Twisted Tapes Research Articles

Energy and exergy analysis of a newly designed photovoltaic thermal system featuring ribs, petal array, and coiled twisted tapes: Experimental analysis

Photovoltaic systems suffer from electrical efficiency loss due to increases in surface temperature. To tackle this problem, Photovoltaic Thermal, consisting of photovoltaic and tube configurations attached to its back, is suggested. This study attempts to develop a new collector design in photovoltaic thermal systems. The new design features ribs and petal arrays on its inner and outer surfaces and a coiled twisted tape positioned inside it. The study also uses silicon carbide enhanced nanofluid (0.3 % and 6 % volume concentration) and phased changing material (1 % volume concentration) to boost the thermal efficiency further. Using an indoor solar simulator, the study investigates the effects of mass flow rate in the range of (0.1–0.85) kg/s, solar irradiances of (400–1000) W/m2, and coolant types of (water, 0.3 % and 0.6 % SiC enhanced nanofluid, water and nanophase changing materials, and 0.3 % and 0.6 % SiC enhanced nanofluid and nanophase changing materials). Besides revealing the relationship between all the parameters studied, the results report a maximum electrical energy efficiency of 11.2 %, thermal energy efficiency of 86.2 %, and total exergy efficiency of 15.3 %. The system reached optimal power production of 25.99 W using a photovoltaic module with a maximum power rate of 30 W.

Nanofluid effect on dual-flow parabolic trough collector performance accompanies with passive technique using experimental data

Purpose Using passive techniques like twisted tapes and corrugated surface is an efficient method of heat transfer improvement, since the referred manners break the boundary layer and improve the heat exchange. This paper aims to present an improved dual-flow parabolic trough collector (PTC). For this purpose, the effect of an absorber roof, a type of turbulator and a grooved absorber tube in the presence of nanofluid is investigated separately and simultaneously. Design/methodology/approach The FLUENT was used for solution of governing equation using control volume scheme. The control volume scheme has been used for solving the governing equations using the finite volume method. The standard k–e turbulence model has been chosen. Findings Fluid flow and heat transfer features, as friction factor, performance evaluation criteria (PEC) and Nusselt number have been calculated and analyzed. It is showed that absorber roof intensifies the heat transfer ratio in PTCs. Also, the combination of inserting the turbulator, outer corrugated and inner grooved absorber tube surface can enhance the PEC of PTCs considerably. Originality/value Results of the current study show that the PTC with two heat transfer fluids, outer and inner surface corrugated absorber tube, inserting the twisted tape and absorber roof have the maximum Nusselt number ratio equal to 5, and PEC higher than 2.5 between all proposed arrangements for investigated Reynolds numbers (from 10,000 to 20,000) and nanoparticles [Boehmite alumina (“λ-AlOOH)”] volume fractions (from 0.005 to 0.03). Maximum Nusselt number and PEC correspond to nanoparticle volume fraction and Reynolds number equal to 0.03 and 20,000, respectively. Besides, it was found that the performance evaluation criteria index values continuously grow by an intensification of nanoparticle volume concentrations.

Twisted tapes in solar chimney-earth air heat exchangers for equipment downsizing and passive cooling

Harnessing solar and geothermal energy in hot and arid climates is an effective strategy to reduce building energy consumption. This research investigates integrating Twisted Tapes (TT) into Earth Air Heat Exchanger (EAHE) pipes within a Solar Chimney (SC)-EAHE system, aiming to reduce EAHE pipe length while meeting ventilation requirements and decreasing cooling demand. Two key innovations are introduced: first, this study pioneers the integration of TT into a SC-EAHE system; second, it comprehensively explores TT geometry optimization, analyzing the effects of width ratio and rotation rate across 77 configurations. Numerical simulations are conducted in ANSYS Fluent using the k-ε RNG turbulence model to investigate thermal performance and airflow characteristics. Findings reveal that TT integration results in a 153 % increase in Nusselt number. Additionally, it is shown that a 1 m SC diameter achieves ventilation of 4.8 Air Changes per Hour (ACH) using TT with a width ratio and rotation rate of 0.5, while reducing EAHE pipe length by 2.6 %. Increasing the SC diameter to 1.25 m, with a TT width ratio of 0.6 and rotation rate of 1.25, leads to a 13 % (35 m) reduction in EAHE pipe length while meeting a minimum outlet temperature of 290.15 K and ACH requirements. However, the benefit diminishes beyond a 1.25 m SC diameter. This study contributes to understanding of integrating TT into SC-EAHE systems, addressing the critical need for sustainable energy solutions and offering a novel and energy-efficient approach for passive cooling in extreme climates.

