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AbstractThe efficient thermal management of Lithium-ion batteries (LIBs) stands as a critical factor in ensuring the reliable operation of electric vehicles. For managing multiple LIB modules, a common approach involves utilizing a cold plate for mounting. It has been suggested that this interspersed design proves more effective, especially for large-scale battery packs, in achieving smoother overall cooling performance and temperature uniformity. Consequently, we need a new cold plate design that not only enhances thermal performance for batteries emitting higher thermal loads but also ensures more uniform temperature distributions across battery surfaces, all while maintaining simplicity in manufacturability. In this study, we introduce a new cold plate design employing offset strip fins (OSFs) cores. We assess its thermal and hydraulic performance using objective functions such as the Colburn factor (j) and Fanning friction factor (f). Through optimization techniques, we determine the optimal shape parameters that maximize heat transfer rates on the cold plate, with only a marginal increase in pressure drop. This optimized configuration is then compared with both the baseline common cold plate and a reference OSFs cold plate. The results show a significant reduction of up to 32.3% in maximum temperature differences, signifying an improved temperature uniformity achieved with this new design. [ABSTRACT FROM AUTHOR]

Several measures have been explored to improve the function of plate-fin heat exchangers (PFHEs), including improving heat transfer surface, heat transfer coefficient, finned surface thermal efficiency, and vortex generators. We employ computational approaches in this article to investigate the flow and heat transmission parameters of a plate-fin heat exchanger (PFHE) with a longitudinal vortex generator (LVG) installed on an offset rectangular-triangular fin (ORT), as proposed in a previous work. In order to improve convective heat transmission while reducing pressure loss, the research used a rectangle wing pair (RWP) LVG installed on the fin. Using the ANSYS FLUENT is used to get the numerical outcomes. The top and lower plates are subjected to constant heat flux, and the working fluid (air) is chosen to be laminar (600 Reynolds 1400). The energy conservation problem was solved using the finite volume and finite difference (FD) approaches. Wing angles of approach (25, 35, 45, and 55°) and RWP LVG height were changed to assess the LVG's effectiveness. When compared to the reference instance, the Nusselt number rises by 22.23% when a CFU integrated RWP LVG is used at an angle of approach and height of (45°, 1.25mm). Contour and streamline maps were used to illustrate the temperature distribution of both primary and secondary flows. [ABSTRACT FROM AUTHOR]

In the continuous improvement of electric vehicles driving range, a heat pump system with low-global warming potential (GWP) refrigerant is a promising solution. In the present work, the condensation heat transfer coefficient (HTC) and frictional pressure drop (FPD) were experimentally evaluated in an offset strip fins embedded plate heat exchanger (PHE), using an eco-friendly, low-GWP refrigerant R290 as the working fluid. A Modified Wilson Plot Method was used to predict the heat transfer of the coolant side (water/ethylene glycol; 50/50 %). The main focus of the present study revolves around the R290-to-coolant condensation experiment, wherein we analyzed the influence of mass flux (G = 20–50 kg m−2 s−1), heat flux (q = 3–12 kW m−2), and saturation temperature (T sat = 40–55 °C) on HTC and FPD within the PHE while variable mean vapor quality (x m). According to the results, all experimental conditions were fall in the forced-convection condensation regime. The results state that HTC increases with a rise in q, G, and x m , but decreases with a surge in T sat. Conversely, FPD increases with a rise in G and x m , and decreases with a escalation in T sat , while q has no significant impact. Correlations were developed to predict the Nusselt number and friction factor values of R290 with mean absolute errors of 10.6 % and 11.2 %, respectively. These correlations are compared to previous research findings, signifying their efficacy in predicting the heat transfer characteristics of R290 within PHEs. • Condensation heat transfer performance of R290 was examined in PHE with OSF. • Flow regime of R290 was in forced-convective condensation for working conditions. • HTC increases with an increase in q and G but decreases with increase in T sat. • FPD was influenced by the range of G and T sat, but for q it remains unaffected. • Correlations for Nu and ff of R290 have 96.11 % and 94.21 % values under ±30 %. [ABSTRACT FROM AUTHOR]

