Modeling of Supercritical Co2 Shell-and-Tube Heat Exchangers Under Extreme Conditions. Part 1: Correlation Development

2022 ◽  
Author(s):  
Akshay Bharadwaj Krishna ◽  
Kaiyuan Jin ◽  
Portnovo Ayyaswamy ◽  
Ivan Catton ◽  
Timothy S. Fisher
Keyword(s):  
Heat Exchangers ◽  
Supercritical Co2 ◽  
Multivariate Regression ◽  
Electric Propulsion ◽  
Multivariate Regression Analysis ◽  
Working Fluid ◽  
Data Sets ◽  
Cfd Simulations ◽  
Shell And Tube ◽  
Critical Components

Abstract High-temperature supercritical CO2 Brayton cycles are promising possibilities for future stationary power generation and hybrid electric propulsion applications. Heat exchangers are critical components in supercritical CO2 thermal cycles and require accurate correlations and comprehensive performance modeling under extreme temperatures and pressures. In this paper (part I), new Colburn and friction factor correlations are developed to quantify shell-side heat transfer and friction characteristics of flow within heat exchangers in the shell-and-tube configuration. Using experimental and CFD data sets from existing literature, multivariate regression analysis is conducted to achieve correlations that capture the effect of multiple critical geometric parameters. These correlations offer superior accuracy and versatility as compared to previous studies and predict the thermohydraulic performance of about 90% of the existing experimental and CFD data within ±15%. Supplementary thermohydraulic performance data is acquired from CFD simulations with sCO2 as working fluid to validate the developed correlations and demonstrate its capability to be applied to sCO2 heat exchangers.

scholarly journals Study on Shell-and-Tube Heat Exchanger Models with Different Degree of Complexity for Process Simulation and Control Design

2018 ◽  
Author(s):  
Javier Bonilla
Keyword(s):  
Heat Exchanger ◽  
Molten Salt ◽  
Heat Exchangers ◽  
Control Strategies ◽  
Thermal Storage ◽  
Working Fluid ◽  
Tube Heat Exchanger ◽  
Test Loop ◽  
Shell And Tube ◽  
Thermal Oil

Many commercial solar thermal power plants rely on indirect thermal storage systems in order to provide a stable and reliable power supply, where the working fluid is commonly thermal oil and the storage fluid is molten salt. The thermal oil - molten salt heat exchanger control strategies, to charge and discharge the thermal storage system, strongly affect the performance of the whole plant. Shell-and-tube heat exchangers are the most common type of heat exchangers used in these facilities. With the aim of developing advanced control strategies accurate and fast dynamic models of shell-and-tube heat exchangers are essential. For this reason, several shell-and-tube heat exchanger models with different degrees of complexity have been studied, analyzed and validated against experimental data from the CIEMAT-PSA molten salt test loop for thermal energy systems facility. Simulation results are compared in steady-state as well as transient predictions in order to determine the required complexity of the model to yield accurate results.

scholarly journals Modelling of Polymeric Shell and Tube Heat Exchangers for Low-Medium Temperature Geothermal Applications

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2737
Author(s):  
Francesca Ceglia ◽  
Adriano Macaluso ◽  
Elisa Marrasso ◽  
Maurizio Sasso ◽  
Laura Vanoli
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Power Plants ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Heat Transfer Area ◽  
Geothermal Fluid ◽  
Shell And Tube

