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This study presented a novel liquid-cooled heat sink based on constructal theory. An experiment was conducted to investigate the influence of boundary conditions, such as the mass flow rate (m ̇) , on heat transfer rate (Q in) and pressure drop. Five cylinder heater cartridges were used in the experiment for 11 different mass flow rates (0.008292 < m ̇ (kg/s) < 0.03307). Through numerical simulation, the effects of changing the number of clusters on heat transfer and pressure drop were studied. The results showed that the optimal combination of pressure drop and Nusselt number occurs in four clusters. According to the results, increasing the number of clusters can increase the Nusselt number by up to 11.98% and 13.62% for the highest (m ̇ = 0.03307 kg/s) and lowest (m ̇ = 0.008292 kg/s) mass flow rates, respectively. This work may lay the foundation for creating the next generation of thermal management systems for compact heat sources, such as the CPU in a self-driving car, robots and high-performance computers (HPC). [ABSTRACT FROM AUTHOR]

We studied the effect of fin patterns on the air-side performance of a novel type of heat exchanger, namely louver spiral fin-and-tube heat exchangers (LSFTHXs). We investigated three types of fin patterns—radial, curved, and mixed-louver spiral fins—and compared their characteristics with plain spiral fin. We fabricated heat exchangers with a crimped aluminum fin base, two rows of steel tubes, and a fin pitch of 8.45 mm. All heat exchangers had both multipass parallel and counter cross-flow arrangements. The average heat transfer rate (Q ave), heat transfer coefficient (h o), and pressure drop (ΔP) increased along with frontal air velocity. The louver-spiral fin provided greater Q ave and h o than plain-spiral fin by about 9.7–15.6% and 13.4–27.1%, respectively. The j factors (Colburn factors) of louver-spiral fins were greater by approximately 10.4–13.1% (for mixed LSFTHX), 7.7–8.8% (for radial LSFTHX), and 2.1–5.1% (for curved LSFTHX) compared with the plain SFTHXs. Additionally, we found no significant difference in ΔP or f factor (friction factor) between louver-spiral and plain-spiral fins. LSFTHX configurations increased h o and j. [ABSTRACT FROM AUTHOR]

An investigation was experimentally performed to explore the influence of geometrical parameters on the evaporative heat transfer coefficient and pressure drop of R-134a in dimpled tubes. The test sections were the counter-flow tube-in-tube heat exchanger, where the refrigerant was evaporated in the inner tube and hot water flows in the annulus. Seven dimpled tubes with various helical pitches (p), dimpled pitches (z), and dimpled depths (e) were used as the test tubes. The test runs were carried out over mass fluxes of 300, 400, and 500 kg/m2s; heat fluxes of 20, 25, and 30 kW/m2; and evaporating temperatures of 7, 10, and 13 °C. The results show the heat transfer enhancement factor (HF) and pressure drop penalty factor (PF) increase with a rise in e and a decrease in p and z. The HF and PF range between 1.03–1.7 and 1.76–9.00, respectively. The correlations for predicting the Nusselt number and the friction factor of R-134a during evaporation in dimpled tubes are proposed. [ABSTRACT FROM AUTHOR]

Highlights • Heat transfer and pressure drop of R-134a in dimpled tubes are investigated. • The effects of dimpled depth on the heat transfer and pressure drop are examined. • The heat transfer enhancement factor is up to 1.81 times of smooth tube. • The correlations to predict the Nusselt number and friction factor are proposed. Abstract An experimental investigation is conducted to determine the effect of dimpled depth on the condensation heat transfer coefficient and pressure drop of R-134a flowing inside dimpled tubes. The test condenser is a double tube heat exchanger where the refrigerant flows inside and water flows in the annulus. The inner tube is a 1500 mm long and 8.1 mm inside diameter. The experiments are carried out for one smooth tube and three dimpled tubes having dimpled depth of 0.5, 0.75, and 1.0 mm. For each test tube, several test runs are performed over mass flux range of 300–500 kg/m2s, heat flux range of 10–20 kW/m2, and condensing temperature range of 40–50 °C. The experimental results reveal that the dimpled tube presents the significant heat transfer enhancement and pressure drop penalty. The tube with the highest dimpled depth yields the highest heat transfer enhancement and pressure drop penalty up to 83% and 892% higher than those of the smooth tube, respectively. Additionally, the overall performance of dimpled tube is evaluated in term of efficiency index. The new correlations including the effect of dimpled depth, dimpled pitch, and helical pitch on the Nusselt number and friction factor of R-134a in dimpled tube are developed. [ABSTRACT FROM AUTHOR]

