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Fuel cells are gaining popularity because of their efficient energy production without causing environmental pollution. Recently DRDO, has developed a fuel cell-based fuel cell-based Air Independent Propulsion (AIP) system. In this system, the hydrogen is produced onboard while oxygen is carried in liquified form (LOX) from the land in specially designed insulated storage vessels called dewars. Such vessels are needed because LOX has low boiling point (NBP ~ 90K) and heat of vaporization (~213 kJ/kg) due to which it boils off easily even when there is small amount of heat inleak from the ambient. A typical dewar consists of two vessels separated by insulation. Support members are used to hold the two vessels together. Heat inleak through the supports and the insulation of the dewar causes the boiling of LOX. The vessels are subjected to dynamic loads during the voyage as well as due to the filling and consumption of LOX. Therefore, the support system should be designed so that it can withstand the dynamic loads experienced by the dewar. While the support system should have enough mechanical strength to withstand the loads it is subjected to, it should also restrict the heat inleak from the ambient to minimize the LOX boil-off. To meet this requirement, we need to optimize the support system design. Design optimization of support systems is especially critical in submarines to reduce the snorkeling frequency. Even though the dewars are available commercially for various applications, their design methodologies are not available in the open literature. Cylindrical rods are generally used as support members. In earlier studies, the authors have shown that helical coils give better thermal performance than tension rods as dewar supports. These two support systems involve different design criteria. It is important to evolve an optimal design of the support system to maximize the mechanical strength of the support while minimizing the heat inleak through the support. In this paper we are presenting a design methodology for optimizing a helical support. We have proposed a modified optimization technique derived from the classical genetic algorithm (GA) for this purpose. The modification has been done by ensuring design feasibility of the coil at each step of the algorithm. The proposed optimization technique has been tested on a LOX dewar and an optimal design of the helical coil support has been obtained.

In the present study, an experimental study and a numerical method are used to simulate the effect of utilizing finned helical coil heat exchanger horizontally oriented with and without internal hollow core inside the shell and monitoring the heat transfer intensification behavior and performance enhancement, by using ANSYS FLUENT 2019R3 package. The working fluid in the inlet side of the coil will be superheated vapor refrigerant (R410a) after the compression stage of the air conditioner (1TR) split type, the working fluid in the shell side is water with various flow rates (1,2 and 3) LPM. Found that when using a heat exchanger with internal hollow core reduces the time needed to reach the steady-state outlet temperature and directly proportional to the size of the core by 20% and slightly increasing the water outlet temperature by 5%.

Embolization of the middle meningeal artery (MMA) is a safe and effective adjunct in the treatment of chronic subdural hematoma. While prior authors describe the use of coils to assist embolization by preventing reflux through eloquent collaterals, we de- scribe the use of coils to further open the MMA, allowing the administration of greater amounts of embolisate for a more robust embolization. The objective of this study was to demonstrate that helical coils can safely open the MMA following the administration of polyvinyl alcohol (PVA) particles. This allows for more embolisate to be administered into the MMA for more effective treatment. A retrospective review was conducted at our institution including intraoperative images and postoperative clinical and radiographic follow up. Failure rates using MMA embolization with PVA and helical coil augmentation were compared to failure rates in the literature of MMA embolization with PVA or ethylene vinyl-alcohol copolymer alone. A total of 8 cases were reviewed in which this technique was implemented. There were no immediate complications after treatment. All patients that underwent helical coil embolization following the administration of PVA had increased amount of embolisate delivered into the MMA. All patients at follow up had resolution of the subdural hematoma on outpatient imaging. Helical coil embolization allows for more embolisate administration into the MMA and provides a technical advantage for patients that fail traditional techniques of embolization. Case series are taking place to further test this hypothesis and identify the ideal patient population that may gain maximal yield from this novel technique.

