Double Exchanger Research Articles

Numerical investigation of the effect of fluid nanohybrid type and volume concentration of fluid on heat transfer and pressure drop in spiral double tube heat exchanger equipped with innovative conical turbulator

Spiral heat exchangers in the heat transfer field have attracted researchers' attention due to their better heat transfer characteristics. This review discusses the increase in efficiency of this type of converter. to better understand the efficiency of the intended spiral exchanger, thermal efficiency (performance evaluation criteria) was chosen as the performance index in the present work, and the simulations were carried out in a calm regime (200<Re<800) and for two positive and negative flows and using three types of fluids. This study aims to conduct a numerical analysis of the impact of nanohybrid fluid type and fluid volume concentration on heat transfer and pressure drop in a spiral double-double-tube exchanger incorporating a conical turbulator. Computational fluid dynamics was employed in the study. The problem is tackled using ANSYS FLUENT 18 to conduct CFD simulations utilizing the finite volume method. The numerical findings indicate that employing countercurrent flow and a nanohybrid fluid of Water/MoS2–Fe3O4 significantly impacts overall performance, potentially boosting the spiral heat exchanger's efficiency by 8 %. The findings indicated that raising the volume concentration of the nanohybrid fluid Water/MoS2–Fe3O4 from 0.3 % to 0.5 % and 0.7 % leads to a notable enhancement in the thermal efficiency of this converter type. The converter achieves its peak efficiency at Reynolds number 200 when using the nanohybrid fluid Water/MoS2–Fe3O4, resulting in a 4 % and 17 % increase in thermal performance compared to the other two concentrations.

Heat Transfer Improvement Using Three Types Novel Turbulators Inserts with Two Pitch Ratios in Double Pipe Heat Exchanger

Heat Transfer Improvement Using Three Types Novel Turbulators Inserts with Two Pitch Ratios in Double Pipe Heat Exchanger

Experimental investigation of the performance attributes of a double pipe heat exchanger equipped with baffles of conventional or flower layouts

In industrial heat management, the design of baffles within heat exchangers is crucial. They guide fluid flow and enhance turbulence, optimizing heat transfer. Yet, their configuration must be carefully considered to balance thermal efficiency with energy expenditure and pressure management. This research conducts practical tests on the hydrothermal attributes of a counter-flow double-pipe heat exchanger. It evaluates two baffle layouts: segmental and flower, considering baffle cut-off ratio (16.7 %≤δ ≤ 50 %), pitch ratio (8.3 %≤λ ≤ 22.2 %), flower-design relative angle (30°≤γ ≤ 90°), and operating conditions of annulus-side (2660 ≤ Rean ≤ 13110, 5.21 ≤ Pran ≤ 7.48). The findings assure that installing the baffles results in notable increases in both Nu¯an and fan. Besides, lowering baffle cut-off and pitch ratios, and increasing the relative angle of flower baffles lead to additional increases. Moreover, raising the annulus-fluid temperature reduces Nu¯an with a negligible effect on fan. Increasing Rean leads to a reduced fan and greater Nu¯an. Compared with no baffles, the maximum recorded increases in the Nu¯an and fan are 147.4 % and 60.2 %, respectively, realized by incorporating flower layout. On average, the flower baffles boost the Nu¯an by 20.8 % more than those using conventional baffles, with an average increase of 4.3 % in the fan. To judge the benefit of utilizing baffles, the Hydrothermal Performance Index (HTPI) is calculated, and its highest value is recorded as 2.23, attained by running the annular pipe at the lowest flow rate and temperature, with inserting flower baffles (δ = 16.7 %, λ = 8.3 %, γ = 90°). Finally, correlations for Nu¯an, HTPI, and fan prediction are suggested.

Design and Performance Analysis of a Small-Scale Prototype Water Condensing System for Biomass Combustion Flue Gas Abatement

This article outlines the design and performance of a flue gas condensation system integrated with a biomass combustion plant. The system comprises a biomass plant fuelled by wood chips, generating flue gases. These gases are condensed via a double heat exchanger set-up, extracting water and heat to reduce concentrations of CO, CO2, and NOx while releasing gases at a temperature close to ambient temperature. The 100 kW biomass plant operates steadily, consuming 50 kg of wood chips per hour with fuel energy of 18.98 MJ/kg. Post combustion, the gases exit at 430 °C and undergo two-stage cooling. In the first stage, gases are cooled in a high-temperature tube heat exchanger, transferring heat to air. They then enter the second stage, a flue gas/water heat exchanger, recovering sensible and latent thermal energy, which leads to water condensation. Flue gas is discharged at approximately 33 °C. Throughout, parameters like the flue gas temperatures, mass flow, fuel consumption, heat carrier temperatures, and water condensation rates were monitored. The test results show that the system can condense water from flue gas at 75 g/min at 22 °C while reducing pollutant emissions by approximately 20% for CO2, 19% for CO, 30% for NO, and 26% for NOx.

