Wavy Fin Research Articles

Investigation of the heat transfer and flow characteristics in wavy fins of compact heat exchanger in a sand-dust environment

The thermal-hydraulic characteristics of aluminum wavy fins of compact heat exchangers in a sand-dust environment are currently unclear. Therefore, in this paper, the effects of particle concentration and size on the heat transfer and pressure loss characteristics of wavy fins, which are analyzed experimentally and numerically, are discussed. In addition, correlation functions of the Colburn and friction factors built using a multiple nonlinear regression based on orthogonal numerical simulation results are presented. It is found that the two-way coupling between the air and the particles can improve the synergy of the velocity and temperature gradient fields. In addition, this coupling can restrain the air turbulent kinetic energy in the near-wall flow zone. Note that the combination of these two effects increases the average Colburn factor. Moreover, as the particle concentration increases in the range of 5-95 g/m3, both Colburn and friction factors increase almost linearly. On the contrary, these factors decrease roughly exponentially as the particle size changes from 10 to 25 μm. It is worth noting that the Colburn and friction factors change with different rates under different Reynolds numbers so that smaller Reynolds numbers result in higher changing rates of both factors. Furthermore, the thermal-hydraulic performance (heat transfer versus pressure difference) of wavy fins decreases slightly in a sand-dust environment when compared with the conventional environment, but it is insignificant on the whole.

Optimisation of the Geometric Parameters of Longitudinally Finned Air Cooler Tubes Operating in Mixed Convection Conditions

The results of optimisation calculations presented in the article are related to longitudinally finned tubes of a heat pump evaporator operating under natural wind-induced flow of outdoor air conditions. The finned surface is characterised by an unusual, wavy fin shape. The article presents the methodology applied to seeking optimal geometric parameters of the finned tube in which thermal calculations were performed by modelling a mixed convection process on the finned surface using the finite volume method. In the case of maximising the heat flow with the minimum mass of the fins, the optimal solution was dominated by the minimum mass of the fins and thus geometric parameters correspond to the number of fins n = 6, fin height h = 0.065 and fin thickness s = 0.0015 m. Optimisation calculations made for maximum efficiency of the exchanger at constant mass indicated that the tube with ten fins (n = 10) with a height of h = 0.11 m and a thickness of s = 0.0018 m allowed maximum heat flow at the assumed mass of the fins in the exchanger tube model. The article proposes a simplified method of determining the optimal geometric parameters of the profile for any mass and maximum thermal efficiency.

Investigation of fin geometries impact on thermal efficiency of solar dryer

Thermal Numerical modeling and aerodynamic processes taking place in a V-corrugated solar air heater and wavy shaped fins is performed. The analysis of this study is done through ANSYS software. The technological variables (the Reynolds number) on heat-exchange processes influence of design (the step between the fins) and flow aerodynamics was also established. Pictorial contours are determined for the velocity distribution, pressure, and other characteristics of the airflow in the solar air-heater box. Thermodynamic characteristics and effective values of technological parameters for the effective use of a solar air heater also studied. V-corrugated and wavy fin used Heat transfer correlations were created with the help of experimental outcomes with respect to the parameter considered for this investigation.

Exergy efficiency design for multi-stream plate-fin heat exchangers based on entropy generation assessment

The fundamental concepts of energy, entropy and exergy are progressively introduced for deepening. Furthermore, the state corresponding to the designated exergy is creatively defined as the referential assessment benchmark so as to asymptotically reckon the optimal rigorous operation decisions. Inspired by bionics design, the different types of lateral perforated fins and wavy fins are designed for various application scenarios. The temperature, T-Q diagram, entropy generation, dimensionless entropy generation, exergy loss and exergy efficiency within either stream or system hierarchy are observed to evaluate the adjustable design portfolio, for trade-off between benefits and costs. The proposed entropy generation assessment (EGA) is verified by physical experiment under different Reynolds number. The results prove that, the net cost of multi-stream plate-fin heat exchangers (MPFHE) is reduced from 20,813 $/kW to 19,072 $/kW after using EGA by −8.36%, while maintaining exergy efficiency. Therefore, EGA herein has important perspicacity for energy availability utilisation and operating economical assessment among heat exchange fields.

