Helically Coil Heat Exchanger

My special thanks go to my supervisor (Engr. Mrs Mary Onyia) for her relentless effort in supervising my project. She ensured the project was successful. Mr Malachy , for his assistance throughout the construction and fabrication process of the project and my other lecturers in the department of Mechanical Engineering, Caritas University Amorji-Nike Enugu. I would like to thank my lovely parent financial support and encouragement. Finally, to my project partners Webster and Atuchi for their seriousness and diligence in making sure the entire construction process was a huge success. Not forgetting my honourable lecturers who made sacrifices in tutoring me in mechanical engineering field.

Heat transfer enhancement due to the helically coiled heat exchanger is a burning topic in the field of research. But so far, there is no experimental or theoretical analysis of a helically coiled heat exchanger considering fluid-to-fluid heat transfer published, hence intending our work on this subject by using Methanol in water solution as a cold fluid. Methanol (also known as methyl alcohol, carbonyl, wood alcohol, wood naphtha or wood spirits) is a chemical compound with chemical formula CH3OH. It is the simplest alcohol and is a light, volatile, colourless, flammable, poisonous liquid with a distinctive odour that is somewhat milder and sweeter than ethanol (ethyl alcohol). At room temperature, it is a polar solvent and is used as antifreeze, solvent, and as a denaturant for ethyl alcohol. The Methanol, when prepared a solution with water, can be used as a coolant in the Heat Exchanger (Helically Coiled Heat Exchanger in our case) to take advantage of their improved heat transfer properties which would result in enhanced heat transfer in the helical coil heat exchanger. For this purpose, a solution was prepared with varying proportion of Methanol in water. We used four concentrations of 5%, 10%, 15% and 20% of methanol by volume in 5 litres of water. Water is Polar and Methanol as well. So, when we put methanol in water it gets dissolved and producing intermolecular forces i.e. hydrogen bonding. Various properties such as pH, Electrical Conductivity, Thermal Conductivity, boiling point etc. were tested.

The present work experimentally investigate the characteristics of convective heat transfer in horizontal shell and coil heat exchangers in addition to friction factor for fully developed flow through the helically coiled tube (HCT). The majority of previous studies were performed on HCTs with isothermal and isoflux boundary conditions or shell and coil heat exchangers with small ranges of HCT configurations and fluid operating conditions. Here, five heat exchangers of counter-flow configuration were constructed with different HCT-curvature ratios (δ) and tested at different mass flow rates and inlet temperatures of the two sides of the heat exchangers. Totally, 295 test runs were performed from which the HCT-side and shell-side heat transfer coefficients were calculated. Results showed that the average Nusselt numbers of the two sides of the heat exchangers and the overall heat transfer coefficients increased by increasing coil curvature ratio. The average increase in the average Nusselt number is of 160.3% to 80.6% for the HCT side and of 224.3% to 92.6% for the shell side when δ increases from 0.0392 to 0.1194 within the investigated ranges of different parameters. Also, for the same flow rate in both heat exchanger sides, the effect of coil pitch and number of turns with the same coil torsion and tube length is remarkable on shell average Nusselt number while it is insignificant on HCT-average Nusselt number. In addition, a significant increase of 33.2% to 7.7% is obtained in the HCT-Fanning friction factor (f_c) when δ increases from 0.0392 to 0.1194. Correlations for the average Nusselt numbers for both heat exchanger sides and the HCT Fanning friction factor as a function of the investigated parameters are obtained.

This study presents an experimental investigation of the characteristics of convective heat transfer in horizontal shell and coil heat exchangers in addition to the friction factor for fully developed flow through their helically coiled tube (HCT). Five heat exchangers of counter-flow configuration were constructed with different HCT-curvature ratios (δ) and tested at different mass flow rates and inlet temperatures of Al2O3/water nanofluid in the HCT. The tests were performed for Al2O3 with average size of 40 nm and particles volume concentration (φ) from 0 to 2% for 0.0392≤δ≤0.1194. Totally, 750 test runs were performed from which the HCT-average Nusselt number (Nut) and Fanning friction factor (fc) were calculated. Results illustrated that Nut and fc of nanofluids are higher than those of the pure water at same flow condition, and this increase goes up with the increase in φ. When φ increases from 0 to 2%, the average increase in Nut is of 59.4% to 81% at lower and higher HCT-Reynolds number, respectively, and the average increase in fc is of 25.7% and 27.4% at lower and higher HCT-Reynolds number, respectively, when φ increases from 0 to 2% for δ=0.1194. In addition, results showed that Nut and fc increase by increasing coil curvature ratio. When δ increases from 0.0392 to 0.1194 for φ=2%, the average increase in Nut is of 130.2% and 87.2% at lower and higher HCT-Reynolds number, respectively, and a significant increase of 18.2% to 7.5% is obtained in the HCT-Fanning friction factor at lower and higher HCT-Reynolds number, respectively. Correlations for Nut and fc as a function of the investigated parameters are obtained.

