Fin System Research Articles

The experimental study of dehumidification and regeneration processes in a fin and tube liquid desiccant system

Significant focus has been placed on improving Indoor Air Quality (IAQ) due to the emergence of the large-scale severe acute respiratory syndrome (SARS) virus epidemic in the air conditioning system of buildings. There is also a need for an adequate air ventilation system that balances energy needs with air quality. This led to the discovery of liquid desiccants which have the ability to enhance air quality and lower primary energy usage as an alternative to the standard air dehumidification technology. Therefore, this study was conducted to investigate the dehumidification and regeneration processes in a Fin and tube liquid desiccant system. This involved flowing air horizontally while the ionic liquid flowed through the cooling or heating coil vertically downward to create a cross-flow fin and tube configuration. In the testing process, we obtained measurements of relative humidity and dry bulb temperature inlet and outlet from ducting by varying the input parameters. Moreover, the differential humidity ratio of the inlet and output process for the dehumidification and regeneration was observed to be essential for the dehumidifier performance indices. The experimental result showed that the system absorbed a humidity ratio of 5.5 g/kg during the dehumidification process and released 10.7 g/kg during regeneration.

Thermo-Hydraulic Optimization of Shell and Externally Finned Tubes Heat Exchanger by the Thermal Efficiency Method and Second Law of Thermodynamics

The application aims to determine the thermal and hydraulic performance of externally finned, counter-flow, Shell, and Tube Heat Exchangers (STHE). The application refers to the cooling of machine oil flowing in the annular region, including non-spherical cylindrical nanoparticles of Boehmite Alumina. The oil inlet temperature is equal to 80 °C. Sea water is a coolant with an inlet temperature of 20°C. The main parameter in the optimization process is the number of finned tubes used for oil cooling. Another optimization factor is the number of heat exchanger units connected by hairpin. The number of fins per tube is fixed, equal to 34. The oil flow is set and equal to 4.0 kg/s. The inlet water flow varies, with a maximum flow of 5.0 kg/s. The quantities determined for analysis are: the thermal effectiveness, the actual and maximum heat transfer rates, the pressure drops caused in the tubes and by the flow in the annular region and fin system, the thermal and viscous irreversibilities, and the fluid outlet temperatures, and the thermodynamic Bejan number. It was determined that increasing the number of finned tubes from two to six tubes leads to better thermal and hydrodynamic performance. That is, it produces a favorable cost-benefit, to the detriment of the high viscous dissipation caused by the oil in the annular region. As an object of analysis, the inclusion of nanoparticles showed a significant improvement in thermal performance and an increase in viscous dissipation, with a slight decline in the Bejan number.

Implementation of Ceiling Fin to Prevent the Spread of Airborne Pathogens by Buoyancy Effect

Physical barriers such as partitions can reduce airborne infection by preventing aerosol or droplets exhaled by one person from entering the breathing zone of another. However, if buoyancy effect occurred in a natural room, airborne pathogens rise vertically and spread horizontally. So, this study suggested ceiling fin system to prevent the spread of airborne pathogens due to buoyancy effect and investigated the effect of the ceiling fins in preventing the spread of airborne pathogens by STAR-CCM+ (computational fluid dynamics software). As the results of the study, the ceiling fins prevented the airflow recirculation around the ceiling. Also, implementation of ceiling fins reduced airborne pathogen concentrations (passive scalar concentrations of the simulation model) not only at breathing zone but also in the entire room by 14% and 11.7% respectively. These results indicate that implement of the ceiling fins to delay in spread and mixing of airborne pathogens in a room.