Investigating the Effect of Heat Transfer Influenced by the Application of Wavy Corrugated Twisted Tape Inserts in Double Pipe Heat Exchangers

This study investigates the heat transfer and friction factor characteristics in a heat exchanger utilizing copper wavy (corrugated) twisted tape inserts. By inducing turbulent flow within the inner tube of the heat exchanger, these inserts generated increased turbulence, thereby enhancing heat transfer and causing a rise in pressure drop. The copper twisted tapes, with various twist ratios (TR=10.7, 8.5, 7.1), measured 1 meter in length and 14 mm in width. The heat exchanger's outer tube was made of mild steel, with an outer diameter of 0.0198 m and an inner diameter of 0.0142 m, while the inner tube was constructed of copper, with an outer diameter of 0.038 m and an inner diameter of 0.032 m. The overall length of the pipe-in-pipe heat exchanger was 1.4 m. Bulk mean temperatures were recorded at different positions for various water flow rates, and new correlations for the Nusselt number and friction factor were derived from the results for the twisted tape inserts. The Reynolds number ranged from 5000 to 17000. Comparative analyses revealed that the wavy twisted tape with a twist ratio of 7.1 provided the highest heat transfer rate, showing a 172% increase in the Nusselt number and a 32.11% increase in the friction factor relative to a smooth tube.

Performance Analysis of Corrugated Twisted Tape Inserts for Heat Transfer Augmentation

This study explores the impact of wavy corrugated twisted tape inserts on enhancing heat transfer and reducing pressure drop in a double pipe heat exchanger. Cu inserts with twist ratios of 3.2, 4.2, and 5.2 were used to create turbulence in the inner tube. Varying water flow rates and measuring bulk mean temperatures at different points revealed significant improvements in heat transfer over smooth tubes. The insert with a 3.2 twist ratio achieved the highest Nusselt number increase (185%) and a 36.33% rise in the friction factor. These results highlight the effectiveness of wavy corrugated twisted tape inserts for optimizing heat transfer, with a 3.2 twist ratio identified as the most effective. Across Reynolds numbers from 4000 to 18000, Nusselt number increases were 77.75% for a 5.2 twist ratio, 167% for a 4.2 twist ratio, and 185% for a 3.2 twist ratio. Friction factors rose by approximately 10.42% for a 5.2 twist ratio, 32.54% for a 4.2 twist ratio, and 36.33% for a 3.2 twist ratio, demonstrating the relationship between twist ratio, heat transfer enhancement.

Augmentation of heat transfer in a DPHE with bowl cut twisted tape inserts and TiO2/CuO hybrid nanofluids

Double pipe heat exchangers, or DPHEs, are employed in the power, oil, and process sectors. They cannot handle demanding applications. They have restrictions if they have to be utilized for heavy-duty applications. To get beyond these restrictions and use them for heavy-duty applications, heat transmission must be improved. In this work, a DPHE fitted with bowl-cut twisted tapes at different scale ratios (25, 50, and 75%) width (D) of bowl-cut from the center and circulated with TiO2/CuO hybrid nanofluids (NFs) is studied to assess its friction factor, thermal performance factor and Nusselt number. The working fluid was TiO2/CuO hybrid nanofluids (NFs) at varying concentrations (0.01, 0.03, and 0.05%) with Reynolds numbers from 2000 to 12,000. The bowl-cut twisted tape’s twisted ratio (H/D = 3) was kept constant. The hybrid NFs’ Nusselt number improvement was 66.09% more than that of the conventional tube. For varying scale ratios, the improvement in heat transfer was found to be 83.35, 115.31, and 172% with the bowl-cut twisted tapes and hybrid NFs. It was discovered that the friction factor penalty was 8.28, 0.83, and 1.075 times greater than that of the carrier fluid. Additionally, it was noticed that the thermal performance factor (TPF) was 1.65 times higher than the original fluid.

