Constant Wall Temperature Conditions Research Articles

Performance analysis and optimization of the Gyroid-type triply periodic minimal surface heat sink incorporated with fin structures

The Triply Periodic Minimal Surface (TPMS) structures demonstrate substantial value and development potential in applications and research concerning heat sinks and heat exchangers. To further enhance the convective heat transfer performance of TPMS, this study proposes a novel method of incorporating fin structures into TPMS. This method is applicable to various types of TPMS, and the new structure constructed using this method is termed “TPMS with Fin Structures (TFS).” Subsequently, a TFS-Gyroid heat sink based on the Gyroid-type TPMS was constructed. This study presents a calculation method for the fin height in TFS-Gyroid (HTFS-Gyroid). Numerical simulation methods were employed to investigate the influence and mechanism of HTFS-Gyroid on the convective heat transfer performance and flow resistance of the TFS-Gyroid heat sink model, with air as the working fluid and under constant wall temperature (100 °C) conditions. The results indicate that within the flow range of 24–120 L/min, as HTFS-Gyroid increases from 0 to 1.6 mm, the average surface convective heat transfer coefficient (h̅) of the TFS-Gyroid heat sink model increases by 27.4 %-34.6 %, and the inlet–outlet pressure drop (ΔP) increases by 42.5–632.8 Pa. As HTFS-Gyroid increases, the PEC of the TFS-Gyroid heat sink model gradually decreases, whereas j/f gradually increases. The primary mechanisms by which the fin structures enhance the convective heat transfer performance of the TFS-Gyroid heat sink are: 1) increased heat exchange area, 2) the fin structures induce a large number of longitudinal vortices and secondary flows within the flow channels, and 3) the formation of “Fins Occupying the Perforated Structure (FOPS)” within the flow channels.

Flow and Heat Transfer Characteristics in the Entry and Stabilized Flow Regions of a Circular Channel Rotating About a Parallel Axis

Abstract Cooling of heavy-duty electrical machines such as generators and motors is crucial for the smooth operations without thermal runaway. A commonly employed technique for the cooling of rotors in these machines is to place channels at different radial locations for the continuous passage of coolant. These channels are therefore rotating about a parallel axis, and the rotation-induced forces alter the flow and thermal behavior of the coolant compared to stationary channels. The present study reports a detailed numerical investigation on a long circular channel rotating about a parallel axis. The objective is to analyze the flow, heat transfer, and rotation-induced forces (Coriolis and centrifugal forces) in the entry region as well as in the region where flow is stable (the term ‘stable’ is used rather than ‘developed’ due to the presence of secondary flows in this region). The rotating channel was subjected to constant wall heat flux and constant wall temperature conditions at different Rotation numbers of 0, 0.15, 0.4, and 0.6. The Coriolis force is observed to be strong enough in the entry region to influence the flow. In the “stable flow” region, the centrifugal force becomes more dominant and forms counter-rotating secondary vortex pair, which causes circumferential variation in the Nusselt number. The flow and heat transfer characteristics for constant wall heat flux and wall temperature boundaries are the same for rotation conditions with similar values of rotational Grashof number. A correlation is presented for the circumferential variation of the Nusselt number in the stable flow region.

Effects of vibrational flow on nanofluid flow behavior under different temperature boundary conditions

A comparative study was conducted using a well-validated computational fluid dynamics (CFD) model to investigate the effects on heat transfer. The study focused on forced convection internal flow of both base fluid and nanofluid, subjecting them to different boundary conditions. Vibration was applied in the transverse direction to the flow. The simulations were performed with varying Reynolds numbers, volume fractions, vibration frequencies, and amplitudes. In order to improve the predictive capabilities of the computational fluid dynamics (CFD) model for single-phase flow systems, rheological properties dependent on temperature were incorporated. The introduction of transverse vibrations swiftly disrupted the thermal boundary layer, resulting in an axial temperature increase for low Reynolds number flows. Consequently, under constant wall temperature conditions, this led to heightened heat transfer rates. The observed enhancement in heat transfer rate, achieved through variations in volume fraction and particle diameter, aligned with typical behavior exhibited by nanofluids under steady-state flow. However, under vibrational conditions, the heat transfer enhancement surpassed that of the pure liquid significantly. As frequency levels rose, the impact of vibrations diminished, while changes in amplitude exerted a more pronounced influence. The most substantial increase, approximately 540%, was witnessed under vibrational flow conditions compared to steady-state flow. The ratio of the heat transfer coefficient was about 28% higher when the flow was subjected to uniform heat flux but under unsteady-state conditions. However, there was not much growth in the outlet temperature observed.

