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In this paper research has been conducted by varying the internal design of the pipes that are used in the compact air to air heat exchanger to see if the addition of turbulizers in the internal section can result in an improvement in the ΔT at the exit of the pipe. We are also looking at the internal flow characteristics of the air inside the heat exchanger pipes. The drop in pressure at the exit of the pipes because of the addition of the turbulizers has also been investigated. All these analysis have been performed using the commercial software package ANSYS CFX and the results are presented in this paper. [ABSTRACT FROM AUTHOR]

Pipes in heat exchanger systems are usually made of metallic materials to achieve a high level of thermal conductivity and thus high efficiency. However, substitution with polymer materials has a great potential. Plastics save weight, can be produced at lower cost and emissions, and are ideal for use in corrosive or chemically aggressive environments, where most metals fail. The challenge, however, is their much lower thermal conductivity in comparison. To reduce this disadvantage, fillers are used to transport thermal energy through the less conductive polymer matrix. In fact, high filler ratios are required to achieve an acceptable level of thermal conductivity for heat exchanger systems. However, these high filler ratios have a significant impact on the material properties of the polymer, such as the flexibility, which is drastically reduced. The result is a brittle material with limited suitability for use in heat exchanger systems. This paper describes a novel approach to effectively increase the thermal conductivity of polymer materials by optimizing the orientation of anisotropic filler particles by die design. Standard pipe extrusion dies result in continuous shear forces in the direction of extrusion. Accordingly, the resulting filler network has a higher thermal conductivity in the axial direction of the pipe than radially through the pipe wall. However, radial heat transfer is essential in pipe heat exchanger systems. To improve this, various die designs for targeted radial alignment of filler particles are discussed in this paper. Furthermore, the potential for improvement of the die designs is investigated. So far, the most efficient die design achieves an increase in thermal conductivity of up to 74 % compared to a standard pipe extrusion die. [ABSTRACT FROM AUTHOR]

The paper presents an approach to the optimal design of multi-stream heat exchangers used in low-temperature technologies. The design process consists in creating the computational model of multi-stream heat exchangers with heat transfer fluids described in the paper, analyzing and selecting optimality criteria, investigating the influence of all possible mutual flow directions and directly selecting optimal design and operating parameters according to the specified criteria. The process has been demonstrated on the example of a three-flow plate fin heat exchanger used in a natural gas liquefaction scheme. Elements of multi-criteria optimization have been applied. Two optimal variants have been obtained, the first one being in terms of energy indicators, the second one being in terms of productivity. [ABSTRACT FROM AUTHOR]

Earth-to-air heat exchangers (EAHE) are passive technologies used to cool and heat buildings. This paper aims to review published research on this topic. The review has structured into several sections that focused on the use of numerical evaluation of the performance of the earth tube heat exchanger in the ventilation of the buildings. The review also dealt with the results of studies that concentrated on the heat exchanger performance within different burial depths, the impact of soil, climate characteristics on the heat exchanger performance, and the effect of the merging mechanism adopted with the building (direct or with the cooling and heating systems attached to it). Finally, the paper reviewed the final conclusions reached by the researchers. [ABSTRACT FROM AUTHOR]

Since the 1990's, nanofluids have been one of the abundantly preferred newcomer technology invented to assist in electronic and heat transfer purposes. Their thermophysical properties and heat transfer performance make nanofluids highly demanded to overcome the current issues in the world. In this paper, a vast number of applications using nanofluids are reviewed as well as an epitome on the challenges in their respective areas. Additionally, recent research papers for specific applications of nanofluids in improving heat transfer efficiency were outlined while the experimental and theoretical methods were discussed in the articles and journals is summarized in this paper including the effects of thermal properties on the performance of nanofluids. In a nutshell, this review of experimental research extracted from most recent papers, published from 2011 to 2016, is a review on the latest updates in the nanofluids and heat transfer community to help anyone in concern of the topic and enough information to select nanofluids based on their needed applications. [ABSTRACT FROM AUTHOR]

The Fukushima Daiichi accident in 2011 indicated the limited use of passive system to remove the core decay heat in form of a heat exchanger submerged in a water pool for a long-term period. A heat pipe design, which is proven to be effective in absorbing heat passively in the small device application, is the object of this research. The wickless heat pipe in form of two-phased closed thermosyphon (TPCT) requires normally a large-scale dimension to perform its function as passive decay heat removal device. For that purpose, a TPCT experimental setup has been established using the external pool water as the heat source, which is heated around the TPCT evaporator section. The objective of this paper is to explain the TPCT experiment results in performing the heat exchange in an assumed spent fuel pool and to compare them with the thermal-hydraulic code of RELAP5, which is normally used in the nuclear reactor safety analysis. The RELAP5 simulation of the TPCT model with the 30 % and 60 % filling ratio has performed well in reducing the boiling process of pool water, which is heated by a constant 6000 Watts heat load. After several modelling process, the validation of the RELAP5 model with the experimental results of similar filling ratios requires the initial condition option involving the non-condensable gas beside the water/steam inside the TPCT volume. This improved model has provided a more stable and closer trendlines when comparing the effect of filling ratio with the TCPT wall temperature in the evaporator, adiabatic, and condenser section. Another research is proposed to include a more exact value of the non-condensable gas in the calculation. Differences between simulations and experimental data could be caused by factors of heat transfer inside the pool water volume and modelling of heat load input. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study on heat exchangers based on fins, open-cell metal foam and thermal interface material (TIM). Experiments were conducted on the copper foam of 40 PPI with 1 mm thickness plate fins and two commercial TIMs (pad types) with thermal conductivities of 5 and 12 W/mK. Different compact fin copper foam heat exchanger configurations were tested at varying Reynolds numbers. The heat exchanger and a test rig were designed and fabricated in-house. The results show that the fin copper foam heat exchanger with TIM 12.8 W/mK thermal conductivity has the maximum Nusselt number, 923.66, at a Reynolds number of 25,677. It has achieved the highest heat transfer performance among other configurations of heat exchangers. The fin copper foam heat exchanger with the same TIM has the maximum pressure drop at the same Reynolds number, which was 261.96 Pa, due to the limitation of the amount of air that can pass through the heat exchanger due to fins and foams. This study shows that joining metal foam and fin with TIM in a heat exchanger can increase the surface area between mating parts and thus increase heat transfer. It also provides insights into an alternative means of joining metal foams with other metals (or a base plate) to develop high-performance heat exchangers. [ABSTRACT FROM AUTHOR]

