Highest Thermal Hydraulic Performance Research Articles

Mitigation of fouling with swirling flow induced in 3-D double-sided straight channel for printed circuit heat exchanger

Fouling should be considered in the design of a printed circuit heat exchanger (PCHE) for industrial applications. The swirling flow, which is known to mitigate fouling in heat exchangers, can incorporate this aspect; however, realizing these flow characteristics in compact heat exchangers such as PCHE is difficult. Thus, this study proposed a three-dimensional (3-D) designed PCHE channel. To induce swirling flow, it was designed to face two semicircular straight channels with angles such that the interaction between the mainstreams in different flow directions induced a swirling flow. Compared to conventional two-dimensional (2-D) PCHE channels (straight, zigzag, and airfoil channels), the swirling flow induced in the proposed 3-D PCHE channel uniformly increased the wall shear stress while minimizing flow separation or recirculation. This minimized the low wall shear stress that was more likely to be fouled. A comparative evaluation of the thermal-hydraulic performance of the investigated channels was conducted by comparing the volume goodness factors under the equal hydraulic diameter. The proposed 3-D channels exhibited the potential to mitigate fouling, as well as a thermal-hydraulic performance comparable to that of conventional 2-D PCHE channels. Therefore, the proposed 3-D channel can be suggested as an advanced PCHE design option for high thermal-hydraulic performance and mitigation of fouling. Furthermore, because the swirling flow is known to mitigate fouling in heat exchangers as well as the heat transfer deterioration of sCO2, a double-sided straight channel with swirling flow is expected to be competitive.

Effects of Channel Flow Blockage on Metal Foam Heat Transfer

Abstract High porosity aluminum foams have the potential to dissipate large heat flux in a channel flow configuration due to their large surface area-to-volume ratio and the ability to enhance mixing due to flow tortuosity. It is well documented that the interstitial heat transfer coefficient has a power law dependence on the flow velocity at the pore-scale. For asymmetrical heating (single wall), a flow blockage concept is proposed with an aim to locally enhance flow speed near the heated wall. To this end, experimental and numerical investigation is carried out on a high porosity (95%) aluminum foam (10 pores per inch) with flow blockages, both upstream and downstream of the metal foam placed in a square channel. The opening was provided closer to the heated wall, where flow blockage was varied from 0% to 87%. With air as working fluid, experiments were conducted for channel Reynolds number varying from 3000 to 13,000. It was found that all flow blockages resulted in enhanced heat transfer over no-blockage case, however, at a high pressure drop penalty. An upstream flow blockage of 70% was found to have the highest thermal-hydraulic performance among other flow blockages (including 0% blockage).

Experimental investigation on comprehensive thermal-hydraulic performance of supercritical CO2 in a NACA 0020 airfoil fin printed circuit heat exchanger

Printed circuit heat exchanger (PCHE) is a promising compact heat exchanger for supercritical CO2 power conversion systems. Among the channel shapes of PCHE, an airfoil fin channel was considered for the high thermal-hydraulic performance of the PCHE. However, quantitative experimental evaluation of the thermal-hydraulic performance between the optimized airfoil fin and the wavy channel (commercially utilized channel shape) has not been performed. Therefore, in this study, to compare the performance according to channel shape, experiments on the optimized arrangement of airfoil fin PCHE (NACA 0020 airfoil fin with non-dimensional arrangement parameters, staggered number 1.0, horizontal number 2.0, and vertical number 1.8) and wavy PCHE (120° bending angle) were conducted. The experimental conditions of supercritical CO2 were temperatures ranging from 70°C (inlet) to 40.5°C (outlet) with pressures varying from 7.5 to 8.5 MPa. To reflect the real etched shape of airfoil fin channel, the real shape of airfoil fin was measured by using optical 3-Dimensional scanner. And hydraulic diameter was calculated based on measured information of real etched airfoil fin shape. The pressure drop of the airfoil fin PCHE was one-fifth of that of the wavy PCHE with the same total heat transfer rate per unit volume. New empirical correlations for the friction factor and Nusselt number of the airfoil fin PCHE were proposed based on the experimental data for the precooler design in the supercritical CO2 Brayton cycle. A friction factor correlation with maximum deviations of ±5.04 % and Nusselt number correlation with maximum deviations of ±14.0 % were proposed.

