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The prediction of critical velocity at instability threshold for shell and tube heat exchangers is important to avoid failure of tubes as a result of flow-induced vibrations due to water cross flow. The flow-induced vibration in finned tube heat exchangers is affected by various parameters such as fin height, fin pitch, fin material, tube array, pitch ratio, fin type, fluid velocity etc. In this paper, an experimental investigation of fluid elastic instability in shell and tube heat exchangers is carried out by subjecting normal square finned tube arrays of pitch ratio 1.79 to water cross flow.

The five tube arrays, namely plain array, two finned tube arrays with 3 fpi and 9 fpi fin density, and two finned tube arrays with 3 mm and 6 mm fin height are tested in the experimental test setup with water flow loop and vibration measurement system. The research objective is to evaluate the effect of fin density and fin height on the instability threshold. The critical velocity at instability threshold is determined to characterize the fluid elastic instability behavior of different tube arrays. The vortex shedding behavior of the tube arrays is also studied by determining Strouhal number corresponding to the small peaks before fluid elastic instability.

The fluid elastic instability behavior of the tube arrays was found to be the function of fin tube parameters. The experimental results indicate that an increase in fin density and fin height results in delaying the instability threshold for finned tube arrays. It is also observed that critical velocity at instability is increased for finned tube arrays compared to plain tube arrays of the same pitch ratio. The design modifications in the outer box have resulted in further reduction in the natural frequency. This enabled to reach clear instability for all the five-tube arrays.

The research data add the value to the present body of knowledge by knowing the effect of fin height and fin density on the fluid elastic instability threshold of normal square finned tube arrays subjected to water cross flow.

Predicting the critical velocity is crucial at the instability threshold for shell and tube heat exchangers in order to prevent tube failure due to vibrations. In this study, the vibration response of an aluminum tube bundle subjected to water cross flow was analyzed experimentally. Aluminum tubes are preferred over steel tubes because of aluminum tubes' excellent corrosion resistance, ease of manufacture, and high thermal efficiency.

The fluid elastic instability and vortex shedding mechanisms in a finned tube array of aluminum tubes with a base tube diameter of 19.05 mm and pitch of 34 mm were investigated. The current study considers parallel triangular finned tube arrays with fin heights of 3 mm and 6 mm with a uniform fin thickness and fin pitch. The plain tube array was tested to compare the finned tube array results. The tube vibration response was measured using an accelerometer mounted on the middle tube of the third row. In order to define the fluid elastic instability behavior of various tube arrays, the critical velocity at the instability threshold is measured. By finding the Strouhal number at the small peaks before instability, the vortex shedding behavior of the tube arrays is examined.

The results reveal that the critical velocity at instability for coarse finned tube arrays increases as the fin height increases. The effect of the tube material is evaluated by comparing the results with those previously reported for parallel triangular tube arrays made of steel. Finally, the occurrence of vortex shedding in a tube array is confirmed based on the Reynolds number and Strouhal number relationship. The instability constant K for the plain tube array of steel and aluminum material are 4.97 and 4.87, respectively.

This paper provides the research findings on the effect of fin height on coarse density finned tube array. This will add substantial knowledge to the literature in the field of fluid elastic instability and vortex shedding, which is needed for the safe functioning of shell and tube heat exchangers.

The purpose of this paper is to present investigations on the significant influence of the tube material and fin density on fluid elastic instability and vortex shedding in a parallel triangular finned tube array subjected to water cross flow.

The experiment was conducted on finned tube arrays with a fin height of 6 mm and fin density of 3 fins per inch (fpi) and 9 fpi. A dedicated setup has been developed to examine fluid elastic instability and vortex shedding. Nine parallel triangular tube arrays with a pitch to tube diameter ratio of 1.78 were considered. The plain tube arrays, coarse finned tube arrays and fine finned tube arrays each of steel, copper and aluminium materials were tested. Plain tube arrays were tested to compare the results of the finned tube arrays having an effective tube diameter same as that of the plain tube.

A significant effect of fin density and tube material with a variable mass damping parameter was observed on the instability threshold. In the parallel triangular finned tube array subjected to water cross flow, a delay in the instability threshold was observed with an increase in fin density. For steel and aluminium tube arrays, the natural frequency is 9.77 Hz and 10.38 Hz, which is close to each other, whereas natural frequency of the copper tubes is 7.40 Hz. The Connors’ stability constant K for steel and aluminium tube arrays is 4.78 and 4.87, respectively, whereas it is 5.76 for copper tube arrays, which increases considerably compared to aluminum and steel tube arrays. The existence of vortex shedding is confirmed by comparing experimental results with Owen’s hypothesis and the Strouhal number and Reynolds number relationship.

