Heat Exchanger Research Articles

Smart Materials in Green Architecture: The Role of ETFE and Phase Change Materials in Sustainable Building Design

Given the importance of energy in achieving environmental sustainability in green buildings, one of the most significant solutions is to reduce physical building consumption and instead use renewable energy to prevent the depletion of natural resources and environmental pollution. Utilizing advanced technologies and intelligent systems in architecture is one of the methods that can achieve energy management in buildings and ensure comfortable conditions for the occupants of green buildings. In the field of future-oriented architecture, it is expected that in the future, materials and technologies developed over the past century will define the different challenges ahead to elevate sustainable development in the building industry. Using solar energy, one of the latest innovations in buildings, and other measures such as ETFE panels (a green roof idea with an intelligent system) and thermochromic materials, which change color to minimize heat exchange between interior and exterior spaces of the building, show that today's world faces energy crises. The use of smart materials tailored to environmental conditions can significantly impact building design and have beneficial effects in terms of compatibility with the environment, increased lifespan of materials, and the adaptability of materials to changing weather conditions, thus aiding in achieving sustainable architecture. Therefore, this article aims to introduce intelligent materials and their applications and benefits in green building architecture based on library studies. The primary goal is to identify and highlight the most crucial aspects of using intelligent materials and their performance in buildings and how these materials behave and perform in architectural designs. The best way to leverage the benefits of these smart energy-saving materials and management for achieving sustainable architecture will be discussed.

Carbon sequestration by ecosystems of cold territories of Transbaikalia

In the Baikal region, the continuous cryolithozone occupies ≈15, the transitional intermittent zone with Talikov islands – 30, the transitional island zone – 45, taliki with a continuous area – 10%. Attention is drawn to the dominance of the transition band, which is characterized by unstable thermodynamic equilibrium. High-temperature permafrost is easily degraded by technoconversion of external heat exchange conditions: removal of ground covers (organogenic layer and snow cover), deforestation, plowing, fires, etc. These circumstances increase the natural hazards and risks in the region. In this regard, the territory of Transbaikalia is of great interest, being in the permafrost zone and near its southern border, on the one hand, and with increased warming rates in recent decades, on the other. The continentality and severity of the climate in Buryatia are much more pronounced than in neighboring single-latitude regions of Russia. The southern boundary of the cryolithozone stretches almost throughout the entire territory of the republic, within which a whole range of landscapes is distinguished – from automorphic forest ecosystems to widespread, due to the high proportion of lakes and swamps, hydromorphic landscapes formed under the active influence of permafrost, as well as dry-steppe. The implementation of the Kyoto Protocol on Stabilization of Greenhouse Gas (GHG) Concentrations in the Atmosphere requires a quantitative assessment of spatiotemporal changes in terrestrial carbon sinks. Identifying areas with high potential and strategies for managing sequestration of atmospheric carbon dioxide by ecosystems is an important task and there is great uncertainty about the actual estimates of carbon reservoirs and how they may be affected by climate change. In the current conditions, we consider the study of the patterns of functioning of the soil and plant carbon reservoir in Transbaikalia to be timely and relevant.

Numerical Simulations of Thermodynamic Processes in the Chamber of a Liquid Piston Compressor for Hydrogen Applications

This paper presents the results of numerical simulations examining the thermodynamic processes during hydraulic hydrogen compression, using COMSOL Multiphysics® 6.0. These simulations focus on the application of hydrogen compression systems, particularly in hydrogen refueling stations. The computational models employ the CFD and heat transfer modules, along with deforming mesh technology, to simulate gas compression and heat transfer dynamics. The superposition method was applied to simplify the analysis of hydrogen and liquid piston interactions within a stainless-steel chamber, accounting for heat exchange between the hydrogen, the oil (working fluid), and the cylinder walls. The study investigates the effects of varying compression stroke durations and initial hydrogen pressures, providing detailed insights into temperature distributions and energy consumption under different conditions. The results reveal that the upper region of the chamber experiences significant heating, highlighting the need for efficient cooling systems. Additionally, the simulations show that longer compression strokes reduce the power requirement for the liquid pump, offering potential for optimizing system design and reducing equipment costs. This study offers crucial data for enhancing the efficiency of hydraulic hydrogen compression systems, paving the way for improved energy consumption and thermal management in high-pressure applications.

