Uneven Temperature Distribution Research Articles

Analysis of two interactive burning droplets with different temperatures

This paper presents a comprehensive theoretical analysis of the interaction between two quasi-steady burning droplets with differing temperatures, sizes and distances, building upon the mass-flux-potential model and flame-sheet assumption. In contrast to existing research, this study introduces a fresh perspective on droplet interactions by considering the different temperatures of the droplets. Utilizing the bispherical coordinate approach, theoretical solutions for the Stefan flow, scalar fields, droplet evaporation/burning rates, interaction coefficients and flame positions have been derived successfully. A comparison with extensive numerical simulations indicates a good agreement between the analytical and numerical results under a variety of conditions. It is revealed that proximity between the droplets causes non-uniform evaporation rates on their surfaces, and in some cases, leads to condensation on the cooler droplet. Notably, when the temperatures of the two droplets differ, this results in an uneven temperature distribution across the flame surface, and increasing the temperature of one droplet substantially elevates the temperature of the nearby flame. This study also establishes a criterion for the transition between different combustion modes, specifically between group and separated combustion. The findings of this study are crucial in deepening our understanding of evaporation and combustion processes, as well as the dynamics of flame spreading, local ignition, and extinction in systems involving multiple droplets.

Heat transfer mechanism of different vortex generators arrangements embedded in heat exchange tubes

Heat exchange is widely used in many fields to improve heat transfer efficiency and save energy, while longitudinal vortex generator (VG) is widely used in many heat transfer heat exchangers. In this work, the effect of VGs with different numbers and different pitch ratios (PR) on the heat transfer characteristics in the tube was studied numerically. The results show that when the fluid flows through the VG, the reflux region will be generated, and the fluid velocity in the reflux region will be inhibited, resulting in uneven temperature distribution and increased Nu. When multiple VGs are arranged in a row, the number of vortices is increased, and the area affected is increased. This improves the overall heat transfer performance. With the decrease of PR, the number of VG rows increases, and the heat transfer performance increases first and then decreases with the decrease of PR.

Multi-scale investigation of heat and momentum transfer in packed-bed TES systems up to 800 K

With the rising cost of energy and the advancement of corporate social responsibility, there is a growing interest in addressing the challenge of recovering and storing high-temperature waste heat. Sensible heat storage in packed beds stands out as a cost-effective and seemingly straightforward solution for high-temperature Thermal Energy Storage (TES). Engineering models developed to design low-temperature TES systems were tentatively used to design this new generation of high-temperature systems. Delving into the physics of coupled heat and mass transfer reveals a lack of validation of this approach. This study seeks to establish a comprehensive bottom-up methodology - from the particle scale up to the system level - to provide informed and validated engineering models for the design of high-temperature TES systems. To achieve this goal, we developed a multi-scale numerical model to explore the physics of heat and momentum transfer in packed-bed TES systems. At the microscopic scale (pore/particle), we consider the flow of a compressible high-temperature gas between the particles, coupled to transient heat conduction within the particles, with particular attention given to incorporating accurate temperature-dependent viscosity for the gas phase and thermal conductivity and density for both solid and gas phases. At the macroscopic scale (engineering), we propose a high-temperature extension of state-of-the-art two-equation TES models. The governing equations considered are the volume-average conservation laws for gas-mass, gas-momentum and energy of both phases. The multi-scale strategy is applied to a randomly packed bed of spherical particles generated with the discrete element method (DEM) software LIGGGHTS. Numerical models for both scales were implemented in the Porous material Analysis Toolbox based on OpenFoam (PATO), which is made available in Open Source by NASA. Microscopic scale simulations were used to infer the effective parameters needed to inform the macroscopic model, namely, permeability, Forchheimer coefficient, effective thermal conductivities, and the heat transfer coefficient. The informed macroscopic model reproduces with excellent accuracy the average temperature fields of the physics-based microscopic model. Pore-scale analysis shows highly three-dimensional flow characterized by reverse flow and strong cross-flow in the packed bed system. Moreover, it indicates the coupling between temperature and velocity fields, where a nonuniform velocity field results in uneven temperature distributions across the fluid and the solid spheres within the packed bed, subsequently affecting the macroscopic heat transfer coefficient. The overall strategy is validated by comparison to available experimental data. This bottom-up methodology contributes to the understanding and opens new perspectives for a more precise design and monitoring of high-temperature TES systems.

