Type Heat Exchanger Research Articles

Investigation of novel type of cylindrical lithium-ion battery heat exchangers based on topology optimization

The in-depth research on the heat exchanger for lithium-ion batteries is of significant importance due to its crucial role in ensuring the safe operation of electric vehicle (EV) power systems. To enhance the thermal and flow characteristic of the heat exchangers, the novel heat exchangers for 18650-cylinderical lithium-ion batteries have been proposed by topology optimization with the minimization of pressure drop and the lowest average temperature (∏1) and the minimization of pressure drop and the lowest temperature difference (∏2) as two different optimal goals. The topology optimization based on the variable density method is utilized to get two-dimensional (2D) optimal channels, and then the optimized results are extended to three-dimensional (3D) heat exchangers. The 3D heat exchangers are named TOHE-1 which is gotten by stretching the topology channels with ∏1 as optimal goal and TOHE-2 which is gotten by that with ∏2 as optimal goal. Subsequently, a detailed thermodynamic analysis is performed to assess the effect of the type of heat exchangers, channel heights, weight factor of topology optimization function, mass flow rates and discharge rates on the cooling effect of the batteries. The results show that compared with the traditional channel heat exchangers, the heat transfer coefficient of topological heat exchangers have increased by 49.92%, while reducing pressure drop by 27.81%. Meanwhile, compared to TOHE-1, heat transfer coefficient of TOHE-2 is increased by 9.70%, while pressure drop is saved by 4.70%. Other studies have indicated that for a 4 C discharge of the battery, a topological heat exchanger with a channel height of 1.5 mm, a thermal performance weight factor of 0.1, and a mass flow with 3.3 × 10−3 kg s−1 is the optimum heat dissipation scheme. Finally, the numerical studies are verified by conducting the convective heat transfer experimental tests.

Simulation of heat and pressure transfer in concentric heat exchangers for small industrial scale

Abstract A Heat exchanger is a tool in industry which aims to transfer energy from hot fluid to cold fluid. The amount of heat transferred is an important parameter of the design and performance of heat exchangers. Concentric tube is a type of heat exchanger that is widely used in industries such as material processing and food preparation. One way to get the value of heat transfered before manufacturing a heat exchanger is to carry out computational fluid dynamic simulations. This simulation will make it easier for us to understand the heat transfer phenomenon that occurs from hot fluid to cold fluid. The aim of this study is to calculate how much heat transfer and pressure drop there is in a laboratory scale cocentric tube type heat exchanger. We also get a picture of the pressure drop that occurs due to fluid friction with the inner pipe walls. Experiments and simulations carried out in this study will then be validated. Variations in flow rate on the tube and shell sides are applied. the greater the flow rate, the greater the transfer of heat. The same trend is shown by variations in pressure. The greater the pressure, the greater the pressure drop that occurs. In this study, the pressure drop from the heat exchanger inlet to the heat exchanger outlet was 0.015%.

Numerical investigation of the influence of the heat exchange structure on the gas-liquid dispersion in a large-scale fermenter

A combination of computational fluid dynamics (CFD) and population balance model (PBM) was used to study the gas-liquid mixing conditions in a fermenter. The effects of the heat exchange structure on the flow structure, gas holdup, agitator power, bubble size distribution and interfacial area were investigated by numerical simulations. The simulation results showed that radial gas dispersion and liquid penetration are strongly hindered by the spiral heat exchanger, as there is no gap between the annular tubes at the circumference. An unstable flow structure, gas accumulation around the shaft and gas leakage, as well as large bubbles around the heat exchange tubes are due to the poor gas distribution. By increasing the spacing of heat exchange tube bundles in circumferential, the gas-liquid mixing in the fermenter is gradually improved with the uniform row heat exchanger, the compact row heat exchanger and the bundle type heat exchanger. The bundle heat exchanger acts as a baffle to suppress the large bubbles and effectively reduce the bubbles sizes and promote gas dispersion, which exhibits the maximum interfacial area and interfacial area per unit power. Compared to the fermenter with a spiral heat exchanger, the interfacial area and interfacial area per unit power of the fermenter with a bundle heat exchanger increase by 36.5 % and 9.1 %, respectively.