The main objective of the study was to examine the thermophysical properties of Alder wood specimens as they relate to their volumetric density. Wood samples were subjected to controlled exposure conditions to assess their behavior after storage under room conditions of around 65% air humidity and a temperature of 20°C. This paper focuses on the results obtained by comparing the values of thermal diffusivity (κ), thermal conductivity (λ), and specific heat capacity (ρcp) measured at normal atmosphere and room pressure. The experiment was performed using the pulse transition method and all three basic thermophysical parameters were estimated from the measured temperature response to the heat pulse using a theoretical model derived for the cuboid geometry of the samples (cuboid model). The uncertainty of the estimated parameters using the Cuboid model is in the range of 1-3% depending onset of the experimental conditions and sample geometry. The model also includes the temperature of the heat exchangers and the influence of heat losses from the free surface of the sample to the surroundings in the lateral direction, which is represented by the heat transfer coefficient α. The thermophysical parameters obtained by the cuboid model using the Levenberg-Marquardt regression analysis applied to the thermal responses prove the prediction of a linear dependence with the bulk density of alder wood. [ABSTRACT FROM AUTHOR]

Heat exchanger is one of the key components for process-heat transfer application in industries. Heat transfer process is time variant, nonlinear and is subjected to disturbances due to fluid flow and reactions. To effectively control the entire process, intelligent and cognitive controllers are being employed due to their self-learning and adaptation properties. BELBIC is a bio-inspired process imitating the behaviour of limbic system of mammalian brain. In this paper a generalized approach for the formulation of BELBIC parameters is presented. The focus of the paper is on design of BELBIC and formulation of nonlinear emotional cues for process control, proposed emotional cues has high capability of adaptation, to improve the system performance in terms of transient and steady state performance. The steady state performance is improved by a factor of 10 with non-linear ECs. Performance measure of ISE is minimum with and without disturbances in the process of heat exchanger control, as compared to PID and existing controllers. [ABSTRACT FROM AUTHOR]

In this paper, performance investigation of solar power organic Rankine cycle (ORC) coupled with conventional compound parabolic collector have been done. The working fluid Butane/R1234yf is selected for ORC model. Moreover, thermal and exergetic efficiency has been evaluated by varying mass flow rate and solar beam radiation parameters. The modification has been done in ORC structure by incorporating internal heat exchanger. It has been concluded that the exergetic efficiency improved by 12.9% and exergy destruction reduced by 20.23% incorporation of internal heat exchanger. The proposed system may be effectively utilized in remote areas for electrification and fresh water production. [ABSTRACT FROM AUTHOR]

A recent method of energy test for refrigerator requires two temperature test condition and lower airspeed of the temperature chamber. The testing technology laboratory of the Indonesian Institute of Sciences has developed a temperature chamber capable of conducting the test. This paper presents the heat transfer characteristic of the proposed configuration for heat exchanger for temperature chamber design. An aligned and staggered configuration is investigated in the current study as the proposed configuration of the heat exchanger through numerical modelling. Three parameters of heat transfer characteristics are determined in this current paper: heat transfer rate, heat transfer coefficient, and pressure loss. The result shows that the staggered results in higher heat transfer rate and heat transfer coefficient. Such greater heat transfer values may occur since the greater amount of bank for staggered configuration, and thus provide a greater area for fluid behavior. The verification model indicates a far gap at around 75% relative to the theoretical determination. The growth rate of 1.1 in the mesh sizing is not enough to provide a small sizing that may be indicated as a factor to such a considerable gap. The implication of the greater heat transfer space in staggered configuration brings to the concern of energy consumption for fan-speed as a result of greater pressure loss. The energy need for fan speed for staggered configuration is 1.66% higher of aligned configuration. [ABSTRACT FROM AUTHOR]

High-temperature receivers are critical for third-generation (Gen3) Concentrating Solar Power (CSP) technology to achieve high system efficiencies, and play the role of converting concentrated sunlight into heat. In this paper, two CSP systems with different working fluids in the receiver are examined in order to achieve identical supply of heat to the power block: a direct high-temperature chloride salt system and an indirect high-temperature sodium receiver with an associated heat exchanger to heat the same chloride salt. The presented numerical model indicates that the indirect sodium-salt system has a 4.37% higher exergy efficiency than the direct chloride salt system. The exergy destruction in the added sodium-salt heat exchanger was only 0.54%, which did not outweigh the performance benefits gained from using a sodium receiver, when compared to the direct salt case with no heat exchanger. Even at lower DNIs, the better heat-transfer characteristics of the sodium are responsible for its improved performance compared to salt in the receivers. [ABSTRACT FROM AUTHOR]