Design of Cookware Induction Plate

An optimum temperature distribution at the bottom of the cooking vessel is necessary to enhance the cooking experience for induction heating users. Traditional ferromagnetic cookware has good efficiency in heating surfaces but uneven temperature distribution with flat inductors, which ultimately leads to inequitable cooking outcomes. To address this issue, the paper proposes an alternative solution by incorporating different designs of cookware. The paper describes the analysis and design of cookware using the finite element method to improve the temperature distribution of the cookware. This paper explains the temperature distribution and magnetic flux distribution at the bottom of the cookware. The results demonstrate that the proposed solution achieves a well-balanced trade-off between efficiency and even temperature distribution at the bottom of the induction cookware.

Gear-Shaped High-g Combustion Chamber for Micro Turbojet Engine Applications.

Enhancing combustion efficiency and optimizing the thrust-to-weight ratio are critical technical challenges encountered in the development, application, and growth of micro turbojet engines. The high-centrifugal (high-g) combustion chamber, as an innovative combustion chamber system, has the capability to replace the primary combustion chamber of the traditional turbojet engine, reducing the length of the combustion chamber while maintaining engine performance. Previous studies on the structure of the high-g combustor (HGC) have shown problems such as uneven temperature distribution of the turbojet rotor. To improve the feasibility of HGC integration into micro turbojet engines, this study conducts relevant experiments on a 120 N thrust engine. Subsequently, the results of these experiments were used to analyze the structural design of HGC through a simulation approach. Including six main configurations, the first four structural designs focused on establishing a suitable highly centrifugal environment to stabilize and improve the combustion performance, which was successfully achieved by designing the outer ring gear-shaped inlet with four different angles. Subsequent structural designs were based around improving the uniformity of the temperature distribution at the combustion chamber outlet. The final design of the HGC combustion efficiency is not much different from the original combustion chamber, and it can shorten the axial length of the combustion chamber by nearly 30%. The design of the air inlet holes and the baffle plate effectively improves the temperature uniformity at the outlet of the combustion chamber. Moreover, without changing the combustion chamber material, the corresponding engine weight can be reduced by about 10.7%, and the engine thrust-to-weight ratio can be improved by up to 12% with the same thrust, which provides design ideas for further lightweight applications.

Investigation of pin and perforated heatsink cooling efficiency and temperature distribution

AbstractThe uneven temperature distribution resulting from thermal stresses in heat sinks is a significant issue in modern electronic devices. This numerical investigation utilizes fluid to analyze the cooling, flow, and heat transfer characteristics of eight different heat sink designs. These include pin–fin heat sinks with circular, triangular, square, and hexagonal cross-sections, as well as their perforated versions. The results show that the thermal resistance range for all geometries was between Rth = 0.29 and 0.51 K W−1. The circular cross-section pin structure was found to be the most efficient in terms of thermal resistance, while the triangular perforated structure was the least efficient. The narrow and low temperature distribution indicates a high cooling potential for the heat sink. It has been observed that the temperature range studied is between 308.732 and 315.273 K. The circular cross-section pin structure is most efficient in terms of homogeneous distribution between 308.73 and 311.306 K. The pin-type structure with a square cross-section attained the maximum Performance Evaluation Criteria (PEC) of 1.1872 at P = 689 Pa, while the pin-type structure with a triangular cross-section attained the lowest PEC of 0.67 at P = 2750 Pa. The investigation revealed that, in relation to PEC, perforated structures had superior performance compared to other pin designs, except for the square-section pin structure. This research found that measuring the efficiency of a heat sink based just on thermal resistance or average temperature distribution is not enough; the PEC criteria must also be taken into account.