Exergy efficiency design for multi-stream plate-fin heat exchangers based on entropy generation assessment

The fundamental concepts of energy, entropy and exergy are progressively introduced for deepening. Furthermore, the state corresponding to the designated exergy is creatively defined as the referential assessment benchmark so as to asymptotically reckon the optimal rigorous operation decisions. Inspired by bionics design, the different types of lateral perforated fins and wavy fins are designed for various application scenarios. The temperature, T-Q diagram, entropy generation, dimensionless entropy generation, exergy loss and exergy efficiency within either stream or system hierarchy are observed to evaluate the adjustable design portfolio, for trade-off between benefits and costs. The proposed entropy generation assessment (EGA) is verified by physical experiment under different Reynolds number. The results prove that, the net cost of multi-stream plate-fin heat exchangers (MPFHE) is reduced from 20,813 $/kW to 19,072 $/kW after using EGA by −8.36%, while maintaining exergy efficiency. Therefore, EGA herein has important perspicacity for energy availability utilisation and operating economical assessment among heat exchange fields.

Natural convection from perforated vertical fins with different hole diameters

Natural convection is a physical mechanism that is mostly benefited in cooling of electronics. Due to the variety of the geometrical and operational parameters, industrial and scientific studies are continuing for better performance. One of the focuses is on perforations of heat sink fins as a passive flow control technique. This work experimentally investigates a sinusoidal wavy fin heat sink after fins were perforated with two different hole diameters. Heat sink was heated by using an electrical resistance for six different heating powers. The temperature at the heater-heat sink interface was measured with the aid of four thermocouples. Transient and steady temperature values were measured and then recorded by means of a data-logger. The details of the experimental setup are given alongside of visuals. It is desired to state some assessment and evaluations about the experimental setup. Related literature studies are also summarized in the introduction section. Heat transfer, Rayleigh and Nusselt numbers were calculated and compared with each other and parameters by means of 2D plot graphics. The time for reaching steady state is changing between 1.5 to 2 hours. Average wall temperature changes linearly with heating power. Average wall temperature values are between 300 and 370 Kelvin. Nusselt number increases with increasing Rayleigh number as expected. While Rayleigh number changes between 500,000 to 5,000,000 Nusselt number approximately increases from 18 to 25. 3 mm perforations yield better results in terms of Nusselt numbers, which means better thermal convection. Surface temperature trends are similar according to power increments. Considering experimental uncertainty, general performances of the two heat sinks are found similar. Some remarks for the future work are given in conclusion section.The original article was published on 31 December 2018 https://dergipark.org.tr/en/pub/ijeat/issue/42280/505116

Numerical thermal performance investigation of phase change material integrated wavy finned single pass solar air heater

The present numerical study comprises thermal performance investigation of double glazed single pass solar air heater exhibiting wavy finned absorber plate integrated with and without PCM. The main objective of the present research work is to design sustained solar air heating systems that can efficiently perform during sunshine, off sunshine and nocturnal hours. In this direction, Design-I (wavy fined solar air heater without PCM) and Design-II (wavy fined solar air heater with PCM) are investigated to obtain the best values of the geometrical and flow parameters. In the present work, first, investigation is carried out to obtain optimum values of geometrical and flow parameters for Design-I, work is then extended to investigate the Design-II exhibiting wavy absorber plate and PCM. MATLAB codes are developed to carry out numerical investigations under transient conditions using an implicit scheme to study the effect of geometrical parameters i.e. amplitude(0.005≤α≤0.015m), wavelength (0.03≤λ≤0.1m) and number of fins (5≤n≤25), and flow parameter i.e. mass flow rate (0.005≤m˙≤0.0128kg/s). The maximum outlet air temperature for Design-I corresponds to optimum values of geometrical parameters obtained at a mass flow rate of 0.005 kg/s, 0.0075 kg/s and 0.01 kg/s is 85.44 ̊C, 73.34 ̊C and 64.9 ̊C, respectively. However, the maximum thermohydraulic efficiency is predicted to be about 47% at the mass flow rate of 0.01 kg/s. Results of Design-II revealed 10 hours thermal backup after sunset at the mass flow rate of 0.0128 kg/s. In addition, investigation for Design-II is extended to present a cold weather condition of an average ambient air temperature of 15oC and an off sunshine hour situation to present possible thermal backup of Design-II. The results of this investigation delineated that using wavy fins on the top and PCM on the bottom side of absorber plate can efficiently provide appreciable instant and high thermal efficiency and thermal energy backup during sunshine, off sunshine and nocturnal hours.