Numerical simulation of heat transfer processes in shell and tube phase change heat exchangers for recovering industrial waste heat

Abstract This article combines phase change energy storage technology with shell and tube heat storage and exchange devices to establish a three-dimensional numerical model of the shell and tube phase change heat storage and exchange device. The hexahedral structured grid division is used to make the simulation results more accurate. Combined with the computational fluid dynamics software Fluent and the related principles of phase change heat transfer, the effects of different heat transfer fluid temperatures and flow rates on the phase change process of phase change materials and the fluid outlet temperature in the phase change heat exchanger were numerically simulated. The results show that under the set parameters, when the inlet water temperature increases from 70℃ to 90℃, the time required for the outlet temperature to increase from 20℃ to 60℃ is shortened by 23%, while when the temperature is constant, the inlet temperature of heat transfer fluid is shortened by 69%. Analysis shows that the influence of the inlet temperature of the heat transfer fluid on the heat storage and release of phase change materials is significantly greater than the inlet flow rate.

INVESTIGATION OF HEAT EXCHANGE PROCESSES IN A COOLING SYSTEM IN A POULTRY HOUSE WITH SIDE VENTILATION

A new method of cooling the outside air in the ventilation systems of poultry houses is proposed, based on the use of water from underground wells and heat exchangers for cooling the supply air. Numerical modeling of aerodynamics and heat transfer processes in poultry houses with a tunnel ventilation system was carried out. As a result of numerical calculations, the distribution of temperatures, velocities, and pressures in the air environment of the poultry house was obtained. The use of heat exchangers to cool the supply air makes it possible to maintain its temperature at +20-25 ℃ and reduce the moisture content in poultry houses, which is high when using cassette methods or spraying water with nozzles to cool the supply air. As a result of the numerical studies, it is recommended to increase air flow rates by including a third exhaust fan located on the top line of the rear end wall. This will allow for a more even temperature distribution in the house.

Six years of high-resolution monitoring data of 40 borehole heat exchangers

Ground-source heat pumps (GSHPs) coupled with borehole heat exchangers (BHEs) are energy-efficient technologies for heating and cooling buildings. However, these systems often fail to operate at their full potential due to discrepancies between the assumptions made during the design phase and the actual conditions during operation. To enhance overall GSHP performance, it is crucial to collect and analyze long-term monitoring data from operating BHE fields. To our knowledge, no long-term, high-resolution dataset of double U-tube BHEs is currently publicly available. Additionally, most studies typically monitor only the inlet and outlet of the entire ground heat exchanger rather than individual BHEs, hindering detailed performance analysis. With this data descriptor, we present a 6-year dataset from a BHE field comprising 40 BHEs, each with sensors for volume flow and inlet/outlet temperatures, recorded every 30 seconds. We believe this dataset will enhance understanding of individual BHE performance, provide validation for BHE models, and thus support better GSHP design and operation.

Strengthen of metal-polymer direct molding bonding via three-dimensional porous mechanical interlocking

This paper proposes a direct metal–polymer forming–bonding method using three-dimensional (3D) porous mechanical interlocking to achieve high-strength metal–polymer connections. In this method, porous copper is initially sintered onto copper plates, followed by the infusion of molten polymer into the pores, forming a robust copper–polymer bonded structure. Incorporating microneedle arrays into the copper plates further enhances the bond between the porous copper and the polymer. Characterization of the pore morphology and mechanical properties confirmed the formation of large-area 3D micro-interlocking. Tensile tests on samples with varying porosities showed connection strengths exceeding 30 MPa, with a maximum recorded strength of 37 MPa. Finite element analysis supported the high bonding strength and provided insights into failure mechanisms. This cost-effective technique offers superior copper–polymer bonding strengths, and introduces novel concepts for composite heat exchanger design and manufacturing.

