Double Exchanger Research Articles

Enhancement of Double-Pipe Heat Exchanger Effectiveness by Using Water- CuO

This study utilized Nanofluid as a cold fluid in evaluating the counter flow double tube heat exchanger, which was one meter long, had an outer diameter of 19 mm, and an inner diameter of 9.5 mm made from copper. Water was the basic fluid, with the size of 40 nm and a volume concentration of (0.5%) and (1%), respectively, of CuO nanoparticles being added. At 2 L/min and 4 L/min and 6 L/min, the Nanofluid flows inside the inner tube. At 20°C, the Nanofluid enters the heat exchanger. The flow of hot water into the heat exchanger is 4 L/min through an annular space with an entry temperature of 65 °C. to achieve better heat exchanger performance, the experimental results will be compared to those obtained when using pure water. The improvement in performance with Nanofluid as a working fluid was discovered during experiment analysis. (40%) maximum heat exchanger effectiveness obtained at Nanofluid flow rate of 2 L/min has (0.5%) volume concentration ,effectiveness (54%) at (1%) a volume concentration.

Study on flow and heat transfer characteristics of Encapsulated Phase Change Material (EPCM) slurry in Double-Pipe Heat Exchanger

Microencapsulated phase change material (MPCM) slurry as a working fluid was numerically investigated for thermal energy conservation systems due to its high heat capacity associated with the PCM. A mathematical model of a double pipe heat exchanger was developed to conduct the numerical analysis based on the Eulerian-Eulerian flow model. During simulation, it was considered that MPCM slurry flows through the inside pipe of the heat exchanger, whereas high-temperature plain water flows at the annulus side of the heat exchanger. The accuracy of the model was verified with experimental data and showed a good agreement. The effect of particle concentration, Reynolds number, and particle diameter was considered to investigate the energy transport characteristics of the MPCM slurry. The results showed that particle concentration significantly affects the heat transfer performance of MPCM slurry, and it promotes pressure drop due to an increase in viscosity. The highest average heat transfer coefficient of the slurry showed at 15% volume fraction; it was also significantly affected by the particle diameter greater than 100 µm. The local heat transfer coefficient of water and MPCM slurries were compared at a Reynolds number of 6838, and PCM-based HTFs showed a higher local heat transfer coefficient. Furthermore, a ratio of h/ΔP was presented to study the energy transport performance of MPCM slurry at different particle concentrations and compared with plain water, and it was found out that 10% volume fraction showed better performance as HTF (Heat Transfer Fluid).

A CFD investigation and heat transfer augmentation of double pipe heat exchanger by employing helical baffles on shell and tube side

The inclusion of baffles in a double pipe heat exchanger is becoming increasingly important as it improves the heat exchanger's performance. The CFD analysis is used in this paper to investigate the performance of double pipe heat exchangers with and without helical baffles on both shell tube sides. The 3-D CFD model was created in Solid Works, and the FloEFD software was used to analyze the conjugate heat transfer between the heat exchanger's tube and shell sides. Heat transfer characteristic like outlet temperature of shell and tube are investigated along with pressure drop on shell and tube side. Based on CFD results of double pipe heat exchanger with helical baffle on both shell side and tube side (Type 4) gives the better results than the other type of heat exchangers with an increased pressure drop than the others, results reveals that Type 4 outlet temperature of shell side is 8% higher and on tube side it is 5.5% higher, also pressure drop on shell side is 12% higher and on tube side it is 42% higher than the other types.

