Frequency Of Temperature Fluctuations Research Articles

Large Eddy simulation on the Lead-Bismuth Eutectic jet at reactor core outlet

The Lead-Bismuth Eutectic (LBE) Cooled Fast Reactor (LFR) represents a promising Generation-IV technology, anticipated to offer a sustainable, safe, and clean energy solution. LBE fluid from LFR assemblies varies in temperature, causing violent temperature oscillations during the jet mixing that may contribute to structural fatigue, threatening LFR safety. This study focuses on investigating the critical thermal–hydraulic phenomena occurring at the core outlet of the LFR by modeling the assembly head in a realistic reactor configuration. Large Eddy Simulation (LES) is employed to explore the LBE jet characteristics in a three-head model with varying inlet parameters. The analysis includes the fluctuation patterns of both the flow and temperature fields downstream of the assembly head. The results show that the influence area of the assembly head is mainly in the range of about 0–175 mm downstream of the outlet of the assembly head. The temperature fluctuation frequency is the highest near the assembly head, typically within 20 Hz, and the temperature fluctuation frequency in other areas is lower. These findings provide valuable insights for designing LFRs and understanding the flow and heat transfer behavior of liquid metals.

Model-based prediction of frost formation inside frozen food packages under temperature fluctuations

Abstract Frozen storage of food products is widely accepted not only in the industry but also by households. Frost formation during long-term storage is recognized as a phenomenon that causes changes in product characteristics and quality losses. However, quantitative prediction and control of frost formation remains a challenge. In this study, a mathematical model was developed to predict frost formation inside frozen food products (i.e., frozen minced meat packed in a polyvinylidene chloride (PVDC) film) under fluctuating temperature conditions in a domestic refrigerator. The proposed model is based on heat transfer and energy balance equations, and the amount of frost formation is estimated from the heat generated by condensation. The heat transfer coefficients were experimentally obtained and applied to the developed model. The interactions between the amplitude and frequency of temperature fluctuations and the corresponding amount of frost formation were visualized using contour plots. Both the amplitude and frequency were found to increase frost formation. For the range of fluctuations tested (temperature amplitudes of 0.5–2.5 K and cooling rates of 0.0125–0.2 K/min when connected to the compressor), the simulation predicted that the amount of frost in the packages varied up to approximately 4.5 times (0.48–2.18 g/month for packages containing 300 g of minced meat) depending on the different temperature fluctuation settings.

Effects of temperature and pressure fluctuations on exergy loss characteristics of hydrogen auto-ignition processes

Intake temperature and pressure fluctuations prior to main ignition are one of the reasons affecting the efficiency of internal combustion engines. In this study, the effects of temperature and pressure fluctuations with varied amplitudes and frequencies on the exergy loss of hydrogen auto-ignition processes were numerically investigated in an adiabatic constant-volume system at engine-relevant conditions. The results revealed that the increase in temperature fluctuation amplitudes primarily decreases the exergy loss due to chemical reactions, and the exergy loss due to incomplete combustion remains unchanged. Specifically, the total exergy loss is reduced by approximately 1.5% with a temperature fluctuation amplitude of 100 K at a frequency of 2 ms−1. Furthermore, with the same temperature fluctuation amplitude, increasing the frequency of temperature fluctuation from 2 ms−1 to 7 ms−1 leads to a 0.7% increase in the total exergy loss. On the other hand, the effects of pressure fluctuation on the exergy loss of hydrogen auto-ignition processes are negligible compared with those of temperature fluctuation. Through chemical kinetic analysis, it is found that temperature fluctuation promotes the consumption pathway of O2 to generate OH, rather than the collision with H to produce HO2. Consequently, the reduced mole fraction of HO2 inhibits the related HO2-consumption reactions, including HO2+HOH + OH and HO2+HO2H2O2+O2. Moreover, with temperature fluctuation, due to the lower fraction of third-body collision molecules, H2O, the reactivity of the third-body reaction, H + O2+M=HO2+M, is decreased. The reduced reaction rates of these reactions lead to decreased total exergy loss, indicating that the fuel energy conversion process may benefit from temperature fluctuation.

Body Condition in the Tawny Owl Strix aluco near the Northern Limit of Its Range: Effects of Individual Characteristics and Environmental Conditions.