Performance of solar adsorption cooling system with internal finned vacuum tube bed

Aiming to improve the performance of the solar adsorption cooling system using the silica gel-water as the working pair, a series of fin-enhanced vacuum tube bed have been developed and tested experimentally. The characteristics of the system were analyzed as the fin number changed between zero to eight in the bed. It is revealed that longer time was needed for the preheating and desorption of the bed in a cycle because of the increase of the heat capacity of finned tube bed. Nevertheless, the fast heat transfer of the finned tube has resulted in a significant reduction of the pre-cooling time of the bed, which usually took the biggest part in the whole cycle time originally. The comprehensive result was the cycle time of the solar adsorption cooling system diminished, and the general performance of the system was improved. As evaluated under the criterion of the specific cooling power (SCP), it is found that the SCP 2 of the finned system, which is defined by the cycle time, increased 37.4%–80.7% in comparison to the situation of the smooth tube bed. On the other hand, analyzing the coefficient of performance (COP) of the system has revealed that not always the more the internal fins, the better the performance result. The experimental results told us that the COP of the system reached the optimum as the fin number was equal to four. Over enhanced tube bed caused the performance of the adsorption cooling system to deteriorate.

Dynamic analysis of the sinusoidal actuation of a flexible fin for paired fin propulsion

In this research, the sinusoidal actuation of a flexible fin for median and/or paired fin propulsion is studied. A prototype of an underwater robot is built, and the computer-aided engineering simulation method is used for the transmission system of the flexible fin. The fin ray at the end of the trajectory and the crankshaft drive the parameters as a function of the fin ray output parameters. Given the fin and the fin surface motion for the coupled simulation analysis, the flexible fin surface and the fin sinusoidal oscillation are studied. The deformation of the fin surface is established outside the edge wave trajectory equation of motion. The equations of motion are verified by simulation. The single fin wave model is solved with the computational fluid dynamics method, and the hydrodynamic performance of the fin surface is obtained. Using the dynamic mesh technique, the complex large fluctuation motion of the fin surface is solved. With different amplitudes and periods of the fin wave as the input parameters, a simulation of the fin wave propulsion is conducted, and the relationship between the fin wave propulsion force and the fin wave resistance is calculated. The correctness of the simulation results of the sinusoidal fixed wave of the fin surface is verified by a fin wave ink experiment.

Adaptive backstepping control for ship nonlinear active fin system based on disturbance observer and neural network

<span>Adaptive backstepping control based on disturbance observer and neural network for ship nonlinear active fin system is proposed. One disturbance observer is given to observe the disturbances of the system, by this way, the response time is shorten and the negative impact of disturbance and uncertain elements of the system is reduced. In addition, radial basic function neural network (RBFNN) is proposed to approach the unknown elements in the ship nonlinear active fin system, therefor the system can obtain good roll reduction effectiveness and overcome the uncertainties of the model, the designed controller can maintain the ship roll angle at desired value. Finally, the simulation results are given for a supply vessel to verify the successfulness of the proposed controller.</span>

A fast dynamic model for a large scale heat pipe embedded latent heat thermal energy storage system for optimal sizing and control

One of the challenges to design and control phase change material (PCM) based latent heat thermal energy storage (LHTES) systems is to develop fast models to accurately represent their transient and nonlinear behaviors. In this paper, a fast explicit modeling approach for a multi-dimensional finned PCM system, called alternating front propagating, is proposed based on the concept of the alternating-direction implicit algorithm for multi-dimensional parabolic and elliptic differential equations. The proposed modeling method is employed to develop a fast explicit dynamic model for a large scale LHTES system, whose heat transfer is enhanced by imbedded circular finned heat pipes. The developed fast model has negligible computational cost and is of sufficient accuracy compared to high-fidelity numerical solutions. The fast explicit model of the LHTES system was employed in a model predictive control framework to determine the HTF flowrate so that its outlet temperature meets a target value. The controlled HTF flowrate can increase the usage efficiency of the stored heat in a LHTES system.