Heat transfer analysis of double tube heat exchanger with wavy inner tube

The effect of the design on the heat transfer is numerically investigated by using the wavy inner tube in a double-pipe heat exchanger. A wavy inner tube was used in the design to give a turbulent effect to the fluid along the inner tube of a double tube heat exchanger. In numerical study, ANSYS 12.0 Fluent code program was used, and the basic protection equations were solved for steady-state, 3-D and turbulent flow conditions. The study was examined at Reynolds numbers ranging from 2700-5300. The obtained results were compared with the experimental data performed under the same conditions. As a result of this comparison, after it was seen that the results obtained from the numerical analysis and the experimental results were compatible with each other, the wave number of the inner tube was increased and analyzed with the ANSYS fluent code program. When the data obtained as a result of the analyzes were evaluated, it was seen that the highest heat transfer was obtained from the 16 wave tube heat exchanger, which has the highest number of waves and under counter flow conditions. The increase in heat transfer increased by 270% compared to the straight tube.

Thermal Performance Investigation of Double Pipe Heat Exchanger Embedded with Extended Surfaces Using Nanofluid Technique as Enhancement

Thermal Performance Investigation of Double Pipe Heat Exchanger Embedded with Extended Surfaces Using Nanofluid Technique as Enhancement

Experimental investigation of thermal potential at diesel engine exhaust and numerical simulation of heat recovery in heat exchangers

The exhaust gas from an internal combustion engine carries away about 30% of the heat of combustion. The energy available in the exit stream of many energy conversion devices goes to waste, if not utilized properly. The major technical constraint that prevents the successful implementation of waste heat recovery is due to its intermittent and time mismatched demand and availability of energy. In this regard, the present work focused on investigating the thermal potential available at the diesel engine exhaust and its utilization for various applications. In this work, experimental investigations have been performed to identify the thermal potential available at diesel engine exhaust for different load conditions. Now to recover the available thermal potential, a double pipe heat exchanger of counter flow type has been modeled in ANSYS Design Modular. The same has been numerically simulated in ANSYS workbench environment to get the outlet temperatures of hot and cold fluids. The results have been evaluated for heat exchanger, operating at engine exhaust temperature of 478 K and cold water temperature of 298 K. Simulation results shows cold outlet temperature as 435.11 K.

An Analytical Model for the Thermal Assessment of a Vertical Double U-Tube Ground-Coupled Heat Pump System in Steady-State Conditions

An analytical model was built to predict the thermal resistance of a vertical double U-tube ground-coupled heat pump that operates under steady-state conditions. It included a geometry obstruction factor for heat transfer throughout the backfill medium due to the presence of the second loop. The verification of the model was achieved by the implementation of five different borehole configurations and a comparison with other correlations in the available literature. The model considered a U-tube spacing range between (2) and (4) times the U-tube outside diameter producing a geometry configuration factor range of (0.29–0.6). The results of the model were utilized for the assessment of the DX ground heat exchanger coupled heat pump system. For similar geometrical configurations, the borehole thermal resistance experienced a decrease as the geometry factor increased. The single U-tube borehole thermal resistance was higher than that of the double U-tube heat exchanger by (10–27)% for the examined geometry configurations. The borehole thermal resistance at tube spacing of twice the tube diameter was higher than the predicted value at the triple diameter and fell in the range of (18–34)%.

Effect of Nanofluids on the Thermal Performance of Double Pipe Heat Exchanger

Effect of Nanofluids on the Thermal Performance of Double Pipe Heat Exchanger

A comprehensive numerical study of energy efficiency analysis of a double pipe gas cooler based on second law analysis

A numerical simulation of energy efficiency in commercially available double pipe heat exchangers in the market was investigated based on the Second law of thermodynamics in this paper. The effects of CO2 mass-flow rate, water mass-flow rate, pressure, CO2 inlet temperature, and water inlet temperature of the double pipe heat exchanger were considered to evaluate the energy efficiency by analyzing entropy generation, exergy destruction, and entransy dissipation. The changes of the entropy generation, the changes of exergy destruction, and entransy dissipation are similar regardless of the operating conditions. Pressure has the most significant effect on the energy efficiency of the double pipe gas cooler compared to other operating conditions but negligible on the exergy destruction. The pressure, flow rate, and inlet temperature have completely different effects on energy efficiency depending on the region. The entropy generation and entransy dissipation at y = 0 m to y = 0.05 m (y-axis is the radial direction) decrease with increasing pressure and the opposite after that. The increase of CO2 inlet temperature at y < 0.5 m is accompanied by an increase of entropy generation, exergy destruction, and entransy dissipation but this situation disappears after y = 0.5 m. Entropy generation, exergy destruction, and CO2 and water mass-flow rate are first negatively and then positively correlated with the cut-off point at y = 0.1 m.