Temperature uniformity analysis and multi-objective optimization of the microchannel heat sink with cavities under longitudinal vortex flow

With the development of electronic devices toward a more centralized direction, there is an urgent need to introduce new technologies in the microchannel heat sink to address thermal deformation or failure caused by uneven temperature distribution. Therefore, microchannels with longitudinal vortex generators (LVGs) and different shapes of cavity structures combination are designed innovatively to address this issue. The laminar flow solver solves for single-phase, steady, and fully developed liquid flows through microchannels in the inlet Reynolds number range of 168–793. Study finds that the longitudinal vortex flow not only mixes the fluid in the mainstream region but also effectively weakens the retention effect in the cavities. Among all microchannels, the microchannel with LVGs and triangular cavities combination (MC-LTC) shows the best performance. Subsequently, multi-objective optimization of the MC-LTC is carried out using Non-dominated Sorting Genetic II Algorithm with the pumping power (Pp) and the temperature uniformity factor (E) as objective functions, and the relative heights (α, β, γ) of the three pairs of LVGs as the three design variables. The optimal solutions set for Pp and E range from 0.706 mW to 1.018 mW and 0.547 to 0.716, respectively. Among the five selected Pareto optimal solution parameters, MC-LTC (α = 0.6001, β = 1.3528, γ = 1.3707) and MC-LTC (α = 0.6001, β = 1.0725, γ = 1.3017) show the best temperature uniformity performance.

Urban heat island patterns in garden cities: Putrajaya as a case study

The garden-city model, characterised by sprawling urban expansion and extensive open spaces, features green and water surfaces alongside substantial road networks, large parking lots and unshaded lands. This diverse landscape contributes to uneven air temperature distribution within the city. Our study investigated urban heat island (UHI) patterns in various urban environments within Putrajaya, focusing on rural, business, residential and near-water areas. Atmospheric data were collected over a year. Putrajaya exhibits two distinct UHI patterns: cool-day-hot-night in residential zones and hot-noon-temperate-elsewhere in impermeable areas. Business areas display alternating patterns based on seasonal climatic conditions and anthropogenic factors. The efficacy of artificial water bodies as a UHI countermeasure in garden cities depends on the size of the water body and the nature of the surrounding land cover. Shaded and green areas exhibit UHI intensities limited to 3°C, while impermeable areas, regardless of proximity to water surfaces, experience UHI up to 6°C. Overall, the garden-city model tends to restrict UHI variations within −1 to 3°C compared to −2 to 4°C in nearby Kuala Lumpur.

A Review on Cooling Methods of Lithium-Ion Battery Pack for Electric Vehicles Applications

The thermal concerns, such as capacity loss, uneven temperature distribution and thermal runaway of the battery packs made of lithium-ion batteries (LIB) used in electric vehicles (EV), limits its applicability, especially in situations of high-power demand. This article analyses the causes of heat generation in lithium-ion battery packs, focusing on their dominance over total heat generation. It discusses the thermal issues arising from heat generation, their root causes, and influencing parameters. Further, it examines the effect of cooling systems on peak battery temperature and temperature uniformity, as well as their design, operating, and performance parameters. The review suggests that, when designing a cooling system, entropic heating should be considered alongside Joule heating during low discharge rates and high temperatures, which are the conditions that prevail when an EV cruises on highways in hot weather. Capacity fade of battery is caused by temperature-dependent factors such as the growth of the SEI layer, rise in separator resistance, and active material loss. Hence an effective battery cooling system should maintain a temperature range of 15°C to 35°C and ‘ΔTmax’ below 6°C. Out of the reviewed cooling systems, air cooling is found to be simple and cost effective, but inefficient for large battery packs. PCM based cooling technique offers greater temperature uniformity but is sensitive to melting point. Liquid cooling is most efficient but adds cost and complexity. Evaporative cooling can serve as a middle ground between air and liquid cooling with further research to put it into practice. The future research in battery thermal management may focus lowering the energy consumption of the cooling systems by taking into account, the precise cooling needs as per the modes of battery operation.

Reduced order model for flow distribution in tapered headers of U-type heat exchangers

Flow maldistribution in the channels of plate heat exchangers (PHEs) results in uneven temperature distribution leading to thermal distortion of the plates, increased pressure drop, and reduced thermal efficiency. Ensuring a uniform flow distribution is paramount for the efficiency and reliability of these systems. Using a modified header shape has the potential to improve flow conditions. To date, there is no mathematical model to predict flow distribution for tapered headers in PHEs. In this context, a reduced-order model has been developed to rapidly assess the potential impact of tapered headers on flow distribution. This model marks a pioneering effort in developing a comprehensive model for estimating flow distribution and pressure drop applicable to both uniform and tapered headers of U-type PHEs, providing valuable insights without necessitating significant computational resources. Key structural parameters, such as header diameter, number of channels, channel area, and taper ratio, that influence flow distribution have been identified by solving the differential equations numerically. For tapered headers, a more uniform flow distribution occurs with fewer plates for the same flow resistance, i.e., the average total head loss coefficient (ζ). Beyond a critical header diameter, the flow remains nearly uniform, regardless of the ζ value. For higher ζ values, there is a channel area range where flow uniformity either increases or remains nearly uniform. One of the most significant findings is the identification of the conditions where tapered headers provide more flow uniformity compared to straight headers. Validated by existing literature, this model shows promising practical applications in the rapid design and optimization of plate heat exchangers.

