Amount Of Heat Transfer Research Articles

Study of the interaction between a cavitation bubble and nearby biomimetic gas-entrapping microtextured surfaces and the potential damage effects on the wall using the compressible multiphases volume of fluid model

In the study, a compressible multiphase volume of fluid considering the phase change and thermal effect is presented, the interaction between a cavitation bubble and nearby biomimetic gas-entrapping microtextured surfaces is investigated using this model, and the potential damage effects on the wall are carefully analyzed. Based on this interaction, the standoff distance is classified into three types. For γ > 2.0, the cavitation bubble remains spherical during the expansion phase because it is not influenced by the entrapped gas cavities. However, during the contraction phase, it generates a jet directed away from the wall. For 1.0 < γ < 2.0, the cavitation bubble is affected by the cavities, causing it to lose its spherical shape during the expansion phase. For 0 < γ < 1.0, the cavitation bubble is close to the gas cavities, mixing with the gas cavities during the expansion phase. Two processes are identified as the main reasons for the potential damage to the wall. Furthermore, compared to a flat wall surface, the peak of the pressure impulse on the wall with entrapping gas cavities decreases by 33%, and the peak of the heat transfer quantity decreases by 59%, significantly reducing the damage to the wall.

Performance optimization of a printed circuit heat exchanger for the recuperated gas turbine

To further improve the thermal efficiency of gas turbines, the recuperator needs to be employed and the printed circuit heat exchanger with airfoil fins meets the recuperator's requirements of high heat transfer capacity, low flow resistance, and high reliability. However, the effect of airfoil fin pitches is not clear and the structure optimization method should be developed. In this study, the heat transfer quantity and pressure drop per length of the flue gas in the airfoil channels are numerically investigated under different Reynolds numbers and airfoil fin pitches. The results show that the effect of the airfoil transverse pitch has a great effect on the performance of the flue gas and the heat transfer quantity is increased by 82.39 %–96.08 % when the transverse pitch is decreased from 6.0 mm to 1.2 mm. At the same time, the pressure drop per length is increased to 189.39–842.47 Pa/m. The heat transfer performance is varied not obviously when the airfoil longitudinal pitch is varied from 4 mm to 15 mm. Based on the numerical data, the multiple-objective genetic algorithm combined with the backpropagation neural network is proposed for the performance predictions and optimizations. The corresponding Pareto front is obtained and the technique for order preference by similarity to the ideal solution method is employed to obtain the optimal point. Under the current conditions, the heat transfer quantity of the optimal point is 521.25 kW/m2, which is decreased by 34.5 % compared to the highest value, and the pressure drop per length of the optimal point is 108.45 Pa/m, which is decreased by 85.2 % compared to the highest value.

Experimental study on convection heat transfer properties in rough-walled fractures of granite: The effect of fracture roughness

The fracture-dominated convection heat transfer behavior is commonly involved in the development, utilization and storage of thermal energy in fractured rock engineering. An experimental system assembled by a peristaltic pump drive, a liquid preheater and an electric blast drying oven is developed to quantify the effect of fracture roughness on the convection heat transfer characteristics. The overall heat transfer coefficient (OHTC) and the amount of heat transfer quantity from six fracture samples with different inlet temperatures and flow rates are calculated by the data acquisition at five observation points. In general, the average convective heat transfer efficiency between water and rock decreases gradually with time, and then enters a stage of thermal equilibrium while the temperatures at the five observation points become constant. The increasing flow rate can lead to the gradual increase of the OHTC and the slowdown of its growth rate. The OHTC is negatively correlated with the inlet temperature. With the increase of fracture surface roughness, the dominant flow effect is significantly enhanced, which leads to the weakening of heat transfer characteristics and the gradual reduction of OHTC. Finally, the heat transfer quantity decreases with the increase of roughness, and exists an inflection point with the flow rate.

