Coil Heat Exchanger Research Articles

Numerical investigation of coupled heat transfer and flow characteristics in helical coil heat exchanger for mine water waste heat recovery

To efficiently recover waste heat from mine water, this study numerically investigates the flow and heat transfer performance of a tube-shell coupled helical coil heat exchanger (HCHE), under high Reynolds number conditions. The effects of inlet water temperature, mass flow rate (m), tube diameter (d), and helix pitch (P) on the tube side, shell side, and overall performance are analyzed. Performance metrics include friction factor (f), Nusselt number (Nu), overall heat transfer coefficient (U), heat transfer rate, and the Performance Evaluation Criteria (PEC) number. Specifically, this study focuses on detailed observation and analysis of the shell-side flow and temperature fields. Findings reveal that enlarging d from 30 mm to 50 mm results in a 32.55% decrease in U, whereas increasing P from 50 mm to 200 mm boosts U by 8.02%. The highest PEC number of HCHE is 2.43, observed in conditions of P = 50 mm, d = 30 mm, and mc = 4 × 103 kg/h. Correlations for fc, Nuc, and Nush are proposed based on simulation results. This study provides a theoretical basis for the design and structural optimization of HCHE in the mine water waste heat recovery applications.

Transient evolution of thermal stratification and passive flow guidance inside a heat exchanger immersed thermal energy storage tank

Thermal stratification is being studied globally for thermal storage tanks while natural convection motion has a high impact on the phenomenon. Therefore, in this work, a conical guide geometry is introduced as a passive flow modifier to enhance the thermal stratification inside a cylindrical tank that is used for thermal storage purposes. The tank also has an immersed spiral coil heat exchanger in it. Transient evolution of thermal stratification inside the thermal storage tank is monitored for different charge flowrates and temperatures. The experimental data is used to benchmark a commercial computational fluid dynamics code relying on finite volume method. After seeing that the code simulates the transient thermal stratification with acceptable discrepancies, a conical guide geometry above the immersed heat exchanger is examined via the computational code for dimensional variations. The dimensions of the cone guide are defined based on thermal storage tank dimensions in order to have some degree of universality. The best performing cone guide in the simulations is then tested experimentally. It is validated that the proposed cone guidance enhanced thermal stratification evolution in the tank. An increase of 3.85 °C is obtained in the average tank temperature with the use of the cone guide after 3 h of charging. Approximate effectiveness of the heat exchanger coil is found about 90 % while a 7.6 % increase is realized by the utilization of the guide.

Atomic Force Microscopy Study of the Long-Term Effect of the Glycerol Flow, Stopped in a Coiled Heat Exchanger, on Horseradish Peroxidase.

Glycerol is employed as a functional component of heat-transfer fluids, which are of use in both bioreactors and various biosensor devices. At the same time, flowing glycerol was reported to cause considerable triboelectric effects. Herein, by using atomic force microscopy (AFM), we have revealed the long-term effect of glycerol flow, stopped in a ground-shielded coiled heat exchanger, on horseradish peroxidase (HRP) adsorption on mica. Namely, the solution of HRP was incubated in the vicinity of the side of the cylindrical coil with stopped glycerol flow, and then HRP was adsorbed from this solution onto a mica substrate. This incubation has been found to markedly increase the content of aggregated enzyme on mica-as compared with the control enzyme sample. We explain the phenomenon observed by the influence of triboelectrically induced electromagnetic fields of non-trivial topology. The results reported should be further considered in the development of flow-based heat exchangers of biosensors and bioreactors intended for operation with enzymes.

Design and experimental analysis of a cooling system with erythritol/xylitol PCM thermal energy storage

The erythritol/xylitol eutectic phase-change material has strong potential applications in the field of thermal management. In this study, we propose a cooling system for high-power electronic devices that combined a closed water loop and Latent Heat Thermal Energy Storage (LHTES). The LHTES features double helical coil heat exchange tubes, using erythritol/xylitol as the PCM. A test platform was constructed to evaluate heat transfer performance. During the charging phase, the high-power, high-heat flux heater was cooled using a microchannel cold plate. The heat generated by the heater was transferred to the LHTES. In the discharging phase, the heater was turned off, and the heat stored in LHTES was released, achieving the regeneration of the PCM. Based on our previous work, a method involving gas and seeding injection was employed during the discharging process to trigger secondary nucleation. The helical heat exchange coil not only exhibited good heat exchange performance but also provideed sufficient gas pathways, allowing injected bubbles to create ample disturbance. This ensured thorough mixing of seeding particles with supercooled liquid. The total heat storage capacity of the heat storage unit was 10 MJ, achieving a maximum cooling power of 310 W. The impact of different operational parameters was examined, including water flow rate and heating power during the charging process, and the effects of gas and seed crystal injection, cooling fan speed, and water flow rate during the discharging process. An automated control system was established to optimize the cooling system's operation. This study facilitates the practical engineering application of erythritol/xylitol eutectic PCM.

