R134a was recognized as probably one of the most important refrigerants of the two past decades. Among the proposed alternative fluids, there are certainly isobutane (R600a) and R152a. This article presents about 200 new heat transfer coefficient and pressure drop data obtained during flow boiling of R152a and R600a inside a smooth copper tube having an internal diameter of 4 mm. Three saturation temperatures

In this paper, a three dimensional Computational Fluid Dynamics Model (CFD) model was generated for spray cooling of straight parts by using a single point nozzle. The numerical simulations of spray quenching were performed to investigate the cooling rate of a 22MnB5 hot steel blank commonly used material in the automotive industry. Experiments are carried out to examine infrared thermograph of hot

Excellent ultra-thin heat pipes (UTHP) require a wick with high capillary force (ΔPc) and a good permeability performance (K). In this work, a copper powder-fiber composite wick was fabricated by sintering of the copper powder and fiber mixture. Effects of the copper powder particle size, copper powder volume ratio, as well as the super-hydrophilic treatment were investigated, and the results indicate

Jet impingement heat transfer finds applications where a large heat flux is required between a fluid and a surface. Impinging jets can be implemented in Concentrating Solar Power (CSP) thermal receivers and bayonet tube heat exchangers. A simultaneous outlook on the heat transfer and total pressure loss (performance) characteristics of several jets impinging on a concave hemispherical surface are investigated

The performance evaluation of radiator with the application of a new coolant, water-based of various shape nanoparticles i.e., spherical (CuO), cylindrical (CNT), platelet (Graphene) and vol. concentrations based ternary hybrid nanofluid have been investigated theoretically. Impact of heat transfer rate and pressure drop along with exergetic analysis on vol. fraction of ternary hybrid nanofluid, coolant

A parametric study is proposed in this paper to examine heat dissipation rate and entropy generation of a forced convection in a horizontal pipe which is filled with high porous metallic foams. The study quantifies the effect of thermal conductivity and pore density on entropy generation when the pipe is fully filled with copper, aluminium and nickel metallic foams of 0.6 m length in the fluid flow

Tomato (Solanum lycopersicum) and brinjal (Solanum melongena) are food products that are frequently wasted in Indian markets as their shelf lives are only a few days. An indirect type solar dryer (ITSD) has been developed. It’s performance and drying kinetics of brinjal and tomato slices have been analyzed. The moisture content of tomato decreased from 15.667 to 0.803 kg/kg of dry basis (db) and that

Pulsating heat pipe (PHP) is a two-phase heat transfer device, and the start-up characteristics plays a crucial role in its practical application and stable operating performance. This paper introduced the start-up principle of PHP and reviewed the influences of the cross-sectional shape, the physical property parameters and the external field action (i.e., magnetic field, ultrasonic wave etc.) on

It is important to study the temperature stratification phenomenon in flash evaporation to well design the marine accumulator and some related industrial equipment. Therefore, a series of flash evaporation experiments with initial temperature of 65.0 °C ~ 84.4 °C and superheat degree of 5.0 °C ~ 30.0 °C are carried out to study the temperature variations at different water depths. Meanwhile, the functional

Experimental results showed that the effective thermal conductivity of silicon nanowire is smaller than the bulk thermal conductivity, while that of carbon nanotube (CNT) is usually much larger than its bulk counterpart. In order to resolve this paradox, a nonlocal heat conduction model for one-dimensional materials is proposed. This nonlocal model indicates that the different heat conduction boundary

Natural convection heat transfer from vertical 9 × 9 rod bundle in liquid sodium was numerically analyzed to optimize the thermal-hydraulic design for the bundle geometry with equilateral square and triangle arrays (ESA and ETA). Unsteady laminar three-dimensional fundamental equations of natural convection heat transfer caused by step heat flux were solved numerically until the solution reached a

