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NASA NTRS2014

Overview of the 6 Meter HIAD Inflatable Structure and Flexible TPS Static Load Test Series

To support NASAs long term goal of landing humans on Mars, technologies which enable the landing of heavy payloads are being developed. Current entry, decent, and landing technologies are not practical for this class of payloads due to geometric constraints dictated by current launch vehicle fairing limitations. Therefore, past and present technologies are now being explored to provide a mass and volume efficient solution to atmospheric entry, including Hypersonic Inflatable Aerodynamic Decelerators (HIADs). At the beginning of 2014, a 6m HIAD inflatable structure with an integrated flexible thermal protection system (TPS) was subjected to a static load test series to verify the designs structural performance. The 6m HIAD structure was constructed in a stacked toroid configuration using nine inflatable torus segments composed of fiber reinforced thin films, which were joined together using adhesives and high strength textile woven structural straps to help distribute the loads throughout the inflatable structure. The 6m flexible TPS was constructed using multiple layers of high performance materials to protect the inflatable structure from heat loads that would be seen during atmospheric entry. To perform the static load test series, a custom test fixture was constructed. The fixture consisted of a structural tub rim with enough height to allow for displacement of the inflatable structure as loads were applied. The bottom of the tub rim had an airtight seal with the floor. The centerbody of the inflatable structure was attached to a pedestal mount as seen in Figure 1. Using an impermeable membrane seal draped over the test article, partial vacuum was pulled beneath the HIAD, resulting in a uniform static pressure load applied to the outer surface. During the test series an extensive amount of instrumentation was used to provide many data sets including: deformed shape, shoulder deflection, strap loads, cord loads, inflation pressures, and applied static load.In this overview, the 6m HIAD static load test series will be discussed in detail, including the 6m HIAD inflatable structure and flexible TPS design, test setup and execution, and finally initial results and conclusions from the test series.

inflatable aerodynamic decelerator↗

NASA NTRS2017

Mars Propellant Liquefaction and Storage Performance Modeling using Thermal Desktop with an Integrated Cryocooler Model

NASAs current Mars architectures are assuming the production and storage of 23 tons of liquid oxygen on the surface of Mars over a duration of 500+ days. In order to do this in a mass efficient manner, an energy efficient refrigeration system will be required. Based on previous analysis NASA has decided to do all liquefaction in the propulsion vehicle storage tanks. In order to allow for transient Martian environmental effects, a propellant liquefaction and storage system for a Mars Ascent Vehicle (MAV) was modeled using Thermal Desktop. The model consisted of a propellant tank containing a broad area cooling loop heat exchanger integrated with a reverse turbo Brayton cryocooler. Cryocooler sizing and performance modeling was conducted using MAV diurnal heat loads and radiator rejection temperatures predicted from a previous thermal model of the MAV. A system was also sized and modeled using an alternative heat rejection system that relies on a forced convection heat exchanger. Cryocooler mass, input power, and heat rejection for both systems were estimated and compared against sizing based on non-transient sizing estimates.

fluid modeling↗

NASA NTRS2017

Mars Propellant Liquefaction Modeling in Thermal Desktop

Cryogenics↗

NASA NTRS2014

Overview of the 6m HIAD Inflatable Structure and Flexible TPS Static Load Test Series