Numerical study of functional parameters of compact heat exchanger with the corrugated wall in steady state

Compact heat exchangers have several benefits over other types of heat exchangers, including compactness, a high surface area to volume ratio, and a low-temperature differential. They are frequently employed in the heat integrating process. Herein, a compact heat exchanger is simulated in a steady state using the AnsysFluent 17.2 software pack. The flow regime is laminar and water enters the exchanger at a temperature of 298.15 K, assuming a constant wall temperature condition. This study examines the effects of wall wave formation on fluid flow and heat transfer characteristics. The two parameters, wave altitude, and wave angle, are verified and the resultant corrugation is fitted as a sinusoidal function. As the wave height factor increases, the results show that the temperature and velocity values in the solution field climb. More than 4.5% more has been added to the highest temperature value. It is also shown that the velocity values rise with the wave angle coefficient. The greatest rise is 50%. The Performance Ratio is also examined in this study. The findings show that the angle coefficient of 0.5π and π and the altitude coefficient of 0.2 provide values for the Performance Ratio that are higher than the unit.

Temporal numerical analysis of beeswax PCM melting in a cube geometry subjected to a constant wall temperature condition

The ability of phase change materials (PCM) to store thermal energy has gained wide application area, like battery thermal management, solar water desalination and many other. The melting process of beeswax phase change material within the cube geometry with constant wall temperature (65 °C) boundary condition has been investigated using solidification and melting model. The fluid flow and heat transfer governing equations are solved using second order finite volume scheme. A PRESTO algorithm is applied for pressure-velocity coupling. The convergence criteria of 10−10 have been selected for energy equation, while 10−8 is selected for both momentum and continuity equations. The results like percentage variation along length-height and height-width plane for transient liquid fraction and temperature has been plotted, along with velocity streamlines within the cube geometry. From the obtained results it is concluded that the melting fraction and temperature of beeswax PCM is different in different planes and the major factors which affect the complete melting process is wall temperature, and the geometry. A difference of more than 0.1 °C in temperature has been recorded between mid-length-height and height-width plane while a difference of more than 2% in liquid fraction of PCM is observed. Even the uniformity of temperature and liquid fraction is notably influenced and vary along length, height, and width of cube geometry. Thus, it is concluded that melting process of PCM may affect the ability to store and release the heat energy which further affect the performance parameters of applied physical system.

Low-Reynolds-number turbulent forced-convection flow over graded baffle plates

The thermo-hydraulic behaviors of turbulent forced-convection heat transfer flow over a rectangular cross section baffled channel are numerically examined in various graded baffle plate ratio configurations ‘GBR = 0.10, 0.11, 0.12, 0.13, 0.14, and 0.15) at different Reynolds numbers, ranging from 12,000 to 32,000. The governing equations that describe the flow are integrated by the finite volumes method, in two dimensions, employing the Commercial CFD software FLUENT 6.3 with low-Reynolds-number k-E model to describe the turbulence. The velocity and pressure terms of momentum equations are solved with SIMPLE-algorithm. In particular, axial velocity, turbulence intensity, pressure, and temperature fields, average Nusselt number and friction loss are obtained. The numerical runs are carried out for different values of Reynolds numbers and graded baffle ratios at constant wall temperature condition along the top and bottom walls. Results were compared with available experimental data from the literature and good agreement is obtained.

Numerical study on heat transfer characteristics of molten salt in a flat tube with circular helical wire

The combination of a new type of irregular-shaped helical wire and flat tube is used to further enhance heat transfer of molten salt for the first time due to the demands of efficient utilization of molten salt. The thermo-hydraulic performance of turbulent flow in a flat tube with irregular-shaped helical wire under constant wall temperature condition is investigated using Fluent software. The effects of helical pitch, wire diameter, gap width between the tube wall and helical wire, different fluids and inlet Reynolds number ranging from 1500 to 8500 are evaluated. It is found that adding irregular-shaped helical wire insert in flat tube can reduce greatly the lengths of flow and thermal entrance regions. The maximum heat transfer performance of flat tube with irregular-shaped helical wire is 400% that of smooth flat tube. The heat transfer performance increases with the wire diameter and decreases with the gap width and helical pitch. The maximum thermal performance factor with a value of 1.72 is observed based on a constant pumping power. Besides, the heat transfer performance of flat tube with irregular-shaped helical wire is 24.0%-40.2% larger than that of circular pipe with helical wire at low Reynolds number.

