Types Of Exchangers Research Articles

Efficiency Enhancement in Ocean Thermal Energy Conversion: A Comparative Study of Heat Exchanger Designs for Bi2Te3-Based Thermoelectric Generators.

This research focuses on enhancing the efficiency of Bi2Te3-based thermoelectric generators (TEGs) in ocean thermal energy conversion (OTEC) systems through innovative heat exchanger designs. Our comparative study uses computer simulations to evaluate three types of heat exchangers: cavity, plate-fins, and longitudinal vortex generators (LVGs). We analyze their impact on thermoelectric conversion performance, considering the thermal energy transfer from warm surface seawater to TEGs. The results demonstrate that heat exchangers with plate-fins and LVGs significantly outperform the cavity heat exchanger regarding thermal energy transfer efficiency. Specifically, plate-fins increase TEG output power by approximately 22.92% and enhance thermoelectric conversion efficiency by 38.20%. Similarly, LVGs lead to a 13.02% increase in output power and a 16.83% improvement in conversion efficiency. These advancements are contingent upon specific conditions such as seawater flow rates, fin heights, LVG tilt angles, and locations. The study underscores the importance of optimizing heat exchanger designs in OTEC systems, balancing enhanced heat transfer against the required pump power. Our findings contribute to a broader understanding of materials science in sustainable energy technologies.

Design and performance analysis of a discontinuous spiral baffle heat exchanger

In this paper, a new type of heat exchanger with discontinuous spiral baffles is designed, and its performance on heat transfer is analyzed by numerical simulation. The research results show that the airflow in shell-side flows by a similar helical way, “Flow dead zone” is not found. The high enthalpy airflow’s temperature decreases about 38% of the inlet air temperature by cooling down with a convective heat transfer coefficient of 344.4 W/(m2·K), while the decrease of the airflow pressure is 30%.

Mapping the evolution of university-industry collaboration: A systematic literature review from 2000 to 2022

This research aims to improve knowledge exchange and innovation through collaborations between universities and industries in South-East European Countries (SEECs). The region benefits from better collaboration, and understanding factors such as proximity, motivations, and challenges is crucial. The study begins by suggesting that geographical closeness may influence the strength of university-industry ties and that specific conditions in SEECs may either support or impede these relationships. The paper proposes a new University-Industry Collaboration (UIC) model tailored for SEECs, built upon a review of literature from 2000 to 2022. This review examines factors like location, organizational approaches, types of knowledge exchange, key motivators and barriers, and the evolving role of universities in the region. The study introduces a specialized UIC model that could enhance regional cooperation, emphasizing strategies to overcome barriers and align university and industry goals. By extensively reviewing existing research, the paper contributes valuable insights into UIC in SEECs, aiming to deepen the understanding of these collaborations in the region.

Investigation of Heat Exchanger Performance in The Heating Tank Section of Loop FASSIP 03 NT

The Passive System Simulation Facility (FASSIP) loop is an experimental test facility for a passive cooling system to recover the residual heat from decay produced by the reactor core during accident conditions. The Heating Tank Section (HTS) is one of the components of the FASSIP 03 NT facility. This component is equipped with a heat exchanger, 3 types of heat exchangers can be applied to HTS. Namely heat exchangers of the Straight Pipe Heat Exchanger (SPHE) type, the Straight Pipe Fins Heat Exchanger (SPFHE) type, and the Helical Pipe Heat Exchanger (HPHE) type. A modification was made to increase the efficiency of HTS, namely replacing the electric heater on the HTS from a ceramic band heater type to an immersion heater type. With this modification, it is necessary to know the performance of the heat exchanger on HTS and its speed in reaching operational temperature. The HPHE-type heat exchanger is more efficient than the SPHE-type and SPFHE-type heat exchangers. The HPHE-type heat exchanger has a much larger length of 5.5 m, so the thermal resistance (Rth) is very small, namely 0.003926 ℃/W. To reach the working fluid temperature in the range of 50 – 90 ℃, the HPHE-type heat exchanger requires 35 – 86 minutes.