To support NASAs long term goal of landing humans on Mars, technologies which enable the landing of heavy payloads are being developed. Current entry, decent, and landing technologies are not practical for this class of payloads due to geometric constraints dictated by current launch vehicle fairing limitations. Therefore, past and present technologies are now being explored to provide a mass and volume efficient solution to atmospheric entry, including Hypersonic Inflatable Aerodynamic Decelerators (HIADs). At the beginning of 2014, a 6m HIAD inflatable structure with an integrated flexible thermal protection system (TPS) was subjected to a static load test series to verify the designs structural performace. The 6m HIAD structure was constructed in a stacked toroid configuration using nine inflatable torus segments composed of fiber reinforced thin films, which were joined together using adhesives and high strength textile woven structural straps to help distribute the loads throughout the inflatable structure. The 6m flexible TPS was constructed using multiple layers of high performance materials to protect the inflatable structure from heat loads that would be seen during atmospheric entry. To perform the static load test series, a custom test fixture was constructed. The fixture consisted of a structural tub rim with enough height to allow for displacement of the inflatable structure as loads were applied. The bottom of the tub rim had an airtight seal with the floor. The centerbody of the inflatable structure was attached to a pedestal mount as seen in Figure 1. Using an impermeable membrane seal draped over the test article, partial vacuum was pulled beneath the HIAD, resulting in a uniform static pressure load applied to the outer surface. During the test series an extensive amount of instrumentation was used to provide many data sets including: deformed shape, shoulder deflection, strap loads, cord loads, inflation pressures, and applied static load.In this overview, the 6m HIAD static load test series will be discussed in detail, including the 6m HIAD inflatable structure and flexible TPS design, test setup and execution, and finally initial results and conclusions from the test series.

TPS↗

DOE OSTI2016

Building America Case Study: Mockup Small-Diameter Air Distribution System

This report investigates the feasibility of using a home-run manifold small-diameter duct system to provide space conditioning air to individual thermal zones in a low-load home. This compact layout allows duct systems to be brought easily within conditioned space via interior partition walls. Centrally locating the air hander unit in the house significantly reduces duct lengths. The plenum box is designed so that each connected duct receives an equal amount of airflow, regardless of the duct position on the box. Furthermore, within a reasonable set of length restrictions, each duct continues to receive similar airflow. The design method uses an additive approach to reach the total needed zonal airflow. Once the cubic feet per minute needed to satisfy the thermal load of a zone has been determined, the total number of duct runs to a zone can be calculated by dividing the required airflow by the standard airflow from each duct. The additive approach greatly simplifies the design effort and reduces the potential for duct design mistakes to be made. Measured results indicate that this plenum design can satisfy the heating load. However, the total airflow falls short of satisfying the cooling load in a hypothetical building. Static pressure inside the plenum box of 51.5 Pa limited the total airflow of the attached mini-split heat pump blower, thus limiting the total thermal capacity. Fan energy consumption is kept to 0.16 to 0.22 watt/CFM by using short duct runs and smooth duct material.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2016

Performance Analysis of a Modular Small-Diamter Air Distribution System

This report investigates the feasibility of using a home-run manifold small-diameter duct system to provide space conditioning air to individual thermal zones in a low-load home. This compact layout allows duct systems to be brought easily within conditioned space via interior partition walls. Centrally locating the air handler unit in the house significantly reduces duct lengths. The plenum box is designed so that each connected duct receives an equal amount of airflow, regardless of the duct position on the box. Furthermore, within a reasonable set of length restrictions, each duct continues to receive similar airflow. The design method uses an additive approach to reach the total needed zonal airflow. Once the cubic feet per minute needed to satisfy the thermal load of a zone has been determined, the total number of duct runs to a zone can be calculated by dividing the required airflow by the standard airflow from each duct. The additive approach greatly simplifies the design effort and reduces the potential for duct design mistakes to be made. Measured results indicate that this plenum design can satisfy the heating load. However, the total airflow falls short of satisfying the cooling load in a hypothetical building. Static pressure inside the plenum box of 51.5 Pa limited the total airflow of the attached mini-split heat pump blower, thus limiting the total thermal capacity. Fan energy consumption is kept to 0.16 to 0.22 watt/CFM by using short duct runs and smooth duct material.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2017

