Thermal Enhancement Factor Research Articles

The effect of triangular shutter type flow deflector perforated baffle plate on the thermofluid performance of a heat exchanger

AbstractThe study aimed to investigate the heat transfer (HT) properties of a tubular heat exchanger (HX) by using innovative baffle plate arrangements. The newly designed baffle plate was circular with triangular openings and adjustable triangular flow deflectors. These deflectors were strategically placed at the inlet of the HX to create a swirling flow downstream. Three baffle plates were installed along the flow direction with different length‐to‐diameter ratios (pitch ratios) to assess their impact on HT, pressure drop, and thermal enhancement factor. The study compared these results with a smooth channel under varying Reynolds numbers (16,500–29,500). The findings revealed that both the pitch ratio (0.6–1.2) and the inclination angle of the deflectors (30⁰–50⁰) significantly affected the HX's performance. Notably, the baffle plate with a deflector inclination angle of 30° and a pitch ratio of 1 showed a remarkable average improvement of 36.5% compared to other angles and ratios.

Experimental Investigations on Single-Phase Heat Transfer Enhancement in an Air-To-Water Heat Exchanger with Rectangular Perforated Flow Deflector Baffle Plate

Experimental analysis was conducted to investigate the turbulent heat transfer behaviors within a tubular heat exchanger, incorporating a novel baffle plate design. The new design includes a perforated circular baffle plate with a rectangular flow deflector that can be adjusted to different inclination angles. The baffle plate is strategically positioned at the entrance of the heat exchanger, resulting in a swirling flow downstream. To assess the impact of the baffle plate design, three baffle plates were placed longitudinally along the flow, with varying pitch ratios (l/D). The effects of pitch ratio (ranging from 0.6 to 1.2), deflector inclination angle (ranging between 30⁰ to 50⁰), and Reynolds numbers (ranging between 16000 to 29000) were examined. The outcomes highlighted the substantial impact of pitch ratio and inclination angle on the thermal enhancement factor. In particular, compared to single segmental baffle plates working under similar operating conditions. The result indicates that an inclination angle of 30° and a pitch ratio of 1 exhibited an average 41.49% augmentation in thermal-fluidic performance compared with an exchanger with a segmental baffle plate.

Flow and thermal behavior of solar air heater with grooved roughness

A simple and eco-friendly solar air heater (SAH) converts renewable solar energy into useful thermal energy. The implementation of roughness on the absorber plate of a solar air heater improves its air heating capability. The hot air thus produced is used in different applications such as agricultural, dairy, food processing, and cement industries. Towards that, a 2D numerical study is carried out with rectangular groove as a roughness with the RNG k−Ɛ turbulent model. The study has been carried out to find a SAH with higher performance. Two thermodynamic models are adopted to identify and qualify the best channel. The performance of the best SAH channel has been identified by the highest thermal enhancement factor (TEF) and to increase the exergetic ratio (Ɛth). A detailed study of introducing rectangular groove on heat transfer, pressure drop, thermal enhancement factor (TEF) and exergetic ratio (Ɛth) is conducted, by varying the geometrical parameters of rectangular grooves in the range of Re from 7000 to 17000. Geometrical parameters such as relative length (α), relative pitch (β) and relative height (λ) are varied in the range of 0.0067–0.040, 0.0333 to 0.10, and 0.1 to 0.5, respectively, to optimize the performance of the SAH. Higher exergetic ratio is found around the same parametric values where we get the highest TEF value. The maximum TEF is found around 1.455 at α = 0.020, β = 0.0667, and λ = 0.30 at Re of 17000 and the corresponding exergetic ratio is found around 0.9949. The length of the groove is found to augment both heat transfer and pressure drop of the solar air heater due to increased disruption of thermal and hydrodynamic boundary layers. Rate of augmentation of heat transfer decreases in case of α≥ 0.0333 due to formation of an additional stagnant zone inside the groove. The flow and thermal analysis shows that although local heat transfer within the rectangular groove is less, the rectangular groove improves the channel's overall heat transfer. Convective heat transfer coefficient is found relatively higher where there is a change in shear stress gradient.