Metal foam and fin implementation into a triple concentric tube heat exchanger over melting evolution

It is believed that it is going to be a sizeable mismatch between supply and demand when it comes to renewable resources. Lately, researchers are on course to compensate for the unpredictabilityof such resources by the employment of phase change materials (PCMs). Having multiple advantages, PCMs generally suffer from inadequate thermal conductivity which causes prolonged transition procedures. To tackle this issue, this study is fixated on two parameterswhich are linked to fins addition and porous media incorporation in a melting process within a triple concentric tube heat exchanger (TCTHX). The results provided by multiple cases underlined the significance of natural convection in the bare system, although finned and copper-metal-foam cases outshine buoyancy forces by roughly 45% and 97%, respectively. Material is a major determent when it comes to the selection of porous media as Al2O3 registered the weakest performance among SiC, Ni and Cu, however, it managed to speed up the process by 75% which still is much higher than the finned system, implying that porous media is of higher priority over fins. The best scenario transpiredwhile fins and copper metal foam were integrated as 26% and 97% soars in efficacy have been obtained compared to individual incorporation of porous media and fins, respectively.

Heat Transfer Enhancement of Latent Heat Storage Using Novel Quadruple Helical Fins

A novel fin configuration which is of quadruple helical geometry is proposed to augment the heat transfer performance of latent heat thermal energy storage systems. The thermal characteristics of paraffin wax under the influence of quadruple helical fins and longitudinal fins are analyzed through three-dimensional numerical formulation employing enthalpy-porosity approach. The impact of these two fin geometries on the natural convection during melting is also investigated. The numerical results are validated against experimental results. The quadruple helical fins are found to be superior to conventional longitudinal fins in accelerating phase change rates as they provide higher heat transfer surface despite occupying same volume. Hence, the melting time was reduced by 85% with quadruple helical fins as compared to system without fins and longitudinal fins could exhibit 80% reduction in melting time. The reduction in solidification time is found to be 68% (quadruple fins) and 63% (longitudinal fins). Further, quadruple fin arrangement can generate vortex flow in liquid phase change material during melting and hence, enhanced natural convection is observed when compared to longitudinal fin system. The role of heat transfer fluid in altering the phase change rate is pronounced only in the finned systems.

Numerical Simulation of Solid and Porous Fins’ Impact on Heat Transfer Performance in a Differentially Heated Chamber

The development of different industrial fields, including mechanical and power engineering and electronics, demands the augmentation of heat transfer in engineering devices. Such enhancement can be achieved by adding extended heat transfer surfaces to the heated walls or heat-generating elements. This investigation is devoted to the numerical analysis of natural convective energy transport in a differentially heated chamber with isothermal vertical walls and a fin system mounted on the heated wall. The developed in-house computational code has been comprehensively validated. The Forchheimer–Brinkman extended Darcy model has been employed for the numerical simulation of transport phenomena in a porous material. The partial differential equations written, employing non-primitive variables, have been worked out by the finite difference technique. Analysis has been performed for solid and porous fins with various fin materials, amounts and heights. It has been revealed that porous fins provide a very good technique for the intensification of energy removal from heated surfaces.

The Experimental Study of Dehumidification and Regeneration Processes in a Fin and Tube Liquid Desiccant System

The Experimental Study of Dehumidification and Regeneration Processes in a Fin and Tube Liquid Desiccant System

Control of Ship Roll and Yaw Angles During Turning Motion

The aim of this paper is Ships are exposed to assorted hydrodynamic forces originating from internal and external influences. The adverse effect of rolling caused by turning motion should be reduced with anti-rolling systems, to ensure safe navigation. If this effect is not eliminated, it may prevent the ship from keeping its course safely. In this study, fin stabilizer system the computational analysis of the roll motion formed by the turning motion and wave effect is included in fin stabilizer system. The rudder motion that allows the ship to have the desired maneuvering angle; calculations of the fin system, which decreases the excessive roll moment, and the roll motion caused by these two effects are examined using MATLAB software. The analysis period has been determined as 300 seconds, which is the time to reach the desired turning angle of the ship. Linear quadratic tracking (LQT) algorithm has been used to solve partially unknown continuous-time problems such as roll motion in this study.

