scholarly journals NUMERICAL ANALYSIS OF INDIRECT ICE STORAGE SYSTEMS PERFORMANCE

2006 ◽  
Vol 5 (1) ◽  
pp. 84
Author(s):  
C. S. Stampa ◽  
A. O. Nieckele
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Storage Tank ◽  
Storage Systems ◽  
Exchange Process ◽  
Vertical Position ◽  
Ice Storage ◽  
Flat Plates ◽  
Thermal Exchange ◽  
Process Behavior

A numerical investigation regarding the charging process behavior occurring in a typical indirect ice storage tank is presented. It consists of analyzing the heat transfer and removal of energy, applicable to storage systems, which are chiller-based. In this sense the secondary coolant circulates through a heat exchanger that is submerged in a tank of water and it is used to freeze (charge) the phase-change material (water), which never leaves the storage tank. The thermal exchange process is investigated considering the storage tank in two different positions. In the first one the storage tank is in the vertical position, while for the second, it is horizontally positioned. The storage tank is represented by a channel formed by parallel flat plates, one of which is the heat exchanger. Our task is to provide helpful qualitative results for the heat transfer performance of ice storage tanks. The results are analysed through streamlines and isotherms, for specific instants of time. Further, the heat transfer effectiveness, average heat flux and solid formed at one of the two plates of the channel, are compared for the vertical and horizontal positions of the channel.

A Numerical Study Concerning Indirect Ice Storage Tanks Performance

2004 ◽  
Author(s):  
Cleyton S. Stampa ◽  
Angela O. Nieckele
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Storage Tank ◽  
Numerical Study ◽  
Exchange Process ◽  
Vertical Position ◽  
Ice Storage ◽  
Tank Wall ◽  
Storage Tanks ◽  
Flat Plates

A numerical investigation regarding the charging process behavior occurring in a typical indirect ice storage tank is presented. It consists of analyzing the heat transfer and removal of energy, applicable to storage systems, which are chiller-based. In this sense the secondary coolant circulates through a heat exchanger that is submerged in a tank of water and it is used to freeze (charge) the phase-change material (water), which never leaves the storage tank. The thermal exchange process is investigated in critical regions formed between the heat exchanger wall and the tank wall. The present study simulates such regions through a channel formed by parallel flat plates, one of which is the heat exchanger, and investigates the heat transfer effects considering it in two different positions. In the first one the channel is in the vertical position, while for the second, it is horizontally positioned. Our task is to provide helpful qualitative results for the heat transfer performance of ice storage tanks. The results are analyzed through streamlines and isotherms, for specific instants of time. Further, the heat transfer effectiveness, average heat flux and solid formed at one of the two plates of the channel, are compared for the vertical and horizontal positions of the channel, as well as different distances from the heat exchanger and tank wall.

Calculation and Design Method Study of the Coil-Wound Heat Exchanger

2014 ◽  
Vol 1008-1009 ◽  
pp. 850-860 ◽  
Author(s):  
Zhou Wei Zhang ◽  
Jia Xing Xue ◽  
Ya Hong Wang
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Heat Exchanger ◽  
Design Method ◽  
Fluid Velocity ◽  
Exchange Process ◽  
Three Dimensional ◽  
Simulation Method ◽  
Physical Parameters ◽  
Numerical Result

A calculation method for counter-current type coil-wound heat exchanger is presented for heat exchange process. The numerical simulation method is applied to determine the basic physical parameters of wound bundles. By controlling the inlet fluid velocity varying in coil-wound heat exchanger to program and calculate the iterative process. The calculation data is analyzed by comparison of numerical result and the unit three dimensional pipe bundle model was built. Studies show that the introduction of numerical simulation can simplify the pipe winding process and accelerate the calculation and design of overall configuration in coil-wound heat exchanger. This method can be applied to the physical modeling and heat transfer calculation of pipe bundles in coil wound heat exchanger, program to calculate the complex heat transfer changing with velocity and other parameters, and optimize the overall design and calculation of spiral bundles.

Upgrade and Shakedown Test of a High Temperature Fluoride Salt Test Loop

2018 ◽  
Author(s):  
Xiangbo Kong ◽  
Yuan Fu ◽  
Jianyu Zhang ◽  
Huiju Lu ◽  
Naxiu Wang
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Heat Exchanger ◽  
Flow Rate ◽  
Storage Tank ◽  
Base Alloy ◽  
High Vacuum ◽  
Electric Heater ◽  
Batch Mode ◽  
Test Loop

