Shell Tube Heat Exchanger Research Articles

EVALUATION AND ANALYSIS OF THE SUSTAINABLE WASTE-TO-ENERGY SYSTEM PERFORMANCE FOR THE POULTRY FARM

Poultry litter is one type of biomass and waste generated from the poultry farms. However, excess land application of poultry litter caused eutrophication problems of surface waters coming from the watershed and destroyed the aquatic ecology. Co-combustion of poultry litter and coal were widely studied in fluidized bed combustor as an alternative disposal method during last two decades. However, there are severe environmental problems (i.e., gaseous emissions) and public health impact associated with the poultry litter and coal co-combustion process. In this study, poultry litter and natural gas co-combustion was investigated in the lab-scale waste-to-energy system to provide a sustainable and cost-effective disposal route for poultry farms. This waste-to-energy system integrates the Stirling Engine (SE), Shell-Tube Heat Exchanger (STHE) and the lab-scale Swirling Fluidized Bed Combustor (SFBC) with other systems (e.g., cyclone, air supply system, fuel feeding system). Measures of heat transfer effect, electricity output and gas emissions levels were used to evaluate the lab-scale waste-to-energy system performance. Results indicated that lab-scale waste-to-energy system can produce electricity (close to 1 kW) and hot water (57.2°C) while reducing NOx and SO2 emissions during the poultry litter and natural gas co-combustion process. In addition, energy flow analysis indicated that SE and STHE system might use 14.7% and 21.0% of total energy input in fuels, respectively, to generate useful energy. In addition, a sustainable life cycle of poultry litter was built and suggested to process poultry wastes in the poultry farms.

Analysis of the influence of the tubes constrained structure of contra-flow vertical shell and tube heat exchanger on heat transfer ability with natural circulation

In order to verify the effect of the combined restraint form of straight strip and corrugated strip on the heat transfer capacity of shell-tube heat exchanger with natural circulation. The physical model and mathematical model of the local heat exchange section of the heat exchanger are established by using ICEM and Fluent to carry out numerical simulation. The calculation results of three-dimensional flow field and temperature field of the heat exchange section are solved and analysed to obtain the resistance characteristics of the tube bundle of shell-and-tube heat exchanger under the restriction of corrugated strip and straight strip with natural circulation and the influence at the temperature field.

Computational Fluid Dynamics Analysis of Flow Patterns, Pressure Drop, and Heat Transfer Coefficient in Staggered and Inline Shell-Tube Heat Exchangers

In this numerical study, the heat transfer performance of shell-and-tube heat exchangers (STHXs) has been compared for two different tube arrangements. STHX having 21 and 24 tubes arranged in the inline and staggered grid has been considered for heat transfer analysis. Shell-and-tube heat exchanger with staggered grid arrangement has been observed to provide lesser thermal stratification as compared to the inline arrangement. Further, the study of variation in the mass flow rate of shell-side fluid having constant tube-side flow rate has been conducted for staggered grid structure STHX. The mass flow rate for the shell side has been varied from 0.1 kg/s to 0.5 kg/s, respectively, keeping the tube-side mass flow rate as constant at 0.25 kg/s. The influence of bulk mass-influx transfer rate on heat transfer efficiency, effectiveness, and pressure drop of shell-tube heat exchangers has been analyzed. CFD results were compared with analytical solutions, and it shows a good agreement between them. It has been observed that pressure drop is minimum for the flow rate of 0.1 kg/s, and outlet temperatures at the shell side and tube side have been predicted to be 40.94°C and 63.63°C, respectively.

