Pipe Spacing Research Articles

Optimization of cooling system parameters with temperature field of mass concrete during hydration

Embedded cooling pipe system is regarded as the primary means in mass concrete to control the temperature. The effects of three factors are investigated on the thermal field of mass concrete by the combination of measurement, theoretical analyse and numerical simulation in this paper, including cooling pipe spacing, pipe diameter and pipe arrangement. The results demonstrate that the peak temperature is reduced by the increase in both of the pipe distance and pipe diameter. The peak temperature is measured to decrease from 1°C to 3°C on the monitoring points, with additional 0.5 m of pipe spacing or 10 mm of pipe diameter. The serious influence is conducted by the pipe diameter on the temperature difference, and the selection of cooling pipe diameter is considered to balance multiple problems in the project necessarily. The serpentine arrangement is more widely used for better cooling and construction in the comparison of the circular arrangement. The results on the optimization of cooling system are utilized for the project to control the hydration heat accurately and reduce or even prevent the generation of cracks.

Comprehensive analysis of thermal performance and low-grade energy charging efficiency of pipe-embedded building envelopes enhanced with single-level tree-shaped fin structures

Pipe-embedded walls (CnPWs) are structural and energy composite building components that can resist external disturbances by forming stealth thermal shielding layers. To tackle the mismatch between the heat charging rate and heat diffusion rate during energy charging processes, as well as the unsatisfactory robustness of stealth thermal shielding layers, the single-level tree-shaped metal finnd pipe-embedded walls (TfPWs) are proposed. To verify the effectiveness of TfPWs and obtain dynamic performances, a simulation study is conducted on 8 risk variables in 4 pairs through the validated numerical model. Results showed that the improved design was effective in obtaining more robust thermal shielding layers in auxiliary energy supply mode, the effect gained prominence as both the injection temperature and pipe spacing were augmented. In room heat load reduction mode, favorable benefits arise when pipe spacing exceeds 400 mm. The maximum increase rate of total injected energy under different reduction ratios of external insulation layer was 11.83%–31.91 %, while the maximum extra total heat loss was 5.33 %. Secondly, the trunk fins and branch fins played different roles in minimizing the excessive heat accumulation surrounding pipes, and the vertical and horizontal sizes of heat accumulation region mainly increased with the increase in trunk fin size and branch fin size respectively. Meanwhile, the utilization efficiency of fin material was higher when trunk fin size was smaller, and parameter combinations with trunk fin size of 0.2b and branch fin size of 0.4a/0.6a could achieve a better balance between material input and performance increase. Thirdly, the improvement effect of single left branch fin schemes was close to that of double branch fin schemes and significantly better than that of single right branch fin schemes. It was recommended to use single left branch fin schemes with an inclination angle of 60°. Finally, even if the reduction ratio of external insulation layer in different cities increased to 80 %, the inside surface temperature of TfPWs was still greater than room air. Taking CnPWs with standard external insulation layer as references, the TfPWs applied in Harbin, Beijing, and Shanghai could achieve similar or better results even when the reduction ratio of external insulation layer increased to 60 %, while TfPWs applied in Guangzhou could exhibit better performance even when the reduction ratio of external insulation layer increases to 80 %.

Techno-Economic Feasibility Study of Earth Air Heat Exchangers for Gas Turbine Inlet Air Cooling

In response to pressing energy crises and environmental concerns, enhancing the performance of existing energy conversion systems, such as gas turbines, and tapping into renewable resources have become critical imperatives. Escalating ambient temperatures poses a notable challenge, hampering the efficiency of gas turbines. This study rigorously explores the feasibility of earth-to-air heat exchangers (EAHEs) as a pragmatic solution to cool gas turbine inlet air. The primary objective is an exhaustive techno-economic analysis evaluating the long-term operational viability of EAHE systems. Employing the Taguchi method, the study optimizes the system geometry and pipe arrangement, focusing on four key control factors: pipe diameter, spacing, length, and depth. The pivotal optimization criterion is the levelized cost of energy (LCOE), encompassing thermal performance and economic viability. The net present value (NPV) and Discounted Payback Period provide supplementary insights into the economic prospects. Integral to the study is a novel and intricate hybrid analytical-numerical model that simulates the long-term transient operation of EAHE. Findings from a detailed case study unveil an optimized scenario yielding an LCOE amounting to 0.071 $/kWh, accompanied by a substantial NPV of 4.5 million dollars.

Modeling the Optimal Distance Between Pipes in a Solar Water Heating Collector

This study proposes a mathematical model based on normal distribution to determine the optimal distance between pipes in a solar water heating collector. The model takes into account key system parameters such as material thermal conductivity, heat losses, and solar radiation intensity. Experimental data collected for model validation confirm its accuracy and adequacy. The main results show that the maximum efficiency (η) of the solar water heating collector is achieved at a pipe spacing of approximately 0.0469 m. The analytical method demonstrates a smooth decrease in efficiency when deviating from the optimal distance, whereas the experimental data indicate a high sensitivity of the system to changes in this parameter. Thus, the proposed model is a useful tool for designers, allowing for precise prediction of optimal system parameters and increased efficiency. Further research and experiments are planned to improve model accuracy and expand its applicability.