Indonesia is country that owns large enough source of geothermal energy. One effort can be done by utilizing geothermal energy as source for electrical energy generation. To produce a source of electrical energy using ORC using water (H2O) as a working fluid. In this research ORC system uses Refrigerant R-141b as a work fluid for water experiment (H2O) used at Rankine cycle at general. There are 4

In this study, experimental investigations and exergy analysis on shell and helically coiled tube heat exchanger are carried out for free convection heat transfer. The measured data are totally optimised utilizing thermodynamics rules in which exergy study is performed to investigate the thermal performance of the helical system under different operating conditions. The experimental set-up of apparatus

The present work deals mainly with dehydration characteristics of onion slices. Microwave power levels of 100, 350, 550 and 750 W was practiced to dry onion slices with thicknesses of 2.5, 5, 7.5 and 10 mm. The results showed that moisture diffusivity and specific energy consumption of the process increased with both increasing microwave power and the samples thickness, and ranged from 0.82 × 10−8

This paper investigates the total freezing time of droplets on surfaces with various wettabilities with horizontal and inclined orientations. A two-dimensional Volume of Fluid (VOF) method was applied to capture the liquid-air interface, and an automatic localized grid treatment technique was applied to increase the accuracy, especially near the impact and spreading areas. The Kistler and Shikhumurzaev

Thermochemical heat storage materials for space heating applications such as, ZnSO4 offer high energy storage density, low cost and clean mean of long-term solar energy storage. Herein, we studied the ZnSO4 hydrated salt as potential heat storage material at low temperature and furthermore observed the impact of temperature and concentration on the dehydration/hydration process and enthalpy. The thermal

In the present study, a series of experiments are conducted to investigate the thermal performance of a copper made pulsating heat pipe consisting of uniform flow passages with the cross section of 2 mm × 2 mm. Test conditions cover two orientations (0° and 90°) and six different filling ratios (10%, 25%, 40%, 55%, 70% and 85%). The working fluid used in the experiments is methanol. Heat inputs are

For further understanding the coal spontaneous combustion in goaf, the dynamic evolution of the oxygen concentration field influenced by the condition of negative pressure of cross-cut were analyzed. Based on the on-site testing results, the range of the oxidation zone on the headentry and tailentry side is determined as 30 ~ 75 m and 15 ~ 65 m respectively. This paper adopts a new method called “fixed

Heat transfer, fluid flow characteristics and entropy generation of water-Al2O3 nanofluid for cylindrical heat sinks with helical minichannels that have secondary branches are investigated experimentally. The minichannels helix angles are 45, 60 and 90 degrees; the volume fraction of nanoparticles variation is 0.05% – 0.1%; the Reynolds number range is between 113 to 478. The effects of the helix angle

Latent heat storage units are considered as an effective solution for the mismatch problem between energy consumption and energy supply when utilizing solar energy. However, the low thermal conductivity of the current phase change materials (PCMs) is regarded as their main drawback. The present study used dispersing nanoparticles in PCM and installing longitudinal fins on the inner tube simultaneously

In this paper, an experimental study on the effect of the low aspect ratio of microchannel on the critical heat flux (CHF) during saturated flow boiling of water is presented. Multiple parallel silicon microchannels with different aspect ratios, hydraulic diameter, and number of channels in the range of 0.2–0.5, 154.0–184.8 μm, and 3–9 respectively are fabricated, and the experiments are performed

In this paper, the performance of a PVT (photovoltaic thermal) air collector with V-groove absorber in the air channel is theoretically and experimentally examined under different climate conditions of Ghaziabad city, India, in summer, June 2019. A low power brushless DC fan is fixed at the input of the air-channel to ensure the circulation of air through the V-groove. The energy balance equation is

Liquid jet impingement is used for cooling and cleaning in various industrial branches. The advantages of jet impingement include high heat and mass transport rates in the vicinity of the impingement point. Pulsating liquid jets impinging on horizontal substrates with a pulsation frequency around 100 Hz have been shown to increase the cooling efficiency in comparison to jets with continuous mass flow