Energy recovery in conventional thermal systems like power plants, refrigeration systems, and air conditioning systems has enhanced their thermodynamic and economic performance. In this regard, compact heat exchangers are the most employed for gas to gas energy recovery because of their better thermal performance. This paper presents an economic optimization of a crossflow plate-fin heat exchanger with offset strip fins. A detailed software-based numerical code for thermal, hydraulic, economic, and exergy analysis is developed for three fin geometries. Genetic Algorithm, parametric, and normalized sensitivity analyses are used to discover the most influential parameters to optimize the total cost. The parametric study showed that with the increase of mass flow rates and plate spacing, outlet stream cost and operating cost increased due to the rise in pressure drops. Finally, the optimization reduced the operational cost by ∼78.5%, stream cost by ∼64.5%, and total cost by ∼76.8%.

Downward condensation of a near-azeotropic low GWP refrigerant mixture of R290/R1270 (65%/35% wt.), named HC01, was investigated inside an offset strip-fin (OSF) flow-structured plate heat exchanger (PHE). This study tested the prototype heat exchanger with HC01 and compared the condensation heat transfer coefficient (CHTC) and pressure drop (CPD) with the pure R-290 for working conditions of refrigerant mass flux (G) = 20–50 kg/m2s, inlet vapor quality (x in) = 0.2–0.9, saturation temperature (T sat) = 40–55 °C, and heat flux (q) = 4–13 kW/m2. It was observed that the condensation of HC01 occurred entirely within the forced convection condensation flow regime, despite a slight change in the CHTC at a lower x in as the G increased. The CHTC demonstrated an increase in response to higher values of G and q, but decreased with increasing T sat. Similarly, the CPD exhibited an increase with higher G and a decrease with lower T sat , whereas the q had minimal influence. Comparison results showed that the HC01 exhibited 14.2% higher average CHTC but 6.5% lower CPD than that of R-290 because of the differences in properties, such as liquid thermal conductivity, viscosity, surface tension, latent heat, and discrepancies in liquid and vapor phase densities. Correlations were generated to predict the values of the Nusselt number (Nu) and friction factor (FF) of HC01, with mean absolute errors of 12.1% and 12.7%, respectively. • Comparative condensation analysis of R290/R1270 and R-290 were examined in heat exchanger. • Flow regime of R290/R1270 was in forced convective condensation. • CHTC of R290/R1270 increase with increase of RMF and TF but decreased with ST. • Average CHTC and CPD of R290/R1270 was 14.2% higher and 6.5% lower than R290. • Correlations for Nu and FF of R290/R1270 are developed with AAE of 12.1% and 12.7%. [ABSTRACT FROM AUTHOR]

• Two identical indirect solar dryers with and without offset strip fins (OSF) collector are constructed and simultaneously tested. • A peak temperature difference of 11.3 °C at the outlet of the collector in favor of OSF. • 43.22% of drying time saved using the suggested design. • Integrating offset strip fins in the solar collector is beneficial for drying applications. In the present study, two indirect type solar dryers were designed, fabricated and experimentally investigated, one is equipped with a conventional flat plate collector, and the other is integrated with offset strip fins (OSF). The objective is to study the effect of OSF on the performance of the dryer. A series of experimental tests were conducted at the applied research unit in the semi-arid region of Ghardaia using locally available materials. The first test was starting the solar dryers with an empty chamber and the second with filled product. The peak and average temperature difference at the outlet of the collector were 11.3 and 8 °C respectively, in favor of OSF absorber. The courgette was dried to 0.69 (kg water/kg dry basis) from an initial moisture content of 26.24 (kg water/kg dry basis) in 20 h 18 min and 35 h 45 min in the solar dryer with OSF and without, respectively. The results show a high drying rate using the dryer with OSF compared the dryer with conventional collector. Also, Midilli-Kucuk model provided the best agreements between experimental and predicted moisture ratios. Average effective moisture diffusivity of 1.798x10−09 and 1.179x10−09 m2/s for the dryer with OSF and without, respectively. A 33 % increase in economic efficiency in favor the OSF dryer with 0.95 years payback period. Also, a reduced amount of GHGs makes the dryers environmental friendly. [ABSTRACT FROM AUTHOR]