Cyber-physical aerodynamic shape optimization of a tall building in a wind tunnel using an active fin system

This study explores the use of a cyber-physical systems (CPS) framework for the design and optimization of the aerodynamics of a tall building through aeroelastic boundary layer wind tunnel (BLWT) testing. The framework is a fully-automated combination of traditional experimental wind tunnel testing with numerical optimization strategies to evaluate a wide range of candidate designs both accurately and quickly. In this study, candidate designs are achieved through the physical adjustment of the aerodynamic shape of a multi-degree-of-freedom (MDOF) aeroelastic tall building model. BLWT testing is carried out at the University of Florida Natural Hazard Engineering Research Infrastructure (NHERI) Experimental Facility (EF). The specimen is equipped with an actuation system consisting of a series of individually-controllable slotted fins comprising an active fin system (AFS), which enable precise modifications of the aerodynamic shape of the envelope. The wind-induced building response of the specimen is directly captured using a series of accelerometers and laser displacement sensors. A stochastic optimization algorithm is then employed in the aerodynamic CPS framework to evaluate the fitness of each candidate design based on specified performance criterion related to either occupant comfort or building drift. Optimization results indicate that the CPS framework can reliably achieve the optimal solution which minimizes the response (i.e., horizontal accelerations and lateral displacements) of the aeroelastic specimen.

Prediction of Heat-Generation and Electromagnetic Parameters from Temperature Response in Porous Fins

The application of combined electric and magnetic fields is proposed for better heat transfer enhancement in a porous fin system. An inverse estimation technique is established to simultaneously determine the interior thermal energy production and strengths of electrical and magnetic fields, by solely using the surface temperature field. At first, verified direct solutions based on the fourth-order Runge–Kutta method are obtained for the computation of the temperature field, and then three unidentified parameters are estimated using the inverse procedure supported by the Artificial Bee Colony (ABC) algorithm. The corresponding analytical solution is evaluated using the differential transformation method. The existing investigation demonstrates that even though various parametric groups sustain a particular thermal field, amongst them, the nearly unique value of the thermomagnetic field governs the heat transport phenomena. Additionally, the joint interaction between the electric field and thermal-energy-generation parameter is accountable for the observed temperature field. In spite of the effect of random noise levels within +/− 11%, the ABC-based inverse solution technique is found to establish the thermal criteria and to excellently reconstruct the given thermal field within a less than 1% error margin with respect to the ideal situation. For any case, 50 iterations of ABC are observed to be satisfactory. For fulfilling the desired rate of thermal energy transfer from porous fins, the present prediction scheme is suggested to be beneficial in properly adjusting the electrical and magnetic fields along with the unknown state of thermal energy production.

Estimation Technique of Minimum Energy Required for Complete Deployment of Folded Fin Under Gust Requirement (II): Considering Time Constraint

A previously developed estimation technique, of the minimum energy required for complete fin deployment under an operational requirement of gust speed, was modified to consider time consumed for fin unfolding as an additional requirement, which might lead to an increase of the required energy. Some modifications were made such as non-zero kinetic energy of unfolding fin when completely deployed and its monotonically increasing angular speed during unfolding motion having a profile of square-root function which helped to properly evaluate elapsed time for fin unfolding and to combine the additional time constraint with the fin folding motion equation including external moments of aerodynamics, gravitation, and friction, while, in the previous study, zero energy and bell-shaped speed profile had been used. Demonstrations of this estimation technique considering the time constraint additionally to the gust speed requirement were carried out with the same unfolding fin system and torque profiles used in the previous study and showed that unfolding systems equipped with energy estimated by this technique met all the given gust requirement and time constraint, irrespective of their torque profile, in terms of elapsed time for fin unfolding and allowable wind speed denoting the maximum speed of gust against which in every direction fin could deploy.