Investigation of refrigerant-dependency on the performance of conical double helix tube Joule-Thomson cryocooler

Miniature Joule-Thomson (J-T) cryocoolers are widely used in the cryogenic field due to their advantages of small size, and fast cooling. Selecting the appropriate refrigerant is a crucial task in designing a J-T cryocooler, as it significantly affects its cooling performance. To study the refrigerant-dependent influencing on the cryocooler's performance, an improved one-dimensional model for a conical double layer J-T cryocooler was developed. The model has been verified to have higher accuracy, faster computing speed, and applicability across a wider range of operating conditions. Nitrogen and argon, commonly used refrigerants with similar saturation temperatures, were investigated. Both simulation and experimental results indicate that argon exhibits a faster cooling rate, while nitrogen achieves a lower cooling temperature under the working conditions. The numerical studies suggest that argon's higher density and lower J-T coefficient contribute to its faster cooling characteristic, resulting in a higher heat transfer quantity in the double layer heat exchanger. However, increasing the vessel pressure can quickly reduce the difference in cooling rates between nitrogen and argon, and it may even make nitrogen more optimal. Moreover, it was observed that a significant portion of the cooling capacity is utilized to cool the cryocooler itself for both nitrogen and argon.

Are Local Heat Transfer Quantities Useful for Predicting the Working Behavior of Different Pulsating Heat Pipe Layouts? A Comparative Study

Despite a continuous effort devoted by the scientific community, a large-scale employment of Pulsating Heat Pipes for thermal management applications is still nowadays undermined by the low reliability of such heat transfer systems. The main reason underlying this critical issue is linked to the strongly chaotic thermofluidic behavior of these devices, which prevents a robust prediction of their working behavior for different geometries and operating conditions, consequently hampering proper industrial design. The present work proposes to thoroughly compare data referring to previous infrared investigations on different Pulsating Heat Pipe layouts, which have focused on the estimation of heat fluxes locally exchanged at the wall–fluid interfaces. The aim is to understand the beneficial contribution of local heat transfer quantities in the prediction of the complex physics underlying such heat transfer systems. The results have highlighted that, regardless of the considered geometry and working conditions, wall-to-fluid heat fluxes are able to provide useful quantities to be employed, to some extent, to generalize Pulsating Heat Pipe operation and to improve their existing numerical models.

Theoretical calculation and experimental analysis on humidification performance of high-performance water-absorbing porous fiber plates

In order to improve the indoor relative humidity in winter, a high-performance water-absorbing porous fiber plate was introduced in this paper, which absorbed water and infiltrated through capillary action, and an experimental system with porous plates arranged in parallel as humidifying elements was designed and constructed to explore the humidifying performance of porous plates and to expand its application field. The experimental results showed that the humidification effect of porous plates was excellent. At a relative humidity of 15 %, mainstream air velocity of 3.5 m/s, and air temperature of 45 °C, the maximum humidification capacity of the system reached 266.4 g/h. The humidification capacity was proportional to the air temperature and mainstream air velocity, and inversely proportional to the relative humidity of the air. The mainstream air velocity increased by 0.5 m/s, the humidification capacity increased by about 20 g/h. The change trend of humidification capacity and heat transfer quantity calculated through the criterion correlation was consistent with the measured values, and the relative errors between the theoretical and experimental values for most of the conditions were within 20 %. One of the reasons for the errors might be that the mainstream air velocity in the gaps between the porous plates was greater than the mainstream air velocity of the experimental air duct used in the theoretical calculation. Due to the difficulty in measuring the air velocity in the gaps between porous plates, CFD simulations were conducted. The relative errors between the theoretical corrected values calculated with the simulated air velocities and the experimental values were within 10 % for most of the conditions, and between 10 % and 15 % for very few conditions.

