Cold Flow Research Articles

Design and optimization of molten salt printed circuit steam generators

Among the array of heat exchangers available, printed circuit steam generators emerge as a particularly promising choice for high-temperature applications. This is primarily attributed to their augmented heat transfer surface area, which enables the efficient transfer of thermal energy within the Rankine power conversion cycle, especially in the context of molten salt-based thermal power systems, such as those employed in molten salt reactors and concentrated solar power plants. It is imperative to analytically model the heat transfer characteristics of mini-channel flow boilings for a printed circuit steam generator. To resolve new technical design issues that the single hot fluid flow channel is cooled by multiple cold fluid flow channels, an improved heat exchanger model is proposed to assist the numerical modeling of printed circuit steam generators for molten salt based on the equilibrium thermodynamics quality of water/steam flow. The existing flow boiling heat transfer coefficient correlations of mini-channels are leveraged to optimally design the straight-passage based printed circuit layouts and narrow down their optimal operational parameters. With various selections of subcooled water, saturated water, and superheated steam heat transfer correlations, The best combination of heat transfer correlations is found to assess the axial distributions of cold fluid temperatures and pressure drops. Two multi-objective optimizations are formulated to respectively solve thermal sizing and scaling problems for the optimal designs and operations of printed circuit steam generators. The computational results indicate that the overall heat transfer coefficient for an optimized 50 MW(th) printed circuit steam generator assessed at the transition point is about 3,828 W/(m2 K), which remarkably surpasses the 1,544 W/(m2 K) value of the conventional shell-tube steam generators by a factor of three. This implies that printed circuit steam generators would be a promising replacement of the traditional shell-tube steam generator.

Experimental investigation of pressure drop and heat transfer in minichannel with smooth and pin fin surfaces

This study investigates pressure drop and heat transfer characteristics in a minichannel heat exchanger experimentally. The experimental testing was carried out on a minichannel with a hydraulic diameter of about 2.5 mm, with smooth and embedded with circular pin-fins. The testing was conducted with different hot fluids, air and water, over different Reynolds numbers ranges, and over different heat capacity ratios (0.25, 0.5, 0.75, and 1). The experimental study of the pressure drop covers a Reynolds number range between 100-1900 for the hot water, and Reynolds number range between 500-10,000 for the hot air. The hot fluid flows through a channel with an inline arrangement with a 1750 pin fin, while the cold fluid flows through a smooth channel. Increasing flow rates resulted in an increase in pressure drop and heat transfer coefficients. When using pin-fins surface instead of smooth surface, the overall heat transfer coefficient (U) increased by 190% when water is used as the heat transfer fluid (HTF), and the same coefficient increased by 42% when air is used as the heat transfer fluid. Similarly, the difference in pressure drop is low in the case of water-water, while in the case of air-water, the difference in pressure drop is more substantial as Reynolds number increases.

An NEA/OECD benchmark-experiment for the validation of CFD for mixing and thermal fatigue in T-junction dead leg flows

The current screening criteria for thermal fatigue used in isolated branch lines at nuclear power plants are based on simplified approaches, which, on one hand, tend to be overly conservative, and on the other hand, appear to miss important physics. This is demonstrated by the fact that a number of affected pipes were missed by the current screening methods.The purpose of the present work is to produce novel and accurate experimental data, which can be used for a benchmark of Computational Fluid Dynamics (CFD) in order to advance the prediction capabilities of thermal mixing and fatigue in dead leg T-junctions and improve the accuracy of the screening criteria. The ultimate value creation is increased safety and availability at nuclear power plants. This is of great interest and utmost importance to the nuclear reactor safety community.A new pressurized experimental setup of a T-junction has been designed and constructed for the purpose. The experimental setup, with a temperature difference of 120 °C, more closely resembles plant conditions than in earlier experiments. The boundary conditions in terms of the flowrates and temperatures are controlled and stable within their measurement uncertainty – a prerequisite for CFD-grade experiments.The novelty of the present work is measurements of the temperature fluctuations both in the near wall fluid mixing region and throughout the solid pipe wall material.It has been shown that the interaction between the swirl penetration of hot water and the stratified layer in the cold dead leg has an intermittent character and that random clusters of bursts of hot water penetrate into the stratification and the stagnant cold water below. The average time scale of this process is of the order of hundreds of seconds.The stratification between the hot and the cold water in the dead leg has also shown to have a low frequency oscillation of the order of 0.1 Hz, which wiggles in the circumferential direction. After hot water has penetrated downward and excited the instability, the temperature falls back to the initial one in a manner similar to a damped oscillation.The vertical temperature profiles have shown to be self-similar, for moderate temperatures, when scaled with the temperature difference between the hot and the cold water and with the penetration length.The penetration length increases with the velocity in the hot leg confirming earlier reported correlations.A small (less than 0.1 % of the hot main flow) cold leakage flow into the T-junction is sufficient to suppress the swirl penetration and substantially reduces the penetration length. However, the temperature fluctuations have a larger amplitude and range across the whole mixing zone. The fluid temperature fluctuations are shifted towards a more high frequency content, however, the low frequency nature of the swirl penetration is still present.The obtained novel dataset will be provided for a blind CFD benchmark exercise as part of an OECD/NEA project in 2023 and 2024.