Particle-resolved simulations for nanofluid thermal enhancement in channel flows

Nanofluids have been studied extensively for improved heat transfer performances in various thermal systems. In this article, we adopt the particle-resolved method to study the thermal enhancement of nanofluids in channel flows under constant wall temperature (CWT) and constant heat flux (CHF) conditions. The smoothed profile method is employed to describe the nanoparticles suspending in the base fluid and the lattice Boltzmann method is utilized to solve the flow and temperature fields. Unlike the continuum representation of nanofluids, this particle-resolved approach can incorporate the thermophysical properties of the base fluid and nanoparticles directly in simulation, and flow and temperature distributions around nanoparticles are available. Our simulations reveal detailed information on the nanoparticle influence on the wall thermal distributions, and illustrate the enhancement mechanism for heat transfer between the boundary wall and fluid flow: The nanoparticles near the wall increase the local heat flux under CWT and decreases the local wall temperature under CHF condition. The heat transfer coefficient is utilized to characterize the thermal performance for nanofluids, and it increases 6–16% for the nanofluid systems considered in our simulations. The effects of key system parameters, such as the nanoparticle volume fraction, thermal conductivity, and Reynolds number, are also investigated. Our results show that, for both CWT and CHF systems, the particle volume fraction and thermal conductivity can both increase the heat transfer coefficient; however, the particle conductivity effect becomes less significant or even negligible when it is greatly larger than the base fluid conductivity. For the limited range and relatively low values of Reynolds numbers considered in this work, it appears that the Reynolds number has no obvious influence on the system thermal performance. These finding could be beneficial for a better understanding of the complexity of nanofluid systems and for future nanofluid development and applications.

Experimental Analysis of a Bayonet Tube at Constant Wall Temperature Conditions Under Laminar, Transition, and Turbulent Flow

Abstract An experiment was carried out on a bayonet tube that was kept at a constant temperature using condensing steam. In contrast, cold water was permitted to enter the central tube and discharge via an annular portion. The water flow rate was varied, covering laminar, transition, and turbulent regimes. The inner part of the bayonet tube is CPVC (chlorinated polyvinyl chloride, k = 0.136 W · m−1 · K−1), which reduces short-circuit heat transfer across the tube. Temperatures were recorded at different points in the tube. From the results of experiments on total heat transfer and short-circuit heat transfer, the Nusselt number can be calculated. The pressure drop across a bayonet tube determined the friction factor. In examining a range of Reynolds numbers, Effectiveness and figure of merit have been resolved. It has been observed that as the Reynolds number increases, the Nusselt number increases while the friction factor decreases. Both Effectiveness and Figure of Merit decrease with the addition of the Reynolds number, and it is observed that the maximum effective value is 0.86 for a 75 Reynolds number, which is suitable for bayonet solar collectors, and the minimum effective value is 0.2 for an 8062 Reynolds number, which is suitable for bayonet heat exchangers. It serves as reference work for bayonet tubes for designing a parabolic solar collector and heat exchanger.

Heat transfer enhancement of nanofluid flow at the entry region of microtubes

A numerical investigation on laminar nanofluid flow and convective heat transfer at the entry region of microtubes subjected to constant wall temperature and constant heat flux boundary conditions has been carried out employing a multiphase Eulerian–Lagrangian method. The impacts of the Peclet number (175 ≤ Pe ≤ 3500), nanoparticle volume fraction (0.1 ≤ φ ≤ 1.0%), and nanoparticle diameter (40 ≤ dp ≤ 130 nm) on thermal characteristics of Al2O3-water nanofluid flow through a microtube are analyzed in detail. The results indicate that the influence of the Reynolds number on apparent friction factor and the impact of the axial heat conduction on the Nusselt number for the nanofluids have to take into account in the entry region. Compared with the influences of particle concentration and particle size, the entrance effect dominates pressure drop and thermal performance of the nanofluids near the entrance of the channel. As the dimensionless axial distance increases, the entrance effect is weakened, and the influences of particle concentration and particle size are gradually reflected in flow and heat transfer results. Besides, the particle effects on thermal performance of the nanofluids are earlier and higher than that on flow resistance. Performance evaluation demonstrates that the nanofluids in the entrance region have not only heat transfer enhancement but also a good economy. When Pe = 175, the PEC of Al2O3-water nanofluids with particle concentrations of 0.1, 0.2, 0.5, and 1% increased by 104.0, 103.1, 113.8, and 128.5% under constant heat flux condition, respectively, at the dimensionless axial distance x* = 0.01 compared with deionized water; the PEC improved by 74.6, 77.2, 85.6, and 102.5% under constant wall temperature condition compared with deionized water, respectively.