This paper’s results contribute to understand the effect of tube materials and fin density on fluid elastic instability threshold of finned tube arrays subjected to water cross flow.

This paper aims to analyze the effect of fin geometry on mechanisms of flow induced vibration. Finned tube arrays are used in a heat exchanger to increase its efficiency. Therefore, it is necessary to investigate the effect of geometric parameters of the fin fluid elastic instability and vortex shedding. In this paper, the effect of fin height, fin density and tube pitch ratio for parallel triangular tube array on fluid elastic instability and vortex shedding is analyzed.

Experimental analysis was carried out on a parallel triangular finned tube array with a pitch ratio of 1.79 subjected to water crossflow. The experimentation aims to study fluid elastic instability and vortex-induced vibration mechanism responsible for flow induced vibration for finned tube array. A fully flexible finned tube array of the copper tube was used with its base diameter of 19.05 mm and thickness of 2 mm. Over the tube surface, crimped fins of height 6 mm and the same material are welded spirally with fin density 8.47 mm and 2.82 mm. Experimental analysis was carried out on a test setup developed for the same. The results obtained for the finned tube array were compared with those for the plain tube array with the same base tube diameter.

For parallel triangular tube array of copper material, test results show that critical velocity increases with an increase in fin pitch density for low pitch tube array. Before the occurrence of instability, the rate of growth in tube vibrations is high for plain tubes compared to that with fin tubes. The results based on Owen’s hypothesis show vortex shedding before the occurrence of fluid elastic instability. The effect of fin geometry on vortex-induced forces is analyzed. For the tube array pattern understudy, the values of Conner’s constant K for coarse fin-tube and fine fin tube array are obtained, respectively, 6.14 and 7.25.

This paper fulfills the need for research on the effect of fin geometry on fluid elastic instability and Vortex shedding on a tube array subjected to water cross flow when the pitch ratio is less than two, i.e. with a low pitch ratio.

To make the finned exchanger light and compact, the design of optimized fins has become increasingly important nowadays. The purpose of this paper is to present a numerical investigation on forced convection in a horizontal parallel plate channel with inline transverse fins on channel walls.

Through the use of a stream function vorticity transformation, solution of the transformed governing equations for the system is obtained using the control‐volume method with non‐uniform grid. The extrapolated‐Jacobi scheme was used to solve the finite‐difference equations.

For fins with fixed fin volumes, the array fins of optimum aspect ratios which dissipate maximum heat transfer in a parallel‐plate channel are obtained. For these optimum fins, it shows that the first fin is the shortest and the height of the rest of fins increases along the downstream direction of the channel. In addition, the optimum aspect ratio of a fin increases with Reynolds number and fin spacing but decreases with thermal conductivity ratio and entrance length with other parameters fixed.

This is the first paper devoted to the exploration of the optimized fin array in a forced convective channel, considering heat conduction in the fins and heat convection in the fluid simultaneously.

The paper aims to investigate the influence of the angle of inclination on mixed convection heat transfer from rectangular plated shrouded fin array computationally. This study has got applications in the various thermal field such as cooling, solar thermal and so on.

A computational study is made to evaluate the thermal performance in an inclined channel.

Increase in clearance from 0.01 to 0.25 results in an increase of local Nusselt number by is as high as 15% near the exit. At a higher value of Gr with an increase in C* from 0.10, Nu is found to increase by 5.5%. Increase in Gr by 1.37 times results in enhancement of Nu by a maximum of 25-30%. Around 10% increase in overall Nu value is observed with an increase in inclination (i.e. from 30° to 60°).

This study has got applications in the various thermal field such as cooling, solar thermal and so on.

Entry region mixed convection in a shrouded inclined finned channel is performed.