The primary aim of this study was to consider novel configurations of water-cooled micro-channel layout and compare them with existing configurations. The authors emphasize on establishing a benchmark based on investigations by earlier researchers and numerically analysing them. As a first attempt, offset strip fins are compared with existing parallel fins in terms of subsequent flow fields and temperature profiles. In offset types designated as A and B, the highest velocities occur at the side channels because of the straight wall allowing smooth flow through the channel. Generally, for offset type, the velocity increases after the sidewalls towards the centre. Type A configuration had an uneven velocity profile because of its staggered channel entrance. The lowest average temperature was observed in parallel heat sinks, followed by type A and type B. Causes are discussed for the observed differences and criteria are suggested for the selection of an appropriate geometry of offset fins. An efficient cooling system will ensure effective working of equipment resulting in low energy consumption and better sustainability. This work opens a platform for research on various other configurations and their use in micro-channel cooling. [ABSTRACT FROM AUTHOR]

This paper presents the experimental analysis of aluminum BPHX, with dimensions of 215 × 80 × 61 mm, having transversal offset strip fins with two pitches of 5 and 6.8 mm using liquid to liquid to measure the heat transfer and pressure drop performance in the Reynolds range of transitional to turbulent regime [103, 104]. Firstly, the heat exchangers were tested using water on both sides. A heat transfer and friction coefficients empirical correlations were determined, and the resulted functions were compared with two other models presented in the literature. Secondly, the heat exchangers were measured using water and engine oil as hot fluid. [ABSTRACT FROM AUTHOR]

This paper numerically explores the heat transfer behaviors of cryogenic fluids in offset strip fin (OSF) channels considering the important effect of fin efficiency that combines the factors of low thermal conductivity of fin material at cryogenic temperatures and the fin geometry. A series of numerical simulations, which involve three kinds of fin materials with different thermal conductivities and the cryogenic fluids including both gases and liquids of nitrogen, normal hydrogen and classic helium 4, are carried out with well-validated 3D models. The results show that lower thermal conductivity of solid material at cryogenic temperature causes a considerable reduction in heat transfer performance of OSF fins especially for the liquids with high Prandtl number. Further analysis of the results reveals that for different cryogenic fluids, Nusselt number is strongly related to Prandtl number and fin efficiency. In particular, Nusselt number is proportional to the Pr 0.235 η f 0.9 in laminar region, regardless of Reynolds number and fin geometries. The results for different fin geometries suggest that larger fin thickness-to-length ratio can help to improve the heat transfer performance, while smaller fin thickness-to-height ratio and higher fin density no longer contribute to higher j factor (or Nusselt number) of OSF fin, especially in the case of lower thermal conductivity of fin material. There exist optimum fin thickness-to-height ratio and fin density that correspond to the maximum value of j factor for the cryogenic fluids. [ABSTRACT FROM AUTHOR]