A Proposed Path Forward for Standardization - 17131

Incorporation of a standardized canister system into the commercial waste management system represents an opportunity to develop an integrated approach to storage, transportation, and disposal issues. However, regardless of timing and method, deployment of such a system would have the potential to cause significant system-wide impacts. The current inventory of commercial spent nuclear fuel dry storage systems is diverse and increasing. In addition, the currently loaded systems are large-capacity systems (up to 37 pressurized water reactor assemblies or 89 boiling water reactor assemblies) that are now able to accommodate large (greater than 45 kilowatts) amounts of heat during storage, with the potential to accommodate fairly high heat loads (∼32 kilowatts) for transportation as well. A standardized canister system designed with disposition in mind would likely be significantly smaller than the current systems and have dramatically lower heat limit maximums. Over the past few years, the Department of Energy (DOE) Office of Nuclear Energy Fuel Cycle Technologies Nuclear Fuels Storage and Transportation Planning Project (NFST) has performed a number of system analyses using logistic simulations to evaluate the impacts of incorporating these smaller canisters into the commercial waste management system. These simulations predict the amount of resources (e.g., staff, canisters/casks, rail-cars, facilities), the size of facilities, and the timing of operations, as well as provide rough order-of-magnitude cost estimates. In addition to system analyses, DOE funded efforts by EnergySolutions to develop a generic design of a small-capacity standardized canister system and investigate innovative operational approaches to minimize the at-reactor operational impacts of loading such smaller canisters. A result of EnergySolutions' work was the development of a 'canister-in-carrier' concept that would allow for loading, storing, transporting, and potentially disposing of groups of small canisters at the same time. With the inclusion of this new concept, the most recent system analyses show that incorporating standardized canister systems into the commercial waste management system has the potential for some system-wide cost reductions in addition to the flexibility that smaller canisters would provide to the system. Based on these analyses, the authors of this paper recommend that DOE fund (1) a demonstration of the ability to weld up to four small canisters at the same time to confirm the feasibility and practicality of the canister-in-carrier concept and (2) the development of a more detailed conceptual design for future applications for Certificates of Compliance, if standardized canisters were incorporated into the commercial waste management system. This paper documents both the results of the latest assessment of standardized canister concepts including the canister-in-carrier concept and the authors' recommendations. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2021

High flux boiling heat transfer enhancement using triangle shaped vertical walls in two-phase microchannel heat exchangers

Two-phase heat exchangers allow heat loads to be dissipated with lower fluid flow rates without inducing thermal gradients, and high surface area microchannels further reduce the thermal resistance of these heat exchangers. However, there are many practical limits that prevent widespread use of two-phase microchannel heat exchangers. Many authors have looked to address these practical limits by treating the channel floors or creating artificial nucleation sites. Few works look to enhance heat transfer in the walls of channels with hydraulic diameters below 200 μm. This work is aimed at increasing the efficacy of high aspect ratio silicon microchannels that use R134a as the working fluid. The 125 parallel channels are 40 μm wide, 200 μm deep, and 2 mm long and contain a 15 μm wide, 150 μm long restriction at each inlet. The thermal resistance and dryout characteristics of traditional, plain-walled channels are compared to channels with 2 area enhancement patterns each of which increases the area available for heat transfer by 41%. Furthermore, a resistance to dryout is seen in both area-enhanced test sections, and a 15.5% reduction in thermal resistance is shown for the area-enhanced part with a 6 μm triangular pitch. Only a 7.8% performance increase is seen in the test section with a 3 μm pitch. Both area enhancement patterns induce an average 27% increase in pressure drop for all tests. Heat transfer characteristics are solved for using a finite element analysis (FEA) model. By examining heat transfer coefficients and local heat fluxes, it is postulated that the area enhancement reduces heat transfer coefficients and the performance increase is caused by increasing the number of active nucleation sites.

42 ENGINEERING↗

NASA NTRS2019

Vibration-Heating in ADR Kevlar Suspension Systems

The cryogenics group at NASA's Goddard Space Flight Center has a long-standing development and test program for laboratory and space-flight adiabatic demagnetization refrigerators (ADRs). These devices are used to cool components to temperatures as low as 0.05 K. At such low temperatures the ADR systems can provide a few micro-Watts of cooling power, so it is important to minimize the conduction of heat to these cold stages from the surroundings. The cold ADR elements are held in place by thin tensioned strings made of Kevlar, chosen for its high strength and stiffness and low thermal conductivity. During laboratory testing, we have observed that occasional significant additional heat loads on the coldest ADR stages correlate with unusually high vibration levels in the cryostat due to a noisy mechanical cryocooler. We theorized that this heat results from plastic deformation of the Kevlar fibers and frictional interactions among them, driven by the cryostat vibrations. We describe tests and calculations performed in attempt to confirm this source of the heating, and we discuss possible strategies to reduce this effect in future ADR suspension systems.