Recent Progress in Flow Control and Heat Transfer Enhancement of Impinging Sweeping Jets Using Double Feedback Fluidic Oscillators: A Review

Abstract Jet impingement finds an important role in several industrial applications which require high thermal-hydraulic performance of heat exchange systems. The self-exciting sweeping jets produced by fluidic oscillators provide superior thermal and hydraulic performance as compared to plain jets. The fluidic oscillator increases the jet impingement area on the target surface by maintaining a steady and controlled oscillatory flow. The continuous advancements in the design improvement of fluidic oscillators have led to further enhancements of heat and fluid flow characteristics. In this context, double feedback fluidic oscillators have shown promising jet flow control features and jet impingement cooling characteristics. Therefore, the current study has been devoted to analyzing and assessing the recent research progress in design improvements of double feedback fluid oscillators and the augmentation of thermal-hydraulic characteristics of impinging sweeping. Moreover, the variations in the heat transfer and hydraulic performance of impinging jets for different shapes of target surfaces have been comprehensively examined. In the end, research gaps for future work have been highlighted.

Numerical investigation of pentagonal V-shape ribs to enhance heat transfer in hydrogen rocket engine cooling channels

Keeping the combustion chamber walls at a sufficiently low temperature ensures liquid rocket engines' safe and reliable operation. The most promising method to achieve that is the heat transfer enhancement techniques which optimize the heat transfer coefficient and increase the thermo-hydraulic performance. The present work is concerned with numerical studies on the effect of the pentagonal V-shape ribs to enhance the heat transfer coefficient of the rocket engine's cooling channels. Numerical simulations for various chamfering angels of the pentagonal V-shape rib are performed by the (SST,k−ω) turbulent model. The simulation findings show that the overall performance of the ribbed channel improved inversely with the pentagonal chamfering angle. Compared with a conventional channel, the average Nusselt Number and thermal-hydraulic performance of the ribbed channel enhanced up to 66.6% and 52% respectively, and the 5° pentagonal V-shape rib has higher thermal-hydraulic performance with a slight high the pressure loss penalty.

Numerical analysis of the effect of longitudinal and transverse pitch ratio on the flow and heat transfer of staggered drop-shaped tubes bundle

Several studies have been conducted to enhance the performance of heat exchangers. In the recent decades, shifting from the bluff bodies to more streamlined ones received more attention. The drop-shaped tube is one of the most propitious options for building a better heat exchanger core. This is because of the aerodynamic profile characteristics of the drop-shaped tube. The present work has been conducted to clarify fluid flow and heat transfer across staggered drop-shaped tubes bundle at various longitudinal and transverse pitch ratios. The investigation is performed at Reynolds numbers Re= (1.78–18.72) x103, longitudinal pitch ratios (PL =1.44, 1.54, 1.64, 1.74, 1.84, and 2.04), and transverse pitch ratios (PT =1.24, 1.44, 1.64, and 1.82). Ansys Fluent software package is used to predict the flow pattern around tubes. The RNG k−ε model is selected to evaluate the turbulence effect of the fluid flow. The results showed that an increase in PT significantly affects the heat transfer as compared to PL. An increase in the transverse pitch ratio from 1.24 to 1.82 enhances the heat transfer by 2.18 - 10.53% for the considered Re range. As the Re increases, the average Nusselt number Nu¯ increases and the friction factor f decreases. At a constant PL, the minimum f was varied with Re and PT. The maximum values of the effectiveness ε and the efficiency index η were achieved for (PT = 1.64; PL = 2.04) at Re=1.78 × 103, and (PT = PL = 1.64) at Re> 1.78 × 103. The drop-shaped tubes bundle showed its superiority over a circular one in terms of high thermal-hydraulic performance under the same operating conditions. Finally, generalized Nu¯, f, and ε correlations for the studied models were predicted, providing a useful reference for future studies or for the design of heat exchangers employing drop-shaped tubes.

An experimental investigation on the thermal augmentation of internal endwall in a two-pass duct using an array of delta-winglet vortex generator pair