Multi-objective optimization of 3D micro-fins using NSGA-II

Because of the great potential for optimization of micro-fin surfaces (< 0.5 mm tall) and the lack of any optimization work encompassing three-dimensional geometries on heat exchanger surfaces, this paper proposes a robust methodology to solve the multi-objective optimization problem with a numerical model and thereby determine the flow physics that characterize the optimal geometries. The micro-fin design variables are considered as micro-fin height, angle, thickness, pitch, length of discontinuity, and number of discontinuities per micro-fin pitch. To reduce computational time, a channel with two-sided periodic domains is presented. A parallelizable numerical model is developed based on Reynolds average Naiver-Stokes equations and a realistic k-ɛ model. The simulation procedure solves convective heat transfer and turbulent flow over micro-fins and solves heat transfer for solid conduction using a constant wall temperature condition to maintain robustness for geometries that do not yield unity fin efficiencies. This study provides a robust methodology to integrate the numerical model into a multi-objective optimization algorithm named non-dominated sorting genetic algorithm II to generate the best trade-off solutions between enhancement of Nusselt number and Fanning friction factor of a micro-fin surface to a smooth surface at two Reynold numbers (Re) of 25,000 and 49,000. This study presents a unique intersection of the drag reduction approach and heat transfer enhancement by finding unique operating geometries. For example, a particular optimal design geometry at Re = 49,000 reduced drag by 8% but was also beneficial to heat transfer increasing by 21% compared to a smooth surface. The best micro-fin surface of this study at Re = 49,000 enhanced the efficiency index by 18% compared to the highest reported efficiency index for micro-fin tubes.

Novel thermosyphon-assisted setup for determining heat exchanger thermal characteristics

To be used in the market, thermal and friction characteristics of newly launched heat exchangers must be acknowledged, usually by experimental methods. Steady-state Kays and London is considered the classical experimental technique. In this setup, one of the heat exchanger streams is usually vapor, to provide controlled known heat transfer and temperature conditions, while the other stream is subjected to different flow rates, for the determination of the equipment thermal and pressure drop behaviors. Large expensive industrial boilers are usually used, resulting in difficulties in stabilizing and controlling vapor temperatures. In the present work, a new experimental setup, based on the above-mentioned technique, is proposed for determining the heat transfer characteristics of compact heat exchangers. The boiler vapor flow is substituted by the working fluid (water in vapor state) of a two-phase thermosyphon. Being smaller and much more flexible, this technology allows for easy control of the vapor temperature, while providing uniform temperature distribution along one of the heat exchanger streams, which is difficult to obtain with the classical procedure. In the proposed apparatus, the “known side” of the heat exchanger takes the role of the condenser of the thermosyphon. Two well-known heat exchanger cores, composed by circular and square cross section channels, were used to validate the proposed arrangement, considering the ranges: 2200 < Re < 8000 and 850 < Re < 2800, respectively. The wall temperatures were tested in the range 120 °C to 220 °C with a precision of ± 0.5 °C in steady-state. In addition, the resulting Nusselt number (Nu) and the Fanning friction factor (f) data were compared with consolidate literature correlations showing an average discrepancy of 15% for both geometries and parameters. Therefore, the use of thermosyphons results in smaller, simpler and more precise test benches to be used for the evaluation of heat exchangers, as it provides the desired constant wall temperature conditions for the characterization of core geometries, substituting, with advantages, the use of large and expensive steam boilers.