In this study, a comparison of the convective heat transfer, pressure drop, and performance index characteristics of heat sinks with a miniature circular pin-fin inline arrangement (MCFHS) and a zigzag flow channel with single cross-cut structures (CCZ-HS) is presented. SiO2-water nanofluids with different particle concentrations are used as the coolant. The effects of the heat sink type, particle concentration and fluid flow rate on the thermal and hydraulic performances are evaluated. The testing conditions are performed at the wall heat fluxes of 10 to 60 kW/m2 and at a mass flow rate ranging from 0.18 to 0.6 kg/s. The dimension of heat sinks is equally designed at 28 × 33 mm. The heat transfer area of MCFHS and of CCZ-HS is 1430 and 1238 mm2, respectively. Similarly, the hydraulic diameter of the flow channel of MCFHS and of CCZ-HS is 1.2 and 1.0 mm, respectively. The measured data indicate that the cooling performances of CCZ-HS are about 24-55% greater than that of MCFHS. The effects of the channel diameter and single cross-cut of the flow channel are more dominant than the effects of the fin structure and heat transfer area. [ABSTRACT FROM AUTHOR]

The heat transfer enhancement and pressure loss penalty of condensing refrigerant R-134a in dimpled tubes with different helical and dimpled pitches are experimentally investigated. The test section is a 1500-mm-long tube-in-tube heat exchanger placed horizontally. The inside and outside diameters of the inner tubes are 8.1 and 9.52 mm, respectively. One smooth tube and five dimpled tubes with different helical and dimpled pitches are tested. The experimental runs are done at saturated condensing temperatures ranging from 40 to 50 °C. The mass fluxes and heat fluxes vary from 300 to 500 kg/m 2  s and from 10 to 20 kW/m 2 , respectively. The results show that the dimpled tubes yield higher heat transfer enhancement and pressure drop penalty compared to the smooth tube under the same operating condition. By decreasing helical and dimpled pitches, both the heat transfer coefficient and frictional pressure drop increase significantly. The maximum heat transfer coefficient and frictional pressure drop are achieved through the tube with the lowest helical and dimpled pitches (p = 5.08 mm, z = 3.24 mm) up to 88% and 630% higher than those of the smooth tube, respectively. The new correlations for predicting the Nusselt number and friction factor of R-134a condensing in dimpled tubes with different helical and dimpled pitches are proposed. [ABSTRACT FROM AUTHOR]

This study investigates the heat transfer and pressure drop of R-134a during condensation inside a dimpled tube. The test section is a horizontal counter-flow double-tube heat exchanger with refrigerant flowing in the inner tube and cold water flowing in the annulus. The inner tubes consist of one smooth tube and one dimpled tube, which are made from copper. The length and inner diameter of the test tube are 1500 mm and 8.1 mm, respectively. The test runs are performed at saturation temperatures of 40, 45, and 50 °C, heat fluxes of 10, 15, and 20 kW/m 2 , and mass fluxes of 300, 400, and 500 kg/m 2 s. The effects of heat flux, mass flux, and saturation temperature on the heat transfer coefficient and frictional pressure drop are examined. Comparisons between smooth and dimpled tubes on the heat transfer and frictional pressure drop are also discussed. It is observed that the heat transfer coefficient and frictional pressure drop obtained from a dimpled tube are higher than that of the smooth tube. In addition, as the equivalent Reynolds number increases, the dimpled tube enhances the Nusselt number around 1.3–1.4 times in comparison to the smooth tube. Whereas, when the equivalent Reynolds number decreases, the two-phase friction factor rises around 2.8–4.1 times as compared to the smooth tube. [ABSTRACT FROM AUTHOR]

The paper reports an experimental investigation into the thermal performance and pressure drop characteristics of nanofluid-cooled heat sinks and then compares the results with the data for water-cooled heat sinks. Heat sinks with miniature circular-fin (MCFHS) and square-fin (MSFHS) structures are used and made from aluminum material with dimensions of 28 × 33 mm. Similarly, SiO 2 nanoparticles dispersed in deionized water with particle concentrations of 0.2%, 0.4%, and 0.6% volume are used as working fluids. The effects of pin fin configuration, particle concentration, and flow rate on the heat transfer performance and flow behaviors are presented. Reynolds numbers based on the hydraulic diameter of each flow channel ranging between 700 and 3700, fluid temperature of 15 °C, and heat flux ranging from 2 and 5 W/cm 2 are tested. Hydraulic diameters based on each flow channel are equally designed at 1.2 mm for both heat sinks. The experimental results indicate that the heat transfer coefficient increased with increasing Reynolds numbers and particle concentrations. The MCFHS gave greater heat transfer performance than that of the MSFHS by about 6–9%. For pressure drop data, the measured data showed that the pin fin configuration and particle concentration had small effects on the pressure drop and pumping power. [ABSTRACT FROM AUTHOR]