Effects of an Annular Baffle on Heat Transfer to an Immersed Coil Heat Exchanger in Thermally Stratified Tanks

Abstract The effect of a cylindrical baffle on heat transfer to an immersed heat exchanger is investigated in initially thermally stratified tanks. The heat exchanger is located in the annular region created by the baffle and the tank wall. Three different cases of initial thermal stratification are explored, and in each case, experiments are conducted with and without the baffle in the stratified tank and in a comparable isothermal tank with the same initial energy, enabling exploration of the role of the baffle in a stratified tank and the role of stratification in tanks with or without the baffle. The baffle maintains the high initial temperature of the upper zone of the stratified tank for 10–16 min, as cool plumes that form on the heat exchanger are confined to the annular baffle region until they exit at the bottom of the tank. Regardless of stratification, the baffle always improves heat transfer to the immersed heat exchanger. In the isothermal tanks, the baffle increases total energy extracted in the first 30 min of discharge by over 20%. In stratified tanks, the baffle increases total energy extracted in 30 min of discharge by 9–16%. Initially, improvement in heat transfer in stratified tanks is due to the higher driving temperature differences around the heat exchanger. Later, after all the water from the hot zone has entered and flowed through the baffle, the tank is basically isothermal, and velocity increases as the fluid temperature drops, maintaining rates of heat transfer higher than that in the tank without the baffle. Stratification improves heat transfer in tanks without a baffle because, by design, the driving temperature difference between the heat exchanger wall and the surrounding fluid is considerably higher. However, in tanks with the baffle, stratification has only a modest positive effect on heat transfer to the immersed heat exchanger.

Novel integration of thermoelectric distiller with direct contact membrane distillation

A thermoelectric distiller (TED) integrated with a direct contact membrane distillation (DCMD) unit was proposed and numerically investigated. The mathematical models of the hybrid TED--–DCMD system were developed and validated. In the proposed hybrid system, the TED provides the heating demand of the DCMD desalination unit in four novel configurations of TED-DCMD integration. The first configuration integrates the TED-DCMD by adding a DCMD heat exchanger coil inside the condensation tank of a TED, while the second configuration involves two TED condensation tanks with each tank containing a DCMD heat exchanger coil. The third configuration also consists of two TED tanks with an external heat exchanger where thermal energy from the TED produced water is transferred to the DCMD feed stream. The fourth configuration is a modification of the second configuration with a thermal recovery from TED produced water for inlet feed water preheating. To investigate the performance (distillate productivity, specific energy consumption, coefficient of performance, and ratio of TED productivity) of each integrated TED-DCMD configuration, the effects of different operating parameters such as DCMD feed flow rate, TEM current, number of TEMs, and TED produced water temperature were examined. Findings indicated that the third configuration is the most energy efficient, with specific energy consumption (SEC) reaching a minimum value of 217 kWh/m3 at low current operation of 2.1 A, and feed flow rate of 4.0 L/min for 8.0 TEMs in the TED. A maximum freshwater productivity and COPh of 2.74 kg/s and 3.24, are attained by the 4th and 3rd configurations, respectively. Results also indicated that elevating the current input encourages higher water productivity. Meanwhile, higher values of SEC and water productivity are attained when operating TED at saturation temperature.

Numerical research of an internal and external-corrugated tube-in-tube helical coil heat exchanger

