Tube Counter Flow Heat Exchanger Research Articles

Numerical investigation on Double Tube Counter Flow Heat Exchanger

In the current study, the investigation of heat transfer and fluid flow Characteristics of Pure water when pass through a double tube heat exchanger (DTHX). this investigation has been conducted across various Reynolds Number to gain insights into their performance also conducted a computational fluid dynamics (CFD) simulation using the ANSYS-FLUENT 22 R1 software. Result obtained was validated by comparing to empirical correlation data found in the existing literature. The investigation considered various operating variable as Reynolds Number and temperature across the inner, and outer tubes. Specifically, the Reynolds Number of a range of 2500 to 5500 at 333 K, and 2500 at 303 K for the respective tubes. Key findings are that friction factor is increase by 6.38% as compared to correlation (Blasius) in existing literature. And Nusselt number (Nu) increase by 40.84% as compared to correlation at the Reynolds Number (Re) of 2500. The heat transfer coefficients (hi) were increased by 8.30% as compared to existing literature.

Experimental study of the impact of low concentration MgO-distilled water nanofluid on thermal performance of concentric tube counter flow heat exchanger

Experimental study of the impact of low concentration MgO-distilled water nanofluid on thermal performance of concentric tube counter flow heat exchanger

Experimental and numerical investigation of thermo-hydrodynamic performance of twin tube counter flow heat exchanger using cerium oxide nanofluid

This study accomplished experimental and numerical investigations regarding cerium oxide (CeO2) nanofluid. The aim of this study is to estimate the thermo-hydrodynamic performance of twin tube counter flow heat exchangers (TTCFHEs) in the presence of CeO2 nanofluid. The CeO2 nanofluid concentrations varied from 0.1% to 0.3% by volume. In TTCFHEs, the mass flow rates of cold fluid flow varied from 3 LPM to 15 LPM (i.e. Reynolds number, Re varied from 2436 to 11,626). At the same time, hot fluid flows inside the shell at a constant mass flow rate of 6 LPM. For the numerical investigations, the standard k-ɛ model is adopted for the turbulent flow regimes, where the Reynolds number is varied from 2436 to 11,626. For validation purpose, the present numerical study and experimental data are matched with the correlations available in the literature. Further, numerical result of the Nusslet number is well agreed with the experimentally recorded data with a deviation less than 10%. From the study, it is witnessed that the outlet temperature of the cold fluid increases and decreases with increasing the concentrations of CeO2 nanofluids and with increasing the flow Reynolds number, respectively. On account of 0.3% and 0.2% CeO2 nanofluid, the average Nusselt number (Nu) showed almost 43.35% and 30.13% greater than that of base fluid with a moderate increase in the pressure drop in the range of mass flow rate is considered. However, from the numerical investigations, the performance evaluation criteria (PEC) increases with increasing nanofluid concentrations. At higher concentrations (i.e. 0.3%) of CeO2 nanofluid, the average PEC showed 16.65% higher than the 0.1% CeO2 nanofluid with a marginal increase in the pressure drop.

KINERJA GAS PENUKAR PANAS ALIRAN BALIK SHELL AND TUBE UNTUK PENGERING PERTANIAN

Abstract—One of the important post-harvest processes of rice is drying. Drying is divided into two, namely natural drying (using sunlight) and artificial drying (using tools). In this study drying utilizes heat from a biomass furnace and a configuration of heat exchanger pipes. Where the utilization of heat and the configuration of heat exchanger pipes in the design can increase thermal efficiency because the exhaust hot air mixed with smoke can still be used for drying. The configuration of the heat exchanger pipe greatly influences the expected moisture content level. The purpose of this study was carried out to determine the performance of the shell and tube counter flow heat exchanger for agricultural dryer gases with a heat source from biomass and to find the effect of the configuration of the heat exchanger pipe arrangement on the working process of the drying machine. This research is an experimental test of the performance of heat exchange pipes with a heat source from a biomass furnace. The exchange pipe performance parameters that must be known are temperature and time. The method used in this study refers to experimental and descriptive methods, namely research conducted in a systematic, factual and accurate manner. The results of this study are that the heated air flow rate affects LMTD, heated air outlet temperature, heat transfer coefficient, and efficiency, with variations in the heated air flow rate of 0.11 kg/s, 0.16 kg/s, 0.20kg/s, 0.24kg/s. Highest efficiency of 94% at a heated air flow rate of 0.24 kg/s. and the smallest efficiency of 74% is found in the value of the heated air flow rate of 0.11 kg/s.
 Keywords : dewatering, biomass, pipe configuration, heat exchanger pipe

