Fin Heat Research Articles

Visualization research on influencing factors of flat heat pipes

Flat heat pipes can effectively spread a concentrated high power heat source in a small region into a larger heat dissipation area, which is widely used in the thermal management of electronic devices. In this paper, two different sintered copper powder wick structures are designed to study the effect of porous column height on the heat transfer performance. The results show that the best performance is achieved at the 30% filling ratio under the 15 ℃ cooling water with all the porous columns contacting with the condenser. The heat power is 312.7 W and the thermal resistance is 0.192 ℃/W. As the cooling water temperature increases, the evaporation rate increases, resulting in a decrease in the thermal resistance. But the decrease in temperature difference causes the decline in heat dissipation power. Through the visual observation, it is found that the porous column contacting with the condenser can not only play the role of support and liquid reflow pathway, but also serve as an effective evaporation area to improve the heat transfer performance. While the low porous column cannot transport the condensed liquid and is completely immersed by the liquid under the high filling ratio, which is difficult to promote evaporation rate. In order to improve the performance at air cooling situation, an integrated heat pipe combined the flat heat pipe and fin tubes is designed, which can achieve a heat power of 259.8 W and present excellent temperature uniformity. This research provides the guidelines to optimize the heat transfer performance of porous column wick structures.

Performance Study of the Thermoelectric Personal Cooler under Different Ambient Temperatures

In this study, a Thermo Electric Cooler (TEC) was manufactured and investigated experimentally. The heat sink, geometry, fin number, fin length, and heat sink dimensions are studied theoretically. The performance of the TEC is studied under three variables, namely: the THC power, airspeed, and ambient temperature. Two heat sinks are used for each Peltier module. The first one is for the cooling side, while the second one is for the hot side. In the theoretical part, the geometry and the dimensions of the heat sink are studied using one-dimensional heat transfer equations, as well as a theoretical simulation of the performance of a single Peltier module is achieved. The results show that the cooling capacity increases with the increase in airspeed, and the maximum cooling capacity was 180 W at an airspeed of 4 m/s and TEC power of 300 W. The maximum figure of merit of the TEC is about 0.23 when the TEC power is 350 W, at 4 m/s airspeed and an ambient temperature of 43℃. The theoretical results showed that the number of fins affected the total sink thermal resistance and that thermal resistance reduced sharply from 6.5 to about 2 m2 K/W when the fin number increased to 6. When the TEC power is 350 W, the airspeed is 4 m/s, and the ambient temperature is 28℃, the maximum TEC efficiency is 0.5%. Finally, the comparison between the current work and the other works shows the same trends in the variables under comparison.

A Convenient Method for the Accurate Calculation of Fin Efficiency of H-Type Fins Based on Linear Nomograms and Fitting Formulae

Fin efficiency, as a measure of the effectiveness of the heat transfer enhancement, is of great importance in studying the heat transfer performance of H-type finned tube banks. The fin efficiency of square fins is adopted by most researchers as an alternative to that of H-type fins, which can create certain errors in the fin efficiency of H-type fins. For this paper, the linear nomograms and fitting formulae of fin efficiency of H-type fins are obtained by the definition method of fin efficiency based on numerous numerical simulations, and the results calculated by this method are verified by experimental data. On this basis, the effects of three geometric parameters (slit width, fin height, and fin thickness) and two thermal parameters (surface heat transfer coefficient and fin thermal conductivity) on the fin efficiency of H-type fins are also investigated and compared to those of square fins. The results indicate that the fin efficiency of H-type fins increases with the increment of fin thickness and thermal conductivity, and decreases with the increase of slit width, fin height, and surface heat transfer coefficient. Accordingly, the linear nomograms and fitting formulae for the fin efficiency of H-type fins, which are well compatible with experimental data, can help to facilitate further theoretical research and engineering application.

Simulation of fin and tube heat exchanger and validation with CFD analysis

Heat exchangers plays significant role in engineering because they transfer heat between two different flow streams and temperatures. There are various designs of heat exchangers based on construction, size, direction of fluid flows. Amongst, industries including oil & gas, power generation, marine, and HVAC&R has the most prevalent application for fin and tube heat exchangers in the broad range. Proper analysis is required prior to the selection of suitable application-specific heat exchanger with good heat transfer characteristics. In the present work, Fin and Tube heat exchanger has been considered for the analysis using ANSYS2021 Fluent. The same model has been simulated and compared with MATLAB Simulink. Variation of heat transfer parameters such as fin side heat transfer coefficients and fin efficiency with mass flow rates and geometric parameters have been observed. Results obtained from the CFD analysis have been validated with mathematical simulation and the reasons for variations in result have been identified and discussed. Some of inferences obtained with both the works has been discussed.