Highlights: [•] Effect of the free rotation of a swirl device is investigated. [•] Five swirl generators are installed equally distant along the test section. [•] Data of fixed turbine and freely rotating turbine are compared. [•] The performance for rotating turbine is 6.3% higher than that for fixed turbine. [•] The tube with RTSG inserts gave the lowest pressure drop. [Copyright &y& Elsevier]

Abstract: Heat transfer enhancement and flow behaviors in horizontal circular tubes installed with five rotating turbine-type swirl generators (RTSG) are presented experimentally. This type of RTSG is an innovative design that has not been seen in the previous research. Deionized water is used as a working fluid and flows through the test section under turbulent flow conditions. A smooth, stainless steel tube 9.2mm in ID, 0.4mm in thickness, and 2.3m in length is used as the test section. RTSG made from aluminum, with a twisted angle of 60° and a length of 2cm, are located at 0.46m equally distant along the test section. When fluid flows through the RTSG, continuously free rotations are observed, and swirl flow after RTSG is created. A DC power supply is used to supply heat load to the test section. Compared with a common, plain tube (without rotating swirl devices), the experimental results indicate that the local heat transfer coefficient of the tube with RTSG inserts is higher than that of the common, plain tube, and they increase when the working fluid flows through the RTSG. Similarly, the wall temperatures of the tube with RTSG inserts are lower than those of the common tube. However, the pressure drop of the tube fitted with RTSG is significantly greater than that of the common, plain tube. [Copyright &y& Elsevier]

Abstract: New correlations of the two-phase multiplier and heat transfer coefficient of R134a during evaporation in a multiport minichannel at low mass flux are proposed. The experimental results were obtained from a test using a counter-flow tube-in-tube heat exchanger with refrigerant flowing in the inner tube and hot water in the gap between the outer and inner tubes. Test section is composed of the extruded multiport aluminium inner tube with an internal hydraulic diameter of 1.2mm and an acrylic outer tube with an internal hydraulic diameter of 25.4mm. The experiments were performed at heat fluxes between 10 and 35kW/m2, and a refrigerant mass flux between 45 and 155kg/(m2 s). Some physical parameters that influenced the frictional pressure drop and heat transfer coefficient are examined and discussed in detail. The pressure drop and heat transfer coefficient results are also compared with existing correlations. Finally, new correlations for predicting the frictional pressure drop and heat transfer coefficient at low mass fluxes are proposed. [Copyright &y& Elsevier]

Flow pattern, heat transfer, and pressure drop data for different flow orientations was presented in this study. The data was obtained based on flow boiling experiments with R-134a flow through a 1 mm diameter channel which was aligned in different orientations, i.e. horizontal flow, vertical upward flow, and vertical downward flow. A constant surface heat flux condition was performed under a saturation pressure of 8 bar, a heat flux range of 1–60 kW/m 2 , and a mass flux range of 250–820 kg/m 2 s. The experimental results showed the importance of the change in the flow direction. The shape of the gas slug during horizontal flow did not look the same as in the vertical orientations. Heat transfer coefficient and pressure drop became increased when the refrigerant flowed in the vertical downward direction. The experimental data was also compared with the existing prediction methods. [ABSTRACT FROM AUTHOR]