Refining a Framework to Enhance Communication in the Emergency Department During the Diagnostic Process: An eDelphi Approach

Emergency departments (EDs) are susceptible to diagnostic error. Suboptimal communication between the patient and the interdisciplinary care team increases risk to diagnostic safety. The role of communication remains underrepresented in existing diagnostic decision-making conceptual models. The authors used eDelphi methodology, whereby data are collected electronically, to achieve consensus among an expert panel of 18 clinicians, patients, family members, and other participants on a refined ED-based diagnostic decision-making framework that integrates several potential opportunities for communication to enhance diagnostic quality. This study examined the entire diagnostic process in the ED, from prehospital to discharge or transfer to inpatient care, and identified where communication breakdowns could occur. After four iterative rounds of the eDelphi process, including a final validation round by all participants, the project's a priori consensus threshold of 80% agreement was reached. The authors developed a final framework that positions communication more prominently in the diagnostic process in the ED and enhances the original National Academies of Sciences, Engineering, and Medicine (NASEM) and ED-adapted NASEM frameworks. Specific points in the ED journey were identified where more attention to communication might be helpful. Two specific types of communication-information exchange and shared understanding-were identified as high priority for optimal outcomes. Ideas for communication-focused interventions to prevent diagnostic error in the ED fell into three categories: patient-facing, clinician-facing, and system-facing interventions. This project's refinement of the NASEM framework adapted to the ED can be used to develop communications-focused interventions to reduce diagnostic error in this highly complex and error-prone setting.

Loss of 24-hydroxylated catabolism increases calcitriol and fibroblast growth factor 23 and alters calcium and phosphate metabolism in fetal mice.

Calcitriol circulates at low levels in normal human and rodent fetuses, in part due to increased 24-hydroxylation of calcitriol and 25-hydroxyvitamin D by 24-hydroxylase (CYP24A1). Inactivating mutations of CYP24A1 cause high postnatal levels of calcitriol and the human condition of infantile hypercalcemia type 1, but whether the fetus is disturbed by the loss of CYP24A1 is unknown. We hypothesized that loss of Cyp24a1 in fetal mice will cause high calcitriol, hypercalcemia, and increased placental calcium transport. The Cyp24a1+/- mice were mated to create pregnancies with wildtype, Cyp24a1+/-, and Cyp24a1 null fetuses. The null fetuses were hypercalcemic, modestly hypophosphatemic (compared to Cyp24a1+/- fetuses only), with 3.5-fold increased calcitriol, 4-fold increased fibroblast growth factor 23 (FGF23), and unchanged parathyroid hormone. The quantitative RT-PCR confirmed the absence of Cyp24a1 and 2-fold increases in S100g, sodium-calcium exchanger type 1, and calcium-sensing receptor in null placentas but not in fetal kidneys; these changes predicted an increase in placental calcium transport. However, placental 45Ca and 32P transport were unchanged in null fetuses. Fetal ash weight and mineral content, placental weight, crown-rump length, and skeletal morphology did not differ among the genotypes. Serum procollagen 1 intact N-terminal propeptide and bone expression of sclerostin and Blgap were reduced while calcitonin receptor was increased in nulls. In conclusion, loss of Cyp24a1 in fetal mice causes hypercalcemia, modest hypophosphatemia, and increased FGF23, but no alteration in skeletal development. Reduced incorporation of calcium into bone may contribute to the hypercalcemia without causing a detectable decrease in the skeletal mineral content. The results predict that human fetuses bearing homozygous or compound heterozygous inactivating mutations of CYP24A1 will also be hypercalcemic in utero but with normal skeletal development.