Design and Optimization of a Mixed-Flow Drying Chamber for Tiger Nuts Based on CFD-DEM Heat and Mass Transfer Model

In order to solve the problem of inconsistent moisture content in particles during the drying process of tiger nuts (Cyperus esculentus) due to uneven air flow and temperature distribution in the drying chamber, an open-hole corner box was designed based on the principle of negative pressure micro-perforated air supply. Using computational fluid dynamics (CFD) and discrete element method (DEM) simulation, coupled with the basic theory of interphase heat and mass transfer, a mathematical model for interphase heat and moisture coupling transfer was established. The effects of different aperture rates of corner boxes in the drying chamber, spatial location arrangement, and other related variables on the airfield distribution, temperature field distribution, tiger nut temperature, and moisture content changes were investigated. The results show that the average air velocity below the air inlet gradually increases as the opening ratio increases. When the opening rate is 0.33%, the wind field uniformity is better, and the inhomogeneity of the drying chamber wind field is improved. As the lateral distance increases, the consistency of the moisture content distribution increases and then decreases, and the flow rate of the tiger nuts gradually increases when the grain is discharged. The rate of decrease in water content decreases gradually with the increase in longitudinal distance. When the wind speed reaches 4 m/s, the drying chamber wind field is more uniform, and the water vapor diffusion efficiency at the outlet is basically the same. Therefore, the appropriate corner box has a horizontal distance of 320 mm and a longitudinal distance of 420 mm, providing a basis for the design of tiger nut drying equipment.

A novel thermal-fluid topology optimization of the frame mold for composite autoclave process

Frame mold serves as an important tool during autoclave process of composite panels. Its temperature uniformity plays a crucial role in guaranteeing the production quality. However, the temperature uniformity of mold usually has to be sacrificed during the design process for ensuring the stiffness of mold. To solve this problem, a novel design strategy is proposed in this study to optimize the heating airflow channels of mold with better temperature uniformity based on thermal-fluid topology optimization method. Firstly, the temperature and the airflow distribution characteristics of mold during autoclave process are investigated systematically based on the Computational Fluid Dynamic (CFD) simulation model. The result indicates that the uneven temperature distribution of the mold during autoclave process is significantly affected by the varying airflow velocity distribution inside the mold. Inspired by this, a thermal-fluid topology optimization method is developed to design the airflow channels of mold to achieve optimal mold temperature uniformity. The optimization result provides a novel configuration of mold in which a ‘wind deflector’ is incorporated inside the mold to alter the airflow pattern. Finally, the simulation results show that the optimized mold with a ‘wind deflector’ significantly improves the mold temperature uniformity by 16%. And experimental validation has applied to confirm the effectiveness of the results. Besides, the configuration of the optimized mold has good industrial application prospects for its convenient installation process and low cost.

Analysis of Tangential Leakage Flow Characteristics in a Variable Diameter Dual Circular Arc Vortex Compressor

(1) To address issues such as a low compression ratio and severe leakage in uniform wall thickness vortex compressors, this paper adopts a new scroll compressor model with a variable diameter double arc combined profile, which has a larger pressure ratio and smaller leakage than the scroll compressor with equal wall thickness that can bring new ideas and methods to the research in the field of scroll compressors. (2) This paper determines the theoretical equation of the variable diameter dual circular arc vortex profile and the combined profile, and infers mathematical models for the leakage line length, working chamber volume, and gas leakage per unit rotation angle of the vortex compressor, followed by simulation. (3) The results show that compared to the uniform wall thickness involute profile, the variable diameter dual circular arc combined profile model reduces the leakage line length by 25%, increases the average total pressure at the working chamber outlet by 2.38%, and decreases the leakage amount by 3.2%, consistent with theoretical analysis. (4) The tangential leakage caused by the radial gap in the variable diameter dual circular arc combined profile model has a significant impact on the uneven distribution of temperature and velocity fields in the working chamber of the vortex compressor, but a smaller impact on the pressure field.