The present work introduces an experimental study of horizontal shell and coil heat exchangers. Characteristics of the convective heat transfer in this type of heat exchangers and the friction factor for fully developed flow through their helically coiled tube (HCT) were investigated. The majority of previous studies were performed on HCTs with isothermal and isoflux boundary conditions or shell and coil heat exchangers with small ranges of HCT configurations and fluid operating conditions. Here, five heat exchangers of counter-flow configuration were constructed with different HCT-torsions (λ) and tested at different mass flow rates and inlet temperatures of both sides of the heat exchangers. Totally, 295 test runs were performed from which the HCT-side and shell-side heat transfer coefficients were calculated. Results showed that the average Nusselt numbers of both sides of the heat exchangers and the overall heat transfer coefficient increase by decreasing coil torsion. At lower and higher HCT-side Reynolds number (Ret), the average increase in the HCT-side average Nusselt number (Nut) is of 108.7% and 58.6%, respectively, when λ decreases from 0.1348 to 0.0442. While, at lower and higher shell-side Reynolds number (Resh), the average increase in the shell-side average Nusselt number (Nush) is of 173.9% and 69.5%, respectively, when λ decreases from 0.1348 to 0.0442. In addition, a slight increase of 6.4% is obtained in the HCT-Fanning friction factor (fc) at lower Ret when λ decreases from 0.1348 to 0.0442, and this effect vanishes with increasing Ret. Furthermore, correlations for Nut, Nush and fc are obtained.

Heat Exchangers are one of the most important engineering systems with various applications like power plants, nuclear reactors, refrigeration and airconditioning , heat recovery systems; chemical processing and food industries. Basic advantage of helical Coil heat exchanger is its higher heat transfer with compact size, due to secondary flow generation in coil. One of the passive methods of heat transfer enhancement is used here, by changing the design of helical coil. Few investigators have introduced Critical Reynolds number to identify the transition from laminar to turbulent flow in helical coils which is given by Schmidts Co-relation. An attempt is made to change the curvature ratio continuously throughout the coil by using a conical shaped coil in order to decrease the critical Reynolds number. Numerical results of conical coil are compared with straight helical coil by using ANSYS fluent for mass flow rate through coil 0.07kg/s and 0.05 kg/s through shell. From Numerical analysis it is observed conical coil giving 8.71% more heat transfer than straight coil. The mass flow rate range through coil is taken 0.01 kg/s, 0.02 kg/s, 0.05 kg/s, 0.07 kg/s, 0.09 kg/s, 0.1 kg/s keeping mass flow rate through shell 0.05 kg/s constant also tube inlet and shell inlet temperatures maintained same 42ºC and 27ºC respectively and for same mass flow rate heat transfer rate calculated numerically.

Mathematical heat transfer equations for finned double pipe heat exchangers based on experimental work
carried out in the 1970s can be programmed in a spreadsheet for repetitive use. Thus avoiding CFD
analysis which can be time consuming and costly. However, it is important that such mathematical
equations be evaluated for their accuracy. This paper uses CFD methods in evaluating the accuracy of
mathematical equations. Several models were created with varying; geometry, flue gas entry temperature,
and flow rates. The analysis should provide designers and manufacturers a judgment on the expected level
of accuracy when using mathematical modelling methodology. This paper simultaneously identifies best
practices in carrying out such CFD analysis.
Methodology; CFD software was used to simulate different models. Results were tabulated and graphically
presented. The investigated mathematical equations were programmed in a spreadsheet, for data entry.
Results and analysis; data obtained from the two methods were compared and differences were recorded.
Discussions were included explaining the possible reasons for the deviations that surfaced between the two
methodologies.
Conclusions; this analysis has shown that although mathematical equations are effective and simple tools
in producing results, the results may not reflect the actual physical conditions. The analysis showed that the
exhaust gas temperature outlet of a double pipe heat exchanger is actually higher than what were
calculated using mathematical equations, and therefore, more heat energy is available for recapturing.
k-epsilon RNG turbulence model was found to be the most suitable method in analyzing heat transfer in a
finned double pipe heat exchanger.