Optimization of Nanofluid Concentration for Energy Intensification in Corrugated Plate Type Heat Exchanger

The overall heat transfer coefficient of the heat exchanger will improve with an increase in the flow rate and concentration of nanofluid. But beyond an optimum nanoparticle concentration, the overall effectiveness seems to decrease due to an increase in pressure drop that consequently leads to an increase in pumping power. The novelty of the present work is to find the optimum concentration of CuO-Water nanofluid that exhibits the optimum heat transfer rate and global minimum pumping power, using both experimental and numerical study. The cold nanofluid and hot water entered the counter currently at 303.15 and 333.15 K respectively in the corrugated plate heat exchanger. It was observed from the experimental and numerical results that the values of overall heat transfer coefficient and pressure drop were increased monotonically (454–710 W/(m2-K) and 6–133 Pa respectively), with the increment in the concentration and flow rates of the nanofluid. Because of this trend, it was challenging to figure out the optimum nanofluid concentration using these parameters. Later, a procedure was presented to obtain an optimum concentration of nanofluid, to reduce the hot stream temperature by 288.15 K. The hydraulic power exhibited a global minimum at an optimum concentration of 0.5 vol% of nanofluid.

Numerical study flow and heat transfer characteristics of superhydrophobic single tube bundle surface and wake flow

Regarding the design optimization of the heat exchanger, the traditional method of changing the size of the macroscopic structure can no longer meet the increasing demand for heat exchange performance. The superhydrophobic surface can significantly reduce the flow resistance, which is expected to be a new method for the optimal design of heat exchanger. However, when the superhydrophobic effect is applied to a specific type of heat exchanger, its flow and heat transfer performance is not clear. In this paper, the flow and heat transfer model of the traversing superhydrophobic tube bundle is studied. Combined with the FLUENT 18.0 software, the slip boundary conditions of the superhydrophobic surface are deduced, and the flow and heat transfer characteristics of the superhydrophobic tube bundle surface and the wake are numerically analyzed, the influence mechanisms of slip effect on flow and heat transfer characteristics were obtained. Overall, as Ls increases, the comprehensive Nu, also known as heat transfer performance, on the cylindrical surface gradually increases, while the comprehensive Cf, also known as frictional resistance, on the cylindrical surface gradually decreases, indicating that superhydrophobic performance is expected to achieve heat transfer enhancement. The above conclusions can provide a theoretical basis for the optimal design of high-efficiency compact heat exchanger, and have important engineering application significance.

THE IMPACT OF HEAT-EXCHANGERS SURFACE FOULING AND THE POSSIBILITIES OF THEIR CLEANING

Introduction: This study investigates the real-world effects of pollutants on ship heat exchangers in the marine sector, focusing on the complex issues influencing maintenance expenses, environmental sustainability, and operational effectiveness. The core of the issue is figuring out a long-term, practical way to lessen the damage that heat-exchangers surface heat-exchangers surface fouling causes to ship heat exchangers. Purpose. The article aims to investigate and evaluate how pollutants affect ship heat exchangers in the marine sector from a practical standpoint. It seeks to shed light on how pollutants, such as chemicals, debris, and oil residues, impact a vessel’s environmental sustainability, maintenance costs, and operational effectiveness. The essay analyzes the complex issues caused by surface fouling-induced damage, highlighting the dangers of decreased thermal conductivity, greater overheating, higher maintenance costs, longer downtime, and possible environmental effects. Result. One practical consequence of pollutant-induced damage is that it calls for substantial and frequent cleaning, repairs, and maybe replacements of the heat exchanger components, which raises maintenance costs. Traditional cleaning procedures involve prolonged downtime for manual intervention, which worsens the economic effects on shipping businesses and trade routes. Furthermore, the study highlights the negative effects uncontrolled pollutants have on the environment, highlighting how crucial regulatory compliance is to avoiding legal ramifications and preserving the good name of the sector. Conclusion. In conclusion, preserving marine operational effectiveness and environmental sustainability requires reducing the impact of pollutants on ship heat exchangers. The selection of particular heat exchanger types requires customized cleaning techniques. Advanced solutions are provided by ecologically safe chemical agents, high-pressure water jets, and automated robotic systems. To avoid losing efficiency, regular cleaning must be done under the direction of real-time monitoring. Maintaining heat exchanger performance and guaranteeing the lifespan of ship power plants in the face of changing surface fouling concerns requires striking a compromise between operational needs, environmental responsibility, and proactive maintenance.