• Saturated flow boiling H tc and PD f of R290 investigated in a BHEX with OSF. • Effect of T s = 5–20 °C, G =20–60 kg m−2 s−1, q = 7.5–15 kW m−2, and X in = 0.1–0.8 were explained. • At higher X m , the boiling process was dominated by convection flow regime. • H tc of R290 strongly depends on X m and T s compared to G and q. • Proposed correlation for Nu and ff p of R290 have 89.7 and 90% values under ±30%. An inclusive experimental study was conducted to explore the saturated flow boiling heat transfer coefficient (HTC) and frictional pressure drop (PD f) features of R290 in a brazed plate heat exchanger embedded with offset strip fins with an offset length of 2 mm, fin thickness of 0.3 mm, and fin height of 2 mm. The experiment was conducted at four different saturation temperatures (T s = 5–20 °C), three mass fluxes (G =20–60 kg m−2 s−1), four heat fluxes (q = 7.5–15 kW m−2), and eight mean vapor qualities (X m) at increasing inlet vapor quality (0.1–0.8). The findings revealed that nucleate boiling vanquished at lower X m values, irrespective of the working conditions, despite the fact that at higher X m , the boiling process was dominated by convection. There was a dry-out condition inside the heat exchanger at X m = 0.42–0.63, except when G = 60 kg m−2 s−1. The result suggested that the HTC of R290 strongly depended on X m and T s compared with G and q. The PD f of R290 shows a strong dependence on T s , G , and X m , whereas it is less dependent on q. Moreover, PD f increases with an increase in G, X m , and q values, and decreases with an increase in T s. Furthermore, empirical correlations for Nusselt number and friction factor, which were developed for R290, accounted for the influence of equivalent and liquid Reynolds numbers and the liquid and vapor densities with a mean absolute error of 10% and 14%, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

Nowadays, computer simulations are becoming more and more important in performance investigation of thermal systems. In this article, radiator from a cooling system of a diesel engine of ER24PC locomotive is simulated. The radiator is composed of parallel and series arrangement of compact heat exchangers with offset strip fins. It also has two high and low temperature sections. Due to the complexity and compactness of heat transfer plates implemented in the radiator, the simulation is carried out in two steps. First, a relation for coolant-side and air-side heat transfer coefficient is correlated using computational fluid dynamics. Due to vortex shedding phenomenon in the staggered fin arrays, governing equations are solved transiently in twodimensional space. Appropriate timestep for the transient solution is chosen according to time period of vortex shedding from the surface. In the second step, using the developed computational code, the overall thermal performance of the radiator is simulated as a heat exchanger. Consequently, temperature distribution inside the radiator and its thermal performance are studied. Amount of heat released from the radiator in different flow rates and temperatures of fluid flowing out of the radiator are among the outputs of the developed code. Finally, thermal performance curve of radiator is obtained. [ABSTRACT FROM AUTHOR]

The heat transfer and flow friction coefficients for offset strip fins (OSF) used in plate-fin heat exchangers are numerically investigated with well validated 3D models. The effect of the geometrical three-dimensionality is analyzed in a distinctive way to understand the general behavior of the thermal hydraulic performance. Based on the analysis of a large amount of numerical data by CFD techniques for OSF fins, a couple of new correlations for general prediction of the j and f factors are developed, which excellently correlate a variety of geometrical parameters with blockage ratio ranging from 10% to 60%. Moreover, 252 experimental data-points for j and 290 experimental data-points for f covering 24 OSF fins are collected from literatures to examine the predicting abilities of the proposed correlations. The comparisons show that the proposed correlations can present the basic behavior of experimental data with nice accuracy. Further comparisons with the previous correlations from literatures have been done with regards to the same experimental data, which reflect that the proposed ones provide well-adapted predictions for OSF fins with different fin thickness covering a broad range of blockage ratio, while the previous correlations express growing prediction deviations as the blockage ratio increases. On the whole, the proposed correlation predicts 92.5% of the j data and 90.3% of the f data within 20%, with the RMS errors of less than 15%. The present work might be very helpful to guide the optimum design of plate-fin heat exchangers and also evaluate the performance of heat transfer enhancement in the OSF fin channels. [ABSTRACT FROM AUTHOR]