EXPERIMENTAL INVESTIGATION ON HEAT TRANSFER OF Al2O3-MWCNT/WATER-BASED HYBRID NANOFLUIDS IN DOUBLE-PIPE MINI HEAT EXCHANGER: DESIGN OF EXPERIMENTS USING RSM

EXPERIMENTAL INVESTIGATION ON HEAT TRANSFER OF Al2O3-MWCNT/WATER-BASED HYBRID NANOFLUIDS IN DOUBLE-PIPE MINI HEAT EXCHANGER: DESIGN OF EXPERIMENTS USING RSM

Experimental analysis on heat exchanger using Al2O3-CuO hybrid nano coolant

This research work gives the insight on heat transfer performance of nano coolants using hybrid nanoparticles Al2O3-CuO in mixture ratio 20:80, 50:50, 80:20 respectively, at 0.1 vol% of 5 liter base fluid (mono ethylene glycol (MEG)+ deionized water (DW)) on a double pipe shell and tube heat exchanger. Nanoparticles were prepared using ball milling, magnetic stirring and ultra-sonication. The average diameter of crystallites of hybridized nanoparticles was in the range of 25 nm to 35 nm, determined using an X-ray diffractometer. Specific heat capacity, density and kinematic viscosity were determined using differential scanning calorimetry, Redwood viscometer and precision balance, respectively. Modifications were done on the cold side of the heat exchanger by installing a tank at the top for the nano coolant. The flow rates on cold fluid side was fixed to 1.2 L/min and hot fluid side varied from 0.6 L/min to 1.2 L/min operated on both, parallel flow and counter flow arrangement. Coolant sample 80:20 (Al2O3:CuO) amongst all the samples possessed highest rate of effectiveness with an increment of 35% when compared to traditional sample DW + MEG and also with water. Highest logarithmic mean temperature difference (LMTD) and overall heat transfer coefficient (OHTC) were observed for the above sample. Smidgen amount of agglomeration had been observed while conducting the experiment.

W-Cut Twisted Tape's Effect on the Thermal Performance of a Double Pipe Heat Exchanger: A Numerical Study

W-Cut Twisted Tape's Effect on the Thermal Performance of a Double Pipe Heat Exchanger: A Numerical Study

Experimental analysis to study the effect of perforated louvered strip‐coiled spring insert on heat transfer performance in a double pipe heat exchanger

AbstractExperiments have been conducted to study the effect of louvered strip‐coiled spring (PLSCS) turbulators having different pitches and the same angle of attack on thermal performance and pressure drop of a concentric tube heat exchanger. Two inserts in combined form were used for experimentation under turbulent flow at different Reynolds numbers (Re) ranging between 5000 and 20,000. Two pitches (40 mm and 50 mm) of elliptical‐shaped perforated louvered strips (PLS) having the same angles of attack have been taken that were welded on the central core rod. Spring inserts have the same coil diameter of 12 mm with two varying pitches to achieve pitch ratios of 0.5 and 1. Both heat transfer and pressure drop increase with a decrease in pitches of both LS and spring inserts. Nusselt number has the maximum value with spring of pitch 6 mm in combination with a PLS of 40 mm pitch at which is 130.75% higher than the plain tube at the lowest Re among the PLSCS inserts. With perforation, a slight increase in both Nusselt number and friction factor was observed. The maximum thermal performance efficiency value is 1.105 for the lowest Re value.