The present study experimentally demonstrates a novel design for an internal endwall in a two-pass duct heat exchanger. An array of delta-winglet vortex generator pairs with different aspect ratio, angle of attack, configuration are mounted on the internal endwall in a U duct. Liquid crystal thermalgraphy and static pressure measurements are utilized in this study to evaluate the heat transfer, thermal-hydraulic performance, and pressure drop penalty. The Reynolds number is varied from 10,000 to 20,000. A comparison between the current novel design and traditional enhanced heat transfer turbulators in the open literature is also included. The results show that the endwall heat transfer is enhanced greatly as the longitudinal vortex generator array is located on the endwall. The variation of the attack angle has great influence on the endwall heat transfer, The endwall fitted with turbulators with an aspect ratio (length/height) of 2 and attack angle of 45-deg provides the highest thermal-hydraulic performance with a relatively low pressure drop penalty as long lasting longitudinal vortices might be induced at this attack angle and the heat transfer is observed to be enhanced at the downstream part of the endwall. In addition, for the temperature uniformity on the endwall, the local heat transfer at the upstream part still has the potential to be further improved for all studied cases. The optimal thermalhydraulic performance is increased by more than 24% compared with that on the endwall in the smooth U duct. This novel design presents a rather high overall thermal performance compared with the traditional design in the open literature.

Air-Cooled Loop Thermosyphon Cooling System for High Heat Load CPUs—Part I: Design and Performance Simulation

This article proposes and evaluates the thermal-hydraulic performance of a compact, lightweight, and high heat-transfer capacity cooling system for central processing unit (CPU) temperature control. The cooling loop, defined as a closed loop thermosyphon (LTS), has a passive flow driven mainly by the buoyancy in the riser. It is a self-modulated system, i.e., without heat flow ceases but it increases with increasing heat load. The LTS is a partially passive system since energy is still required to drive the fan blowing air through its condenser. The main advantage relative to conventional forced air-cooled heat spreaders is its ability to transfer much higher levels of heat while consuming less fan power. The innovative patented LTS system has two thermosyphon loops working in parallel, composed of a multimicrochannel evaporator, a multiport tube louvered fin condenser, two risers, and one downcomer. The simulations show that it is able to cool 600 W from a 50 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 50 mm CPU footprint without dryout or surpassing the critical heat flux. It was specifically simulated for a CPU of 2U server, considering a height of only 66 mm and width of 214 mm. Thus, two of these units can be installed side-by-side in a 2U server, which means a total cooling capacity of 1200 W per server. Several simulations are presented showing the high thermal-hydraulic performance of the LTS and a case study showing the reduction of fan energy consumption when comparing the proposed LTS with an actual air-cooled heat spreader system. The LTS was prototyped, experimentally tested, and its simulations successfully validated in Part II of this study.

Improvement in thermal hydraulic performance by using continuous V and W-Shaped rib turbulators in gas turbine blade cooling application

Power output and efficiency of a gas turbine can be improved by employing ribs that have the potential to generate high Thermal Hydraulic Performance (THP). The objective of this experimental work is to achieve high THP in a narrow cooling passage adjoining the leading edge where the operating temperatures are high. To achieve this objective, experiments are conducted in a single-pass cooling channel having aspect ratio (AR) 1:4 and hydraulic diameter (Dh) 0.048 m with V and W-ribs placed on opposite walls facing downstream. Angle-of-attack (α) for the ribs is 45° and the blockage ratio (e/Dh) for V-ribs is 0.0729 and for W-ribs is 0.0833. Pitch-to-height ratio (P/e) for V-ribs is 10 and W-ribs is 8.75. For the Reynolds number range 20000–80000 investigated, V and W-ribs produced high heat transfer enhancements. Maximum Nusselt number ratios for V-ribs and W-ribs are 3.9 and 3.8. Variations in heat transfer along the span and stream are found to be higher for V-ribs and W-ribs respectively. For both the cases, influence of ribs on heat transfer and friction is observed to be highest at Reynolds number 40000. Maximum THP values achieved for V-ribs and W-ribs are 3.3 and 3.

Influence of co/counter arrangements of multiple twisted-tape bundles on heat transfer intensification

Heat transfer intensification in tubes containing multiple twisted-tape bundle inserts was experimentally investigated. The experimental parameters included the tape numbers (N) of 2, 4 and 6 pieces, tape twist ratios (y/w) of 4.0, 5.0 and 6.0) and two different tape arrangements: co-swirl tapes (CoT) and counter-swirl tapes (CT). The tests were carried out using air as the working fluid under a constant heat flux. The experimental results showed that all multiple twisted tape bundles caused higher heat transfer rates, pressure losses and thermal hydraulic performance than a typical twisted tape. The heat transfer rate (Nu) and friction factor (f) increased with the number of tapes (N) and decreased with the twist ratio (y/w). At similar operating conditions, the counter-swirl flow twisted tape sets (CT) provided higher heat transfer (Nu) and friction factors (f) than the co-swirl flow sets (CoT). The highest thermal hydraulic performance (η) of 1.33, was offered by the twisted tapes having y/w = 4.0 and N = 6 at Re = 6000.