Hydrodynamic and heat transfer characteristics of long-term stable nanofluids are very crucial for their industrial applications. Also utilization of coils is beneficial for industries as it provides a high rate of heat transfer and is compact in size too. So, the main focus of this study is to investigate the hydrodynamic and heat transfer characteristics of long-term stable f-CNT nanofluids when flowing inside a coil-based heat exchanger. f-CNT nanofluids were prepared by utilizing modified two-step method. To analyze the effect of different parameters on hydrodynamic and convective heat transfer characteristics, f-CNT concentration, $$ {\varvec{D}}_{{\mathbf{c}}}$$ , and Re were varied from 0 to 0.048 vol%, 95 to 175 mm, and 2300 to 9500, respectively. According to results, f-CNT concentration, $$ {\varvec{D}}_{{\mathbf{c}}}$$ , and Re substantially influenced the hydrodynamic and heat transfer characteristics of f-CNT nanofluids. It was found that improvement in h (152%) was much higher than the enhancement in friction factor (49%) when f-CNT nanofluid at 0.048 vol% was flowing through the coil of 95 mm diameter. Based on the heat transfer and hydrodynamic data, performance index was evaluated. The maximum performance index was calculated ⁓ 2.5, suggesting that the utilization of helical coils and f-CNT nanofluids is an excellent choice in industrial applications. Based on the experimental data, empirical correlations have been proposed to calculate the friction factor and Nusselt number for f-CNT nanofluids when flowing inside coils of different diameters and at different f-CNT concentrations. The proposed correlations explain the present experimental data within ± 15% and ± 20%, for friction factor and Nu, respectively.

A Helical coil Heat exchanger is a type of equipment built for reducing the space of heat exchanger without reducing its length of the tube. The heat carrier enrichment ways for swirl coil heat exchanger are widely applied in Test Cooling, Experimental Pre-moderate, complete moderators, Condensers, Ultracool Vaporizers, Compressor, Other Moderators and Wide Uses. The heat carrier enrichment is splits into Active way and Passive way. Enriching the heat carrier by the utilization of vertically coiled swirl tubes have been considered and experimented by several researchers to increase its efficiency by several ways. Here we are investigating the enrichment of heat carrier, passive way by using the different fluids to the swirl coil heat exchanger.

Rotary seed sorters used for wheat processing show some functional advantages in eliminating persistent contaminants, especially due to the more aggressive treatment applied to the processed material. The objective of this paper was to design a new constructive subassembly that would increase the performance of rotary sorters used for extracting various contaminants from seeds. By testing a pilot stand that reproduces the operation of a professional equipment and developing mathematical models that fits the main operating parameters, it was possible to identify the new characteristics needed to improve cylindrical sieves and to optimize the functioning of this equipment.

Rates of mass and heat transfer (by analogy) at the surface of a helical coil imbedded in a fixed bed of inert cylindrical packing were measured under upward two-phase (gas-liquid) flow by the elec...

Magnetic resonance coupling wireless power transmission (WPT) provides a safe and efficient power supply for small household appliances and implanted devices, but the tolerance of the transmission distance is poor. To improve the robustness of the transmission distance of the magnetic resonance WPT system, a method of using a reconfigurable helical coil array is proposed. Compared with the traditional four-coil structure of the same volume, different source and load coils are selected under distinct distance conditions. The coupling coefficient between the coils is changed to increase the stability of transmission efficiency and distance. To avoid the mechanical movement, all source and load coils have been adjusted at fixed position. Moreover, a control method is introduced to achieve coil switching. The experimental results show that the transmission distance of the proposed system is increased to 1.75 times of the coil diameter, while the efficiency remains above 70%.

Air conditioners (AC) and water heaters have become common needs in households and the hotel industry. This shows that the need for electric power is increasing. To reduce electricity consumption which is high enough. Engineering technology needs to be done for air conditioning as well as water heating. This engineering is called ACWH (Air Conditioner Water Heater). The way the ACWH system works is to utilize the wasted heat from the AC system to heat water with the addition of a fin heat exchanger, where the heat exchanger is designed to utilize the energy already in the system. This study used experimental research methods by testing at temperatures of 16, 18 ?, and 20 ? AC. The test results showed that the finned shell helical coil type heat exchanger was able to produce a water temperature of 55 ? in the test with an AC temperature of 18 ?.

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, air-conditioning 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.

The heat transfer, friction factor, pressure difference, Nusselt number of a helical coil tube using variable pressure and velocity during inlet for various values of Dean number [ratio of coil diameter (D) to tube diameter (d)] has been studied using commercially available computational tool. A validation is performed using the computational tool through the experimental data and it was observed that the results are in good agreement. The helical coil of 0.3 m diameter with four (4) turns of inner diameter 0.01 m with length 3.77 has been modelled, meshed and analyzed for both laminar and turbulent flows of constant wall temperature and heat flux. A grid independence test is also performed. The results show that increase in Dean number increases the heat transfer of the helical tube. The increases in pressure have less effect on heat transfer during laminar flow while adverse effect can be observed during turbulent flow.

In the present work, heat transfer and fluid flow characteristics for both Newtonian and non-Newtonian fluids in tube-in-tube helical coil (TTHC) heat exchangers have been investigated numerically....