Abstract: Ice slurry is a promising alternative to conventional single-phase coolants in indirect refrigeration systems. In this paper, an experimental analysis of an offset strip-fin heat exchanger operating with ice slurry as working fluid is presented. The pressure drop and thermal performance have been determined. In order to obtain the partial thermal resistance in the ice slurry side an empirical correlation for the secondary fluid side was determined by applying the Wilson plot method in a set of tests performed previously. An empirical correlation in terms of the Colburn j-factor to describe the thermal behavior of the heat exchanger with ice slurry was obtained. On the other hand, the direct pressure drop measurements operating with different flow rates and ice fractions are shown and compared with values obtained with single-phase fluids. Pressure drop instabilities have been observed for flow rates lower than the nominal value provided by the manufacturer. [Copyright &y& Elsevier]

Abstract: Uniform distribution of fluids is crucial to obtain high performance in compact heat exchangers. Maldistribution has been studied by many authors, especially for parallel channels heat exchangers. But theoretical models and experimental studies for predicting flow maldistribution in offset strip fins exchangers are scarce. Offset strip fins, besides their higher thermal hydraulic performances, favour lateral distribution due to their geometry. In this work, an experimental investigation has been carried out for this type of heat exchanger. The experimental set-up consists in a flat vertical compact heat exchanger (1m×1m area and 7.13mm thickness) equipped with offset strip fins with a hydraulic diameter of 1.397mm. Air and water are the working fluids. The flow rates of each phase in seven zones regularly distributed at the outlet have been measured as well as the pressures at the inlet, the outlet and two intermediate positions. These measurements were completed with visualisations using a high-speed camera. First, the single-phase flow has been investigated. A correlation for friction factor has been derived from experiments covering laminar, transition and turbulent regimes. CFD simulations of the single-phase flow have been performed. The numerical results were compared with the determined correlation and with correlations available in the literature. In single-phase flow, a uniform distribution was experimentally observed. Then, the two-phase hydrodynamics was characterised. A flow regime map was established and the influences of phases inlet directions (co-current and counter-current inlets of the phases) and of superficial velocities on the distribution were studied. The gas superficial velocity has more effect on the distribution than the liquid one. Comparison between pressure drop profiles and flow rate distribution profiles shows that information about pressure drop can provide information about phase distribution. It must be noticed that the nonuniform distribution of phases can entail the coexistence of several flow regimes in the heat exchanger. [Copyright &y& Elsevier]

Abstract: Thermo-hydraulic design of compact heat exchangers (CHEs) is strongly dependent upon the predicted/measured dimensionless performance (Colburn factor j and Fanning friction factor f vs. Reynolds number Re) of heat transfer surfaces. Also, air (gas) flow maldistribution in the headers, caused by the orientation of inlet and outlet nozzles in the heat exchanger, affects the exchanger performance. Three typical compact plate-fin heat exchangers have been analyzed using Fluent software for quantification of flow maldistribution effects with ideal and real cases. The headers have modified by providing suitable baffle plates for improvement in flow distribution. Three offset strip fin and 16 wavy fin geometries used in the compact plate-fin heat exchangers have also been analyzed numerically. The j and f vs. Re design data are generated using CFD analysis only for turbulent flow region. For the validation of the numerical analysis conducted in the present study, a rectangular fin geometry having same dimensions as that of the wavy fin has been analyzed. The results of the wavy fin have been compared with the analytical results of a rectangular fin and found good agreement. Similarly, the numerical results of offset strip fin are compared with the correlations available in the open literature and found good agreement with most of the earlier findings. [Copyright &y& Elsevier]

Abstract: A steady-state three-dimensional numerical model was used to study the heat transfer and pressure drop characteristics of an offset strip fin heat exchanger. Water was the heat transfer medium, and the Reynolds number Redh ranged from 10 to 3500. Variations in the Fanning friction factor f and the Colburn heat transfer factor j relative to Redh were observed. General correlations for the f and j factors were derived, and these could be used to analyze fluid flow and heat transfer characteristics of offset strip fins in the laminar, transition, and turbulent regions. Finally, three performance criteria (j/f, j/f 1/3, and JF) were adopted, and the best performance criteria for the cases Pr=7 and Pr=50 were chosen to be JF and j/f 1/3, respectively. [Copyright &y& Elsevier]