Thermal performance enhancement in a double tube heat exchanger using combination of bubble injection and helical coiled wire insert

In this experimental study, a novel approach combining a helical coiled wire (HCW) turbulator and bubble injection (BI) method has been employed to synergistically improve the heat transfer efficiency of double tube heat exchanger. The thermal-frictional characteristics were evaluated by investigating different parameters, including the bubble injection flow rate ranging from 2 to 5 l/min and HCW pitch ranging from 2.5 to 10 mm. For all cases, the thermal enhancement factor (TEF) is employed to determine the optimal configurations. The experimental findings indicate that the introduction of bubble injection, the implementation of the HCW turbulator, and the simultaneous utilization of both methods result in an enhancement of heat transfer by 66 %, 78 %, and 156 % respectively. However, it should be noted that the usage of these methods also leads to an increase in pressure drop. Also, the findings indicate that the integration of two methods yields favorable outcomes in terms of thermal performance when compared to their individual functions. In the optimal scenario, the TEF has the potential to reach a maximum value of 1.28. Furthermore, in order to obtain a more precise comprehension of the relationship between TEF and the parameters under investigation, an empirical equation have been derived and presented.

Experimental Analysis of a Solar Air Heater Featuring Multiple Spiral-Shaped Semi-Conical Ribs

Abstract To improve the thermal and hydraulic performance of artificially roughened solar air heaters (SAHs), the current study analyzes the thermal-hydraulic performance or thermal enhancement factor of artificially roughened solar air heaters. In present experimental research on a solar air heater's absorber plate, newly designed spiral-shaped semi-conical ribs have been explored. The spiral-shaped semi-conical ribs have been designed with the aim of reducing the pressure drop across the rib so that thermal performance may be improved with a little increase in pressure drop after integrating the ribs into the SAH mainstream flow. The higher value of thermal-hydraulic performance indicates an increased heat transfer rate with a minimum increase in pumping power. In order to achieve the highest possible thermal enhancement factor, this experimental study intends to analyze the effects of different geometrical parameters on the heat transmission and friction behavior of numerous spiral-shaped semi-conical ribs. Multiple experiments were conducted using different levels of roughness heights to optimize the rib profile parameters. The Reynolds number (Re) ranges from 3358.65 to 18,095.59, the relative roughness height (e/Dh) 0.09 to 0.227, and relative roughness pitch (P/e) 3.7 to 5.5. These multiple spiral-shaped semi-conical ribs give the maximum thermal enhancement factor of 2.85 at (e/Dh) 0.182 and P/e of 4.1 at Reynolds number 18,095.59. It has been found that current rib geometry can increase the thermal performance of solar air heaters with minimum increased pumping power with reference to rib explored by earlier researchers.

Heat transfer augmentation of solar air heater using discrete transverse sinewave corrugations

The influence of discretely placed sinewave corrugations on the effective thermal performance of the solar air heater system is presented using numerical methodology. The effect of forward and backward arrangement, normalised wavelength and amplitude on heat transfer enhancement is evaluated for different Reynolds number ranging between 6000 and 24,000. The non-dimensional wavelength and amplitude is varied as 0.0125–0.05 and 0.05–0.2 respectively while the non-dimensional pitch is taken as 1.875. The results show that the forward arrangement pattern of sinewave corrugation provides better thermo-hydraulic performance than the backward arrangement. For any given non-dimensional wavelength, lower non-dimensional amplitude exhibits greater thermal enhancement factor while for a fixed non-dimensional amplitude, the wavelength ratio of 0.025 provides greater thermal enhancement factor. The corrugation having amplitude ratio of 0.1 and wavelength ratio of 0.025 exhibits the highest thermal enhancement factor of 1.69 at Reynolds Number of 6000. It is also observed that, for Reynolds Number lesser than 9000, the configuration of amplitude ratio of 0.1 is found to exhibit higher thermal enhancement factor for any given non-dimensional wavelength. However, for Reynolds Number greater than 9000, the configuration of amplitude ratio of 0.05 is found to exhibit higher thermal enhancement factor for any given non-dimensional wavelength.