Improvements in using geothermal sources can be attained through the installation of power plants taking advantage of low and medium enthalpy available in poorly exploited geothermal sites. Geothermal fluids at medium and low temperature could be considered to feed binary cycle power plants using organic fluids for electricity “production” or in cogeneration configuration. The improvement in the use of geothermal aquifers at low-medium enthalpy in small deep sites favours the reduction of drilling well costs, and in addition, it allows the exploitation of local resources in the energy districts. The heat exchanger evaporator enables the thermal heat exchange between the working fluid (which is commonly an organic fluid for an Organic Rankine Cycle) and the geothermal fluid (supplied by the aquifer). Thus, it has to be realised taking into account the thermodynamic proprieties and chemical composition of the geothermal field. The geothermal fluid is typically very aggressive, and it leads to the corrosion of steel traditionally used in the heat exchangers. This paper analyses the possibility of using plastic material in the constructions of the evaporator installed in an Organic Rankine Cycle plant in order to overcome the problems of corrosion and the increase of heat exchanger thermal resistance due to the fouling effect. A comparison among heat exchangers made of commonly used materials, such as carbon, steel, and titanium, with alternative polymeric materials has been carried out. This analysis has been built in a mathematical approach using the correlation referred to in the literature about heat transfer in single-phase and two-phase fluids in a tube and/or in the shell side. The outcomes provide the heat transfer area for the shell and tube heat exchanger with a fixed thermal power size. The results have demonstrated that the plastic evaporator shows an increase of 47.0% of the heat transfer area but an economic installation cost saving of 48.0% over the titanium evaporator.

Enhancement of Convective Heat Transfer in Internal Viscous Flows by Inserting Motionless Mixers

2009 ◽  
Author(s):  
Ramin K. Rahmani ◽  
Anahita Ayasoufi ◽  
Theo G. Keith
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Turbulent Flows ◽  
Heat Exchangers ◽  
Convection Heat Transfer ◽  
Viscous Fluids ◽  
High Rate ◽  
Working Fluid ◽  
Static Mixer ◽  
Shell And Tube

In chemical processing industries, heating, cooling and other thermal processing of viscous fluids are an integral part of the unit operations. Enhancement of the natural and forced convection heat transfer rates has been the subject of numerous academic and industrial studies. Motionless mixers, also known as static mixers, are often used in continuous mixing, heat transfer, and chemical reactions applications. These mixers have low maintenance and operating costs, low space requirements, and have no moving parts. Heat exchangers equipped with mixing elements are especially well suited for heating or cooling highly viscous fluids. Shell and tube heat exchangers incorporate static mixing elements in the tubes to produce a heat transfer rate significantly higher than that of conventional heat exchangers. The mixing elements continuously create a new interface between the working fluid and tube wall, thereby producing a uniform heat history in the fluid. It is desired to employ motionless mixers in heat transfer applications to provide a high rate of heat transfer from a thermally homogenous fluid with low pressure drop. In the past, laboratory experimentation has been a fundamental part of the design process of a new static mixer for a given application as well as the selection of an existing static mixer. It is possible to use powerful computational fluid dynamics (CFD) tools to study the performance of these mixers without resorting to experimentation. In this paper, which is an extension to the previous work of the authors, the enhancement of performance of shell and tube heat exchangers by inserting motionless mixers (SMX and helical) is studied for creeping, laminar, and low-Re turbulent flows. It is shown that the studied mixers produced similar flow histories for the working fluid considered. Both SMX and helical mixers are able to increase thermal performance of heat exchangers. The SMX mixer manifests a higher performance in temperature blending and in heat transfer enhancement compared to the helical mixer. However, the pressure drop created by SMX elements, and consequently the required energy to maintain the flow in tube, is significantly higher.

Modeling of Supercritical Co2 Shell-and-Tube Heat Exchangers Under Extreme Conditions. Part 2: Heat Exchanger Model

2022 ◽  
Author(s):  
Akshay Bharadwaj Krishna ◽  
Kaiyuan Jin ◽  
Portnovo Ayyaswamy ◽  
Ivan Catton ◽  
Timothy S. Fisher
Keyword(s):  
Heat Exchanger ◽  
Numerical Model ◽  
Heat Exchangers ◽  
Supercritical Co2 ◽  
Critical Role ◽  
Computation Time ◽  
Efficient Estimation ◽  
Working Fluid ◽  
Computationally Efficient ◽  
Thermal Cycles

Abstract Heat exchangers play a critical role in supercritical CO2 Brayton cycles by providing necessary waste heat recovery. Supercritical CO2 thermal cycles potentially achieve higher energy density and thermal efficiency operating at elevated temperatures and pressures. Accurate and computationally efficient estimation of heat exchanger performance metrics at these conditions is important for the design and optimization of sCO2 systems and thermal cycles. In this paper (Part II), a computationally efficient and accurate numerical model is developed to predict the performance of STHXs. Highly accurate correlations reported in Part I of this study are utilized to improve the accuracy of performance predictions, and the concept of volume averaging is used to abstract the geometry and reduce computation time. The numerical model is validated by comparison with CFD simulations and provides high accuracy and significantly lower computation time compared to existing numerical models. A preliminary optimization study is conducted and the advantage of using supercritical CO2 as a working fluid for energy systems is demonstrated.