CFD analysis of heat transfer enhancement in a concentric tube counter flow heat exchanger using nanofluids (SiO2/H2O, Al2O3/H2O, CNTs/H2O) and twisted tape turbulators

A concentric tube, counter flow heat exchanger with nanofluids under turbulent flow conditions has been examined using a computational fluid dynamics model. The proposed model consists of Twisted Tape Turbulators (TTT) on the annular side and inside the tube along with different nanofluids. Twisted Tape Turbulators produce a swirl motion within the fluids to increase heat transfer. Al2O3/H2O, SiO2/ H2O, and CNTS/ H2O nanofluids (with varying volume concentrations of 1 %, 2 %, and 3 %) with the turbulent flow (Reynold number Re = 2000 to 10000) were considered to determine three major parameters i.e., heat transfer rate (Q), overall heat transfer coefficient (U) and Nusselt number (Nu). This study resulted in 6.03 %, 16.74 %, and 6.74 % enhancement of overall heat transfer coefficient (U) with a 3 % volume concentration of CNTS/H2O nanofluid, Al2O3/H2O nanofluid, and SiO2/H2O nanofluid, respectively, when equated to without twisted tape tabulators. This analysis shows the maximum value of Nusselt number as 143,136.68 and 140.12 for CNTS/H2O, Al2O3/H2O, and SiO2/H2O, respectively, for the twisted tape tubular arrangement. It is concluded that when using twisted tape turbulator, the heat transfer rate (Q), overall heat transfer coefficient (U), and Nusselt Number (Nu) increase with increasing Reynolds number (turbulent flow conditions) and volume concentrations of nanofluid.Novelty statement: Twisted Tape Turbulators (TTT) arrangement with different concentrations and types of nanofluids combined are infrequent in the study of concentric tube heat exchanger with turbulent flow to obtain enhanced heat transfer.

Enhancement of Heat Transfer in a Concentric Tube Counter Flow Heat Exchanger using CuO Nanofluids

Engineers and Scientists have always tried to increase the rate of heat transfer. The most commonly used base fluids do not provide a very high rate of heat transfer. This research work aims to investigate the enhancement of heat transfer rate in a concentric type (double pipe) counter flow heat exchanger using CuO nanofluids at different volume concentrations (0.01%, 0.05% and 0.1%). The experiments conducted on nanofluids showed that, at 0.1% volume concentration of nanofluid at 2.5 LPM, the heat transfer rate, Reynolds’s number and effectiveness were increased by 16.25%, 15.52% and 2.88% respectively compared to base fluid without nano-particles. Hence it was concluded that, CuO nanofluid is having a great potential to be used as a better heat transfer fluid in heat exchangers.

Experimental Investigation of Heat Transfer Enhancement by Using Different Number of Fins in Circular Tube

Abstract-The present work investigates the enhancement of heat transfer by using different number of circular fins (8, 10, 12, 16, and 20) in double tube counter flow heat exchanger experimentally. The fins are made of copper with dimensions 66 mm OD, 22 mm ID and 1 mm thickness. Each fin has three of 14 mm diameter perforations located at 120o from each to another. The fins are fixed on a straight smooth copper tube of 1 m length, 19.9 mm ID and 22.2 mm OD. The tube is inserted inside the insulated PVC tube of 100 mm ID. The cold water is pumped around the finned copper tube, inside the PVC, at mass flow rates range (0.01019 - 0.0219) kg/s. The Reynold's number of hot water ranges (640 - 1921). The experiment results are obtained using six double tube heat exchanger (1 smooth tube and the other 5 are finned one). The results, illustrated that the heat transfer coefficient proportionally with the number of fin. The results also showed that the enhancement ratio of heat transfer for finned tube is higher than for smooth tube with (9.2, 10.2, 11.1, 12.1 13.1) times for number of fins (8, 10, 12, 16 and 20) respectively.