A novel oscillatory thermal response test method for efficient characterization of ground thermal properties: Methodology and data analysis

This study presents a novel thermal response testing (TRT) approach to minimize test duration, labor, and associated costs. The proposed method, Oscillatory Thermal Response Test (OTRT), employs an oscillating heat flux using a sinusoidal wave with specific frequency and amplitude characteristics. A custom-designed TRT apparatus was developed to regulate the heating injection pattern for precise control. In Sapporo City, Hokkaido Prefecture, and Kai City, Yamanashi Prefecture, Japan, two in-situ OTRTs were conducted. The temperature profiles of the fluid and undisturbed soil were measured through optical fiber cables integrated within the U-tube legs. A novel analytical method was devised to filter, smooth, and fit the recorded data, enabling the determination of the response temperature amplitudes at the borehole inlet and outlet. Also, the temperature time derivative method calculates the effective thermal conductivity in the early 3 h. Comparative analysis with Normal Thermal Response Tests (NTRTs) demonstrated the accuracy and validity of the OTRT approach. Significant conclusions from this study include a remarkable reduction in TRT duration by over 95 %, with a high accuracy of 92 % achieved using only the first 3 h of testing. The proposed method exhibited a Root Mean Square Error (RMSE) of 0.1 W/(m·K) compared to NTRTs. To establish a strong correlation between the Amplitude Ratio and Effective Thermal Conductivity, further experimental studies are essential to address the limitations of the current study. These studies should explore a variety of geological and hydrological conditions, borehole diameters, type of heat exchanger, diameter of U-tubem grouting material, combined with numerical analysis, to enhance our understanding of this relationship.

Performance Analysis of a Compact Offset Strip Fin Heat Exchanger for Lubrication System in Aero Engine

Abstract As a typical fuel-oil heat exchanger, an offset strip fin heat exchanger (OSFHX) can ensure the efficient and stable operation of the aero engine lubrication system. The paper establishes 20 kinds of numerical models of OSFHX that are verified by experiments. The effects of different structural parameters on the performance of lubricating oil in OSFHX were systematically studied. Based on dimensional analysis, the prediction model which can describe the overall performance of the OSFHX is obtained. The results show that with the decrease of fin distance (s), fin length (l), fin height (h), fin thickness (t), and fin shape angle (α), the heat transfer performance of the OSFHX is enhanced and the resistance is increased. With the decrease of s and h, and the increase of t and α, the comprehensive performance of the OSFHX is enhanced. The OSFHX exhibits the optimal performance when l = 4 mm. α has the most significant effect on the comprehensive performance of the OSFHX, successively followed by h, s, t, and l. The average error of Colburn factor (j) and friction factor (f) prediction models is 4.09% and 5.31%, respectively, which can realize the theoretical calculation of the performance of the OSFHX for aviation.

Selection of phase change material for latent heat thermal energy storage using a hair-pin heat exchanger: Numerical Study

Abstract Phase change materials (PCMs) are promising for storing thermal energy as latent heat, addressing power shortages. Growing demand for concentrated solar power systems has spurred the development of latent thermal energy storage, offering steady temperature release and compact heat exchanger designs. This study explores melting and solidification in a hairpin-type heat exchanger (HEX) using three PCMs (RT 50, RT 27, and RT 35). A 3D model of the hairpin type heat exchanger (HEX) is drawn using Ansys-workbench. High-temperature fluid/Low-temperature fluid (HTF/LTF) with Stefan numbers (0.44, 0.35, and 0.23) flows through the inner pipe to charge the outer pipe's PCM. The Enthalpy-porosity model is used to study the melting and solidification of various PCMs, and the results were compared. Also, individual thermophysical properties that affect the heat transfer during the melting and solidification process have been discussed. It is observed that low thermal conductivity material with high latent heat is preferred for cold climates. In this study, RT 27 excels in cold climates due to extended solidification time, while RT 50 is effective in tropical regions due to its high melting points and lower latent heat.