Cilia flow of magnetized Eyring-Powell nanofluid in a vertical thermal channel with viscous dissipation: An application of Adomian decomposition method

In this study, authors explore how magnetic fields and the buoyancy force resulting from temperature differences work together. The study is focusing at how an Eyring-Powell nanofluid behaves in a ciliated channel when both natural convection and magnetic effects are at play. A technique called the symplectic metachoronal wave has been used to analyze this analysis. A physical assumption of small Reynolds number is considered to simplify the equations describing the flow rate of the Eyring-Powell nanofluid, making it easier to understand. To get a closed form solution, we have incorporated Adomian decomposition method (ADM). It has been observed that the flow is sped up by 10% with increase in the Eyring-Powell fluid parameter M. The quantity of heat transfer increases with increasing values of the Hartmann, Eyring-Powell fluid parameters, and Brinkmann numbers. This study has implications for bio-inspired engineering, medical applications, and the design of microfluidic devices.

Numerical study of turbulent flows around a cubic obstacle blown from a variable geometry jets diffuser

This research focuses on utilizing numerical simulation to analyse how modifications in the air jet diffuser shape impact the cooling efficiency of electronic parts. The main aim of this study is to understand the physical and thermal mechanisms involved in the process. The study consists in numerically predicting the physical and thermal field of a cubic-shaped obstacle placed in the centre of a square subjected to a resulting flow field created by a transverse flow and a perpendicularly oriented impacting jet. The computations were done at a Reynolds number of 3 410, analyzing three perpendicular impinging jets with the ratio of impinging and cross flow Reynolds numbers α = Rej /ReH having the values of 0.5, 1, and 1.5. The k–ω SST turbulence model was used in this investigation. The effectiveness of the methodology that was put into action was evaluated by referring to the findings derived from the experiments conducted by Masip and his team. Once the methodology was validated, we studied the effect of changing the geometric shapes of the impinging jet diffusers on the cooling efficiency. Three geometrical shapes of air diffusers were tested (circular, swirling and lobed). We noted that there is a direct correlation between flow morphology and cooling efficiency. The impact of the ratio α was analysed and found to have a significant effect on the cooling efficiency. As this ratio increases, the quantity of heat transfer increases in all three air jet diffuser cases. In relation to the lobed air jet, it was observed that the Nusselt number exhibits greater values when compared to the other air jet diffuser cases. Moreover, it was noted that the lobed air jet diffuser can enhance the heat transfer efficiency for α = 1.5 by more than 16.3 % compared to the circular air jet diffuser.

Two-phase thermosyphon loop with different working fluids used in data centers

The two-phase thermosyphon loop (TPTL) is an effective cooling technology used in data centers. TPTLs filled with different working fluids typically have various operating characteristics that influence their practical applications. A comparative experiment was conducted on CO2, R134a, and R410A TPTLs, and differences in their operating states and thermal performances were analyzed. The optimal filling ratio of the CO2 TPTL was 45%, while that of the R134a and R410A TPTLs was 35%. At their optimal filling ratios, all the three TPTLs successively underwent the pre-start, oscillatory, and stable operation stages as the heat transfer quantity increased. The oscillations of the CO2 TPTL were periodic, whereas those of the R134a and R410A TPTLs were irregular. The normal working load ranges of the CO2, R134a, and R410A TPTLs were 550–1200, 760–1160, and 790–1300 W, respectively. When the heat transfer quantity was 1000 W, the driving temperature difference of CO2 TPTL was 2.4 °C lower than that of R410A TPTL and 6.0 °C lower than that of R134a TPTL.