Vibration-heating↗

DOE OSTI2016

Optimizing the CSP Tower Air Brayton Cycle System to Meet the SunShot Objectives - Final Technical Report

The objective of this project is to increase Concentrated Solar Power (CSP) tower air receiver and gas turbine temperature capabilities to 1,000ºC by the development of a novel gas turbine combustor, which can be integrated on a megawatt-scale gas turbine, such as the Solar Turbines Mercury 50™. No combustor technology currently available is compatible with the CSP application target inlet air temperature of 1,000°C. Autoignition and flashback at this temperature prevent the use of conventional lean pre-mix injectors that are currently employed to manage NOx emissions. Additional challenges are introduced by the variability of the high-temperature heat source provided by the field of solar collectors, the heliostat in CSP plants. For optimum energy generation from the power turbine, the turbine rotor inlet temperature (TRIT) should remain constant. As a result of changing heat load provided to the solar collector from the heliostat, the amount of energy input required from the combustion system must be adjusted to compensate. A novel multi-bank lean micro-mix injector has been designed and built to address the challenges of high-temperature combustion found in CSP applications. The multi-bank arrangement of the micro-mix injector selectively injects fuel to meet the heat addition requirements to maintain constant TRIT with changing solar load. To validate the design, operation, and performance of the multi-bank lean micro-mix injector, a novel combustion test facility has been designed and built at Southwest Research Institute® (SwRI®) in San Antonio, TX. This facility, located in the Turbomachinery Research Facility, provides in excess of two kilograms per second of compressed air at nearly eight bar pressure. A two-megawatt electric heater raises the inlet temperature to 800°C while a secondary gas-fired heater extends the operational temperature range of the facility to 1,000°C. A combustor test rig connected to the heater has been designed and built to test the multi-bank lean micro-mix injector over the range of CSP operating conditions. The fuel is controlled and selectively delivered to the banks of the injector based on combustor inlet conditions that correspond to turbine operating points. The combustor rig is equipped with a data acquisition system and a suite of instrumentation for measuring temperature, pressure, and species concentration. This unique test facility has been built and commissioned and a prototype of the multi-bank lean micro-mix injector design has been tested. Operation of the combustor and injector has been demonstrated over the full range of CSP inlet conditions and for the range of turbine load conditions specified. The multi-bank operation of the injector has been proven to be an effective design for managing the variable flow rates of air and fuel due to changing inlet conditions from the solar field and turbine loads.

14 SOLAR ENERGY↗

NASA NTRS2012

Reusable Solid Rocket Motor - V(RSRMV)Nozzle Forward Nose Ring Thermo-Structural Modeling

During the developmental static fire program for NASAs Reusable Solid Rocket Motor-V (RSRMV), an anomalous erosion condition appeared on the nozzle Carbon Cloth Phenolic nose ring that had not been observed in the space shuttle RSRM program. There were regions of augmented erosion located on the bottom of the forward nose ring (FNR) that measured nine tenths of an inch deeper than the surrounding material. Estimates of heating conditions for the RSRMV nozzle based on limited char and erosion data indicate that the total heat loading into the FNR, for the new five segment motor, is about 40-50% higher than the baseline shuttle RSRM nozzle FNR. Fault tree analysis of the augmented erosion condition has lead to a focus on a thermomechanical response of the material that is outside the existing experience base of shuttle CCP materials for this application. This paper provides a sensitivity study of the CCP material thermo-structural response subject to the design constraints and heating conditions unique to the RSRMV Forward Nose Ring application. Modeling techniques are based on 1-D thermal and porous media calculations where in-depth interlaminar loading conditions are calculated and compared to known capabilities at elevated temperatures. Parameters such as heat rate, in-depth pressures and temperature, degree of char, associated with initiation of the mechanical removal process are quantified and compared to a baseline thermo-chemical material removal mode. Conclusions regarding postulated material loss mechanisms are offered.