Thermal enhancement and entropy generation of an air-cooled 3D radiator with modified fin geometry and perforation: A numerical study

The increasing fuel prices have led researchers to work on the efficiency and development of heat-transferring devices. One such device is the hot water radiator, which is familiar in the domestic arena. The study aims to increase the efficiency and cooling performance of hot water 3D radiators by modifying the design of their fins and adding perforations for better fluid mixing. CFD simulations were carried out on the radiators with modified fin geometries (Wavy, Spike-rib, Cut-sections, Straight) and with two different intensities of perforation (19 and 38 perforations) for each case at varying inlet flowrates of the radiator. The numerical model in this study was validated with experimental work. The hydrothermal performance of each radiator was measured in terms of fin surface temperature, entropy generation, heat transfer rate, and thermal enhancement factor. The temperature distributions and fluid flow streamlines have also been shown. The results show that modifying the fin geometries augments the overall heat transfer rate by up to 131 % while perforating the fins boosts the rate to 134 %. Moreover, the radiation heat transfer is seen to have surpassed the convection heat transfer by 60–160 % for the modified radiator cases. Finally, the most efficient radiator is found based on the thermal enhancement factor, which is the spike-fin arrangement.

Surrogate-based optimization of the attack and inclination angles of a delta winglet pair vortex generator in turbulent channel flow

Vortex generators (VGs) have been extensively studied and utilized in multifunctional heat exchangers/reactors due to their remarkable ability to create coherent flow structures and streamwise vortices. These characteristics significantly enhance the mixing and heat transfer performance in laminar and turbulent flow regimes. With the advancement of computational power, VG shape optimization has become feasible, leading to the discovery of various optimized shapes in the literature for different Reynolds numbers. In this paper, the response surface polynomial method is employed as a surrogate model to optimize the angle of attack and inclination angle of a delta winglet VG at a Reynolds number of 4,600. The potential applications of these optimized designs are diverse, particularly in scenarios that require cooling or heating. Some examples include photovoltaic (PV) panel cooling, waste heat recovery in hybrid PV/solar water heating systems, energy-efficient HVAC systems, and thermal management in electric vehicles. To achieve this objective, Computational Fluid Dynamics (CFD) simulations are conducted to compute the thermal performance factor of each VG design at various values of attack and inclination angles. By enhancing mixing and heat transfer capabilities, this design can have a substantial impact on various renewable energy applications, contributing to a greener and more sustainable future. The highest thermal enhancement factor of 1.15 is found to be achieved for an inclination angle of −45° and an angle of attack of 35°. This means that optimized VG enhances heat transfer by 15% compared to empty channel flow, while maintaining the same pumping power.

Mini-channel cooling system for solar PV Panels with hybrid magnetic nanofluid and magnetic field

This study delves into the interplay between magnetic fields, heat transfer, and fluid behavior within a 3D mini-channel. Exploring the effects of a magnetic field on a hybrid nanofluid (Fe3O4–TiO2) under varying intensities (1000–2000 Gauss) and positions. Using numerical simulations (finite volume method), key parameters like Nusselt number (Nu), Friction factor (f), and Thermal Enhancement Factor (TEF) have been analyzed to uncover how magnetic fields and nanofluids interact in complex geometries. Results showed that the application of a magnetic field significantly enhanced heat transfer performance, with a maximum Nusselt number enhancement of 230%. Moreover, it was shown that greater magnetic field intensities were associated with elevated friction factors, whereas friction factors exhibited a declining trend as Reynolds numbers increased. The thermal enhancement factor initially increased with Reynolds numbers, but declined after reaching a peak. However, higher magnetic field strengths mitigated this decline, intensifying heat transfer enhancement effects reaching a maximum of 2.18 at 2000G magnetic field. These findings provide quantitative insights into the effectiveness of magnetic fields in enhancing heat transfer in Fe3O4–TiO2 hybrid nanofluids.

Effectiveness of a tubular heat exchanger and a novel perforated rectangular flow-deflector type baffle plate with opposing orientation

Purpose The purpose of this experimental research was to examine a novel axial heat exchanger featuring swirling air movement over heated tubes. This apparatus is designed with perforated circular baffle plates complemented by rectangular air deflectors operating at different inclination angles. The tubes were arranged in a consistent layout parallel to the longitudinal airflow. The deflector’s heightened air-side turbulence initiates the frenzied motion, escalating the surface heat transfer rate. Design/methodology/approach The tubes maintained a constant heat flux condition over the surface. In each baffle plate, eight deflectors with identical inclination angles were devised in a reverse position, forming a rotation of air inside a circular duct that held tubes (carrying hot water) which elevated air-side turbulence, thereby enhancing the rate of heat transference on the surface. The baffle plates were equally situated from each other at changing pitch ratios. The Reynolds quantity was preserved in the scope of 16,000–30,000. The performance of the heat exchanger considering pitch ratios and inclination angles was examined. Findings The research indicates that when examined under similar conditions, an exchanger with a deflector baffle plate shows a strong dependence on the pitch ratio and inclination angle with a mean rise of 0.19 times in thermal enhancement factor at an inclination angle of 30° and a pitch ratio of 1.2 contrasted with an exchanger with segmental baffle plates. Originality/value The result shows the dependence of pitch ratio, Reynolds number and inclination on the heat transfer and friction factor rate.