ABSTRACT To effectively enhance the heat transfer of a tube-in-tube helical coil heat exchanger, a novel internal and external-corrugated tube-in-tube helical coil was proposed by improving both the inner and outer tubes. The impact of the corrugation layout on the annular region’s heat transfer property was simulated. The effect of periodically distributed corrugations on flow patterns and the local Nusselt on the inner tube wall was explored. Furthermore, by comparing the fluid’s velocity and temperature field contour in traditional helical coil and novel helical coil, the enhanced heat transfer mechanism was discovered. Finally, the effects of Re, dimensionless depth H, and dimensionless pitch S of corrugations on the annular region’s heat transfer, flow resistance and entropy generation were analyzed. The results showed that annular region’s heat transfer could be improved due to the periodically distributed corrugations. The local Nu distribution on the corrugated inner tube wall was similar to that of ordinary inner tube, while changed periodically due to the continuous influence of corrugations. The number of Nu and f increased by 53% ~72% and 40% ~120% with the dimensionless corrugation depth and dimensionless pitch being 0.15 and 1.5, respectively. The comprehensive heat transfer performance PEC reached 1.2 ~ 1.6, and cross-arranged inner and outer tube corrugations were more favorable for heat transfer than the corresponding arrangement, when Re = 6000, H3 structure has the highest S t , S f and S gen , which are 0.934W/K, 0.379 W/K and 1.312W/K, respectively. Increasing H and decreasing S could enhance the Nu, f and entropy generation. The values of PEC decreased with increasing S, while with the increment of H, PEC increased and decreased, respectively when Re was in the range of (2000, 4000) and (4000, 6000). In the study range, changing H and S could increase Nu by 40.3%–97.3%, 31.7%–96.8%, and f by 11.7%–176.5%, 16.4%–180.9%, respectively. The final comprehensive heat transfer performance increased by 12.8%-65.9%. Finally, the prediction correlation formulas of Nu and f in NTTHC annular region with high correlation is proposed.

Energy matrices, enviro-economic and characteristic equation-based performance analyses of photovoltaic thermal compound parabolic concentrator (PVT-CPC) coupled solar still equipped with heat exchanger using SWCNTs and MWCNTs–water nanofluids

In this paper, effect of single wall carbon nanotubes (SWCNTs) and multiwall carbon nanotubes (MWCNTs)- water based nanofluid have been studied to examine the performance, long-term feasibility andenviro-enviro-economic analysis of partially covered series connected N- photovoltaic thermal (PVT)-compound parabolic concentrator (CPC) collectors coupled double slope solar still (DSSS) equipped with helically coiled heat exchanger (HE). Analysis have been carried out by developing thermal modelling of the proposed system. Instantaneous gain and loss efficiencies; annual thermal energy/exergy, and productivity – is investigated for optimized parameters of the proposed system in detail. Gain efficiency of the proposed system is found to be approximately 25-30% higher using CNT-NPs as compared to the system without using NPs. Annual thermal energy and exergy of CNTs, particularly SWCNTs water-based nanofluid (thermal energy- 2491.55 kWh, thermal exergy-894.67 kWh) have been found to be greater in comparison to basefluid (thermal energy -2185.76 kWh, thermal exergy-772.18 kWh). Also, results give higher value of CO2 mitigation using CNT-NPs both on the basis of energy (SWCNT-5.082t, MWCNT-4.787t) and exergy (SWCNT-1.83t, MWCNT-1.76t) respectively. SWCNT-NPs shows better performance due to their better TPPs; also PVT-CPC collector integrated DSSS equipped with HE is more viable practically.

Mathematical Modelling and Design of Helical Coil Heat Exchanger for Production of Hot Air for Fluidized Bed Dryer

Mathematical Modelling and Design of Helical Coil Heat Exchanger for Production of Hot Air for Fluidized Bed Dryer

Numerical Study of Flow and Heat Transfer Characteristics for Al2O3 Nanofluid in a Double-Pipe Helical Coil Heat Exchanger.

To numerically investigate the flow and heat transfer characteristics of a water/Al2O3 nanofluid in a double-pipe helical coil heat exchanger, we simulated a two-phase Eulerian model to predict the heat transfer coefficient, Nusselt number, and pressure drop at various concentrations (i.e., volume fraction) and under diverse flow rates at the steady state. In this simulation, we used the k-epsilon turbulence model with an enhanced wall treatment method. The performance factor of the nanofluid was evaluated by accounting for the heat transfer and pressure drop characteristics. As a result, the heat transfer was enhanced by increasing the nanofluid concentration. The 1.0 vol.% nanofluid (i.e., the highest concentration) showed a heat transfer coefficient 1.43 times greater than water and a Nusselt number of 1.38 times greater than water. The pressure drop of nanofluids was greater than that of water due to the increased density and viscosity induced using nanoparticles. Based on the relationship between the Nusselt number and pressure drop, the 1.0 vol.% nanofluid was calculated to have a performance factor of 1.4 relative to water, indicating that the enhancement rate in heat transfer performance was greater than that in the pressure drop. In conclusion, the Al2O3 nanofluid shows potential as an enhanced working fluid in diverse heat transfer applications.