Experimental investigation of the convective heat transfer coefficients at different angular orientations inside the void in a cold flow pebble bed reactor using a non-invasive heat transfer pebble probe

This study focuses on investigating the effect of the surface location of the pebble inside the bed, by varying the angular orientation of the heat transfer pebble probe and the velocity of the gas on the convective heat transfer coefficients in a cold-flow pebble bed reactor. An advanced non-invasive technique consisting of a cartridge heated copper pebble, a micro-foil sensor and a thermocouple probe was used to obtain accurate measurements of the local heat transfer coefficients from three surface locations inside the void. The effect of the wall on the local convective heat transfer coefficients was highlighted due to the low aspect ratio of the bed (bed diameter to pebble diameter (5cm)) used in this work. The local measurements showed, for the first time ever, that the surface location inside the void substantially impacts the heat transfer coefficients, with higher heat transfer coefficients at the center of the void and bottom of the void. Furthermore, the measured overall heat transfer coefficients showed good agreements with the predictions of the correlations of [52,21] and [14]. A second order polynomial model with an R2=0.9807 and an average absolute relative error (AARE) equal to 9.08%, was developed for the prediction of the local heat transfer coefficient within the design and operation conditions of this work. The accurate local heat transfer data collected in this work is valuable as benchmark data for the validation of computational fluid dynamics (CFD) simulations and heat transfer calculations.

Research on blending combustion characteristics of coaxial injector of oxygen/methane engine

Aiming at the demand of oxygen/methane rocket engine for future reusable spacecraft, the design of oxygen/methane coaxial injector engine and the study of flow mixing and combustion characteristics were carried out. The flow field characteristics, flame structure size and heat release state changes under different fuel-oxygen momentum ratio of coaxial injector were investigated. The results show that the increase of fuel-oxygen momentum ratio in the cold flow state increases the influence of the mainstream flow on the flow in the combustion chamber, and the length of the vorticity shear layer also increases. With the increase of fuel-oxygen momentum ratio, the flame's lifting distance gradually decreases, the rate of methane needed to stabilize the flame in the shear layer is over twice that of oxygen. At this time, as this ratio increases, the flame expansion angle increases while its length decreases. Rich combustion in the return zone is suppressed, but there is still some impact on component distribution ahead of main heat release. With the increase of fuel-oxygen momentum ratio, the starting position of the high temperature zone gradually advances, and the increase of fuel-oxygen momentum ratio makes the mainstream temperature change significantly intensified. Within a fuel-oxygen momentum ratio range of 0.5–2, the alteration of this ratio has a significant impact on the temperature profile of the gas close to the wall. However, as the ratio increases, the effect of this change on the gas temperature diminishes significantly.

Relationships between crystallization behavior and application properties of chemically coupled PAI-PTFE coatings

AbstractPoly(tetrafluoroethylene) (PTFE) is well known for its very low friction coefficient and thus widely used for antifriction applications, e.g., sliding lacquers, for many years. Because of the high wear rate and cold flow of the original polymer, PTFE is usually added in higher amounts to other polymer matrices as a lubricant. However, the incompatibility of PTFE requires lots of efforts to perform a homogeneous breaking down of agglomerates and particle distribution as well as dispersion stabilization of the physical mixtures during application and curing. PTFE can be functionalized by high energy irradiation and subsequently compatibilized with a polymer matrix by reactive extrusion resulting in chemical bonding of both polymers via suitable reactive groups. In this manner, poly(amide imide) (PAI) was coupled to γ-radiation modified PTFE micro-powder prior to the dispersion procedure. This study deals with the thermal and crystallization behavior of the PTFE lubricant in chemical bonded (cb) PAI-PTFEcb compound thin layers in comparison with those of the plain radiation modified PTFE depending on the cooling rate by DSC, Flash-DSC and WAXS. A morphological characterization of the extrudate as well as the coating gives information about the fragmentation and distribution of the PTFE phase in the PAI matrix. Furthermore, mechanical and surface properties of sliding lacquer films were analyzed after application on steel substrates by varying dry film thickness and curing. Graphical Abstract