Experimental and numerical studies on heat transfer enhancement for air conditioner condensers using a wavy fin with a rectangular winglet

The air side thermal performance of wavy fins with rectangular winglets are studied using experimental and numerical methods. The following parameters are selected for investigation: the attack angle, placed location, span and length of the rectangular winglet. The results show that all parameters affect the thermal performance of the air side. The best configurations of the winglet that provide the maximum j/f(1/3) for both winglet lengths are the 3.5 mm horizontal distance, 7 mm vertical distance, 60° attack angle and 1.25 mm winglet span. Moreover, the thermal performance comparisons between the optimal design of the wavy fin with winglet and normal wavy fin are reported. Wavy fins with winglets provide a larger heat transfer coefficient, pressure drop and j/f(1/3) than those of normal wavy fins. For the j/f(1/3) comparison, wavy fins with winglets provide a j/f(1/3) greater than that of normal wavy fins by 5.4–14.6 %, with the Reynolds number ranging from 1650 to 4423.

Thermal and hydraulic characteristics of a hybrid nanofluid containing graphene sheets decorated with platinum through a new wavy cylindrical microchannel

One approach to improve cooling efficiency of cylindrical microchannel heat sinks (CMCHS) is increasing the total wetted surface through cylindrical geometries instead of using flat configurations. In addition, the wavy structures using advanced working fluids is a novel technique to enhance the heat transfer in CMCHS. In this study, by using a graphene-platinum/water hybrid nanofluid as the working fluid, the effect of wavy-shaped fins on hydro-thermal performance of a cylindrical CMCHS is investigated numerically. Three-dimensional, steady, laminar flow is simulated using the finite volume method. The sinusoidal fins form the secondary flows in the channel, which disturb the boundary layer leading to intensification in heat transfer. Increasing the amplitude, concentration, and Reynolds number decrease the thermal resistance and facilitate heat transfer. The maximum value of the average heat transfer coefficient is calculated as 13387 W/m2K, while the highest pumping power and lowest thermal resistance are calculated to be 0.6 W and 0.031 K/W, respectively. A comparison between the wavy and straight CMCHSs shows that wavy fins can improve the heat transfer coefficient by up to 75%. The maximum performance evaluation criterion (PEC) is obtained at a concentration of 0.02% and Reynolds number of 600 for all amplitudes. Finally, multi-objective optimization is performed to find the optimal states that yield the highest heat transfer coefficient, lowest thermal resistance, and lowest pumping power regarding the designers’ demands. Optimization is conducted using genetic algorithm and the compromise programming method. The results obtained from the optimization indicate that nanoparticle concentration profoundly affects pumping power, while amplitude has severer influence on the thermal attributes. The main novelties of this work are to employ wavy fins in a CMCHS, as well as to use multi-objective optimization with regard to the relative importance of heat transfer and pumping power in this configuration.