Techno-economic analysis of nitrogen-doped graphene/water nanofluid in various heat exchangers (A unified analysis)

2021 ◽  
pp. 095765092110521
Author(s):  
Yousif M Alkhulaifi ◽  
Shahzada Zaman Shuja ◽  
Bekir Sami Yilbas
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Working Fluid ◽  
Heat Transfer Area ◽  
Plate Heat ◽  
Nitrogen Doped ◽  
Nitrogen Doped Graphene ◽  
Doped Graphene ◽  
Shell And Tube ◽  
Double Pipe

Nitrogen-doped graphene (NDG)/water nanofluid is one of the emerging working fluids toward achieving high heating rates in heat transfer devices. In the present study, thermal performance improvement and techno-economic analysis of a double pipe, shell and tube, and plate heat exchangers are presented while incorporating NDG/water nanofluid as a working fluid. The variable properties of NDG nanofluid are incorporated and the influence of nanoparticle concentrations and mass flow rates on the device thermal performance and related costs are evaluated. The findings demonstrate that device heat transfer area and costs are adversely affected by using NDG/water nanofluid in all types of heat exchanging devices considered. An increase in heat transfer area is associated with the decrease of the specific heat capacity of the working fluid. The increase of heat transfer area can be as high as 58.5%, 45.1%, and 67.0% for double pipe, shell and tube, and plate heat exchangers, respectively. In addition, area increase becomes persistent with other types of nanoparticles used in the carrier fluid.

Additional Power Generation From Waste Energy of Diesel Engine Using Parallel Flow Shell and Tube Heat Exchanger

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Shekh N. Hossain ◽  
S. Bari
Keyword(s):  
Power Generation ◽  
Heat Exchanger ◽  
Diesel Engine ◽  
Heat Exchangers ◽  
Parallel Flow ◽  
Working Fluid ◽  
Exhaust Gas ◽  
Working Pressure ◽  
Tube Heat Exchanger ◽  
Shell And Tube

High temperature diesel engine exhaust gas can be an important source of heat to operate a bottoming Rankine cycle to produce additional power. In this research, an experiment was performed to calculate the available energy in the exhaust gas of an automotive diesel engine. A shell and tube heat exchanger was used to extract heat from the exhaust gas, and the performance of two shell and tube heat exchangers was investigated with parallel flow arrangement using water as the working fluid. The heat exchangers were purchased from the market. As the design of these heat exchangers was not optimal, the effectiveness was found to be 0.52, which is much lower than the ideal one for this type of application. Therefore, with the available experimental data, the important geometric aspects of the heat exchanger, such as the number and diameter of the tubes and the length and diameter of the shell, were optimized using computational fluid dynamics (CFD) simulation. The optimized heat exchanger effectiveness was found to be 0.74. Using the optimized heat exchangers, simulation was conducted to estimate the possible additional power generation considering 70% isentropic turbine efficiency. The proposed optimized heat exchanger was able to generate 20.6% additional power, which resulted in improvement of overall efficiency from 30% to 39%. Upon investigation of the effect of the working pressure on additional power generation, it was found that higher additional power can be achieved at higher working pressure. For this particular application, 30 bar was found to be the optimum working pressure at rated load. The working pressure was also optimized at part load and found that 2 and 20 were the optimized working pressures for 25% and 83% load. As a result 1.8% and 13.3% additional power were developed, respectively. Thus, waste heat recovery technology has a great potential for saving energy, improving overall engine efficiency, and reducing toxic emission per kilowatt of power generation.

scholarly journals Experimental Investigation and Comparison of Shell Tube and Plate Heat Exchanger used in Water Chillers