La discusión sobre el papel de la extracción de recursos naturales no renovables en el desarrollo económico y social del país requiere, con urgencia, adelantar un debate amplio e informado que contemple las distintas aristas de una actividad con implicaciones de por sí complejas y con múltiples ramificaciones sobre prácticamente todas las esferas de la vida nacional.

Heat Exchangers are one of the most important engineering systems with various applications like power plants, nuclear reactors, refrigeration and air conditioning, heat recovery systems, chemical processing and food industries. Basic advantage of helical Coil heat exchanger is its higher heat transfer with compact size, due to secondary flow generation in coil. One of the passive methods of heat transfer enhancement is used here, by changing the design of helical coil. Few investigators have introduced Critical Reynolds number to identify the transition from laminar to turbulent flow in helical coils which is given by Schmidts Co-relation. An attempt is made to change the curvature ratio continuously throughout the coil by using a conical shaped coil in order to decrease the critical Reynolds number. Then fabrication of both straight and conical coil heat exchangers is done for experimentation work. The mass flow rate range through coil is taken 0.01 kg/s,0.02 kg/s, 0.05 kg/s,0.07 kg/s,0.09 kg/s, 0.1 kg/s keeping mass flow rate through shell 0.05 kg/s constant also tube inlet and shell inlet temperatures maintained same 42ºC and 27 ºC respectively for all mass flow rate. This experimentation is done in parallel as well as in counter flow arrangement. Experimental results of conical coil are compared with straight helical coil. As mass flow rate through coil increases there is increment in shell outlet temperature by enhancement of heat transfer by 2.78%, average heat transfer and LMTD by 12%, heat transfer coefficient by 4%, overall heat transfer coefficient by 11% and decrement in friction factor and pressure drop by 40% in conical coil heat exchanger counter arrangement as compare to straight coil heat exchanger.

A review on reutilization of heat waste from a diesel machine is absolutely important. This is because the exhaust gas potential of a Diesel machine keeps increasing and not much has been utilized by the industry. One of the techniques of reutilizing the heat waste in industry is by using a heat exchanger. The technique is also very useful for the environment because it can reduce air pollution caused by the exhaust gas of the diesel machine. The main purpose of the research is to find out the capability of shell and multi-tube helical coil HE as an air heater by utilizing the exhaust gas of the Diesel machine. The heat exchanger of shell and multi-tube helical coil  utilizes the exhaust thermal gas of the Diesel machine as the air heater already made. The apparatus has the following dimension: the shell length of 1.05 m, diameter 0.1524 m, tube length of 3.25 m with 20 coils, tube diameter of 0.011 m, coil diameter of 0.0508 m with 4 helical coils. The type of Diesel machine to use in the testing is 4FB1 Isuzu Diesel engine. The machine has the maximum machine power and rotation of 54 kW and 3,600 rpm. The performance testing of heat exchanger has been conducted in some variations of Diesel machine rotations of 1,500 rpm, 1,750 rpm, 2,000 rpm, 2,250 rpm and 2,500 rpm. The testing result shows a maximum effectiveness to happen at the machine rotation of 1,500 rpm. The maximum effectiveness to get is 67.8% and then it goes down drastically in accordance with the increase of air mass flow rate. The hot air temperature created is from 47.1°C to 52.3°C so that it can be used for the purpose of drying up the unhulled rice