Thermomechanical Analysis of a Bio‐Inspired Lightweight Multifunctional Structure

This work investigates the thermal and mechanical performance of a bio‐inspired lightweight structure, which is inspired by the porous (up to 93% porosity) internal skeleton of cuttlefish, also known as cuttlebone. The potential of using this structure as an air‐cooled heat sink for electronic devices and an integrated thermal protection system (ITPS) is tested and systematically compared with three conventional structures based on wavy, pyramid, and cylindrical pin fin geometries. When cooling a hot spot (100 × 100 × 2 mm3) subjected to heat flow (250 W), and given the same solid volume fraction, the wavy and cuttlebone structures reduce the maximum temperature to 57 °C, which is 13 and 19 °C lower than for the pin fins and pyramid structures, respectively. Concerning the ITPS application, the cuttlebone exhibits the most isometric deformation with a 0.062 mm maximum standard deviation among its four corners. Moreover, the cuttlebone outperforms the other structures in terms of compressive strength (20%, 17%, and 219% increase compared with the wavy, pyramid, and pin fin structures, respectively). More importantly, the simulations indicate that the cuttlebone structure undergoes a graceful failure process due to the sequential buckling of the vertical walls compared with other structures.

Modeling and experimental investigation on comprehensive performance of perforated wavy fins for heat pump type air conditioners at frosting and non-frosting conditions

Perforated wavy fin is a promising type of fin to improve the comprehensive performance of a heat pump type air conditioners (HPAC) which should work with high efficiencies at both frosting and non-frosting conditions. The purpose of this study is to propose a comprehensive performance model of perforated wavy fins for the fin design of HPACs. The comprehensive performance model of perforated wavy fins is established is established for analyzing the total heat transfer performances (UA) at both frosting and non-frosting conditions, and a novel frosting model is developed to predict the effect of perforated wavy geometries on frost performance. The optimal fin geometries are figured out based on the query charts plotted by the comprehensive performance model. A practical perforated wavy fin is designed and manufactured, and an experimental validation on the comprehensive performance model as well as the performance of proposed fin has been conducted. The experimental validation shows that the predicted results of UA and frost morphology are highly in accordance with the experimental data; and the heat transfer capacities of the perforated wavy fin at the frosting and the non-frosting conditions are 4.1% and 8.9% higher than those of the traditional wavy fin, respectively.

Heat transfer augmentation in a pipe with 3D printed wavy insert

The improved vortex generation insert for heat exchanger is measured in this research paper. The wavy insert is adopted to enhance the performance of heat transfer in the tube. The wavy fin is produced by 3D printing and Acrylonitrile Butadiene Styrene (ABS) is used to be the fin's material. The experiment is performed to determine the thermal and fluid flow characteristic. The wavy fin is mounted on the top of tape to produce the flow circulations inside the tube. The Reynolds number from 4004 to 18,173 are selected to be the testing range. The geometric parameter, Amplitude to Height of wavy fin (A/h = 0.5, 1.0 and 1.5), is considered. The experimental investigation signify that the wavy insert with A/h of 1.5 can show higher Nusselt number ratio than A/h of 1.0 and 0.5 about 8% and 16%. The maximum heat transfer enhancement performance for using wavy insert with A/h of 1.5 is observed to be 1.51 at lowest Reynolds number of 4004. Furthermore, the empirically achieved correlations for friction factor and Nusselt number are expressed and compared with experimental data within ±5% deviation.

Detailed Design Optimization of Three-Fluid Parallel-Flow Plate-Fin Heat Exchanger Using Second Law Analysis