The studies of nested helical coil heat exchangers for an absorption heat transformer are very limited, although this arrangement has a greater heat transfer area in a smaller volume. The heat exch...

To enable the design of a light water small modular reactor, the boiling flow inside a helical coil steam generator has been simulated with the two-fluid model in Nek-2P. Nek-2P is the multiphase b...

In the present study, thermal analysis of two heat exchangers, namely a shell and wire coil-inserted helical coil tube heat exchanger and a shell and without wire coil-inserted helical coil tube he...

With the development of the nuclear energy industry, small modular reactors (SMRs) have become an important option in China’s energy development due to their advantages in terms of safety and economics. The helical-coil steam generator is an important part of SMR, and the structure parameters need to be optimized urgently to reduce costs and improve safety. In this paper, various thermohydraulic parameters were used as indicators for the design quality of the helical-coil steam generator, such as the volume of the equipment, velocity of the flow, maximum temperature of the tubes, and natural circulation capability. The optimization of these target parameters has important theoretical and practical values. The genetic algorithm method is widely used to processes data efficiently, and it is able to reach a optimum design rapidly, which makes it a good choice for the optimization of parameters. The results show that this method could efficiently reduce the volume of the helical coil steam generator.

Helical coil steam generators (HCSGs) are tube and shell heat exchangers under investigation due to their future in nuclear power applications. A model of an HCSG with a transverse pitch ra...

espanolLos intercambiadores de calor de serpentin son empleados en varias aplicaciones industriales debido a su estructura compacta y los elevados coeficientes de transferencia de calor que usualmente se obtienen. En el presente trabajo se realizo el diseno de un intercambiador de calor de serpentin para llevar a cabo el enfriamiento de una corriente de acetona liquida. El equipo tendra un coeficiente global de transferencia de calor de 23,88 kcal/h.m2.oC, un area de transferencia de calor de 6,60 m2, un numero real de vueltas de serpentin igual a 53 y una altura de 2,58 m. Tanto la corriente de acetona como la de agua no sobrepasan la caida de presion maxima establecida por el proceso. Tambien se determino la influencia que presenta el incremento de tanto el caudal de alimentacion como la temperatura de entrada de la acetona sobre cuatro parametros de diseno del intercambiador de calor de serpentin: coeficiente global de transferencia de calor, area de transferencia de calor, numero real de vueltas del serpentin, y altura del equipo, obteniendose como resultado que el incremento de las dos variables iniciales aumenta los valores a obtener de estos cuatro parametros. Se utilizaron plantillas de calculo Excel tanto para la confeccion de los graficos como la solucion de la metodologia de calculo utilizada en este estudio. EnglishThe helical coil heat exchangers are employed in several applications due to their compact structure and the high heat transfer coefficients usually obtained. In the present work, the design of a helical coil heat exchanger is accomplished in order to carry out the cooling of a liquid acetone stream. The equipment will has an overall heat transfer coefficient of 23.88 kcal/h.m2.oC; a heat transfer area of 6.60 m2; an actual number of turns of coil equal to 53; and a height of 2.58 m. Both the acetone and the water stream do not exceed the maximum pressure drop established by the process. The influence of increasing both the acetone feed flowrate and inlet temperature on four design parameters of the helical coil heat exchanger: global heat transfer coefficient, heat transfer area, actual number of turns of the coil, and height of the equipment, was also determined, obtaining as a result that the increase of the two initial variables increases the values to be obtained of these four parameters. Excel spreadsheets were used to obtain the graphics and to solve the design methodology used in this study.

The paper focuses on hydrocarbon fuel cooling in launch vehicles, specifically considering experimental technique and results obtained during investigation of one of the primary heat exchanger parameters, that is, heat transfer coefficient of the heat exchanger surface. We present a model of efficient hydrocarbon fuel cooling by means of intensifying heat transfer on the external heat exchanger surface due to nitrogen sparging causing active motion in the liquid heat carrier. We obtained quantitative data regarding heat transfer on the external surface of a helical-coil heat exchanger located in a two-phase medium consisting of antifreeze and nitrogen, in the temperature range of 243--293 K. We derived a similarity equation for calculating heat transfer coefficient on the external heat exchanger surface, which is required to determine the heat exchanger surface area and to compute heat transfer from hydrocarbon fuel to the two-phase medium consisting of antifreeze and nitroge.

The paper presents the novel design of double glazing helical coil solar cavity receiver for solar thermal applications. Performance model has been developed for the experimental setup based on ene...