International Journal of Scientific Research in Science, Engineering and Technology (www.ijsrset.com) © 2020 IJSRSET | Volume 7 | Issue 2 | Print ABSTRACT Aim of this review work is to examine the relative advantage of using an inclined helical coil tube heat exchanger for high-pressure syngas under various industries application. It observed that the heat transfer in the helical coil tube is higher as compared to the straight tube due to their shape. Inclined helical coil tube heat exchanger offers advantageous over straight tubes due to their compactness and increased heat transfer coefficient. The increased heat transfer coefficients are a consequence of the curvature of the coil, which induces centrifugal forces to act on the moving syngas. Due to the curvature effect, the fluid streams in the outer side of the pipe moves faster than the syngas streams on the inner side of the tube. Heat transfer augmentation techniques refer to various methods used to increase the heat transfer rate without changing much the overall performance of the system. The arrangements are useful in a variety of applications where more heat transfer rates desired. Some of the claims involved in heat exchanger used in Thermal Power plants, process industries, airconditioning equipment, heating and cooling in evaporators, radiators for space vehicles, automobiles, refrigerators. These techniques broadly of three types viz. passive, active, compound heat transfer augmentation techniques. The present paper reviews the experimental investigation of free and forced convection heat transfer from different helical coiled tubes.

This work proposes the low power implementation of Viterbi Decoder. Majority of viterbi decoder designs in the past use simple Register Exchange or Traceback method to achieve very high speed and low power decoding respectively, but it suffers from both complex routing and high switching activity. Here simplification is made in survivor memory unit by storing only m-1 bits to identify previous state in the survivor path, and by assigning m-1 registers to decision vectors. This approach eliminates unnecessary shift operations. Also for storing the decoded data only half memory is required than register exchange method. In this paper Hybrid approach that combines both Traceback and Register Exchange schemes has been applied to the viterbi decoder design. By using distance properties of encoder we further modified to minimum transition hybrid register exchange method. It leads to lower dynamic power consumption because of lower switching activity. Dynamic power estimation obtained through gate level simulation indicates that the proposed design reduces the power dissipation of a conventional viterbi decoder design by 30%.

A review on reutilization of heat waste from a diesel machine is absolutely important. This is because the exhaust gas potential of a Diesel machine keeps increasing and not much has been utilized by the industry. One of the techniques of reutilizing the heat waste in industry is by using a heat exchanger. The technique is also very useful for the environment because it can reduce air pollution caused by the exhaust gas of the diesel machine. The main purpose of the research is to find out the capability of shell and multi-tube helical coil HE as an air heater by utilizing the exhaust gas of the Diesel machine. The heat exchanger of shell and multi-tube helical coil  utilizes the exhaust thermal gas of the Diesel machine as the air heater already made. The apparatus has the following dimension: the shell length of 1.05 m, diameter 0.1524 m, tube length of 3.25 m with 20 coils, tube diameter of 0.011 m, coil diameter of 0.0508 m with 4 helical coils. The type of Diesel machine to use...

Three stage standalone solar thermal Multi Effect Desalination (MED) pilot plant for remote and arid rural regions of Sultanate of Oman using fixed focus type Scheffler concentrator producing 100 litres per day has been set up at author's institute. Preliminary tests carried out on this plant yielded lower outputs of 60-65 litres per day. Heat loss through high temperature brine discharged at 85 o C was observed as one of the reasons for lower yield. Literature reviewed and analysis shown that desalination outputs can be increased with increased feed water inlet temperature. To recover this heat and preheat the feed water supplied, brine heat recovery unit using counter flow type shell and coil heat exchanger has been proposed in this paper. Helically coiled heat exchanger has been selected for its compactness, higher heat transfer area per unit volume, higher inside heat transfer coefficient and lower fouling rates due to induced turbulence. The operating parameters of this heat exchanger will handle hot brine at 80-85 o C and 1 bar pressure. In the present work, heat load, number of turns, coil length and pressure drop calculations are done for estimating the theoretical values based on heat transfer & fluid mechanics principles using numerical correlations from the literature reviewed. The steady state analysis has shown that that coil pitch,inside tube diameter, mass flow rate through the coil and shell affects the heat transfer rates. Practical dimensional constraints have been taken into consideration while finalising the dimensions of the heat exchanger. Overall effectiveness of 84.6% has been calculated for the proposed heat exchanger.