Predicting Heat Transfer Enhancement with Twisted Tape Inserts Using Fuzzy Logic Techniques in Heat Exchangers

Fuzzy logic, introduced by Lotfi Zadeh in 1965, is a powerful method for modelling complex experiments. This study utilizes fuzzy logic to simulate and predict heat transfer in a double-pipe heat exchanger equipped with wavy inserts. The inserts, in the form of twisted tapes, have varying twist ratios (TR=9, 7, 6). The study investigates a range of Reynolds numbers (Re) from 6000 to 18000, with friction factors ranging from 0.03620 to 0.08231, and Nusselt numbers (Nu) between 66.13 and 253.28. The results for different twist ratios are compared to the ideal case. The experimental results indicate that the highest heat transfer occurs with a twist ratio of 6, leading to a significant increase of 162% in the Nusselt number and a 36.21% rise in the friction factor compared to the ideal scenario. In the fuzzy logic framework, the input variables are the twist ratio (Tr), temperature, and Reynolds number (Re), while the output variables are the friction factor (f) and Nusselt number (Nu). The study demonstrates that the Mamdani fuzzy inference system is an exceptionally effective tool for predicting experimental outcomes, given its low error rate. Upon analysing the data, it is observed that the graphs plotting the Nusselt number versus Reynolds number and friction factor versus Reynolds number, derived from both experimental data and the fuzzy logic model, exhibit nearly identical trends with a margin of error of just 3%. This high level of accuracy underscores the reliability of the fuzzy logic model in replicating the experimental results.

Investigations of the effect of circular perforations and V-cut on SLTT in DPHE: An experimental analysis using IoT approach

The objective of this research is to explore the characteristics of the mean Nusselt number, friction factor, and enhancement efficiency in a double pipe heat exchanger. The emphasis lies in using short twisted tapes featuring round holes and a V-shaped cut. To conduct the experiment, an IoT-based DPHE setup was employed. In the experiment, various twisted tape configurations were examined to investigate their impact on heat transfer and pressure loss. These configurations included a full-length twisted tape and three short-length tapes with different perforation diameters. The full-length tape, with a twist ratio of x/ b = 4, spanned throughout length of the tube. In contrast, the plain short-length tape and modified short-length tapes, with the same twist ratio, were inserted in the section’s entrance. The shorter inserts, with a length ratio (LR = ls/lf) of 0.50, were compared to the full-length tape. The experimental findings demonstrated that the short-length tapes with LR = 0.50 consistently exhibited lower thermohydraulic performance compared to full-length inserts. Specifically, within the Re range of 4000–24,000, Nusselt numbers and friction factors for the short inserts were approximately 11%, 9.1%, and 6.1% lower, and 20.6%, 16.1%, and 11.2% lower, respectively, compared to the full-length inserts.