Salvia farinacea seed oil, a potential biomass for synthesis of biodiesel: A critical analysis of its fuel properties.

The non-renewable energy sources such as coal, petrol decreasing day by day and their price also increasing. In this fast depleting era of fossil fuels biodiesel produced from nonedible seed oils plays an important role. In the present work the biodiesel is produced from nonedible seed oil Salvia farinacea. In this work from Salvia farinacea seeds oil is extracted and fatty acid components are analysed by GC-FID. Physicochemical properties of the oil are determined by AOAC standard methods. The oil is transesterified in presence of KOH catalyst. Fuel parameters like iodine number, cetane number, heating values, kinematic viscosity, flash point, cold flow properties are determined and are compared with already existing biodiesels and petrodiesel. The emission components like CO, CO­­2, NOx, HC and Smoke opacity are analysed using four stroke one cylinder engine. This work reveals that Salvia farinacea seed oil is a potential renewable feedstock for the production of biodiesel.

Comparing the Cold, Warm, and Hot Deformation Flow Behavior of Selective Laser‐Melted and Electron‐Beam‐Melted Ti–6Al–2Sn–4Zr–2Mo Alloy

The cold, warm, and hot deformation flow behavior and mechanical properties of the Ti‐6242 alloy produced by selective laser melting (SLM) and electron beam melting (EBM) are compared. Hot compression tests are conducted over a wide temperature range (100–1000 °C) at a constant strain rate of 0.001 s−1. The yield and overall strength levels of the SLMed specimens are higher than those of the EBMed specimens at all temperatures. A thermally stable region is observed for SLMed specimens in the temperature range of 100–700 °C, but the strength level drops significantly (approximately 300–500 MPa) at above 700 °C. The stability region shifts to the lower temperature range of 100–600°Cfor the EBMed specimens, and strength starts to decrease at 600 °C. Both specimens experience fracture in a cold‐temperature regime but exhibit a high strain tolerance of approximately 0.4. The SLMed samples display a completely brittle behavior at a warm temperature regime, whereas, the EBMed specimens demonstrate better formability, tolerating higher compressive strains. The softening fraction substantially increases at high temperatures, indicating safe domains for thermomechanical processing of additively manufactured Ti6242 alloy.

Cooling and anti-friction effects of vortex tube cryogenic minimum quantity lubrication in milling of 3D printed iron-nickel alloy

3D printed iron-nickel alloy is a promising engineering material with superior properties, which is widely applied in aerospace, nuclear and petrochemical industries. However, it is rather a difficult-to-cut material due to the insufficient cooling and lubrication, and the cost of tool usage is extremely high even with TiAlN coated or TiCN coated tools. Although some scholars have attempted to conduct the eco-friendly VT-cMQL (Vortex Tube-cryogenic Minimum Quantity Lubrication) system for machining iron-nickel alloy, this outdated VT-cMQL in Parallel mode still has huge shortcomings in terms of lubrication and anti-friction effects, energy consumption, and minimum hardware requirements. To solve this problem, this work proposed a new series VT-cMQL system in forms of Tandem I and Tandem II. The results show that the structure of new VT-cMQL system in Tandem I mode is simple, that only requires 1 air filter, 1 air compressor, 2 sections of pipe, and no T-joint is needed. The lowest cold flow temperature is −4.7 °C when the spray pressure, spraying distance, pipe length, and oil supply are 1.5 bar, 10 mm, 30 cm, and 45 ml/h, respectively. The cooling and anti-friction effect of VT-cMQL has little impact on milling tool's adhesion or oxidation, the main contribution is to further reduce abrasive wear. From the perspective of iron-nickel alloy industrial production, the new proposed VT-cMQL system can significantly reduce hardware configuration and improve the utilization of cryogenic compressed air.