Multi-Criteria Study on Ground Source Heat Pump with Different Types of Heat Exchangers

Heat pumps are currently one of the most frequently applied heat sources in residential buildings. Ground source heat pumps are more reliable than air source heat pumps in terms of energy efficiency, especially in colder climates. However, they are more expensive and involve increased material inputs; therefore, multi-criteria analyses taking into account environmental and economic aspects seem necessary for the green design of these systems. The aim of this work was to analyze the environmental and economic impacts of the ground source heat pump providing heating for a family house located in eastern Poland, cooperating with three types of ground heat exchangers (each in two sizing options): helix, vertical and horizontal. The multi-criteria analysis was based on the life cycle assessment methodology using IMPACT 2002+ and life cycle costs methods. The lowest environmental impact was reported for the variants with vertical ground heat exchangers, mainly due to their high efficiency in the operation stage. On the other hand, the lowest economic impact was observed for the horizontal heat exchangers, which are not demanding in terms of material and construction costs. Final recommendations based on multi-criteria analysis propose the vertical probes as a sustainable solution, with a weighted sum indicator in the range 0.085–0.297 on 0–1 scale.

Using different geometries on the amount of heat transfer in a shell and tube heat exchanger using the finite volume method

This research investigates the heat transfer and pressure drop characteristics of a conical spiral tube heat exchanger. The study specifically focuses on the application of Ag-HEG (Silver–Hydrogen exfoliated graphene) nanofluid and various turbulator designs. The range of Dean Numbers, specifically 2200 < Dean <4200, was studied through experiments under turbulent flow conditions. Furthermore, the finite volume method-based ANSYS Fluent commercial code was utilized for numerical simulations. Additionally, numerical simulations were performed using the ANSYS Fluent software, which utilizes the finite volume method. This research aims to perform a numerical analysis on the efficiency of a conical shell and tube heat exchanger. When compared to other models, spiral heat exchangers provide a larger contact area between the fluid and the exchanger within a specified occupied area. This advantage is one of the prominent features of this particular type of heat exchanger. The simulations were conducted in two stages. During the first stage, the thermal performance coefficients of three turbulators were evaluated. In the second stage, the four-blade turbulator with ten revolutions, which exhibited superior thermal performance, was further analyzed based on the number of circles around the center of the conical spiral coil. The numerical results showed that the four-blade turbulator with ten revolutions displayed superior thermal performance compared to the other modes, specifically the two-blade and three-blade turbulators. In the second stage, it was found that the Nusselt number achieved from 30 revolutions was higher by 4.2 %, 10 %, and 18.3 % compared to the Nusselt numbers obtained from the other two modes of 10 and 20 revolutions. Consequently, it is concluded that utilizing Ag-HEG nanofluids in conjunction with the four-blade turbulator featuring 30 revolutions is the optimal choice for improving heat transfer in conical spiral tube heat exchangers while maintaining an acceptable level of pressure drop. This combination outperforms traditional fluids and turbulators.

Feasibility Study of New Geothermal System for Heating Premises and Thermal Complexes: Experimental Investigation of Water-Air Heat Exchanger in the East of Algeria

Abstract This paper constitutes a new technological solution for the exploitation of one of the most important geothermal deposits located in the locality of Biskra (South-east Algeria). This is the Albian aquifer whose hot waters from boreholes, hot springs and spas are poorly exploited while ambient temperatures during winter periods reach very low levels, especially at night. The principle of this geothermal system is to immerse a PVC tubular water-air exchanger in a pool permanently supplied with hot water from a low-energy geothermal borehole with a high flow rate. The choice of PVC material is attributed to the fact that hot geothermal waters are generally of an aggressive composition to steels and metals in general. The geothermal air heater allows the heating of the ambient cold air which is introduced into the exchanger and then extracted hot using an extraction fan. The hot air is then diffused into premises for heating during the winter season. The improvement in the performance of this type of exchanger is highlighted, in particular by acting on the number of pipes of the exchanger and the air flow rate using geothermal energy (low energy) as a source of renewable and clean energy. The experimental results obtained showed that the energy gain is a function of the length of the exchanger and the air flow rate. This gain can be up to 20°C between the inlet and outlet of the miniature exchanger model, which means that the proposed solution could be technically feasible.

