Radiative Exchange Research Articles

Building a model of oil tank water cooling in the case of fire

The object of this study is the process of liquid combustion in spillage, and the subject is the temperature distribution along the wall of a vertical steel tank when it is heated under the thermal influence of fire and cooled by water. A system of equations describing the water cooling of the wall of a vertical steel tank under the conditions of the thermal effect of a fire spilling a flammable liquid has been constructed. The system consists of a heat balance equation for the tank wall, a heat balance equation for the water film flowing over the wall, and a mass balance equation for the water film. The equations take into account the radiative heat exchange with the flame, the environment, the internal space of the tank, as well as the convective heat exchange with the surrounding air, the vapor-air mixture, and the liquid inside the tank, as well as between the water film and the wall. The joint solution to the system of equations makes it possible to determine the temperature distribution along the tank wall and the water film at an arbitrary time point, as well as to determine the thickness and flow rate of the water film at a certain point. The finite difference method was used to solve the system of heat and mass balance equations. It is shown that the insufficient intensity of water supply for cooling leads to boiling of water from the film, as a result of which the wall temperature in such areas can reach 300 °C. A delay in the supply of water, even with sufficient intensity, could lead to the establishment of a film-like mode of boiling. In such a situation, the water film is thrown away from the wall, as a result of which the part of the wall below the film boiling zone remains without cooling. The practical significance of the built model is the possibility of determining the necessary intensity of water supply for cooling the tank and the limit time for the start of cooling

Field evaluation of the efficacy of passive radiative cooling infrastructure: A case study in Phoenix Arizona

Radiative properties of shade structures affect their surface temperatures, sensible heat fluxes and longwave and shortwave radiation exchange. In fact, structures with high solar reflectance and thermal emittance have the potential to remain below ambient air temperatures, convecting sensible heat from the air to the surface and then radiating that heat to space—a sort of radiant heat pump.We explore cooling benefits of urban surfaces with high solar reflectance and high thermal emittance radiative cooling films through a field measurement campaign in Phoenix Arizona, USA. The tested films have solar reflectance and selective thermal emittance (in wavelengths 8–13 μm) close to 95 %. We applied films in both before-after and control-test experimental designs on thin metal roofs of park shade structures. We measured surface temperatures, surface heat fluxes, upward- and downward-welling longwave and shortwave radiation, and local weather conditions.Results demonstrate the ability of radiant cooling films to reduce surface temperatures on hot days below ambient air temperatures. Test surfaces with cooling films were an average of 7 °C cooler than control shelter surfaces over the diurnal cycle, reducing sensible heat fluxes into the environment by up to 80 %, and lowering mean radiant temperatures for pedestrians using the shelters by more than 3 °C. It was also observed that the sum of the net reflected shortwave and emitted longwave radiation over the diurnal cycle can exceed the total incident longwave and shortwave radiation on the surface, demonstrating the ability of these materials to radiatively “pump” heat out of the city.

Efficient Computation of Radiative Heat Recovery from Porous Ceramic Monoliths for Efficient Solar Thermochemical Fuel Production

Solar thermochemical hydrogen (STCH) produced by heat-driven water-splitting is a promising route for producing green hydrogen and other zero-emission synfuels. However, the efficiency of STCH must be dramatically increased for it to make an impact on decarbonization efforts. We have previously presented a novel Reactor Train System (RTS) for significantly increasing the efficiency of STCH by employing heat recovery from the redox material and efficient gas exchange processes. In this paper we present a higher-fidelity model for the RTS that accommodates the slow heat diffusion through the STCH redox material. For this purpose, a novel method is introduced for transient modelling of radiative heat in participating media. This method, called GREENER: Generalized Radiation Exchange Factors and Net Radiation, combines the accuracy of Monte Carlo Ray Tracing with the low computational cost of the P1 or Rosseland diffusion approximations. Along with STCH, GREENER has application for modelling volumetric solar receivers, high temperature heat recovery systems like heat exchangers and regenerators, and packed bed reactors. Using the GREENER method, the RTS counterflow radiative heat exchanger is shown to achieve heat recovery effectiveness greater than 70%. The performance of non-uniform porous redox morphologies is evaluated, and high-performing configurations are identified.