Experimental and numerical analysis of thermal performance of shape stabilized PCM in a solar thermal collector

A typical solar domestic water heating system suffers from low energy efficiency due to multiple heat transfer process among components, i.e., the solar thermal collector and the thermal energy storage. In this work, a compact design of storage-integrated solar thermal collector and its compatible phase change material (PCM) storage material were explored. The salt hydrate based composite PCM, the sodium acetate trihydrate (SAT), was used to create a shape stabilized PCM (ssPCMs) for a feasible PCM by its low leakage and high thermal conductivity. The developed ssPCMs has been tested experimentally and a numerical model has been developed to obtain the effective thermal property of the developed ssPCMs by comparing the predicted results with the measurements. Furthermore, the model has been used to study the (dis)charging behavior of PCM in a storage-integrated solar thermal collector which is composed of an evacuated tube and a double spiral coils heat exchanger. A geometrical optimization has been performed to achieve 2.6 times longer of discharging period with a minimum outlet temperature of 55 °C. Moreover, the circulating water is found useful in increasing the PCM charging rate with 9% by transferring the heat from the surface to the center of tube.

Enhancement of heat transfer of double tube heat exchanger with inner twisted spiral tube

Enhancement of heat transfer of double tube heat exchanger with inner twisted spiral tube

Experimental and CFD Analysis of GW70 based Cu Nanofluids in a Parallel Flow Heat Exchanger

The Nusselt number, overall heat transfer, and convective heat transfer coefficients of glycerol-water-based Cu nanofluids flowing in a parallel flow double pipe heat exchanger are estimated using CFD analysis. Single-phase fluid approach technique is used in the analysis. Ansys 19.0 workbench was used to create the heat exchanger model. Heat transfer tests with nanofluids at three flow rates (680<Re<1900) are carried out in a laminar developing flow zone. For testing, a 500 mm long concentric double pipe heat exchanger with tube dimensions of ID=10.2 mm, OD= 12.7 mm, and annulus dimensions of ID=17.0 mm, OD= 19.5 mm is employed. Copper is utilized for the tube and annulus material. This study employed three-particle volume concentrations of 0.2 percent, 0.6 percent, and 1.0 percent. The mass flow rates of hot water in the tube are 0.2, 0.017, and 0.0085 kg/s, while the mass flow rates of nanofluids in the annulus are 0.03, 0.0255, and 0.017 kg/s. The average temperature of nanofluids is 36°C, whereas hot water is 58°C. In comparison to base liquid, the overall heat transfer coefficient and convective HTC of 1.0 percent copper nanofluids at 0.03 kg/s are raised by 26.2 and 46.2 percent, respectively. The experimental findings are compared to CFD values, and they are in close agreement.

Analysis of fluid retention zones in heat exchangers with segmental baffle and helical baffle

Abstract By using the residence time distribution method (RTD), the fluid retention zones in the shell and tube heat exchanger with segmental baffle (STHX-SB) and the heat exchanger with helical baffle (STHX-HB) are compared and discussed. The flow pattern and fluid retention zone of the similar double helical flow heat exchanger (STHX-SDH) were analyzed by using the same method. The result shows the spiral flow can reduce the fluid retention zone. The flow pattern in the STHX-SDH likes a double helical shape and leads to a very small fluid retention zone. According to the simulation results, the location of the fluid retention zone of STHX-SDH is determined. The verification line method and the zone assessment method were adopted, to discuss the flow velocity of each point on the verification line and the average flow velocities of the selected zones. The change laws of the flow velocities on the verification lines and the average flow velocities of the selected zones at different Reynolds numbers were compared. The result reveals the distribution of the fluid retention zone of the STHX-SDH and the sensitivity of each fluid retention zone to the Reynolds number. By optimization of the angle of the baffle, the volume fraction of the fluid retention zone is reduced to 1.61%, and the heat transfer performance is improved by 13.23%. It is verified that reducing the fluid retention zone can effectively enhance the heat transfer performance. This research method provides a theoretical basis for reducing the fluid retention zone of the heat exchanger and enhancing heat transfer performance.