Investigation of refrigerant-dependency on the performance of conical double helix tube Joule-Thomson cryocooler

Miniature Joule-Thomson (J-T) cryocoolers are widely used in the cryogenic field due to their advantages of small size, and fast cooling. Selecting the appropriate refrigerant is a crucial task in designing a J-T cryocooler, as it significantly affects its cooling performance. To study the refrigerant-dependent influencing on the cryocooler's performance, an improved one-dimensional model for a conical double layer J-T cryocooler was developed. The model has been verified to have higher accuracy, faster computing speed, and applicability across a wider range of operating conditions. Nitrogen and argon, commonly used refrigerants with similar saturation temperatures, were investigated. Both simulation and experimental results indicate that argon exhibits a faster cooling rate, while nitrogen achieves a lower cooling temperature under the working conditions. The numerical studies suggest that argon's higher density and lower J-T coefficient contribute to its faster cooling characteristic, resulting in a higher heat transfer quantity in the double layer heat exchanger. However, increasing the vessel pressure can quickly reduce the difference in cooling rates between nitrogen and argon, and it may even make nitrogen more optimal. Moreover, it was observed that a significant portion of the cooling capacity is utilized to cool the cryocooler itself for both nitrogen and argon.

Effects of multi-spring wires on hydrothermal performance of double tube heat exchanger

Double-tube heat exchangers play a vital role in industries by facilitating efficient heat transfer between two fluids while keeping them physically separated. Their design offers versatility, reliability, and ease of maintenance, contributing to improved process efficiency, energy conservation, and cost savings across a wide range of applications. This study investigates the influence of multi-spring wires on the performance of double-tube heat exchangers using A CFD turbulence model. The analysis covers friction factor, Nusselt number, and exergy efficiency across Reynolds numbers spanning from 4500 to 7500. Employing a steel spring wire of 2 mm diameter and 1000 mm length in three configurations (1, 2, and 3 springs), the results reveal a consistent increase in Nusselt number with rising Reynolds number. Notably, a 3-wire configuration demonstrates a 112 % enhancement in Nusselt number compared to plain tubes, with a maximum friction factor increase of 134 %. Exergy efficiency experiences significant improvement, rising by 61 % with the 3-wire setup compared to plain tubes. Additionally, the study predicts temperature, pressure, and velocity distributions along the tube through numerical analysis of the results. This study improves the energy efficiency and sustainability of double-tube heat exchangers using multi-spring inserts, lowering emissions and costs while advancing thermal management systems.

Performance Analysis of Double Pipe Heat Exchanger Using Nano Fluids

Choosing an appropriate heat transfer fluid is a crucial factor in the design of a heat exchange system. A nanofluid is a colloidal mixture composed of a base fluid and nanoparticles. It is a promising heat transfer fluid in various applications due to its improved thermal conductivity and heat transfer rate. The increasing demand and acceptance for nano-fluids as heat transfer fluids in various applications have led to an increase in research investigations on this topic. Nanofluid technology has recently expanded to include the impregnation of multiple nanoparticles in base fluids, known as hybrid or nanocomposites. For this study, we have chosen three distinct nanoparticles and two base fluids to examine their thermo-physical characteristics and heat transmission rate. Nanofluid is prepared via the sonication method. The experiment is used to determine the thermosphysical characteristics of various nano-fluids. The double-pipe heat exchanger is employed to measure the heat transfer rate and efficiency of nano-fluids. Among six samples prepared in the present work, the ZnO2+CNT+TiO2+EG sample had shown reduced kinematic and dynamic viscosities for all the temperature ranges. However, an average value of heat transfer rate was recorded for ZnO2+CNT+TiO2+EG at 675.87 (J/s) for parallel flow and 630.79 (J/s) for counter flow. And the least effectiveness was recorded for distilled water. The hybrid nanofluid demonstrates a superior heat transfer rate and effectiveness in both parallel flow and counter flow applications. Therefore, it may be efficiently utilised in many heat transfer applications.