Research and prediction of early-age loads in double-block ballastless track structure

Considering the hydration reaction of cement, a finite element model(FEM) of the coupling of temperature and humidity field and chemical field in the early age of the double-block ballastless track structure was established, and a field monitoring test on the early age of track slab was carried out with the newly constructed Fuzhou-Xiamen high-speed railway line as a case to verify the correctness of the FEM. Based on the official meteorological data from China Meteorological Administration (CMA) and the FEM, the dataset of vertical temperature and humidity gradients in the early age of the track slab was constructed, and five machine learning training models, namely, machine learning (MLR), multivariate polynomial regression (MPR), support vector regression (SVR), random forest (RF), and gradient boosted regression (GBR), were adopted to train the temperature gradient model and humidity gradient model for the early age of the track slab. The research results show that: (1) under the combined effect of solar radiation, convective heat transfer, radiative heat exchange and the cement hydration reaction, the temperature loading leads to the susceptibility of the sleepers to diagonal cracking; the humidity loading leads to transverse cracking in the center region of the surface of the track slab; (2) the finite element model with a higher accuracy provided the training dataset for the machine learning model. According to the Spearman correlation coefficient, the input features of the temperature gradient model and the humidity gradient model are determined, respectively; (3) Five ML methods were used to train the temperature gradient model and humidity gradient model, both of which demonstrated good generalization ability with a coefficient of determination(R2) greater than 0.85. Among these methods, GBR and SVR exhibited the best performance; From the perspective of MAPE value, the prediction effect of the temperature gradient training model was better than that of the humidity gradient training model; (4) The curing method and the average value of the relative humidity were the important input features influencing the training models for the temperature and humidity gradient loads, respectively. This finding provided an important guideline for the construction of ballastless track structures.

Cross-sectional zero-dimension temperature model for thin-walled circular tubes in space environment

A sufficiently accurate, yet computationally efficient prediction of temperature field is essential for design of spacecraft structures. This paper presents a model dimension reduction method for thermal analysis of thin-walled circular tubes in space environment, which takes into account radiation heat transfer among the internal surfaces besides heat conduction along the circumferential direction and radiative emission from the external surface. Temperature distribution on the tube cross section is approximated by a series of harmonic functions, so that a one-dimensional problem is reduced to that of zero dimension. The relation between average and perturbation temperatures that depend only on time is broadened to fully coupled one. By comparison to the previous model and the plane finite element model, the accuracy and economy of the new model are illustrated. The results show that internal radiation exchange plays an important role in thermal analysis of thin-walled circular tubes used extensively in spacecraft appendages. Furthermore, differences between present and previous models are analyzed and a two-way analysis of variance is performed to determine the effect of various physical and geometric parameters on the temperature distribution and response of the tubes. The work can be further developed to analyze thermally induced deformation and vibration of spacecraft structures.

The Abrikosov vortex structure revealed through near-field radiative heat exchange

The Abrikosov lattice is a property of type II superconductors in which normal and superconducting carriers coexist and arrange in a regular pattern. Here, we address the question on whether vortex matter, particularly the Abrikosov lattice, influences the local thermal properties of high-temperature superconductors. We find that their optical properties are not only dictated by the order parameter, but also that the near-field radiative heat flux acquires a periodic spatial structure inherited from the Abrikosov lattice. Surprisingly, we predict a radial displacement of the heat flux maxima with respect to the vortexes cores, for temperatures well below the critical one.

Assessing Climate Extremes in Dynamical Downscaling Simulations Driven by a Novel Bias‐Corrected CMIP6 Data

AbstractDynamical downscaling is a widely‐used approach for generating regional projections of climate extremes at a finer scale. However, the systematic bias of the global climate model (GCM) generally degrades the reliability of projections. Recently, novel bias‐corrected CMIP6 data was generated using a mean‐variance‐trend (MVT) bias correction method for dynamical downscaling simulation. To validate the effectiveness of this data in the dynamical downscaling simulation of climate extremes, we carry out three Weather Research and Forecasting (WRF) simulations over Asia‐western North Pacific with a 25 km grid spacing from 1980 to 2014. The dynamical downscaling simulations driven by the raw GCM data set (hereafter WRF_GCM) and the bias‐corrected GCM (hereafter WRF_GCMbc) were assessed against the simulation driven by the European Center for Medium‐Range Weather Forecasts Reanalysis 5 data set. The results indicate that the MVT bias correction significantly improves the climatological mean and inter‐annual variability of downscaled climate extreme indices. In terms of the climatological mean, the WRF_GCMbc shows a 25%–82% decrease in root mean square errors (RMSEs) against the WRF_GCM. As for the inter‐annual variability, the MVT bias correction can improve the downscaling simulation of almost all precipitation extreme indices and 70% of the temperature extreme indices, characterized by the RMSEs' reduction of 1%–58%. The improvements of the climate extremes in terms of the climatological mean in the WRF_GCMbc primarily stem from the improved large‐scale circulation and ocean evaporation in the WRF, which in turn improves the downscaled precipitation and 2 m temperature through the advection, radiation, and surface energy exchange process.