Simple SummaryThe present study examines how the variations in food supply and winter weather are reflected in the body condition of female and male Tawny Owls Strix aluco of different colour morphs in a population near the southern coast of Finland. Winter weather conditions before breeding seemed to have effects on the food availability of Tawny Owls: the depth of the snow cover showed a positive relationship, and the frequency of temperature fluctuations around the freezing point had a negative relationship. In females, intrinsic factors such as colour morph and age, as well as the body condition of the mate and the stage of the season, governed body condition. In males, only age and the stage of the season suggested associations with body condition. Probably due to the efficient use of alternative prey, the effects of fluctuations of vole populations on the body condition of Tawny Owls are only moderate.The body condition of boreal species of vole-eaters seems to vary largely according to fluctuations in vole populations and weather conditions of the preceding winter. I studied females and males of the Tawny Owl Strix aluco of temperate origin near the northern limit of the species’ range in southern Finland to reveal if they show similar patterns to the boreal species. Winter weather conditions before breeding seemed to have pronounced effects on the food availability of Tawny Owls. In females, intrinsic factors such as colour morph and age, as well as the body condition of the mate and the stage of the season (Julian date), governed body condition. In males, only age and Julian date showed pronounced relationships with body condition. The results suggest that deep snow cover protects vole populations through winter until spring better than a minor amount of snow and that frequent temperature fluctuations around the freezing point in early spring make voles more available for owls that are preparing for breeding. This was also reflected positively in the body condition of female owls. Probably due to the efficient use of alternative prey, the effects of fluctuating vole populations on the body condition of Tawny Owls are, in general, only moderate.

Experimental investigation and semi-empirical correlations for a pulsating heat pipe filling with hybrid nanofluids applied for low-grade energy recovery

Pulsating heat pipe (PHP) is a high-efficiency thermal transportation technology being utilized in the low-grade energy fields. In current work, the novel-hybrid working fluid - graphene oxide nanoplatelets (GO nanofluid) and surfactant solution were jointly utilized to reduce flow resistance and enhance overall thermal performance of PHPs. Sodium Dodecyl Sulfate (SDS) was employed as a surfactant to prepare the water-based surfactant solutions of 500 PPM. The charge ratio was maintained at 60%, vertical bottom heating position of PHP was applied with the power range of 10–100W. Our experimental results illustrated that the oscillation frequency of temperature fluctuation was higher than that with charged GO-SDS hybrid nanofluid in comparison with DI water and pure GO nanofluid. Additionally, maximum average improvement rate of thermal performance 8.55% was successfully achieved in 0.03 wt% GO-SDS hybrid nanofluid than that with pure GO-nanofluid. Furthermore, multiphase fluid flow inside PHP has been comprehensively analyzed, and its flow regimes such as formation of foam and slug, coalescence and breakup of bubbles, and annular flow were observed. On site visualization results illustrated that a fast nucleation of vapor bubbles could be promoted in the evaporator section due to lower surface tension. Specially, a series of bubbles were expected to form cluster for GO-SDS hybrid nanofluid, which further enhanced the oscillation circulation inside PHP. This experimental research and its results could contribute to the optimization and application of PHP.

Numerical simulation of the mixing behaviour of hot and cold fluids in the rectangular T-junction with/without an impeller

• The thermal mixing features in a T-junction with/without an impeller are compared at M R = 0.49. • The mixing behaviour with the impellers are analyzed at different blade numbers and diameters. • The temperature uniformity parameter is defined to investigate the mixing uniformity in the T-junction. • The criterion of mixing length is proposed according to the mass mean temperature. Thermal stratification is the main reason for thermal fatigue failure in the rectangular T-junction. An impeller is set in the mixing zone in the rectangular T-junction to improve the mixing behaviour of hot and cold fluids under the deflecting jet with the inflow momentum ratio of M R = 0.49. Blade numbers and blade diameters are investigated for the range of N p = 2 ∼ 4 and D p * = 0.33 ∼ 0.8, respectively. By the application of large-eddy simulation, the flow fields and temperature fields are obtained in this work. The flow fields show the mixing behaviour between hot and cold fluids can be promoted by setting the impeller with a constant rotation speed, and three flow patterns including the wall jet, deflecting jet and impinging jet will be observed in the T-junction, which is effective for breaking the thermal stratification. Temperature fluctuation and temperature gradient calculated by mean temperature are compared with that of no impeller. It is found that by adding the impeller the temperature gradient is reduced while the temperature fluctuations almost keep the same. The criterion of mixing length is proposed according to the mass mean temperature and the mixing lengths for different conditions are obtained, as well as the temperature uniformity parameter is proposed to evaluate the mixing degree in the T-junction. The results indicate that the relationship between the mixing length and blade diameter is not monotonic and the optimal operating point is around D p * = 0.5 for the impeller of 2 blades. By combining the temperature fields and pressure drops, the results indicate among N p = 2 ∼ 4, the impeller of 3 blades is the best choice. Temperature power spectrum density is also investigated and it is possible to control the critical frequency of temperature fluctuation in the duct by changing the blade numbers.