Clayton, J. Louie↗

NASA NTRS1984

Integration and flight demonstration of a high-capacity monogroove heat-pipe radiator

The cancellation of the TDRS-B satellite as the payload for the eighth Space Shuttle mission provided a unique opportunity to demonstrate on-orbit operation of the high-capacity monogroove heat pipe used in the space constructible radiator subsystem. In less than 4 months, a flight experiment was conceived, designed, fabricated, tested, integrated with a payload carrier, installed in the Orbiter Challenger payload bay, and successfully operated in flight. Still color photographs and direct crew visual observation of color changes in a pattern of temperature-sensitive liquid-crystal tapes provided the temperature data necessary to verify successful on-orbit startup and orbital transient response of the heat pipe when subjected to a heat load from its attached electrical heaters. This successful on-orbit demonstration verified analytical design tools and provided confidence in the use of high-capacity heat pipes for future space applications. The flight experiment hardware and the integration and test activities that led to the flight are described, and the actual flight results are compared to analytical performance predictions.

Rankin, J. G.↗

NASA NTRS1989

Testing of a controller for a hybrid capillary pumped loop thermal control system

A controller for a series hybrid capillary pumped loop (CPL) system that requires no moving parts does not resrict fluid flow has been tested and has demonstrated improved performance characteristics over a plain CPL system and simple hybrid CPL systems. These include heat load sharing, phase separation, self-regulated flow control and distribution, all independent of most system pressure drop. In addition, the controlled system demonstrated a greater heat transport capability than the simple CPL system but without the large fluid inventory requirement of the hybrid systems. A description of the testing is presented along with data that show the advantages of the system.

Schweickart, Russell↗

NASA NTRS1991

Investigation of thermal-fluid mechanical characteristics of the Capillary Pump Loop

The main purpose is the experimental and analytical study of behavior of the Capillary Pump Loop (CPL) heat pipe system during the transient mode of operating by applying a step heat pulse to one or more evaporators. Prediction of the CPL behavior when subjected to pulse heat loading requires further study before the transient response of CPL system can be fully understood. The following tasks are discussed: (1) exploratory testing of a CPL heat pipe for transient operational conditions which could generate the type of oscillatory inlet temperature behavior observed in an earlier testing of NASA/GSFC CPL-2 heat pipe system; (2) analytical investigation of the CPL inlet section temperature oscillations; (3) design, construction and testing of a bench-top CPL test system for study of the CPL transient operation; and (4) transient analysis of a CPL heat pipe by applying a step power input to the evaporators.

Kiper, Ali M.↗

NASA NTRSDate not supplied

Magnetohydrodynamics (MHD) Aerocapture System for Enabling Faster-Larger Planetary Science & Human Exploration Missions