• Condensation flow of R-134a and R-513A in a horizontal smooth tube is studied. • Condensation flow of R-513A in horizontal smooth and micro-fin tubes is studied. • R-513A can replace R-134a with a lower heat transfer coefficient and pressure drop. • The micro-fin tube can enhance the heat transfer coefficient by 69 %. • The enhancement in pressure drop for a micro-fin tube is up to 120 %. An experimental investigation to determine the average heat transfer coefficient (h av) and frictional pressure drop (ΔP F) characteristic of R-513A and R-134a in a smooth tube (ST) and micro-fin tube (MFT) is carried out. A 2500 mm long counter-flow tube-in-tube heat exchanger made of copper is used for conducting experiments. The ST and MFT with inner diameters (D i) of 6.74 and 6.82 mm, respectively, are experimentally tested for various operating conditions such as saturation temperatures (T sat = 40 to 50 °C), heat fluxes (q" =9.8 to 19.6 kW/m2), mass fluxes (G = 575 to 770 kg/m2s) and average vapor qualities (x av = 0.2 to 0.9). The influence of q", G, and T sat on h av and ΔP F are discussed. First, a comparison between R-513A and R-134a in an ST showed maximum reductions of 16 and 20 % in h av and ΔP F, respectively for R-513A, when compared to R-134a. Second, the MFT, due to its higher heat transfer area, resulted in 69 % and 120 % enhancements in h av and ΔP F , respectively, compared to that of an ST. Hence, the findings of this research provide information that is currently useful to the thermal industries, affirming that R-513A can be a suitable long-term alternative refrigerant. [ABSTRACT FROM AUTHOR]

In this work, heat transfer and pressure drop characteristics of nanofluids flowing through a horizontal circular tube have been investigated experimentally. The test tube was made of stainless steel type 304 with an inner diameter of 7.1 mm. The working fluid was SiO 2 /water nanofluid where the average diameter of nanoparticles was 7 nm. Nanofluids at three different volume concentrations of 0.5, 1, and 2% have been prepared and tested. The experiments have been performed for Reynolds numbers ranging from 3800 to 12000, inlet temperatures of 25, 30, and 35 °C where a constant heat flux was imposed on the tube. The effects of particle volume concentrations, inlet temperature and mass flow rate on convective heat transfer and pressure drop characteristics have been evaluated. The results revealed that with increasing Reynolds number, volume concentration, and inlet temperature the heat transfer coefficient and Nusselt number increased. Moreover, pressure drop increased with increasing volume concentration; conversely, decreased with increasing inlet temperature. The efficiency index reached its maximum quantity (i.e. 1.6) at Reynolds numbers higher than 9000, the volume concentration of 2%, and inlet temperature of 35 °C. On the other hand, the minimum values of efficiency index were obtained for Reynolds numbers less than 7000, the volume fraction of 0.5%, and inlet temperature of 25 °C. Finally, new correlations for predicting the Nusselt number and friction factor of SiO 2 /water turbulent flow have been proposed. [ABSTRACT FROM AUTHOR]

• The alternating cross-section flattened having a small-sized tube is examined. • Two-phase flow inside this tube is the first experimental study. • The effective parameters for thermal performance are discussed. • Alternating cross-section flattened tube shows an outstanding performance. • New correlations for predicting N u and f T P are proposed. This work presents the experimental study of two-phase flow inside an alternating cross-section flattened (ACF) tube. The ACF tube was made from a copper circular tube with an inner diameter of 4.31 mm. We conducted the test under the following experimental conditions: a mass flux of 280, 430, and 580 kg/m2s; a saturation temperature of 40, 45, and 50 °C; a heat flux of 10, 15, and 20 kW/m2; and an average vapor quality of 0.1–0.8. Compared to the existing flow pattern maps, most fell into the annular and semi-annular flow regimes. However, the results were found in the transition and intermittent flow regions at low vapor quality. The results from the circular and ACF tubes were examined and discussed. We found that the ACF tube revealed a prominent condensation heat transfer coefficient and a reasonable pressure loss penalty. The heat transfer coefficient and frictional pressure drop of the ACF tube were higher than that of the circular tube by approximately 25.6–111.1% and 4.3–39.9%, respectively. New correlations for the Nusselt number and two-phase friction factor were proposed. [ABSTRACT FROM AUTHOR]

Owing to the generalization problem, there aren't sufficient empirical correlations for two-phase flows. So as to investigate the thermal features of the two-phase flow in smooth and enhanced tubes, a suitable procedure of the models and correlations related with the heat transfer coefficients, friction factors and two-phase multipliers are needed because a significant variation in thermal properties happens during phase-change. Comparison of frictional pressure drop of R134a during flow boiling phenomena occurred in a smooth and 5 enhanced tubes with well-known empirical correlations were performed in this study. The apparatus has 0.85 m long double tube for vertical configuration as a test section that includes smooth and corrugated copper tubing having inner diameters of 0.0087 m, and the range of mass fluxes are between 200 and 400 kg m − 2 s − 1 . The average vapor qualities vary from 0.14 to 0.86, and saturation pressure interval is between 4.5 and 5.7 bar. The mean boiling heat transfer coefficient of R134a is determined via energy balance in the test section. The estimation performance of 36 empirical correlations in literature proposed for convective boiling flows in smooth and corrugated tubes are evaluated by means of authors' database (350 data points for vertical tubes). Boiling trend lines have been plotted for the change of vapor quality, liquid phase Reynolds numbers with gas phase ones. In addition, the most successful correlations are confirmed their predictabilities for the vertical adjusted evaporator having smooth and corrugated tubes using the database of authors' earlier publications in open sources. [ABSTRACT FROM AUTHOR]