Analysis of printed circuit heat exchanger (PCHE) for Small modular molten salt reactor (MSR)

Energy is the backbone of defense and essential for the effectiveness of operations. The archipelago country like Indonesia has a specific characteristic when deploy the army separated over the country will have deep complexity in energy distribution and security. The mobile nuclear power plant is interesting to evaluate, and we interested in heat transfer process in the heat exchanger. The paper presents the potential of the application of a printed circuit heat exchanger (PCHE) on small modular molten salt reactors (MSR) for the military. The Heat exchanger is played a crucial role in the nuclear reactor design where the size compaction and efficiency improvement two issues that must be solved. The PCHE promise some advantages such as high effectiveness, high surface area per volume, light and compact. We evaluate and compare the performance of the heat exchanger of the MSRE ORNL 8 MWTh with PCHE’s design where MSRE a benchmarking. The result shows that low-pressure drops, low-pumping power and high effectiveness and compactness (low-dimension). We recommended that PCHE is applied on MSR than conventional HX like a Shell tube heat exchanger (STHE) of MSRE ORNL.

Optimization of Energy Consumption in the Process of Dehumidification of Natural Gas

In recent years, there has been a great tendency to optimize energy consumption in the oil and gas industry’s upstream and downstream equipment. One of the most energy-intensive processes in natural gas refineries is the condensate stabilization unit (gas condensate). The main bottlenecks of energy consumption in the old units are condensated stabilization (dehumidification with ethylene glycol), heater reboiler, and air coolers (air coolers). Therefore, much attention should be paid to these applications and electricity and steam consumption in this unit. In this study, a simulated model based on the Gachsaran gas refinery’s new layout has been developed. Optimization of this part of the existing process is preheating the inlet flow to the reboiler by adding a two-stage shell-tube heat exchanger. This reduces the amount of steam needed to evaporate the inlet stream to the end of the tower. On the other hand, by pre-cooling the inlet currents to the air conditioners, the amount of electricity consumed to reach the outlet flows’ the desired temperature would be reduced. The results show an attractive return on investment for the remediation plan, a reduction in energy demand, and an increase in the unit’s productivity.

Theoretical Analysis of a Lignite-Fired Power Plant with Pre-Drying System in Terms of Energy Efficiency and Economy

The coals with different initial moisture content to be used in the theoretical analysis were tested according to the related test standards and the results were used in the analysis. In the designed system, waste heat in the flue gas is used as the heat source. The fresh air is heated for drying in the shell-tube heat exchanger by means of flue gas. In fluidized bed dryers, the moisture of the coal was reduced by contacting the raw coal with the drying air. Due to the high initial moisture of the coals used in the theoretical analysis, the pre-drying degree could be at most 0.14 in order that the boiler feeding rate be the same as in the power plant feeding rate without pre-drying system. The system theoretically does not conform to the design parameters and the boiler feed rate is less than the flow rate of power plant without pre-drying system when the pre-drying degree is greater than 0.14. The pre-drying system had ten small capacity dryers working simultaneously to ensure the continuity of the boiler feed. In the study, the theoretical analysis was performed, and thermal performance of the power plant were formulized and graphically presented according to pre-drying degree. Thanks to the pre-drying system, owing to the decrease in the moisture content of the coal, a reduction in the flue gas flow rate and the amount of energy required to evaporate the moisture are realized. As a result, there was a decrease in the boiler losses and an increase in the efficiency of the boiler. The increase in boiler efficiency was 10.74% when coal 1 had been used and it was 7.92% when coal 2 had been used. Since the coals are dried in the same drying system under the same conditions, the moisture of coal 1 decreases more, thus the losses of the boiler decrease more. Due to the increase in the lower heating value and in the boiler efficiency, the efficiency of the power plant with pre-drying could increase by 3.04-4.34%. The coal pre-dried power plant had far more economic performance than a power plant without pre-drying system, since more electricity would be obtained thanks to the increase in efficiency of the plant. The redemption period of the system was determined as 2 years with coal 1 and it was determined as 3 years with coal 2. After the payback periods, the system makes a net profit and brings in an average of 55 million TL extra income per year. In addition, it was observed that when the degree of pre-drying was decreased, economic efficiency of the system also decreased. It is aimed that the study will provide principles of energy efficiency improvement in coal fired power plants with pre-drying system and will guide people who wants to do similar studies.

