Coil Heat Exchanger Research Articles

Natural convection heat transfer using water-based nanofluid in a shell and helical coil heat exchanger

Industry is looking for more efficient ways to use nanomaterials to decrease water consumption. The addition of greater thermal conductivity nanoparticles to the water enhances the fluid's thermal conductivity and, thus, increases the coefficient of heat transfer. In this work, water-based nanofluids were used to perform heat transfer enhancement studies in a shell and helical coil heat exchanger. Natural convection heat transfer using three water-based nanofluids (Al2O3, CuO and TiO2/water) was investigated in shell and helical coil heat exchanger. Experiments were performed at different hot water flow rates through coil (Dean number) and hot water feed temperatures (40, 50 and 60 °C). The use of water-based nanofluid led in a greater coefficient of shell-side heat transfer compared to the use of pure water on the shell side. The Nusselt number improved due to an increase in nanoparticle concentration. It was observed that with a rise in nanofluid concentration, Dean number and greater coil-side fluid feed temperature, the Rayleigh number increased.

Intensified single-phase forced convective heat transfer with helical-twisted tube in coil heat exchangers

The twisting structure is proposed to enhance the thermal performance of a coil heat exchanger equipped with the helical tube. Actually, it intensifies the fluid mixing and breaks continuously increased thickness of thermal boundary layers. Firstly, experiments are conducted on a smooth helical tube, and the obtained results are validated using correlations proposed by other researchers. A reasonable agreement within ±7% is detected. Then, simulations are carried out to apprise the benefits of helical-twisted tube as compared to the original geometry, i.e. helical tube. It is found that the twisted walls prevent the development of thermal boundary layers through the flow direction and change continuously the location and strength of generated secondary flows and velocity contours, leading to more uniform temperature. At the studied range of Reynolds number (600 ≤ Re ≤ 1200), the Nusselt number enhancement of 14.2% and the friction factor augmentation of 7.7% are recorded for a model at middle levels of design parameters. Finally, a parametrization analysis is performed to find the effects of each specific design parameter (helical-diameter, helical-pitch, and twist-pitch). It is observed that the helical-diameter has the highest impacts on thermal–hydraulic characteristics of the helical-twisted tube, and the twist-pitch and helical-pitch come in the second and third, respectively. The overall hydrothermal performance improves as both the helical-diameter and the twist-pitch are decreased. The maximum performance index of 1.98 is obtained for the model with the helical-diameter of 50 mm at the Reynolds number of 900.

Comparative numerical study of flow characteristics in shell & helical coil heat exchangers with hybrid models

The present paper dispenses with effectiveness and energy actions of Shell and Coil heat exchanger used to reject heat from working fluid in industries. In particular, shell and coil heat exchanger had examined for 3 vivid coil configurations, so to examine the flow attributes for these models for common boundary conditions and under varying working operations. Important inference reflected out are rate of heat transfer from heat exchanger and effectiveness for all the three systems. Computations had been formulated using the software Ansys Fluent and it had covered the simulations for all the different working operations separately for all the heat exchangers. The major attribute for rate of heat transfer enhancement of numerical models pointed is the overall heat transfer coefficient which depends on coil thermal conductivity. The value of volume flow rate in tubes were found another essential element. The shell-helical coil heat exchanger arrangement resulted as preferred one over other two heat exchanger due to its consistency while slinky coil can be used for enhanced heat transfer conditions if total pressure drop is not a performance measuring parameter.

Анализ применения системы рекуперации тепловых потерь с помощью органического цикла Ренкина для привода технологического оборудования

The analysis of heat exchange processes during cooling of the heated surface of the process equipment is carried out on the basis of the equations contained in the ANSYS Fluent package. When modeling heat exchange processes, the following boundary conditions are adopted: the temperature of the heated surface; the coil heat exchanger is located at a distance from the heated surface of the process equipment. From these results, we can draw the following conclusions: the increase in the temperature of the heated surface leads to the increase of the heating zone of the refrigerant with high capacity and, hence, to increase heat capacity; increasing the refrigerant flow rate, the lower the temperature of the refrigerant at the exit, but increases the thermal capacity; increasing the pressure of the heated refrigerant increases the thermal; this design of the heat exchanger allows you to achieve the necessary power for the operation of the drive by: changing the flow rate of the refrigerant, the excess pressure of the refrigerant, the number of elbows, as well as by installing a heat-reflecting casing