Since our completing the NIAC Phase I NIAC on this Advanced Aerocapture System, NASA Langley Research Center has funded or supported a number of studies and code enhancements through its Center Innovation Fund (CIF) and NASA’s NSTGRO and Internship Programs to mature the analysis capabilities and quantify the merits of the MHD Aerocapture System technology. These efforts have resulted in a plug and play analysis capability for assessing MHD aerocapture system performance for arrival at many planetary bodies of interest. Our efforts have especially focused on the potential mass savings for improving the capacity for science observations at Neptune and Triton. A re-cent Forbes article published “‘Orbital mechanics is probably going to decide for us whether we go to Uranus or Neptune because we need to flyby Jupiter,’ said Kunio Sayanagi at Hampton University, Virginia, who also worked on the Neptune Odyssey proposal…. Exactly when a mission can be sent to Uranus, or Neptune, depends on the relative position of Jupiter, which can help give a spacecraft a gravitational slingshot. That drastically shortens the cruise phase.” [1] Since shortening the cruise phase is important for these science missions, any mass savings enabled by the MHD Aerocapture System could be reallocated to increasing Thermal Protection System mass to allow faster arrival speeds and/or for onboarding additional payloads such as science instruments, batteries, or propellant for conducting more science for longer durations in the desired orbits. The analysis steps and codes for conducting trades and sizing vehicles for aerocapture are as follows: Step 1 is to conduct aeroheating analysis using LAURA of the selected entry vehicle shape to identify locations on the forebody where ionization and flow velocity are sufficient for producing Lo-rentz forces. LAURA is a multiblock structured grid finite-volume CFD solver developed at the NASA Langley Research Center. [2] LAURA has been used for aerothermal analysis support of the entry, de-scent and landing (EDL) phase of interplanetary missions over the last three decades [3-7]. Step 2 is to port the LAURA results into CFDWARP to calcu-late electrical and thermal conductivities of ionized flow for sizing MHD patch system and calculating Lorentz forces needed for controls analysis. CFDWARP is a CFD code that uses advanced nu-merical methods that enable the simulation of the full coupling between the aerodynamics, the magne-tohydrodynamics, and the non-neutral plasma sheaths. CFDWARP has the unique capability to simulate efficiently the non-neutral sheaths (near the electrodes) in coupled form with the quasi-neutral bulk MHD flow [8-11]. Step 3 is to link re-sults from LAURA and CFDWARP into POST2 for calculating entry trajectories and comparing MHD control results with other aerodynamic control strategies. The Program to Optimize Simulated Tra-jectories II (POST2) is a generalized point mass, discrete parameter targeting and optimization pro-gram. POST2 provides the capability to target and optimize point mass trajectories for multiple pow-ered or un-powered vehicles near an arbitrary rotat-ing, oblate planet [12]. Step 4: TPS sizing was per-formed using the Fully Implicit Ablation and Ther-mal-response code (FIAT) tool which computes the transient one-dimensional thermal response and surface thermochemistry of a multilayer stackup of thermal protection, bonding, and structural materi-als subject to aeroheating on one surface [13]. The sizing and margining methodology used was based on the approach documented by Mahzari and Milos [14] for the dual-layered heatshield for extreme entry environment technology (DL-HEEET) TPS concept. TPS analysis utilizes trajectory information from POST2. Using this step-wise plug and play MHD Aerocapture performance assessment process, our analysis targets a Neptune aerocapture trajectory that will place the spacecraft in an observation orbit for Triton. [15]. Magnetohydrodynamic (MHD) control of a 4.5-meter diameter MSL-style capsule resulted in TPS mass savings of nearly 2000 kg when using an MHD system mass of under 200 kg. The flight path for a vehicle using the MHD control strategy has a much lower heat rate and heat load compared to the conventional aerodynamic aerocapture strategies known as bank angle con-trolled (BAC) and direct force controlled (DFC). Both BAC and DFC have heat rates significantly greater than 1500 W/cm2 typically used as an upper limit for PICA. Thus, DL-HEEET TPS concept was required for the BAC and DFC control strategies. However, considering the more benign environ-ments for the MHD case, additional TPS concepts with improved mass efficiency were also assessed. PICA was considered for the MHD controlled strat-egy since the maximum heat rate was well within the limits (<1500 W/cm2) of PICA. TPS sizing re-sulted in a significant mass reduction. The PICA layer for this sizing case was about 7.8 cm. As a point of reference, the Mars 2020 mission, which used this same PICA concept, had a PICA thickness of 3.18 cm [16]. The trajectories used for the TPS sizing originat-ed from the POST2 simulations. The current, I, to an electromagnet configuration can be manipulated to allow for active control of the vehicle. Manipula-tion of the current, I, changes the magnetic field, B, which affects the Lorentz force and therefore the MHD drag force on the vehicle. Our analysis in-cluded both open-loop and close-loop control. Closed-loop control will enable improved overall performance when taking into account mission level uncertainties, such as interplanetary delivery errors and atmospheric modeling uncertainties. The open-loop and closed-loop MHD control cases do not dip as deep into the atmosphere as the aerodynamic cases. Three types of aerodynamic-only approach-es are investigated: bank angle modulation (BAM), director force control (DFC), and Drag Modulated. BAM and DFC make use of vehicle aerodynamic angles to steer the vehicle. Thus, changing the aer-odynamic forces acting on the vehicle for control, aerodynamic drag modulated case requires a vary-ing drag area to modulate the drag force. The MHD drag modulated case modulates MHD generated drag force that adds to the aerodynamic drag. This higher atmospheric activation of drag forces by the MHD patch results in significantly less heat flux on the vehicle. The MHD technology will enable shorter cruise times and deceleration of larger payloads for increasing the capacity for science at the Ice Giants or for returning astronauts to Earth from cislunar space or from Mars. The purpose of this presentation is to provide more details about this work and to highlight plans for further research and development including a flight demonstration.