Heat transfer enhancement and pressure drop of Fe3O4 -water nanofluid in a double tube counter flow heat exchanger with internal longitudinal fins

Use of internal fins in tubes of heat exchangers is a good practice for heat transfer enhancement. This paper reports an experimental study of forced convective heat transfer in a double tube counter flow heat exchanger with multiple internal longitudinal fins using Fe3O4 –water nanofluid. The convective heat transfer enhancement and pressure drop are investigated for the nanofluid flowing in a horizontal circular tube with internal longitudinal fins under turbulent conditions (5300 < Re < 49,200) and the volumetric concentration of Fe3O4 nanoparticles are in the range of 0 < φ < 0.4%. Results indicates that the heat transfer rate is 80–90% more in finned tube heat exchanger compared to the plain tube heat exchanger for the higher volumetric concentration of nanofluid. Nusselt number ratio of Fe3O4- water nanofluid with base fluid (water) increases with the Reynolds number. Friction factor decreases with the increase in Reynolds number and pressure drop is more in finned tube heat exchanger compared to the plain tube heat exchanger due to the effect of fin geometry which offers resistance to the flow. Wilson plot method is used to develop the Nusselt number correlation for the flow of Fe3O4- water nanofluid through the finned tube heat exchanger.

Estimation of Heat Transfer Coefficient and Thermal Performance Factor of TiO2-water Nanofluid Using Different Thermal Conductivity Models

Background: Enhancement of heat transfer rate is one of the most important aims in industrial applications. The conventional fluids including oil, water and ethylene glycol have poor thermal properties compared to those of most solids. With this information, it leads to the idea that, if we disperse very small particles and let them suspend stably in base fluids, thermal conductivities of that base fluids should be higher. In previous study of the authors, the effects of different thermal conductivity models on heat transfer and pressure drop of nanofluids were not carried out. In view of that consequence, this article is aimed at reporting the effect of different thermal conductivity models on the prediction of convective heat transfer coefficient and thermal performance factor of nanofluids experimentally. Method: An experimental study was performed for TiO2 -water nanofluid with a volume fraction between 0.002 and 0.02 and Reynolds number (Re) from 8,000 to 51,000. The experimental apparatus is a horizontal double tube counter-flow heat exchanger. Results: It shows that by growing the Re or nanoparticle volume fraction value, the Nusselt number enhances for all models studied. All equations used to calculate the thermal conductivity of nanofluid show same trends regarding the Nusselt number when Re or nanoparticle volume concentration changes. Some models could show more variation or low changes in the Nusselt number when the Re or nanoparticle volume concentration changes, however. Meanwhile, all nanofluids have a higher Nusselt number compared to distilled water. Conclusion: The nanofluid Nusselt number significantly enhances with growing Re and volume concentration for all thermal conductivity models studied in this work. By applying the nanofluid at a 0.02 nanoparticle volume fraction and Re equal to 47,000, the maximum thermal performance factor of 1.86 is found, based on Yu and Choi's and Jang and Choi's models. At low Re, all models show approximately same Nusselt numbers for all nanoparticle volume concentration. For moderate and high Re, the difference between the Nusselt numbers calculated by different models enhances. The thermal performance factor is higher than the unity for all Re and all volume concentration in this study, based on every thermal conductivity model. Keywords: TiO2-water nanofluid, thermal conductivity model, Nusselt number, thermal performance factor, turbulent flow, counter-flow heat exchanger.

Optimization of the tube in tube counter-flow heat exchanger in a 4.5 K hybrid J-T cryocooler to be used in space

Hybrid J-T cryocooler is commonly employed in space detective missions requiring liquid helium temperature. In fact, nearly all the space applications of mechanical cryocoolers working at 4.5 K, having been launched or under development are hybrid J-T cryocoolers. For instance, mechanical cryocoolers used in Planck, JWST, SMILES, SPICA and so on, are all J-T cryocoolers precooled by adsorption cryocooler, Stirling cooler or pulse tube cooler. But there is hard any research on space hybrid 4.5 K J-T cryocooler in China. Key Laboratory of Space Energy Conversion Technologies in Technical Institute of Physics and Chemistry has developed a 4.5 K J-T cooler precooled by three stages of pulse tube cryocooler. Base on this cryocooler, design optimization is carried out on the tube-in-tube counter flow heat exchanger to improve its performance. Counter flow heat exchanger is one of the key components of the 4.5 K hybrid J-T cryocooler. Spiral tube-in-tube heat exchanger is widely used in 4 K class hybrid J-T cryocooler because of its advantages of light weight and small size. The impact of tube-in-tube heat exchanger on J-T cycle is analyzed. And J-T cycle is able to provide more cooling capacity and needs less precooling power as the efficiency of the counter flow heat exchanger increases. Then, for the purpose of improving heat transfer efficiency of the counter flow heat exchanger, design optimization is carried out on the basis of theoretical analysis. The main heat transfer resistance of the counter flow heat exchanger is the convection heat transfer between return gas and the outer wall of inner tube. Thus, smaller tube is used to decrease the main heat transfer resistance. Besides, the centrifugal force of the moving helium flow in the spiral pipe brings about secondary flow. The development of secondary flow results in enhancement of heat transfer of the counter-flow heat exchanger. So heat transfer coefficient of the heat exchanger increases with decreasing diameters of the tubes and the spiral diameter. On the other hand, when the efficiency of the counter flow heat exchanger rises, the high pressure flow will be precooled much more fully, which means less precooling power from the precooling cooler will be consumed. As a result, the power consumption of the whole hybrid J-T cooler will decrease and its efficiency will be improved. Then, experimental research is conducted and the experimental results agree well with theoretical analysis. The temperature before throttling decreases as the efficiency of the counter flow heat exchanger increases. At the same time, the cooling capacity increases while the precooling power decreases. However, the cooling capacity and precooling power are smaller than theoretical analysis which attributes to the mass flow rate of calculation is much larger than measured one. Consequently, the benefit of improving heat transfer efficiency is verified. As the efficiency of the counter-flow heat exchanger increases, the cooling capacity of the J-T cooler is improved while the precooling power is cut down. Eventually, the cooling capacity of the hybrid J-T refrigerator at 4.7 K is improved from 15 to 32 mW.