The Effect of Injected Air Bubble Size on the Thermal Performance of a Vertical Shell and Helical Coiled Tube Heat Exchanger

In the present study, the effect of injecting air bubble size on the thermal performance of a vertical counter-current shell and coiled tube heat exchanger is experimentally investigated. The experiments were accomplished in ... | Find, read and cite all the research you need on Tech Science Press

Experimental study on thermal analysis of helical coil heat exchanger using Green synthesis silver nanofluid

Abstract Green Synthesis of silver nano particles using Neem leaf extracts and preparation of nanofluid, heat transfer, pressure drop and friction factor for helical coil heat exchanger have been experimentally investigated and compared with the standard correlation given by various researchers is discussed in this paper. Inlet temperatures of hot water on coil side and cold water on shell side were maintained at around 58 °C and 32 °C respectively. Experiments were performed over the Dean number range on shell side is 1000 to 3000, by varying mass flow rate and Reynolds number on coil side is kept constant at 5780. Thermal analysis has been carried out by considering various parameters such as temperature, flow rate, overall heat transfer coefficient. Use of green synthesized Nano particles have shown enhancement of 32% in heat transfer coefficient compared to base fluid. Thermal performance factor has been slightly decreased with increase in concentration and is feasible to use 0.05% of concentration nanofluid.

РЕЗУЛЬТАТЫ УПРОЩЕННОГО МАТЕМАТИЧЕСКОГО МОДЕЛИРОВАНИЯ РАСПРЕДЕЛЕНИЯ ТЕМПЕРАТУРЫ ЖИДКОСТИ В ТЕПЛООБМЕННОМ КАНАЛЕ ЭЛЕКТРОНАГРЕВАТЕЛЯ С ВНУТРЕННИМ ИСТОЧНИКОМ ТЕПЛОТЫ

Indirect electrical resistance heating systems are heat-ers with internal heat sources and are widely used in agri-culture for heating gaseous and liquid media. Such sys-tems are characterized by insufficient intensity of heat ex-change processes. This implies a large heat transfer sur-face area and significant geometric size. Earlier, an attempt was made to solve the problem of increasing the efficiency of heat transfer processes and minimizing the geometric size of the heat exchanger. For this purpose, the heat ex-change characteristics were simulated and the geometric dimensions of three heat exchange systems were deter-mined: “pipe with internal heat sources in a dielectric pipe”, “pipe with an internal heat source -a membraneof heated liquid” and “cylindrical coil -heated liquid”. The analysis of these heat exchange systems has shown that the most promising is a coil-type heat exchanger. This system has the best heat transfer characteristics and the most compact size. To confirm the correctness of the applied method of calculating the heat exchange and geometric parameters of the heat exchanger, the simulation of the temperature dis-tribution of the heated liquid in the channel of the coil heat exchanger is implemented in this work. The verification calculations carried out under the formulated assumptions, using the example of a coil heat exchanger, show that the method for determining the heat exchange and geometric parameters of heat exchangers is correct. As a result of the simulation, it has been found that the error in determining the required channel length of the coil heat exchanger, the number of turns and the height of the coil to reach the liq-uid temperature at the outlet of 75°C does not exceed 4%. A similar conclusion can be made regarding the heat ex-changers of the types “pipe with internal heat sources -heated liquid” and “pipe with an internal heat source -a membraneof heated liquid”.

Performance analysis of heat transfer parameters in shell and tube heat exchanger with circumferential turbulator

Performance of heat exchanger is evaluated by the value of heat transfer coefficients, Reynolds number, Nusselt number, temperature distribution along the length, residence time and pressure drop. Improving these parameters for better performance is the main focus in designing the heat exchanger. In that view, helical coil gives more turbulence to the fluid flowing through it that leads to improved tube side heat transfer coefficient. For increasing the turbulence in cold flow, turbulators can be used in the circumferential area between helical coil and shell. In this work, heat transfer rate of shell and helical coil heat exchanger is improved by using circumferential turbulators. For the same mass flow rate of cold fluid different hot fluid mass flow rates (0.03 kg/s, 0.06 kg/s, 0.09 kg/s and 0.12 kg/s) were fixed for taking readings and the improvement is obtained by calculation of performance parameters. The temperature distribution along the length of the heat exchanger is plotted for different flow rates. Results show that, increasing the mass flow rate of cold fluid above the mass flow rate of hot fluid decreases the performance.

