Tube Side Pressure Drop Research Articles

Configuration Optimization of a Shell-and-Tube Heat Exchanger with Segmental Baffles Based on Combination of NSGAII and MOPSO Embedded Grouping Cooperative Coevolution Strategy

A design indicators prediction model using the Bell-Delaware method for a shell-and-tube heat exchanger with segmental baffles (STHX-SB) is constructed and validated by experiment. The average errors of heat transfer capacity and tube-side pressure drop are 8.52% and 7.92%, respectively, and the predicted weight is the same as the weight obtained by Solidworks commercial software, which indicates the model’s reliability. Parametric influences of the outside diameter of the heat dissipation tube, clearance between heat dissipation tubes, heat dissipation tube length, and tube bundle bypass flow clearance on heat transfer capacity per tube-side pressure drop and heat transfer capacity per weight are studied, and it indicates that whether the interaction between factors is considered or not, both heat transfer capacity per tube-side pressure drop and heat transfer capacity per weight are the most sensitive to outside diameter of heat dissipation tube and the least sensitive to heat dissipation tube length based on the Sobol’ method. To avoid falling into local optima due to algorithm convergence being too fast and to improve the reliability of solving complex optimization problems, Non-Dominated Sorted Genetic Algorithm II (NSGAII) and Multi-Objective Particle Swarm Optimization (MOPSO) embedded grouping cooperative coevolution (NSGAII-MOPSO-GCC) is proposed to optimize the studied four configuration parameters to maximize heat transfer capacity per tube-side pressure drop and heat transfer capacity per weight for STHX-SB, simultaneously. Compared with the original structure, heat transfer capacity per tube-side pressure drop and heat transfer capacity per weight of the chosen solutions separately increased by 57.66% and 4.63%, averagely, and in the optimization comparison of NSGAII, MOPSO, and NSGAII-MOPSO-GCC, NSGAII-MOPSO-GCC has the best performance, which shows that the proposed method is effective and feasible and can supply beneficial solutions and valuable guidance for heat exchanger design and improvement.

Prediction of heat transfer coefficient, pressure drop, and overall cost of double-pipe heat exchangers using the artificial neural network

Typically, success in the estimation of machine learning is expected to rise with increasing input parameters, whereas the noise issue may rarely arise owing to redundant input factors undesirably influencing the learning algorithm. The parameters such as overall heat transfer coefficient, pressure drop, and overall cost have been determined by two different artificial neural networks evaluated by a multi-layer perceptron model. Using the Levenberg-Marquardt training algorithm, in the first model input layer, a total of 10 input parameters ρ, np, k1, Re1, fi, Re2, fo, ns, P1 and P2 have been defined, while the second involves 8 input parameters by subtracting pumping powers from the first one, thus the noise issue has been investigated using unnecessary input parameters. Overall heat transfer coefficient, tube/annulus sides pressure drops, and overall cost have been estimated with deviations of 0.16%, 0.23%, 0.02%, and 0.003% via Model 1, 0.02%, 0.18%, 0.16%, and 0.15% via Model 2, respectively. Moreover, Model 1 results in the best mean squared errors for annulus side pressure drop and overall cost with the values of 2.54E-04 and 1.93E-04, correspondingly, whereas Model 2 yields the best values of 1.11E-04 and 1.90E-04 for overall heat transfer coefficient and tube side pressure drop, sequentially.

Multi-objective optimization of helical coil steam generator in high temperature gas reactors with genetic algorithm and response surface method

High temperature gas reactors (HTGRs) have broad prospects in industry. The helical coil steam generator, which plays an important role in energy conversion in HTGRs, is widely adopted due to its high thermal efficiency. However, the design and performance analysis for helical coil steam generators is a definitely tough job induced by its complex structure and operation conditions. In this paper, an innovative multi-objective optimization process was proposed to manage the key parameter design of steam generators in HTGRs. Firstly, the system response of steam generators is investigated. The sensitivity of geometric parameters on the steam generator thermal performance is obtained through the response surface methodology (RSM). Finally, the geometric parameters of steam generators are optimized using the genetic algorithm with the goal of a higher heat transfer coefficient and a lower tube side pressure drop. Compared with the original design pressure drop (1.19 MPa) and heat transfer coefficient (1.007 kW∙m−2∙K−1, the optimal solution obtained by multi-objective genetic algorithm (MOGA) decreases the pressure drop by 50.76% and improves the overall heat transfer coefficient by 15.00%. It shows that MOGA performs well in heat transfer optimization of steam generators in HTGRs.