Abstract Compact parallel-flow three-fluid heat exchanger (TFHX) of plate-fin type is optimized for attaining the minimum entropy generation unit. Four different types of plate-fins (plain rectangular, offset strip, corrugated louvered, and wavy fin (WF)) which are embodied within heat exchanger have been selected for the study under both cocurrent and countercurrent flow arrangements. The range of the decision variables are 0.3≤ma, mb, mc≤3, 0.1≤Ø≤0.95, 0.1≤Lx, Ly≤2, 0.015≤H≤0.033, 100≤n≤700, 0.0001≤tf≤0.0002, 0.001≤l≤0.009, 0.01≤Lwav≤0.09, and 0.001≤A≤0.005. Genetic algorithm is selected as an optimization tool that is apt in handling various continuous and discrete variables and the problems with the complexities in the objective function as well as in constraints. Validation of the optimization model is carried out by comparing the optimum results with that obtained from the experiments, particle swarm optimization (PSO) (under without heat duty constraint), and graphical method (under with heat duty constraint). It is observed that for a specified heat duty (180 kW) and given operating conditions, corrugated louvered fin (CLF) with countercurrent flow arrangement offers the minimum entropy generation among all. It is riveting to learn that the optimum results occur for most of the considered cases when the flowrate of the central hot fluid is lower than that of the adjacent fluids. At fixed Re = 3000 for all the fin types, off-set strip fin is the most favorable one, and plain rectangular fin (PRF) offers the worst solution comparatively.

Configuration and Optimization of a Minichannel Using Water-Alumina Nanofluid by Non-Dominated Sorting Genetic Algorithm and Response Surface Method.

Nanofluids in minichannels with various configurations are applied as cooling and heating fluids. Therefore, it is essential to have an optimal design of minichannels. For this purpose, a square channel with a cylinder in the center connected to wavy fins at various concentrations of an Al2O3 nanofluid is simulated using the finite volume method (FVM). Moreover, central composite design (CCD) is used as a method of design of experiment (DOE) to study the effects of three input variables, namely the cylinder diameter, channel width, and fin radius on the convective heat transfer and pumping power. The impacts of the linear term, together with those of the square and interactive on the response variables are determined using Pareto and main effects plots by an ANOVA. The non-dominated sorting genetic algorithm-II (NSGA-II), along with the response surface methodology (RSM) is applied to achieve the optimal configuration and nanofluid concentration. The results indicate that the effect of the channel width and cylinder diameter enhances about 21% and 18% by increasing the concentration from 0% to 5%. On the other hand, the pumping power response is not sensitive to the nanofluid concentration. Besides, the channel width has the highest and lowest effect on the heat transfer coefficient (HTC) and pumping power, respectively. The optimization for a concentration of 3% indicates that in Re = 500 when the geometry is optimized, the HTC enhances by almost 9%, while the pumping power increases by about 18%. In contrast, by increasing the concentration from 1% to 3%, merely an 8% enhancement in HTC is obtained, while the pumping power intensifies around 60%.

Experimental Investigations of Enhanced Micro Structured Heat Sinks

In this research, we focus on the performance of heat sink, new configurations of the micro heat sink with comprises of pinned copper pieces of appropriate dimensions have been proposed. Dozens of different shapes micro heat sinks have been manufactured from brass using Laser technique. These heat sinks have been coupled individually with a simulated electronic circuit including a power transistor to freely dissipate the generated heat. Bulk temperatures of heat sink and the power transistor have been measured using a thermal camera. The results showed that, in general, the finned heat sink of either configuration augments heat transfer compared with smooth one. It is found that the maximum percentage reductions in temperature of the transistor are demonstrated with two uncommon configurations, namely the leaves-shaped fin (LSF) 9.352% and the drop-shaped fin (DSF) 9.353%. on the other hand, a staggered wavy fin (SWF) shows minimum percentage reduction in transistor temperature, 0.952%. It has been shown that through this research and by using several models of heat sink, the increase in surface area is not only the factor (major) to increase the heat transfer to the surrounding environment. This makes it possible to design fins with a smaller surface area but more heat dispersionIn this research, we focus on the performance of heat sink, new configurations of the micro heat sink with comprises of pinned copper pieces of appropriate dimensions have been proposed. Dozens of different shapes micro heat sinks have been manufactured from brass using Laser technique. These heat sinks have been coupled individually with a simulated electronic circuit including a power transistor to freely dissipate the generated heat. Bulk temperatures of heat sink and the power transistor have been measured using a thermal camera. The results showed that, in general, the finned heat sink of either configuration augments heat transfer compared with smooth one. It is found that the maximum percentage reductions in temperature of the transistor are demonstrated with two uncommon configurations, namely the leaves-shaped fin (LSF) 9.352% and the drop-shaped fin (DSF) 9.353%. on the other hand, a staggered wavy fin (SWF) shows minimum percentage reduction in transistor temperature, 0.952%. It has been shown that through this research and by using several models of heat sink, the increase in surface area is not only the factor (major) to increase the heat transfer to the surrounding environment. This makes it possible to design fins with a smaller surface area but more heat dispersion.