Magnetohydrodynamic and Thermal Performance of Electrically Conducting Fluid along the Symmetrical and Vertical Magnetic Plate with Thermal Slip and Velocity Slip Effects

Numerical and physical simulations of the magnetohydrodynamic mixed convective flow of electrically conducting fluid along avertical magnetized and symmetrically heated plate with slip velocity and thermal slip effects have been performed. The novelty of the present work is to evaluate heat transfer and magnetic flux along the symmetrically magnetized plate with thermal and velocity slip effects. For a smooth algorithm and integration, the linked partial differential equations of the existing fluid flow system are converted into coupled nonlinear ordinary differential equations with specified streaming features and similarity components. By employing the Keller Box strategy, the modified ordinary differential equations (ODEs) are again translated in a suitable format for numerical results. The MATLAB software is used to compute the numerical results, which are then displayed in graphical and tabular form. The influence of several governing parameters on velocity, temperature distribution and magnetic fields in addition to the friction quantity, magnetic flux and heat transfer quantity has been explored. Computational evaluation is performed along the symmetrically heated plate to evaluate the velocity, magnetic field, and temperature together with their gradients. The selection of the magnetic force element, the buoyancy factor 0&lt;ξ&lt;∞ , and the Prandtl parameter range 0.1≤Pr≤7.0 were used to set the impacts of magnetic energy and diffusion, respectively. In the domains of magnetic resonance imaging (MRI), artificial heart wolves, interior heart cavities, and nanoburning systems, the present thermodynamic and magnetohydrodynamic issuesare significant.

Thermographic Investigation on Fluid Oscillations and Transverse Interactions in a Fully Metallic Flat-Plate Pulsating Heat Pipe

The present investigation deals with the quantification of fluid oscillation frequencies in a metallic pulsating heat pipe tested at varying heat loads and orientations. The aim is to design a robust technique for the study of the inner fluid dynamics without adopting typical experimental solutions, such as direct fluid visualizations through transparent inserts. The studied device is made of copper, and it is partially filled with a water–ethanol mixture (20 wt.% of ethanol). Heat fluxes locally exchanged between the working fluid and the device walls are first assessed through the inverse heat conduction problem resolution approach by processing outer wall temperature distributions acquired by thermography. The estimated local heat transfer quantities are therefore processed to quantify the fluid oscillatory behavior in every device branch during the intermittent flow and full activation regimes, thus providing a deeper insight into the heat transfer modes. After dealing with a further validation of the inverse approach in terms of oscillation frequency restoration capability, the wall-to-fluid heat fluxes referred to each channel are processed by means of the wavelet method. Scalograms and power spectra of the considered signals are presented for a time-based analysis of the working fluid oscillations, as well as for the identification of dominant oscillation frequencies. Fluid motion is then quantified in terms of the continuity of fluid oscillations and activity of channels by applying a scalogram denoising technique named K-means clustering method. Moreover, a statistical reduction of the channel-wise dominant oscillation frequencies is performed to provide useful references for the interpretation of the overall oscillatory behavior. The link between oscillations and transverse interactions is finally investigated. The vertical bottom-heated mode exhibits stronger fluid oscillations with respect to the horizontal mode, with fluid oscillation frequencies ranging from 0.78 up to 1 Hz. Nonetheless, the fluid motion is more stable in terms of oscillation frequency between channels when the device operates in the horizontal orientation probably due to negligible buoyancy effects. Moreover, thermal interactions between adjacent channels are found to be stronger when the oscillatory behavior presents similar features from channel to channel in horizontal orientation. The proposed method for fluid oscillation analyses in fully metallic flat-plate pulsating heat pipes can be effectively adopted to other flat-plate layouts without any need for transparent windows, thus reducing the overall complexity of experimental set-ups and providing, at the same time, a good insight into the inner fluid dynamics.