Investigation on heat transfer and pressure drop correlations of R600a air-cooled finned tube evaporator for fridge

The correlations to predict heat transfer coefficient and friction pressure drop of finned tube evaporator for fridge were developed. Twelve straight finned tube evaporators with different structural parameters were tested under different working conditions. The range of Reynolds number in air side was 750 < Rea < 9500 and that in tube side was 1000 < Rer < 15000. The models of evaporator heat transfer coefficient, air side pressure drop and tube side pressure drop were established respectively. The physical dimensions and flow parameters on both sides of finned tube evaporator were considered in the models and their effects on heat transfer and flow characteristics were revealed. The single-phase heat transfer area ratio was introduced. The correlations for household refrigerator evaporators were obtained through a nonlinear fitting method based on 210 groups of experimental data. The mean absolute percentage deviation of the new heat transfer correlation was 10.68%. The mean absolute percentage deviations of the new air side and refrigerant side pressure drop correlations were 8.8% and 10.3%, respectively. The data comparison showed that the proposed correlations were reasonable and accurate enough to be used in practical application.

Experimental and CFD investigation of spiral tube heat exchanger

In this paper, the thermal, hydraulic and thermodynamic performances of heat exchanger with spiral coils are placed cascading on the cylindrical shaped shell inside the heat exchanger. Tube side pressure drop and exergy efficiency are considered as a hydraulic and thermo hydraulic performance whereas overall heat transfer coefficient (U), effectiveness are considered as thermal performance. The tube side flow rate varies from 2 to 6 lpm and shell has two flow rates 4 lpm and 10 lpm. Flow conditions are varied and conducted the experiment to find the best flow rate inside the spiral heat exchanger. From the experiment results effectiveness, nusselt number, prandtl number, heat transfer rate, overall heat transfer coefficient and exergy efficiency, to validate the outlet temperature CFD analysis were performed on various flow rates. The experiment results are good in agreement with CFD results. Shell side flow rate of 10 lpm gives higher efficiency for the different flow rates of tube side from 2 to 6 lpm.

An analytical method for spiral-wound heat exchanger: design and cost estimation considering temperature-dependent fluid properties

PurposeSpiral-wound heat exchangers (SWHEs) are widely used in different industries. In special applications, such as cryogenic (HEs), fluid properties may significantly depend on fluid temperature. This paper aims to present an analytical method for design and rating of SWHEs considering variable fluid properties with consistent shell geometry and single-phase fluid.Design/methodology/approachTo consider variations of fluid properties, the HE is divided into identical segments, and the fluid properties are assumed to be constant in each segment. Validation of the analytical method is accomplished by using three-dimensional numerical simulation with shear stress transport k-ω model, and the numerical model is verified by using the experimental data. Moreover, the HE cost is selected as the main criterion in obtaining the proper design, and the most affordable geometry is selected as the proper design.FindingsThe accuracy of different heat transfer and pressure drop correlations is investigated by comparing the analytical and numerical results. The average errors in the calculation of effectiveness, shell-side pressure drop and tube-side pressure drop using the analytical method are 2.1%, 13.9% and 13.3%, respectively. Moreover, the effect of five main geometrical parameters on the SWHE cost is investigated. The results indicate that the effect of longitudinal pitch ratio on the SWHE cost can be neglected, whereas other geometrical parameters have a significant impact on the total cost of the SWHE.Originality/valueThis work contains a versatile and low-cost analytical method to design and rating the SWHEs considering the variable fluid property with consistent shell geometry. The previous studies have introduced complex methods and have not considered the consistency of shell geometry.

Thermal-hydraulic analysis of water based ZrO2 nanofluids in segmental baffled shell and tube heat exchangers

Thermal-hydraulic characteristics of water based ZrO2 nanofluids has been investigated in a segmental baffled shell and tube heat exchanger in turbulent flow regime. The effect of Reynolds number, nanoparticle loading, mass-flow rate, and tube lay-out has been analysed on overall heat transfer coefficient. The effect of Reynolds number on the tube side pressure drop and convective heat coefficient have also been discussed. The effect of shell side mass-flow rate was also investigated on shell side heat transfer coefficient determined using Bell-Delaware method. The nanoparticle volume concentration is taken very low i. e. 0.2%, 0.4%, and 0.8%, respectively. The improvement in both tube side convective heat transfer coefficient and overall heat transfer coefficient has been observed. The maximum improvement in the convective heat transfer coefficient is found to be 14.1% for 0.8% ZrO2 nanofluids. However, the percentage enhancement in tube side pressure drop was higher than the percentage increment in the tube side heat transfer coefficient.