Numerical analysis for thermo-hydraulic performance of staggered cross flow tube bank with longitudinal tapered fins

Cross flow tube bank is an important constituent in most of the industrial heat exchanging systems such as Heating Ventilation and Air Conditioning (HVAC) systems, Waste Heat Recovery systems and Industrial Boilers. Considering the depletion of fossil fuels and allied environmental concerns, there is a huge need for improving the performance of the cross flow tube bank. The present numerical study investigates the effect of longitudinal taper fins on external flow over staggered cross flow tube bank. The longitudinal fins of various length (0.50 ≤ L/D ≤ 1.50), base thickness (0.40 ≤ T/D ≤ 0.80) and end thickness (t/D = 0.12 and 0.28) are used to evaluate the thermal performance of the tube bank. The thermal hydraulic performance is evaluated considering the effects on rate of heat transfer along with pressure drop characteristics across the tube bank. The results shows that the use of longitudinal taper fins significantly enhances the thermal hydraulic performance of cross flow tube banks. Moreover, the increase in length of fin results in an appreciable enhancement in Nusselt number, which overrules the increase in pressure drop penalty. Whereas, the increase in the fin base thickness, results in a significant reduction in pressure drop capable of compensating the reduction in Nusselt number. Hence, increase in both these dimensions results in higher thermal hydraulic performance than the bare tube bank. On the other hand, fin end thickness plays only a minor role in the finned tube bank performance. Lowering the value of fin end thickness slightly increase the thermal performance by suppressing the friction factor.

Heat and flow characteristics of V-shaped protrusion/concavity combined with miniature V-ribs

Heat and flow characteristics of V-shaped protrusion/concavity combination with miniature V-rib has been investigated numerically at flow Reynolds number of 50,000. With suitable baseline studies, a total of six different configurations viz. (a) V-rib only, (b) ‘V-rib and V-protrusion’, (c) ‘V-rib and V-concavity’, (d) V-protrusion only, (e) V-concavity only, (f) Sparse V-rib, were studied in a square channel with the above features installed on single wall. With air as the working fluid, the heat transfer mechanism and pressure drop characteristics were compared for all the configurations. The compound configuration of ‘V-rib and V-protrusion’ exhibited the highest thermal hydraulic performance (THP) of 2.15.

Enhanced thermal hydraulic performance by V-shaped protrusion for gas turbine blade trailing edge cooling

Modern high-pressure stage gas turbine blades are equipped with several high-performance cooling concepts, which vary based on the external heat load and the blade-topology. Blade trailing edge cooling is challenging due to the space constraints, where channel aspect ratio (AR: channel width-to-height ratio) is ~ 4:1. With an aim to enhance the thermal hydraulic performance of such narrow channels, a novel V-shaped protrusion configuration is proposed in the present study. The V-shaped protrusion derives its profile from a known concept V-shaped concavity. Numerical investigation of inline configurations of V-shaped concavities and protrusions has been carried out for a 4:1 AR channel for Reynolds number ranging from 10,000 to 60,000. The configurational parameters of both concavity and protrusion were identical. Concavity/protrusion depth-height-to-diameter (δ/D) ratio was 0.3. The streamwise (Sx) and spanwise (Sy) pitch values were 3.2D in both the configurations. The fluid flow and heat transport in the two cooling configurations are discussed in detail. Globally averaged Nusselt number, friction factor and thermal-hydraulic performance have been reported for the investigated Re range. Results show that V-shaped protrusion had the highest thermal-hydraulic performance ~ 2.23, which was about 40.4% higher than the V-shaped concavity configuration for a representative Reynolds number of 10,000.

Jet vortex heat transfer in turbulent air flow around a plate with a slit rib

Experimental study and numerical simulation of vortex heat transfer in turbulent air flow around the plate with permeable transverse rectangular ribs at qw = const have been made. Confusor, diffuser and constant cross-section slits as well as the constant gap between the plate and the lower wall of the rib are considered. Mean and fluctuation profiles of velocity and temperature along the midsection of the plate in the sections of the turbulent boundary layer are measured using both a Pitot–Prandtl microprobe with a microthermocouple and a Dantec Dynamics hot-wire anemometer. To calculate spatial separated flow of incompressible liquids, the Reynolds-averaged Navier–Stokes equations closed by five turbulence models are adopted. The use of the k-ε two-parameter model with the Kato–Lauder modification (SKE-KL) provides a satisfactory agreement between numerical predictions and experimental data. So this model is selected as the basic one. The influence of the throttling effect on the turbulent separated flow structure and relative heat transfer coefficient when changing the slit shape and size is analyzed. The integral characteristics including total heat transfer coefficient, hydraulic losses and thermal-hydraulic performance are also compared. It is shown that the presence of a slit can eliminate secondary separation zones on the plate and decrease recirculation flow regions behind a rib. The rib with a confusor slit has the highest thermal-hydraulic performance that is by 15% more than that of the solid rib.