Enhancing the efficiency of solar-powered water distillation units by utilization of waste heat

ABSTRACT Thermal water desalination is based on the evaporation and condensation of water, and such a process consumes a lot of energy, which lowers the economy of the process for commercial water desalination. The objective of this research is to improve the desalination energy efficiency of a novel domestic water desalination unit, which is based on thermal desalination, and this is done via utilization of the waste heat in the generated steam and reducing the operating costs. The distillation process begins with solar-powered evaporation of the salty water in the evaporator, followed by condensation of the generated water vapor coming from the evaporator over the cross-flow heat exchangers located in the condenser, which preheats the incoming saline water from the saltwater tank before it enters the evaporator. To assess the system's performance, comprehensive measurements are taken, including the electrical energy output from the PV panels and the volume of the output distilled water. Notably, the energy efficiency of the distillation is defined as the ratio of the heat energy gained by the distilled water, i.e. collected at the end of the day, to the electrical energy input to the electric heater, and it is found to be, on average, 82%.

Numerical computations on thermal performance of large-scale Ti-Mn-based metal hydride storage reactor via open source CFD software

Certain metals and metal alloys can absorb hydrogen through an exothermic chemical reaction, resulting in the formation of metal hydrides. To maintain a rapid charging rate, the produced heat must be extracted as rapidly as it is generated. This study was attempted to evaluate the heat transfer enhancement in a cylindrical hydrogen storage reactor equipped with a central tube for large-scale applications using a 3D transient model. Finite-volume simulations are carried out using the open-source software package OpenFOAM to systematically investigate the impacts of material thermophysical properties, cooling media, and heat exchanger design on the heat transfer behaviors and hydrogen storage rate. The reactor’s performance was evaluated in terms of temperature and total hydrogen mass history profiles, in addition to pressure drop. The findings indicated that the charging time was improved by roughly 86%, compared to the case without thermal enhancement to attain 90% hydrogen storage capacity. A diminished pressure drop was observed between the water-based Al2O3 nanofluid with 5 vol% concentration and pure water at lowered coolant flow velocities, hence enhancing pumping power efficiency. Moreover, the results demonstrated that the storage rate is markedly improved by enhancing the effective thermal conductivity of the hydride bed, increasing the heat exchange area, accelerating the coolant flow rate, and lowering its temperature. The outcomes highlighted the possibility of advancing the current metal hydride reactor for practical application.

Numerical Study on the Effect of Trapezoidal‐Wave Shaped Partition on Natural Convection Flow Within a Porous Enclosure

ABSTRACTThe use of a trapezoidal‐wave shaped diathermal partition to reduce natural convection flow and heat transfer within a fluid‐saturated, differentially heated porous enclosure is investigated in this study. This work is motivated by the need to control and reduce convective heat transfer in differentially heated porous enclosures, impacting applications like energy‐efficient building materials, thermal insulation, and improved heat exchangers. The study aims to disrupt convection currents and minimize thermal transfer. The Darcy flow model, representing fluid flow in porous media, is applied here and solved using the successive accelerated replacement (SAR) scheme with a finite difference method. Key parameters are varied to explore their effects on thermal and flow patterns. These parameters include the partition's length (with values between ), height (spanning from ), and distance from the left wall of the enclosure (), along with the modified Rayleigh number, which ranges from . Through computational visualization of streamlines and isotherms, this study examines how changes in partition geometry influence flow deviations. Results indicate that the trapezoidal partition allows flexibility in adjusting its geometrical parameters, effectively reducing convection flow strength without significant compromise. A drop of 41.13% in flow strength and about 56% reducted in heat transfer is achieved for trapezoidal partition with smaller edge length These findings suggest that such a partition setup can significantly improve thermal management in systems where fluid‐saturated porous enclosures are subject to differential heating.

Energy and exergy evaluation in a densified biomass burner using cocoa shells, intended for air heating for the artificial drying of food

Residual biomass as a renewable resource provides alternatives for energy generation, turning a problem into an opportunity for the industry. This study aims to analyze the energy and exergy performance of a biomass burner that uses cocoa shells as fuel for air heating and subsequent artificial drying of food. The study involves a conventional exergy analysis evaluating the energy performance of the equipment and proposing improvements to enhance the thermal efficiency of the system. The research consists of six phases: it begins with defining the input data of the system, followed by determining the thermodynamic properties of the working fluid (air), the exergies of the biofuel and the working fluid are calculated, energy and exergy balances are performed in the heat exchanger of the burner, and efficiencies are obtained. Finally, a sensitivity analysis is conducted to understand the burner’s behavior under different scenarios. The results showed an average exergy efficiency of 9.8%. By increasing energy efficiency in the sensitivity analysis, the outlet temperature rises to 164°C; however, exergy destruction decreases by 48.7%. One of the significant conclusions of this study proposes modifying the coil design to improve the exergy efficiency of the system due to its heat transfer capacity to the air.