Thermal performance of a zig-zag channel formed by two wavy fins mounted with vortex generators

Wavy fins and vortex generators can separately enhance the thermal performance of heat exchangers. A novel combination of wavy fins and vortex generators is proposed in the present study to optimize the thermal performance of heat exchangers. The effects of the longitudinal vortices and attack angle of the vortex generators on the thermal performance of the novel combination are numerically studied. The longitudinal vortices are strengthened and weakened when the fluid flows over the crests and troughs of the bottom wall, respectively. The heat transfer on the pressure sides of both top and bottom wall surfaces is significantly larger than that on the corresponding suction sides. There is an optimal attack angle of 60°, which can provide the best heat transfer performance with a maximum 31.5% increase in the Nusselt number with only a 23.4% increase in the friction factor. The maximum thermal performance factor can be up to 1.23 with the optimal attack angle. Correlations for Nu and f are reported for both laminar and turbulent flows.

Exergy and energy performance for wavy fin radiator with a new coolant of various shape nanoparticle-based hybrid nanofluids

Energetic and exergetic performance for an automotive radiator with wavy fin configuration has been investigated and compared for water-based 1% vol. fraction of hybrid nanofluids of different shapes of nanoparticles, i.e., spherical (Al2O3) and cylindrical (CNT), spherical (Al2O3) and platelet (graphene) shapes at 15l pm flow rate. Effects of effectiveness, heat transfer rate and pressure drop, as well as exergy loss, entropy generation, second law efficiency with steady-state coolant flow rate, hybrid nanofluid vol. fractions and air velocity are discussed well. Results show that energetic–exergetic performances are enhanced by using the hybrid nanofluid of different shapes of nanoparticles. Nanoparticles of spherical (Al2O3) and cylindrical (CNT)-based hybrid nanofluid show the decrement in performance within the study. Nanoparticles of different shapes have been delivered a promising effect on both parameters (irreversibility and second law efficiency) and are increases with coolant flow rate. Spherical and platelet-shaped nanoparticle-based hybrid nanofluid has 2.94% 1.73% and 1.62% of higher effectiveness, entropy change in the air and coolants, respectively, compared to hybrid nanofluid of spherical and cylindrical shape nanoparticles. This inspection divulges on the particle shape, which has a critical consequence on the accomplishment of hybrid nanofluids in automotive radiators and the application of spherical and graphene shape nanoparticle-based hybrid nanofluid is more effective to enhance the radiator performance.

Experimental investigation of effect of different tube row-numbers, fin pitches and operating conditions on thermal and hydraulic performances of louvered and wavy finned heat exchangers