RATIONAL CONTROL BY TEMPERATURE IN VORTEX ENERGY SEPARATOR UNDER DESTABILIZING EFFECTS

The focus of this study is the arrangement of a rational control technique used to maintain the airflow temperature in a vortex energy separator (VES) under destabilizing effects. The objectives include the development of tools for the rational control of temperature in the cold and hot air flows of a VES. Methods used: Discrete state space, production rule statement, resolution of two-valued predicate equations, dichotomous trees, diagnosis, and recovery of dynamic objects. Problems settled: the studied features of the vortex energy separation process, architecture, and operation links of the rational control system were considered, mathematical models were deduced, and tools for diagnosing and recovering the efficiency of the vortex energy separator as a rational control object were developed. The scientific novelty of the study lies in the formation of instrumental tools to provide rational control of the airflow condition in the VES, where the control object is subjected to the substantial influence of various destabilizing effects.

Evaluation of a high oleic soybean oil variety in lubricant and biodiesel applications

AbstractSoybean oil is an abundant commodity crop that has garnered attention for its use as a feedstock for sustainable materials. Soybean oil is high in polyunsaturated fatty acid content, which can promote undesirable properties in biodiesel and lubricant applications. In this work, we characterized the fatty acid composition of commercial soybean oil along with two other soybean oil varieties, Ellis and TN18‐4110. Ellis and commercial soybean oils had similar fatty acid compositions, while TN18‐4110 was enriched in the monounsaturated oleic acid. Biodiesel and estolides were prepared from the three varieties and the relevant physical properties were measured. In comparison to commercial soybean diesel, both Ellis and TN18‐4110 exhibited unique advantages. As estolide‐based lubricants, all three varieties had advantageous cold flow properties, but TN18‐4110 also possessed excellent oxidative stability and lower viscosity. The physical properties and structural property relationships of the biodiesel and estolides are discussed.

Experimental evaluation on pre-swirling cold air for flue cooling

The operation of a diesel engine leads to the emission of a substantial amount of waste heat flue gas, resulting in a continuous increase in the wall temperature of the exhaust system. To mitigate this continuous rise in temperature, a pre-swirling device has been developed to enhance the heat exchange between cold air and the wall, thus averting heating wall by the hot air. In this study, an experimental system was devised and implemented to analyze the dynamic behavior of the wall temperature in an air duct. The system considered both with and without the pre-swirling device, incorporating different cold air temperatures and flow rates to examine its impact on the increase in wall temperature. The results revealed a gradual rise in wall temperature after reaching a steady state, particularly demonstrating lower wall temperatures at 19 measurement points in the presence of pre-swirl compared to without swirl. Notably, the maximum temperature rise in the air duct wall was reduced by 55.7 %, from 7.9 °C without pre-swirl to 3.5 °C with the inclusion of the pre-swirling device, highlighting the significant thermal protection it provides and suggesting potential applications in exhaust thermal protection engineering. Moreover, the experimental findings consistently indicate that the incorporation of a pre-swirling device effectively diminishes the increase in wall temperature across different cold air flow rates and temperatures.

Operational envelope for planning cold flow production

The paper presents a method to determine an operational envelope for the cold flow technology with respect to producing gas–oil ratio (GOR) and water cut (WC). The cold flow technology is a flow assurance method that enables cold production flow in thermal equilibrium with the seabed temperature. Cold flow converts hydrate and wax into dry, non-plugging microparticles inside a subsea cold flow unit downstream the wellhead. The small particles travel along with the liquid in the form of a slurry to the receiving host. The operational envelope shows that if the production flow reaches certain combinations of GOR and Wc, the hydrate volume fraction in liquid and consequently the slurry’s effective viscosity could be too high for pipe transportation. This paper also investigates the case when the slurry is transported with remaining water, where there might be some emulsion phenomena. Results show that this could reduce the operational region of the cold flow envelope, particularly for GOR–Wc values around the inversion point volume fraction. Therefore, water–slurry emulsification should also be taken into consideration when considering the operational envelope. If the hydrate–oil mixture is found to be too viscous to transport it can be resolved by, for example, removing water from the production flow upstream the cold flow unit. GOR–WC profiles from a real field case are over-imposed on the operational envelope to see the development during the field lifetime. Tieback costs for the cold flow technology are found to be 20–30% less than conventional methods for a 100 km tieback. The relative cost reduction increases with increasing tieback distance.