Phytoplankton Community Performance Depends on the Frequency of Temperature Fluctuations

With increasing frequency and intensity of climate change events, it is crucial to understand how different components of temperature fluctuations affect the thermal tolerance and performance of marine primary producers. We used a controlled indoor-mesocosm set-up to test the effect of a temperature fluctuation frequency gradient on a natural phytoplankton community. Within a frequency gradient, we allowed the temperature to fluctuate from 18 ± 3°C at different rates (6, 12, 24, 36, and 48 h). The temperature fluctuation frequency gradient was contrasted to a constant temperature treatment with the same mean temperature (18°C). Phytoplankton biomass tended to increase with faster fluctuations but was lowest in the diurnal frequency treatment (24 h). In comparison with constant conditions, diurnal or slower fluctuation frequencies showed lower or comparable performance, whereas faster fluctuations showed higher performance. In addition, minor differences in community structure were observed, but species diversity remained comparable over time. Similarly, resource use efficiency and stoichiometry did not change according to fluctuation frequency treatments. We conclude that the effect of temperature fluctuations on phytoplankton biomass depends on the fluctuation frequency; this suggests that the fluctuation frequency determines how organisms average their environments. However, this trend is not driven by species identity but physiological responses. Our results also indicate that phytoplankton communities may be already well adapted to fluctuating environments and can adjust physiologically to temperature variability.

Dimensional Stability Ground Test and in-Orbit Prediction of SiC Telescope Frame for Space Gravitational Wave Detection

Telescope is the key element of space brone gravitational wave detector. Its dimensional stability is required to be better than 1 pm/Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup> at 0.1 mHz. And SiC is the current most likely material for manufacturing telescope with high dimensional stability. Therefore, a potential SiC telescope frame is designed and tested. In addition, in orbit dimensional stability is predicted by a numerical model. The ground dimensional stability of SiC frame is tested with a fiber-based interferometer, and the temperature change data are collected at the same time. The results of which show that when room temperature fluctuation frequency is greater than 10 mHz, the dimensional stability is about 300 pm/Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup> . A numerical model is established which is consistent with the measured data. The in-orbit dimensional stability is evaluated using the numerical model and the thermal environment of Taiji, whose numerical simulation results shows that when space temperature fluctuation frequency is about 0.1 mHz the dimensional stability would be 6.49 pm/Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup> .

Experiments on thermocapillary-buoyancy convection of medium Prandtl number liquids in annular pools heated from inner cylinder

A series of terrestrial experiments on thermocapillary-buoyancy convection of medium Prandtl number liquids (Pr = 6.7-25.2) were performed in annular pools with different depths and a heated inner cylinder. The temperature fluctuation pattern on the free surface was recorded by the schlieren method. Experimental results indicate that thermocapillary-buoyancy convection could weaken and the critical Marangoni number of the flow transition increases with the Prandtl number. When the flow destabilizes, the rotating petal-like structure and the spoke pattern appear respectively in the annular pools with the depths of 4-5 mm and 6-8 mm. As the Marangoni number increases, the flow becomes oscillating as a result of the thermal perturbation induced by the thermocapillary effects. Besides, with the increasing liquid pool depth, the strengthened buoyancy force has an impact on the basic flow and the thermal fields. Thus, the temperature fluctuation frequency of the oscillating petal-like structure is more than that of the oscillating spoke pattern. Different from the cylindrical geometry heated from the outer cylinder, the radial waves and the petals appear respectively near the outer cylinder and the inner cylinder. Furthermore, the wavenumber decreases as the liquid pool depth increases.