Heat transfer enhancement in a double pipe heat exchanger with copper oxide nanofluid: An experimental study

This study aims to see how copper oxide nanofluids affect heat transfer enhancement in a double-pipe heat exchanger at various temperatures. At different inlet temperatures, copper oxide nanoparticles with a concentration of 0.004% by volume were used. According to the findings of the study, thermal performance increases as the thermal and volume concentration of nanoparticles rises. An enormous number of studies have currently been conducted to assess the consequence of nanofluid on the thermal performance enhancement in the double pipe heat exchanger. The type of nanoparticles, their size, shape, the kind of base fluid, and the concentration of nanoparticles in the base fluid all play a role in heat transfer enhancement utilizing nanofluid. This paper looks at how the heat transfer physiognomies of a double pipe heat exchanger are affected by different amounts of CuO nanoparticles mixed in water.

Experimental investigation of heat transfer and pressure drop characteristics of internal finned tubes

This study investigates experimentally laminar flow in a water-to-water double pipe heat exchanger for counter flow arrangement. The hot water flows in inner pipe and cold water in the outer annulus. The test section, which has a length of 1400 mm, is a horizontal annular passage formed by aluminum alloy tube with an inner diameter 20.9 mm and outer diameter 35 mm. Three different finned tubes with four, six, and eight longitudinal trapezoidal fins, which have length 1400 mm, height 5.23 mm, and thickness 3.63 mm at base and 1 mm at the tip, attached to the wall surface of the inner tube. For comparison, the heat transfer and pressure drop characteristics are also studied for a smooth inner tube. The results show that the differences in Nu are insignificant among the internal finned tubes with four, six, and eight fins at a smaller Re, whereas the inner tube with more fins has a larger Nu at a larger Re. At a fixed Reynolds number, the friction factor of tube with eight fins is the largest, followed by tube with six fins, tube with four fins and smooth tube for Re< 1000; however, the differences in friction factors of the four heat exchangers are not pronounced for Re >1500. In addition, the heat transfer benefit tends to decrease as the pressure drop increases for internal finned tubes. Finally, empirical correlations of Nusselt number and the friction factor with the Reynolds number are proposed.

Multi-objective optimum design for double baffle heat exchangers

The enhancement of the heat transfer rate of heat exchangers with a lower-pressure drop in passing fluid flow always was a consideration and challenging purpose for researchers. Increasing industrial equipment efficiency is a crucial problem for engineers. A multi-objective optimal design in order to increase heat transfer rate and low-pressure drop in a two-dimensional baffle heat exchanger considering turbulent fluid flow in a channel is presented. The genetic algorithm is utilized for obtaining an optimum arrangement of two flat-plate for satisfying mentioned purposes. The image processing method is used for detecting the edges of the mounted baffles and the appropriate mesh configuration is generated for the solution domain. Turbulent fluid flow and energy equations are discretized and solved over the physical domain by the finite volume method. The combination of genetic algorithm and image processing method with computational fluid dynamics provides an accurate new approach for optimization targets that is investigated in the present study. All generated baffles dimensions by the genetic algorithm are evaluated to achieve the design with an optimum value of a liner scaled function of two target parameters (i.e. temperature and pressure variations of the passing fluid flow through the channel). Investigating the results of all the generated and evaluated designs obtains the Pareto’s front in addition to the optimum design for these target parameters. For a case study with the same importance for the pressure drop (in Pa) and the passing fluid temperature increment (in K), the optimum baffles arrangement, with two 2 cm height baffles with 22 cm distance, shows a suitable heat transfer rate (ΔT = 32.04 K) and a low-pressure drop (ΔP = 3.007 kPa) for the passing fluid flow. All the possible optimum designs for this double baffles heat exchanger, with different importance of ΔT and ΔP, are obtained using the Pareto method.