Generation and Suppression of Pendant Droplet Oscillation in Electron Beam Directed Energy Deposition

Electron beam–directed energy deposition (EB–DED) has emerged as a promising wire-based metal additive manufacturing technique. However, the effects of EBs on pendant droplets at wire tips have not yet been determined. The aim of this study is to enhance the understanding of this action by analyzing the mechanism of droplet oscillation. The pendant droplet oscillation phenomenon hinders the stable transfer of droplets to the molten pool and limits the feasibility of manufacturing complex lattice structures by EB–DED. Hence, another aim of this study is to create an oscillation suppression method. An escalating asymmetric amplitude is the main characteristic of droplet oscillation. The primary oscillation-inducing force is the recoil force generated from the EB-acted local surface of the droplet. The physical mechanism of this force is the rapid increase and uneven distribution of the local surface temperature caused by the partial action of the EB. The prerequisites for droplet oscillation include vacuum conditions, high power densities, and bypass wire feeding processes. The proposed EB–dynamic surrounding melting (DSM) method can be applied to conveniently and effectively suppress oscillations, enable the accurate transfer of droplets to the molten pool, and achieve stable processes for preparing the strut elements of lattice structures. Lowering the temperature and improving the uniformity of its distribution are the mechanisms of oscillation suppression in EB–DSM. In this study, the physical basis for interpreting the mechanism by which EBs act on droplets and the technical basis for using EB–DED to prepare complex lattice structure parts are provided.

Effect of underwater vehicle wake on sound propagation characteristics in stratified medium

Due to the uneven distribution of seawater temperature and salinity, the density distribution at different depths is different, thus forming a density step layer with a certain gradient. Acquiring the wake internal wave field generated by underwater vehicles passing through this layered structure and mastering its modulation characteristics for the sound field can provide new technical support for the tracking and identification of underwater vehicles. In this paper, the real size model of a certain type of underwater vehicle is taken as the research object to explore the characteristics of its wake internal wave field, and the influence of navigation parameters on the wake field and the change of winning characteristics under the influence of internal waves are simulated and analyzed. The results show that the navigation parameters of underwater vehicles have obvious influence on the wake field, and then have specific influence on the sound field structure in a certain range, especially on the sound signal of the sound field.

INVESTIGATION OF THE EFFECT OF TEMPERATURE FIELDS OF DELAYED COKING REACTOR BODIES ON THE STRESS-STRAIN STATE OF THE MATERIAL

The article continues to explore the topic of damage to DCR (delayed coking reactors) or coke drums during operation. Based on the temporary localization of damage formation during the cooling stage, the most critical stage of the technological process during the operation of the DCR is determined and a damage mechanism is proposed in the form of the influence of an uneven temperature distribution over the DCR body. The description of method for studying the temperature field on the outer surface of the body of the DCR using original mobile temperature measuring devices is given. The results of research with data on the distributions and actual values of temperature differences along the outer surface of the body of the DCR during operation are presented. The DCR with a material design made of stainless steel was selected as the object of research. The case of damage in the form of cracking of the welded joint of the body during the operation of the DCR with the occurrence of a leak is considered. To justify the occurrence of damage in the form of corrugations, calculations of the stress-strain state (SSS) of the material of the body elements are carried out. The applied finite element complex «ANSYS» is used for calculations. As the initial data for SSS calculations, the results of studies of the temperature distribution over the outer surface of the DCR are used. During the calculations, it was found that at the cooling stage, the greatest stresses in the body material correspond to the level of the yield strength of the material and lead to irreversible plastic deformation with the occurrence of the process of accumulation of deformations (ratcheting process). A comparison is being made with data from foreign studies of the operating conditions of the DCR. As measures to prevent operational damage to the DCR, it is proposed to change the technical requirements for steels for the manufacture of main parts in terms of increasing the level of mechanical properties (tensile strength and yield strength). Recommendations are formulated on the material execution of the DCR, the design and manufacture of the DCR.