Thermal-Hydraulic Performance Enhancement by the Combination of Rectangular Winglet Pair and V-Shaped Dimples

Abstract This paper presents numerical study on heat transfer enhancement due to the combination of rectangular winglet pair with V-dimples in an array-type arrangement. Array of rectangular winglet pairs results in heat transfer enhancement, however, at a cost of significant pressure drop, resulting in reduced thermal-hydraulic performance (THP). On the other hand, dimples are associated with lower heat transfer enhancement levels at relatively lower pumping power penalty. To this end, a combination of rectangular winglet pair and V-shaped dimples has been studied in this paper, where the arrangements were intended to achieve enhanced thermal-hydraulic performance. Three different configurations, namely, rectangular winglet pair, rectangular winglet pair with one V-dimple between two consecutive winglets, and rectangular winglet pair with two V-dimples packed in a pitch, are studied here. The variation of heat transfer enhancement, pressure drop gain, and THP with respect to winglet-to-winglet (S) spacing variation for rectangular winglet pair and rectangular winglet pair with one V-dimple configuration is presented at a Reynolds number of 25,000. The THP of the rectangular winglet pair configuration decreases up to S/H equal to 2.5 and then increases (H: channel height). For rectangular winglet pair with one V-dimple, three values of winglet-to-dimple (P) spacings are analyzed. For fixed S/H, the highest P/H configuration provided highest heat transfer enhancement and THP. Among the three configurations studied, rectangular winglet pair with two V-dimples resulted in the highest thermal-hydraulic performance.

Numerical Analysis of Slotted Airfoil Fins for Printed Circuit Heat Exchanger in S-CO2 Brayton Cycle

Recuperator is one of the most important components in supercritical carbon dioxide (S-CO2) Brayton cycle, and the printed circuit heat exchanger (PCHE) has been considered as a promising candidate due to its high efficiency and compactness. The airfoil fin (AFF) PCHE has higher thermal-hydraulic performance than conventional zigzag channel PCHE. However, it also suffers from serious local flow resistance caused by the impact area. Two types of new slotted fins (SFs) based on AFFs including longitudinal slot fins (LSFs) and herringbone slot fins (HSFs) are proposed to release the effect of the impact area. The results show that both LSFs and HSFs can significantly reduce the flow resistance in the channel. Meanwhile, the SFs also show higher thermal performance due to the heat transfer area enhancement by the slots. The LSF channel can be considered as a promising candidate in some energy conversion systems due to its good hydraulic performance, while the HSF channel would behave more efficiently such as in refrigeration cycles due to its high thermal performance. Finally, the field synergy principle is employed to discuss the flow drag reduction in SF channels.

Investigation on the effects of narrowed channel cross-sections on the heat transfer performance of a wavy-channeled PCHE

The printed circuit heat exchanger will play an important role in the field of advanced supercritical carbon dioxide cycle in the future because of its high thermal-hydraulic performance and structural rigidity. In this study, the heat transfer characteristics of a wavy channeled PCHE are numerically investigated and the effects of narrowing channel cross sections on the thermal-hydraulic performance are analyzed. The results show that the heat flux distribution around the channel surface varies periodically and there exist three banded regions with low heat flux for each period, one on the arched surface and two on bottom surface. Narrowing the channel cross section will increase the heat transfer rate per unit volume, making the PCHEs more compact and economic. New empirical correlations of heat transfer and frictional factor are put forward based on the fluid parameters of each period of the channel, and heat transfer correlation can predict the Nusselt number of the PCHE very well with 10% error.