R. W. Moses↗

DOE OSTI2023

A novel 3-D pulsating heat pipe module for high heat-flux applications

This study proposed a novel pulsating heat pipes (PHP) for high-flux thermal module. According to the open literature, the maximum value of the heat flux is 23.7 W∙cm –2 handled by PHP, which is far behind industry requirements. Therefore, the present study proposes a novel 3D PHP suitable for high heat-flux applications. The PHP were experimentally tested for different working fluids, including methanol and water. Furthermore, the experiments were performed to analyze the influence of various operating parameters, such as filling ratio (25–60%), heat load (100–800 W), and air flow rate 100–250 cubic feet per minute (CFM). In this work, the results showed that this PHP can sustain a heat flux up to 70 W∙cm –2 with the maximum case temperature under 80 °C, which is approximately three times higher than the available literature. Furthermore, the performance of the PHP module was compared against the commercial module with wicked heat pipe. The PHP exhibited about 7% higher heat dissipation compared to the commercial module. Since the proposed module uses simple copper tubes in its construction over the wicked structure used in commercial module, the novel 3D PHP module provides additional economic and mass production capability.

3D pulsating heat pipe↗

DOE OSTI2017

Thermal Analysis Capability of UNF-ST&DARDS

In the United States, approximately 2,500 casks are loaded with commercial spent nuclear fuel (SNF) that has transitioned from wet storage (spent fuel pools) to dry storage. The number of loaded dry storage casks is increasing by approximately 200 each year. Over time, cask designs have evolved to enhance safety and to accommodate more fuel and higher heat loads. Also, higher burnup fuel is being transitioned into dry storage. The SNF is being stored in dry casks for longer times than specified in the original certification period. Several degradation mechanisms related to fuel assemblies and canisters are affected by temperature. For the cladding, temperature-dependent phenomena include creep and annealing, hydride reorientation and embrittlement, and the ductile-to-brittle transition. Temperature can also influence phenomena that affect the long-term integrity of the storage system, including deliquescence, corrosion, and stress-corrosion cracking. Therefore, accurate determination of the temperatures of various components is needed to evaluate potential safety-related issues during transportation after extended storage and to ensure SNF retrievability. The Used Nuclear Fuel-Storage, Transportation & Disposal Analysis Resource and Data System (UNF ST&DARDS) is being developed for the US Department of Energy Office of Nuclear Energy to streamline analyses for the waste management system [1]. Lastly, the thermal analysis capability within UNF-ST&DARDS and example results are discussed herein.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

NASA NTRS1971

Radiator design system computer programs

Minimum weight space radiator subsystems which can operate over heat load ranges wider than the capabilities of current subsystems are investigated according to projected trends of future long duration space vehicles. Special consideration is given to maximum heat rejection requirements of the low temperature radiators needed for environmental control systems. The set of radiator design programs that have resulted from this investigation are presented in order to provide the analyst with a capability to generate optimum weight radiator panels or sets of panels from practical design considerations, including transient performance. Modifications are also provided for existing programs to improve capability and user convenience.

Wiggins, C. L.↗