Abstract: Compact heat exchangers are well-known for their ability to transfer large amounts of heat while retaining low volume and weight. This paper studies the use of this device as a chemical reactor, generally called a heat exchanger reactor (HEX reactor). Indeed, the question arises: can these geometries combine heat transfer and mixing in the same device? Such a technology would offer many advantages, such as better reaction control (through the thermal aspect), improved selectivity (through intensified mixing, more isothermal operation and shorter residence time, and sharper residence-time distribution), byproduct reduction, and enhanced safety. Several geometries of compact heat exchanger based on turbulence generation are available. This paper focuses on two types: offset strip fins (OSFs) and metallic foams. Our main objective is to contribute to the estimation of micromixing generated by these geometries by using an experimental method based on a unique parallel-competing reaction scheme proposed by Villermaux et al. The micromixing time, estimated according to the incorporation model, lets us compare the micromixing levels generated by duct channel, OSFs and metallic foams at volume flow rates ranging from 1 to 350lh−1. The metallic foam concept is found to be very efficient in micromixing enhancement. Furthermore, OSFs make it possible to generate micromixing levels ranging between the duct channel and metallic foam level. Moreover, the results show that the fin micromixing level increases with fin thickness and ligament diameter. Finally, in an HEX reactor application, the residence time of chemical reactants must be considered in order to choose the best geometry for intensifying mass and heat transfer. [Copyright &y& Elsevier]

Abstract: This paper presents an experimental study which demonstrates the potentiality of multifunctional heat exchangers (MHE) to carry out exothermal chemical reactions by the local control of the reactive environment temperature. Two highly exothermal chemical reactions with different kinetics (instantaneous and fast) have been investigated. The MHE is found to be very efficient in extracting the heat released by the chemical reactions. Due to its large heat transfer capacity, this process allows to increase considerably inlet reactant concentrations without thermal runaway and thus to enhance both chemical reaction conversion ratio and yield. This study also shows the limitations of the multifunctional heat exchanger for exothermal and instantaneous chemical reactions. [Copyright &y& Elsevier]

Abstract: An experimental study on saturated flow boiling heat transfer of R113 was performed in a vertical rectangular channel with offset strip fins. Two-phase pressure gradients and boiling heat transfer coefficients in an electrically heated test section were measured for the quality range of 0–0.6, mass flux range of 17–43kg/m2 s and heat flux of 500–3000W/m2. Two-phase frictional multiplier was determined as a function of Martinelli parameter. The two-phase forced convective component of the local boiling heat transfer coefficient was found to be well correlated with the Reynolds number factor. A superposition method for the flow boiling heat transfer coefficient that included the contribution of saturated nucleate boiling was verified also for flow boiling in a channel with offset strip fins. The predictions of local flow boiling heat transfer coefficients were found to be in good agreement with experimental data. [Copyright &y& Elsevier]

Counter-current two-phase flows of air-water in narrow rectangular channels with offset-strip fins have been experimentally investigated in a 760 mm long and 100 mm wide test section with 3.0 and 5.0 mm gap widths. The two-phase flow regime, channel-average void fractions and two-phase pressure gradients were studied. Flow regime transition occurred at lower superficial velocities of air than in the channels without fins. In the bubbly and slug flow regimes, elongated bubbles rose along the subchannel formed by fins without lateral movement. The critical void fraction for the bubbly-to-slug transition was about 0.14 for the 3 mm gap channel and 0.2 for the 5 mm gap channel, respectively. Channel-average void fractions in the channels with fins were almost the same as those in the channels without fins. Void fractions increased as the gap width increased, especially at high superficial velocity of air. The presence of fins enhanced the two-phase distribution parameter significantly in the slug How, where the effect of gap width was almost negligible. Superficial velocity of air dominated the two-phase pressure gradients. Liquid superficial velocity and channel gap width has only a minor effect on the pressure gradients. [ABSTRACT FROM AUTHOR]