Innovative concept of vortex generator-equipped multi-drain heat recovery systems–Numerical study and energetic analysis

In light of the environmental concerns associated with the misuse of fossil fuels and the increasing consumption of energy, heat recovery systems have become an essential option for conserving energy. In this study, an innovative design that couples a highly efficient vortex generator-based heat exchanger with a new multi-drain water application for 48 accommodations is suggested. A numerical study is done by varying the flow rate and investigating the effect on the heat transfer, overall heat transfer, and thermal enhancement factor. Besides, the economic and environmental impacts of the system are studied to investigate its sustainability. Four types of input energy are studied: coal, diesel, gas, and electricity. Results show that the design provides a temperature increase of 3.5 to 7.5 °C of cold water, consequently, the daily environmental savings are up to 0.87 € (for gas), 1.74 € (for diesel), 4.63 € (for coal), 17.63 € (for electricity US) and 2.26 € (for electricity FR). Besides, the daily economical savings are up to 7.54 $, 8.63 $, 4.63 $, and 15.07 $ respectively with a payback period of around 0.61, 1.2, 1.42, and 2.89 years for gas, diesel, coal, and electricity respectively.

Heat transfer and pressure drop in a double pipe exchanger equipped with novel perforated magnetic turbulator (PMT): An experimental study

The utilization of a magnetic turbulator presents a novel method for enhancing heat transfer in heat exchangers. This research introduces the use of both simple and perforated magnetic turbulators for the first time, aiming to optimize the thermal enhancement factor. The perforated magnetic turbulator is a composite of a magnet and a perforated oscillator. By inducing an alternating magnetic field around the tube, the magnet and, thus, the oscillator are forced to oscillate and as a result act as a flow disruptor. The oscillator is designed with holes in four varying diameters 1, 2, 3, and 4 mm and five distinct pitches 4, 6, 12, 18, and 24 mm to examine the impact on pressure drop and heat transfer. Also, to ascertain the optimal case, the thermal performance factor has been used. Tests have been carried out in the hot fluid flow range from 0.23 to 1.38 l/min. According to the results, the highest amount of heat transfer has been observed in the presence of a simple magnetic turbulator. The heat transfer and friction factor ratio in the presence of best case were 1.67 to 5.7 and 1.04 to 1.34 times higher than those of the plain tube, respectively. Meanwhile, the maximum value of the thermal performance coefficient (5.35) was observed in the presence of a perforated turbulator with a hole diameter of 2 mm and a pitch of 6 mm.

Thermoeconomic and environmental impacts of vortex generator-equipped multi-drain heat recovery systems under various renewable sources

In response to escalating energy demands, intensifying climate change concerns, and growing environmental degradation, the incorporation of renewable energy sources has gained traction across diverse sectors and regions. Concomitantly, scientists and engineers have recognized the potential of heat recovery systems in mitigating energy consumption, fostering further investigations into their practical applications. This study introduces an innovative design, integrating vortex generators into a concentric tube heat exchanger for heat recovery from a multi-drain water system that serves 48 accommodations. The design's sustainability is assessed by evaluating its economic, and environmental implications when paired with various renewable energy sources. Specifically, the aim is to quantify both cost and environmental savings engendered by implementing this design in a multi-drain application for a building with 48 accommodations.A numerical investigation elucidates the effects of flow rate variations on heat transfer, overall heat transfer, and thermal enhancement factors. Four types of renewable energy input - solar, wind, biomass, and hydropower - along with one storage system (pumped storage) are analyzed. The study reveals that the design implementation results in an elevation of cold water temperature between 3.5 and 7.5 °C. Furthermore, daily environmental savings for solar, wind, biomass, hydropower, and pumped storage are estimated to be 0.783 €, 0.339 €, 0.141 €, 0.027 €, and 1.356 €, respectively. Conversely, daily economic savings are calculated to be 3.62 €, 2.49 €, 5.05 €, 3.62 €, and 6.70 € for each corresponding energy source. This research underscores the viability of the proposed design in fostering sustainability through both environmental preservation and economic efficiency.