Investigation of a Cogeneration System Combining a Solid Oxide Fuel Cell and the Organic Rankine Cycle: Parametric Analysis and Multi-Objective Optimization

A novel solid oxide fuel cell (SOFC)-based cogeneration system is proposed here, integrating an organic Rankine cycle for waste heat recovery. Technical–economic and parametric analyses are conducted, and a multi-objective optimization is carried out. The results reveal that the net electrical efficiency, investment cost, and payback time are 56.6%, USD 2,408,256, and 3.27 years, respectively. The parametric analysis indicates that the current density should be limited between 0.3 A/cm2 and 0.9 A/cm2, and the stack temperature should be controlled between 675 °C and 875 °C. After the operational optimization of ηele-CostTCI, the investment cost and the net electrical efficiency are obtained as USD 2,164,742 and 62.1%. After the ηele-PBT optimization, the payback period and the net electrical efficiency are 3.22 years and 58.9%. The heat transfer network optimization achieves the highest efficiency and reduces the cold utilities by 43 kW, but three additional heat exchangers should be added to the system. This research provides practical reference and pragmatic guidance for the integration, analysis, operation, and heat transfer network optimization of SOFC-based cogeneration systems.

CFD INVESTIGATION OF THE EFFECT OF MODIFIED TWISTED TAPE ON HYDROTHERMAL ENHANCEMENT IN VERTICAL PIPE

Heat transfer enhancement has been a significant focus in hydrothermal engineering for several decades. The current paper represents an investigation using computational fluid dynamics (CFD) for a vertical circular tube having twisted taper inserted (plain and modified) with different twisted tape ratios TR, i.e., 7.8, 3.9, and 2.6, at three uniform wall heat fluxes and ranges of Reynolds number as boundary conditions. The twisted strips were used as a system to produce a turbulent, powerful swirl flow with an increase in the intensity of the secondary flow at the radial direction of the tube. The (friction facto) f and (Nusselt number) Nu were two measures of pressure loss and heat transfer variation that have been studied and graphically depicted. So, to balance the heat transfer enhancement quantity with pressure losses, the performance evaluation factor PEF was tested. It was observed that the twisted tape insert enhances the radial secondary flow intensity. The findings demonstrated that, in every scenario, the increase in(Reynold number)Re at the inlet, heat flux quantity, and twisted ratio results from a proportionate increase in heat transfer. At the same time, the friction factor decreases with an increase in all boundary conditions, except the twisted ratio, where the friction factor increases with increasing heat transfer. After accounting for heat transfer and friction coefficient, it was discovered that the tube with modified twisted stripe and the twist ratio was 3.9 performs best out of all the configurations examined. The performance evaluation factor PEF of pipes inserted with modified twisted tape was higher, reaching 1.5. This study is based on enhancing a high-performance evaluation factor of heat exchangers for use in industrial settings.