Unravelling the performance of atmospheric radiative transfer schemes in the simulation of mean surface climate in Central Africa using the RegCM5 climate model

AbstractThe theory of radiative transfer in the atmosphere is crucial in the study of climate, because radiative exchanges are at the origin of the atmospheric dynamics. It is therefore important to evaluate this phenomenon in order to be able to take effective measures to tackle climate change. The objective of this work is to evaluate the capability of the RegCM5 climate model to reproduce radiative transfer over Central Africa. The analysis is carried out over a 10‐year period, from January 2002 to December 2011 preceded by 1 year as spin‐up. RegCM5 model were evaluated using the ERA5 dataset for the radiative transfer parameters (the shortwave radiation [SWR], longwave radiation [LWR], cloud cover [CLT], surface albedo [ALB] and surface temperature), as well as CHIRPS dataset for precipitation. Three subregions were identified for more specific analysis of the model, namely the Sahel, Congo basin and Cameroon highlands. Two radiative schemes were used: the radiative scheme of the community climate model (CCM) and Rapid Radiative Transfer Model (RRTM). The assessment of radiative transfer parameters was carried out by examining their seasonal variability and annual cycles using data from two RegCM5 experiments, RegCM5‐CCM3 and RegCM5‐RRTM. Before this assessment, a sensibility analysis to convective schemes carried out with the default RegCM5 radiative scheme (CCM3) shows that Grell scheme with Arakawa and Shulber closure is the best scheme to represent key radiation parameters (LWR and SWR). This convective scheme is therefore used for assessing the two Radiative transfer schemes. Results show that both RegCM5 experiments simulate relatively well the variables linked to radiative transfer for the four seasons of the year. However, RegCM5 with RRTM as radiative scheme depicts better performance over all subregions and seasons, suggesting that the choice of this scheme does not depend on land cover, topography and rainfall regimes in a complex region such as Central Africa.

Validation of CFD models of urban microclimates under high temperature and humidity conditions during daytime heatwaves in dense low-rise areas

In the midst of the ongoing climate crisis, there is a growing need to study the effects of climate on humans, especially those of the microclimates that surround humans and their activities. Various models have been developed to simulate microclimates, but simulation models for densely populated areas experiencing heat waves have shown an issue with simulating temperatures that were too high compared to actual measurements. To overcome these limitations, this study aimed to develop and validate CFD model based on STAR-CCM+ in order to more accurately simulate the microclimate of dense residential areas. To improve the realistic simulation capability found in existing models, the model was designed to include solar radiation, humidity, ground radiation, longwave radiation exchange, heat storage and evaporation due to various urban surfaces, evapotranspiration from vegetation, convection, and heat transfer from buildings. For validation, comparisons were made between the simulation results and the actual measurements during this time. The results showed that the R2 value of the model developed in this study increased from 0.86 to 0.91, indicating that the model was able to reproduce the measured results of the target site well. To avoid overfitting the model, the measurement results of the Han River AWS, another AWS operated by the Korea Meteorological Administration near the target site, were input. It was confirmed that the model reproduced the actual measurements of five locations in the target site well. The R2 of temperature and humidity ranged from 0.96 to 0.98, and wind speed ranged from 0.64 to 0.81.