This paper presents the method of effectiveness NTU for bayonet tube heat exchangers thermal analysis, with uniform conditions along the outer tube wall surface. Using bayonet tube control volume's energy balance, linear fluid temperatures differential equations and boundary conditions are derived at steady state conditions. The governing equations and boundary conditions are expressed in non-dimensional form. The temperature is found to be dependent on four parameters Hurd number (Hu), ratio of outer tube convective heat transfer coefficient(ξ,), number of transfer unit (NTU), and flow path. The method of fourth order Runge- Kutta was used for numerical integration of the coupled linear temperature differential equations and the results are presented graphically for selected values of Hu,ξ, NTU and flow path. The effectiveness is obtained to be dependent on NTU and fluid temperature at the shell side. It was observed from the tubes temperature distribution at a low Hu value, that little heat is exchanged within the tubes. Heat transfer to shell side fluid increases with an increase in ξ value. Maximum heat transfer is achieved by reverse flow path B. [ABSTRACT FROM AUTHOR]

Due to the excess use of air conditioning systems led to significantly increase the demand for electric power in the household sector. Therefore, to decrease energy consumption, it can use an Earth-Air Heat Exchanger (EAHE); it has been demonstrated to be promising method for heating and cooling applications. In this paper, simulation study was performed using ANSYS FLUENT 19.0 (CFD) program as a numerical analysis on the impact of different pipe shape and air velocity on the performance according to the climatic conditions of Baghdad-Iraq in the summer and winter seasons. The pipes shapes in EAHE system that were used are spiral, wave and straight at the same length and diameter, and it has been studied their impact on performance at different speeds (5, 10 and 15 m / s). The results of numerical analysis showed that the shape of pipes and velocity of inlet air have an effect for the temperature of outlet air and performance of EAHE. Through the results obtained, it was found that the shape of straight tube presents the best performance compared to the other two shapes of spiral and wave. Therefore, the better performance for EAHE can be achieved on operating the system at low air velocity together with straight shape for the exchanger pipe. [ABSTRACT FROM AUTHOR]

To improve the performance of an air-conditioning system (A/C) in sub-tropical climates This paper presents an experimental study by studying the double effect of indirect evaporative cooling integrated with heat pipe heat exchanger (HPHE) on sensible heat recovery as well as the coefficient of performance (COP). In this study, HPHE was used consisting of two rows of copper tubes with a diameter of 0.014 m, and length of the evaporator is 0.3 m, the condenser is 0.3 m and the adiabatic is 0.15 m. The results showed that the use of a heat pipe heat exchanger decrease the temperature of air inlet condenser of (A/C) system from (2-3) degree and improves the coefficient of performance by 10 % when compared to conventional cooling systems. HPHE filled with acetone with filling rate of 70%. [ABSTRACT FROM AUTHOR]

Heat exchangers are a common heat transfer mechanism used in a variety of applications ranging from home to industrial, aircraft, and vehicles. The aim of this research is to study the hydrothermal efficiency of a double pipe heat exchanger with helical fins on annular side of counter flow heat exchanger numerically and compare the results of a double tube with and without screw tape. The investigation begins by employing numerical modeling of helical tapes under different configurations, with different pitches (10, 15, and 20) mm and one height of 10 mm as passive heat transfer augmentation strategies, which are simulated using ANSYS 2022 R1 software. The findings reveal that the current work's numerical results and earlier research's experimental findings are in good accord. Furthermore, while using (Helical Tap Insert) (HTI), the thermal performance of the new typical is found to be better than the typical model. Furthermore, it was found that the Nusselt number achieves the highest growth when the pitch (p) is (20) mm and increases the pressure drop. Furthermore, it was discovered that when the pitch (p) is (20) mm and pressure drop is increased, the Nusselt number grows the most. Furthermore, as associated to the typical model, the total thermal effectiveness of heat exchanger for the new model has greater by 9.9%. This difference is due to the fact that in the theoretical study, ideal conditions are assumed. The experimental design, the assumptions, operating circumstances, and accuracy of the devices are taken into account. It was noted that the value of the specified percentage of hydrothermal improvement achieved the highest value in performance for the same case that was with spiral fin and pitch length (20) mm, which is 1.6% compared to the traditional model. [ABSTRACT FROM AUTHOR]

The performance of evaporative cooling systems depend strongly on the relative humidity of the inlet air. Therefore, it is crucial to reduce the inlet air humidity ratio, and one of the solutions to regulate this ratio is using desiccant material. In this paper, a practical study of an evaporative cooling system was conducted and a dehumidification unit was constructed that consists of a (fin-tube) heat exchanger covered with silica gel to overcome the sensible and latent load. The heat exchanger is connected with an evaporative cooling system and a heat recovery unit as an indirect cooling stage. The cold water in the evaporative basin is utilized for precooling the inlet air. Furthermore, using the cold water of the evaporative basin can reduce the heat released during the removal of moisture from the air (adsorption process). Hot water from a heat source (electrical heater) was used to regeneration the desiccant. The effects of the external conditions (temperatures and humidity) on the system performance were studied. In addition, the effect of inlet air velocity, hot water flow rate, and the time required to complete the cycle on the performance were evaluated. It was found that the desiccant material can be regenerated at a temperature between 45-65 °C and the supply air temperature to the zone of 25 °C when the airflow is 0.48 m3/s. The system can work in hot and humid places. [ABSTRACT FROM AUTHOR]

The experimental process carried out in this paper is to determine the convection heat transfer coefficient, overall heat transfer coefficient, and nanofluid heat transfer rate based on DWCNT (double-wall carbon nanotube) nanotubes applied to a shell and tube heat exchanger. The advantage of using DWCNT nanoparticles is the high thermal conductivity value. The volume fractions of nanoparticles were 0.1%, 0.3%, and 0.5% with the addition of PVP surfactant. Experimental tests were conducted to determine the heat transfer performance applied to a shell and tube type heat exchanger with upright baffles. This study aims to improve the heat transfer performance by utilizing nanofluids based on DWCNTs nanoparticles. As a result, using DWCNT nanofluids instead of base fluids increases the convective heat transfer coefficient values and overall heat transfer. The increase in the volume fraction of DWCNTs nanoparticles is also accompanied by an increase in the heat generated. The highest thermal conductivity was obtained by adding 0.5% volume of DWCNTs nanoparticles, which was 0.640 W/m.K. The highest heat transfer rate was produced by adding 0.5% volume fraction and 0.02% PVP with a result value of 70.191 W. [ABSTRACT FROM AUTHOR]