Experimental Study on Combustion and Heat Transfer Characteristics of Li/SF6 based on Unmanned Underwater Vehicle Combustor

Abstract The Li/SF6 combustion reaction can provide power for unmanned underwater vehicle (UUV) due to the advantages of high heat release and no gaseous combustion products. Exploring the combustion and heat transfer characteristics of Li/SF6 can greatly improve the performance of the UUV combustor. In this paper, based on the operation requirements of UUV combustor, the C300 combustion reactor is designed, the Li/SF6 combustion experimental system is established, and the Li/SF6 combustion and heat transfer experiments are performed. The experimental results show that the overall combustion process lasts about 1.55 h, and the flame temperature is higher than 1768 °C. The temperature in the gas phase decreased gradually along the radial direction and increased along the axis. Eight quasi-equilibrium states are detected, and the maximum combustion power is 12.73 kW. As the pressure increases, the combustion power will increase accordingly. Under the maximum power, the heat transfer efficiency of the C300 combustion reactor can be calculated to be η=85.93% by using water as the heat transfer medium. The heat transfer quantity of the combustion furnace Qf is 2.07 times that of the combustion chamber Qc, and the heat generated by combustion is concentrated in the lower part of the combustion reactor. In addition, a thermal resistance model is proposed to optimize the heat transfer process. Finally, the upper fuel is fully combusted, while the bottom fuel is poorly combusted due to the phenomenon of insufficient melting and combustion product covering.

Zero emission /energy building heating through parabolic dish collector focused KNO3–NaNO3 and KNO3–NaNO3–NaNO2 PCM absorber: A case study

Globally During the winter of the year, having a warm place to stay is a necessity, especially true in mountainous regions. Electric heating and biomass burning are the most common methods for this purpose. However, solar PV-based electric heating is a sustainable way to eliminate the cost of heating, which requires more panels and a large floor area. Alternatively, a solar thermal system is used for building heating during the winter season. But the effectiveness and duration of heating support depend on the system's features and the researchers' efforts to maximize them. This research aims to develop a zero-emission/energy-building heating system with a PCM. The influence of PCM choice is validated experimentally to maximize winter heating. Solar parabolic dish collectors (14 sq. m) with two distinct PCM embedded absorbers, such as KNO3–NaNO3 and KNO3–NaNO3–NaNO2, were considered for the investigation to optimize the PCM for the best performance with respect to building heating. The experimental results reveal that the KNO3–NaNO3 PCM outperformed by exhibiting a higher heat transfer rate than the PCM of KNO3–NaNO3–NaNO2. Hence the maximum output water temperature was recorded as 94 °C, and the quantity of heat transfer was 6273 W. The system's energy efficiency was 50.6%, and the exergy was 5.99% with the absorber, which embedded KNO3–NaNO3 PCM. It was found that the black coating decreased heat loss from the absorber's surface, and net heat transfer to the absorber was improved significantly.

Heat transfer analysis of supercritical CO2 in a High-Speed turbine rotor shaft cooling passage

This study investigated the turbulent flow heat transfer in a high-speed turbine rotor shaft cooling passage using CFD. Supercritical CO2 is used as the coolant. The coolant temperature, heat transfer coefficient, convection heat transfer, and frictional heat transfer are investigated. The effect of clearance, mass flow rate, shaft rotational speed, and shaft temperature is also investigated. The result showed that the coolant temperature and heat transfer coefficient are independent of the radial clearance. The significant effect of mass flow rate on the coolant temperature is predicted. The convection heat transfer is substantially higher than the frictional heat transfer. This implies that the convection heat transfer is highly dominant over the frictional heat transfer by which the significant cooling provision could be achieved by the supercritical CO2 fluid through the annulus passage. A little agreement is found when the quantity of heat transfer is predicted using correlation and compared with the result obtained by CFD.

Experimental study on heating performance of micro-holes radiant plate under different installation types in severe cold regions