Effect of wired nails circular–rod inserts on tube side performance of shell and tube heat exchanger: Experimental study

In this paper, the thermal, hydraulic, and thermodynamic performances in a shell and tube heat exchanger fitted with wired-nails circular–cut rod inserts on tube side are investigated experimentally. Thermal performance is expressed in terms of overall heat transfer coefficient (U), effectiveness (ε), and number of transfer unit (NTU), while hydraulic and thermodynamic performances are expressed in tube-side pressure drop and exergy efficiency, respectively. The tube side flow rate of hot water varies from (13–18) LPM while a constant flow rate of cold water on the shell side (i.e. 18 LPM) is considered. The experiments are performed for two configurations of wired-nails circular–cut rod inserts with different numbers of nails, varied space between them, and five different configurations of insert distribution in tubes. Also pressure drop is measured and exergy analysis is performed. All data obtained is compared with the conventional plain tube heat exchanger. The experimental results reveal that the proposed inserts configurations have a significant improvement on heat exchanger thermal and thermodynamic performances and a drawback in hydraulic performance. Percentages augmentation in U, NTU, ε, and exergy efficiency are (210–280%), (132–149%), (185–224%), and (130–210%), respectively over the conventional design.

Optimization of Joule-Thomson cryocooler heat exchanger using one-dimensional numerical modeling

Steady state operation of the heat exchanger of a Joule-Thomson cryocooler is studied numerically through a one-dimensional model. Argon is used as the working fluid. The developed model is first verified using a cooler configuration that is studied extensively in the literature. Then the model is improved in several ways. A major mistake seen in many of the previous studies is related to the mismatch of the friction coefficient correlation and the conservation of momentum equation of the tube side flow. With the use of consistent correlations, the calculated tube side pressure drop turned out to be 81% smaller. Additionally, the effect of pressure dependency of enthalpy is considered in the energy conservation equation, resulting in 37% increase in the cooling power. Other improvements are; (i) use of Collins tubing friction correlation for the shell side, (ii) defining the exit pressure of the shell side as atmospheric pressure and calculating the inlet pressure from the pressure drop, (iii) determining the inlet temperature of shell side as saturation temperature at the calculated pressure, and (iv) defining the emissivity of the shield as a function of temperature. An optimization study is performed using the improved model with two objectives (maximization of the specific cooling power which allows decreasing flow rate and minimization of the shell side pressure drop which results in a decreased working temperature). Five design parameters (heat exchanger length, finned capillary inner diameter, fin pitch, fin length and fin thickness) are selected through a sensitivity analysis of all possible design parameters. The optimum geometry is obtained using grid search method to maximize the optimization function formed by a weighted sum of two contradicting objectives. The optimum geometry allows a decrease of the flow rate by 46% within the defined constraints. The final shell side pressure drop is decreased by 90%.

Steam Condensation and Tube-Side Heat Transfer of Titanium Corrugated Tubes

In the present study, two titanium corrugated tubes (22.2 mm outer diameter and 0.5 mm tube thickness) having widely different corrugation pitch (2.1 and 22.1 mm) and having the same corrugation depth of 0.2 mm were tested at the steam pressures (from 5 to 10 kPa) representative of an actual electric utility condenser. Small corrugation depth of 0.2 mm was chosen from the concern of tube-side fouling and sponge ball cleaning. Significant enhancement of condensation heat transfer is noted, especially for 2.1/0.2 tube. The heat transfer enhancement ratios are 4.0 and 2.76 at 5 and 10 kPa, respectively. The tube-side heat transfer enhancement ratios are 1.08 for the 2.1/0.2 tube and 1.03 for the 22.1/0.2 tube. The tube-side pressure drop penalty factors are 1.56 for the 2.1/0.2 tube and 1.07 for 22.1/0.2 tube. Tube-side heat transfer may be further enhanced by increasing the corrugation height. However, concerns on fouling or corrosion should also be considered.