Numerical analysis of convective heat transfer on straight finned tube with different nano fluids

The major idea of this effort is to study and analyse heat transfer through a straight finned duct with different nanofluids. Dynamics and simulations for fluid flow at the start of fully developed laminar flow with nanofluids in a circular duct with and without fins under constant wall temperature conditions are performed by using fluent commercial software. Heat transfer behaviours of the duct are investigated for constant wall temperature conditions for oxides of nanofluid. The thermal properties of nanofluid are considered from the literature. Commercial software ANSYS 2018 was used to compute the velocity and thermal analysis between the inlet and outlet of the tube. The finite volume method will be used to discretize the whole domain in quadratic elements considered with the turbulence model. Turbulence differential equations system coupled with the heat convection. The flow and pressure, the temperature in the exit will be calculated as a function of initial conditions in the entrance of the duct. The fluid properties such as conductivity and viscosity of the base fluid are taken as temperature independent. The enhancement in heat transfer rate are presented graphically with the effect of effects of nanoparticle volume fraction, nanoparticle size.

Fluid flow and convective heat transfer in a rotating rectangular microchannel with various aspect ratios

The features of flow fluid and convective heat transfer have been investigated numerically in a rotating rectangular U-shaped microchannel for various aspect ratios (AR). Pure water is used as working fluid and 3D steady simulations are performed for Reynolds number of 400. The effects of aspect ratio (AR = 0.25–4), slip/no-slip conditions, rotational speeds in the range of 0–300 rad/s on the velocity profiles/contours, heat transfer, pressure drop, Nusselt number, and thermal performance coefficient are studied. The results show that an increase in AR (for AR>1) or a decrease in AR (for AR<1) provided an increase in pressure drop and heat transfer. Besides, contrary to hydrophilic microchannel, the heat transfer and pressure drop decrease in microchannel with the hydrophobic surfaces for all ARs considered. In addition, the thermal performance coefficient (E) is used as a balance between heat transfer augmentation and the power consumed. It is found that the E is higher for microchannel with hydrophobic surface than that of with hydrophilic one for all ARs examined. Moreover, the rotating microchannel is more efficient in respect to heat transfer enhancement than that of the stationary case, especially at AR = 1. Moreover, the results for two thermal boundary conditions of constant heat transfer and constant wall temperature conditions are compared at AR = 1 and it is found that the total Nusselt number is higher for constant wall temperature case than that of constant heat flux case in rotating microchannel while it is contrary in stationary one.

Numerical study on the nanofluid flows and temperature behaviors in the spirally coiled tubes with helical ribs

The nanofluids heat transfer and flow behaviors in the spirally coiled tube with and without helical ribs are simulated using the Eulerian two-phase turbulent model. A model used in the present study is 8.5 mm diameter copper tube, bending into the spirally coiled tube with and without helical ribs under constant wall temperature conditions. As flowing in the spirally coiled tube, the secondary flow is induced by the centrifugal force. In contrast, the swirling flow is caused by the pipe's helical ribs, which have significant effects on the Brownian motion of nanoparticles suspending the base fluid and then results in higher heat transfer enhancement. It can be found that the helical rib configurations have a significant effect on the velocity and temperature contours. The Nusselt number from the spirally coiled tube with helical ribs is 12.45% higher than those without helical ribs. However, due to more flow complexity and roughness augmentation, the pressure drop across the test section also increases. Besides, adding 0.05% nanoparticles by volume to water enhances the Nusselt number by 8.21%—also, the overall enhancement in heat transfer.

Heat Transfer and Entropy Generation Through Finned Tubeess and Behavioral Analysis of Employees using Statistical and Correlation Methods

The study deals with the heat transfer through helical finned tube. The helical finned tube is taken in order to increase the heat transfer rate. Through the helical finned tube, the heat transfer and entropy generation are evaluated numerically on the basis of constant heat flux and constant wall temperature conditions. In case of constant wall temperature, optimised condition for fin height is obtained. At fin height of 0.002538m the heat transfer is maximum and entropy generation is neither minimum and nor maximum and it lies in between the maximum and minimum value. In case of constant heat flux conditions the entropy generation is continuously decreasing with fin height. Since, the values of heat transfer and entropy generation are calculated for helical finned tube the results obtained are fairly good, as the entropy is not increasing, using helical finned tube we can increase the heat transfer to a larger extent. The report also deals with the heat transfer through external fins, which is used in radiator. The heat transfer and entropy generation of automotive radiator have been numerically evaluated for different fin configurations (louvered, plain, and wavy fin).