Theoretical and experimental study on a novel evaluation criteria of heat exchangers applied in aero engines

For the application of heat exchangers in the aeronautic field, an effective evaluation method is required to support the satisfaction of the multi-aspect design restrictions including the thermal and hydraulic performance, occupied volume, total weight, etc. To weigh the benefit and cost for both heat transfer units and heat exchangers, this study thus proposes three evaluation indexes Rp, RV, and Rm defined by the product of heat transfer coefficient and heat transfer area of unit windward area times pressure drop (hA/(AfrontΔp)), that of unit volume (hA/V) and that of unit weight (hA/m). Considering the factors h and A comprehensively and excluding the influence of mean differential temperature, the three indexes can reflect the low flow resistance, compactness, and lightness characteristics under fixed operating conditions and heat transfer duty requirement accordingly. A validation experiment is carried out and the deviation between the evaluation and experiment results is less than 10.88% for the three indexes. To show the applicability, a detailed evaluation of six different heat transfer units and five types of heat exchangers is conducted. A heat transfer unit selection method based on the new indexes is provided finally for heat exchanger design.

Entropy generation minimization for different types of heat exchangers using nanofluids

ABSTRACT In view of the current global energy situation, increasing the efficiency of heat exchangers can contribute significantly to reducing energy consumption and greenhouse gas emissions. In this study, the effects of nanofluids (SiO2/Water) prepared at different fluid flow rates and different volumetric concentrations (vol.%0.1-0.2-0.3) on three heat exchangers (Shell and Tube, Double Pipe, Plate) with the same capacity were investigated experimentally and statistically. It was concluded that there was an increase of 47% in effectiveness and 87.3% in NTU value with the increase in the volumetric concentrations of nanofluids and fluid flow rate. With the use of nanofluids, it was observed that entropy production decreased by up to 56.08%. The results obtained were analyzed using Response Surface Methodology (RSM) and mathematical models were created and the prediction capabilities of the models were 98% and above. Entropy minimization was performed using statistical methods and it was statistically determined that plate heat exchangers give better results among heat exchangers with the same capacity. It is concluded that the entropy production is minimum when the fluid flow rate is 2 lpm, the volumetric concentration is 0.3% and a plate heat exchanger is used. This study has provided a different and comprehensive perspective on heat exchangers, and it is thought that it will give many ideas to researchers working in this field.

Development and experimental investigation of full-scale phase change material thermal energy storage prototype for domestic hot water applications

The paper presents an experimental analysis of the full-scale phase change material (PCM) thermal energy storage (TES) prototype that is designed for use in domestic hot water preparation systems. The PCM-TES prototype is based on the external arrangement of organic PCM and a custom-made compact fin-and-tube type of heat exchanger. The prototype has been designed, constructed, and tested according to the Ecodesign Directive requirements for water heaters and hot water storage tanks. Several parameters have been analysed, including the heat transfer fluid (HTF) temperature and mass flow rate, heat transfer rate, accumulated and released energy, and quantity of domestic hot water (DHW) delivered. Additional attention was paid to the reliability and repeatability of the results. Experimental research allowed to determine the quantity and temperature of DHW at a constant mass flow rate of 0.1 kg/s. The prototype unit showed that it can deliver 99.1 l of hot water at 40 °C for up to 15 min and 39 s, while the use of lower temperature DHW (up to 37 °C) allows to increase the quantity of hot water delivered up to 156.2 l. Experimental results showed the viability of the prototype, areas for improvement and further possibilities for its optimization. Overall, the study results are relevant for developing latent heat thermal energy storage systems using fin-and-tube heat exchangers in tanks and the feasibility of integrating such systems into DHW systems.

Energy saving when using equipment for the disposal of low-potential waste heat

The article discusses the problem of energy saving in the context of comparing different types of heat exchangers for the utilization of high-potential waste heat. The advantages and disadvantages of various regenerative ventilation schemes are analyzed and the most efficient heat exchangers are proposed for use in various fields. These include various types of regenerative heat exchangers. The factors influencing reliability and creation of optimal operating modes with high energy savings are considered. Recommendations for the use of enthalpy heat exchangers with the required technical characteristics are given. Various types of nozzles are shown to ensure better efficiency. The advantages and disadvantages of regenerative heat exchangers with an intermediate carrier and techniques for reducing the cost of manufacturing such structures are considered. The areas of application of small-sized plate heat exchangers are given. The principle of operation of heat exchangers on heat pipes (HHP) and their technical characteristics are considered. A compactness criterion has been introduced, which allows comparing different types of heat exchangers. The instantaneous boiling apparatus for the utilization of low-potential internal (by-product) energy resources (IER) and possible applications are considered in detail. In all cases of using the considered schemes, the prospects for their development in industry are noted.