Heuristic technique for multi-objective optimisation of engine cylinder fins

In this paper, we perform an analysis of an engine fin array, of the conventional circular type, for both heat dissipation and fin material cost. The set of designs proposed are non-dominated in nature and serves both objectives reasonably. The Non-dominated Sorting Genetic Algorithm (NSGA-II) is used to optimise the factors affecting the heat transfer and the material cost. The bore radius, fin thickness, fin length, number of fins, and velocity of air around the fins are taken as parameters for the multi-objective optimisation. The Steady State Thermal module of ANSYS 19.0 software is used to compute the fitness function, which is an integral part of GA. This work aims at developing an integrated solution technique by combining the ANSYS software with Genetic Algorithm (GA) which will increase the accuracy and speed in obtaining the results. The results attained show that the proposed method offers an efficient and robust optimisation technique.

Numerical Study on Heat Transfer Characteristic of the Plate-Fin Microchannel Heat Sink for Water-Based Thermal Management of CPU Chip

For effective water-based thermal management of high heat generating CPU chip, a series of numerical simulation has been conducted to study the effects of heat flux, fin height and flow rate on convective thermal performance of the plate-fin microchannel heat sinks. The characteristics of heat transfer and flow resistance have been quantificationally discussed and <i>JF</i> factor is employed to evaluate the comprehensive efficiency of convective heat transfer of microchannel heat sink. Results show that the increase in fin height and flow rate of cooling water is helpful to decrease the maximum temperature of CPU chip. Large flow rate and heat flux and short fin height are benefit to improve Nusselt number <i>Nu</i>, but they lead to large resistance coefficient <i>fRe</i> simultaneously. Analysis of <i>JF</i> factor shows that the microchannel with short fins shows better convective thermal performance when the thermal power of the CPU chip is small. The fins should be heightened when the CPU is operating at higher thermal power. The employment of <i>JF</i> factor in the present work shows its pertinence and convenience in the application of design of microchannel heat sink.

Improving thermal performance of battery at high current rate by using embedded heat pipe system

This study establishes a resistance-based thermal model for the battery cooled by the heat pipe. Unlike the traditional thermal model, the proposed battery thermal model includes the influence of the battery temperature, state of charge (SOC) and current on the heat generation in the battery body. Moreover, it also integrates the heat generation inside the tabs to improve its prediction accuracy. The heat pipe model is developed based on the thermal resistance of its components, and this model is integrated with the battery thermal model to form the thermal model of the BTMS based on the embedded heat pipe system. Experiment are carried out to verify the prediction precision. At the level of the battery unit, the prediction error is within 1 °C. Then, the different heat pipe number, fin number and heat transfer coefficient at the condensation section of the heat pipe are used for the embedded heat pipe system in order to improve its cooling performance. According to the research results, increasing the heat pipe number can reduce the battery temperature and its difference. However, when the heat pipe number is over a certain threshold, both the battery temperature and temperature difference change little. Although the heat transfer coefficient has limited influence on the battery thermal behavior, increasing the heat transfer coefficient and fin number at the same time can reduces the battery temperature a lot. In addition, comparative studies show that the embedded heat pipe system significantly outperforms the bar-type heat pipe and flat heat pipe at an extreme high current rate.

Performance of thermoelectric conversion device with power management module based on shallow soil-air temperature difference

The development of wireless sensor technology has provided an alternative research direction for monitoring of the Internet of Things. However, the practical application of wireless sensor technology is currently constrained by power supply requirements and the rather laborious task of replacing or maintaining the sensor batteries. In this paper, a wireless node power supply system based on the temperature difference between the shallow soil-air was designed. The distinguishing features of this device include application of a gravity heat pipe, thermoelectric generators (TEGs), copper heat fins, and radiators to absorb, transfer and convert the thermal energy. The study measured the performance of the proposed device in an experimental outdoor platform, the results show that in the 8 h monitoring of a day, the temperature difference of thermoelectric device ranged from 12.96k to 24.69k, the peak voltage of the device was 722.13 mV and the peak power was 3.62 mW when the proposed device was at the optimal external load. Furthermore a power management system was designed to increase the output voltage and eventually store it in the supercapacitor. In conclusion, The system provides an effective mechanism for solving the energy supply problem of wireless sensor.