Atmospheric Variability Drives Anomalies in the Bering Sea Air–Sea Heat Exchange

Abstract High latitudes, including the Bering Sea, are experiencing unprecedented rates of change. Long-term Bering Sea warming trends have been identified, and marine heatwaves (MHWs), event-scale elevated sea surface temperature (SST) extremes, have also increased in frequency and longevity in recent years. Recent work has shown that variability in air–sea coupling plays a dominant role in driving Bering Sea upper-ocean thermal variability and that surface forcing has driven an increase in the occurrence of positive ocean temperature anomalies since 2010. In this work, we characterize the drivers of the anomalous surface air–sea heat fluxes in the Bering Sea over the period 2010–22 using ERA5 fields. We show that the surface turbulent heat flux dominates the net surface heat flux variability from September to April and is primarily a result of near-surface air temperature and specific humidity anomalies. The airmass anomalies that account for the majority of the turbulent heat flux variability are a function of wind direction, with southerly (northerly) wind advecting anomalously warm (cool), moist (dry) air over the Bering Sea, resulting in positive (negative) surface turbulent flux anomalies. During the remaining months of the year, anomalies in the surface radiative fluxes account for the majority of the net surface heat flux variability and are a result of anomalous cloud coverage, anomalous lower-tropospheric virtual temperature, and sea ice coverage variability. Our results indicate that atmospheric variability drives much of the Bering Sea upper-ocean temperature variability through the mediation of the surface heat fluxes during the analysis period. Significance Statement A long-term ocean warming trend and a recent increase in marine heatwaves in the Bering Sea have been identified. Previous work showed that anomalies in the exchange of heat between the ocean and the atmosphere were the primary driver of Bering Sea temperature variability, but the processes responsible for the heat exchange anomalies were unknown. In this work, we show that the atmosphere is the primary driver of anomalies in the Bering Sea air–sea heat exchange and therefore plays an important role in altering the thermal state of the Bering Sea. Our results highlight the importance of understanding more about how the ocean and the atmosphere interact at high latitudes and how this relationship will be affected by future climate change.

Geothermal Condition Investigation and Resource Potential Evaluation of Shallow Geothermal Energy in the Yinchuan Area, Ningxia, China

Shallow geothermal energy (SGE) is a promising green and sustainable energy source, gaining prominence in light of the dual-carbon target. This study investigated the SGE resources in the Yinchuan area. Suitability zones and the potential of SGE resources were determined based on the comprehensive analysis about thermophysical parameters, hydrogeological conditions, and geological environment. Our findings revealed that the effective thermal conductivity in the Yinchuan area surpasses those of other cities, indicating significant potential for SGE. The thermostat layer depth ranges from 40 to 60 m, with a geothermal gradient between 0.81 and 6.19 °C/100 m. Regions with poor adaptability for a borehole heat exchanger (BHE) are mainly distributed in the western and southern parts of the Yinchuan area, whereas moderately and highly adaptable areas are primarily located in the central and eastern areas, respectively. The total geothermal resource of the BHE in the Yinchuan area amounts to 1.07 × 108 GJ/a, generating significant economic benefits of 1.07 × 109 CNY/a and saving 1.09 × 106 t/a of standard coal annually. This initiative leads to significant reductions in CO2, SO2, and NOx emissions by 2.61 × 106 t/a, 1.86 × 104 t/a, and 6.57 × 103 t/a, respectively. Additionally, it results in potential savings of 0.309 × 109 CNY/a in environmental treatment costs. The methods and models used in this study have potential for similar geothermal surveys in arid and cold regions. The results also contribute essential insights for policy formulation and sustainable development strategies related to shallow geothermal resources in the Yinchuan area.

Numerical Investigation of a Heat Exchanger with Annular Fins for Cryocooler Application

In this paper, the heat transfer characteristics of a typical hot heat exchanger used in pulse tube cryocooler have been numerically investigated. The numerical simulation is performed with the help of the commercial tool Ansys Fluent® to study the effect of different shapes and sizes of fins on the rate of heat transfer. The major parameters of the analysis include the diameter and pitch of the fins, the oscillating temperature at the inlet and outlet of the heat exchanger, and its operating frequency. A numerical investigation is conducted for the annular fin to illustrate its effect on the rate of heat transfer by calculating its Nusselt number and heat transfer coefficient. The effect of with fin and without fin on temperature and pressure variations has been studied for different angles in a cycle. The vortex development mechanisms within the gap between fins have been analyzed and compared with the vortex development mechanisms without fin. Results will be helpful for better design of heat exchangers for cryocoolers.