Experimental study of Cu–water nanofluid heat transfer and pressure drop in a horizontal double-tube heat exchanger

This article reports an experimental study on the performance of horizontal double tube counter-flow heat exchanger. Due to the modicum in the heat transfer surface area, the overall heat transfer coefficient is enhanced. Cu-nanoparticles are added to the cold water in the annulus of the heat exchanger, however, the inner tube that contains the hot water is rotated. The inner tube is made of copper with 25.4mm outer diameter with a thickness of 2mm, while the outer tube, which is made of transparent Acrylic Plexiglass, has an outer diameter of 76.2mm and 5mm thickness. Cu–water nanofluid is prepared at volume fractions of 1–3% and the inner tube is rotated with speed from 0 to 500rpm. Results demonstrated a remarkable enhancement in the rate of heat transfer due to the nanoparticles addition as well as the inner tube rotation. Consequently, the effectiveness and the transfer number units (NTU) of the heat exchanger are augmented. Optimization between heat transfer augmentation and the pressure drop penalty is carried out. Finally, the use of the nanofluid has a little penalty in pressure drop in compared with the inner tube rotation.

Convective heat transfer characteristics of water–ethylene glycol mixture with silver nanoparticles

We report the convective heat transfer characteristics of water–ethylene glycol mixture fluids seeded with silver nanofluids under laminar, transitional and turbulent regime in this work. The volume concentrations of silver nanoparticles viz. 0.05%, 0.1%, 0.15%, 0.3% and 0.45% are considered. Thermophysical properties measurements such as thermal conductivity, viscosity, density and specific heat capacity were carried out using conventional techniques. Convection measurements were carried out in a tube in tube counter flow heat exchanger using nanofluids as the hot fluid. The effect of nanofluid mass flow rate ranging from 5g/s to 45g/s and inlet temperature of nanofluid at 35°C and 45°C on the convective heat transfer coefficient were investigated. The convective heat transfer coefficient was considerably increased with increasing Reynolds number, particle concentration and inlet temperature. The maximum enhancement of convective heat transfer coefficient of nanofluid is observed to be ∼42% at 0.45vol% compared with pure basefluid. The pressure drop of nanofluid increases marginally for a nanofluid volume concentration up to 0.15vol%. When compared with the base fluid, the difference of pressure drop is insignificant so that the use of nanofluid has limited penalty on the pressure drop up to 0.15vol% loading of silver nanoparticles. However, beyond 0.15vol% the pressure drop increases significantly which limits the use of these nanofluids at higher concentration for engineering applications.

Enhanced coefficient of performance by effective suction line cooling- an experimental report

The present paper is concerned with theoretical and experimental study and development of effective suction gas heat exchanger for hermetically sealed compressor. A single tube counter flow heat exchanger had been used, where water itself had been taken as a coolant. Energy consumption parameters as well as COP values have been obtained analytically for both the cases. Energy consumption parameter is 12% less as an average for a heat exchanger attached system compared to the system with out heat exchanger in a time span of 90 minutes. COP values obtained with heat exchanger are firmly better than that of the values with out Heat exchanger. COP values observed to be 7% higher for a heat exchanger coupled system compared to the system with out heat exchanger in the same time span of 90 minutes. In the present scenario where systems optimization is a necessity the present work would be useful in developing a energy efficient system with few modifications. This work would be useful to tackle the heat transfer related issues present in many gas compressors used in pumping and process industries.