Study on the Thermal-hydraulic Performance of Sinusoidal Channeled Printed Circuit Heat Exchanger

Supercritical carbon dioxide (S-CO2) powers cycles can achieve higher efficiency in a compact footprint and are suitable for various heat sources and have great application potential in a number of energy industry. The printed circuit heat exchanger (PCHE) plays significant roles in the cycles due to its high thermal-hydraulic performance and structure rigidity. In the present study, the thermal-hydraulic performance of sinusoidal channeled PCHE is investigated numerically and compared with that of conventional straight channeled PCHE. The effects of structural parameters of sinusoidal channels on thermal-hydraulic performance are studied in dimensionless manner: the ratio between the amplitude and the period. The results show that the global Nusselt number can be enhanced by 7.4%-13.9%, while the global Fanning friction coefficient increases by 10.9%-16.7% compared to the straight channel. The ratio of amplitude and period significantly influences the performance of sinusoidal channeled PCHE. For the tested operating conditions, both the Nusselt number and the Fanning friction coefficient increase first and then decrease with the ratio. When the ratio is about 0.2, the sinusoidal channeled PCHE offers the highest heat transfer while with the largest pressure drop.

Effect of micro-roughness shapes on jet impingement heat transfer and fin-effectiveness

With recent advancements in the field of additive manufacturing, the design domain for development of complicated cooling configurations has significantly expanded. The motivation of the present study is to develop high performance impingement cooling designs catered towards applications requiring high rates of heat removal, e.g. gas turbine blade leading edge and double-wall cooling, air-cooled electronic devices, etc. In the present study, jet impingement is combined with strategic roughening of the target surface, to achieve high heat removal rates. Steady state experiments have been carried out to calculate the heat transfer coefficient for jet impingement onto different target surface configurations. The jet-to-jet spacing (x/d = y/d) was varied from 2 to 5, and jet-to-target distance (z/d) was varied from 1 to 5. The target surface configurations featured cylindrical, cubic and concentric shaped roughness elements, fabricated through binder jetting process. The baseline case for the roughened target surface was a smooth target. Heat transfer and pressure drop experiments were carried out at Reynolds numbers ranging from 2500 to 10,000. Further, numerical simulations were carried out to model flow and heat transfer for all configurations at a representative Reynolds number. Through our experiments and numerical results, we have demonstrated that the novel “concentric” roughness shape was the best in terms of fin effectiveness and Nusselt numbers levels, amongst the investigated shapes. The concentric-shape roughened target resulted in fin effectiveness up to 1.6, whereas the cubic- and cylindrical-shape roughened targets yielded in fin effectiveness up to 1.4 and 1.3, respectively. Further, it was experimentally found that the addition of micro-roughness elements does not result in a discernable increment in pressure losses, compared to the impingement on the smooth target surface. Hence, the demonstrated configuration with the highest heat transfer coefficient also resulted in highest thermal hydraulic performance.

Experimental study of heat transfer augmentation in a two-pass channel featuring V-shaped ribs and cylindrical dimples

Higher turbine inlet temperature requirements in modern gas turbine airfoils necessitate the development of high performance internal cooling designs for increasing turbine durability and performance. The internal cooling passages of turbine airfoils feature ribs which promote turbulent mixing, increase in near wall shear and hence lead to heat transfer augmentation. One other method of increasing heat transfer enhancement is by adding depressions (commonly called “dimples”) on the walls of internal cooling passages. Earlier studies have investigated different shapes of rib turbulators and dimples, however, the limitations in manufacturability of dimple in actual turbine airfoils has been a concern in the past. Recent advancements in the field of additive manufacturing, e.g. Direct Metal Laser Sintering (DMLS), opens endless possibilities for the development of novel cooling features which can be incorporated in actual engines. The present study investigates the heat transfer and pressure drop characteristics of a two-pass channel (AR=1) featuring ribs-alone, dimples-alone and combination of ribs and dimples. The ribs are V-shaped with rib-height-to-hydraulic diameter ratio of 0.125 and rib-pitch-to-rib height ratio of 16. Dimples are cylindrical in shape and have a depth-to-print diameter ratio of 0.3. The heat transfer coefficient was measured using transient Liquid Crystal Thermography and detailed Nusselt numbers have been reported and analyzed. Also, static pressure measurements were carried out at several locations to determine the total pressure drop across the two pass channel and the local variation of pressure coefficient. The experiments were carried out for a wide range of Reynolds number (19,500–69,000) to cover the full spectrum typically found in both land-based and air-breathing engines. It has been observed that the combination of ribs and dimples resulted in higher heat transfer augmentation as well as higher thermal hydraulic performance when compared with ribs alone and dimples alone configurations for the range of Reynolds number studied.