Heat is strongly related with the combustion process. This is due to the main purpose of the combustion process that converts the chemical energy content, in the fuel, into heat before it will further be converted into work energy. In order to reach sustainability in terms of operation and durability for the ICE, a thermal management system is applied using a heat exchanging device. In secondary flow enhancement technique, vortices are created intentionally to the main flow using vortex generators purposely to introduce and exploit the secondary flows. It was said that the associated pressure drop across the fin-and-tube heat exchanger is relatively low for the secondary flow enhancement technique as compared to the main flow enhancement technique. Therefore, in this paper, the discussions are made on one of the prospective methods to improve the performance of thermal management system, specifically on fin-and-tube heat exchanger, known as secondary flow enhancement technique using the vortex generator. [ABSTRACT FROM AUTHOR]

This paper reports experimental work on testing of cooling of electronic equipment using dual coolant technology in a novel apparatus that adopts natural convection cooling method with shell and tube type heat exchanger in evaporator and plate and tube heat-exchanger in the condenser. The system has a cooling capacity of 96 W over a heater with a 9 cm2 surface area. The equivalent heat flux is 23353.84 w c m 2 . This is an innovative technology for energy-efficient electronic equipment cooling. The result of experimental studies with various combinations of primary and secondary coolants with constant heat flux as inlet boundary condition were also found and presented in the results section. This technology utilizes properties of fluid and transfers the heat from the walls of electronic devices to the condenser using natural convection. [ABSTRACT FROM AUTHOR]

The experimental process is carried out in this paper to determine the value of the convection heat transfer coefficient, overall heat transfer coefficient, and the rate of heat transfer for nanofluids based on DWCNTs (double-wall carbon nanotubes) nanoparticles which ar e applied to shell and tube heat exchangers. The advantage of using DWCNTs nanoparticles is the high thermal conductivity value. The volume fractions of nanoparticles were 0.1%, 0.3%, and 0.5%. Tests were carried out to determine the heat transfer performance applied to the shell and tube type of baffle and no-baffle heat exchanger tools. The purpose of this research is to improve the heat transfer performance by utilizing nanofluids based on DWCNT nanoparticles. The results show an increase in the value of the convection heat transfer coefficient and the overall heat transfer coefficient when using DWCNTs nanofluids rather than using base fluids. [ABSTRACT FROM AUTHOR]

Based on the analysis using the developed methods of calculation and numerical simulation of heat transfer processes in the tanks of ground-based complexes with integrated heat exchangers, the paper presents the results of research on improving the efficiency of the cooling processes of rocket fuel components (CRT) when using liquid nitrogen for cooling the CRT, which is bubbling liquid coolant in the heat exchanger built into the tank. [ABSTRACT FROM AUTHOR]

The paper shows that during the processing of plastic waste into liquid fuel, up to 10 m3 of gases and vapors are formed, which, at the moment, are considered to be spent coolant. At the same time, the echo temperature can reach 130-250°C. That is, these gases and vapors can be recognized as a secondary energy resource of thermal generators. To use this secondary thermal potential, a heat exchanger design is proposed for operation in a device with an organized flue gas emission and vapor condensation. The regression dependence of the resulting temperature of the heated coolant is obtained, as well as graphs for determining its full-scale values, which showed the high efficiency of this solution. It is proved that the use of this technology will reduce the level of fuel consumption at operational facilities. [ABSTRACT FROM AUTHOR]

The microchannel is the need of twenty first century. It plays significant role in electro-mechanical systems. The higher the heat transfers from the system higher the effectiveness. They are reliable cooling devices because they can carry high amount of heat energy. In this paper the various parameters are analysed such as pressure drop, flow visualisation, and heat transfer as well as friction factor is also studied. The characteristics of the microchannel heat exchanger are considered under various geometrical parameter, different material, different hydraulic diameter and different working fluid. The pattern of bubble formation inside the channel have been studied which is essential for measured the heat transfer and pressure drop inside the channel. A comparative relation between conventional theories and experimental setup is done to understand the phenomenon of the friction factor. The result shows the effective change in heat transfer characteristics and validate with the microchannel heat exchanger. The relation between friction factor and Reynolds number provides the understanding of Reynolds number in the heat exchanger with different type of fluid flow. The validity of conventional channel is also studied under different conditions. Overall this review provides basic understanding of microchannel heat exchanger. [ABSTRACT FROM AUTHOR]

The flow behavior of the liquid film has a significant impact on the efficiency of heat and mass transfer in falling film type heat exchangers. It is essential to study the distribution of film thickness around the tubes. This paper presents a numerical investigation of falling-film over inline horizontal tubes. The objective of this study is to compare the film thickness under different liquid distributor sizes. The simulations are carried out with two inline horizontal tubes using ANSYS Fluent. The Volume of Fluid (VOF) technique is implemented in this analysis to identify the interface between the two phases. The spreading of the falling film over the inline horizontal tubes at different liquid distributors namely Dist1, Dist2, Dist3, Dist4, and Dist5 was observed. Results illustrated that flow patterns near the upper and lower stagnation zones of the horizontal tubes were shaped by the liquid distribution conditions. It is found that film thickness is affected by the size of the distributor. The results showed that the film thickness increases with the increasing size of the distributor. The present work helps as a reference to eliminate flooding and low wetting phenomena over the heat exchanger tubes. [ABSTRACT FROM AUTHOR]