Thermal design, rating and second law analysis of shell and tube condensers based on Taguchi optimization for waste heat recovery based thermal desalination plants

The present work discusses the design and selection of a shell and tube condenser used in Low Temperature Thermal Desalination (LTTD). To optimize the key geometrical and process parameters of the condenser with multiple parameters and levels, a design of an experiment approach using Taguchi method was chosen. An orthogonal array (OA) of 25 designs was selected for this study. The condenser was designed, analysed using HTRI software and the heat transfer area with respective tube side pressure drop were computed using the same, as these two objective functions determine the capital and running cost of the condenser. There was a complex trade off between the heat transfer area and pressure drop in the analysis, however second law analysis was worked out for determining the optimal heat transfer area vs pressure drop for condensing the required heat load.

Experimental tube-side pressure drop characteristics of FLNG spiral wound heat exchanger under sloshing conditions

In order to study the operation reliability of spiral wound heat exchangers (SWHEs) applied in floating liquefied natural gas (FLNG) offshore platforms, an experimental device of dual mixed refrigeration (DMR) and a six-DOF (degree of freedom) sloshing platform are constructed. The effects of yawing, pitching, heaving and surging motions on the pressure drop characteristics of SWHE are analyzed experimentally at different sloshing angles, periods and amplitudes. The results show that pressure drop characteristics of gas-phase mixed refrigerant are influenced much more significantly under sloshing conditions, compared with feed gas and liquid-phase mixed refrigerant. In addition, heaving and pitching motions have a larger influence on tube-side pressure drop characteristics than surging and yawing, under the same conditions.

Modelling and experimental validation for off-design performance of the helical heat exchanger with LMTD correction taken into account

Today the helical coil heat exchanger is being employed widely due to its dominant advantages. In this study, a mathematical model was established to predict off-design works of the helical heat exchanger. The model was based on the LMTD and e-NTU methods, where a LMTD correction factor was taken into account to increase accuracy. An experimental apparatus was set-up to validate the model. Results showed that errors of thermal duty, outlet hot fluid temperature, outlet cold fluid temperature, shell-side pressure drop, and tube-side pressure drop were respectively ±5%, ±1%, ±1%, ±5% and ±2%. Diagrams of dimensionless operating parameters and a regression function were also presented as design-maps, a fast calculator for usage in design and operation of the exchanger. The study is expected to be a good tool to estimate off-design conditions of the single-phase helical heat exchangers.

Investigating the effect of nanoparticle on thermo-economic optimization of fin and tube heat exchanger

In this paper, the effects of Al2O3 nanoparticles suspended in the water-based fluid on the thermo-economic properties of a fin and tube heat exchanger are studied using fast and elitism nondominated sorting genetic algorithm. Nine design parameters are selected as design parameters, and the total annual cost and effectiveness are considered as the two objective functions. First, the effect of nanoparticle on the total annual cost versus effectiveness is obtained at different cold side mass flow rates, and the results are compared with the base fluid. The results show that nanoparticles have a significant influence on the total annual cost and effectiveness in a lower cold side mass flow rates. Next, the heat exchanger volume versus effectiveness for the optimum points is measured at different cold side mass flow rates. It is demonstrated that, adding Al2O3 nanoparticle to the base fluid for the fixed value of effectiveness, decreases the heat exchanger volume, and this reduction is more significant in the lower mass flow rates. The pressure drop and total heat transfer surface area versus effectiveness for the optimum points are also obtained with and without nanoparticle. An increase in the tube side pressure drop is revealed in the nanofluid. In addition, due to the increase in the overall heat transfer coefficient, the lower heat transfer surface area is required for the fixed value of effectiveness. Finally, variations of objective functions versus particle volumetric concentration for five typical optimum points are estimated. It is concluded that an optimal value for the volumetric concentration can be obtained, in which the effectiveness is highest.

Experimental studies on pressure drop characteristics of cryogenic cross-counter flow coiled finned tube heat exchangers

Cross-counter flow coiled finned tube heat exchangers used in medium capacity helium liquefiers/refrigerators were developed in our lab. These heat exchangers were developed using integrated low finned tubes. Experimental studies have been performed to know the pressure drop characteristics of tube side and shell side flow of these heat exchangers. All experiments were performed at room temperature in the Reynolds number range of 3000–30,000 for tube side and 25–155 for shell side. The results of present experiments indicate that available correlations for tube side can not be used for prediction of tube side pressure drop data due to complex surface formation at inner side of tube during formation of fins over the outer surface. Results also indicate that surface roughness effect becomes more pronounced as the value of di/ D m increases. New correlations based on present experimental data are proposed for predicting the friction factors for tube side and shell side.