In order to alleviate energy shortage and maintain comfortable indoor environment, radiant air conditioning system is widely used. This paper designs and produces a miniaturized micro-holes radiant plate, which has the characteristics of orifice plate air supply and radiant heat transfer. The micro-holes radiant plate can be installation on the ceiling or sidewall without adding dynamics system and piping system. In order to explore the heating performance of the micro-holes radiant plate under different installation types, an experimental bench of air source heat pump micro-holes radiant plate heating system was built in Harbin, China, for laboratory heating. The experimental results showed that the indoor average temperature under various installation types could basically meet the set requirements, and the deviation was within 1 °C. The indoor horizontal temperature distribution was relatively uniform, and the temperature difference of each measuring point was less than 2 °C. The indoor vertical temperature difference was the smallest under the installation type with sidewall 50 mm from the ground at only 2.68 °C in the sitting position and 3.14 °C in the standing position, which meet China and ASHRAE standards. The ratio of the radiant heat transfer quantity under the sidewall heating was about 60 %, while the ratio under the ceiling heating was only about 30 %. The maximum ratio of the radiant heat transfer quantity was close to 70 % under the installation type with sidewall 50 mm from the ground. The experimental results provide theoretical support for the design and operation of air conditioning systems in severe cold regions.

A Numerical Study on Swirling Hot Air Anti-Icing with Various Surface Structures on the Internal Wall

Swirling hot air is a promising heat transfer enhancement technology for anti-icing applications in aircrafts, where the swirling flow is accompanied by pretty high turbulence and a quite thin boundary layer. It is of interest to investigate the compound heat transfer characteristics of the swirling air configuration combined with surface structures on the internal wall. This paper carries out a series of numerical computations to obtain the Nusselt number and pressure loss data in such a swirling air heat transfer system with four kinds of surface structures (trenches, ribs, dimples and bulges) on the wall and with different tangential inlet jets placed along the tube. At a tube Reynolds number from 10,000 to 50,000, the results show that the surface dimples and bulges are conducive to improving the Nusselt number, but the surface trenches and ribs show a Nusselt number deterioration relative to the smooth swirl tube. Among the four investigated surface structures, the surface bulges perform best, which can enhance the Nusselt number by up to 15.0%, increase the total heat transfer quantity by up to 17.3% and reduce the hot air pressure loss by up to 15.6%. Furthermore, the circumferential velocity distribution and swirl number are introduced to describe the flow fields. The surface trenches and ribs lead to less of a reduction in the circumferential velocity and swirl intensity, while the surface dimples and bulges could significantly suppress the in-tube swirl intensity.

Study on flow and heat transfer characteristics of cooling channel filled with x-shaped truss array

In order to enhance the cooling performance of turbine blades, novel cooling channels filled with X-shaped truss array were investigated in this study. The flow mechanism and heat transfer characteristic of the cooling channel filled with X-shaped truss array were analyzed numerically. The empirical correlations of friction coefficient and Nusselt number related to the inlet Reynolds number (10000-60000) and truss rod inclination angle (30-45?) were fitted. The results show that the secondary flow vortex in the channel and the Nusselt number on the channel wall both show periodic distributions along the streamwise direction. The row-averaged Nusselt number and friction coefficient of the channel first decrease quickly and then decrease slowly along the streamwise direction. When truss rod inclination angle increases from 30-60?, the whole-averaged Nusselt number and the whole friction coefficient of the channel increase by 25.4-52.3% and 1.19-1.33 times, respectively under different Reynolds number. The channel with truss rod inclination angle of 45? has the best comprehensive thermal performance. In all cases, the ratio of heat transfer quantity of the truss rod surface to the total heat transfer quantity of the channel ranges from 22.9-42.3%. The increase of Reynolds number improves the heat transfer quantity of the channel wall and the increase of truss rod inclination angle reduces the heat transfer quantity of the channel wall.