An Investigation on Concurrent and Countercurrent Heat Transfer Performance in a Double Pipe Helical Coil Heat Exchanger Using CFD

An Investigation on Concurrent and Countercurrent Heat Transfer Performance in a Double Pipe Helical Coil Heat Exchanger Using CFD

An experimental investigation of the convective heat transfer augmentation in U-bend double pipe heat exchanger using water-MgO-Cmc fluid

One of the major problems of using nanofluids in heat exchange applications is the forming and deposition of nanoparticles on the inner surface of the heat exchanger. In this paper, Water-Cmc fluid is used as a surfactant for nanoparticles to prevent deposition and congregation. The pressure drops and heat transfer in U-bend double pipe heat exchanger based on water-MgO-Cmc fluid, are examined. Nanoparticles of Magnesium Oxide (MgO) and Carboxymethyl Cellulose (Cmc) are used with pure water as a base fluid. The experimental rig and procedures are designed to facilitate various operational conditions such as flow rate, volume concentration of MgO particles and weight concentration of Cmc particles. Furthermore, convective heat transfer coefficient, heat exchanger effectiveness, pressure drop, friction factor, under different conditions, are measured. The results demonstrate convective heat transfer coefficient of U-bend double pipe heat exchangers is enhanced by 35% for 1 MgO vol.% and 0.2 Cmc wt.% compared to base fluid (Water-Cmc). It is concluded that pressure drops are directly proportion to the increase of MgO nanoparticles at same Cmc concentration by 23% at 0.2 wt.%. Whilst, friction factor of the system is inversely proportion to the increase of volumetric flow rate of water-MgO-Cmc fluid. An increase in MgO nanoparticle concentration increases the friction factor, hence maximum friction factor enhancement by 38% for MgO concentration of 1 vol.%. The effectiveness of heat exchanger is slightly increased by 8% with increase of MgO concentration and flow rate. Finally, thermo-physical characteristics of water-MgO-Cmc fluid at various temperatures, are measured

Investigation by monitoring and numerical simulation of the performance of a ground-source heat pump system with and without regeneration in different configurations and operating modes

This paper is focused on restoring the thermal imbalance of the ground caused by conventional GCHP systems through seasonal and continuous regeneration using a geothermal-solar facility with a vertical GCHP combined with photovoltaic (PV) and PV-thermal (PV/T) panels in a heating-dominated climate, located in Timisoara, Romania. Therefore, the performance of a GCHP system integrated into the heat supply system of an experimental office, operating in single and double U-tube borehole heat exchanger (BHE) configuration, with regeneration in the summer months by injecting heat into the ground, is experimentally evaluated. Exploratory research has indicated an increase in the average temperature of the working fluid by 2.4% and an improvement in system performance when using heat injection (seasonal performance factor (SPF) by 3.5% and 6.6% higher and CO2 emission by 1.2% and 3.8% lower in the single and double U-tube BHE configurations, respectively). Additionally, numerical simulations with Polysun software are also used to test the performances of the hybrid GCHP-PV/T system with continuous regeneration throughout the year by PV/T panels and of a conventional GCHP integrated into the heating and DHW production systems for a single-family building. The simulations were experimentally validated through measurements on the geothermal-solar facility for heating and DHW production in the experimental office. The simulation results show that the SPFHP-PV/T values of the hybrid GCHP-PV/T system in the single and double U-tube BHE configurations, equal to 6.00 and 5.79, respectively, are 32% and 34% higher than the SPFHP corresponding to the conventional GCHP system, equal to 4.56 and 4.32, respectively. In addition, the SPFHP-PV/T in the single U-tube BHE configuration is 3.6% higher than in the double U-tube BHE configuration for the GCHP combined with the PV/T array (31.8 m2).

Heat transfer enhancement in double pipe heat exchanger: exploring twisted tape inserts with dimple configuration

Heat transfer enhancement in double pipe heat exchanger: exploring twisted tape inserts with dimple configuration

Numerical simulation study on heat transfer performance of double U-shaped buried pipe heat exchanger

The core component of the ground source heat pump (GSHP) system is the buried pipe heat exchanger. It is critically important to analyze its thermal exchange efficiency for safe and consistent functionality. Taking the double U-shaped buried pipe group as the study subject, this research constructed a three-dimensional model using computational fluid dynamics (CFD). The influence of the spacing and drilling depth on the heat transfer performance was analyzed. Further investigation was conducted on how 15 years of uninterrupted operation of the buried pipes affects the temperature field of the surrounding soil. The spacings between buried pipes were set to 4 m, 4.5 m, 5 m, 5.5 m, and 6 m, with drilling depths fixed at 150 m and 200 m. The research findings indicated that an optimal spacing of 5 m and a depth of 150 m were identified. Following a continuous 15-year period of operation, the mean temperature of the soil reached 15.5 °C. This represents a modest increase of just 0.45 °C when compared to the initial soil temperature, demonstrating effective soil temperature recovery and the absence of heat or cold accumulation. This study provides references for the design and construction of double U-shaped buried pipes in the GSHP system.