An Investigation of Heat Transfer and Pressure Drop Enhancement of Various Perforated Circular Finned Tubes at Different Tube Tilt Angles

The thermal and flow performance of the circular annular finned tube heat exchanger with perforated fins were investigated numerically using ANSYS Fluent 2020 software, RNG k-e model with enhanced wall treatment, global performance criterion was introduced as evaluation factor of the heat exchanger performance, the parameters to be investigated were the number of holes, size of hole, tilt angle of the finned tube, fin height and spacing between fins. Agreement was found with literature that the tilt angle causes increase in heat transfer rate and increase in the pressure drop as well, but the change the global performance criterion as function to tilt angle depends on the fin heights, for higher fin heights the effective change of the pressure drop become greater than the increase in the heat transfer rate and the contrast occur in the cases of smaller fin heights, we have found that the perforation in tilted annular circular finned tubes causes an increase in the heat transfer rate and an enhancement in the total heat exchanger performance, increasing the number of holes will enhance the performance of the heat exchanger and the spacing increase reduces the heat exchanger performance.

Effect of Attack Angle of Concave and Convex Winglets Vortex Generators on Thermal-Hydraulic Performance of Fin and Tube Heat Exchangers with Field Synergy Principle

In fin and tube heat exchangers, the gas passing through the fin has a lower thermal conductivity than the fluid passing through the tube. The low thermal conductivity brings a high thermal resistance, which suppresses the heat transfer rate. A common practice to enhance fin-side heat transfer is to generate longitudinal vortex by mounting vortex generators (VGs) on the fin. This paper aims to investigate how longitudinal vortex generator (LVG) improves heat transfer and pressure drop. Numerical simulations were carried out to analyze three types of VGs. The installation of VGs was varied with the attack angle changing from 10°, 15°, to 20° with a 1-3-4-7 VG arrangement on the tube. The flow velocity was expressed in Reynolds number (Re) between 364 and 689. The enhancement of heat transfer rate and improvement of pressure drop were analyzed between three types of VG, three different attack angles, and four types of winglet installation, compared to baseline. The simulation results show that the highest convective heat transfer coefficient (84.85%) was achieved by the VG composed of seven concave delta winglet pairs (CDWPs) at the attack angle of 20° and Re = 689; CDWP VG provides the highest heat transfer improvement among all cases.

Effect of heat transfer area distribution on frosting performance of refrigerator evaporator

The present study investigates the effect of the distribution of available heat transfer area on the thermohydraulic behavior of a typical fin-and-tube type evaporator used in a domestic frost-free refrigerator. Previous studies in the literature have not explored the effect of the number of fin rows and fin pitch distribution across the fin rows on the performance of fan-supplied evaporator geometries under frosting. The present study attempts to address this by developing a thermohydraulic model of the evaporator to predict the heat transfer rate, pressure drop and frost formation. A distributed evaporator model is developed by dividing the evaporator into individual control volumes and the balance equations are applied along with a suitable semi-empirical frost growth model to predict the rate of frost formation. Experiments were performed in a purpose-built test facility to validate the numerical model. The developed model is employed to compare different heat exchanger geometries with a constant area but varying in total fin rows and fin pitch distribution. Results show that distributing the available heat transfer area among a higher number of fin rows results in longer successive defrost intervals. However, the evaporator occupies more volume. For a given heat transfer area and fin rows, longer operating time can be achieved by selecting fin pitches that provide uniform blockage ratio across the fin rows. It is observed that for a specific fin pitch at the leading row, reducing the fin pitch linearly across the fin rows resulted in uniform blockage ratio across the fin rows.