The identification of the type of regime has an essential effect on the selection of sub-grid scale and discretization methods, regarding the accuracy and computational time. In order to investigate the role of sub-grid scale and time discretization method in a pool fire modeling by the Large Eddy Simulation (LES), three sub-grid scales Smagorinsky, one-equation and Wall-Adapting Local Eddy-Viscosity

Journal bearings are used in industrial equipment at high rotational speed. Normal and also fault operations of bearing increase the temperature of the bearing. Estimation of heat flux on the inner surface of the bearing and prediction of temperature of the bearing can prevent the damage to the bearing. In this research, these quantities are estimated in normal operation by an inverse method. The sequential

The motivation of the paper is an attempt to indicate the relationship between the selected Gas Tungsten Arc Welding (GTAW) technology and the parameters of the boundary conditions for the simulation of the heat treatment process of elements made of medium-carbon steel. The authors of the paper prepared and described a series of numerical simulations and experimental studies concerning this problem

The flow field and mass transfer phenomena on wavy walls are studied both experimentally and numerically for application to the pipe-wall thinning of nuclear power plant. The numerical simulations are carried out using four turbulence models and the results are compared with the velocity field on wavy planar wall measured by particle image velocimetry, and the mass transfer coefficient data on a pipe

Compared to traditional continuous jets, synthetic jets (jets with oscillatory flow such that the time-average velocity is zero) have specific advantages, such as lower power requirement, simpler structure and the ability to produce an unsteady turbulent flow that is known to be effective in augmenting heat transfer. This study presents experimental and computational results that document heat transfer

In this paper, the experimental analysis of two types of corrugated plate solar collector (CPSC) using water as working fluid has been done. Two similar designs and dimensions of CPSC but different materials of absorber plates have been investigated, the collector1 is copper and collector 2 is aluminium. The performance of energy, exergy and total heat loss coefficient of CPSC were analysed and compared

Laminar convective heat transfer and pressure drop characteristics of Al2O3-water nanofluid were experimentally investigated inside a horizontal Helical-Coil Tube (HCT) under constant heat flux boundary conditions for Dean numbers between 400 and 1600. The experiments have been performed using Al2O3-water nanofluid of three mass concentrations and heat fluxes at different flow rates. Thermal conductivity

In literature, most studies have only focused on sorption characteristics of quinoa grains. This study is one of the limited studies that deal with the sorption properties of quinoa with a thermodynamic approach. In the designed study, the equilibrium moisture content of whole quinoa grains determined by the static gravimetric method and ten different sorption models were applied for the description

The investigations involved a large water droplet deposited on the heating surface, the temperature of which was higher than the Leidenfrost point. The main element of the experimental setup was the heating cylinder with K-type shielded thermocouple located in its centre just below the surface. The measuring system was located on highly sensitive scales. The analysis of the droplet behaviour in time

This is an incompressible numerical study of the hydrodynamics and heat transfer characteristics of Taylor flow in vertical oil and gas pipelines under constant heat flux using the Volume-of-fluid (VOF) method in ANSYS Fluent, covering a wide range of Re(0.22 ≤ Re ≤ 800) and Ca(0.0075 ≤ Ca ≤ 0.35). Nusselt number (Nu) correlations were used to examine the heat transfer characteristics based on a set

This study involves an optimization procedure for the factors affecting the performance of the parallel connected vortex tube system using the Taguchi method. The effect of vortex tube inlet pressure, working fluid, nozzle material and nozzle number parameters on vortex tube performance were obtained as a percentage using experimental design and analysis. Experimental studies were carried out at inlet

An investigation was experimentally performed to explore the influence of geometrical parameters on the evaporative heat transfer coefficient and pressure drop of R-134a in dimpled tubes. The test sections were the counter-flow tube-in-tube heat exchanger, where the refrigerant was evaporated in the inner tube and hot water flows in the annulus. Seven dimpled tubes with various helical pitches (p)