Experiments On Gasketed Plate Heat Exchangers with Segmented Corrugation Pattern

Abstract Gasket plate heat exchanger (GPHE) is among the most used heat exchanger types, known for its high effectiveness and compact design. Its remarkable feature is the corrugated plate geometry, typically a Chevron pattern. This work aims to analyze another corrugation pattern, which has segments with different angles to the vertical. The strengths and weaknesses of the segmented plate are still unclear, as the studies on this pattern are scarce. To fill this gap, we experimentally assess the pressure drop and heat transfer in a GPHE composed of 31 segmented plates. The plates have four quadrants, and the combination of low-angle and high-angle plates can form up to six channel types. Pressure and temperature data are acquired in 144 sets of experiments. In the pressure drop results, we observe a considerable discrepancy between the two streams, which leads to a discussion of a relevant phenomenon: the elastic deformation of the plates. If the inner pressure of the streams is not equal, the pressure gradient causes the plates to deform and change the channel geometry. The stream with the higher pressure has its channels expanded, while the lower pressure channels will be strangled. This phenomenon is rarely reported in the literature and strongly affects the pressure drop. Moreover, we present friction factor correlations for six channel types using flow data. Based on the generalized Lévêque analogy in the heat transfer experiments, we argue that the plates' deformation also affects the heat transfer.

Assessing the use of PEC and jf methods for strengthening the evaluation of new heat exchangers

The new type of heat exchanger uses the micro heat pipe as the main heat transfer material. Compared with the traditional heat exchanger of the same kind, the performance of the new type of heat exchanger has significantly improved. By studying the evaluation method of strengthening the performance of the heat exchanger, the performance of the heat exchanger can be further optimized. Most of the current literature study the heat transfer coefficient of the heat exchanger, but there are many influencing factors. Therefore, the evaluation lacks accuracy, and there is no clear research description of fin strengthening performance of the heat exchanger. In this paper, the PEC and jf methods were used in evaluating the enhanced performance of a new type of heat exchanger. Multiple performance indexes were used as evaluation factors and the characteristics of flow and heat transfer were analyzed by studying the working medium, heat transfer coefficient and pressure drop in the heat exchanger. The study, therefore, proposed an optimization direction and the results proved that PEC and jf methods can be used to evaluate the performance of the new heat exchanger efficiently, and the two conclusions were similar. The fins were more capable to improve the performance of heat exchanger when Re >31000.

Comparative Analysis of Influencing Factors on Heat Extraction Performance of Multi-Type Shallow Borehole Heat Exchangers

In this paper, the influence of design parameters and geological parameters on the heat extraction capacity of common coaxial type, single U-type, and double U-type borehole heat exchangers(BHEs) in shallow ground source heat pump system is analyzed, and the heat extraction performance of different types of BHEs is further compared. The results show that with the increase in borehole depth and ground temperature gradient, the outlet temperature of the three types increases at the end of the heating season, and the single U-type BHE increases most significantly. The increase in inlet flow rate will decrease the outlet temperature of the three BHEs, and the U-type is the most obvious decrease. The increase in inlet temperature will reduce the temperature difference between inlet and outlet of the three types BHEs. Given the same design parameters, coaxial-type BHE obtains the maximum heat.

A case study on effect of twisting technique on heat transfer characteristics in a twisted oval helical tube

Efficient transfer of energy is an important issue addressed by numerous scholars in the literature and various methods have been proposed for enhancing the heat transfer efficiency in heat exchangers. Among many different heat exchangers, helical tubes are one of the most prevalent types of heat exchangers which have many applications in industry. In a case study, effect of twisting technique on the heat transfer in a helical tube with oval cross section has been investigated numerically and the results have been compared with simple circular cross section helical tube. Effect of cross section aspect ratio and twisting ratio in different flow Reynolds numbers has been considered. Results have been presented in terms of Nusselt number, friction factor, PEC, entropy generation and contours of velocity, streamlines and temperature. Results indicate that twisting technique can significantly enhance the heat transfer and all cases have PEC values of above unit which indicates superiority of this method. Also the velocity contours and streamlines indicate that using twisting technique result in higher mixing in the flow which is the reason for higher heat transfer characteristics in twisted oval helical tubes.