A novel design of double pipe heat exchanger with innovative turbulator inside the shell-side space

An innovative category of turbulators is implemented within the shell of a double pipe heat exchanger (DPHE). The impact of these turbulators on thermal performance and entropy generation is scrutinized through three-dimensional numerical simulations. Maintaining a constant Reynolds number of 500 for the fluid flowing within the shell, the tube's Reynolds number varies within the range of 3000 to 13,000. However, a simulation is performed with a shell-side/tube-side Reynolds number of 750/13000 to investigate the effects of shell-side Reynolds number on heat transfer. To enhance simulation accuracy, the thermophysical features of water, serving as the working fluid, are defined as temperature-dependent functions. Additionally, structured computational grids, featuring polyhedral cells forming the turbulators, are employed to discretize the solution domain. A notable concordance between the simulations' findings and existing experimental correlations is observed. The outcomes indicate that incorporating this turbulator type includes swirl flows, leading to a discernible enhancement in thermal performance. Specifically, for the case with three turbulators at Retube = 3000, the Nusselt number and pressure loss of the fluid flow within the shell show increments of 73% and 87%, respectively, compared to the conventional DPHE. The performance evaluation criterion (PEC) for the shell-side fluid attains a value of 1.41.

Influence of the twisting and nano fluids on performance of a triangular double tube heat exchanger

Abstract The hydraulic and thermals performance of flow in a double-tube heat exchanger with an inner twisted triangle tube of length L = 1 m has been studied numerically. Equations for energy, turbulence, and Navier–Stokes were used to model the fluid flow and heat transfer in a double-tube heat exchanger with an inner twisted triangle tube. The Reynolds number range was 5000–30,000 for nanofluid (water-Al2O3) as a working fluid under a turbulent flow regime. The considered configuration was examined by varying the volume concentration of nanofluid while keeping the twist ratio constant (Tr = 5). Different cases of volume concentration of nanofluid are triggered (0.05 %, 1 %, 2.5 %, and 4 %, respectively). The numerical outcomes of a double-twisted tube heat exchanger with an inner triangle-twisted tube are validated with the obtainable numerical data. The governing equations were solved with ANSYS Fluent 18.2. The findings reveal that the larger volume concentration of nanofluid (4 %) gives a greater Nusselt number and vice versa due to the increased thermal conductivity of the nanofluid in the double twist tube heat exchanger compared with a plain tube. However, the nanofluid Nusselt number grows with the rise of both the Reynolds number and volume concentration (Ø), and the best value of the Nusselt number is 210 when Reynolds number = 30,000 and Ø = 4 %. The effectiveness of the heat exchanger grows with an increase in the concentration of the nanofluid and a reduction in the torsion ratio compared to the normal tube. The effectiveness of the double-tube heat exchanger with an inner twist triangle tube increases to the highest value of 0.38 at Reynolds 30,000 and Ø = 4 %.

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

Exploring the combined influence of primary and secondary vortex flows on heat transfer enhancement and friction factor in a dimpled configuration twisted tape with double pipe heat exchanger using SiO2 nano fluid

The double-pipe heat exchanger has a wider application in food industries, chemical industries, and a wide variety of fields where heat transmission is necessary. This investigation focuses on optimizing heat transfer rates through active, passive, and combined approaches. Within the realm of passive methods, this study specifically examines the use of twisted tape additions in pipe flow. In this study, different factors like swirl flow, primary and secondary vortex flows caused by tape twist, and the presence of a V-cut on the tape are studied. These factors include heat transfer rate, friction factor, and the standard for judging the performance of a V-cut on the tape insert. Experiments have been conducted on a double-pipe heat exchanger with nanofluid silicon dioxide as the working medium. This study encompasses a Reynolds number range of 6000–14,000. Notably, investigations reveal that the introduction of a v-cut on the tape engenders a secondary vortex flow. The enhancement in the Nusselt number at the higher Reynolds number for the primary vortex was observed ineffective as the depth of cut increases. The friction factor is increased by 6.37 times for the e/c ratio, which equals 0.17 (tooth to the depth of the v cut) in comparison to smooth pipe, while the increase in heat transfer rate for the same is 87.73% for Re = 6000.