Heat exchangers are used in air conditioners, heat pumps, marine, land and air vehicles, refrigeration systems, thermal and nuclear power plants, etc. Increasing heat transfer capacity of a heat exchanger means that the volume of the heat exchanger and the material used will be reduced. Besides, effects of some geometric parameters on heat transfer and pressure drop are more complex depending on the fin structure in fin and tube heat exchangers. In this study, three of the most dominant parameters affecting the thermal-hydraulic performance of a finned and tube heat exchanger were experimentally investigated. These are fin-type (louvered and wavy fins), fin pitch and number of tube-rows. The intermittent geometric structures of louvered fins break growing of the boundary layer and reduce its thickness yielding heat transfer enhancement. On the other hand, wavy fins cause an increase in the heat transfer area due to its large flow length and create instabilities in the flow due to flow separations increasing the heat transfer coefficient. In the present study, specifically five louvered finned and three wavy finned and round tube heat exchanger prototypes were manufactured. Heat transfer and pressure drop experiments of these heat exchangers were performed at a wind tunnel in a conditioned room. Heat transfer and pressure drop characteristics were presented as heat transfer coefficient ho, Stanton number St, Nusselt number Nu, dimensionless pressure drop coefficient Cp, Colburn-j factor, Fanning friction factor f, jlouver/jwavy, flouver/fwavy, j/f1/3 ratios and JF factor. The results were examined from the point of heat transfer and pressure drop mechanisms of louvered and wavy fins for the different number of tube-rows, fin pitches and air inlet velocities. It is found that Colburn-j factors and Fanning friction f factors of the LFRTHXs are higher than those of the WFRTHXs for all the studied cases. Colburn-j factors of the LFRTHXs are higher by 16.4–6.9%, 28.5–18.3% and 25–11.7% than those of the WFRTHXs for the cases of two tube-rows, three tube-rows and four tube-rows, respectively. On the other hand, pressure drops of the LFRTHXs are significantly higher than those of WFRTHXs. However, the thermal-hydraulic performances of the LFRTHXs are still higher than that of WFRTHXs. The thermal-hydraulic performance criteria j/f1/3 ratios of the LFRTHXs are higher by 9.6–4.1%, 22.1–16% and 16.8–7.4% than those of the WFRTHXs for the cases of two tube-rows, three tube-rows and four tube-rows, respectively.

Improving air-side heat transfer performance in air-cooled power plant condensers

One method to reduce water consumption in cooling towers for steam condensation is to use dry-cooled technologies with air as the heat rejection medium. These air-cooled systems are beneficial where water is unavailable or uneconomical, but typically result in lower power plant efficiencies. The present study investigates the application of an A-frame air-cooled condenser (ACC) with various air-side enhancements to increase dry-cooled plant performance to levels approaching wet-cooled plants. A computational model was developed to predict the air-cooled condenser performance during the summer (inlet air at 30 °C and 25% relative humidity), when air-cooled systems typically perform the worst. Parametric studies were conducted to identify optimal condenser geometries with smooth, wavy, and louvered fins. The segmented condenser model was integrated into Rankine cycle and combined cycle power plant models to determine the impact of various condenser fin geometries on overall cycle performance. While ACC designs with wavy or louvered fins improved the overall cycle efficiencies over the baseline case, it was found that a reduction in fin spacing of the conventional, smooth fins resulted in the largest improvement in cycle efficiency (1.14% increase for the Rankine cycle, and a 0.84% increase for the Combined cycle).

Effect of wavy fin usage on thermal performance of heat exchanger used in combi boilers

In this study, performance of a heat exchanger used in combi boilers was investigated numerically for different fin geometries. Analyses were performed at the boiler operation conditions. A commercial CFD software package, FLUENT, was used for numerical simulations. The 3-D steady-state turbulent flow field analysis was carried out and k-? model was preferred as the turbulence model. In the analysis, it was assumed that the heat transfer phenomenon occurred both by conduction and convection. Flat fin geometry was taken as a reference for the investigation. Variation of the heat transfer and pressure drop values for the wavy fin were compared with the reference geometry. The wave angle and wave radius were taken as the parameters for the wavy fins. For different fin geometries: the outlet temperaTure of the combustion gases, the heat transfer to the water, and the pressure drop were calculated and the results were presented. Compared with flat fin, average decrease for the outlet temperature of hot gases was obtained as 4 K and average increase for the heat transfer to the water was calculated as 0.68 W. On the other hand, the average pressure drop in the heat exchanger with wavy fins was about 70% higher than the flat fin.