• Multi-objective genetic algorithm and CFD were used to optimize heat exchanger fin shapes. • The resulting organic design has up to 89% performance improvement. • Genetic algorithm sensitivity to change in its parameters was investigated. • Effect of reynolds number on genetic algorithm performance was analyzed. Topology Optimization (TO) in the design of structural components is commonly used and well explored. However, its utilization in the design of complex thermo-fluid equipment used in aerospace applications is limited and relatively new. This is because the coupling between the fluid dynamics, heat transfer, and the shape is complex and nonlinear. Furthermore, the resulting geometry from a TO analysis is often very complex and difficult to manufacture due to the free forms that can occur. With the advent of Additive Manufacturing (AM), however, it has become possible to directly manufacture complex geometries. This study develops a new Genetic Algorithm (GA) based TO combined with Computational Fluid Dynamics (CFD) to produce optimized fin shapes for heat exchangers used in aerospace applications. To implement this approach, a rectangular shaped baseline fin geometry was created using voxel representation. An initial population is generated by mutating the baseline fin a random number of times. The CFD package OpenFOAM is then used to evaluate the performance of each design, after which the optimization algorithm is applied. The GA sorts the designs using a composite fitness function that is comprised of the overall heat transfer and pressure drop, and generates new generations based on mutation and carryover of top performing designs. The study also explores the sensitivity of the GA to the various GA parameters as well as the effect of varying flow Reynolds number. In general, as Reynolds number increases, the percent improvement in the optimum relative to the baseline increases, with potentially an 89% performance improvement. Overall, the approach enables generation of novel freeform designs that may open new performance space for heat transfer applications. [ABSTRACT FROM AUTHOR]

The plate-fin heat exchangers with pressure-resistant offset strip fins are widely used in the C3MR and other liquid natural gas (LNG) systems, and the two-phase pressure drop characteristics of flow boiling in pressure-resistant offset strip fin channels is a crucial factor for designing and optimizing the compact heat exchangers. A cryogenic experimental rig was established to obtain two-phase pressure drop data in the present study and the fin thickness of 0.4 mm is selected based on an actual compact heat exchanger in the C3MR LNG liquefaction system. The tested fluid is R22, and the experimental conditions include mass fluxes of 64–128 kg/(m2·s), vapor qualities of 0.1–1.0, saturation pressures of 0.22–0.26 MPa, and heat fluxes of 0.7–5.5 kW/m2. The comparison between the obtained data for fin thickness of 0.4 mm and those for fin thickness of 0.1–0.4 mm in literatures show that, the friction factor f of gas flow in channels increases with the increasing fin thickness, and the increment is 306%–451% as the fin thickness increases from 0.1 mm to 0.4 mm. The research results of two-phase flow show that, as the vapor quality increases, the frictional pressure drops initially increase and then decrease, representing a maximum at vapor quality of 0.90. With the increment of heat fluxes, the average vapor quality increases, resulting in the increasing frictional pressure drops. The two-phase multiplier of two-phase pressure drop varies from 3 to 35 and increases with the decreasing fin thickness and hydraulic diameter. A new correlation of two-phase pressure drops in offset strip fins with different fin thicknesses was developed within a deviation of ±25%. • New experimental data for cryogenic compact heat exchanger are obtained. • Friction factors of pressure-resistant offset strip fins are correlated. • Effects of mass fluxes, heat fluxes on two-phase pressure drop are analyzed. • Structural parameters were introduced into new developed correlations. [ABSTRACT FROM AUTHOR]