Optimization of a Primary Heat Exchanger for FLiBe Molten Salt Nuclear Reactor With sCO2 Power System

2021 ◽  
Author(s):  
Emmanuel Gabriel-Ohanu ◽  
Akshay Khadse ◽  
Ladislav Vesely ◽  
Nandhini Raju ◽  
Marcel Otto ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Molten Salt ◽  
Nuclear Reactor ◽  
Inlet Temperature ◽  
Optimized Design ◽  
Reactor Unit ◽  
Power Cycles ◽  
Power Cycle ◽  
Historic Development

Abstract One of the concepts being investigated for Generation IV nuclear reactors is the Molten Salt Reactor (MSR), with designs utilizing molten salts as both fuels and/or coolants. Historic development focused on large reactors, but contemporary efforts are likely to be small and modular, with this analysis considering 30 MWth per reactor unit For both cases, the use of a supercritical carbon dioxide (sCO2) Brayton cycle is being considered for power conversion. Compatibility of sCO2 power cycles with high turbine inlet temperature among several other advantages allows for several nuclear applications. This paper sought to optimize heat exchange between an MSR heat source and an sCO2 power cycle by thermalhydraulically optimizing a salt-heat exchanger sCO2 (HEX). This is accomplished using a one dimensional (1D) heat transfer code that solves for the geometry of a single pass shell-and-tube HEX, as well as pressure loss. Input to the HEX code are derived from a MSR technology assessment and from an optimized recuperated recompression (RRC) sCO2 power cycle. The HEX designs comprise of single shell and tubes with molten salt 2LiFBeF2 (FLiBe) flowing in the shell and sCO2 in the tubes. Hastelloy N is chosen for HEX material due to its tested compatibility with in nuclear application with FLiBe. Shell diameter and number of tubes are varied to optimize length of the HEX. Initial estimate for the weight of the HEX is then compared against the heat transfer area to further converge on an optimized design.

scholarly journals Numerical investigation on thermal performance and flow characteristics of Z and S shape printed circuit heat exchanger using S-CO2

2019 ◽  
Vol 23 (Suppl. 3) ◽  
pp. 757-764
Author(s):  
Yuan-Sheng Lin ◽  
Qi Jing ◽  
Yong-Hui Xie
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Thermal Performance ◽  
Nuclear Reactor ◽  
High Efficiency ◽  
Flow Characteristics ◽  
Energy Industry ◽  
Bend Angle ◽  
Inlet Temperature ◽  
Printed Circuit

As a high-efficiency compact heat exchanger, the printed circuit heat exchanger has been widely applied into nuclear reactor and energy industry. In the present paper, the thermal hydraulic performance of printed circuit heat exchanger based on S-CO2 Brayton power cycle has been numerically investigated for various channel shape and bend angle. A total of seven different shaped channels including straight, Z-10, Z-20, Z-30, S-10, S-20, S-30 are modeled, and evaluated according to the heat transfer and friction performances within the Reynolds number of 5000-30000. The inlet temperature/outlet pressure of hot channel and cold channel are 553 K/2.6 MPa and 381 K/8.5 MPa, respectively. The flow patterns, average Nusselt number, friction factor, and heat exchanger effectiveness are obtained. On the comprehensive consideration of heat transfer enhancement and friction, the S-20 channel produces the best thermal performance. This investigation has provided important reference data for the design of advanced printed circuit heat exchanger in the energy industry.

Temperature Transients in a Triple Heat Exchanger

1984 ◽  
Vol 198 (3) ◽  
pp. 145-154
Author(s):  
P C Chiu ◽  
E H K Fung
Keyword(s):  
Heat Exchanger ◽  
Nuclear Reactor ◽  
Reactor Power ◽  
Solar Heating ◽  
Inlet Temperature ◽  
Exchange Processes ◽  
Flow Experiments ◽  
Heating Plant ◽  
Reactor Power Plant ◽  
Secondary Fluid

A triple heat exchanger, so called because there are three heat exchange processes taking place in it, was built to simulate the system behaviour of a nuclear reactor power plant or a solar heating plant which is characterized by the two circulating loops of the fluid flow. Experiments were carried out to study the temperature transients under disturbances in secondary fluid inlet temperature and power output from immersion heaters. Numerical results were obtained from the weighted residual formulation of the proposed dynamic model and they were shown to be in general agreement with the two sets of experimental responses.