A solar air receiver with porous ceramic structures for process heat at above 1000 °C – Heat transfer analysis

Abstract Concentrated solar energy can be used as the source of heat at above 1000 °C for driving key energy-intensive industrial processes, such as cement manufacturing and metallurgical extraction, contributing to their decarbonization. The cornerstone technology is the solar receiver mounted on top of the solar tower, which absorbs the incident high-flux radiation and heats a heat transfer fluid. The proposed high-temperature solar receiver concept consists of a cavity containing a reticulated porous ceramic (RPC) structure for volumetric absorption of concentrated solar radiation entering through an open (windowless) aperture, which also serves for the access of ambient air used as the heat transfer fluid flowing across the RPC structure. A heat transfer analysis of the solar receiver is performed by means of two coupled models: a Monte Carlo (MC) ray-tracing model to solve the 3D radiative exchange and a computational fluid dynamics (CFD) model to solve the 2D convective and conductive heat transfer. Temperature distributions computed by the iteratively coupled models were compared with experimental data obtained by testing a lab-scale 5 kW receiver prototype with a silicon carbide RPC structure exposed to 3230 suns flux irradiation. The receiver model is applied to optimize its dimensions for maximum efficiency and to scale up for a 5 MW solar tower.

Tomography of near-field radiative heat exchange between mesoscopic bodies immersed in a thermal bath

Tomography of near-field radiative heat exchange between mesoscopic bodies immersed in a thermal bath

Light Transfers Through a Koch Shape Cloud

AbstractModeling radiative transfer in a 3D cloudy atmosphere is critical to climate projections. A recently developed fast 3D radiation parameterization scheme gains some success in quantifying horizontal radiative transfer through cloud sides using cloud area fraction. Based on 3D Monte Carlo simulations of radiative transfer through an idealized single‐layer cloud with Koch‐shaped fractal geometry edges, here we show that radiative energy transport through cloud sides correlates more significantly with cloud area fraction than with cloud perimeter length. The results exemplify the importance of accounting for the horizontal radiative energy exchanges between cloud‐free and cloudy regions with cloud area fraction. Results from additional sensitivity simulations show that increased cloud vertical extent often enhances cloud‐side sunlight leak more significantly than cloud‐side sunlight interception. At low sun elevations, cloud‐side sunlight interception is enhanced more than cloud‐side sunlight leak does with the increase of cloud mass.

Building a model of heating an oil tank under the thermal influence of a spill fire

The object of this study is the process of liquid combustion in a spill, and the subject of research is the distribution of temperature along the wall and roof of a vertical steel tank that is heated under the thermal influence of a spill fire. The heat balance equation for the wall and roof of the tank with oil product was constructed. The assumption of a small thickness of the wall and roof of the tank relative to its linear dimensions makes it possible to move to two-dimensional differential equations of the parabolic type. The equations take into account the radiative heat exchange with the flame, the environment, the internal space of the tank, as well as the convective heat exchange with the surrounding air, the vapor-air mixture, and the liquid inside the tank. Using the methods of similarity theory, estimates of the coefficients of convection heat exchange of the outer surface of the tank with the surrounding air and the inner surface with the vapor-air mixture and liquid in the tank in the conditions of free convection were constructed. The application of the finite difference method for solving the heat balance equations has made it possible to derive the temperature distribution on the surface of the tank at an arbitrary moment in time. It is shown that the value of the coefficient of convection heat exchange of the liquid exceeds the corresponding value for the air-vapor mixture by (1÷2) orders of magnitude. As a result, the part of the wall located below the oil product level is heated to a temperature of (80÷230) °C depending on the viscosity of the liquid. This occurs despite the fact that the value of the mutual radiation coefficient reaches its maximum value at the lower part of the wall. From a practical point of view, this means that the part of the wall above the level of the oil product in the tank can reach dangerous temperature values, and it should be cooled first. The constructed model of tank heating also enables determining the limit time for the start of cooling of the tank.

Determining cold strain in cold air: a comparison of two methods of partitional calorimetry to calculate heat storage and debt in cold air with mild hypothermia.