Influence of novel ogive shape ribs and cavities on local flow dynamics and thermal characteristics of microchannel heat sink

This study proposes using novel ogive-shaped ribs and cavities to enhance the thermal performance of a microchannel heat sink (MCHS). A three-dimensional conjugate numerical model was employed to investigate the impact of these modifications, i.e., ogive shape ribs and cavities, on the hydro-thermal performance of MCHS in laminar flow regime (Reynolds number 100–1000). The results show that flow separation occurs on the trailing edge of ogive ribs, promoting convective heat transfer by disrupting the boundary layer and enhancing fluid mixing on the downside of ogive ribs due to the formation of recirculation zones. Conversely, stagnant zones are created inside the ogive cavity due to very low fluid local velocity which results in a decrease of local Nusselt number. The study reports a 41.34% maximum improvement in Nusselt number for MCHS with ogive ribs on side channel walls and a maximum thermal enhancement factor of 1.42 for MCHS with ogive ribs on the bottom channel wall.

Thermal behaviors and flow profiles in a square channel fitted with X–V modified ribs: A numerical analysis

A novel design of “X–V rib” turbulators is proposed to improve fluid blending and to perturb thermal boundary layer (TBL) in a heat exchanger (HX) duct. Better fluid blending and more highly disturbed TBL are the two important factors for the improvement of HX performance. Effects of X–V rib geometrical parameters including rib height ratios (b/H = 0.05–0.20), rib arrangements (V-tip pointing upstream called “V-Upstream (VU)” and V-tip pointing downstream called “V-Downstream (VD)”) and rib types (I, II and III) on air stream and thermal mechanisms are numerically investigated in a 3D model. The numerical model is solved with the finite volume method (a commercial code) and a commercial program. Laminar air flow (inlet conditions with Re = 100–2000) is a selected range of the present investigation. Firstly, the created numerical model for the ribbed duct is validated with two significant topics: 1. Plain duct validation and 2. Optimum grid elements (grid independence). The validated results show that the ribbed-duct model has great reliability to simulate air stream and thermal characteristics. According to the numerical results, the disturbed TBL is obviously found in all rib types. Moreover, it is observed that the core flow disturbance occurs and improves fluid blending. The outcomes from the present investigation point out that the knowledge about flow structure and thermal mechanism are important guidelines for the development of vortex turbulators and HX improvement. For the thermal assessments, it is found that the best Nusselt number ratio (Nu/Nu0) is 11.80 for the type III X–V rib with b/H = 0.20 in the VD-direction. Additionally, the maximum thermal enhancement factor within our investigated range is 3.48 at Re = 2000, b/H = 0.20, type II X–V rib in the VU-direction.

Flow and heat transfer profiles in a heat exchanger tube equipped with X-V baffles (XVB): A numerical analysis

Simulations of laminar air flow and thermal configurations through a heat exchanger tube (HXT) equipped with X-V baffles (XVB) are performed. The Reynolds number is between 100 – 2000. The current numerical problem is solved by a numerical method (the finite volume analysis). Effects of the XVB sizes, the XVB distances and the flow directions on the flow and thermal profiles are discussed. The XVB size (b/D) is set between 0.05 – 0.20 and the XVB distance (P/D) is set to 1, 1.5 and 2. X-axis is the flow axis. The positive and negative x-axis are investigated. Two baffle configurations (Type I and II) are compared. The streamlines, vortex flows, temperature profiles and Nusselt number profiles in the HXT installed with these two XVB configurations (Type I and II) are described. The variations for the friction factor ratio (f/f0), Nusselt number ratio (Nu/Nu0) and thermal enhancement factor (TEF) within the HXT equipped with the XVB are presented. In addition, the TEF of 4.07 is found to be the best value for the present investigation.

Performance improvement of a double tube heat exchanger using novel electromagnetic vibration (EMV) method in the presence of Al2O3-water and CuO-water nanofluid; An experimental study

In this research, the novel approach of the electromagnetic vibration (EMV) method was utilized for the first time to increase heat transfer in a double-tube heat exchanger (DTHEX). In this method, a magnetic turbulator (comprising a magnet and an oscillator) was installed inside a central tube that vibrated using an AC magnetic field. The influences of various parameters such as the geometry of the oscillator, magnet position, employing nanofluids, and fluid flow were assessed on the thermal-frictional behavior. The thermal enhancement factor (TEF) was assessed to select the optimal option. The studied options were economically evaluated based on energy efficiency. According to the results, the maximum heat transfer rate could be achieved when the magnet is positioned at 0.374. L from the tube inlet. The highest value observed for overall heat transfer was related to CuO-water 1% nanofluid, which was 277.5% more than simple heat exchanger. Also, the findings showed that heat transfer can be increased up to 13.3 times the energy used and reached to TEF = 3.92, which is a very significant number. Regarding the high potential of the EMV in reaching high thermal performance, it can be utilized as a game changer to save materials, energy, and compaction of the heat exchangers and solar systems.