Experimental and Numerical Study of Heat Transfer and Pressure Drop Non-Newtonian Nanofluid in Corrugated Tube with Twisted Tapes

Experimental and Numerical Study of Heat Transfer and Pressure Drop Non-Newtonian Nanofluid in Corrugated Tube with Twisted Tapes

The Development of a Next-Generation Latticed Resistojet Thruster for CubeSats

CubeSat and small satellite resistojet heat exchanger designs are based on conventional concepts that have been used since the 1960s, being primarily limited to helical or twisted tape heat exchangers. The design flexibility enabled by new additive manufacturing technologies is yet to be properly harnessed. This study introduces a novel resistojet concept that incorporates a highly miniaturized lattice structure as the heat exchanger. A conjugate heat transfer analysis determined that the lattice with a diamond unit cell had superior thermal performance compared to the same lattice with a gyroid unit cell and increased the heat transfer rate by up to 11% compared to a helical heat exchanger of the same volume. Performance testing of the prototype thruster with integral diamond lattice indicated that specific impulses of up to 94 s were possible with a 30-Watt heater using nitrous oxide as the propellant. The prototype thruster weighed only 22 g and demonstrated a 67% reduction in the power required to achieve the same specific impulse as previous nitrous oxide resistojets designed for the small satellite platform. The development of highly miniaturized latticed resistojets is shown to be feasible and highly attractive for CubeSats, where mass and power are of the utmost importance.

Enhancing heat exchanger performance with perforated/non‐perforated flow modulators generating continuous/discontinuous swirl flow: A comprehensive review

AbstractHeat exchangers are crucial in transferring heat and finding applications across various industries. Numerous strategies have been devised to improve and optimize the heat transfer process within these systems. Among these, passive methods have garnered significant attention for their ability to operate without external power consumption. This article examines the recent experimental and computational studies conducted by researchers since 2018 on passive enhancement techniques, especially twisted tape, wire coil, swirl flow generator, and others, to boost the thermal efficiency of heat exchangers and aid designers in adopting passive augmentation methods for compact heat exchangers. Recently, researchers' new class of flow maldistribution devices, referred to as swirl flow devices, has gained attention; which enhances convective heat transfer by introducing swirl into the main flow and disrupting the boundary layer at the tube surface through alterations in surface geometry. Twisted tape inserts are devices that demonstrate better performance in laminar flow compared to turbulent flow. Conversely, other passive techniques like ribs, conical nozzles, and conical rings are generally more effective in turbulent flow than laminar flow. A recent research trend is the utilization of nanofluids in combination with other passive heat transfer enhancement techniques like turbulators, ribs, and twisted tape inserts in heat exchangers, which can reduce exergy losses and improve overall convective heat transfer coefficient and effectiveness of heat exchanger.

Effect of twisted tapes and surface extensions in enhancing the condensation heat transfer of high-temperature saturated steam in a circumferential rectangular channel

This article numerically investigates the impact of twisted tapes and extended surfaces (fins) on enhancing high-temperature steam flow in a circumferential rectangular channel, akin to the external jacket cavity of a tyre cure press. The passive enhancement techniques for improving the mold warm-up time of the tyre curing process have received limited attention in previous studies, which have primarily focused on enhancing heat transfer in configurations and working conditions typical of heat exchanger applications. The objective of this article is to enhance the condensation heat and mass transfer rate by geometrically modifying the internal flow path of the circumferential rectangular channel, resembling an external jacket cavity of a tyre cure press, using twisted tapes and extended surfaces. Four configurations are simulated: i) conventional circumferential rectangular channel, ii) channel with twisted tapes, iii) channel with surface extension, and iv) channel with both twisted tapes and surface extension. The heat transfer performance of all the modified channel configurations derived from the simulation results is assessed in comparison to the conventional channel. The channel, featuring a design that includes five twisted tapes with a twist ratio of 8 and 54 extended surfaces, records a substantial 36.85% rise in heat flux along with a notable 24% increment in the condensation mass flux. The simulation results are validated using an in-house experimental study. The tyre cure press in the experimental setup is modified to align with the design proposed by the simulation results, and a warm-up study is conducted. The warm-up time for the modified mold to attain the desired temperature is reduced by 33%, with no accompanying increase in steam consumption, compared to the warm-up time for the conventional mold. This significant reduction in mold warm-up time holds immense potential in enhancing the productivity rate, an ongoing requirement of the automobile industry.