CFD Analysis of the Effect of Mass Flow Rate in a Shell and Tube Heat Exchanger Design

Heat exchangers are often found in the chemical process industry, but of all types of heat exchangers, the Shell and Tube Heat Exchanger (STHE) are the most used. The design of shell and tube heat exchangers are continually evolving because of it reduce production costs. A computational fluid dynamics (CFD) simulation was employed using SOLIDWORKS Flow Simulation version 2022 to model the effect of operating parameter such as the mass flow rate on the pressure drop, heat transfer coefficient and the turbulence intensity. The turbulence model adopted for the simulation was the k–ɛ turbulence model incorporating the boundary conditions. Three conditions were studied increasing both shell and tube side mass flow rate, maintaining either the shell or tube constant and then varying the other. The results obtained showed that an increase in mass flow rate have tremendous effect on the pressure drop, heat transfer and turbulence intensity.

Towards a Conceptual Model of AI-Mediated Knowledge Sharing Exchange of HRM Practices: Antecedents and Consequences

Increased adoption of artificial intelligence (AI) enabled human resource management (HRM) has moved from developing functional applications to actively engaging employees in their use of such applications. Employees share explicit and tacit knowledge using an AI-mediated knowledge sharing (AI-MKS) exchange through HRM-focused AI applications. However, there exists limited understanding of the antecedents and outcomes of such an AI-MKS exchange. Research on this topic is timely as emerging research points to mixed (positive and negative) effects of such technological adoption. Therefore, this article employs a dual review strategy, wherein a narrative review follows a systematic literature review to develop a theoretical model for understanding the causes and consequences of an AI-mediated knowledge-sharing exchange using AI-enabled HRM applications. We integrate the theoretical literature on knowledge sharing, HRM, and AI-mediated social exchange for building our theoretical model. Specifically, the systematic literature review points to an individual, social, technological, and organizational level antecedents of knowledge sharing, which interact with various types of an AI-MKS social exchange to deliver high levels of personalization, hyperpersonalization, and individualization for employees as well as deliver HR effectiveness.

EXPERIMENTAL INVESTIGATION ON THE APPLICATION POTENTIAL OF FINLESS HEAT EXCHANGER WITH MINI-DIAMETER TUBES UTILIZED AS AIR HEATER OR AIR COOLER

Increasing the ratio of the internal and external surface areas of heat exchangers is ordinarily considered to be an effective way of improving performance. In this paper, a novel finless heat exchanger with mini-diameter tubes used as air heater or air cooler is proposed. In order to fully understand the performance of this novel type of heat exchanger, a test bench was established. The heating and cooling performances were tested according to relevant standard specifications. Furthermore, the heat exchanger was compared with seven conventional heat exchangers. This novel heat exchanger has excellent surface heat transfer temperature difference uniformity. Relative to the seven traditional heat exchangers examined, this novel design demonstrated remarkable heat transfer enhancements, registering gains of at least 173&amp;#37; as an air heater and a staggering 277&amp;#37; as an air cooler. However, it also exhibited elevated waterside flow resistances. Critically, conventional empirical heat transfer equations proved suboptimal for this system, necessitating modifications that yielded new coefficients: C &amp;#61; 0.0839 and n &amp;#61; 0.992.