Improved steam utilisation with internals in the reactor section of fluid cokers

Gas tracer experiments were carried out in a cold flow model that is geometrically and dynamically scaled down from commercial fluid cokers at a one ninth scale. Continuous helium tracer injections were made into the attrition and stripping gas spargers to observe the gas-solids mixing in the dense bed. Helium concentration profiles, which represent steam in the commercial reactor, were measured with different baffle configurations. The experiments demonstrate the annular region of the dense bed was helium-lean without any internals, meaning stripping is poor at the vessel walls, whereas the addition of internals promotes dense bed stripping in the proximity of the internal. Improved steam distribution implies better stripping performance, which leads to increased reactor product yield.

Influence of the turbulence model on the numerical predictions of cold turbulent flow in a heavy-duty gas turbine DLN combustor

The influence of different turbulence models on the numerical predictions of cold turbulent flow in a 300 MW F-class DLN combustor was investigated in this study. PIV and PLIF test data were obtained and used for comparison. The simulation results obtained using the LES method exhibited a high level of agreement with the experimental results regarding the velocity distribution and recirculation zone scale. Of the RANS models, only the results from the RNG k-ε and Realizable k-ε are comparable to the experimental data and are suitable for rapid simulation of the combustor flow field. Conversely, the Standard k-ε, SST k-ω, and RSM model results display notable differences from the experiment. Regarding the mixing simulation in the combustor, the LES method was the closest to the experiment. The RANS models roughly reflect the same mixing trend as the experiment, despite the tracer gas diffusing much slower than in the experiment.

Heat Extraction in Geothermal Systems with Variable Thermo-Poroelastic Fracture Apertures

The fracture network largely determines the efficiency of heat extraction from fractured geothermal reservoirs. Fracture openings are influenced by thermo-poroelastic stresses during cold fluid flow, with the interplay between fracture length and fracture opening regulating heat transfer. The lack of field data concerning fluctuating fracture openings underscores the necessity for computational models. This work emphasizes the impact of such gaps in the literature. Factors such as temperature, pressure, stress, thermal breakthrough time, and cumulative energy are evaluated to analyze the system’s behavior. A sensitivity analysis is employed to ascertain the significance of stress on fracture opening, compared with thermo-hydraulic behavior. The results show that stress field alterations, due to intersections with minor fractures, can cause up to a 15% variation in the largest fracture’s opening. The impact of thermoelastic stress outweighs the impact of poroelastic stress approximately threefold. Such stress-induced variations in fracture openings can lead to an up to 30% increase in cumulative heat extraction, while the drop in production temperature is limited to around 50%.

Numerical investigation of the effect of strut geometries on the flow characteristics in a model combustor

PurposeThe mixing of fuel and air plays a pivotal role in enhancing combustion in supersonic regime. Proper mixing stabilizes the flame and prevents blow-off. Blow-off is due to the shorter residence time of fuel and air in the combustor, as the flow is in supersonic regime. The flame is initiated in the local subsonic region created using a flameholder within the supersonic combustor. This study aims to design an effective flameholder which increases the residence time of fuel in the combustor allowing proper combustion preventing blow-off and other instabilities.Design/methodology/approachThe geometry of the strut-based flameholder is altered in the present study to induce a streamwise motion of the fluid downstream of the strut. The streamwise motion of the fluid is initiated by the ramps and grooves of the strut geometry. The numerical simulations were carried out using ANSYS Fluent and are validated against the available experimental and numerical results of cold flow with hydrogen injection using plain strut as the flameholder. In the present study, numerical investigations are performed to analyse the effect on hydrogen injection in strut-based flameholders with ramps and converging grooves using Reynolds-averaged Navier–Stokes equation coupled with Menter’s shear stress transport k-ω turbulence model. The analysis is done to determine the effect of geometrical parameters and flow parameter on the flow structures near the base of the strut where thorough mixing takes place. The geometrical parameters under consideration include the ramp length, groove convergence angle, depth of the groove, groove compression angle and the Mach number. Two different strut configurations, namely, symmetric and asymmetric struts were also studied.FindingsHigher turbulence and complex flow structures are visible in asymmetric strut configuration which develops better mixing of hydrogen and air compared to symmetric strut configuration. The variation in the geometric parameters develop changes in the fluid motion downstream of the strut. The fluid passing through the converging grooves gets decelerated thereby reducing the Mach number by 20% near the base of the strut compared to the straight grooved strut. The shorter ramps are found to be more effective, as the pressure variation in lateral direction is carried along the strut walls downstream of the strut increasing the streamwise motion of the fluid. The decrease in the depth of the groove increases the recirculation zone downstream of the strut. Moreover, the increase in the groove compression angle also increases the turbulence near the base of the strut where the fuel is injected. Variation in the injection port location increases the mixing performance of the combustor by 25%. The turbulence of the fuel jet stream is considerably changed by the increase in the injection velocity. However, the change in the flow field properties within the flow domain is marginal. The increase in fuel mass flow rate brings about considerable change in the flow field inducing stronger shock structures.Originality/valueThe present study identifies the optimum geometry of the strut-based flameholder with ramps and converging grooves. The reaction flow modelling may be performed on the strut geometry incorporating the design features obtained in the present study.