Thermosyphon is an effective heat transfer device which is widely used all over the world for its ease of use, feasible with different environmental challenges. In this research article, the experimentation with different boiling point of working fluids water and R134a has been used in modified thermosyphon. The modified thermosyphon comprises of the cone frustum attached between the condenser and

Rubberwood (Hevea brasiliensis) is a major raw material used in furniture factories in southern Thailand. Proper kiln drying of the lumber plays a significant role on the efficient utilization of the final product. Overall quality-reducing defects in such a materials are inevitable, unless a correct and proper drying process is used. Therefore, the objective of the present study was to develop a three-dimensional

The binding force between water molecules and the solid skeleton of fibrous porous media, determined by the microscopic structure and chemical interactions, has a remarkable influence on the dehydration process. Therefore, the micropore structure is a key factor affecting the dewatering performance of fibrous porous media. In this paper, fibrous porous media is treated by ultrasound; then the micropore

Osmotic dehydration (OD) is a pre-treatment commonly used to incorporate solids and dehydrate fruits. In this study, the influence of mixed syrup (yacon and sucrose) concentration used in OD and drying air temperature on drying kinetics of banana osmotically dehydrated and characteristics of dried banana were evaluated. Yacon syrup (30°Brix) was produced and then sucrose was added, making mixed syrups

Environmental pollution caused by burning fossil fuels, global warming, the greenhouse effect, and other factors has changed the approach of science to the use renewable energies. The main objective of this paper is to study the effects of diverse inputs (solar radiation) and collector geometries and also heat transfer of the solar chimney power plants (SCPP) model on the thermal and efficiency of

Technological developments are continuously growing to improve the efficiency of thermal systems on the demand of present era. To get rid of the scientists and engineers from traditional heat transfer intensification methods and to miniaturize thermal transport devices, novel and innovative techniques are obligatory. In this whole drive, the effective tube geometries and efficient working fluids perform

The objective of this article was to describe the osmotic dehydration of cubic pieces of melon immersed in solutions of water and sucrose, using a three-dimensional solution of the diffusion equation in Cartesian coordinates, considering the resistance to mass flows on the surface. Three experiments were conducted at room temperature, with no continuous stirring, at the concentrations of 25, 45 and

When simulating a daily performance of a solar thermal powered adsorption refrigeration system, daily weather data (i.e. daily maximum and minimum ambient temperatures and daily total solar radiation) are normally used to simulate a 24-h refrigeration cycle. However, the simulation obtained in this way is not that accurate, due to which could not reflect real hourly processes during the daytime. In

Numerous industrial applications of falling film flows alongside its heat and mass transfer complexities appreciate some deep and detailed studies. In order to recognize the influences of film flow rate on the modality of heat transfer coefficient, the falling flow of R-245fa at saturation pressure of 123.8 kPa around the horizontal tube has been simulated at different Reynolds numbers of 357, 500

Fouling in heat exchangers can complicate the characterisation and interpretation of thermal effects because of ageing phenomena that occur within the deposited fouling layer. The prevailing process temperatures between the liquid bulk and heat-transferring surfaces create a large thermal conductivity distribution according to the position of the layer within the deposit. During the growth phase, an

Tower type grain dryers are widely used in corn drying process and are manufactured as cylindrical structures with a height of about 30 m. Grain is filled into the annular section between the perforated walls and dried with exhaust gas from the combustion chamber. In terms of drying quality and energy efficiency, high capacity drying systems need a reliable control system. In the current study, a laboratory

In this study, nanostructures were fabricated on sintered copper powders through alloying-dealloying method for investigating and analyzing drop penetration and wetting characteristics. Based on the high-speed video imaging, the kinetics of droplets immersing process were studied for multi-scale composite compact (MCC), featured with the microns for copper particle sizes and nanometers for the surface