Ejectors can provide advantage over conventional expansion device, in terms of energy as well as exergy, especially in high pressure transcritical R744 refrigeration systems. This paper presents a simulation-based comparative study of annual energy consumption and environmental impact of four different configurations of ejector expansion R744 systems for thirty different cities in India, spread across five different climatic zones. A control strategy is also adopted in order to ensure smooth transition of operation between subcritical, transcritical and transition modes for round the clock operation. A configuration having multi-compression ejector expansion system equipped with internal heat exchanger (MCEETRC+IHX) along with suggested control strategy exhibited lowest annual energy consumption. However, all the components are not equally effective for all the cities or weather conditions. Ambient temperature and evaporator temperature are found to play an important role. A simplified economic analysis is also presented which suggests overall cost-effectiveness for supermarket food storage application. [ABSTRACT FROM AUTHOR]

Energy is needed to run almost everything we see around us, from cars to the electricity power generation plants and everything else. Fossil fuels produce harmful products on combustion. One such eco-friendly alternative is Di-Methyl Ether also known as DME. In this study, a DME plant of capacity 160 tons per day was designed. Methanol dehydration process has been adapted as the process of production. The purity of DME from this plant is 99.5% by weight. Distillation column T-202 and heat exchanger E-208 were designed in detail. The detail design results showed that T-202 needed 6 stages for separation and a column diameter of 1.28m, while the simulation results showed 7 stages and column diameter as 1.285m for the same separation process. Furthermore, E-208 is of type 1-2 shell & tube heat exchanger with 307 tubes and tube length of 5.5m, however the Aspen EDR simulation results were also in close agreement with 304 tubes and 5m length for the same heat exchanger. This paper presents the results of simulation results of the simulation of these equipment's and full plant done using Aspen plus V8.8 software and Aspen EDR. [ABSTRACT FROM AUTHOR]

Polymeric hollow fiber heat exchangers were first proposed in 2004 by New Jersey Institute of Technology as an alternative to metal exchangers for low temperature application. The first study of this type of heat transfer surface started at Brno University of Technology in 2008. This paper presents a brief survey of activities of Heat Transfer and Fluid Flow Laboratory in the field. The heat exchangers presented use a polymeric capillary with an outer diameter of 0.5mm – 1.3mm and a wall thickness of about 10% of the outer diameter. The typical material is polypropylene and this material was used in the initial years of development. Tiny polypropylene fibers can withstand a burst pressure of 50 bar at room temperature. Heat exchangers using hollow fibers can in principle either have a rigid structure or be a bundle with a chaotic structure. These heat exchangers are effective even in natural convection application where the advantage of high heat transfer coefficient on micro surfaces is utilized. The use of plastic and non-corrosive materials is advantageous in applications where the weight of the heat exchanger is important (about 50% reduction in weight in comparison to classical metal products) and in difficult chemical environments. Flexible polymeric hollow fiber heat exchangers were developed and prototypes were prepared and tested for liquid / air and liquid / liquid conditions. The paper presents a survey of the materials used for hollow fibers, a description of the production of fibers by extrusion, the basic physical principles of heat transfer on micro-surfaces, and prototyping of the number of heat exchangers both with rigid and chaotic structures. [ABSTRACT FROM AUTHOR]

Electronic is a significant device in our daily life. To ensure its good performance, the temperature of chips must not exceed 80°C. For a long time, Computational Fluid Dynamic (CFD) has been a powerful tool to analyze fluid flow, heat exchangers, and other equipment that have been applied widely in industry. In this paper, the authors designed the electronic enclosure and used CFD Autodesk to analyze its thermal performance. The three types of electronic enclosures are a/ the enclosure without any ventilation slot; b/ the enclosure with both ventilation slots on the top and the bottom of it; c/ the enclosure with both ventilation slots on the left and right of it. The 2 same power small chips and the large chip whose power were 0.5W and 2W, respectively, were used as the heat source. Moreover, the effect of the radiation heat transfer of the surface enclosure was also analyzed. The result shows that the enclosure which has both ventilation slots on the top and bottom has more efficiency than others. Also, the radiation heat transfer plays a vital role in enclosure cooling without the fan. For that reason, covering the white coating with emissivity ε=0.9 or the black coating with emissivity ε=0.98 is an excellent way to decline the temperature of the enclosure by radiation heat transfer. [ABSTRACT FROM AUTHOR]

This paper offers a case study enabling the performance evaluation of the Al-khairat power plant in Karbala city based on the application of the Pinch Analysis (PA) method to determine the best possible heat recovery (Qrec.) available in the plant and how can this be used to minimise energy consumption and save energy. PA has been used to study integration in several processes to help develop optimum heat transfer and minimise total cost: such work has also allowed the development of a Heat Exchanger Network (HEN) design to support this process. Al-khairat power plant consists of 10 units, each of which generates 125 MW; thus, the overall production of the plant is 1,250 MW. Unit 3 was selected as a representative unit for this study, based on its performance stability throughout the year. The data from control room facilities was then used to theoretically calculate the relevant heat loads (ΔH), which were applied in a Composite Curve (CC) to evaluate the Qrec. However, the results suggested that PA may not be effectively applied in this power plant, with similar conclusions being obtained from the application of simulation software (Aspen Energy Analyzer, AEA). [ABSTRACT FROM AUTHOR]