Numerical investigation on turbulent penetration and thermal stratification for the in-surge case of the AP1000 pressurizer surge line

The transient three-dimensional in-surge case of the AP1000 pressurizer surge line is investigated by conjugating multi-physics fields under the ANSYS Workbench platform. Through analysis, it is found that there is a notable temperature oscillation in the fluid domain. The frequency of temperature fluctuation at cross sections near the hot leg is around 4.4 Hz, however, there are two peaks in the frequency spectrum at cross sections away from the hot leg. Due to the existence of turbulent penetration, the thermal stratification effect of the surge line under the in-surge case is not drastic, and the temperature difference along paths is less than 10 K. In order to determine the depth of turbulent penetration, four detective methods based on rapid temperature drop, temperature isosurfaces, the swirling strength isosurface and the step change of stress are introduced in this study. At the same time, some sections of interest along which may cracks occur are discussed, which provides a reference for the maintenance of the AP1000 pressurizer surge line.

Thermal-striping analysis methodology for sodium-cooled reactor design

Computational fluid dynamics simulations have been performed to study the applicability of engineering CFD methods for thermals striping analysis. Thermal striping is the fluctuating temperature profile in a solid caused by fluctuating fluid temperature, and the resulting thermal stresses cause high cycle fatigue and eventual material failure. This study presents the methodology for thermal striping analysis, including a transient conjugate heat transfer RANS simulation benchmarked against a sodium triple jet experiment. Multiphysics calculations are implemented to analyze the thermal stresses in the solid domain caused by the coupled heat transfer between the fluid and solid domains. Validation data from a liquid sodium triple jet experiment include time-averaged temperature measurements and power spectra of the temperature signal. The numerical results agree well with these experimental measures, demonstrating key features such as the dominant frequency of temperature fluctuations. The applicability of a low-cost wall treatment method is demonstrated, enabling key computational savings. Finally, the performance of two finite element stress analysis software packages is compared, and the validity of the lower-cost method is confirmed. These results demonstrate the applicability of engineering methods for computational thermal striping calculations, enabling thermal striping estimations in large fluid systems such as the core of a liquid metal-cooled nuclear reactor.

New, improved analysis of correlation ECE data to accurately determine turbulent electron temperature spectra and magnitudes (invited).

Turbulent electron temperature fluctuation measurement using a correlation electron cyclotron emission (CECE) radiometer has become an important diagnostic for studying energy transport in fusion plasmas, and its use is widespread in tokamaks (DIII-D, ASDEX Upgrade, Alcator C-Mod, Tore Supra, EAST, TCV, HL-2A, etc.). The CECE diagnostic typically performs correlation analysis between two closely spaced (within the turbulent correlation length) ECE channels that are dominated by uncorrelated thermal noise emission. This allows electron temperature fluctuations embedded in the thermal noise to be revealed and fluctuation level and spectra determined. We have demonstrated a new, improved CECE coherency-based analysis for calculating the temperature fluctuation frequency spectrum and level, which has been verified both numerically through the simulation of synthetic ECE radiometer data and through analysis of experimental data from the CECE system on DIII-D. The new formulation places coherency-based analysis on a firm foundational footing and corrects some currently published methodologies. This new method accurately accounts for bias error in the coherence function and correctly calculates noise levels for a fixed data record length. It provides excellent accuracy in determining temperature fluctuation level (e.g., <10% error) even for a small realization number in the ensemble average. The method also has a smaller uncertainty (i.e., error bar) in the power spectrum when compared to the more standard cross-power method when evaluated at low coherency. Direct calculation of system noise level using correlation between randomized intermediate frequency signals is recommended.

