Exchanger Tubes Research Articles

Empirical correlation to analyze performance of shell and tube heat exchanger using TiO2 Nanofluid-DI water in solar water heater

Recent studies have examined the thermal stability and reliability of TiO2 nanofluid-based heat exchangers under long-term operation in solar water heating systems. This includes assessing nanoparticle sedimentation, agglomeration, and degradation over time, as well as their impact on heat transfer performance and system reliability. In this study heat transfer and fluid flow characteristics of TiO2-DI-H2O (deionized water) nanofluid used in a shell and tube exchanger with different baffle angles under turbulent regimes were numerically explored. The proposed setup was run with nanoparticle concentration of 0 %–0.2 % and Reynolds numbers (Re) from 5000 to 15,000. Baffle angles of 10°, 20°, and 30° were chosen for turbulence analysis. It was observed that nanoparticle concentration strongly impacted the thermophysical properties. The results indicated that adding modest concentrations of TiO2 to DI-H2O significantly improves heat transfer and the Nu. At the Re of 5000 and 30° baffles, the Nu was 58; however, at the Re of 15,000, the Nu value was 88. The improvement in heat transfer of 62.85 %, 70.64 %, and 75.06 % was recorded for baffle angles of 10°, 20°, and 30° respectively, Furthermore, a notable increase in friction factor of 13.6 % at Re 15,000 was observed. However, the ideal baffle angle for maximum thermal performance is 30°. Finally, with shell temperature, it was established that 30° baffle orientation could provide the best h and Nu values and improve the overall performance of the heat exchanger. The obtained Nu was also compared with the existing correlations of literature in the turbulent regime with the aid of nanoparticles and presented for case applications.

Comparative experimental analysis of fluid flow in a concentric tube exchanger having semi hollow cylindrical macro inserts with nanofluid and base fluid

Comparative experimental analysis of fluid flow in a concentric tube exchanger having semi hollow cylindrical macro inserts with nanofluid and base fluid

Optimization study on acid condensation and anti-corrosion performance of 3-D finned tube heat exchangers

Low-temperature acid corrosion on flue gas heat exchanger surfaces seriously reduces the stability, safety, and economy of equipment operation. Efficient strategies are urgently required to improve the anti-corrosion performance of heat exchangers. In present paper, a three-dimensional heat and mass transfer model integrating the acid dew point, acid condensation rate, and solution concentration was developed to predict the corrosion characteristics on the surfaces of 3-D finned tube heat exchangers. Firstly, a comparative analysis of acid condensate characteristics for 3-D finned tubes with different configurations was performed. The results showed that the elliptical tube effectively improves the distribution uniformity of acid condensate rate and promotes anti-corrosion performance. Then, the effects of five operating parameters (gas temperature, gas velocity, water vapor concentration, acid vapor concentration and wall temperature) on overall corrosion characteristics were systematically examined in terms of acid dew point, condensation rate and solution concentration using single-factor and orthogonal analysis, and the effect order of each factor was determined. Furthermore, optimization analysis of anti-corrosion performance was conducted based on the orthogonal results, and the optimum working conditions (water vapor concentration below 11.8% and wall temperature of 347 K to 355 K) are recommended. This research can provide theoretical guidance for the anti-corrosion designation and optimization of 3-D finned tube exchangers.

Numerical investigation of entropy generation for flow boiling of R600A in the corrugated U-bend tube heat exchangers

The development of compact and efficient corrugated heat exchangers for refrigeration and air conditioning systems is reliant upon thermal-hydraulic performance, which is quantifiable in terms of entropy generation. Hence, this study presents the generation of entropy analysis for flow boiling evaporation with an environment-friendly refrigerant (R600a) in the novel design of corrugated (outward circular ribs corrugated, inward circular ribs corrugated, outward triangular ribs corrugated, and inward triangular ribs corrugated) U-bend tube exchangers. The performance of the corrugated tube heat exchangers has been reported in comparison with the smooth U-bend tube heat exchanger. The numerical calculations were executed using CFD code for various masses ranging from 100 to 400 kg/m2s at the saturation temperature and vapor quality of 20 °C and 0.2 respectively while 15 kW/m2 heat flux was applied on the external surface of the straight tubes. The results revealed that the entropy generation increases as the mass flux increases with the inward circular and triangular ribs corrugated tube having the highest generated entropy followed by the outward circular and triangular ribs corrugated and then the smooth tube with the least entropy generation. In reference to smooth tube for the mass flux of 100 kg/m2s, the entropy generation for inward circular and triangular ribs corrugated increased by 46.88% and 130.93% respectively while the outward circular and triangular ribs corrugated increased by 18.35% and 39.26% respectively. Lower dimensionless Bejan numbers were obtained in the corrugated tubes with respect to mass fluxes compared to the smooth tube. The fluid flow irreversibility contribution to the overall entropy generated was higher in the corrugated tubes due to the corrugation surface which causes swirl mixing. The results of the numerical calculations were confirmed and corresponded with those established in the literature.