Experimental study on immersion phase change cooling of lithium-ion batteries based on R1233ZD(E)/ethanol mixed refrigerant

To improve heat dissipation and temperature uniformity for the lithium-ion battery module of electric vehicle, the immersion phase change cooling characteristics of R1233ZD(E)/Ethanol mixed refrigerant were studied experimentally in a staggered battery module, which is composed of 50 batteries. At 101.3 kPa saturated vapor pressure, coupled wall boiling and forced convection heat transfer was analyzed under different discharge rates (1 C, 2 C, and 3 C), filling volume fractions of R1233ZD(E) (0.463, 0.540, 0.630, 0.735, and 0.857), and inlet volume flow rates (652.0, 1086.0, 1521.0, and 2172.0 mL min- 1). Meanwhile, the outlet vapor quality of the two-phase flow was calculated according to energy conservation. The results show that the heat generation of the battery was dominated by the operating current. With the decrease of the output power of the battery, the heat generation first increases rapidly, then increases gently, and finally decreases sharply. When low boiling point R1233ZD(E) was mixed into ethanol, wall boiling heat transfer was effectively enhanced, and the temperature uniformity of the battery module could be improved by up to 57.0\\%. However, the outlet vapor quality of the two-phase flow showed that when the volume fraction of R1233ZD(E) exceeded 0.803, wall boiling departed from the nucleate boiling regime as well as heat transfer and temperature quantities changed accordingly. Forced convection heat transfer of liquid-phase played a leading role in reducing the temperature rise of the battery module, and its contribution increased with the increase of refrigerant inlet flow rate. When the inlet flow rate increased from 652.0 mL min- 1 to 1086.0 mL min- 1, the module temperature rise decreased by 14.8%. Nevertheless, forced convection of liquid-phase weakened battery wall boiling, which adversely affected the temperature uniformity of the battery module.

Multi-Objective Optimization of Plate-Fin Heat Exchangers via Non-Dominated Sequencing Genetic Algorithm (NSGA-II)

The rules of heat transfer and fluid flow in plate-fin heat exchanger are intricate and complex, and the selection of boundary conditions is the key to giving full play to the performance of heat exchanger. In this paper, a multi-objective optimization based on computational fluid dynamics (CFD) and non-dominated sequencing genetic algorithm (NSGA-II) was carried out to obtain the optimal performance of a plate-fin heat exchanger for an extended-range hybrid vehicle engine. The angle of serrated staggered fin, oil flow rate, and water flow rate were taken as input parameters, and the heat transfer quantity, oil pressure drop, and oil outlet temperature were taken as objective functions to perform the optimization analysis of the heat exchanger. Support vector machine regression (SVR) was used to establish the objective function, and the NSGA-II algorithm was adopted to obtain the Pareto optimal solution set. The optimal solution was determined in the Pareto optimal solution set by comprehensive evaluation based on technique for order preference by similarity to an ideal solution (TOPSIS). The results showed that the best comprehensive performance of the heat exchanger was achieved at a fin angle of 63.01°, an oil flow rate of 9.7 L/min, and a water flow rate of 6.45 L/min. At this time, the heat transfer quantity was 9.79 kW, the oil pressure drop was 13.63 kPa, and the oil outlet temperature was 65.11 °C.

CFD Simulation of Tapered Coil by Using Silicon Dioxide and Zinc Oxide Nanofluid with Water and Ethylene Glycol as Its Base Fluid

Abstract: Helical coils are very essential for various heat exchangers, nuclear reactors and in chemical engineering because of large quantity of heat transfer in a small space with high heat transfer rates and slight residence time dispersals even it suffers through a disadvantage of larger pressure drop. The curvature creates secondary flow arrangement which is perpendicular to main axial stream path. The secondary flow has insignificant capability to improve heat transfer owed to mingling of the fluid. The objective of this work is to compare and increase the pressure drop inside tapered helical coil heat exchanger in copper tube to succeed a better and more quantitative insight into heat transfer process by increasing secondary flow inside the coil and this can allow proper intermixing of the fluid and to maintain desired flow rate inside the helical coil. I work on CFD to analyze the helical coil by using ANSYS 15. Generation of 3D CAD model of aluminium and copper tapered helical tube of diameter (d) 10 mm keeping PCD 50 mm, pitch 20 mm , tapered angle 20 and length of 500 mm by using SOLIDWORKS and exporting to the IGES format and then import in ANSYS fluent 15