Lithium-ion battery (LIB) packs with high power density are necessary in battery-powered system development. In this study, we investigated LIB packs made of compact cylindrical Li-ion batteries. We arranged the batteries in various patterns, including square, lozenge, elliptical, and circular, with all patterns occupying the same total area. We solved the thermal and electrochemical equations governing the batteries using the finite-element method (FEM), and we coupled the airflow around the batteries, meant to lower their temperature, with the LIB equations and solved them using the same method. The results reveal that LIB cooling enhancement and a smaller temperature gradient occur with an increase in the LIB distribution at the center, reducing their outward dissemination and shortening the LIB length. Additionally, increasing the cross-sectional area and airflow velocity enhanced heat transfer from the batteries and decreased their temperature. Finally, we demonstrated that better cooling enhances the cells' long-term performance. With a circular configuration, the pressure drop and heat transfer rise by 48.01% and 85.14%, respectively, with an increase in the inlet cross-section area. Furthermore, the pressure drop and heat transfer in this configuration increased by 89.09% and 66.90%, respectively, when the velocity increases. • 36 commercial 21,700 Lithium-ion batteries were considered. • Solving thermo-electrochemical governing equations using Finite element method. • Increasing inlet area and velocity enhanced heat transfer and decreased temperature. • Increasing velocity in circular configuration increased heat transfer by 66.90%. [ABSTRACT FROM AUTHOR]

• Multiports act as internal fins and enhances evaporation rate of working fluid. • Reservoirs at the ends supply required quantity of fluid & reduce fluid entrainment. • Reduction in heat transfer and pressure drop irreversibilities of 17 & 48% observed. • Multiport design showed good stability by withstanding 2.7 bar pressure at 90 W. Thermal performance of an air cooled minichannel thermosyphon having multiports (10 ports) with hydraulic diameter of 1.18 mm is investigated. Experiments conducted at different heat loads (10 to 90 W), filling ratios (40, 50 and 60 %), inclination angles (30, 45, 60 and 90°), confluence lengths (0, 5 and 10 mm) and cooling air velocities (0.8, 1, 1.2 and 1.5 m/s) using acetone as working fluid. Results showed a maximum heat dissipation of 90 W with evaporator wall temperature of 72.2 °C at 5 mm confluence length. Multiports act as internal fins and enhance the surface area of the thermosyphon. This improves the boiling and evaporation rate, leading to reduced thermal resistance and wall temperature. An average reduction of 17.1 and 48.2 % are respectively noted in the irreversibilities of heat transfer and pressure drop at optimum condition. Liquid reservoirs at both ends of the thermosyphon overcomes the entrainment problem and supply the required quantity of working fluid and prevents it from reaching dry out condition. Analysis revealed that, the internal flow pattern transition is between Slug and Geyser flow for the tested heat loads. The present experimental findings can be a useful guide for engineering design to satisfy the requirement of cooling in miniaturized electronic devices. [ABSTRACT FROM AUTHOR]

In this paper, an analytical study is carried out on the heat transfer, pressure drop, and entropy generation in a flat-plate solar collector using Si0 2 lwater nanofluid with volume concentration of 1%. In the study, the effects of two different values of pH, i.e., 5.8 and 6.5, and two different sizes of nanoparticles, i.e., 12 nm and 16 nm, on the entropy generation rate in turbulent flow are investigated. The results are compared with the results obtained for the case of water. The findings show that by using the Brinkman model to calculate the viscosity instead of experimental data one obtains a higher heat transfer coefficient and thermal efficiency than that in the case of water, while, when the experimental data are used, the heat transfer coefficient and thermal efficiency of water are found to be higher than that of nanofluids. The results reveal that using nanofluids increases the outlet temperature and reduces the entropy generation rate. It is also found that for nanofluids containing the particles with a size of 16 nm, the increase in pH value would increase the entropy generation rate, while for nanoparticles with a size of 12 nm the increase in pH would decrease the entropy generation. [ABSTRACT FROM AUTHOR]