Impact of Flow Alteration and Temperature Variability on Hyporheic Exchange

AbstractCoupled groundwater flow and heat transport within hyporheic zones extensively affect water, energy, and solute exchange with surrounding sediments. The local and cumulative implications of this tightly coupled process strongly depend on characteristics of drivers (i.e., discharge and temperature of the water column) and modulators (i.e., hydraulic and thermal properties of the sediment). With this in mind, we perform a systematic numerical analysis of hyporheic responses to understand how the temporal variability of river discharge and temperature affect flow and heat transport within hyporheic zones. We identify typical time series of river discharge and temperature from gauging stations along the headwater region of Mississippi River Basin, which are characterized by different degrees of flow alteration, to drive a physics‐based model of the hyporheic exchange process. Our modeling results indicate that coupled groundwater flow and heat transport significantly affects the dynamic response of hyporheic zones, resulting in substantial differences in exchange rates and characteristic time scales of hyporheic exchange processes. We also find that the hyporheic zone dampens river temperature fluctuations increasingly with higher frequency of temperature fluctuations. This dampening effect depends on the system transport time scale and characteristics of river discharge and temperature variability. Furthermore, our results reveal that the flow alteration reduces the potential of hyporheic zones to act as a temperature buffer and hinders denitrification within hyporheic zones. These results have significant implications for understanding the drivers of local variability in hyporheic exchange and the implications for the development of thermal refugia and ecosystem functioning in hyporheic zones.

Experimental investigations on start-up and thermal performance of sodium heat pipe under swing conditions

High-temperature heat pipes (HTHPs) have a potential of being used for passive heat dissipation of marine nuclear reactors in emergency. In order to understand the influence of wave action on the performance of HTHPs, a sodium heat pipe is fabricated and experimentally tested in this work. The effects of low-frequency swing on start-up and thermal performance of this heat pipe are examined and compared with the static state tests. The results show that swinging motion has a negligible influence on the whole start-up performance of the heat pipe, however, it would lead to the small-amplitude periodic temperature fluctuations especially at the evaporator. Temperature fluctuation frequency is nearly corresponding to the swing, and the temperature fluctuation amplitude is increased with the swing amplitude. The steady-state thermal performance is slightly decreased with increasing swing speed and decreasing swing amplitude in terms of thermal resistance under test conditions, but the influence seems negligible as well.

The influence mechanism of melt flow instability on the temperature fluctuation on the crystal/melt interface during Czochralski silicon crystal growth

The temperature fluctuation on the crystal/melt interface during Czochralski silicon crystal growth is firstly investigated with LES method based on the relationship between kinetic undercooling and growth rate. The effects of crystal and crucible rotation on the temperature fluctuation are analyzed. The results show that when crystal counter-rotates with crucible, the temperature fluctuations on the interface and that in the melt close to crystal are more intense compared with co-rotation. The characteristic frequencies of temperature fluctuations on the interface and that in the melt are identical for counter-rotation. However, this consistency of the characteristic frequencies is not obvious for co-rotation. In particular, the temperature fluctuations on the interface are about 0.4 K and 0.7 K for co-rotation and counter-rotation, respectively. Importantly, the influence mechanism of melt flow instability on temperature fluctuation is clarified by the analyses of cross-correlation and local convective heat transport.

Experimental study on complex flow of a binary mixture in Czochralski configurations with different aspect ratios and rotation rates

This paper reported the experimental study on complex flow stability of a binary mixture in the Czochralski configurations subjected to a radial temperature gradient. The working fluid was the n-decane/n-hexane mixture with an initial mass fraction of 50%. Results show that the rotation of crucible and crystal can promote the flow destabilization at a small aspect ratio. However, the crucible rotation can suppress the flow instability at a large aspect ratio. When the thermocapillary Reynolds number exceeds a certain threshold value, the hydrothermal waves, the bud shaped and fringes spokes appear in proper order with the increase of the aspect ratio. Furthermore, the flow patterns are also dependent on the crystal and crucible rotation rates. When the crystal and crucible rotate synchronously, the temperature fluctuation frequency in the binary mixture is nearly the same with that in the pure fluid at a small aspect ratio; however, there is a large difference at a large aspect ratio. Moreover, the temperature fluctuation amplitude in the binary mixture is greater than that in the pure fluid at a small aspect ratio, but it is contrary at a large aspect ratio.

Experimental and computational analysis of thermal mixing characteristics of a coaxial jet

In this study, experimental and numerical analyses have been performed to investigate the mixing behavior of hot and cold fluids for a coaxial jet. Thermal mixing phenomenon is an important issue for many industrial applications, since thermal stress occurs when fluids do not mix completely. Several test cases were considered to investigate the mixing quality and frequency of temperature fluctuations. Computational study was performed using Large Eddy Simulation (LES) turbulence model, since this model is proven in this type calculations. A commercial CFD code, ANSYS-Fluent is used for numerical calculations. The study is performed for governing parameters as ratio of mass flow rate of hot (annular) jet to cold (central) jet and temperature difference between hot and cold jet. It is found that there is a good agreement between experimental and numerical studies with respect to spectral analyses. The dominant frequency of temperature fluctuation is found as 5Hz as compatible with literature. Thermal mixing efficiency increases with increasing temperature difference between hot and cold jet. Also, thermal mixing performance getting better with enhancing flow rate of hot jet in the first half of the channel and the best mixing observed at ṁh/ṁc=2 along second half of the channel.