Empirical Investigation of Thermal Features of Phase Change Material as Thermal Storage System

This paper presents an empirical investigation of the melting processes of phase change material (PCM) in a tube and shell heating exchanger utilizing solar thermal energy. The experiments were conducted outdoors in Al-Mussaib city, Babylon, Iraq (Lat 32.5° North, long 44.3° East), utilizing a north-south (N-S) collector oriented at a tilt angle of 32.5° from the horizontal. This work utilized pure Iraqi black paraffin with 12 kg as PCM. The main empirical rig involves a vacuum tube solar collector (VTSC) utilizing a tube and shell heating exchanger to melt PCM in the shell regime. Different rates of water flow inside the internal heating exchanger's tube, namely (3.5, 5, and 8.5 L/m), were utilized for each season from August 2022 to January 2023. The empirical findings concluded that the internal tube inlet and surrounding temps significantly influence the melting process compared to the rates of water flow. It was found that the melting process of PCM needs about (3 to 4) hours in the summer season. Still, winter needs a longer time, about 14 to 16 hours. Increasing surrounding temp and solar radiation reduces the melting time of phase-change material. The findings of the present work were compared with the earlier investigations and agree with increasing the present work by 23.5 %. The findings from the present study are of practical importance for industries requiring storage materials to improve thermal storage system performance.

Gum elastic bougie as a tube exchanger for the nasotracheal tube.

Gum elastic bougie as a tube exchanger for the nasotracheal tube.

Accelerating melting time in a triplex tube heat exchanger thermal energy storage unit with micro-channels

This article studies optimal conditions to maximize heat transfer efficiency within a triplex tube heat exchanger (TTHX) filled with phase-change material. In this context, micro-channels (MCs) incorporated into TTHX for the first time for acceleration melting time. A two-dimensional numerical model has been developed, and pure conduction and natural convection are both simulated. The Reynolds numbers range from 1 to 100. The types of temporal velocity profiles into micro-channels were uniform, step, elliptic, sinusoidal, and power. The effect of gravity states, namely no gravity, with gravity, and (MCHE), has been studied with different numbers of microchannels (4, 6, 8, 10, 12, and 14). The results showed that there was no variation in melting duration observed when increasing the Re number from 50 to 100. Thus, the maximum reduction in melting period occurred at Re = 50. Moreover, sinusoidal velocity profiles were more effective and could help the process finish sooner. In addition, micro channel tube exchanger (MCTE) fitted or equipped with 10 micro-channels has an optimum condition considering pressure drop and complete melting time. Using the sinusoidal profile reduced the total fusion time by 325 s compared to uniform flow (8.47 % reduction). This indicates that the sinusoidal profile is an effective way to reduce the melting period.

Integrated Assessment of Discrepancy Between Tracheal Tube and Tube Exchanger as Advancement: A Manikin Simulation Study.