Visualization of temperature distribution and flow behavior in water evaporation using water‐soluble spiropyran

AbstractUnderstanding the convection flows driven by the uneven temperature distribution in heated aqueous solutions is fascinating and meaningful both in fundamental and industrial aspects. Therefore, it is desirable to develop a simple and convenient method for real‐time tracking of surface temperature distribution and the solvent flow state. Herein, we designed and screened a water‐soluble spiropyran derivative (BS‐SP1) that contains benzothiazole and sulfonic acid groups. The BS‐SP1 molecule was found to exceptionally maintain the reversible photochromic characteristics in water, and then served as a photo‐responsive indicator for visualizing the temperature distribution and flow behavior on water surface with high resolution. This study provides feasible guidance on the dynamic self‐assembly and thermodynamics occurring in the water evaporation system and offers a practical tool for investigating these behaviors.

Investigation of loading intensity effect (LIE) on the failure mechanism of shield tunnel subjected to fire

The overload damage seriously threatens the service life of the tunnel structure, and the elevated temperatures under the extreme load of fire pose a more serious threat to the structure. In this study, a thermal–mechanical methodology is proposed to analyze the combined effects of loading intensity and fire on tunnel structures. The methodology is also validated by experimental studies. Impacts of loading intensity effect (LIE) on temperature distribution, deformation development and inner force distribution are discussed respectively. Results indicate that LIE aggravates heat flow invasion, making uneven temperature distribution of the segmental ring. On the other hand, LIE has a direct influence on the development of mid-span deformation of lining segments, and induces the failure of lining segments due to excessive deformation at the initial stage of heating. higher loading intensity induces a higher initial axial stress level of the tunnel structure. It is also found that the failure of the segmental ring can be attributed to the development of plastic hinges originated from the coupled thermo-mechanical effect. The findings not only reveal the combined effects of overload damage and fire on tunnel structures, but also provide valuable insights on fire prevention in case of tunnel fire.

A Review of Polymer-Based Environment-Induced Nanogenerators: Power Generation Performance and Polymer Material Manipulations.

Natural environment hosts a considerable amount of accessible energy, comprising mechanical, thermal, and chemical potentials. Environment-induced nanogenerators are nanomaterial-based electronic chips that capture environmental energy and convert it into electricity in an environmentally friendly way. Polymers, characterized by their superior flexibility, lightweight, and ease of processing, are considered viable materials. In this paper, a thorough review and comparison of various polymer-based nanogenerators were provided, focusing on their power generation principles, key materials, power density and stability, and performance modulation methods. The latest developed nanogenerators mainly include triboelectric nanogenerators (TriboENG), piezoelectric nanogenerators (PENG), thermoelectric nanogenerators (ThermoENG), osmotic power nanogenerator (OPNG), and moist-electric generators (MENG). Potential practical applications of polymer-based nanogenerator were also summarized. The review found that polymer nanogenerators can harness a variety of energy sources, with the basic power generation mechanism centered on displacement/conduction currents induced by dipole/ion polarization, due to the non-uniform distribution of physical fields within the polymers. The performance enhancement should mainly start from strengthening the ion mobility and positive/negative ion separation in polymer materials. The development of ionic hydrogel and hydrogel matrix composites is promising for future nanogenerators and can also enable multi-energy collaborative power generation. In addition, enhancing the uneven distribution of temperature, concentration, and pressure induced by surrounding environment within polymer materials can also effectively improve output performance. Finally, the challenges faced by polymer-based nanogenerators and directions for future development were prospected.

Study of Temperature Gradients in Concrete Products in the Process of Their Heat Moisture Treatment

Statement of the problem. The work is devoted to the problem of improving the technological process of production of concrete products, in particular, improving the performance of the stage of their heat and moisture treatment. As such indicators, the spatial and temporal temperature gradients in the thickness of the concrete product are chosen, the excess of which exceeds the maximum allowable values for this type of concrete and adversely affects the strength of the product. On the other hand, steam-moisture treatment of products with obviously low values of these gradients leads to an increase in the time of the considered stage of the technological process, i. e. to reduce line performance. In this regard, the task was set to quantify the temperature gradients in the sections of concrete products in the process of their heat and moisture treatment by using the appropriate mathematical model. Results. As a result of studies carried out on the model of temperature fields in the longest mode — cooling mode, a significant uneven distribution of temperature at the boundaries of the «concrete-air» media was shown and critical zones of these fields in the sections of products and time intervals of their existence were identified. Conclusions. A conclusion was made and confirmed on the expediency of reducing the temperature in the chamber according to the exponential law and on the need to control its gradients in the critical sections of products.