Computational Fluid Dynamics Heat Transfer Analysis of Double Pipe Heat Exchanger and Flow Characteristics Using Nanofluid TiO2 with Water

A device called a heat exchanger is used to exchange heat transfer between two fluids with different temperatures. Because of its durability and ability to handle high-pressure application, the concentric double pipe heat exchangers are widely utilized for numerous industrial applications. To conserve pumping power energy, many researchers were involved in study of the nanoparticles to be embedded in the fluid, which will enrich the fluid thermal conductivity and surface area. This article demonstrates the flow characteristics and convective heat transfer of nanofluids containing 0.2, 0.4 and 0.6 of vol% TiO2 nanoparticles dispersed in water under turbulent conditions, which mainly can be used for cooling nuclear reactors applications. Reynolds numbers varying from 4000 to 18,000 are examined numerically. The convective heat transfer coefficient results of the nanofluid agree well against experimental data, which are slightly more than that of base water at 1.94%. The results of the numerical model showed that the convective heat transfer coefficient of nanofluids will increase when the Reynolds and volume fraction increases. By increasing the temperature of the annular hot water, the heat transfer rate will increase, showing no major impact to the convective heat transfer coefficient of nanofluids. A generalised solution predicting the convective heat transfer coefficient for extensive nanoparticle materials is proposed. The conclusion of the empirical equation is tested among published data and the results are highly congruent, confirming the strength of the gamma equation.

Numerical and experimental investigation of heat transfer enhancement in double tube heat exchanger using nail rod inserts

The Double-tube heat exchanger (DTHX) is widely favored across various industries due to its compact size, low maintenance requirements, and ability to operate effectively in high-pressure applications. This study explores methods to enhance heat transfer within a DTHX using both experimental and numerical approaches, specifically by integrating a nail rod insert (NRI). A steel nails rod insert, 1000 mm in length, is introduced into the DTHX, which is subjected to turbulent flows characterized by Reynolds numbers ranging from 3200 to 5700. Three different pitches of NRI (100 mm, 50 mm, and 25 mm) are investigated. The results indicate a significant increase in the Nusselt (Nu) number upon the insertion of nail rods, with further improvements achievable by reducing the pitch length. Particularly noteworthy is the Nu number enhancement ratio for the 25 mm pitch NRI, which is 1.81–1.9 times higher than that for the plain tube. However, it is observed that pressure drop increases in all configurations with NRI due to heightened turbulence and obstruction by the NRI. Among the various pitch lengths, the 25 mm pitch exhibits the highest pressure drop values. Moreover, exergy efficiency is found to improve across all cases with NRI, corresponding to increased heat transfer, with the 25 mm pitch length showing a remarkable 128% improvement. Numerical analysis reveals that the novel insert enhances flow turbulence through the generation of secondary flows, thereby enhancing heat transfer within the DTHX. This study provides a comprehensive analysis, including temperature, velocity, and pressure drop distributions derived from numerical simulations.

Experimental investigation for heat transfer performance of CuO-water nanofluid in a double pipe heat exchanger

Experimental investigation for heat transfer performance of CuO-water nanofluid in a double pipe heat exchanger

Enhancing the efficiency of a double tube heat exchanger via a novel vibrating woven wire turbulator combined with a helical coiled wire; an experimental study

Vibrating turbulators have emerged as innovative methods for enhancing heat transfer in heat exchangers over the past two years. Previous studies have mainly employed string or strip configurations for turbulator construction. In this research, a novel vibrating turbulator, known as the vibrating woven wire turbulator, is introduced to enhance the thermal efficiency of heat exchangers. This study proposes the first-ever application of a turbulator with this unique geometry. This turbulator consists of intertwined metallic wires, providing a lightweight design with a substantial contact surface area for the fluid. Experiments are conducted for Reynolds numbers ranging from 1000 to 8500, covering both laminar and turbulent flow regimes. The findings demonstrate that this turbulator significantly enhances heat transfer by up to 236 %, while only resulting in a marginal increase in pressure drop. This remarkable improvement in heat transfer, while keeping the pressure drop within acceptable limits, gives rise to an impressive thermal enhancement factor (TEF) of 2.45. To achieve an even higher TEF, this study investigates the synergistic combination of the vibrating woven wire turbulator with a helical coiled wire turbulator. Experiments are conducted on coils with diameters ranging from 0.5 to 1.5 mm. The simultaneous utilization of both turbulators leads to a significant improvement in heat transfer coefficient and pressure drop, with an increase of 545 % and 320 %, respectively, resulting in a high TEF of up to 3.13.