Three stage standalone solar thermal Multi Effect Desalination (MED) pilot plant for remote and arid rural regions of Sultanate of Oman using fixed focus type Scheffler concentrator producing 100 litres per day has been set up at author's institute. Preliminary tests carried out on this plant yielded lower outputs of 60-65 litres per day. Heat loss through high temperature brine discharged at 85 o C was observed as one of the reasons for lower yield. Literature reviewed and analysis shown that desalination outputs can be increased with increased feed water inlet temperature. To recover this heat and preheat the feed water supplied, brine heat recovery unit using counter flow type shell and coil heat exchanger has been proposed in this paper. Helically coiled heat exchanger has been selected for its compactness, higher heat transfer area per unit volume, higher inside heat transfer coefficient and lower fouling rates due to induced turbulence. The operating parameters of this heat exchanger will handle hot brine at 80-85 o C and 1 bar pressure. In the present work, heat load, number of turns, coil length and pressure drop calculations are done for estimating the theoretical values based on heat transfer & fluid mechanics principles using numerical correlations from the literature reviewed. The steady state analysis has shown that that coil pitch,inside tube diameter, mass flow rate through the coil and shell affects the heat transfer rates. Practical dimensional constraints have been taken into consideration while finalising the dimensions of the heat exchanger. Overall effectiveness of 84.6% has been calculated for the proposed heat exchanger.

Water nanofluids were examined in a horizontal helical coil tube with constant temperature limitations for Dean values between 1000 and 10,000 to determine the rate of thermal radiation transmission and pressure drop characteristics. When conducting the tests, a variety of Al2O3 water nanofluid requirements were used, including varying mass flows, heat exchange rates for various nanoparticle volume concentrations, and changes in coil-side drop in pressure versus coil-side Dean number. Since nanoparticles have enhanced heat capacity, nanoparticles are developing as a transitional beginning of heat transfer fluids with significant potential in thermal management applications. Many applications require nanofluids to be used as heat transfer fluids; thus, scientists are concentrating their efforts on these fluids. The Reynolds values on the coil and shell were in the 1000 to 7000 range on either side of the wire. This paper discusses the impact of particle volume density on shell-side f...

En 12 anos, la extraccion anual de carbon paso de 3,5 millones a 8 millones de toneladas. Representa 1,5% del PIB, 3,7% del impuesto a la renta y 15 % de las regalias minero-energeticas, ocupando el segundo lugar en las exportaciones, despues del petroleo. Pero tiene pocos encadenamientos con otros sectores productivos. Entre 2001 y 2012 genero menos de 15 mil empleos, muy por debajo de las actividades agropecuarias (223 mil) y manufactureras (517 mil). Las condiciones sociales en donde se extrae son criticas: 58% de las familias no tienes necesidades basicas satisfechas y 75% de las mismas estan en un nivel de pobreza multidimensional. El carbon se explota en zonas de alto conflicto, alcanzando en un ano 360 muertes violentas y mas de 140 desplazados, por cada 100 mil habitantes. Al menos una de las mas grandes empresas que lo extrae ha sido sancionada por graves danos ambientales y declarada culpable por afectaciones, igualmente graves, a la salud humana. En fin, la poblacion sopo...

This research work investigates the flow field and the heat transfer characteristics of a Membrane Helical Coil Heat Exchanger for the cooling of syngas. Finite volume method based on FLUENT software practised and the RNG k-e turbulence model was adopted for modelling flow turbulent. The distribution of the resistance, the distribution of the heat source, and the porosity rate introduced to ANSYS R18.0 by coupling the user-defined function. The variation of local heat transfer,the pressure drop, and the temperature distribution studied under the effects of the syngas components and the operating pressure, and the impact of the arrangement of the membrane on the heat transfer investigated. The results show that higher operating temperature and pressure can improve the heat transfer, however, brings more significant pressure and temperature drop. The components of the syngas significantly affect the heat transfer and the pressure drop. The arrangement of the membrane influences the fluid flow.

In the present article, forced convection heat transfer and pressure drop in helically coiled pipes using TiO2/water nanofluid as working fluid were investigated experimentally and numerically. The aim is to investigate and provide additional insight about the effects of physical and geometrical properties on heat transfer augmentation and pressure drop in helically coiled tubes. The experiments were conducted in the range of Reynolds number from 3000 to 18,000 and in the nanoparticle concentrations of 0.1, 0.2, and 0.5% for five different curvature ratios. In numerical simulations the thermophysical properties of the working fluid were assumed to be a function of nanofluid temperature and concentration. For turbulent regime the standard k − ε model was used to simulate the turbulent flow characteristics. The numerical results were in good agreement with the experimental data. The results showed that utilization of nanofluid instead of distilled water leads to an enhancement in the Nusselt number up to 30%. Also, four formulas were introduced to obtain the average Nusselt number and friction factor in helically coiled tubes under constant wall temperature condition for both laminar and turbulent flow regimes.