Enhanced heat transfer performance of sic/water and MWCNT/water nanofluids in micro-cylinder groups

The heat transfer enhancement and the flow characteristics of Multi-Wall Carbon Nanotubes and Silica water-based nanofluids inside micro-cylinder groups are analyzed based on numerical investigations. The simulations of the flow over thirty circular cylinders in an inline arrangement were carried out at low Re numbers (below 300) and volume concentrations ranging from 0.01 to 0.08. The primary objective of this study is to evaluate the Influence of nanofluids on heat transfer enhancement inside micro-cylinder groups. The finite volume method was employed to investigate the effect of nanoparticles, volume concentration, and Re number on the flow and thermal enhancement. The analysis of the resulting pressure drops, Nusselt number variation, temperature distributions, and thermal enhancement factor suggest that the pressure drop and Nusselt number increased with the Reynolds number for both nanofluids. This augmentation is caused by the interaction between the nanoparticles and the wall. Additionally, it was observed that the thermal enhancement factor exceeded 1 at lower nanoparticle concentrations. Notably, the SiC/water nanofluid demonstrated the most significant improvement in heat transfer at a volume concentration of 2%.

Numerical investigation of microchannel heat sink with novel ogive shape ribs

In this study, 3D numerical conjugate heat transfer modeling is used to investigate the thermal and hydraulic characteristics of the microchannel heat sink (MCHS) with different configurations of novel ogive shape ribs on channel walls. It was found that new proposed MCHS configurations with ogive ribs have a high Nusselt number as compared to the smooth MCHS because ogive ribs enhance the heat dissipation between channel walls and fluid by continuously interrupting the thermal boundary layer development. MCHS configuration with ogive ribs mounted on bottom wall improves the Nusselt number of smooth MCHS by 1.13–1.87 times, while MCHS with ogive ribs mounted on both side walls and MCHS with ogive ribs mounted on bottom channel wall improve Nusselt number by 1.12–1.70 and 1.08–1.59 times, respectively, at Re 100–1000. In terms of thermal enhancement factor criterion, the MCHS with ogive ribs on side walls shows superior performance at Re 100–300 and has the highest thermal enhancement factor. While MCHS with ogive ribs on bottom wall outperformed other configurations in terms of thermal enhancement factor at Reynold number > 300. A maximum thermal enhancement factor of 1.42 is reported for MCHS with bottom wall ribs ogive at Re = 1000.

Heat transfer enhancement of a copper tube with constant wall temperature using a novel horizontal perforated teardrop-shaped turbulators (PTST)

Considering that turbulators generally have a high pressure drop level and as a result low thermal performance, in this research a numerical study conducted for a new form of aerodynamically designed turbulators that are concentrically perforated to have less pressure drop. In this study, the effects of a novel perforated teardrop-shaped turbulator (PTST) on the hydro-thermal parameters were numerically examined. Results were compared with a plain tube and a tube equipped with a simple teardrop-shaped turbulator (STST). PTST with the horizontal perforation geometry including a square, hexagon, octagon, and circle holes was installed inside a copper tube with constant wall temperature. The effect of the horizontal perforation cross-section area on the heat transfer and pressure drop was also evaluated. Tests were conducted under turbulence flow rates in the range of 0.044–0.099 kg/s. To select the optimal case, the thermal enhancement factor (TEF) was calculated. The results clarified that the hole area and hole geometry have a significant effect on TEF and hydro-thermal parameters. The highest heat transfers and pressure drop took place in the presence of the STST, while the highest TEF was equivalent to 1.39 and occurred in the presence of a PTST with a 5 mm diameter circular hole. The heat transfers in the presents of STST and PTST increased by 310.1% and 298% compared to the plain tube. Finally, a correlation expressing the relationship of TEF and perforation area was also presented based on curve fitting.