A model helical coil steam generator test section was designed and constructed to visualize the flow between two adjacent tube bundles—inner and outer bundle—that coil in opposite directions to one...

The present paper investigates the performance of helical coil solar cavity receiver based parabolic trough concentrator (PTC) for the conversion of energy received from the Sun into useful heat and finally electricity. The experimental set-up has been designed in such a way that it enhances heat transfer coefficient and reduces losses in the PTC. The PTC comprised of a blackened helical coil made up of two concentric borosilicate glass cylinder with vacuum in the annulus, which is kept at a focal line of PTC. The vacuum significantly reduces the losses which are evident from a relatively higher temperature of a 565 K obtained at the surface of the helical coil. Heat loss from helical coil solar cavity receiver has also been investigated and it was found that with the increase in vacuum pressure at annulus by 50%, the losses from the receiver has been increased by 26.67%. The heat loss from receiver has been observed to be proportional to the vacuum pressure within the annulus space.

Nanofluids have gained much attention due to excellent thermal properties. In this study, natural convection heat transfer behavior of three different types of non-Newtonian nanofluids in a shell and helical coil heat exchanger has been investigated experimentally under unsteady state conditions. Nanofluids were prepared by dispersion of Al2O3, Fe2O3 and CuO nanoparticles in an aqueous solution of carboxymethyl cellulose (CMC) (base fluid). Nanofluids of different concentrations (0.2, 0.4, 0.6, 0.8 and 1.0 wt%) were prepared by dispersing Al2O3, Fe2O3 and CuO nanoparticles in base fluid using probe sonication process. In the present study, the effect of shell-side nanofluid concentration, tube-side fluid (heating medium) temperature and flow rate parameters on heat transfer has been investigated.Results indicated that the addition of nanofluid has intensified heat transfer as indicated by the higher temperature of nanofluid when compared to base fluid. Out of the three materials used in the study, CuO nanofluid attained the highest temperature because of its higher thermal conductivity. Heat transfer rate decreased with time continuously for all the experimental conditions. Enhancement in heat transfer initially was higher compared to later times. At longer time the enhancement is less due to the lower buoyancy forces prevailing due to lower driving force. A maximum enhancement in heat transfer rate of 29.5 % has been obtained initially. The effect of nanofluid concentration on heat transfer rate with time exhibited different behavior compared to the effect of inlet temperature and flow rate.

In the present study, deep learning neural network model has been employed in many engineering problems including heat transfer prediction. The main consideration of this document is to predict the performance of the boiling heat transfer in helical coils under terrestrial gravity conditions and compare with actual experimental data. Total of 877 data sample has been used in the present neural model. Artificial new Neural Network (ANN) model developed in Python environment with Multi-layer Perceptron (MLP) using four parameters (helical coils dimensions, mass flow rate, heating power, inlet temperature) and one parameter (outlet temperature) has been used in the input layer and output layer in order. Levenberg-Marquardt (LM) algorithm using L2 Regularization to find out the optimal model. A typical feed-forward neural network model composed of three layers, with 30 numbers of neurons in each hidden layer, has been found as optimal based on statistical error analysis. The 4-30-30-1 neural model predicts the characteristics of the helical coil with the accuracy of 98.16 percent in the training stage and 96.68 percent in the testing stage. The result indicated that the proposed ANN model successfully predicts the heat transfer performance in helical coils and can be applied for others operation concerned with heat transfer prediction for future works

Highly sensitive application like spring needs some additional care in design. The impact of improvement is very high if its application is high or its significant effects on tangible and intangible benefits. This research identified a part in the automobile clutch system which replaces a massive amount of components from its instantaneous precursor, spring of coil type and clutch cover of lever-type. Such component is none other than helical coil spring of automobile light vehicle Suspension. Its cost is less due to its determined complication in shape and manufacturability. In most cases the mass of the component is the issue in automobile and in particularly such sensitive component of helical coil spring of automobile light vehicle Suspension. Hence here it is focused for material validation. The material validation is main aim of this piece of research. The materials like EN AW – 2011 -3.1655and Wrought Stainless Steel were considered for investigation. The SOLIDWORKS preferred for this study. The helical coil spring of automobile light vehicle Suspension is designed and modeled. The finite element analysis is employed to deploy the material behaviors in the computer aided investigation

The parabolic troughs are the most popular line focusing collectors. They are being used for process heating and medium temperature applications since long. In these collectors, the sunlight is concentrated at the receiver fixed at the focal line of the parabola. In general, the tubular types of receivers are used in the line focusing collectors. The working liquid is allowed to flow through the receiver tube. In the current study, the performance of a parabolic trough collector with the modified receivers is analyzed by experiments. Two types of receivers, viz. ‘U’-tube receiver and ‘helical coil receiver,’ enclosed in an evacuated glass tube are used. The system is installed at Nagpur [21.14° N, 79.08° E]; experiments have been performed in the month of February. The highest output temperature of 90 °C and the corresponding efficiency of 90.92% is obtained with helical coil receiver geometry. The details of receiver geometries and the experiments are discussed in this article.