Enhancement of shell side forced convective heat transfer in the shell tube‐type heat exchanger using thin plate‐type supports

AbstractThe shell side heat transfer and pressure drop in counterflowing water were experimentally investigated on the basis of the overall heat transfer coefficient. The investigation was intended to identify ways to get higher performance for the cooler in a BWR nuclear power plant. The following three conclusions were reached in the study. (1) Predicted performance of the heat exchanger, using the overall heat transfer coefficient based on the outside area of the tube Ko, indicated an enhancement by 92% compared with the measured performance of the conventional segmental baffle‐type heat exchanger. (2) The tube side pressure drop ΔPt=20 kPa and the shell side pressure drop ΔPs=70 kPa were obtained, and were within the allowable value ΔPa=80 kPa. The shell side pressure drop of the low‐pressure drop spacer could be decreased by 20% as compared with that of the standard spacer. (3) The enhancement constant of the shell side heat transfer using the low‐pressure drop spacer was about 1.2 times as large as that of the standard spacer, regardless of the pumping power. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(5): 455–471, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10097

Heat Exchanger Design Targets for Minimum Area and Cost

A methodology is proposed to determine the feasible region for shell and tube heat exchanger designs on a pressure drop diagram. By accounting for operating as well as geometrical constraints, the feasible region is de®ned so as to eliminate trial-and-error during the design activity. Every point on this plot of shellside versus tubeside pressure drop corresponds to a unique design in terms of tube length, shell diameter and baffle spacing. Furthermore, curves may be plotted for designs corresponding to a specified heat exchange area or a given total annual cost. Such curves permit screening of various design options prior to detailed rating of the exchangers, and allow heat exchanger design targets to be established for minimum area or cost. The area target ensures an exchanger of the smallest size with minimum capital cost, whereas the cost target yields the optimum pressure drops accounting for the tradeoff between power consumption and heat exchanger area. The methodology is equation-based and can be conveniently implemented on a computer.

Extension of Rapid Sizing Algorithm for Shell-and-Tube Heat Exchangers with Tube-Side Pressure Drop Constraint and Multipasses (Part B)

There are occasions in which process engineers need approximate estimates of the exchanger size rather than full detailed designs. These situations are often accompanied by a need for speed. This paper provides a simple procedure for exchanger sizing which is rapid and with reasonable accuracy. The methodology involved is described in detail here and it is shown that the procedure can be applied to pure counterflow and also for multipass exchangers.

Modelling of plate finned tube evaporators and condensers working with R134A

A model to predict the behaviour of finned tube evaporators and condensers working with R134a has been developed. For modelling of the refrigerant phase change, evaporation or condensation, the heat transfer and the pressure drop for the two-phase flow have to be calculated. Therefore, a number of correlations, the most recommended ones in the reviewed literature, have been analysed and compared. The results of this comparison are presented for the evaporation and condensation heat transfer coefficients and for the evaporator frictional pressure drop. Once the correlations have been implemented in the model and compared with the experimental results, the ones that work best for the studied heat exchangers have been ultimately selected. The experimental study to validate the model has been carried out in a small airconditioning unit with cross-flow air-refrigerant type heat exchangers. The results are compared with model predictions for thermal capacity, refrigerant superheat or subcooling, and tube-side pressure drop.

Performance Analysis of a Plastic Shell-and-Tube Heat Exchanger

This paper presents an experimental investigation of the performance of an all-plastic heat exchanger. Plastic conical turbulators were inserted in the exchanger tubes to enhance the overall heat transfer process 1.5 to 3.5 folds. The results of performance tests indicated a limiting value for the overall heat transfer coefficient corresponding to the thickness and the conductive thermal resistance of the plastic tubes. In addition, the results did not show significant increase in the total tube-side pressure drop due to the use of turbulators. The heat transfer enhancement was evaluated on a thermoeconomic basis using a dimensionless exergy destruction function. Physical and chemical characteristic tests conducted on the plastic material used, prevealed its excellent solubility resistance and relatively high softening temperature, which makes it attractive in some heat recovery applications.