2021 ◽  
Vol 23 (1) ◽  
Author(s):  
Shamkuwar S.C ◽  
◽  
Nitin Chopra ◽  
Mihir Kulkarni ◽  
Nikhil Ahire ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Plate Heat Exchanger ◽  
Working Fluid ◽  
Plate Heat ◽  
Tube Heat Exchanger ◽  
Overall Heat Transfer Coefficient ◽  
Shell And Tube

The main objective of the paper is to compare the performance of Shell and tube heat exchanger (STHE) and Plate heat exchanger (PHE) used in chillers. The paper deals with experimental investigation and comparison, which is based on actual testing of STHE and PHE. Both heat exchangers were designed and tested for a heat load of 6000 kcal/hr. In both types of heat exchangers, the primary working fluid used is Refrigerant R22 and secondary working fluid used is water. Theoretical analysis shows that PHE has a 9.67 % less heat transfer area than STHE. Experimental results show that overall heat transfer coefficient (OHTC) for PHE is higher than STHE by 30.96%. The paper also includes a comparison of the heat transfer rate (Q) of the two heat exchangers experimentally.

Investigation of Supercritical CO2 Thermal Hydraulic Characteristics in a Printed Circuit Heat Exchanger

2018 ◽  
Author(s):  
Wen Fu ◽  
Xizhen Ma ◽  
Peiyue Li ◽  
Minghui Zhang ◽  
Sheng Li
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Supercritical Co2 ◽  
Three Dimensional ◽  
Working Fluid ◽  
Printed Circuit ◽  
Carbon Dioxide Co2

Printed circuit heat exchangers are considered for use as the intermediate heat exchangers (IHXs) in high temperature gas-cooled reactors (HTGRs), molten salts reactors (MSRs) and other advanced reactors. A printed circuit heat exchanger (PCHE) is a highly integrated plate-type compact heat exchanger with high-temperature, high-pressure applications and high compactness. A PCHE is built based on the technology of chemical etching and diffusion bonding. A PCHE with supercritical carbon dioxide (CO2) as the working fluid was designed in this study based on the theory correlations. Three-dimensional numerical analysis was then conducted to investigate the heat transfer and pressure drop characteristics of supercritical CO2 in the designed printed circuit heat exchanger using commercial CFD code, FLUENT. The distributions of temperature and velocity through the channel were modeled. The influences of Reynolds number on heat transfer and pressure drop were analyzed. The numerical results agree well with the theory calculations.

Effect of Heat Exchanger Orientations to Recover Heat From the Exhaust of a Diesel Generator Using Rankine Cycle (RC)

2015 ◽  
Author(s):  
S. Bari ◽  
Shekh N. Hossain
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Diesel Generator ◽  
Working Pressure ◽  
Exhaust Heat ◽  
Parallel Arrangement ◽  
Shell And Tube ◽  
Geometric Variables

The heat from the exhaust gas of diesel engines can be an important heat source to provide additional power and improve overall engine efficiency. Studies related to the applications of recoverable heat to produce additional power using separate Rankine cycle are scare. To recover heat from the exhaust of an engine, an efficient heat exchanger is necessary. For this type of application, the heat exchangers are needed to be designed in such a way that it can handle the heat load with reasonable size, weight and pressure drop. In this project, experiments were conducted to measure the exhaust heat available from a 40 kW diesel generator at different loads. Shell and tube heat exchangers were purchased and installed into the engine. The performance of the heat exchangers using water as the working fluid was then conducted. With the available data, computer simulation was carried out using CFD software CFX to improve the design of the heat exchangers. Geometric variables including length, number and diameter of tubes, and baffle design were all tested separately. Upon investigating how these parameters influenced the heat exchangers’ effectiveness, optimum design of shell and tube heat exchangers was proposed. The proposed heat exchangers were manufactured and experiment was conducted. Two heat exchangers were used to generate superheated steam. These two heat exchangers were arranged in two orientations namely, series and parallel. The proposed heat exchanger was able to produce 2.71 kW additional power using water as the working fluid at an optimum working pressure of 15 bar using parallel arrangement. It was found that parallel arrangement generated 10% more additional power than the series arrangement.

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