Exact, analytical heat transfer from longitudinal radiating fins of rectangular profile in a tube/fin ensemble

AbstractIn this technical note, the problem concerning the quantification of heat transfer rates from an array of longitudinal radiating fins of rectangular profile in a tube/fin ensemble to a nonzero temperature sink is investigated. Radiating fins constitute essential elements in the thermal control of spacecrafts and satellites. We consider quasi one‐dimensional heat conduction in the longitudinal radiating fins and neglect radiative exchange between the fins and the tubes carrying a hot fluid. It is demonstrated that the governing nonlinear differential equation of second order with constant coefficients and nonhomogeneous can be solved in exact, analytical implicit form. The pertinent temperature distributions eventually provide the magnitudes of heat transfer rates and fin efficiencies influenced by the radiation–conduction parameter and the sink temperature.

Application of the Trefftz Method for Pool Boiling Heat Transfer on Open Microchannel Surfaces

In the paper, the results of tests on pool boiling heat transfer on open microchannel surfaces were discussed. Nucleate pool boiling from copper microchannel surfaces was examined using ethanol as a working fluid. Parallel microchannels fabricated by machining were about 0.2 to 0.4 mm wide and 0.2 to 0.5 mm deep. In the mathematical model the heat transfer process was in steady state. The heat transfer in copper block was assumed axisymmetric while the specimen temperature distribution was not. The temperature of the copper block and the specimen were assumed to satisfy Laplace’s equations with adequate boundary conditions. The problem was solved by the Trefftz method with two sets of Trefftz functions. Graphs were used to represent the copper block and the specimen temperature distributions, local values of heat transfer coefficients as a function of the heat flux and fin temperature distribution. Uncertainty analysis was presented.

Experimental Enhancement of Mixed Convection Heat transfer in Hot Base Rectangular Channel

This paper presents an experimental study to enhance the flow and heat transfer enhancement over horizontal and orientation channel with hot base by laminar mixed convection heat transfer. The hot base is fitted with the longitudinal rectangular fin arrays as a finned wall. The study covered the following range: modified Grashof number varied (3× 101 - 8× 108), Reynolds number in range 1800-2300, and Pyrantel number 0.71. The bottom finned wall of the channel was supplied with constant heat flux, while the other sides are insulated. The experiment part includes a suitable test rig that was built to get accurate decisions. A good mechanism was created to get the orientation angles at (90°,120°, 150 °and 180°) then to analysis this effect on heat transfer for laminar flow force convection. Three different cases are investigated: the effect of modified Grashof number and orientation angles on fluid particles flow and heat removal will be an enhancement. The experiment results show that the average heat transfer coefficient increased with Reynolds number and an increase of the Grashof number for all orientation angles due to increases buoyancy forces, thus causes a detach with the secondary layer flow. The average heat transfer coefficient and fins effectiveness are enhanced to 25% at highest longitudinal orientation angles.

Review on Heat Transfer Enhancement by Louvered Fin

The heat transfer enhancement is recycled in many engineering uses such as heat exchangers, refrigeration and air conditioning structures, chemical apparatuses, and automobile radiators. Hence many enhancing extended fin patterns are developed and used. In multi louvered fin, in this segment for multi-row fin and tube heat exchanger, an increase in heat transfer enhancement is found 58% for ReH = 350. When the Reynolds number is 1075, the temperature gradient is more distinct for greater louver angle that is the higher heat transfer enhanced for large louver angle. For variable louver angle heat exchanger, the maximum heat transfer improvement achieved by 118% Reynolds number at 1075. In the vortex generator for the delta winglet vortex generator, the extreme enhancement of heat transfer increased to 16% compared to the baseline geometry (at ReDh = 600). For a compact louvered heat exchanger, the results showed that a regular arrangement of louvered fins gives a 9.3% heat transfer improvement. In multi-region louver fins and flat tubes heat exchanger, the louver fin with 4 regions and the louver fin with 6 regions are far better than the conventional fin in overall performance. At the same time, the louver fin with 6 regions is also better than the louver fin with 4-region. The available work is in experimental form as well as numerical form performed by computational fluid dynamics.