Flow field simulation and stress analysis of a shell-tube heat exchanger with spiral bend tubes

The porous media model was improved to simulate the flow field of a shell-tube heat exchanger with spiral bend tubes. The improved porous medium model can be used to control the fluid flow direction. On the tube side, the streamline was along the spiral bend tubes. The fluid velocities and pressure drops on the tube and shell sides agree well with the experimental values. The fluid flow on the shell side is little affected by the spiral bend structure. The thermal stress of the spiral bend tubes was analyzed. The thermal stress of the spiral bend tubes is much smaller than the thermal stress of the straight tube. The thermal stress at the bend part decreases with the increase of bending angles.

Design and comparison study of steam generator concepts and power conversion cycles for fusion reactors

Abstract While the viability of fusion energy would be demonstrated by the ITER operation, the power extraction from the fusion reactors also needs attention in parallel as it presents its own challenges due to the specific features of tokamaks. A detailed comparison study on different steam generators being used in fission reactors and their viability in fusion reactors has been addressed with the primary and secondary fluids being considered as helium and water respectively. Based on the comparison, the shell & tube heat exchanger (STHE) and the printed circuit heat exchangers (PCHE) have been considered as the potential candidates, assuming 500 MWTh power. The comparative investigations of Brayton and Rankine power cycle along with their efficiencies are also discussed. The Rankine cycle gives 36 % and 38 % efficiency for the STHE and PCHE cases, respectively, whereas that of Brayton gas cycle efficiency is 42 % for PCHE.

Flow Prediction and Conjugate Heat-Transfer Analysis of a Counter Flow Heat-Exchanger with Protruded Fin

Voluminous cram has been carried out in this project which is intended to improve the conjugate heat-transfer performance of a heat-exchanger. In this study, CFD method is effectively used to predict the effect of Protruded Fins in heat exchanger, which protrudes inside the tube in addition to the shell side. CFD analysis on Protruded Finned Heat Exchanger (PFHE) is carried out with three different fin configurations like rectangular, triangular and parabolic fins. The baseline model of counter flow shell-tube heat-exchanger is considered with standard dimensions and analyzed initially without fins. Later the numbers of fins are increased to optimize the fin position and counts. The shape of the fins is then modified to find an optimized model with a higher heat-transfer coefficient. Hence, the present conjugate heat-transfer and flow analysis focus on optimizing the number of fins for a heat-exchanger with counter flow along with the shape optimization of fins. The computational values are measured with the net heat exchange between the cold and hot-fluids in terms of temperature difference. Also, the area averaged surface heat transfer co-efficient (h) of the heat exchanger with different fin configurations are plotted and compared.

Performance Enhancement of Shell–Tube Heat Exchanger by Clamping Anti-Vibration Baffles with Porous Media Involvement

The enhancement with porous media involvement is estimated and compared for three varieties of shell and tube heat exchangers (STHXs), with helical, segmental and clamping anti-vibration baffles, with two variations, viz., porosity value and dimension of this media (radius). In this study, further improvement in the thermo-hydraulic performance of the anti-vibration baffles design of STHX was investigated using simulation, with porous media inclusion. The inclusion of porous medium in the shell side is in a way that the whole tube bundle is wrapped by it; inside the tubes, porous media are located in two ways: (1) at the center of tubes and (2) fixed to the inner lining of the tubes. The findings suggest that the porous media improve the heat transfer with the expense of pressure drop; it is also noted, of all the cases, the pressure drop is minimum in anti-vibrational baffles. The analysis showed that using porous media with specific porosity and dimension can increase heat transfer rate along with less pressure drop. For the clamping anti-vibration baffles STHX, enhanced and overall effective performance was found with porous media inclusion of 0.6 porous radius ratio and porosity of 0.6.