We compared two methods of partitional calorimetry to calculate heat storage and heat debt during cold air (0°C) exposure causing mild core cooling. Twelve participants performed a 5 min baseline in thermoneutral conditions (∼22.0°C, ∼50% relative humidity) followed by cold air exposure (∼0°C) until rectal temperature was reduced by ∆-0.5°C. Partitional calorimetry was used to calculate avenues of heat exchange (radiative, convective, and evaporative), heat storage, and heat debt continuously throughout cold exposure. We compared deriving these variables using prediction equations based on environmental and participant characteristics (PCALEquation Method) versus using measurement tools such as humidity sensors and heat flux discs (PCALHeat Flux Method). There were significant differences between methods (all p≤0.001) for determining heat exchange, heat storage, and heat debt. At ∆-0.5°C, PCALHeat Flux Method had greater levels of radiative and convective heat exchange (PCALHeat Flux Method: -143.0±16.8 W∙m2 vs PCALEquation Method: -123.0±12.9 W∙m2, p≤0.001), evaporative heat exchange (PCALHeat Flux Method: -9.0±1.7 W∙m2 vs PCALEquation Method: -4.1±0.0 W∙m2, p≤0.001), heat storage (PCALHeat Flux Method: -15.0±31.0 W∙m2 vs PCALEquation Method: +6.0±25.9 W∙m2, p=0.020), and heat debt (PCALHeat Flux Method: -692.0±315.0 kJ vs PCALEquation Method: -422.0±136.0 kJ, p≤0.001). Overall, this study found the largest discrepancies between the two methods were when the environmental conditions and skin temperature were in high flux, as well as when core temperature was reduced by ∆-0.5°C. The use of PCALHeat Flux Method may be more advantageous to use in the cold to provide a higher resolution measurement of cold strain.

Impact of radiative cooling on the energy performance of courtyards in Mediterranean climate

Radiative cooling has proven to be a useful tool to address the problems of lack of comfort and excessive energy consumption in situations of high temperatures, overheating and heat waves. Likewise, incorporating courtyards in warm climate zones has been found to be highly beneficial in addressing similar challenges. Hence, there is interest in analyzing the combined effects of both: radiative cooling and courtyards. This paper presents an analysis of the impact of the application of radiative cooling on a courtyard using a comprehensive simulation approach that includes a CFD model for the thermodynamic airflow in the adjacent roofs and inside the courtyard, equations for the transient heat conduction through roofs, walls and courtyard slabs, and a hybrid raytracing-radiosity model for the evaluation of the solar radiation reaching the building surfaces and its reflections, both of specular and diffuse origin, and for the calculation of the thermal radiation exchange, especially with the sky. The results show that in the hot season, the courtyard with radiative cooling always provides lower temperatures than the initial courtyard does, with a temperature range of 18.33 °C to 33.78 °C, compared to a range of 19.32 °C to 38.00 °C in the initial courtyard, and producing a greater difference with outdoor temperatures that can reach 12 °C versus 8 °C for the reference case. In addition, it was found that the courtyard with radiative cooling is able to significantly reduce the observed nighttime overheating by providing lower temperatures than the outdoor temperatures in the 50% of the nights studied. It was also found that the thermal loads to achieve indoor thermal comfort in the spaces adjacent to the courtyard were reduced by 63.46% to 69.85%.

A dynamic thermal radiation insulation method for directional solidification of polysilicon

To simplify the structure and reduce the high energy consumption of thermal insulation structures for polysilicon directional solidification equipment, an innovative cavity structure with a mirror and diffuse reflector was designed for thermal insulation. This method uses an internal thermal radiation cavity instead of a traditional insulation layer. Compared with the traditional insulation material, its volume was only 16.6 % of the crucible volume, and the energy consumption was reduced by 8.6 %. A mathematical model of the thermal radiation exchange in the cavity was established and solved analytically. Because of the design of mirror and reflector, the self-adjustment of the thermal radiation intensity and angle in the cavity was theoretically verified. It could automatically “trail” the temperature change on the sidewalls of the melt (crucible), and the dynamic thermal compensation was equivalent to an adiabatic construction. Three comparison experiments with a large ingot (0.9 m × 0.9 m × 0.35 m) were performed. When the cavity height to width ratio was greater than 3.33, the thermal compensation was poor and the quality of the ingot is lower than that of the others. The experiments showed that refractory brick and polished brass are a good combination for creating a cavity.

Assessment of temperature distribution on inclined porous rod with a convective and insulated tip

The following work focuses on determining the temperature profile of porous rod using radiative and insulated tip conditions. In addition, graphs are generated to investigate the impact of several non-dimensional attributes on the distribution of temperature for various modes of energy exchange, such as boiling of nucleates and radiative energy exchange, including the convection-conduction parameter, permeability parameter, and radiation-conduction parameter. ND solve technique is applied to solve the generated nonlinear partial differential equation by using MATHEMATICA. The transient thermal response has been visually presented for various key parameters with ranges p=0,2, Nr=1,5,10, Nc=0.3,0.4,0.5, Pe=0.1,0.2,0.3, Q=0.1,0.2,0.3, Bi=1,2,3. The graphical outcome reveals that temperature distribution is a decreasing function of radiation parameter. Exposure time of the rod to the environment gets short for the enhancement in Peclet number. Initially temperature contours are linear, as time progresses the exponential behavior is developed.