A FLiNaK high temperature test loop, which was designed to support the Thorium Molten Salt Reactor (TMSR) program, was constructed in 2012 and is the largest engineering-scale fluoride loop in the world. The loop is built of Hastelloy C276 and is capable of operating at the flow rate up to 25m3/h and at the temperature up to 650°C. It consists of an overhung impeller sump-type centrifugal pump, an electric heater, a heat exchanger, a freeze valve and a mechanical one, a storage tank, etc. Salt purification was conducted in batch mode before it was transferred to and then stored in the storage tank. The facility was upgraded in three ways last year, with aims of testing a 30kW electric heater and supporting the heat transfer experiment in heat exchanger. Firstly, an original 100kW electric heater was replaced with a 335kW one to compensate the overlarge heat loss in the radiator. A pressure transmitter was subsequently installed in the inlet pipe of this updated heater. Finally, a new 30kW electric heater was installed between the pump and radiator, the purpose of which was to verify the core’s convective heat transfer behavior of a simulator design of TMSR. Immediately after these above works, shakedown test of the loop was carried out step by step. At first the storage tank was gradually preheated to 500°C so as to melt the frozen salt. Afterwards, in order to make the operation of transferring salt from storage tank to loop achievable, the loop system was also preheated to a relatively higher temperature 530°C. Since the nickel-base alloy can be severely corroded by the FLiNaK salt once the moisture and oxygen concentration is high, vacuum pumping and argon purging of the entire system were alternatively performed throughout the preheating process, with the effect of controlling them to be lower than 100ppm. Once the salt was transferred into the loop, the pump was immediately put into service. At the very beginning of operation process, it was found that flow rate in the main piping could not be precisely measured by the ultrasonic flow meter. Ten days later, the pump’s dry running gas seal was out of order. As a result, the loop had to be closed down to resolve these issues.

Integrity of Old Pipelines Buried in Petroleum Products Storage Terminals

2008 ◽  
Author(s):  
Mauro Y. Fujikawa ◽  
Eduardo O. de A. Silva ◽  
Reinaldo A. das Neves ◽  
Derci Donizeti Massitelli ◽  
Newton Orlando Abraha˜o ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Storage Tank ◽  
High Viscosity ◽  
Petroleum Products ◽  
The Other ◽  
Fuel Oil ◽  
Marine Fuel ◽  
Analysis Study ◽  
Theoretical Results

This work aims to present the results obtained from the experience gained through the accomplishment of the inspection with the ultrasonic umbilical pig in a non-piggable internal pipe buried in the Transpetro Storage Terminal in Sa˜o Caetano do Sul, in Sa˜o Paulo, Brazil. The pipeline considered in this work is a line for marine fuel oil, which, because of its high viscosity, must be heated in order to flow. The oil is heated in the terminal by the steam produced in boilers. The heat transfer may occur in a heat exchanger or inside the storage tank, and the pipeline referred is thermally isolated. So that the line could be inspected, it was divided in two parts, one upstream of the pumps (suction), which is a 12-inch line, and the other downstream of the same pumps (discharge), which is a 14-inch line. This work has been developed by Transpetro’s Pipeline Operation, Maintenance, Inspection and Safety Departments together, since the planning phase, passing by the job execution and getting to the conclusion. To begin with, the operational liberation of the line had to be agreed between all the departments involved with the PIG inspection, which were mentioned before, and Transpetro’s Logistics Department. Once the PIG passage was scheduled, an initial cleaning had to be performed by the Operation Activity. Since this line is non-piggable, the installation of adaptations was necessary. After that, the passage of cleaning PIGs was possible, and the line sections could be enabled. The next step was the inspection of the pipeline with umbilical ultrasonic PIGs. After the passage of these PIGs, the adaptations had to be removed and the pipeline had to be conditioned for the operational return. After this part of the inspection was finished, the verification of the results issued was necessary. Once the theoretical results were available, ditches were opened for correlation inspection and temporary repairs in the most critical points for the operation were applied. The last part of the work consists in an analysis study of technical and economical viability for rehabilitation of the lines.

scholarly journals Enhancing Heat Transfer in Tube Heat Exchanger by Inserting Discrete Twisting Tapes with Different Positions

2019 ◽  
Vol 25 (8) ◽  
pp. 39-51
Author(s):  
Nassr Fadhil Hussein ◽  
Abdulrahman Shakir Mahmood
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Constant Heat Flux ◽  
Vertical Position ◽  
Maximum Heat ◽  
Tube Heat Exchanger ◽  
Twisted Tapes ◽  
Maximum Heat Transfer

Enhancement of heat transfer in the tube heat exchanger is studied experimentally by using discrete twisted tapes. Three different positions were selected for inserting turbulators along tube section (horizontal position by α= 00, inclined position by α= 45 0 and vertical position by α= 900). The space between turbulators was fixed by distributing 5 pieces of these turbulators with pitch ratio    PR = (0.44). Also, the factor of constant heat flux was applied as a boundary condition around the tube test section for all experiments of this investigation, while the flow rates were selected as a variable factor (Reynolds number values vary from 5000 to 15000). The results show that using discrete twisted tapes enhances the heat transfer rate by about 60.7-103.7 % compared with plane tube case. Also, inserting turbulators with inclined position offers maximum heat transfer rate by 103.7%.  