Improvement in Energy Performance of Tubular Heat Exchangers Using Nanofluids: A Review

Both mono and hybrid nanofluids, the engineered colloidal mixture made of the base fluid and nanoparticles, have shown many interesting properties and become a high potential nextgeneration heat transfer fluids in various heat exchangers for engineering applications. The present review focuses on improving the performance of tubular heat exchangers by using nanofluids. For this, the present review briefly summarizes the preparation, characterization and thermophysical properties (thermal conductivity, viscosity, specific heat capacity and density) of mono and hybrid nanofluids. Research works on heat transfer and pressure drop characteristics of nanofluids in the double tube and shell-tube heat exchangers with both straight and coiled tubes, and various engineering applications (power generation, refrigeration and air-conditioning, renewable energy, domestic cooling or heating, etc.) are well-grouped and thoroughly discussed. Physical mechanisms for the heat transfer enhancement using nanofluids are explored as well. Most of the studies reveal that there are significant enhancements in the heat transfer process and in the effectiveness of both straight and coiled tube heat exchangers with a slight increase in pressure drop using nanofluids. Hence, there is an excellent opportunity to use nanofluids in tubular heat exchangers; however, high cost (high payback period) and stability are the main challenges for practical implementation. Finally, some useful recommendations are also provided.

Identifying naphthenic acid corrosion mechanism on heat exchanger unit by computational fluid dynamic simulation

Corrosion in refinery assets is complex which involves multi factors contributing to damage mechanisms. The present study aims to evaluate the damage mechanism which caused the heat exchanger (HEX) to leak in parallel sequence. In this sense, experiments were conducted to investigate the correlation between convective heat transfer coefficients and reveals the correlation with material degradation in the heat exchanger. Failure analysis was concluded HEX was attacked by naphthenic acid corrosion (NAC) due to sharp-edged, crater-like holes to sharp-edged streamlined grooves with corrosion product consist of sulphide. Material behaviour analysis assisted by computerized fluid dynamics (CFD) software strongly suggested that the inhibitor is not well distributed at the location of 356 mm because the velocity distribution at the specific location of the corrosive tubes was not uniform. Parallel failure initiated in the distribution of inhibitor and heat in HEX using CFD. From the results of the research, it can be concluded that the selection of material needs to be upgraded to at least 9% molybdate alloying content. CFD results reveal the optimum temperature and pressure of heat exchanger to control NAC attack as well as failure associated with the impact of stream detachment inside the bay to a few tubes. Overall results reveal the CFD method is suitable in predicting the fluid flow and thermal condition at the location of the corrosion failure in the shell tube heat exchanger. The location of corrosion can also be identified and the streamline of flow can be visualized by other materials failure analysis techniques.

Investigation of Shell and Tube Heat Exchanger with Disc-and-Doughnut Baffles

Disk and doughnut baffles configuration for shell tube heat exchangers (STHXs) is one of the solutions for compensating the higher pressure drop penalty induced by conventional segmental baffles. Furthermore, absently reliable references for the optimum design of this type of STHXs are our main purpose to carry out this investigation. From modeling numerical simulation results, with 7 baffles and 70% baffles ratio geometrical dimension is suggested the optimum configuration of this type of heat exchange. Additionally, the characteristic of heat transfer performance is discussed by varying the flow velocity in all different flow regimes of shell and tube side respectively through conducting the experimental apparatus. Hopefully this result could provide validating information in optimum design of STHXs with disk and doughnut baffles.

Leakage Analysis on Non-axisymmetric Gasket of the Shelltube Heat Exchanger Header

This paper focuses the flanged static sealing structure of shell-tube heat exchange header, builds an static sealing model based on FEM(Finite Element Method),studies the effect of bolt preload and working medium load on the gasket actual contact stress. The results indicate that: an approximately linear relationship exists among the gasket contact stress, bolt preload and working medium load. When the pressure is gradually increasing, the flat end-plate’s outward convex deformation results in the decreasing gasket stress in the center and even leakage. After locating the above leakage reason, the flange gasket structure is improved, and the bolt distribution and bolt preload is adjusted accordingly. The problem of leakage has been solved, approves that the calculating method of gasket sealing is an effective approach.