Accelerated Fat Bloom in Chocolate Model Systems: Solid Fat Content and Temperature Fluctuation Frequency

AbstractChocolate model systems were designed with high‐melting fat (cocoa butter stearin, CB‐S) mixed with low‐melting fats (sunflower oil, canola oil, cottonseed oil, peanut oil) to give 45, 55, and 65 % solid fat content (SFC). Defatted cocoa powder provided a 50 % particulate level in the model chocolates. The effects of SFC, low‐melting fat type and storage temperature fluctuation frequency on bloom whiteness were investigated. Both SFC and storage condition had significant influences on bloom whiteness (p &lt; 0.0001), although the type of low‐melting fat did not (p = 0.1223). Increasing the SFC significantly reduced bloom formation, as did more rapid temperature fluctuations.

Fluctuating Water Temperatures Affect Development, Physiological Responses and Cause Sex Reversal in Fathead Minnows

Natural and human activities can result in both high temporal and spatial variability in water temperature. Rapid temperature changes have the potential to dramatically affect physiological processes in aquatic organisms and, due to their limited mobility, fish early life stages are particularly vulnerable to ambient temperature fluctuations. In this study, we examined how the magnitude and frequency of temperature fluctuations affect survival, growth, development, expression of thermoresponsive genes, and gonadal differentiation in fathead minnows, Pimephales promelas. We exposed individuals (0 to 4 days post fertilization) of known genotypic sex to fluctuations of Δ4 °C over 12-h, Δ8 °C over 12- and 24-h, and three stable temperatures (21, 25, and 29 °C) for up to 45 d. Expression of hsp70 in fish exposed to the highest-magnitude, highest-frequency fluctuating treatment cycled in concert with temperature and was upregulated initially during exposure, and may have contributed to temperature fluctuations having little effect on time to and size at hatching (whole-organism responses). This treatment also caused fish to undergo nondirectional sex reversal. These results indicate that hsp70 may be involved in mediating thermal stress from subdaily temperature fluctuations and that sex determination in fathead minnows can be influenced by cycling temperatures.

Temperature experienced during incubation affects antioxidant capacity but not oxidative damage in hatchling red-eared slider turtles (Trachemys scripta elegans).

Our understanding of how oxidative stress resistance phenotypes are affected by the developmental environment is limited. One component of the developmental environment, which is likely central to early life oxidative stress among ectothermic and oviparous species, is that of temperature. We investigated how incubation temperature manipulations affect oxidative damage and total antioxidant capacity (TAC) in red-eared slider turtle (Trachemys scripta elegans) hatchlings. First, to determine whether temperature fluctuations elicit oxidative stress, eggs from clutches were randomly assigned to either a constant (29.5 °C) or daily fluctuating temperature incubation (28.7 ± 3 °C) treatment. Second, to assess the effect of temperature fluctuation frequency on oxidative stress, eggs were incubated in one of three fluctuating incubation regimes: 28.7 ± 3 °C fluctuations every 12 h (hyper), 24 h (normal) or 48 h (hypo). Third, we tested the influence of average incubation temperature by incubating eggs in a daily fluctuating incubation temperature regime with a mean temperature of 26.5 °C (low), 27.1 °C (medium) or 27.7 °C (high). Although the accumulation of oxidative damage in hatchlings was unaffected by any thermal manipulation, TAC was affected by both temperature fluctuation frequency and average incubation temperature. Individuals incubated with a low frequency of temperature fluctuations had reduced TAC, while incubation at a lower average temperature was associated with enhanced TAC. These results indicate that although sufficient to prevent oxidative damage, TAC is influenced by developmental thermal environments, potentially because of temperature-mediated changes in metabolic rate. The observed differences in TAC may have important future consequences for hatchling fitness and overwinter survival.