Analytical study of photovoltaic thermal compound parabolic concentrator active double slope solar distiller with a helical coiled heat exchanger using CuO nanoparticles

Analytical study of photovoltaic thermal compound parabolic concentrator active double slope solar distiller with a helical coiled heat exchanger using CuO nanoparticles

EXPERIMENTAL INVESTIGATIONS ON HEAT TRANSFER ENHANCEMENT FOR HORIZONTAL HELICAL COIL HEAT EXCHANGER WITH DIFFERENT CURVATURE RATIOS USING CARBOXYMETHYL CELLULOSE-BASED NON-NEWTONIAN NANOFLUIDS

EXPERIMENTAL INVESTIGATIONS ON HEAT TRANSFER ENHANCEMENT FOR HORIZONTAL HELICAL COIL HEAT EXCHANGER WITH DIFFERENT CURVATURE RATIOS USING CARBOXYMETHYL CELLULOSE-BASED NON-NEWTONIAN NANOFLUIDS

Analysis of tube-in-tube copper helical heat exchanger to improve heat transfer

The present work aims to investigate the effect of different configurations of tube-in-tube helically coiled heat exchanger. Commercial CFD codes were used to predict the fluid flow and heat transfer in a tube-in-tube helical heat exchanger. The model of different configurations of the inner tube has been simulated by varying the dean number. The numerical results are verified and found to be in good agreement with reported data in the literature. Nusselt Number and friction factor are evaluated for different angular positions. The use of geometry E increases the Nusselt Number and friction factor by 17.05% and 15% respectively at a Dean number of 400 as compared with a circular tube.

EXPERIMENTAL AND NUMERICAL STUDY OF INSERTING AN INTERNAL HOLLOW CORE TO FINNED HELICAL COIL TUBE-SHELL HEAT EXCHANGER

In the present study, an experimental study and a numerical method are used to simulate the effect of utilizing finned helical coil heat exchanger horizontally oriented with and without internal hollow core inside the shell and monitoring the heat transfer intensification behavior and performance enhancement, by using ANSYS FLUENT 2019R3 package. The working fluid in the inlet side of the coil will be superheated vapor refrigerant (R410a) after the compression stage of the air conditioner (1TR) split type, the working fluid in the shell side is water with various flow rates (1,2 and 3) LPM. Found that when using a heat exchanger with internal hollow core reduces the time needed to reach the steady-state outlet temperature and directly proportional to the size of the core by 20% and slightly increasing the water outlet temperature by 5%.

Study on Heat transfer and Pressure Drop in Tube-In-Tube Helical Heat Exchanger

ABSTRACT The present work aims to investigate the effect of different configurations of the tube-in-tube helically coiled heat exchanger. Commercial CFD codes were used to predict the fluid flow and heat transfer in a tube-in-tube helical heat exchanger. The model of different configurations of the inner tube has been simulated by varying the Dean number. The numerical results are verified and found to be in good agreement with reported data in the literature. Nusselt Number and friction factor are evaluated for different angular positions. The use of geometry E increases the Nusselt number and friction factor by 19.05% and 16% respectively at a Dean number of 4000 as compared with a circular tube as compared with the circular tube.

Performance of wire finned coiled tube heat exchanger in a small J-T refrigerator

Non-azeotropic, mixed refrigerant of hydrocarbons nitrogen takes place in heat exchangers while boiling and condensation simultaneously at various cryogenic temperature and pressure. It is very difficult to design a heat exchanger in order to undergo boiling and condensation simultaneously. In the present paper, heat exchanger is designed numerically by applying the steady state conditions. Heat transfer coefficients are calculated numerically by applying homogenous model, which is developed by writing a computer programme. This model is validated with the experimental data. This study is carried out with three different refrigerant mixtures. Also, observed that a significant increase in percentage of heat transfer coefficient values in all the three mixtures considered in this study. It is found that 50% increase in tube side and 33% in shell side in the mixture 1 whereas in the mixture 2 it is 31% and 18% and similarly in the mixture 3 the increase is 40% in tube side and 20% in shell side. So the refrigerant with mixture 1 will perform better. Further the study is extended to heat exchanger with wire fin wound around the inner tube. It is observed that there is a significant improvement in heat transfer coefficient when wire fin is used.