Features of Motion and Heat Transfer of Swirling Flows in Channels of Complex Geometry

The computational and experimental study results of swirling single-phase coolant motion and heat transfer for the standard operation parameters of a nuclear power plant are presented. The experimental model is a vertical heat exchanger of a “pipe in a pipe” type with the countercurrent movement of coolants. Six different swirlers (three with a constant twist pitch and three with a variable pitch) were considered. The heat exchanger temperature field was measured at various combinations of coolant flow rates, and a channel pressure drop for each swirl was determined. Computational studies were performed using the Omega-based Reynolds stress model and SST model with a correction for curvature streamlines. A good agreement between numerical and experimental data was obtained. Based on the velocity and temperature fields, swirling flow motion features in channels with a variable swirl pitch were discovered. For each intensifier, the effectiveness criterion in comparison with a pipe channel was determined.

Development of heat exchanger modelling capability for a finite volume aeroelasticity solver

Abstract Heat exchangers are frequently used in aero engines and are known to significantly affect the surrounding steady and unsteady flow. In certain applications, they may thereby also influence the aeroelastic stability of upstream or downstream components but there is limited research on this in the public domain. This paper aims to demonstrate the influence of heat exchangers on unsteady flows relevant to aeroelastic problems. This is achieved by developing heat exchanger modelling capability for an in-house finite volume aeroelasticity solver, for which heat exchanger is represented as a porous medium, as this is the established approach in existing aerodynamic studies using commercial CFD software. The governing equations for a Darcy-Forchheimer porous media model suitable for unsteady and compressible flows are presented, which are derived by the application of volume averaging theory to the Navier-Stokes equations. The implementation of this model within the time integration method used for the solver is then described and verified by comparison of results for steady flows against an established commercial CFD solver, where close agreement between both in-house and commercial solvers has been observed. Lastly a preliminary demonstration of the capability to model unsteady heat exchanger flows is presented by application to an aeroacoustic problem, where the interaction of the pressure waves and the heat exchanger is investigated.

Design Optimization of a Shell-and-Tube Heat Exchanger Based on Variable Baffle Cuts and Sizing

Abstract This article investigates the optimization of a shell-and-tube heat exchanger design through the optimization of baffle spacing and cut. This study focuses on the impact of baffle spacing (20–35%) and baffle cut percentage (20–35%) on heat transfer performance while considering the effect of the presence or the absence of seals. This study aims to optimize the heat exchanger design by using computational fluid dynamics (CFD) to reduce the pressure drop and increase the heat transfer. Studying the flow in heat exchangers is challenging due to its complex physics, especially in nonstandard geometries or novel fluid systems, which makes traditional methods relatively less accurate compared to modern approaches. The following fluid is so far uninvestigated for CFD analysis of heat exchangers: a mixture of 80% ethanol and 20% water is used as the tube-side fluid and water is used as the shell-side fluid. The Bell–Delaware method is employed for initial thermal analysis, followed by CFD simulations using ansys fluent to assess the influence of design modifications on heat transfer efficiency and pressure drop. The presence of seals is shown to improve the heat transfer efficiency by about 10.9% compared to the case when seals are absent, while optimal baffle spacing and baffle cuts are able to increase the efficiency of the heat exchanger by about 110% not inclusive of the effect of seals. Our findings show that the performance of a shell-and-tube heat exchanger is improved dramatically by the addition of seals and optimal selection of baffle cut and spacing.

Copper corrosion mechanisms, influencing factors, and mitigation strategies for water circuits of heat exchangers: critical review and current advances

Abstract This review examines copper corrosion mechanisms and their key influencing factors, including microstructure effects, surface treatments, manufacturing conditions, temperature, water chemistry parameters, fluid velocity, and microbial effects in water-based systems, with a particular focus on heat exchangers. This addresses a critical gap in the existing literature, which often examines copper corrosion in a broader context. By critically analyzing the literature, the review provides an in-depth understanding of the factors that govern copper corrosion in heat exchanger applications. Copper corrosion in heat exchangers can have significant technical and social detrimental consequences, leading to substantial economic losses. By focusing on heat exchangers, the review offers valuable insights and best practices for engineers, researchers, and practitioners working with copper in this domain. Furthermore, the review evaluates the latest mitigation strategies, including advancements in material selection, surface treatments, water treatment techniques, and robust monitoring/maintenance methods. Finally, the review explores promising new concepts for corrosion prevention for long-term performance, paving the way for future research in developing innovative technologies and refining highly effective strategies under diverse operating conditions relevant to combat deleterious copper corrosion effects in heat exchanger applications.