scholarly journals Thermal Analysis of the Effects of Multifaceted Conditions on Performance of Shell-and-Tube Heat Exchanger

2021 ◽  
Vol 6 (1) ◽  
pp. 69-75
Author(s):  
Taiwo O. Oni ◽  
Ayotunde A. Ojo ◽  
Daniel C. Uguru-Okorie ◽  
David O. Akindele
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Parallel Flow ◽  
Hot Water ◽  
Inlet Temperature ◽  
Fiber Glass ◽  
Counter Flow ◽  
Tube Heat Exchanger ◽  
Shell And Tube ◽  
Flow Configurations

A shell-and-tube heat exchanger which was subjected to different flow configurations, viz. counter flow, and parallel flow, was investigated. Each of the flow configurations was operated under two different conditions of the shell, that is, an uninsulated shell and a shell insulated with fiber glass. The hot water inlet temperature of the tube was reduced gradually from 60 oC to 40 oC, and performance evaluation of the heat exchanger was carried out. It was found that for the uninsulated shell, the heat transfer effectiveness for hot water inlet temperature of 60, 55, 50, 45, and 40 oC are 0.243, 0.244, 0.240, 0.240, and 0.247, respectively, for the parallel flow arrangement. For the counter flow arrangement, the heat transfer effectiveness for the uninsulated shell are 2.40, 2.74, 5.00, 4.17, and 2.70%, respectively, higher than those for the parallel flow. The heat exchanger’s heat transfer effectiveness with fiber-glass-insulated shell for the parallel flow condition with tube hot water inlet temperatures of 60, 55, 50, 45, and 40 oC are 0.223, 0.226, 0.220, 0.225, and 0.227, respectively, whereas the counter flow condition has its heat transfer effectiveness increased by 1.28, 1.47, 1.82, 1.11, and 1.18%, respectively, over those of the parallel flow.

scholarly journals Heat Transfer between Molten Salt and Supercritical CO2 in Discontinuous Fins Print Circuits Heat Exchanger

2019 ◽  
Vol 158 ◽  
pp. 5832-5837 ◽  
Author(s):  
Jiewei Lao ◽  
Jing Ding ◽  
Qianmei Fu ◽  
Weilong Wang ◽  
Jianfeng Lu
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Molten Salt ◽  
Supercritical Co2

Fluidized-Bed Heat Transfer Modeling for the Development of Particle/Supercritical-CO2 Heat Exchanger

2017 ◽  
Author(s):  
Zhiwen Ma ◽  
Janna Martinek
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Heat Exchanger ◽  
Fluidized Bed ◽  
Solid Particles ◽  
Heat Transfer Modeling ◽  
Power Cycle ◽  
Heat Exchanger Design ◽  
Temperature Heat ◽  
The Cost

Concentrating solar power (CSP) technology is moving toward high-temperature and high-performance design. One technology approach is to explore high-temperature heat-transfer fluids and storage, integrated with a high-efficiency power cycle such as the supercritical carbon dioxide (s-CO2) Brayton power cycle. The s-CO2 Brayton power system has great potential to enable the future CSP system to achieve high solar-to-electricity conversion efficiency and to reduce the cost of power generation. Solid particles have been proposed as a possible high-temperature heat-transfer medium that is inexpensive and stable at high temperatures above 1,000°C. The particle/heat exchanger provides a connection between the particles and s-CO2 fluid in the emerging s-CO2 power cycles in order to meet CSP power-cycle performance targets of 50% thermal-to-electric efficiency, and dry cooling at an ambient temperature of 40°C. The development goals for a particle/s-CO2 heat exchanger are to heat s-CO2 to ≥720°C and to use direct thermal storage with low-cost, stable solid particles. This paper presents heat-transfer modeling to inform the particle/s-CO2 heat-exchanger design and assess design tradeoffs. The heat-transfer process was modeled based on a particle/s-CO2 counterflow configuration. Empirical heat-transfer correlations for the fluidized bed and s-CO2 were used in calculating the heat-transfer area and optimizing the tube layout. A 2-D computational fluid-dynamics simulation was applied for particle distribution and fluidization characterization. The operating conditions were studied from the heat-transfer analysis, and cost was estimated from the sizing of the heat exchanger. The paper shows the path in achieving the cost and performance objectives for a heat-exchanger design.