Advancing a tracheal tube over a tracheal tube exchanger into the trachea frequently causes difficulties because of the tube impingement on laryngeal structures. In the present study, we measured the resistance of tube advancement both objectively and subjectively with a variety of combinations of tube exchanger sizes and tracheal tubes using a manikin simulator. Lubricated 7.5 mm ID standard and Parker Flex-Tip (PFT) tracheal tubes were railroaded over the tube exchangers (OD 1-6 mm) into the trachea through the oral route in a manikin. Consequently, 12 combinations of tracheal tube-exchanger tube assemblies were evaluated. Tube advancing resistance at the laryngeal inlet was subjectively evaluated. The objective tube advancing resistance (force) at the laryngeal inlet was evaluated using a digital force gauge. The execution of each tracheal tube-exchanger trial was conducted 10 times. With a 1-mm tube exchanger, all intubation attempts with both standard and PFT tubes failed. Esophageal intubation or severe impingement at the right arytenoid accompanied with a bent tracheal tube was observed. With a 2-mm tube exchanger, during intubation with a standard tracheal tube, rotation of the tube was sometimes required; however, all other intubations were done without problems. When PFT tubes were used, all intubation attempts were performed without problems. The rest of the trials were successfully performed regardless of the combinations of tube exchangers and tracheal tubes; however, one attempt of intubation with a combination of a 5 mm tube exchanger and a standard tracheal tube required withdrawal and rotation of the tube because of impingement at the epiglottis. In cases where there was no gap resistance, which means tube advancing resistance generated by a gap between an introducer and a tracheal tube, the pressing force was approximately less than 10 N. However, in the cases requiring some interventions to overcome the gap, the pressing force reached around 15 N. When intubation failed, for example when the tube bent, or esophageal intubation, the pressing force reached around 30 N. Impingement due to the gap between the tube exchanger and the tracheal tube is thought to occur in the PFT tube less frequently. Once an impingement occurs, we can feel approximately twice the amount of resistance as usual, which may be a chance to consider taking some interventions. When the impingement is not released, regardless of interventions, excessive force may result in esophageal intubation or tracheal injury.

“MRI Cooling System Analysis & Optimization: CFD, Temperature Control & Efficiency Enhancement”

This paper presents a compressive analysis and optimization of a twisted heat tube exchanger for MRI cooling system. The objective of this study is to enhance the efficiency and temperature control of the system adhering to ASHRAE standards by altering the coolant inlet temperature from 18° C to 27°C & the hot inlet temperature from 75°C to 100°C. The research encompasses design modifications, thermal analysis of tubes with varying lengths (400mm,800mm,1200mm), CFD Analysis simulation to understand fluid behavior. By employing these analyses & optimizations, we aim to improve the overall performance & efficiency of the MRI cooling system. This work not only contributes to the field of heat exchangers & MRI Cooling but also provides valuable insights for HVAC world by replacement of refrigerant or conventional MRI cooling system.

Thermal performance analysis of coils versus longitudinal C-shaped tubes: validity of the turbulent correlations

Compared to helically coiled tube exchangers (HCTs), longitudinally curved tube exchangers (LCTs) have received little attention from scientists over the past decade, leading to a lack of correlations estimating the Nusselt number and friction factor. In view of recent studies promoting the use of LCTs (waved, C-shaped or sinusoidal) in linear solar concentrating systems, this study examines whether or not correlations of and developed explicitly for HCTs could be applied to LCTs. A (SST) turbulent model has been run on HCTs and validated by experimental correlations from the literature. With an amplitude ratio equal to unity (waviness amplitude to the curvature radius ratio) and the same curvature ratio (tube radius to the curvature radius ratio), LCTs and HCTs are geometrically similar. For these similar configurations, the numerical results of over the Reynolds number range overlap almost perfectly, which is not for. Over the LTC amplitude ratio range, no significant change in the mean was reported, with a max relative error of 3.98%, whereas was highly dependent on it. One key finding: with a similar curvature ratio, correlations of the mean developed previously for HCTs could be used for LCTs, which is not valid for the mean.

A Tracheal Tube Exchanger Container As a Bronchial Foreign Body

A Tracheal Tube Exchanger Container As a Bronchial Foreign Body

Investigation of parabolic trough collector receiver with U-pipe exchanger using a numerical approach: Towards temperature non-uniformity optimization