Studi Eksperimental Pergerakan Temperatur Radiator Terhadap Putaran Mesin (RPM) dengan Kecepatan Kipas Constant

The research aims to evaluate the engine rotation (rpm) against changes in radiator temperature. Radiator used is compact heat exchanger tube and fins type. The study was conducted using an experimental method on a BMW E.36 car with a stop state. The research scheme we use consists of radiator water reservoir tanks, water pumps, and radiators. Measuring instruments used are anemometer, thermocople, stopwatch and reader. Data retrieval is carried out at the radiator entrance temperature, radiator exit temperature and the temperature on the radiator wall that hits the fan. In this study we did variations of engine rotation (rpm) of 1000, 1500, 2000, 2500 and 3000 rpm. The results showed that in the use of fans at a speed of 6.5 m / s able to throw heat into the environment well, this proved to be obtained the highest temperature value at the 10th minute of 57.5 oC at a fan speed of 3.5 m / s. Meanwhile, in the 10th minute the lowest temperature was obtained from a speed of 6.5 m/s of 40 oC.

EXPERIMENTAL AND NUMERICAL STUDY OF INSERTING AN INTERNAL HOLLOW CORE TO FINNED HELICAL COIL TUBE-SHELL HEAT EXCHANGER

In the present study, an experimental study and a numerical method are used to simulate the effect of utilizing finned helical coil heat exchanger horizontally oriented with and without internal hollow core inside the shell and monitoring the heat transfer intensification behavior and performance enhancement, by using ANSYS FLUENT 2019R3 package. The working fluid in the inlet side of the coil will be superheated vapor refrigerant (R410a) after the compression stage of the air conditioner (1TR) split type, the working fluid in the shell side is water with various flow rates (1,2 and 3) LPM. Found that when using a heat exchanger with internal hollow core reduces the time needed to reach the steady-state outlet temperature and directly proportional to the size of the core by 20% and slightly increasing the water outlet temperature by 5%.

Thermal analysis of novel heat-sink fins for FDM 3D printer liquefier

Fused deposition modelling (FDM) is the most affordable 3D printing process available in the market. Plastic wire filaments are fed inside the extruder and heated by a heating coil to heat the plastic sufficient to have a consistent flow. The filament within the extruder must remain solid at room temperature for it to act as a plunger for the part of the filament being melted near the nozzle. A uniform thermal distribution must be maintained for the sake of the filament’s consistent flow rate. The extruder will face both mechanical and thermal load. Proper heat dissipation is critical because it directly affects the performance of the extruder and thereby impacts the product produced. Since the extruder head should be compact and resilient to thermal loads, the designing of heat fins with minimum material and maximum surface area is important. This paper presents a finite element numerical analysis of the heat transfer in the filament extruder of a 3D printer with multiple novel cooling fin design configurations. The analysis was done using Ansys Workbench and the novel fins showed promising results.

Effect of Surface Modification with Aluminium and Copper on the Performance of Stainless Steel 304 Fin

In this present work, experiments were performed on coated Stainless Steel 304 fin to understand the effect of coating on heat transfer parameters of fin. Aluminium and Copper were chosen as coating materials and these were coated on the Stainless steel 304 substrate by using Thermal Spray Method. Conducted experiments on different coated and none coated fins at various heat inputs using Fin-Pin apparatus in our heat transfer laboratory and necessary readings were noted to calculate Reynolds Number, Nusselt Number, Heat transfer coefficient, Thermal conductivity and fin efficiency. The value of thermal conductivity of fin without was obtained as 52.3 W/m K, coated with Aluminium as 166.75 W/m K and coated with Copper as 280.6 W/m K. The improvement of percentage of fin efficiency in case of fin coated with Aluminium was obtained as 73.6% compared with fin without coating, but in case of fin coated with Copper was obtained as 81.7% compared with fin without coating and 4.6% compared with fin coated with Aluminium.

Enhancing the Thermal Performance of Slender Packed Beds through Internal Heat Fins

Slender packed beds are widely used in the chemical and process industry for heterogeneous catalytic reactions in tube-bundle reactors. Under safety and reaction engineering aspects, good radial heat transfer is of outstanding importance. However, because of local wall effects, the radial heat transport in the vicinity of the reactor wall is hindered. Particle-resolved computational fluid dynamics (CFD) is used to investigate the impact of internal heat fins on the near wall radial heat transport in slender packed beds filled with spherical particles. The simulation results are validated against experimental measurements in terms of particle count and pressure drop. The simulation results show that internal heat fins increase the conductive portion of the radial heat transport close to the reactor wall, leading to an overall increased thermal performance of the system. In a wide flow range (100&lt;Rep&lt;1000), an increase of up to 35% in wall heat transfer coefficient and almost 90% in effective radial thermal conductivity is observed, respectively.