A Numerical Parametric Study of the Growth of Ice Formation Around a Vertical Tube, During the Full Charging Process of an Indirect, Area-Constrained, Ice-on-Pipe Storage Tank

2003 ◽  
Author(s):  
Cleyton S. Stampa ◽  
Angela O. Nieckele ◽  
Sergio L. Braga
Keyword(s):  
Heat Transfer ◽  
Storage Tank ◽  
Vertical Wall ◽  
Vertical Tube ◽  
Layer Growth ◽  
Ice Storage ◽  
Vertical Annulus ◽  
Numerical Parametric Study ◽  
Volume Method ◽  
The Mathematical Model

A parametric numerical investigation regarding the ice layer growth outside a vertical tube is investigated. It encompasses heat transfer and removal of energy, applicable to indirect, area-constrained, ice-on-pipe storage tanks. The study is carried out in a vertical annulus, with the inner vertical wall representing one of the tubes packed into a typical storage tank. Further, the outer vertical wall determines the maximum border for the ice layer growth under the conditions established in the present study, corresponding to a full charging process in such devices. Our task is to provide helpful qualitative results for the investigation of ice storage tank heat transfer performance, considering changes in the following parameters: aspect ratio, radius ratio, Grashof and Stefan numbers. For the mathematical model adopted to simulate transient natural convection of water with phase-change (solidification), it was utilized a model based on the finite volume method to solve the set of coupled conservation equations of mass, momentum and energy.

Use of a Shroud and Baffle to Improve Natural Convection to Immersed Heat Exchangers

2010 ◽  
Author(s):  
S. K. S. Boetcher ◽  
F. A. Kulacki ◽  
Jane H. Davidson
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Storage Tank ◽  
High Performance ◽  
Discharge Process ◽  
Thermal Systems ◽  
Water Storage Tank ◽  
Nusselt Numbers ◽  
Commercial Applications ◽  
Thermal Stores

Optimizing heat transfer during the charge and discharge of thermal stores is crucial for high performance of solar thermal systems for domestic and commercial applications. This study models a sensible water storage tank for which charge and discharge are accomplished using a heat exchanger immersed in the storage fluid. The objective is to investigate the use of a baffle and shroud as a means to improve convective heat transfer and thermal stratification. The immersed heat exchanger is modeled as a two-dimensional isothermal cylinder which is situated near the top of a storage tank with adiabatic walls. Transient numerical simulations of the discharge process are obtained for 105 < RaD < 107. An adiabatic shroud and baffle whose geometry is parametrically varied is placed around and below the cylinder. Transient Nusselt numbers are calculated for different baffle-shroud geometries and Rayleigh numbers. Results indicate that a long baffle with a high shroud height is optimal.

A Numerical Study Concerning the Influence of the Grashof Number in the Indirect Ice Storage Tanks Performance

2006 ◽  
Author(s):  
Cleyton S. Stampa ◽  
Angela O. Nieckele
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Phase Change ◽  
Flow Pattern ◽  
Storage Tank ◽  
Vertical Wall ◽  
Heat Transfer Analysis ◽  
Ice Storage ◽  
Storage Tanks ◽  
Grashof Number

The present paper deals with typical chiller-based ice storage tanks. Natural convection of water (Phase Change Material-PCM) near its density maximum leads to a peculiar nature of the flow pattern in the liquid phase of the PCM, giving rise to a multi-cellular regime that affects drastically the heat transfers within the tank. So, this work intends to examine numerically how the flow pattern affects qualitatively the performance of such thermal storage devices. This is done by investigating the influence of the non-dimensional parameter Grashof number during the charging operation step of such devices that corresponds to the ice making process occurring within the storage tank. Besides, the tank is assumed to be vertically positioned, as well as their internal tubes through which the secondary fluid flows. In order to analyze the heat transfer between the PCM and one internal tube during the growth of an ice layer around it, one selected a vertical annulus as the physical model. The inner vertical wall represents one of the tubes packed into a typical storage tank, while the outer vertical wall represents the thickness of formed ice around the tube. Regarding the annulus, the top and bottom walls, as well as the outer vertical wall were considered thermally insulated. The thermal analysis is focused in the heat transfer at the inner wall for different values of Grashof, keeping unchanged all other parameters that govern the natural convection problem with phase change. An overview of the cooling process is analyzed through streamlines and isotherms, for specific instants of the physical process. Further, a heat transfer analysis for the total charging stage is presented.

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