This paper is a continuation of the authors' previous work on the thermophysical properties, heat transfer, and pressure drop of nanofluids [Experimental Thermal and Fluid Science 52 (2014) 68–78]. In this paper, an experimental study is carried out to study the turbulent flow of COOH-functionalized multi-walled carbon nanotubes/water nanofluid flowing through a double tube heat exchanger. For this purpose, first, the thermophysical properties of the nanofluid, including the thermal conductivity and dynamic viscosity, have been measured at various temperatures and concentrations. Using the measured data, new correlations as a function of temperature and concentration are presented to predict the thermophysical properties. In the next step, the effects of low volume fractions of the nanofluid (from 0.05% to 1%) on the heat transfer rate are studied at the Reynolds numbers between 5000 and 27,000. The experimental results reveal that with increasing the nanofluid concentration, the heat transfer coefficient and thermal performance factor increase. On average, a 78% increase in heat transfer coefficient, a 36.5% increase in the average Nusselt number, and a 27.3% penalty in the pressure drop are recorded for the highest concentration of MWCNTs in water. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, an experimental study is performed to assess the heat transfer characteristics and pressure drop of low concentrations of a new class of nanotubes, i.e. COOH-functionalized double-walled carbon nanotubes (DWCNTs) suspended in water under turbulent flow in a double tube heat exchanger. First, the thermal conductivity and viscosity of nanofluids at volume fractions of 0.01%, 0.02%, 0.05%, 0.1%, 0.2%, and 0.4% are measured and corresponding correlations are presented. Next, the heat transfer and pressure drop of the nanofluids through the double tube heat exchanger are evaluated. The results indicate that even the use of low concentration of the nanofluid, i.e. 0.4%, leads to a remarkable increase in heat transfer coefficient (by 32%) in comparison with the distilled water. On the other hand, the pressure drop due to using the volume fraction of 0.4% raised by 20%. Finally, analysis of the heat transfer and pressure drop data via thermal performance factor reveals that in spite of the pressure drop penalty, the COOH-functionalized DWCNTs/water nanofluid with volume fraction of 0.4% is a good option to use in the double tube heat exchanger. [Copyright &y& Elsevier]

Abstract: The purpose of this experimental investigation is to investigate the effects of fin pitch (i.e., fp of 2.4, 3.2, and 4.2mm) on the air-side heat transfer performance and frictional characteristics of L-footed spiral fin-and-tube heat exchangers at high Reynolds numbers (Redc ) of 4000–15,000. A determinant of the parallel cross-flow and the counter cross-flow is the flow arrangement of the test heat exchangers. Ambient air and hot water are used as a working fluid on the air- and the tube-side, respectively. The results indicate that the air-side heat transfer coefficient and Colburn factor are independent of fin pitch. However, fin pitch does have an influential effect on the average heat transfer rate, pressure drop, and friction factor. In terms of industrial applications, the correlation of the Colburn factor and friction factor are proposed for practical applications. [Copyright &y& Elsevier]

Heat transfer and pressure drop of turbulent fluid flow were studied numerically and experimentally in a quad-channel with twisted tapes placed in a circular tube under uniform heat flux boundary condition. All the tests were conducted with water as the working fluid where the turbulent flow range of Reynolds numbers were maintained at 4250 to 11000. Quad-channel twisted tapes (QCTT) were manufactured by 3D printer with the material PLA, the lengths of 50 mm, 100 mm, 200 mm with the twist ratio of 4.48. The tapes were identified with their tape/pipe length ratios (TPR) of 0.025, 0.05 and 0.1. Validation of the experimental data was performed by the comparison of the experimental results with the data from the well-known empirical correlations. Alteration of the friction factors and Nusselt numbers with the Reynolds numbers are presented in this paper. The results showed that the Nusselt number and the friction factor increased with the increasing of the length of QCTTs. On the other hand, the performance evaluation criteria (PEC) should be declining with the increase of the lengths of the tapes. The evaluated temperature distributions inside the tested tubes with the inserts were plotted in order to investigate the observed data. Based on the obtained experimental data, the empirical correlations for the Nusselt number within the deviation of ±2% and the friction factor within the deviation of ±5% were developed for the practical usage. [ABSTRACT FROM AUTHOR]