Energy budget of cold and hot gas–solid fluidized beds through computational fluid dynamics-discrete element method simulations

Direct energy budget is carried out for both cold and hot flow in gas–solid fluidization systems. First, the energy paths are proposed from thermodynamic viewpoints. Energy consumption means total power input to the specific system, and it can be decomposed into energy retention and energy dissipation. Energy retention is the variation of accumulated mechanical energy in the system, and energy dissipation is the energy converted to heat by irreversible processes. Then based on the computational fluid dynamics-discrete element method framework, different energy terms are quantified from the specific flow elements of fluid cells and particles as well as their interactions with the wall. In order to clarify the energy budget, it is important to identify which system is studied: the particle-fluid system or the particle sub-system. For the cold flow, the total energy consumption of the particle sub-system can well indicate the onset of bubbling and turbulent, while the variation of local energy consumption terms can reflect the evolution of heterogeneous structures. For the hot flow, different heat transfer mechanisms are analyzed and the solver is modified to reproduce the experimental results. The impact of the heat transfer mechanisms and heat production on energy consumption is also investigated. The proposed budget method has proven to be energy-conservative and easy to conduct, and it is hopeful to be applied to other multiphase flow systems.

On the spatial characteristics of the flame transfer function for a GCH4-GO2 swirl coaxial flame

In this study, the combustion instability characteristics of gaseous methane–gaseous oxygen atmospheric flame were investigated. A swirl coaxial injector was used under external modulation with a central methane flow and a loudspeaker. The flame transfer function with a photomultiplier tube was examined for possible errors, and an injector transfer function was defined to study the influence of the input perturbation on the cold gas flow without combustion. Both the results of flame transfer function and injector transfer function were affected by acoustic resonance. However, a higher mode of resonance did not appear in the flame transfer function. To analyze this difference, the flame movement was visualized using a high-speed camera by capturing the OH* chemiluminescence signal. Furthermore, a local flame transfer function was defined to examine the flame response zone-by-zone through a light signal. A higher-mode reaction appeared again in the local flame transfer function. It was found that flame separation due to modulation was the cause of the difference among the flame transfer function, injector transfer function, and local flame transfer function. By capturing the entire flame, its periodicity could be lost; hence, the local flame transfer function could prevent misinterpretation of the flame fluctuation.

EVALUASI UNJUK KERJA ALAT PENUKAR KALOR JENIS CONCENTRIC DENGAN VARIASI KECEPATAN ALIRAN FLUIDA KERJA

Heat transfer is a science of heat transfer energy that is indispensable for analyzing the heat transfer process. One type of heat exchanger that is widely used is the Concentric heat exchanger. From the explanation of the theory that the influence of increasing the flow velocity of the cold fluid will affect the increase in the value of the performance of the heat exchanger. Therefore, this influence will provide an increase in heat transfer performance, especially at the heat transfer rate, (Q), heat transfer coefficient (U), and also heat transfer effectiveness (ε). By increasing the variation in the flow velocity of cold fluid by setting the temperature of the hot fluid (Thi) at 45°C and the temperature of the cold fluid (Tci) at 27°C and also made constant up to the highest velocity variation in the cold fluid. From the most minimum performance value at a cold fluid flow rate of 0.067 m/s to 0.134 m/s in the concentric heat exchanger type, performance values were obtained including the heat transfer rate (Q) from 714.09 Watts to 1111.51 Watts on the heat side and 619.89 Watts to 901.83 Watts on the cold side, for the heat transfer coefficient (U) a value of 337.90 W / m2 was obtained. C to 405.38 W/m2. C , and for the effectiveness (ε) which was originally 29% to 43%.