Engineering design elements of a two-phase thermosyphon for the purpose of transferring NGNP thermal energy to a hydrogen plant

Sabharwall, Piyush; Gunnerson, F.S.

doi:10.1016/j.nucengdes.2009.06.022

Cited by 35 publications

(20 citation statements)

References 6 publications

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“…The process plant will likely be separated from the nuclear plant because of safety, contamination, and licensing requirements (Sabharwall and Gunnerson 2009). Therefore the heat transfer fluid will likely have to travel significant distances without much, if any, temperature drop as most of the process heat applications are temperature driven.…”

Section: Figure 1-2 Thermal Energy Transfer In Fhr For Power or Procmentioning

confidence: 99%

“…This issue is particularly challenging when considering process heat applications that are separated from the nuclear island because of safety, contamination, and licensing requirements (Sabharwall and Gunnerson 2009), when the heat transfer fluid must travel significant distance within insulated pipes. Effects of salt properties variations with temperature on structural and components materials must also be considered for long term operation and reliability x Instrumentation and inspection techniques for molten salt components require development and validation.…”

Section: Challenges With Molten Saltsmentioning

confidence: 99%

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Process Heat Exchanger Options for Fluoride Salt High Temperature Reactor

Sabharwall¹,

Kim²,

McKellar³

et al. 2011

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The work reported herein is a significant intermediate step in reaching the final goal of commercial-scale deployment and usage of molten salt as the heat transport medium for process heat applications. The primary purpose of this study is to aid in the development and selection of a heat exchanger for power production and/or process heat application, which would support large-scale deployment.vi vii SUMMARYThe strategic goal of the Advanced Reactor Concept Program for the fluoride high temperature reactor (FHR) is to broaden the environmental and economic benefits of nuclear energy in the U.S. economy by producing power to meet growing energy demands and demonstrating the FHRs applicability to market sectors not being served by light water reactors.The primary purpose of this study is to aid in the development and selection of a heat exchanger for power production and/or process heat applications for the Fluoride High Temperature Reactor (FHR), which would support large-scale deployment. Of primary importance is the transfer of heat from the reactor to the power generation and/or process heat application. Heat in the FHR is transferred from the reactor core by the primary liquid-salt coolant to an intermediate heattransfer loop through an intermediate heat exchanger. The intermediate heattransfer loop uses a secondary liquid-salt coolant through a secondary heat exchanger to move the heat to a power conversion system or a process heat industrial application.Three molten salt coolants were considered for use in the secondary coolant loop: LiF-NaF-KF (FLiNaK), KF-ZrF 4 , and KCl-MgCl 2 . The potential power conversion cycles identified are a super-critical Rankine steam cycle, a supercritical CO 2 cycle, a subcritical Rankine steam cycle, and a helium Brayton cycle. Each of these cycles achieves different values of thermal efficiency along with diverse operating conditions. The choice of the heat exchanger type will largely depend on the operating conditions of the power conversion cycle.Potential process heat applications were evaluated considering a maximum available temperature of 650ºC for use by the process heat applications. The current FHR design could provide process heat for the following applications in the near term:x Power production cycles (steam Rankine cycles, helium Brayton cycle, SCO 2 cycle)x Oil shale (in situ)x Oil shale (ex situ)x Oil sands.The characteristics of candidate molten salt coolants were extensively investigated in three different aspects: coolant thermal performance, coolant cost, and coolant chemistry (corrosion). Details of these characteristics, presented in Appendix A, are summarized as follows:x Thermal Performance: Six Figures of merit (FOMs) were developed in this study by an analytical approach to compare the thermal characteristics of various coolants. The FOMs were mathematically derived and the sensitivity of each property on the FOMs was also estimated. Overall, FLiNaK (LiFNaF-KF) showed superior thermal performance compared to the other candidate coolants, alt...

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Section: Figure 1-2 Thermal Energy Transfer In Fhr For Power or Procmentioning

confidence: 99%

Section: Challenges With Molten Saltsmentioning

confidence: 99%

Process Heat Exchanger Options for Fluoride Salt High Temperature Reactor

Sabharwall¹,

Kim²,

McKellar³

et al. 2011

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“…One significant advantage of heat transfer by thermosyphon is the characteristic of nearly isothermal phase change heat transport, which makes the thermosyphon an ideal candidate for applications where the temperature gradient is limited and high delivery temperatures are required, as in the case of thermochemical hydrogen production (Sabharwall and Gunnerson 2009;Sabharwall 2009). The nature of isothermal heat transport results in an extremely high thermal conductance (defined as the heat transfer rate per unit temperature difference).…”

Section: Thermosyphon Designmentioning

confidence: 99%

“…Vapor-phase velocities within a thermosyphon can also be much greater than single-phase liquid velocities within a forced convective loop. Figure 9 exemplifies the enthalpy enhancement in heat transfer afforded by a two-phase thermosyphon versus a single-phase convective loop with sodium as the working fluid as shown by Sabharwall et al 2009. The specific enthalpy (∆h) of saturated liquid and vapor, relative to the solid at 298.15 K, is illustrated as a function of temperature.…”

Section: Comparison Of Thermosyphon With Convective Loopmentioning

confidence: 99%

High Temperature Thermal Devices for Nuclear Process Heat Transfer Applications

Sabharwall¹,

Kim²

2011

Developments in Heat Transfer

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“…The Next Generation Nuclear Plant (NGNP), a high temperature gas-cooled reactor (HTGR) design, is based on providing process heat to a wide range of high temperature processes. NGNP will be able to provide electrical power and process heat to be used in hydrogen production, industrial applications, coal gasification, enhanced oil recovery (Sabharwall, 2009), and several other petro-chemical processes. Safety and reliability are paramount to the success of the NGNP.…”

Section: Introductionmentioning

confidence: 99%