Heat exchangers make up a large group of heat-power equipment, so the right choice of heat exchangers is an important task. In this paper, a numerical experiment was carried out with the created models of plate water heat exchangers with different plate shapes in the ANSYS Workbench software package. Boundary conditions were formulated for all four types of plate heat exchanger, which, as a result of calculating and processing the results obtained, revealed the values of temperature and pressure at the outlet of the heat exchanger channels. Based on these data, the local resistance coefficients ζ and the temperature efficiency Et were calculated for each heat exchanger model, and the influence of the plate shape on the increase in temperature efficiency and on the increase in pressure losses was also determined. [ABSTRACT FROM AUTHOR]

The PHYSOR project conducted by ALTRAN TECHNOLOGY is part of the research and development theme of new small modular reactor SMR concepts. An innovative project aims to improve the performance, design and safety of an SMR installation by integrating new technologies. In the SMR facilities, the steam generator (SG) plays an important role in the transmission of energy between the primary circuit and the secondary circuit of the reactor. For this, we have interested in this work to study the thermo-hydraulic behavior of steam generator. The aim of this paper is to develop a numerical model to simulate the heat exchange within the SG. The approach used in these numerical tools varies considerably according to the required accuracy. This paper gives a short overview of the early development of a tool that aims to describe the thermal and fluidic behavior of heat exchanger. The modelling approach is based on an averaged resolution of the Navier-Stokes equations using a coupling method between the primary and the secondary circuits. The results concerning temperature contours and velocity profiles for the two circuits were studied for different cases. The method used features a suitable compromise between results accuracy and time consuming numerical simulation. [ABSTRACT FROM AUTHOR]

This paper reviews progress in microwave thermal rocket research since the concept was set forth in this forum 4 years ago. Since then, a microwave thermal thruster has been demonstrated in the laboratory for the first time, albeit at small scale. A numerical model has been developed that captures the behavior of this configuration and can be used to design future experiments, and system point designs have affirmed that a specific impulse of greater than 700 seconds and thrust to weight ratio of greater than 70 is quite possible. In future work, it remains to fully explore the wider design space and relative merits of microwave thermal rockets, delineating the operating regime in which microwave thermal rockets are superior to alternative approaches. [ABSTRACT FROM AUTHOR]

In this paper, design graphs, tables, and equations relating to performance of counter cross-flow heat exchanger were developed. Equations derived previously to study the temperatures at intermediary passes and at the discharge were solved by means of MATLAB. The results from the MATLAB were used to generate graphs. Design graphs describe the functioning of the heat exchanger in terms of key dimensionless factors. These factors are heat exchanger effectiveness, capacity-rate ratio and number of transfer units. Design graphs aid engineers in choosing proper NTU and capacity-rate ratio for the heat exchanger. Likewise, correction factors were established to serve incompletely mixed conditions in the heat exchanger. [ABSTRACT FROM AUTHOR]

The paper shows that when burning 1 kg of fuel, 4-10 m3 of flue gases are formed, which are currently recognized as spent coolant, and are released into the atmosphere. At the same time, their temperature can reach 250°C That is, these flue gases can be recognized as a secondary energy resource of thermal power plants with high potential. The design of a recuperative heat exchanger for working in a chimney with organized flue gas emission is proposed. The regression dependence of the resulting temperature of the heated coolant is obtained, as well as graphs for determining its full-scale values, which showed the high efficiency of this heat exchanger. It is proved that the use of this technology will reduce the level of fuel consumption at operating facilities. [ABSTRACT FROM AUTHOR]

In this paper numerical investigation by ABAQUS software of heat conduction processes in the fins of two-stage "water to air" heat exchange (HEx) apparatus. Temperature values of the processes in ducts, have been used as boundary conditions for accomplishment of the simulations in the heat exchanger's fins. The coefficients of heat convection for the processes between the fins and the airflow calculated by temperature field in the fins. Processes have been studied in "cooling" and "heating" regimes. The values of the coefficients obtained on the basis of simulations and by criterion equations, are compared. [ABSTRACT FROM AUTHOR]

HTGR is an advanced gas reactor that utilized high temperature and high pressure. This paper investigated five different working gas in four Brayton cycle configurations in HTGR 10MWth. Thermodynamic analysis using gas-cold standard assumption were applied to measure the efficiencies. This paper also considered temperature interaction in heat exchangers and capability turbine to drive compressor. Particular gas would be suitable for particular pressure ratio and diagram. 1T2C diagram with pressure ratio 9 and carbon dioxide as the working gas were able to reach optimum thermal efficiency, were about 52 %. [ABSTRACT FROM AUTHOR]

The paper presents an extensive modeling activity for optimum design of the Heat Recovery Vapor Generator, HRVG, in an ORC-based unit, bottoming a solar thermal collector for domestic hot water production. Sliding vanes rotary machines-equipped ORC units are widely acknowledged among the most suitable options for low grade (100-120°C source temperature) heat recovery, due to their technological advantages (low cost, low maintenance) and higher energy merit (flexibility and applicability to a variety of upper thermal sources). In such plants, the energy performance boost calls for the exergy losses reduction at the heat recovery vapor generator, via the improved matching of the heat exchange curves. The paper investigates the potential gain on exergy and energy efficiency of two different techniques, i.e. the evaporation split over two pressure levels for pure R245fa and the use of R245fa/R227ea zeotropic mixtures, as the working fluid. Optimum evaporation pressures, pinch point temperature difference, mass flowrates and superheating degree on both loops are selected for each case study and the system energy performance assessed, hence providing a reliable criterion for optimum design of small-scale plants. [ABSTRACT FROM AUTHOR]