The efficacy of carbon molecular sieve and solid amine for CO2 separation from a simulated wet flue gas by an internally heated/cooled temperature swing adsorption process

Considering that most sources of carbon dioxide (CO2) emissions are also waste heat sources, CO2 recovery using self–generated low–temperature waste heat is desirable. This study examines CO2 enrichment and recovery via a temperature swing adsorption (TSA) process. The low–temperature heating–driven TSA process requires an alternative regeneration method to conventional air heating to avoid dilution of the desorbed CO2, and to apply it to actual gas, using an adsorbent that does not lose its CO2 adsorption capacity because of coexisting water vapor is necessary. Zeolites tested in our previous study lose their CO2 adsorption ability under a humid feed gas and a low–temperature regeneration condition. For the former, efficacy of an internally heated and cooled adsorbent–packed fin–coil heat exchanger has been confirmed. This study thus attempts to overcome the latter issue by employing carbon molecular sieve (CMS) and solid–supported polyethyleneimine (PEI) as CO2 adsorbents. The effects of moisture in the inlet gas on the separation performance of adsorbents were investigated. The study reveals that PEI required moisture to extend for CO2 adsorption, and CO2 separation performance increased with higher humidity. PEI can produce the desorbed gas with a CO2 concentration of ∼ 45 % and a recovery ratio of ∼ 70 % from feed gas (CO2 concentration of ∼ 10 %) at a dew point temperature of 15 °C. Conversely, the CMS separation performance is almost independent of humidity. The desorbed gas of CMS indicates a CO2 concentration of only ∼ 30 % and a recovery of ∼ 30 %. The flow of the volumetric desorbed gases and the CO2 concentration rate indicates that CMS has the potential for reducing heat consumption by shortening the regeneration time because most of the CO2 desorbs during the early regeneration step. For increasing the concentration of recovered CO2, a severe control valve is required to eliminate the desorbed nitrogen (N2) accompanied by CO2. In contrast, CO2 desorption from PEI is slower than that in CMS, and PEI needs a relatively longer regeneration time.

Effect of Water-Based Nanofluids on the Generation of Entropy in a Shell and Helical Coil Heat Exchanger

A forced convection finding proves that entropy was generated as a result of the heat transfer between the fluids on the coil and the fluids on the shell side. It was found that entropy generation was affected by nanofluid concentration, coil-side fluid flow rate, shell-side fluid temperature, and agitator speed (500 rpm, 1000 rpm, and 1500 rpm) in this paper. The nanoparticle (Al2O3, CuO, and TiO2) weight fractions ranged from 0.3 to 2%. This paper investigates the friction entropy generation rate, the entropy generation ratio, and the thermal entropy generation rate of various nanofluids in laminar and turbulent flow conditions, using existing correlations to guide the investigation. The results revealed that the generation of entropy increased as the Dean number, SS, and fluid temperature on the shell side of the reactor were increased in the laboratory. And, found that the maximum entropy generation rate of Al2O3/water, CuO/water, and TiO2/water nanofluids occurred at 56.4 percent by weight of the nanofluid, 62.1 percent by weight of the nanofluid, and 48.1 percent by weight of the nanofluid.

CFD simulation of helical coil heat exchanger with Different coil pitch to heating heavy fuel oil

CFD simulation of helical coil heat exchanger with Different coil pitch to heating heavy fuel oil

Heat and mass transfer of a novel CO2 desorption process integrated with highly turbulent catalytic heat exchanger

This was the first work that pioneered the development a novel catalytic CO2 desorption process using an agitated jacket vessel with a coil heat exchanger (JVC) into a bench-scale pilot plant for post-combustion carbon capture technology. The key parameters of heat and mass transport e.g., overall heat transfer coefficient, overall volumetric liquid-side mass transfer coefficient and the enhancement factor for catalyst effect, were experimentally investigated by varying the operating conditions, including temperature, stirring speed, and heating methods. The proposed investigations revealed that the utilization of the JVC was a promising technology for improving heat transfer and mass transfer performance in the desorption process due to the high turbulence flow and more favorable thermal distributions achieved by the JVC. In comparison to the conventional process with a fixed catalyst bed, the JVC demonstrated a remarkable approximately 30 % catalytic enhancement and a substantial 50 % reduction in catalyst demand. Additionally, other potential benefits and challenges of further practical operations were discussed in this paper. This research carried significant potential to contribute to the advancement of knowledge and offer valuable insights into the practicability of the catalytic desorption process for further commercial application in carbon capture. The integration of catalyst and JVC could potentially motivate the utilization of catalyst towards commercial-scale applications.

