of multi-phase medium mixed geothermal conductivity, a new model is developed to explore the dynamic

Previous researches mainly focused on the cooling performance of the vortex tube. Here, the heating performance indicators such as hot temperature difference, heating rate per unit air, and coefficient of performance are investigated experimentally. The results show that the maximum heating separation is obtained when the cold mass fraction is in the range of 0.45–0.7. The influence of inlet pressure

Rates of mass transfer in a spiral coil were measured by a technique involving the diffusion-controlled dissolution of copper in acidified dichromate. The variables studied were solution velocity, spiral tube pitch, and physical properties of the solution. The data were correlated by the equation Sh=0.189Sc0.33De0.55Pd0.29 For a given set of conditions, the mass transfer coefficient predicted from

The current study presents the energy and exergy analysis of a thermoelectric waste heat recovery system of an automobile using an aluminum-based heat exchanger. The experiment was conducted on a 4 cylinder direct injection diesel engine by varying the load with constant engine speed. Effect of second law efficiency, availability, entropy generation along with output current, and power of the thermoelectric

Flow boiling experiments were conducted in a staggered array micro pin fin channel heat sink with deionized water for two-phase pressure drop and boiling heat transfer at constant heat flux. Micro pin fin is a diameter of 400 μm, height of 700 μm and spacing of 300 μm on copper heat sink. From the experimental results, at a vapor quality up to 0.043, the boiling heat transfer found to decrease as the

Thermal characteristics of water in a ground U-tube with twisted tape inserts were addressed. At inlet temperatures of 60°C to 75°C, and Reynolds numbers of 3000 to 9000, the surface heat transfer coefficients for water with twisted tapes ranged from 442 to 897 W m−2 K−1, which were higher than that in smooth tube, 384–810 W m−2 K−1. Average convective heat transfer coefficient for the smooth tube

The studies of nested helical coil heat exchangers for an absorption heat transformer are very limited, although this arrangement has a greater heat transfer area in a smaller volume. The heat exchangers are vertically placed to develop the desorption, condensation, evaporation and absorption processes by falling film mode. The usage of energy from point of qualitative view in these times is mandatory

The drying performance of typical solid wastes (cotton fabrics and plastic debris) in nuclear power plants was evaluated in a bench-scale microwave-combined hot air setup (air temperatures: 90–130°C; microwave power: 200–800 W). The required time of plastic debris in continuous microwave-combined hot-air drying reduced by about 67% and 68% compared to hot-air and microwave drying, respectively, and

A number of theoretical studies and experimental investigations have been carried out on the closed loop flat plate oscillating heat pipe (CLFP-OHP) in the past decades. However, due to the complex working mechanism of CLFP-OHP, the effects of operational and geometrical parameters on the thermal performance CLFP-OHP have not been completely revealed so far. In the present study, the CLFP-OHP was investigated

The influences of shape characteristics and pressure on n-Heptane ring fire were investigated through two groups of experiments. In group A, the ring fire with varying shape characteristics was conducted. In group B, the ring fire was performed under sub-atmospheric pressures including 45 kPa, 60 kPa, 75 kPa, and 90 kPa. The results show that the mass loss rate is determined by combined results of

The wellbore injected with heating fluid requires temperature field prediction to formulate production strategy. The classical radial heat transfer calculation of wellbore takes into account the thermal conductivity resistance of casing, cement sheath and formation, ignoring the “Thermal Contact Resistance” caused by the micro-annulus at the cementing interface. In order to study the influence of micro-annulus

The effect of helix angle and pitch ratio of helical surface disc turbulators on the thermal performance of double pipe heat exchanger are discussed in this study. Tests are performed with air as working fluid for different pitch ratios, numerous helix angles, and various Reynolds number. Water and air are allowed to flow along inner tube and through annulus, respectively. In each case, the thermal

The enhanced heat transfer performance of falling film evaporation during desalination through altering smooth tubes by corrugated tubes was investigated. An experimental research on corrugated and smooth tubes was carried out using a horizontal-tube falling-film evaporation heat transfer experimental apparatus. The changes in heat transfer coefficient with the process parameters (sprinkling density

Spray fire is one of the most frequent fire accidents in ship engine compartments, drawing much attention to spray fire safety. Currently, a series of spray fire tests was conducted in a 2.0 m (L) × 2.0 m (W) × 1.88 m (H) enclosed compartment. Experimental results indicate that the combustion process can be divided into three stages and the injecting pressure has significant effect on the flame height

The effect of impingement jet on heat transfer in a rotating wedge-shaped ribbed trailing edge was experimentally investigated in this study. The inlet Reynolds number varied from 10000 to 61000, and rotation number from 0.06 to 0.16. Four different impingement structures (angle, diameter and number of impingement jet holes) were selected for investigation in non-rotating state, whereas the basic model

An experimental investigation on condensation heat transfer of R290 with inside diameter of 6.3 mm in horizontal micro-fin tube was presented. Effects of each case on the condensation heat transfer coefficient of R290 were analyzed at saturation temperatures of 40°C, 50°C, and 55°C with heat flux ranging of 3–8 kW/m2, mass flux ranging of 100–250 kg/(m2·s) and vapor quality up to 1.0. The results show

A comprehensive study for testing of cylindrical heat pipe has been carried out with a number of experiments. Characteristics and performance of heat pipe were evaluated individually with water, methanol, and acetone at different inclination angles (θ). Results obtained show that heat pipe charged with acetone has the smallest thermal resistance and highest heat transfer coefficient compared to other