Improved thermal performance of annular fin-shell tube storage system using magnetic fluid

The main contribution of this paper is achieving a significant thermal performance improvement of annular fins-shell-tube heat exchanger energy storage system using magnetic fluid. The fin efficiency is increased by 20% with annular fin-magnetic fluid geometry as compared to without magnetic fluid. This improvement in thermal characteristics of annular fin system can be attributed to the formation of nano-channels in the field directions and effective increase in overall heat transfer coefficient due to the replacement of solid-gas interface with the liquid-gas interface. This replacement leads to improved convective heat transfer rate and overall thermal characteristics, which is the new knowledge contribution for various energy storage systems. In the present work, a simple and novel method for improving the thermal performance of natural convection energy storage system is reported. This novel method can improve the overall performance of the systems with natural convection extended surfaces and makes it suitable for numerous heat transfer applications. A magnetic fluid thin layer association with annular fin geometry has been proposed to improve the shell-tube heat exchangers performance, and an in-house experimental setup is used to study its dimensional and non-dimensional heat transfer characteristics. Kerosene and water-based MF were prepared by chemical co-precipitation method and employed on the top surface of the fin to maximise the heat transfer rate and to increase the effectiveness (ε) of the fin system. This thin layer of MF was maintained on the top surface of the fins using the magnetic ring of small NdFeB magnet of 1 mm thickness and 2.5 mm diameter. It is observed that a significant increase in relative heat transfer rate (∼35%) taking place using a thin MF layer over the top surface of the fin which leads to enhancement in fin performance. Also, the temperature distribution along the length of the fin shows a sharp decrease in temperature near the top surface which corroborates our observations that the magnetic ring over the surface works as a chill block which provides a directional cooling through magnetic nano-channels. These new findings can be valuable in the design of an efficient annular fin-shell tube latent heat exchanger storage system.

Experimental investigation of an adjustable standing wave thermoacoustic engine

This work is primarily concerned with the experimental investigation of the performance of a standing wave thermoacoustic engine (TAE). The TAE technology converts thermal power into acoustic power which may be used to generate electricity or, to drive thermoacoustic cooling devices. Although there is a number of existing researches that suggest the link between the geometrical configuration of the device and its performance, there are no existing work that point out how to incorporate this aspect in the designing. Therefore, this study proposes the use of an adjustable TAE in order to alter the performance of the device while in operation. This new TAE model has an adjustable resonator length, which consisted of a 103 mm (4-in.) honeycomb ceramic stack sample, buffer volume and a cooling shell-tube heat exchanger was developed. Six different stacks were used to evaluate the performance of the TAE. Three different stack lengths (50, 100, and 150 mm), positioned at three different locations, were investigated. These locations were measured from the hot ends of the stack to the pressure antinode. In addition, the influence of the mean pressure and the working gas was investigated. Measurement of temperature difference across the stack and sound pressure levels at the steady state were used to determine the efficiency of the device. Through the adjustment of the resonator length, this study point out the benefit of choosing the best frequency so that TAE can work optimally and produce higher acoustic power.

A novel defrosting method in gasoline vapor recovery application

Condensation method is comprehensively applied for gasoline vapor recovery (GVR), of which frosts in the heat exchanger is the greatest challenge, especially for the continuous long running cases. A novel dual channel GVR cascade refrigeration system with shell-tube heat exchanger was presented and tested in this paper. With one-work-one-standby evaporator settings, combined with refrigerant evacuation and delay switching strategies, the defrosting of low temperature shell-tube heat exchanger was analyzed and solved. Also multi-stage cycle was introduced to supply three cooling stage, which cooled the gasoline vapor from ordinary temperature to about −70 °C. By the means of industrial application validation and process calculation, the ability of the non-stop cooling during defrosting was verified. The refrigerant evacuation was proposed to prevent high pressure drop caused by frost accumulation, which also improved the cooling capacity by 28.2% and approached the defrost efficiency of 55.4%. In addition, it was found that delay switching can effectively reduce the capacity fluctuation. Based on sensitivity studies, 20 min delay was identified as the best switching timing for this device. The capacity of this system performed lower reduction, higher duty ratio and defrost efficiency.