Experimental investigation of diameter effect on heat transfer performance and pressure drop of TiO2–water nanofluid

In this paper, an experimental study performed to investigate the convection heat transfer characteristics in fully developed turbulent flow of TiO2–water nanofluid. The effect of mean diameter of nanoparticles on the convective heat transfer and pressure drop studied at nanoparticle volume concentration from 0.01 to 0.02 by volume. The experimental apparatus is a horizontal double tube counter-flow heat exchanger. The nanoparticles of TiO2 with diameters of 10, 20, 30 and 50nm dispersed in distilled water as base fluid. The results indicated higher Nusselt number for all nanofluids compared to the base fluid. It is seen that the Nusselt number does not increase by decreasing the diameter of nanoparticles generally. In this study both Nusselt number and pressure drop were considered in definition of thermal performance factor. The results show that nanofluid with 20nm particle size diameter has the highest thermal performance factor in the range of Reynolds number and volume concentrations were studied.

Experimental study on the effect of TiO2–water nanofluid on heat transfer and pressure drop

An experimental study performed to investigate the effect of nanoparticle volume fraction on the convection heat transfer characteristics and pressure drop of TiO2 (30nm)–water nanofluids with nanoparticle volume fraction between 0.002 and 0.02, and Reynolds number between 8000 and 51,000. The experimental apparatus is a horizontal double tube counter-flow heat exchanger. It is observed that by increasing the Reynolds number or nanoparticle volume fraction, the Nusselt number increases. Meanwhile all nanofluids have a higher Nusselt number compared to distilled water. By use the nanofluid at high Reynolds number (say greater than 30,000) more power compared to low Reynolds number needed to compensate the pressure drop of nanofluid, while increments in the Nusselt number for all Reynolds numbers are approximately equal. Therefore using nanofluids at high Reynolds numbers compared with low Reynolds numbers, have lower benefits.

An experimental investigation of thermo-physical properties and heat transfer performance of Al2O3-Aviation Turbine Fuel nanofluids

Aviation Turbine Fuel (ATF)-Al2O3 nanofluids are investigated for better heat transfer performance in a potential application of regeneratively cooled semi-cryogenic rocket engine thrust chambers. The volume concentration of Al2O3 nanoparticles is varied between 0 and 1%. To ensure a realistic evaluation, all properties of the nanofluids are experimentally measured rather than resorting to available formulae or empirical correlations. Among the thermo-physical properties, thermal conductivity and specific heat are measured separately using experimental set-ups fabricated in-house whereas the viscosity is determined using a commercial viscometer. The heat transfer coefficient is determined using a horizontal double tube counter-flow heat exchanger under turbulent flow conditions. At 1% particle volume concentration, the enhancement in the thermal conductivity is 40%, whereas the viscosity increases by 38%. The measured specific heats of the nanofluids do not exhibit appreciable difference within the range of the particle volume concentrations investigated. The heat transfer coefficient increases by 30% at 1% particle volume concentration and correspondingly leads to an enhancement of 10% in the Nusselt number. For the same value of pressure drop, the heat transfer performances of nanofluids are compared with those of ATF. The experimental results show that the maximum enhancement in the heat transfer coefficient observed for the same pressure drop is 28% and even the least enhancement obtained is 2%.

An experimental study on the heat transfer performance and pressure drop of TiO 2-water nanofluids flowing under a turbulent flow regime

Nanofluid is a new class of heat transfer fluids engineered by dispersing metallic or non-metallic nanoparticles with a typical size of less than 100 nm in the conventional heat transfer fluids. Their use remarkably augments the heat transfer potential of the base liquids. This article presents the heat transfer coefficient and friction factor of the TiO 2-water nanofluids flowing in a horizontal double tube counter-flow heat exchanger under turbulent flow conditions, experimentally. TiO 2 nanoparticles with diameters of 21 nm dispersed in water with volume concentrations of 0.2–2 vol.% are used as the test fluid. The results show that the heat transfer coefficient of nanofluid is higher than that of the base liquid and increased with increasing the Reynolds number and particle concentrations. The heat transfer coefficient of nanofluids was approximately 26% greater than that of pure vol.%, and the results also show that the heat transfer coefficient of the nanofluids at a volume concentration of 2.0 vol.% was approximately 14% lower than that of base fluids for given conditions. For the pressure drop, the results show that the pressure drop of nanofluids was slightly higher than the base fluid and increases with increasing the volume concentrations. Finally, the new correlations were proposed for predicting the Nusselt number and friction factor of the nanofluids, especially.