Optimization of Helical Coil Tube Heat Exchanger: A Systematic Review

Helical coil heat exchanger is used in the food industries, air cooling industries etc.., due to its advantage of structural compact and high heat transfer coefficient. Many existing researches have been carried to improve the heat transfer efficiency and pressure drop. Mathematical model of the heat exchanger has been used to validate the performance of the heat exchanger. This paper involves in review the researches related to the optimization of helical coil tube heat exchanger. Some of the optimization methods such as Taguchi method, Genetic Algorithm (GA) and Multi-Objective Genetic Algorithm (MOGA) is used. From the analysis, Artificial Neural Network (ANN) and GA method has efficient performance in modelling and optimization of heat exchanger. Although, some methods involved in economic optimization of heat exchanger and these method has lower performance.

Experimental and numerical analysis of a cement based thermal energy storage system with a helical heat exchanger

This study presents a combined experimental and numerical investigation of the performance of a new modular sensible heat storage system with a cement based, water saturated, porous storage matrix and a helical tubular heat exchanger during cyclic storage operation. To characterize the storage system with respect to achievable storage rates and storage capacity, two sets of dedicated and highly controlled dynamic charging-discharging cycles were experimentally conducted using a one cubic meter lab-scale storage unit prototype. A prognostic process based and high resolution 3D finite element model for this storage unit was developed, tested and validated by comparison to the experimental data. The overall model agreement with the experimental data is excellent, also for extended cyclic storage operations using up to nine charging-discharging cycles, with root mean square errors of temperatures within the storage unit smaller than 1.3 °C, heat balances within 3% of the experimental value and an average Nash Sutcliffe model efficiency index as high as 0.993. The numerical model could thus be used for application specific, simulation based storage design and dimensioning by simulating storage performance for modified heat exchanger geometries, component materials and operational boundary conditions. The simulation results indicate, that the heat transfer rate of the laboratory prototype can be increased by up to 150% for short-term (i.e. <1 h) and up to 90% for mid-term (<6 h) charging durations, respectively, by employing an elevated charging temperature, increasing the thermal conductivity of the storage medium and heat exchanger pipe, and decreased heat exchanger coil pitch height. The corresponding achievable short- and mid-term charging capacities can thus be improved by about 170 and 130%.

Exergy analysis of Shell and helical coil heat exchanger and design optimization

In this study, experimental investigations and exergy analysis on shell and helically coiled tube heat exchanger are carried out for free convection heat transfer. The measured data are totally optimised utilizing thermodynamics rules in which exergy study is performed to investigate the thermal performance of the helical system under different operating conditions. The experimental set-up of apparatus are designed and made for cold water and hot water as a working fluid of both the shell side and helical coil side, respectively. The effects of several parameters such as geometry and operational conditions on the exergy destruction and dimensionless exergy destruction are investigated. The counter flow direction is considered under the steady state flow condition, and the critical Reynolds number was more than 4000 in this study. The main objective of this work was to clarify the effect of the volume flow rates and inlet temperatures of hot water and cold water in the shell and helical coil on exergy efficiency and pressure drop. Results showed that the exergy destruction and dimensionless exergy destruction decrease with the increase of coil pitch and Dean number. In contrast, the exergy destruction and dimensionless exergy destruction are obviously increased with the hot water flow rates or cold water flow rates. These exergy characteristics are also augmented with the values of hot water inlet temperatures and cold water inlet temperatures. The pressure drop is considerably increased with the increase of Dean number and reduced with the increase of coil diameter. While, the exergy efficiency steadily increases with the decrease of the cold water flow rates and with the increase of Dean number.