In order to study heat transfer in cellulose cork, Novolac aerogel with features including large surface area and low-thermal conductivity was used as filler. Novolac colloids result in cork micropores packing and minimize convection heat transfer. Novolac aerogel was synthesized through sol–gel at saturated vapor of solvent atmosphere. A small amount of Novolac enables cork nanocomposites to have

Experiments were performed to investigate the transient cooling characteristics of intermittent spray cooling (ISC) in single-phase and nucleate-boiling regimes. The consumption of residual liquid in the non-injection period was confirmed via observations of the dynamic behavior through visualization experiments. The time variation of the surface heat transfer is relatively small in the single-phase

In the present research work, heat transfer and friction characteristics of in-line elliptical tubes are studied experimentally and numerically with the aiming to enhanced the thermal performance. The elliptical tubes with an aspect ratio (AR) of 0.35 and 0.50 and with circular tubes of the aspect ratio of 1 are selected for Reynolds number (Re) ranging from 5000 to 21000. The results indicate that

The influence of serrated circular rings with rectangular winglets (SCRWRW) on the thermal performance of circular tube heat exchanger has been studied experimentally and computationally. The geometrical parameters considered are diameter ratio (DR = 0.8, 0.85), pitch ratio (PR = 3, 4), attack angle (ϴ = 15°, 30°, 45°), and blockage ratio (0.05). The test section is a circular tube of length 1.5 m

Circular ring inserts are found to enhance the heat transfer rates in the tube flow, while perforations in the ring inserts mitigate the frictional losses. In this study, the geometry of perforated ring is modified by creating lanced holes with a deflector. The experimental data for lanced ring are collected by varying the pitch ratio from 3.33–6.66 and diameter ratio from 0.5–0.6 in the Reynolds number

Thermal characteristics in a vertical spiral-tube ground heat exchanger were addressed. The influences of backfill materials (sand/bentonite/graphite blend) and operation modes were examined. In the heating and cooling modes with Reynolds number of 2500, the integrated evaluation factors of tube in blend rose all by about 20% compared with in sand. The longer recovery time was helpful to improve the

Multistage membrane distillation units connected in series for water desalination is considered. The influence of the number of stages and the module length per stage on the overall economics is investigated via simulations using a validated model. Depending on the degree of feed salinity, a suboptimal condition occurs at a structure size of 40 ~ 35 stages with an average module length of 15 ~ 12 m

Present work deals with the experimental and computational investigation of thermal properties and fluid flow characteristics on circular tube with elliptical inserts. The major axis is taken equal to hydraulic diameter i.e. 6.81cm. A new parameter, height ratio (γ = b/D) has been defined with three values – 0.45, 0.66, and 0.74. The test section is 1.5 m long which is provided with a constant heat

The paper presents the results of experimental and theoretical studies of temperature fluctuations at the surface of heaters in different heat transfer regimes. Developing several methods of treatment for the temperature fluctuations, we succeed in the diagnosing the onset of transient boiling regimes. The proposed methods are based on the statistical analysis of histograms and amplitude-frequency

Experiments on subcooled flow boiling have been carried out to investigate the dynamical parameters and thermal impact of a growing vapor bubble under vertically upward and downward flow configurations with water as the fluid medium. Bubble growth and detachment phenomena have been visualized in real-time using high-speed rainbow schlieren technique. Schlieren-based imaging technique simultaneously

This paper reports the results of a study to investigate and develop correlations for the parameters affecting the time for complete solidification and fusion in spherical shells. For this study, four spherical shells of 35, 76, 106 and 131 mm diameter were used, the charging temperature was varied from −20°C to −5°C while the melting temperature varied from 10°C to 25°C. Water and mixtures of water

In order to establish a reliable procedure for estimation of heat transfer coefficient, experiments on plate finned tube heat exchangers have been conducted on five exchangers. Using own and previously published experimental data databank of 969 working regimes, a new correlation was formed. Correlation is based on hydraulic diameter and porous velocity and on the ratio of characteristic surfaces of

Heat transfer performance and flow characteristics in the Helically Coiled-Twisted Flat Tube (HCTFT) are studied by a numerical simulation. According to the results, the secondary flow caused by the twisted structure destroys the velocity boundary layer, decreases the thermal-conduction resistance, increase the turbulence kinetic energy. The heat transfer performance of HCTFT is greater than Helically

Heat transfer augmentation in solar air heaters (SAHs) can be achieved economically and conveniently using artificial roughness elements on the absorber surface. Cubical roughness elements used in this investigation produces better heat transfer characteristics. However, this enhancement is particularly accompanied by increased pumping power due to increased friction. This study presents the results

Heat transfer and fluid flow characteristics in a round tube fitted with Hexagonal ring turbulators were studied. Hexagonal ring turbulators with the different inner diameters (diameter ratio 0.6, 0.7 and 0.8) and Pitch Diameter Ratio of 1, 2 and 3 were used as flow blockage geometry. Parameters varied during the tests were diameter ratio, Pitch Diameter Ratio, and Reynolds number. Air with ambient

With the stricter requirements for energy saving and emission reduction, air preheaters have always been the focus of scientific research, especially the development of plate air preheaters with high compactness, good heat transfer performance and reduced media flow pressure has a sharp upward trend. At present, there are two kinds of plate type air preheaters on the market, one is popular in the market