System Design of a 2.0 MWth Sodium/Molten Salt Pilot System

2020 ◽  
Author(s):  
Kenneth M. Armijo ◽  
Matthew D. Carlson ◽  
Dwight S. Dorsey ◽  
Joshua M. Christian ◽  
Craig S. Turchi
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
System Design ◽  
Molten Salt ◽  
High Efficiency ◽  
Performance Model ◽  
Transfer Coefficients ◽  
Storage Duration ◽  
Pump Speed ◽  
Receiver System

Abstract Nitrate molten salt concentrating solar power (CSP) systems are currently deployed globally and are considered state-of the art heat transfer fluids (HTFs) for present day high-temperature operation. Although slightly higher limits may be possible with molten salt, to fully realize SunShot efficiency goals of $15/kWhth HTFs and an LCOE of 6¢/kWh, HTF technologies working at higher temperatures (e.g., 650 °C to 750 °C) will require an alternative to molten salts, such as with alkali metal systems. This investigation explores the development of a 2.0 MWth sodium receiver system that employs a sodium receiver as the HTF, as well as with a ternary chloride (20%NaCl/40%MgCl/40%KCl by mol wt.%) salt as a thermal energy storage (TES) medium to facilitate a 6-hr. storage duration. A sodium-to-salt heat exchanger model as well as a salt-to-sCO2 primary heat exchanger model are employed and evaluated in this investigation. A thermodynamic system design model was developed using Engineering Equation Solver (EES) where state properties were calculated at inlets and outlets along both hot and cold legs of the pilot-scale plant. This investigation assesses receiver performance as well as system efficiency studies for the pump and system operational ranges. Results found that high efficiency sodium receivers were found to have higher heat transfer coefficients and required far less spreading of incident flux. The system performance model results suggest that for a pump speed of 2400 RPM, respective hot and cold pump TDH values were determined to be 260.1–307 ft. and 260.1–307 ft for pump flow rates of 90–120 GPM.

Experimental Investigation of Single-Phase Cooling in Embedded Microchannels: 3D Manifold Heat Exchanger With R-245fa

2019 ◽  
Author(s):  
Ki Wook Jung ◽  
Hyoungsoon Lee ◽  
Chirag Kharangate ◽  
Feng Zhou ◽  
Mehdi Asheghi ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Single Phase ◽  
Heat Fluxes ◽  
Experimental Results ◽  
Maximum Temperature ◽  
Inlet Temperature ◽  
Fluid Temperature ◽  
Ir Camera

Abstract High performance and economically viable thermal cooling solutions must be developed to reduce weight and volume, allowing for a wide-spread utilization of hybrid electric vehicles. The traditional embedded microchannel cooling heat sinks suffer from high pressure drop due to small channel dimensions and long flow paths in 2D-plane. Utilizing direct “embedded cooling” strategy in combination with top access 3D-manifold strategy reduces the pressure drop by nearly an order of magnitude. In addition, it provides more temperature uniformity across large area chips and it is less prone to flow instability in two-phase boiling heat transfer. Here, we present the experimental results for single-phase thermofluidic performance of an embedded silicon microchannel cold-plate bonded to a 3D manifold for heat fluxes up to 300 W/cm2 using single-phase R-245fa. The heat exchanger consists of a 52 mm2 heated area with 25 parallel 75 × 150 μm2 microchannels, where the fluid is distributed by a 3D-manifold with 4 micro-conduits of 700 × 250 μm2. Heat is applied to the silicon heat sink using electrical Joule-heating in a metal serpentine bridge and the heated surface temperature is monitored in real-time by Infra-red (IR) camera and electrical resistance thermometry. The experimental results for maximum and average temperatures of the chip, pressure drop, thermal resistance, average heat transfer coefficient for flow rates of 0.1, 0.2. 0.3 and 0.37 lit/min and heat fluxes from 25 to 300 W/cm2 are reported. The proposed Embedded Microchannels-3D Manifold Cooler, or EMMC, device is capable of removing 300 W/cm2 at maximum temperature 80 °C with pressure drop of less than 30 kPa, where the flow rate, inlet temperature and pressures are 0.37 lit/min, 25 °C and 350 kPa, respectively. The experimental uncertainties of the test results are estimated, and the uncertainties are the highest for heat fluxes < 50 W/cm2 due to difficulty in precisely measuring the fluid temperature at the inlet and outlet of the micro-cooler.

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