In this work, a numerical study of the heat flux and temperature distribution for a parabolic trough collector absorber with an internal U-pipe tube exchanger is carried out using SolTrace and ANSYS Fluent software. The effect of solar flux and temperature non-uniformity on the system performance related to the focal distance is investigated. It was noticed that the highest circumferential temperature gap of about 105 °C occurs at the medium of the absorber (0.9 m). Moreover, for the focal distances of 0.18 m, 0.19 m, and 0.2 m, the outlet water temperatures are increased to 328.8, 329.01 and 328.89 K, respectively. For these distances, the highest thermal efficiencies of about 69, 70 and 71%, respectively, are reported. Furthermore, the promising proposed approach to investigate the receiver performance combines simulation results and correlations between variables. Indeed, a strong negative correlation of −0.65 between thermal efficiency and focal distance is noticed. Thus, thermal efficiency correlates positively with maximum temperature gap, inlet–outlet temperature gap, flow rate, and outlet temperature in decreasing order with correlation coefficients of 0.64, 0.59, 0.38, and 0.32, respectively. Additionally, the simulation study emphasizes the importance of relating optimum temperature uniformity and thermal efficiency for optimizing the system performance.

Steady State Heat Conduction in Exchanger Tubes by Using the Meshfree Boundary Integral Equation Method: Conduction Shape Factor and Degenerate Scale

AbstractRegarding the steady-state heat conduction problem in exchanger tubes, the meshfree boundary integral equation method is employed to determine the conduction shape factor in this paper. Different from the conventional boundary element method, the present method is free of mesh generation. After using the parametric function to represent the boundary contour and adopting the Gaussian quadrature, only collocating points on the boundary is required to obtain the linear algebraic equations. By introducing the local exact solution, the singular integral in the sense of the Cauchy principal value can be novelly determined. In addition, the boundary layer effect due to the nearly singular integral in the boundary integral equation can be dealt with. Two cases of different boundary conditions are considered. One is the isothermal condition on both the inner and outer surfaces. The other is the isothermal condition on the inner surface and the convection condition on the outer surface. Besides, numerical instability is found and the nonuniqueness solution due to the degenerate scale is examined by calculating the conduction shape factor and the temperature on the outer surface.

Evaluation of new dew point evaporative cooler heat and mass exchanger designs with different geometries

In this study four new geometries of heat and mass exchanger for dew point evaporative cooling are investigated and their performance is compared to that of the commonly used flat plate and corrugated plate exchangers. In the proposed exchangers, each dry channel is completely enclosed by its adjacent wet channels, and each wet channel is completely enclosed by its adjacent dry channels (related detailed information is presented graphically in this paper). In addition, a robust numerical model was developed and is examined under various operational and geometrical conditions. The analysis showed that the proposed dew point evaporative coolers improve the chilled air temperature, water consumption, cooling capacity, and energy efficiency. In particular, the circular concentric tube exchanger, under certain operating conditions (inlet air temperature, humidity ratio, and velocity of 40°C, 6 g/kg, and 3 m/s, respectively), could produce the lowest chilled air temperature of 9.6°C and the highest wet bulb and dew point effectiveness of 148% and 99%, respectively. Additionally, water consumption is reduced to 1.34 L/hr for an inlet air velocity of 1 m/s. A triangular tube exchanger achieved the highest cooling capacity and coefficient of performance, but consumed the largest amount of water. Our geometrical analysis demonstrates that the overall performance of dew point evaporative cooling systems can be improved by employing new geometries for heat and mass exchanger channels. Practical application: The dew point evaporative cooler is an environmentally friendly air conditioning system used in buildings. It is considered the strongest candidate to replace vapour-compression refrigeration systems because it consumes considerably less electricity while achieving high performance. Our research demonstrates that through revised geometry it is possible to further improve the performance of the system leading to improved energy and water efficiency.

Integrating a bench scale phosphate flash dryer to a solar heating source: integration challenges and monitoring system development

Aiming to reduce the energetic consumption and greenhouse emissions, integrating the energy-intensive dryer to a solar loop constitutes the optimum solution. This paper investigates the feasibility to integrate a bench scale flash dryer to a solar heating source. Initially, the choice of the best heating source was made and the design was realized. Then, the best configuration of the gas/liquid heat exchanger was selected to design the exchange surface. Finally, the solar flash dryer was mathematically modeled to simulate the dryer performances at various conditions. The parabolic through collectors were selected, with a nominal power of 29kWth, were coupled to a spiral finned tube exchanger with 24 kW capacity. The integration showed a significant dependency of the drying air temperature on the climatic conditions (DNI and incidence angle). The drying tests, realized at the most favorable and unfavorable conditions, showed an important decrease in the moisture fraction to be eliminated, increasing from 1.8% to 3.5% when the air temperature drops from 155 °C to 110 °C. It was hence necessary to develop a regulation system to ensure a continuous solid flow rate.