The paper presents the results of numerical calculations on the magnetic field of a heliotron with a helical coil pitch L0, which comprises a helical coil section named as an L-section, where the helical coil pitch L differs from L0, i.e. L

Bayonet tube heat exchangers are a proposed solution for advanced nuclear reactor steam generators and heat removal systems, in particular in liquid metal cooled reactors. However, the performance of this heat exchangers is not very high due to the limited heat transfer surface; thus, many long bayonet heat exchangers are needed to remove significant power values. In the present paper, the use of a helical coiled downcomer inside the bayonet is proposed, instead of the traditional straight one, as a passive heat transfer enhancement method. The helical coiled downcomer acts on the annulus as a swirl flow device; for the evaluation of heat transfer and pressure drop it can be considered as a helical coiled wire or a helical coiled tape. The global thermal resistance between the heat source (external flow of primary fluid) and the heat sink (secondary fluid) is reduced, while the pressure drop is not excessively increased. The component behavior has been simulated using the thermal-hydraulic code RELAP5-3D, with lead and water respectively as primary and secondary coolants. A one-dimensional model has been adopted, modifying the heat transfer coefficient and the frictional pressure losses to properly simulate the helical coil effect with two different methods: the use of a heat transfer coefficient multiplication factor and the adoption of the swirl tube heat transfer mode. The component has been operated as a steam generator considering the parameters and the boundary conditions of ALFRED reactor proposed design. Two different downcomer tube dimensions have been considered (6–8 mm and 8–10 mm ID-OD) with five helical pitches (5, 7.5, 10, 15 and 20 cm), which have been selected taking into account the manufacturing constraints. The results show a significant improvement of the bayonet heat exchanger performance. The removed power increases more than 8% and the steam superheating increases around 23 K for the best configuration.

This paper presents a highly efficient power transfer system based on a co-design of a class-E power amplifier (PA) and a pair of inductively coupled Helical coils for through-metal-wall power transfer. Power is transferred wirelessly through a 3.1-mm thick aluminum barrier without any physical penetration and contact. Measurement results show that the class-E PA achieves a peak power gain of 25.2 dB and a maximum collector efficiency of 57.3%, all at 200 Hz. The proposed system obtains a maximum power transfer efficiency of 9% and it can deliver 5 W power to the receiver side through the aluminum barrier.

For evaluating the heat transfer correlations from literature in designing helical coil evaporators for low-temperature organic Rankine cycles (ORC), an inverse evaporator design methodology is use...

The vehicle suspension system connects a vehicle to its wheels and contributes to the vehicle's road handling and braking for better safety and driving pleasure, and offering a comfortable ride well isolated from road noise, bumps, vibrations etc. Many people have own vehicles but they don’t know the importance of shock absorber and how to maintain it. So, it becomes important that the shock absorbers are efficient, durable and cost efficient. Material used for the helical coil spring is of great importance as it is one of the main part of suspension system. Various research papers arebased on analysis done using different materials. Many papers were published regarding “Analysis and Design of Shock Absorbers”. This paper is a review of previous literatures that cover the topic of design and analysis of shock absorbers. Observations and recommendations are shared according to the research gaps in the literature.

In this article, the heat transfer performance of a syngas cooler with membrane helical-coil heat exchanger was numerically studied. A method of combining piecewise simulation and full-scale simula...

In the present study, thermal hydraulic investigation of a steam generator of an integral small modular reactor (SMR) has been performed. For this investigation, a helical coil steam generator of IRIS design is selected due to availability of its design parameters in literature. Steam generator model is developed in RELAP5/Mod 4.0. At first, steady state simulation has been performed for this model and results are found in good agreement with the IRIS design data. In order to evaluate the behavior of steam generator under accidental conditions, transient analysis has also been performed. Steam generator performance is assessed for two transients, namely, feed line break (FLB) and loss of flow accident (LOFA). Exponential losses of secondary side pressures (inlet and outlet) are considered for FLB, whereas an exponential loss of primary flow rate is considered for LOFA. The results indicate safe and reliable operation of IRIS steam generator for both transients.