Numerical and Experimental Analysis in the Production of a Solar Still

In this work, a numerical and experimental study is shown for a single slope solar still with internal reflectors and a finned system at the absorber plate, in it 30 experimental tests were made with 3 L of water, for which temperature measurements were obtained, mainly at the glass cover, the absorber plate, fluid and at the environment, as well as the incident solar radiation, the experimental information was obtained through ADAMS modules, type K thermocouples and a pyranometer, besides the distillate volume was measured with measuring cylinders. From the experimental data, a model was constructed to understand the effect of solar radiation and fluid temperature on distillate production. As a result, for this experiment a cubic function that describes de distillate volume behaviour was found, which only depends on the solar radiation and the official time, this equation has at least a 6% error on average regarding to the experimental distillate volume.

Numerical simulation of the unsteady aerodynamic loads on the tail fin in the vortex breakdown flow

This work presents numerical simulation results of the flow around an airbrake-tail fin system of an aircraft. In this research, airbrake location and deflection angles effects on the unsteady aero...

Entropy Analysis of a Simple Rectangular Radiating Fin for Space Applications

For growing interest in planetary exploration, it is substantial to study the utilization of energy for future-built planetary settlements, as energy resources are at a premium far away from earth. Entropy analysis is proposed as a suitable tool to study these systems, and make them energy efficient. Hence, a simple, purely radiating rectangular fin is studied by entropy generation analysis. The distribution of temperature and radiosity of the fin is first obtained by solving the governing heat transfer equation by second order finite difference numerical analysis. Using these data, the heat transfer and entropy generation of fin, fin-base, and the surrounding space is calculated. The effect of solar irradiation on the heat transfer of fin is also considered. The influence of pertinent, non-dimensional parameters on the total rate of entropy generated by the fin system is analyzed. Further, a correlation with these parameters is obtained for the total entropy generation.

A computational fluid dynamics study by conjugate heat transfer in OpenFOAM: A liquid cooling concept for high power electronics

A conjugate heat transfer (CHT) study of a liquid cooling heat exchanger is carried out using the open source computational fluid dynamics (CFD) library OpenFOAM. The heat exchanger was 3D printed using aluminium and experimentally verified by temperature probing and thermal imaging. The functionality of the heat exchanger in cooling localized heat sources is demonstrated. Three different turbulence models were utilized including k-ω shear stress transport (SST) model, the standard k-ε model and large-eddy simulation (LES). The numerical results indicate that the k-ω SST and LES models produced similar results in terms of flow structures and temperature levels while the k-ε model deviated from the two other models. The scalability of the heat exchanger was numerically demonstrated by comparing the flow uniformity by varying the inlet Reynolds number between 4960 and 14880. The conclusions of the paper consists of the following main results. (1) The numerical results indicate that the flow uniformity in the channels is noted to be affected by the flow structures before and after the fin system. (2) The simulated hot-spot temperatures were noted to be relatively sensitive to the predicted flow laminarization inside the channels. (3) The heat exchanger was shown to be functional and to maintain cool surface temperatures in the simulations and the experiments. Additionally, the used CHT solver in OpenFOAM is tested and verified in different ways.

A Parametric Method to Customize Surfboard and Stand Up Paddle Board Fins for Additive Manufacturing

At all levels of sporting competition, from recreational to elite, athletes desire products that improve their performance, comfort, safety, or enjoyment. Additive manufacturing, also known as 3D printing, provides a new method of producing sporting equipment that can be customized to the unique needs of an individual. This study examines the opportunity to produce surfboard and stand up paddle (SUP) board fins through 3D printing and details a parametric computer-aided design (CAD) system for surfers to modify the geometry of a surf fin in real-time. Specifically, the fin system, fin position on the board, cant, fin depth, sweep, base length, base foil profile, tip sharpness, tip thickness, as well as the overall dimensions can be modified using simple interactive controls that do not require any CAD experience. Indicative cost data was collected for ten virtual fins designed through this system intended for fused filament fabrication (FFF), selective laser sintering (SLS) and multi jet fusion (MJF) technologies. Two designs were 3D printed and trialled on a SUP board. The method of creating the parametric system is sufficiently detailed in order to be replicable and built upon by designers, with future research directions outlined in order to improve surfing performance and extend the well-established culture of experimentation within the sport.