Calculation Study of Double Pipe Type Heat Exchanger in LNG Plant Pre-Design with Capacity 250 tons/hour

Calculation Study of Double Pipe Type Heat Exchanger in LNG Plant Pre-Design with Capacity 250 tons/hour

Operational proposal of “U” type earth heat exchanger harnessing a non-producing well for energy supply to an absorption cooling system. Approach with “La Primavera” geothermal field data

This paper proposes the operation of “U" type heat exchangers to harness the remaining heat/geothermal energy in a non-producing well and use it in an absorption cooling system. The operational proposals are obtained with a previously validated numerical model that allows modifying geometric and functional parameters of the heat exchanger, in addition to considering information from the well and the absorption cooling system to estimate the temperature of the fluid along the tubes. By taking information from the well, such as the geothermal gradient, the thickness of each stratum, and its thermophysical properties, in addition to the requirements of the absorption cooling system, it is possible to reach more realistic results compared to omitting or assuming any information. In total, 31 different simulations were carried out in which one of the following five parameters was modified: fluid velocity, diameter and total length of the heat exchanger, thickness and length of the insulating material. As a result, 4 different operation proposals are obtained that meet the requirements of the absorption cooling system. In this way, it is possible to combine in a novel way the properties of the well, the characteristics of the absorption cooling system, and the operating parameters of the “U" type heat exchanger.

Design and performance analysis of a Joule-Thomson cryocooler systems

The aim of the work is to develop a mathematical model which has capability to analyses the design parameters as a function of operations conditions for single and multi-stage Joule Thomson Cryocooler System JTCS. The operations conditions are inlet and outlet pressure, precooling temperature, and mass flow rate. The design parameters are expansion device (length, diameter, and Joule Thomson coefficient), heat exchanger (length, diameter, and effectiveness) and gas type (nitrogen, oxygen, and argon). Theoretical results for nitrogen, oxygen, and argon at initial pressure of 25 MPa, initial temperature of 20ºC, indicate that the final temperature equal to (-16.46ºC, −37.34ºC and −56.75ºC) respectively at single stage JTCS. It also shows the possibility of decreasing the final temperature to (-194ºC, −180.9ºC and −183.8ºC) respectively at multistage JTCS. The experimental rig has been constructed for satisfying mathematical model. The experimental results for nitrogen gas show a temperature drop of 6.5ºC when the initial pressure and temperature were 3 MPa and 20ºC respectively. Theoretical results were validated using experimental measurements on the other hand. The computer program has been built to carry out the analysis required for solving the parameters of JTCS under different operations conditions with good agreement compared to recent published researchers.

Airside heat transfer analysis using Wilson plot method of three analogous serpentine tube heat exchangers for aero-engine cooling

This research investigates the design, manufacture and heat transfer characteristic evaluation of three types of heat exchangers (HXs) serving for modern aero-engines. In the field of heat transfer system, previous research has concentrated on large-diameter tubes, whereas estimation for heat transfer in small-diameter tubes commonly relies on correction factors. However, small-diameter heat exchangers offer extensive applicaiton prospects in aero-engines utilizing cooled cooling air (CCA) technology, benefiting from their high heat transfer efficiency and lightweight. Hence, directly investigating compact small-diameter HXs is significant. In this paper, three analogous serpentine tube bundle HXs with different tube diameters (OD: 2.2/1.8/1.4 mm with 0.2 mm thickness) were designed by the Logarithmic Mean Temperature Difference method (LMTD). A series of comparative experiments were conducted to explore the effects of the tube diameter and flow rates on the airside heat transfer under different fuel flow conditions. The results indicate that in the case of turbulent fuel flow, decreasing the tube diameter assists in enhancing total heat transfer, whereas the trend is opposite in laminar fuel flow. In addition, during turbulent fuel flow, heat transfer capacity rises with the increase of flow rates on both sides, while variations in air flow rate have minimal impact on airside heat transfer in laminar fuel flow. Finally, the calculated heat transfer rate exceeds the experimentally measured value by no more than 15%, with this deviation escalating as the reduction of tube diameter. Subsequently, an airside Nu-Re correlation suitable for small-diameter HXs is fitted based on experimental data, with 94.1% of the data points locate in the 5% error band, providing guidance for the design and validation of aero-engine HXs in future.