The experimental study of the frictional pressure drop characteristics of flow boiling heat transfer of CO2 in a horizontal minichannel with an inner diameter of Φ1.5 mm was carried out. Experimental conditions: heat flux (7.5 ~ 30 kW•m−2), mass flow rate (50 ~ 600 kg•m−2•s−1), saturation temperature (−40 ~ 0 °C), vapor quality (0 ~ 1). The comparison between the experimental results and theoretical

The solidification dynamics of cylindrical encapsulated PCM have been analyzed under convective boundary conditions that relate to thermal energy storage systems. A three dimensional, transient CFD model has been solved for examinations. Besides the widely used conduction model of solidification, in this study, the effect of natural convection within the liquid layer has been considered in the numerical

In this study, the cooling capacity and the pressure drop variation in an automobile radiator using nanofluid instead of water with antifreeze that are investigated experimentally. The nanofluid consisted of 50% Ethylene Glycol–Water mixture including Al2O3 nanoparticles with 0.5% volumetric concentration was used as coolant. In all experiments, the inlet temperature of the cooling fluid into the radiator

Thermal contact conductance (TCC) plays a vital role in improving the performance and the service life the electronic devices. As, the solid conduction paths through which the heat as to be dissipated includes multiple metal-metal and metal-dielectric contacts, which offers significant resistance to the rate of heat transfer. There exists a strong need for the estimation of TCC at the interface of

The effect of gravity on the dynamics of flow boiling channels is studied using linear and non-linear stability analysis tools. The developed tools are used to predict experimental results showing good agreement. The linear stability analysis shows that gravity enhances the density wave instability mechanism, enlarging the linear unstable region. Non-linear effects are then investigated by using Hopf

Our aim is to determine the more significant parameters acting on the water vapour condensation in a partly closed structure, submitted to external constraints (temperature and humidity). These constraints locally lead to condensation of the water vapour, initially contained in the air of the volume and/or on the walls. Previously we have presented the results obtained in two papers. In the first one

As far as design safety and operation of heat exchangers with a horizontal flow are concerned, it is necessary to study local heat transfer coefficient, boiling pressure drop, and critical heat flux for flow in a horizontal tube. In the present experimental work, local axial distribution of heat transfer coefficient, two-phase pressure drop, and critical heat flux for the flow boiling in a horizontal

The gas-phase mass transfer coefficient is one of the significant parameter for the determination of mass transfer in absorption columns. A novel correlation was obtained for the calculation of the gas phase mass transfer coefficient in the current research study based on the theoretical investigation and experimental data. Buckingham pi-theorem was utilized to develop an overall dimensionless correlation

In this paper, a new composite support made of steel and polymer is proposed for the internal supports of mobile cryogenic vessels. Multilayered design of the steel part in the presented support controls the heat transfer through this part by adding more thermal contact resistance (TCR) to the heat flow path. An analytical model is developed to calculate TCR between layers of the steel part at the

In this paper, the experimental study of heat transfer during condensation of freons R22 and R407С in a plain smooth tube with 17 mm inner diameter was carried out at saturated condensing temperature 40 °C, while mass velocity ranged between 6 and 57 kg/(m2s) and vapour quality changed from 0.23 to 0.95. The unique measurements of circumferential heat fluxes and heat transfer coefficients were performed

Nucleate boiling is an important part of the pool boiling phenomenon which occurs in various processes involving heat transfer, such as, steam production, chemical processes, etc. The inclination of the heated surface, where bubbles nucleates, significantly affects the bubble growth dynamics as well as the heat transfer rate from the microlayer underneath the bubble during the nucleate boiling. In

Film cooling performance of a novel double jet configuration is numerically analysed. The proposed scheme has a primary compound angle hole along with a secondary hole compounded in the laterally opposite direction. The primary hole is provided with a trench at the coolant hole exit. Numerical analysis is performed using RANS equations along with standard k-ω turbulence model. The numerical scheme