Hydrodynamic simulations of cool stellar atmospheres with MANCHA

Three-dimensional time-dependent simulations of stellar atmospheres are essential to study the surface of stars other than the Sun. These simulations require the opacity binning method to reduce the computational cost of solving the radiative transfer equation down to viable limits. The method depends on a series of free parameters, among which the location and number of bins are key to set the accuracy of the resulting opacity. Our aim is to test how different binning strategies previously studied in one-dimensional models perform in three-dimensional radiative hydrodynamic simulations of stellar atmospheres. Realistic box-in-a-star simulations of the near-surface convection and photosphere of three spectral types (G2V, K0V, and M2V) were run with the MANCHA $-bins. These rates were compared with the ones computed with opacity distribution functions. Then, stellar simulations were run with grey, four-bin, and 18-bin opacities to see the impact of the opacity setup on the mean stratification of the temperature and its gradient after time evolution. The simulations of main sequence cool stars with the MANCHA code are consistent with those in the literature. For the three stars, the radiative energy exchange rates computed with 18 bins are remarkably close to the ones computed with the opacity distribution functions. The rates computed with four bins are similar to the rates computed with 18 bins, and present a significant improvement with respect to the rates computed with the Rosseland opacity, especially above the stellar surface. The Rosseland mean can reproduce the proper rates in sub-surface layers, but produces large errors for the atmospheric layers of the G2V and K0V stars. In the case of the M2V star, the Rosseland mean fails even in sub-surface layers, owing to the importance of the contribution from molecular lines in the opacity, underestimated by the harmonic mean. Similar conclusions are reached studying the mean stratification of the temperature and its gradient after time evolution.

Hot gas impingement and radiation on neighboring surfaces from venting and combustion in a package of 18650 cells

A quasi-steady, CFD-based modeling approach is employed to investigate the heat loading within a small package of twenty-five 18650 Li-ion cells. The quasi-steady approach allows for computationally efficient simulations to capture the compressible and turbulent flow field through the safety vent structure and out into the space surrounding a failing cell. Combustion of vent gases leads to high heat loading on neighboring cells and nearby surfaces. Heat transfer mechanisms within the enclosure include convection from hot gases, radiation from the participating medium, and radiation exchange between surfaces. Simulations provide insight into the magnitude of each heat transfer mechanism, and the spatial distribution of heat flux on nearby cells and surfaces within the pack. The complex geometry of the safety vent geometry resulted in an asymmetric jet flow pattern, which induces highly localized impingement heat transfer on specific cells within the enclosure. Radiation from hot surfaces was more significant than radiation from hot gases and soot to neighboring cells. The quasi-steady simulations may be used in the future to develop reduced-order heat transfer models that include the effects of venting and combustion on propagating failure.

Simulating the Thermal Regime and Surface Energy Balance of a Permafrost‐Underlain Forest in Mongolia

AbstractForests overlap with large parts of the northern hemisphere permafrost area, and representing canopy processes is therefore crucial for simulating thermal and hydrological conditions in these regions. Forests impact permafrost through the modulation of radiative fluxes and exchange of turbulent fluxes, precipitation interception and regulation of transpiration. Forests also feature distinct soil layers of litter and organic matter, which play central roles for the infiltration and evaporation of water, while also providing thermal insulation for deeper ground layers. In this study, we present a new module within the CryoGrid community model to simulate forest ecosystems and their impact on the surface water and energy balance. The module includes a big‐leaf vegetation scheme with adaptations for canopy heat storage and transpiration. Furthermore, we account for the effect of surface litter layers on water and energy transfer. We show that the model is capable of simulating radiation, snow cover and ground temperatures below a deciduous needleleaf forest on a north‐facing slope in the Khentii Mountains in Central Mongolia. A sensitivity analysis of topographic aspect and ecosystem configuration confirms the important role of the litter layers for the energy and water balance of the ground. Furthermore, it suggests that the presence of permafrost is primarily linked to topographic aspect rather than the presence of forest at this site. The presented model scheme can be used to study the development of the ground thermal regime in forests, including the state of permafrost, under different climate, ecosystem, and land use scenarios.