Heat transfer in helical coil heat exchanger: An experimental parametric study

Heat transfer in helical coil heat exchanger: An experimental parametric study

Enhancement of heat transfer in helical coil heat exchangers using nano-fluids

Enhancement of heat transfer in helical coil heat exchangers using nano-fluids

Radiation heat transfer of hybrid nanofluid stagnation point flow across a stretching porous cylinder

The current study provides a comprehensive analysis of MHD hybrid nanofluids and stagnation point flow toward a porous stretched cylinder in the presence of thermal radiation. Here, alumina and copper are considered the hybrid nanoparticles, while water is the base fluid. To begin, the required similarity transformations are applied to transform the nonlinear coupled PDEs into nonlinear coupled ODEs. The obtained highly nonlinear sets of ODEs are then solved analytically by using the HAM procedure. The calculations of the thermal radiation term in the energy equation are done based on the Roseland approximation. The result of various embedded variables on temperature and velocity profiles is drawn and explained briefly. Aside from that, the numerical solution of well-known physical quantities, like skin frictions and the Nusselt number, is computed by means of tables for the modification of the relevant parameter. The analysis shows that the magnetic field has opposite behavior on and profiles. It is seen that more magnetic factor M decline and upsurge . Moreover, the behavior of skin friction and the Nusselt number are same for the magnetic parameter M. Meanwhile, a higher Reynolds number declines temperature profile and skin friction while upsurge the local Nusselt number. There are many applications of this study that are not limited to engineering and manufacturing, such as polymer industry, crystal growth, tumor therapy, plasma, fusing metal in electric heaters, nuclear reactors, asthma treatment, gastric medication, cooling of atomic systems, electrolytic biomedicine, helical coil heat exchangers, axial fan design, polymer industry, plane counter jets, and solar collectors.

Computational Analysis of Thermal Performance Augmentation in Helical Coil Heat Exchangers via CuO/Water Nanofluid

Computational Analysis of Thermal Performance Augmentation in Helical Coil Heat Exchangers via CuO/Water Nanofluid

Experimental and Numerical Investigations on the Heat Transfer of a Helical Coil Heat Exchanger Utilized α-Al2 O3 nanofluid

This study focused on investigating the impact of α-Al2O3 nanoparticles on heat transfer in shell and helical coiled tube heat exchangers. The objective was to analyze the influence of various geometrical characteristics, specifically the coil pitch, on the Nusselt numbers of both sides using a combination of numerical simulations and experimental methods. The working fluid for the hot side was water. The research encompassed an examination of the friction factor for three different coils, exploring the effects of pitch spacing on heat transfer, and assessing the influence of nanoparticles on heat transfer on the inner side of the coil. The findings of the current work indicated significant improvements in heat transfer parameters when employing water-α-Al2O3 nanoparticles as the cold fluid. Comparing this heat exchanger to one without the inclusion of α-Al2O3 nanoparticles revealed a remarkable efficiency enhancement of 7.68 percent. This increase strongly suggests a notable acceleration in the rate of heat transmission within the heat exchanger. Overall, this study provides valuable insights into the utilization of α-Al2O3 nanoparticles in enhancing heat transfer in shell and helical coiled tube heat exchangers. The results highlight the potential benefits of incorporating nanoparticles into such systems, leading to improved performance and more efficient heat exchange processes.

Design of a universal apparatus for heat treatment of meat and vegetable cooked and smoked products with the addition of dried semi-finished products of a high degree of readiness to the recipe

The object of the study is the process of smoking a molded meat-vegetable product with the addition of a dried semi-finished product of a high degree of readiness based on Jerusalem artichoke, zucchini, and carrots. Combined health products will satisfy the demand of end users for functional products of the new generation and will solve the technological problems of manufacturers in accordance with European competitiveness procedures. They will expand the offer of products with rational nutritional, taste, aesthetic characteristics that will meet the modern trends of craft producers, NoReCa business, and consumer expectations. A universal device for heat treatment of meat and vegetable products under hot and cold smoking conditions has been designed based on a film-like resistive electric heater of the radiating type. The device uses Peltier elements placed on the outer surface of the smoke generator and, at a temperature of 45 °C, they form a low-voltage power supply (~3...4 W) from the conversion of secondary heat. Cold smoking is carried out in the temperature range up to 25 °С, provided that the outer surface of the heater is covered with a coil heat exchanger through which the coolant passes. During hot smoking, the air medium is in the heat exchanger (additional thermal insulation of the chamber). The uniformity of the temperature field of the meat-vegetable product (meatloaf with a diameter of 0.08±0.01 m) during hot smoking has been confirmed, provided that the center of the loaf reaches 65 °C and the total duration of the process is 5.5 hours. The introduction of dried semi-finished products of a high degree of readiness into the recipe of meat loaves increases the yield of the product by 18 % and the mass fraction of protein by 25 %. The moisture retention capacity of the experimental meat product increases by 11 % with a 33 % decrease in calorie content, which indicates an improvement in its quality indicators compared to the analog