Analysis of thermal performance of an improved shell and helically coiled heat exchanger

Shell and helically coiled tube heat exchangers composed from curved tubes inside a shell which are often preferred devices particularly in several applications like refrigeration, heat recovery systems, chemical processing, heat storage and food processing. Enhancing the effectiveness of heat exchangers can leads to increase in the overall efficiency of energy conversion systems. In addition, finding a simple and cost-effective method for enhancing the effectiveness of heat exchangers is a significant issue that should be taken into consideration. In this work, it is proposed to enhance the performance of a shell and helically coiled heat exchanger by utilizing a new modification. Within this context, a hollow tube integrated into the shell side and cold fluid enters the heat exchanger along this tube. The main purpose of this modification is regulating the fluid flow over the helically coiled tube and consequently obtaining more thermal energy. In this regard, the performance of a modified shell and helically coiled heat exchanger has been compared with a conventional vertical shell and helically coiled heat exchanger by using numerical simulation. The main objective of the simulation part of this study is determining suitable configuration for shell and helically coiled tube heat exchanger to obtain high thermal performance. Then, modified shell and helically coiled heat exchanger has been fabricated by considering simulation results. Finally, the performance analysis of developed heat exchanger has been experimentally conducted under different conditions to determine its behavior. The findings of this work showed the successful design of the modified heat exchanger. Generally, it can be said that integrating a hollow tube into the shell side of the heat exchanger led to regulate the fluid flow in the shell side that improved heat transfer. Overall heat transfer coefficient obtained in the range of 1600–3150 W/m2 K. Also, heat transfer coefficient of coil side in this study was obtained in the range of 5700–13,400 W/m2 K. Moreover, average difference between simulation and experimental results is 8%.

Experimental shell-side surface pressure measurements on tubes within a model helical coil heat exchanger

The tube and shell Helical Coil Heat Exchanger (HCHX) geometry, also known in multiple industries as the Coil-wound (CWHE), and Spiral-wound heat exchanger (SWHE), has recently been under greater investigation due to the interest in cryogenic, solar, and nuclear industry applications. Helical Coil Steam Generators (HCSGs) have adjacent tube bundles that coil in opposite directions at different helical pitches. While this design is known to increase heat transfer and provide a higher volumetric efficiency, few studies look at the changes the coiling arrangement has on forces acting on the tube. This study investigates the pressure on the surface of the tubes in this complex type of cross-section arrangement as compared to standard tube bundle arrangements. Experiments were conducted at Reynolds Numbers 8500 and 11,700 based on tube diameter and free-stream velocity. Pressure Sensitive Paint (PSP) was used on the shell-side surface of the tubes along with dynamic pressure sensors to visualize tube surface pressure and measure pressure fluctuations. Instantaneous pressure analysis using PSP and dynamic pressure transducers showed agreement with peaks of transient pressure fluctuations at approximately 9.8, 19.7 and 27.5 Hz. Previous studies have grouped tube surface pressure based on geometric parameters such as lateral pitch ratio, while the analysis of the pressure fields from this geometry showed pressure profiles unique to individual planes regardless of equivalent lateral pitch ratio.

Engineering Calculation and Experimental Study of a Cone-Shaped Coil Heat Exchanger

To improve the characteristics of heat and power equipment, it is necessary to develop new designs of heat exchangers, increase the efficiency of heat exchange surfaces, apply modern approaches to the design and calculation of heat exchangers, and create new technologies for their production. The paper proposes modern compact coil heat exchangers of the in pipe type with a variable bending radius of the helical spiral and the engineering method calculating the thermohydrodynamic characteristics of such devices. The calculation of a coilheat exchanger with a linearly varying bending radius of a helical spiral (cone-shaped coil heat exchanger) has been performed. They performed the experimental study of heat transfer in a cone-shaped coil heat exchanger of the pipe-in-pipe type. They obtained the empirical formulas for the Nusselt number and hydraulic resistance coefficient. It has been established and experimentally confirmed that cone-shaped coil heat exchangers are morecompact and efficient in comparison with the known cylindrical coils. It is proposed to modernize the hot water preparation unit in one of the residential buildings in the city of Kazan (Russia) by replacing the outdated shelland-tube heat exchanger with a compact cone-shaped coil heat exchanger, which made it possible to reduce the duration of hot water preparation significantly, to reduce the costs of the heating medium and, thus, to reduceconsumer costs.