A detailed comparative study of the heat transfer augmentation of in‐tube flows accounting for an array of equally‐spaced plate fins attached at the outer surface is undertaken. The aim of the paper is to critically examine the thermal response of this kind of finned tubes to three different mathematical models: a complete 3‐D distributed model, a reduced 2‐D distributed/lumped hybrid model and two largely simplified 1‐D lumped models. For the three models tested, the computed results consistently demonstrate that the simplest 1‐D lumped model, with embedded arithmetic spatial‐ and geometric spatial‐means of the angular external convective coefficients provide dependable algebraic estimates of the actual heat transfer provided by the 3‐D distributed model with its indispensable finite‐difference solution. Further, an arithmetic mean of the maximum and minimum heat transfer supplied by the 1‐D lumped model delivered results that match those computed with the 3‐D distributed model. The most important steps of the mathematical derivations have been highlighted. A representative group of thermal performance diagrams is explained with the intent to assist engineers engaged in the thermal design of externally finned tubes of compact heat exchangers and HVAC devices.

The purpose of this paper is to present a way to determine the optimum values of design parameters in a cylindrical heat sink with branched fins. Investigations into the effect of design parameters, such as the number of fins, length of fin, height of fin and outer diameter of the heat sink on heat transfer are reported here. In this analysis, branch angle (α = 10°) is considered.

The Taguchi method, a powerful tool to design optimization, is applied for the tests and standard L9 orthogonal array with three factors, and three levels for each factor are selected. Nine test samples are analyzed in which the total heat transfer rate for each test sample is found. Contribution ratios for each parameter are also found. The results obtained from this analysis are used to find the optimum design parameter values relating to the heat sink performance.

The optimum design parameters are analyzed in this paper. The reliability of the optimum test samples is verified. Also, the variation of the average heat transfer rate of optimum sample is reported when it is compared with the reference sample.

Effective design of a cylindrical heat sink has been reported for cooling light-emitting diode (LED) lights, which have recently attracted the attention of the illumination industry. In this analysis, the contribution ratios have an important role to set out the performance characteristics of a heat sink.

The reliability of the optimum test samples is verified. Also, the variation of the average heat transfer rate of optimum sample is reported when it is compared with the reference sample.

The purpose of this paper is to enhance the heat transfer and thermal performance in the trailing edge region of the vane with vortex generators (VGs).

This numerical study presents the enhancement of thermal performance in the trailing part of a gas turbine blade. In the trailing part, generally, pin fins are used either in staggered or in-line arrangements to enhance the heat transfer. In this study, based on the idea from heat exchangers, pin fins are combined with VGs. A pair of VGs is embedded in the boundary layer upstream of each pin fin in the first row of the pin fin array having an in-line configuration. The effects of the VG angle relative to the streamwise direction and streamwise distance between the pin fin and VGs are investigated at various Reynolds numbers.

The results indicated that the endwall heat transfer is enhanced with the addition of VGs and the heat transfer from the surfaces of the pin fins. The level of heat transfer enhancement compared to the case without VGs is more significant at high Reynolds number. The surfaces of the VGs also show a significant amount of heat transfer. Study of the angle of the attack suggested that a high angle of attack is more appropriate for pin fin cooling enhancement whereas an intermediate gap between the VGs and pin fins shows considerable improvement of thermal performance compared to the small and large gaps. The phenomenon of heat transfer augmentation with the VGs is demonstrated by the flow field. It shows that the enhancement of heat transfer is governed by the mixing of the flow as a result of the interaction of vortices generated by the VGs and pin fins.

VGs are used to disturb the thermal boundary layer. It shows that heat transfer is augmented as a result of the interaction of vortices associated with VGs and pin fins.

The purpose of this paper is to study the thermal and flow characteristics of a single annually finned-tube condenser. The velocity and the temperature field inside the fin channel are revealed. Changes of the heat transfer and the flow resistance for typical fin configurations are analyzed. The optimal combinations of the fin dimension in terms of the enhancement of heat transfer are suggested.

The problem has been numerically investigated with the FLUENT software. K-ɛ model is applied in the solution of the turbulent cases. The local and the average feature of the thermal performance and the friction factor are determined. Furthermore, the effect of the fin spacing, the fin height, and the fin thickness on the heat transfer and the flow resistance are verified.

The numerical results reveal that the fin spacing is the most influential factor of all fin dimensions not only to the heat transfer but also to the flow resistance. Both the heat transfer and the flow resistance are compared with those related data available in the public literature. On the other hand, the fin height and the fin thickness affect the heat transfer of the condenser in a much less significant way in comparison to that of the fin spacing.

This paper provides some meaningful information of the fin-dimensional effect on the heat transfer and the flow resistance for a single finned tube condenser. For such kind of heat exchanger, the heat transfer coefficient, the friction factor, and the heat transfer amount per unit length tube are all important to describe the performance feature.