Experimental investigation of an adjustable thermoacoustically-driven thermoacoustic refrigerator

An experimental investigation is conducted on a new adjustable thermoacoustically-driven thermoacoustic refrigerator (TADTAR). This refrigerator comprises of a thermoacoustic engine which drives a thermoacoustic refrigerator. This study aims to demonstrate the possibility to alter the TADTAR performance through the adjustment of specific design parameters. An adjustable resonator, which consisted of stacks, spacing couplings and shell-tube heat exchangers was designed and built. Six different honeycomb ceramic stacks were investigated. For each system, three different stack configurations were studied. Measurements of temperature difference across the refrigerator stack and sound pressure levels at steady states were used to determine the performance of the device. Through the adjustment of the length and the insertion of the heat exchanger, the performance of the device with a longer resonator was relatively higher. This study shows that an adjustable resonator successfully alters the frequency output of the thermoacoustic engine to match the frequency required by the thermoacoustic refrigerator and achieve resonance. In addition, this study demonstrates the possibility to change the geometrical configuration of the device and ultimately alter the performance of the TADTAR. Through the adjustment of the length of the resonator, this study shows that a single device could have different operating points. This creates new possibilities to introduce control system able to adjust the geometry of thermoacoustic system while in operation.

Чисельне моделювання теплообмінного апарата для різних систем вентиляції

The purpose of the research is to develop and numerical modeling of the shell-tube heat exchanger of a new design as an element of the microclimate maintenance system for various types of ventilation systems in the summer season. Materials and methods of research. As mentioned above, two types of ventilation systems are considered - tunnel and lateral. For these ventilation systems TA is projected. The poultry house is a traditional type. At the side walls there are openings with jackets in the total number of 80 pieces. with dimensions 0,3×0,85 m. And also on the front end walls are located evacuation cooling tapes with dimensions of 5,1×1,1 m. In place of the cassettes and louver we fit the HE. Consider the shell and tube heat exchanger with a shell of a rectangular cross section in the transverse flow of pipe beams. The geometry of the pipes with diameters d = 10 mm is peculiar, which differs from the traditional chess, corridor and compact beams. Neighboring pipes in such close beams are displaced one relative to the other at a distance of 1 mm. Moreover, we consider two types of beam construction, in which there is a displacement of pipes in a transverse direction along the entire length of the tube beam by 15 mm. All calculations are performed at a volume flow of air 1036 thousand m3/h. As a coolant air is selected with a temperature of +40 o С at the inlet, which flows in the channels for cooling the external heated air in the poultry house in the summer period of the year, where as the cooler is used water underground wells. In the soybean, cold water moving inside the pipes, which has an inlet temperature of +10 o C. The layout of the heat carrier movement is cross-linked. Research results and their discussion. The temperature change for different ventilation systems. For tunnel ventilation, the temperature in the TA decreases from +40 to +22.5 o C (Fig. 2), and for the side - from +40 to +19,7 o С. Conclusions and perspectives. 1. A new design of a shell-tube heat exchanger with a compact arrangement of pipes in tubular beams is proposed and developed. 2. Computer-aided mathematical modeling of heat and mass transfer processes in bundles of pipes of different geometries with compact placement of pipes using the software ANSYS Fluent. The fields of velocities, temperatures, and pressure in the studied channels are obtained. The conditions of the hydrodynamic flow in the channels were analyzed and estimates of the heat transfer intensity between the hot and cold coolant through the wall separating them. 3. It was determined that the tunnel ventilation system would be most effective and TA was designed for it.

Determination of Repair Weld Residual Stress in a Tube to Tube-Sheet Joint by Neutron Diffraction and the Finite Element Method

Repair welding is a popular method to repair the leakage zone in tube-to-tubesheet joint of shell-tube heat exchangers. But the repaired residual stresses are generated inevitably and have a great effect on stress corrosion cracking (SCC). In this paper, the effects of repair welding on residual stress were studied by finite element method (FEM) and neutron diffraction measurement. The original weld residual stresses calculated by FEM showed good agreement with neutron diffraction measurement results. After repair welding, the transverse residual stresses change very little while the longitudinal residual stresses are increased in the repair zone. In the nonrepair zone, both the transverse and longitudinal stresses are decreased. The repair welding times have little effect on residual stress distribution. With the increase of welding length and heat input, the residual stresses increase. Repair opposite to the original welding direction is recommended because the opposite welding direction minimizes the residual stresses.