In this paper performance investigation of shell and helical tube (volute pipe) type heat exchanger (interchanger) is presented. In this analysis different parameters affecting performance of heat interchanger such as fluid temperatures, overall heat flow coefficient, flow rate of fluid, heat flow rate, thermal conductivity, thermal efficiency, tube diameter, tube length, thickness of tube, effectiveness etc. are taken into considerations. The effect of change in flow rate on other performance parameters is studied for same geometrical configuration. The rate of mass flow of warm and cold fluid is varied between 1 LPM and 2 LPM and results are presented. As the mass moving rate of both fluid escalate the overall heat flow coefficient and actual heat flow coefficient value also rises. The Heat interchanger effectiveness is adversely altered by mass flow rate of both warm and cold fluid. The escalation in rate of mass flow lowers down the effectiveness approximately up to 16%. The experimental value of effectiveness of heat interchanger is less than one. All the experimental results have been validated based on value of heat interchanger effectiveness. The NTU value is also affected by rate of mass flow of warm and cold fluid. As rate of mass flow increases, the corresponding value of NTU deteriorates. The specific heat of warm fluid is greater than cold fluid. [ABSTRACT FROM AUTHOR]

A heat exchanger is used in different applications like cooling or heating of a fluid stream of single or multi component fluid streams. Air-conditioning, chemical plants, petrochemical plants etc. It is utilized to move thermal energy (enthalpy) between minimum of two fluids, between a solid body and a fluid, at numerous temperatures in heat interaction. There are typically no external heat and work connections. Heat transfer should be possible in sequences of action in fluids, liquid to gas. Heat exchangers are used to reheat a cold fluid, cool a hot fluid, or combine the two. In this paper design the spiral plate heat exchanger and tested with fluid is water and MATLAB code is written for spiral plate heat exchanger according to our design point of view and compare different fluids i.e water and unused engine oil and graph is generated for effectiveness Vs Mass flow rate of cold fluid. [ABSTRACT FROM AUTHOR]

The aim of this paper is thermal analysis of model water to water heat exchanger at different mass flow rates. Experimental study deals with determination of total heat transfer - power of the heat exchanger. Furthermore the paper deals with analysis of heat exchanger charakcteristic using a definition of thermal efficiency. It is demonstrated that it is advisable to monitor the dependence of thermal efficiency and flow ratio. [ABSTRACT FROM AUTHOR]

This paper presents results of an exploratory study aimed to investigate heat loss during charging the thermal energy storage (TES) bin with hot solid particles. Tests were performed at the pilot particle-based power tower plant in King Saud University in Riyadh, Saudi Arabia. In this plant, a small TES bin is installed between the particle heating receiver and the particle-to-working-fluid heat exchanger. Two types of experiments, the on-sun test and the steady-state test, were conducted; in each experiment, two cases were considered, namely the empty bin and full bin. Results show that in the case of empty TES bin, the air, entrained as a result of particles falling, can cause a significant temperature drop in the particle side. Moreover, the use of several particle-feeding lines can promote the so-called chimney effect. In the case of full bin, the amount of entrained air was reduced significantly, thus the temperature drop in the particle side was shrunk greatly. However, results also show that the air occupying the empty region (due to the particle's angle of repose) inside the full bin recorded lower temperature than that of particles which implies that the chimney effect is still present. [ABSTRACT FROM AUTHOR]

Solar Thermal Power Plants (STPPs), based on supercritical CO2 (sCO2) cycles, seem to be a promising alternative to increase the global solar-to-electric efficiency. The most conventional scheme for this technology is a molten salt (MS) central receiver, working at high temperature (above 700°C), coupled to the sCO2 cycle. For this scheme it is proposed a new design of the source heat exchanger that transfers the thermal energy from the molten salt to the CO2: the Compact Honeycomb Heat Exchanger (CHHE), in which the molten salt goes through a larger circular duct that is surrounded by 6 smaller trapezoidal ducts, through which the sCO2 circulates. This paper is focused in the thermal model of this new heat exchanger, and a thermo- economic optimization for a selected supercritical STPP. [ABSTRACT FROM AUTHOR]

In order to maintain viability as a future power-generating technology, concentrating solar power (CSP) must reduce its levelized cost of electricity (LCOE). One component of solving this problem is reducing the cost of the power block while simultaneously increasing the efficiency of the thermodynamic cycle. One disruptive technology that has the promise to accomplish this is supercritical CO2 (sCO2) based power cycles. These cycles are conceptually similar to steam cycles; however, they have substantially smaller turbomachinery at equivalent power while also delivering more efficiency at turbine inlet temperatures of 500-700°C. Previous work has thoroughly investigated the sCO2 turbomachinery design and its impact on power cycle performance and LCOE. However, the precooler (upstream of the first stage compressor) has received significantly less attention. The pr-cooler design is not trivial because minimizing the compressor inlet temperature and temperature variation are critical to cycle performance. Compressor performance and cycle efficiency vary significantly with low-side temperature. Also, operating with a compressor inlet temperature away from the design point (above or below) significantly degrades cycle efficiency. Because CSP plants are generally planned for installation in remote, arid areas where water is scarce, dry cooling is required. The current state-of-the-art dry cooling technology consist of large bays of finned tubes, cooled by fan-driven air in cross flow. The fan-driven air allows for low power consumption and low operating cost. However, the cross-flow configuration results in low thermal effectiveness and maldistribution of air throughout the tube banks. This requires the interface area between streams to be very large, meaning very large installations incurring large capital cost. It has been found that improvements to the dry cooler technology can further reduce the power block contribution to LCOE. This study investigated the impact of the precooler on the LCOE for a CSP facility utilizing a sCO2 recompression Brayton cycle. This paper presents the high-level sensitivity studies used to determine the best path forward for reducing the precooler's contribution to LCOE. The sensitivity study included investigation of the cooler performance (approach temperature), CO2-side pressure drop, air-side pressure drop, air-supply power consumption, and cooler system capital cost. Results of the study show that utilizing a dry cooler with a high effectiveness (achieved at higher heat exchanger capital cost) and low air-side power consumption levels produced the lowest LCOE contribution. Applying more advanced heat exchanger technologies will be required to reach the higher heat transfer effectiveness values, while maintaining reasonable capital cost values. [ABSTRACT FROM AUTHOR]