Safety and efficacy of the expressman extension system for complex coronary lesions during percutaneous coronary intervention.

Safety and efficacy of the expressman extension system for complex coronary lesions during percutaneous coronary intervention.

Analysis of the performance of the shell and tube heat exchanger: Influence of pipe layout and diameter

Heat exchangers are devices that are used in numerous areas of industry with the most important role in process technology. The growing need for maximum energy utilization contributed to the very rapid development of these devices. Of all types of heat exchangers, shell and tube exchangers are the most widely used in process technology. The paper analyzes the performance of a shell and tube heat exchanger of known geometric characteristics and rated power. Numerically and by simulation of fluid flow in the SolidWorks software package, a comparative performance analysis was performed depending on the different layout and for the values of the outer diameter of the pipe 33,7x2 mm and 60,3x2,7 mm for the same external dimensions of the heat exchanger. The obtained results show that the heat exchanger with a circular arrangement of pipes measuring 60,2x2,7 mm has the best performance, taking into account the achieved power of the exchanger.

Experimental Analysis to Enhance the Performance of Shell and Tube Exchanger With Ribs

Heat transfer has always been a significantly interesting topic with an eye towards developing highly efficient, inexpensive & light weight Heat Exchangers. This project is about enhancement of heat transfer through ribs. Ribs are an efficient & economic tool in heat transfer enhancement which can be used as an obstruction to fluid flow in order to promote turbulence, which would result in comparative increase in the amount of fluid particles coming in contact to the surface and also enhances the overall heat transfer coefficient by disturbing the fluid flow that would break thermal & viscous boundary layers. As a consequence of this, there will be a significant improvement in the Effectiveness of a Heat exchanger. In this study, a Shell & tube heat exchanger is designed, fabricated and also analyzed, where numerous tests are carried out with varying the number of Ribs utilized in the heat exchanger, in order to obtain a substantial increase in: i) Effectiveness ii) Overall Heat transfer coefficient.

Shell tube exchanger parametric investigation and performance simulation using ansys

Heat exchangers with shells and tubes are widely employed in the chemical, power generating, and petroleum refining industries. A three-dimensional simulation of a shell and tube heat exchanger with segmental baffles was performed in this paper. The research involves the use of commercial code such as ANSYS CFX, MATLAB, and Solid-Work, which incorporate modeling, meshing, and the use of finite element techniques to produce numerical results. The results have been achieved in transient situations. The purpose of this paper is to optimize and analyse temperature drops, pressure drops in side shells and tubes, stream-by-stream velocities, and parametric investigations such as the number of baffles, the distance between baffles, and the number of passes using the ANSYS program. The pressure drop that has been addressed shows that raising the baffle cut and reducing the baffle spacing have opposite impacts on the pressure drop. In many cases, the pressure drop on the shell and tube sidewalls was investigated as well. Pressure drop has been investigated in terms of the number of baffles, the gap between baffles, and the number of passes.

Improved heat recovery using twisted tube exchanger technology

The geometrical features of twisted tube exchangers enhance the thermo-hydraulic performance for the same fluid velocity compared to conventional heat exchangers. The benefit of its use becomes evident in design as the required heat duty is transferred with smaller surface area for even lower pressure drop compared with conventional exchangers. This work introduces the development of a thermohydraulic model for the twisted tube geometry that relates pressure drop and heat transfer coefficient. Aspect ratio and twist pitch are the parameters that most influence the thermo-hydraulic performance of these exchangers. An alternative sizing approach using the concept of full use of pressure drop step is presented. The application to high viscosity fluids is discussed. The results show a reduction in surface area compared to conventional shell and tube exchangers of up to 45% and a pressure drop reduction of 15%. • An alternative sizing methodology for twisted tube heat exchangers is introduced. • Design approach based on full use of available pressure drop. • Thermo-hydraulic model that relates heat transfer and pressure drop is developed. • Reduced size and pressure drop compared with conventional exchangers.