A novel Ground Source heat exchanger in an underground metro tunnel

Using Ground Coupled Heat Pump (GCHP) systems in urban areas can be particularly difficult due to space or legislative constraints, other than excessive costs due to drilling. To overcome these problems, the authors proposed to use Artificial Ground Freezing (AGF) probes, used for tunnel excavation, as Ground Heat Exchangers (GHE). It is a widespread practice to seal the probes in the tunnel after the completion. The conversion of existing AGF probes into GHE for GCHP allows us to avoid additional drilling costs, and other space or legislative constraints associated with the use of GCHP systems in urban areas. Such systems could be developed to use underground urban transportation tunnels for heating and cooling in smart cities. These systems were tested after the construction of two tunnels, as part of the GeoGRID project, in Piazza Municipio, Naples, Italy. The data obtained from the experimental setup have been analysed and used for validation of a finite element model developed by the authors to simulate heat transfer between the probes and the surrounding ground. A simplified pipe flow model was introduced, in combination with a 3D model of the ground, to reduce the complexity and computational effort to solve the discretized equations. The simulation results have been compared with experimental data, showing a good agreement, and observing differences in the range of 2 – 5 %. The model can therefore be used as a predictive tool for the development of this type of innovative heat exchanger.

Problems and prospects of decarbonization of road transport in the Russian Federation

On the way of decarbonization of certain sectors of the economy, new types of climate risks arise, and associated losses as a result of actions by the public and private sectors aimed at containing these changes, and not at adapting industries to climate change. Measures for decarbonization of motor transport are considered. The most effective of them in the medium term are measures to diversify the use of natural gas, traction electric drive and hydrogen fuel cells as energy sources. The key organizational, technological and economic problems that hinder the widespread use of these alternative energy sources in road transport are highlighted. The requirements for achieving the competitiveness of cars with traction electric drive and hydrogen fuel cells in comparison with oil-fueled cars are formulated.It has been established that the total gross GHG emissions of the Russian vehicle fleet in 2050, the expected number of which will decrease from 59.8 to 51.7 million units compared to 2021, may amount to 126.8 million tons of CO2 equivalent, which is 28.5 % less than in 2021. Compared to previous projections, the value of total GHG emissions from the vehicle fleet in 2050 will lag behind by about 5 years. At the same time, the vehicle fleet in 2050 will be dominated by automatic telephone exchanges with internal combustion engines on hydrocarbon fuels (liquid, gaseous). Only after 2045, the share of sales of electric vehicles of all types can exceed the share of sales of these types of automatic telephone exchanges with internal combustion engines [1].

Numerical Study on Fracture Behavior of Printed Circuit Heat Exchanger Core Based on Elasto-Plastic Phase Field Method

Abstract Printed circuit heat exchanger (PCHE) is a type of compact heat exchanger with high thermal efficiency, more compact, and suitable for high pressure and high temperature conditions. The safety assessment of PCHE is very important, especially for PCHE core. Because PHCE core is different from the PCHE headers which are typical pressure vessel components. However, there is no standard design method to ensure the structural integrity for PCHE core. Some failure modes of PCHE core are studied in recent years, but seldom researches have been conducted concerning the fracture behavior of PCHE core. In addition, the phase field method for fracture has developed rapidly in recent years with its advantages in predicting crack initiation, bifurcation, and merging. In this work, the fracture behavior of PCHE core with and without defects is investigated based on elasto-plastic phase field method. The model parameter of Ni-based Alloy for elasto-plastic phase field method is first calibrated by comparing the numerical results with tensile test data of diffusion-bonded PHCE core specimen. Then, the influence of loading directions, defect locations, and defect sizes on the fracture behavior of PCHE core with semicircular and semicircular-rectangular channels are analyzed. Some conclusions are discussed.

Establishing sustainable collaborations in global pathology education.

Graduate-level pathology education is under-resourced in low/middle-income countries (LMIC) and provides a unique opportunity for building sustainable collaborations. By focusing on a bi-directional educational exchange through graduate medical training in Pathology and Laboratory Medicine (PALM), global collaborations can extend to research and scholarship efforts. There are few PALM-based graduate medical programs in high-income countries (HIC) that offer this type of global educational exchange, and the few that exist have been mitigated by pandemic-related travel restrictions. Nonetheless, re-investing in these types of exchanges will allow for new opportunity in global pathology education and research for the next generation of trainees. Drawing on the author's own experience in South Africa and Guatemala, five essential elements to establish a sustainable educational collaboration will be discussed: sustained effort and communication between partners of HIC and LMIC, involvement of key stakeholders, educational curriculum involving community engagement and cultural competency, bi-directional exchange between partners, and dedicated time and funding.