Heat Transfer and Entropy Generation Through Finned Tube

The study deals with the heat transfer through helical finned tube. The helical finned tube is taken in order to increase the heat transfer rate. Through the helical finned tube, the heat transfer and entropy generation are evaluated numerically on the basis of constant heat flux and constant wall temperature conditions. In case of constant wall temperature, optimised condition for fin height is obtained. At fin height of 0.002538m the heat transfer is maximum and entropy generation is neither minimum and nor maximum and it lies in between the maximum and minimum value. In case of constant heat flux conditions the entropy generation is continuously decreasing with fin height. Since, the values of heat transfer and entropy generation are calculated for helical finned tube the results obtained are fairly good, as the entropy is not increasing, using helical finned tube we can increase the heat transfer to a larger extent. The report also deals with the heat transfer through external fins, which is used in radiator. The heat transfer and entropy generation of automotive radiator have been numerically evaluated for different fin configurations (louvered, plain, and wavy fin).

Investigation on thermophysical properties, convective heat transfer and performance evaluation of ultrasonically synthesized Ag-doped TiO2 hybrid nanoparticles based highly stable nanofluid in a minichannel

Ag-doped TiO2 hybrid nanoparticles have been synthesized by ultrasonic-assisted method for nanofluid application for heat transfer in minichannel heat exchanger at constant wall temperature condition. Prepared nanoparticles were dispersed in water by ultrasonication to form an extremely stable nanofluid. Thermal conductivity of the nanofluid was found to be 1.84 W/mK at 45 ℃ for nanofluid concentration of 0.25 vol%. The overall heat transfer coefficient increased from 1211.71 to 2727.38 W/m2K as the nanofluid concentration increased form 0.01 vol% to 0.1 vol% at Reynolds number of 3480 ± 3. A new correlation for Nusselt number has been proposed. The pressure drop and friction factor of the nanofluids were also advantageously lesser than that of water. The overall performance of the Ag-doped TiO2 hybrid nanoparticles based nanofluid was assessed by comparing the heat transfer with the pumping power and by determining the entropy generation and thus the Bejan number.

OVERLAPPING MULTI-DOMAIN SPECTRAL METHOD FOR NON-DARCIAN MIXED CONVECTION CHEMICALLY REACTING FLOW OF MICROPOLAR FLUID OVER A FLAT PLATE IN A POROUS MEDIA

An efficient overlapping multi-domain spectral method is presented and used in the analysis of a two-dimensional steady laminar MHD mixed convection flow, heat and mass transfer over a vertical flat plate embedded in a porous medium. The effect of chemical reaction, thermal radiation, heat source/sink and other parameters influencing the flow has been analyzed by imposing magnetic force transverse to the plate in a non-Darcy porous medium with constant wall temperature and concentration conditions. The flow equations are expressed in dimensionless form and solved using overlapping multidomain bivariate spectral local linearization method (OMD-BSLLM). An analysis of the convergence and accuracy of the OMD-BSLLM is given using error norms and residual errors. Comparisons with previously published work for special cases of the problem are performed and excellent concurrence is found; hence reliable results are being presented. The influence of certain parameters on the fluid properties and flow characteristics is analyzed. The skin friction, heat and mass transfer coefficients are presented for the concentrated flow and the turbulent boundary layer flow. The flow characteristics are found to be smaller for turbulent boundary layer flows than concentrated particle flows. This type of flow has an application in catalytic and chromatographic reactions, packed absorption and distillation towers.

Experimental Investigations on the Influence of Coil Arrangement on Melting/Solidification Processes

The latent heat thermal energy storage units are very popular because of their high energy density and almost close to constant temperature during the charging/discharging. In the present study has been proposed new shell-and-coil geometry with a shifted coil position to enhance the performance of phase change thermal magazine. The experimental investigations have been performed both for the melting and solidification process of coconut oil for constant wall temperature conditions. The experiments have been carried out for cylindrical as well as coil shape geometry of the TES unit. In the case of annular TES, the copper tube with outer diameter d = 10 mm and total length equal to 165 mm were used (4). In the case of shell-and-coil TES the coil has been also made of a copper tube but with an outer diameter d = 6 mm. The total length of the tube was 460 mm. However, the length of the tube element that has been used in the process of bending the coil had a total length equal to 360 mm. The rest of the tube was straight. The coil pitch was 15 mm and the outer coil diameter was 26 mm. The experiments have been conducted for the coil position at the top and the bottom of the tank. The results showed the influence of heat transfer geometry for phase change efficiency. The article presents the thermal characteristic of melting and solidification phenomena as well as their visual analysis. A significant impact of heat transfer geometry at the shape of the melting and solidification profile. The optimal performance has been achieved for shell-and-coil TES with a coil arranged at the top of the tank.