STUDY OF THE EFFICIENCY OF THE FUNCTIONING PROCESS OF THE MECHATRONIC SYSTEM OF ENSURING THE MICROCLIMATE OF ANIMAL PREMISES

The development of the livestock industry is the basis of Ukraine's food security. One of the ways to solve this problem is to improve the conditions of keeping animals, including improving the microclimate of livestock and poultry premises. Modern animal husbandry technologies make high demands on the microclimate in livestock premises. According to scientists, animal husbandry specialists and technologists, animal productivity is determined by 50...60% feed, 15...20% by care, and 10...30% by the microclimate in the livestock premises. Deviation of the microclimate parameters from the established optimal limits leads to a decrease in milk yield by 10...20%, an increase in live weight – by 20...35%, an increase in the departure of young animals to 5...40%, and a decrease in laying hens – by 30%...35%, costs of an additional amount of feed, shortening the service life of equipment, machines and the buildings themselves, reducing the resistance of animals to diseases, negatively affecting the service personnel. The article presents a structural and technological scheme of a mechatronic system for ensuring a normative microclimate of livestock premises, which allows to increase the efficiency of ensuring a normative microclimate of livestock premises by using a mechatronic system for controlling the process of air disinfection using ultraviolet radiation of bactericidal lamps. According to the results of numerical modeling of the air heat exchanger of the indirect-evaporative type, the distribution of the temperature field, vector field of velocities and absolute air humidity in channels of different shapes (square, equilateral triangle, circle) was established. The calculated coefficient of thermal efficiency of the heat exchanger with triangular shaped channels is the whitest in contrast to square and round shapes. A comparative analysis of humidity distribution in channels of different shapes confirms that the absolute humidity of the thermal air flow decreases earlier in the indirect-evaporative type heat exchanger with triangular channels.

An investigation shell and tube heat exchanger for cooling system: A case study of biodiesel plants using lauric acid

Shell and Tube Heat Exchanger (STHE) is a commonly used type of heat exchanger in various industries due to its cost-effectiveness and ease of maintenance. Continuous washing and maintenance of STHE play an important role in influencing both the quality and quantity of production from biodiesel plants. In this particular investigation, the STHE serves as a cooling medium for biodiesel production, with cooling water circulating on the tube side and biodiesel flowing on the shell side. This study focuses on removing silica crust buildup caused by cooling water in the Shell and Tube Heat Exchanger. Furthermore, a Clean-in-Place machine and a 10 % citric acid solution with variable washing times of 2 h, 4 h, 6 h, 8 h, 10 h, and 12 h were used for the cleaning process. The results indicate a significant 250 % increase in the volumetric flow rate of the cooling tower along with an increase in the overall Heat Transfer Coefficient after 10 h of washing. Further analysis at the hours mark showed consistent results, suggesting a steady state. Beyond this point, no additional temperature decrease was observed, with temperature stabilizing at 32 °C. The results of the Scanning Electron Microscope analysis show that the crust formed in the STHE comes from silica found in cooling water.

Thermal performance evaluation during charging/discharging cycles of sensible energy storage beds for biogas production process

The breakdown of organic waste, through anaerobic digestion, for production of biogas is a temperature dependent process. The favorable temperature required for efficient production is 35 °C. Attaining the temperature required for this process, under normal conditions, is a challenging task. Hence, the development of an effective heating system is necessary. The warm water from the solar water heater is circulated through the wall of the digester wall using a heat exchanger. The intermittency in the supply of energy, as in the case of solar radiation, creates a mismatch between the demand and the supply of the energy. Hence, development of efficient energy storage system that can be used as stand-by in case of unavailability of the primary energy source.The present work modeled and predicted the thermal performance of sensible heat storage system having 10 MJ capacity which can deliver warm water at 35 °C for 4 hr. The sensible heat storage system unit is a regenerator type heat exchanger which stores/releases heat on passing hot/cold heat transfer fluid through the tubes embedded into it. A mathematical model of a cylindrical configuration with embedded multi-tube is developed employing pebbles and cast iron as storage mediums. The number of embedded charging/discharging tubes in the storage model is optimized based on the charging time using a finite element method based simulation tool (®COMSOL Multiphysics). A parametric study, including charging/discharging time, energy stored/recovered, exergy stored/recovered, and charging/discharging fraction of the system, have been used to evaluate the thermal performance. Further the effect of heat transfer fluid tube diameter and velocity, volumetric heat capacity and thermal conductivity of the storage media on performance of the storage is also investigated.