Optimization of Twist Winglets–Cross-Section Twist Tape in Heat Exchangers Using Machine Learning and Non-Dominated Sorting Genetic Algorithm II Technique

Optimization of Twist Winglets–Cross-Section Twist Tape in Heat Exchangers Using Machine Learning and Non-Dominated Sorting Genetic Algorithm II Technique

Numerical investigation on effects of plain, perforated, and dimpled twisted tape inserts in a tube to flow and heat transfer characteristics

This research delves into improving heat transfer within tube by incorporating twisted tape inserts numerically comprising seven cases: basic twisted tape, perforated twisted tape with lengths of 25, 50, and 100mm, dimpled twisted tape with lengths of 25, 50, and 100mm. Analyses have been conducted at five different Reynolds numbers (10,000, 12,000, 15,000, 18,000, 20,000) using water as the working fluid. Physical dimensions of the geometry include tube length of 1000mm, inner diameter of 17mm, and outer diameter of 21mm. The twisted tape is also 1000mm long, with width of 17mm and thickness of 1mm. Results are compared to smooth tube in terms of Nusselt number and friction factor. Best improvement was obtained for 25mm dimpled twisted tape with 42%, while improvement for perforated tape was 28.7% and for plain tape 24%. Higher friction factors were obtained at 25mm dimpled tape making these configurations useful for industry despite pressure drop.

Investigating the effect of using aluminum oxide nanofluid and twisted tapes with different twisted pitches on the heat transfer efficiency and using perceptron artificial neural networks in data prediction

This study investigates the effect of aluminum oxide nanofluid with 1% and 2% volume fractions (VFs) in four different tubes with identical bending and the uniform, low-high-low, low-high, and high-low-high longitudinal states with twist ratios of 0, 2 and 4. These tubes are affected by a constant thermal flux of 10000 W/m2 and Reynolds numbers of 2000-10000. For the numerical solution of these equations, the finite difference method on the basis of the control volume and the SIMPLEC algorithm and the K-ε-RNG method were applied for the turbulent flow modeling. The determined Nusselt number from the numerical methods were evaluated applying the perceptron neural network. The most optimal increase in the Nusselt number was in the twisted tube with twist ratio of 4 in the Reynolds number of 10,000 and VF of 1% and 2% nanofluid with increasing trend of length from low to high. The most optimal increase in Nusselt number compared to base fluid was about 25%. The sum of squared error and the relative error data obtained from the hyperbolic tangent function for the training and test data were 0.080-1.331 and 0.113-0.675, and from the sigmoid function for the training and test data were 0.093-0.392 and 0.097-0.147.

Effect on performance of a CTHE by using twisted tapes and Al2O3 nanofluids: an experimental study and correlation development

Effect on performance of a CTHE by using twisted tapes and Al2O3 nanofluids: an experimental study and correlation development

Numerical Simulation of Heat Transfer Enhancement of a Heat Exchanger Tube Fitted with Single and Double-Cut Twisted Tapes

Numerical Simulation of Heat Transfer Enhancement of a Heat Exchanger Tube Fitted with Single and Double-Cut Twisted Tapes

A channel with hybrid twisted tapes for immersion cooling battery thermal management system