The Generation 3 Concentrating Solar Power Liquid Pathway (G3LP) proposes the use of a ternary chloride molten salt as a heat transfer fluid and thermal energy storage (TES) media with heat input from a sodium receiver loop and heat removal by a supercritical carbon dioxide (sCO2) Brayton cycle to reduce the levelized cost of energy of commercial CSP plants to 6 ¢/kW-hr in line with the U.S. Department of Energy SunShot targets. This system architecture requires a primary heat exchanger (PHX) between the ternary chloride salt TES and the sCO2 working fluid of the power cycle operating up to 720 °C with a 30-year lifetime, high reliability, and low cost. The combination of a highly corrosive high-temperature fluid on one side and a high pressure and temperature fluid on the other suggests the need for a compact high-performance heat exchanger in order to reduce the amount of corrosion-resistant material required for fabrication and allow for small channel diameters to more easily contain the operating pressure of the sCO2 at high temperatures (>700C). This paper presents the results of the G3LP design for a compact salt to sCO2 heat exchanger scalable to a 200 MWth commercial plant size with a 1 MWth detailed design for demonstration with a G3LP Phase 3 pilot plant. [ABSTRACT FROM AUTHOR]

Design and construction of a particle-to-sCO2 heat exchanger test station is described in this paper. The purpose of this test station is to make steady-state measurements of thermal performance with sCO2 as the working fluid. While the test station was initially constructed to test a 20 kW heat exchanger developed under the Gen3 Particle pilot plant (G3P3) project, it also was designed to accommodate testing of other heat exchanger configurations. Improvements for this test station design is based on lessons learned from prior heat exchanger testing. Maximum pressure and temperature ratings are based on the desire to use primarily stainless steel in the construction to reduce cost and lead time of components. Construction of the test station was completed and commissioning and initial testing took place during the October to November 2020 timeframe. [ABSTRACT FROM AUTHOR]

In this paper energy and exergy analysis on components of working rectified sprite plant of capacity 11 TPH coal and the gas-fired boiler is carried out. Most of the system Is design on energetic performance criterion and is not sufficient for finding system imperfections. Hence exergy analysis is necessary to improve. It has been observed that Energetic and Exergetic performance of Plate Heat Exchanger use for heating the feed water for the boiler can be optimized. Heat carried away by Spent wash which is waste product of the plant and used as hot fluid in PHE can be utilized more effectively. Analytical calculation is carryout in Excel program to study the change in mass flow effect and by graph it has been observed that by increasing the flow rate of spent wash or decreasing the flow rate of feed water there is an increase in energetic efficiency, exergetic efficiency, and feed water temperature. Also, the effect of adding a gasketed plate has been observed, temperature increase by adding plate but there is also a pressure drop. The experimental is carried out based on analytical result there is an increase in exergetic efficiency of PHE by 6 to 7 % and increases in temperature of feed water 0.90-degree c by increasing the mass flow by 900 kg/hr. Also, other components of the boiler were observed before and after experimentation and found to be increased in performance. The thermal performance of PHE is optimized by adjusting the mass flow rate. [ABSTRACT FROM AUTHOR]

Staged crushing of kimberlites are planned to introduced at the enterprises of JSC ALROSA to prepare the ore for enrichment. For such manufacturing schemes, there are risks of freezing of crushed ore during emergency shutdowns of equipment. To assess these risks, a thermodynamic calculation method is being developed in this paper. A physical model has been developed, according to which heat exchange occurs only through the surface of ore pieces. Mathematical model is developed on the basis of the proposed physical model and contains system of differential equations with respect to the ore and the environment temperatures depending on time with the initial conditions. Computational implementation of the developed model is accomplished. The model parameters are adapted from the experimental data. The developed model can be used to evaluate the parameters of congelation of wet and frozen ore pieces to each other and parameters of freezing of ore to the wall of the plants at various ambient temperatures. [ABSTRACT FROM AUTHOR]

A novel heat transfer loop for thermoacoustic-Stirling engines which could substitute for a traditional heat exchanger was developed. This new heat transfer loop uses a pair of check valves to transform oscillating flow into steady flow that allows the oscillating flow system’s own working gas to go through a physically remote high-temperature or cold-temperature heat source. Since the early principle experiment has achieved success, this paper explores the real operating performance of this heat transfer loop by coupling with thermoacoustic-Stirling engine. Furthermore, a new type water-cooled heat exchanger was developed in this paper to deduce the extra acoustic power dissipation. In addition, the influence of two kinds of check valves the heat transfer loop was discussed in this paper. The loop with 0.1 mm valve disc thickness shows that the heat transfer capacity is higher than the traditional heat exchanger. Our experiments have demonstrated its feasibility and flexibility for practical applications. [ABSTRACT FROM AUTHOR]

The paper deals with the predictive control applied to flexible cogeneration energy system FES. FES was designed and developed by the VITKOVICE POWER ENGINEERING joint-stock company and represents a new solution of decentralized cogeneration energy sources. In FES, the heating medium is flue gas generated by combustion of a solid fuel. The heated medium is power gas, which is a gas mixture of air and water steam. Power gas is superheated in the main heat exchanger and led to gas turbines. To protect the main heat exchanger against damage by overheating, the novel predictive protective control based on the mathematical model of exchanger was developed. The paper describes the principle, the design and the simulation of the predictive protective method applied to main heat exchanger of FES. [ABSTRACT FROM AUTHOR]