The promotion of transport electrification represents a pivotal strategy in addressing the energy crisis, wherein the adoption of the electric vehicles (EVs) plays a crucial role towards the realization of this goal. Immersion cooling battery thermal management systems (ICBTMS) emerge as an innovative strategy to guarantee the safe operation of the EVs. This study proposes an immersion cooling battery thermal management system with twisted tapes channel (TT-ICBTMS), offering effective temperature regulation of the battery pack. Drawing upon the experimental and simulation results associated with the high-capacity square battery, this paper selects a channel for further experimentation and simulation to elucidate the mechanisms by which various cooling methods and twisted tape configurations impact cooling efficacy. Subsequently, predicated on the comprehensive evaluation results, the channel with the hybrid twisted tapes (H-TT) is proposed. The H-TT, comprising both reverse twisted tapes (R-TT) and hollow reverse twisted tapes (HR-TT), serves to mitigate battery temperature rise, diminish pressure drop, and reduce the maximum temperature difference. This paper examines the heat transfer performance of the channel with the H-TT, revealing that, at the flow rate of 0.5 L/min and the discharge rate of 3C (Idischarge = 654 A), the maximum temperature of battery reaches merely 36.47 °C, with the maximum temperature difference of battery module being confined to 1.81 °C. Finally, a methodology employing the porous structure as the replacement for the H-TT in simulations is introduced in this study, a tactic validated through juxtaposition of experimental and simulation results, and subsequently applies this method in battery pack simulations. The simulation results demonstrate that, within the immersion cooling battery thermal management system with hybrid twisted tapes channel (H-TT-ICBTMS), the maximum temperature is confined to a mere 36.29 °C, with the maximum temperature difference limited to 2.63 °C, under the conditions of the flow rate of 22.5 L/min and the discharge rate of 3C (Idischarge = 654 A). This study posits that the H-TT-ICBTMS heralds novel thermal management paradigms for EVs.

Energy, exergy analysis, and RSM modeling of different designed twisted tapes in placed PV/T systems

This study numerically investigated the cooling effect, energy, and exergy analyses of twisted tapes with different pitch ratios (3, 4, and 5), widths (5, 7.5, and 9.5 mm), and thicknesses (0.5, 1, and 1.5 mm) on PV/T systems between Reynolds numbers of 500 and 1900. The research revealed a positive correlation between surface temperature and both thickness and pitch, but width showed a negative correlation with surface temperature. The maximum measured PV/T surface temperature was 320.437 K, and the minimum was 307.929 K. The thermal efficiency declined as the thickness, pitch, and width increased. The maximum thermal efficiency reached 59.35%. The highest Performance Evaluation Criteria (PEC) value of 1.535 was obtained with a width of 9.5 mm, a pitch ratio of 3, a thickness of 0.5 mm, and a Reynolds number of 500. The exercise evaluations revealed the advantageous impact of including a twisted tape insert in a PV/T system. The maximum electrical efficiency of exergy was 13.77%, while the maximum thermal efficiency of exergy was 1.59%. The RSM (Response Surface Methodology) was used to analyze the 405 numerical data acquired. Based on the analyzed parameters, equations were produced that may be applied to future geometries.

Heat transfer and flow characteristics of a plate-fin heat sink equipped with copper foam and twisted tapes

The objective of this paper is to present new heat transfer enhancement approaches in plate-fin heat sinks (PFHS) using copper foam and twisted tapes. The motivation behind these concepts is to reduce pressure drop while enhancing heat transfer compared to PFHSs fully inserted with copper foam. The impact of twisted tape type, twist ratio, and Reynolds number (Re) on the heat and flow behaviors inside the PFHS equipped with copper foam (PFHSCF) is investigated. Copper foam has a porosity of 0.932 and a pore density of 40 pores per inch. Stationary and rotating twisted tapes with twist ratios between 2.7 and 4 are tested at Re between 3000 and 6000. The experimental results indicated that the pressure drop of the airflow inside a PFHS equipped with copper foam and a stationary twisted tape (PFHSCF_STT) as well as a PFHS equipped with copper foam and rotating twisted tapes (PFHSCF_RTT) decreased by an average of 34.8 % and 37.9 %, respectively, compared to a PFHSCF. When the twist ratio is decreased from 4 to 2.7, the thermal resistances of PFHSCF_STT and PFHSCF_RTT are reduced by 14.2 and 14.8 %, respectively. Based on assessment, the thermal-hydraulic performance of a PFHSCF_RTT with twist ratios of 2.7 and 3.3 is higher than that of a PFHSCF. To facilitate practical applications, correlations are proposed to predict the Nusselt number and friction factor. Additionally, considering the outcomes of the current study, conducting numerical investigations on the thermal performance of PFHS under different pore densities of copper foam and wider twist ratios of twisted tapes is recommended to determine optimal working conditions for future research.