Numerical study on comprehensive performances of pipe-embedded building envelope integrated with arc-finned heat charging system

In the context of accelerating toward carbon neutrality, building envelopes are gradually regarded as multifunctional units with structural and energy attributes. To address the capacity mismatch between heat injection and thermal diffusion processes that hinder performance improvement of pipe-embedded energy walls, the arc-finned pipe-embedded energy walls (i.e., Arc-finPEWs) with directional heat-charging capacity are put forward. Subsequently, a validated mathematical model is established to explore the transient thermal behaviors of Arc-finPEWs as well as the impacts of 7 key parameters on its energy-saving potentials. Results showed that the directional heat-charging measures could improve the heat-charging capacity in specified directions, and the enhancement effect was more obvious as pipe spacing increased. Besides, the fin number (FN), shank length (SL), and fin angle (FA) were the top three influencing parameters in auxiliary-heating mode, whereas impacts of FA, FN, and arc angle (AA) ranked the top three in load-reduction mode. Furthermore, a larger FN and SL contributed to reducing total primary energy consumption and creating more robust invisible thermal barriers in auxiliary-heating mode, while left-facing fins or SL settings that are too high or too low were unfavorable in load-reduction mode. Meanwhile, the arc-fin designs with SL=0.6, FA=150° and AA=30° in auxiliary-heating mode and FA=30°, SL≤0.4 and AA≤15° in load-reduction mode are suggested. Compared to conventional energy-saving walls, the proposed arc-finned heat-charging system could reduce physical thermal insulation material usage with high embodied carbon features by over 60 %.

Experimental study and numerical simulation of concrete pavement electrical heating for snow melting

Road snow accumulation can lead to severe traffic delays, and commonly used deicing agents may pose potential environmental risks. Electrically heated concrete pavement systems utilizing heating pipe technology offer a safe and environmentally sustainable alternative. The snow-free ratio was frequently used as an evaluation index to evaluate the snow-melting performance in road infrastructure. However, the unique wavy temperature distribution during the snow-melting process of the heating system results in discontinuous melting, making the existing snow-free ratio inadequate for accurately assessing its performance and effectively guiding the operational strategy of the heating system. Therefore, this study analyzed the special temperature distribution and proposed a new calculation method for snow-free ratio based on the average temperature and the temperature non-uniformity coefficient of the pavement surface. First, the effects of factors such as heating pipe spacing, embedded depth, heating power, and wind velocity on average temperature and the temperature non-uniformity coefficient were analyzed using finite element simulation. Prediction models for average temperature and the temperature non-uniformity coefficient were then established and validated using the response surface method and experiments. Subsequently, using average temperature and the temperature non-uniformity coefficient as intermediate variables, a new functional relationship between the snow-free ratio and the four factors was established, allowing for satisfactory snow-melting performance to be achieved by adjusting the relevant factors of the heating system. The results show that the error rate between the proposed new calculation method and simulation results is only 4.44 %. Moreover, it was concluded that adjusting spacing and heating power is the most effective strategy for heating systems to achieve optimal snow-melting performance.

Investigation on evolution law of frozen wall thickness in artificial ground freezing under seepage conditions

Frozen wall thickness (E) is an important index that reflects the freezing performance of artificial ground freezing (AGF). In previous design and numerical studies, the inherent spatial variability of soil properties is often neglected. Moreover, groundwater seepage can remarkably affect the freezing performance in the AGF system, while the specific relations between seepage and E remain unclear. Accordingly, this study aims to explore the evolution of frozen wall thickness under seepage conditions via a numerical model that considers the coupled thermo-hydraulic process and variations in hydrothermal properties. As two vital soil properties, spatial variability of thermal conductivity and intrinsic permeability is simulated by random field combined with Monte Carlo simulations (MCs). Based on the coupled model, the effects of seepage velocity, direction, and pipe spacing are examined by sensitivity analysis. Two indicators are introduced to quantify the influences of uncertainty in hydrothermal properties and seepage. The unfavourable scenarios (i.e., lower bound) of E from random models are tabulated and formulated via evolutionary polynomial regression for practical references. These findings contribute to an enhanced understanding of the freezing behaviours of AGF and provide a rule of thumb for predicting frozen wall thickness under complex seepage conditions and design parameters.

Analysis of temperature stress and critical heating temperature for hydronic airport pavement

The hydronic heated pavement system has been widely used for snow and ice removal in airports and other transportation infrastructure facilities because of its good snow melting efficiency and environment friendliness. However, the study of the temperature stress distribution in hydronic pavement and the corresponding critical operation method shows many insufficiencies, which allows security problems during system operation. This paper investigated the temperature stress of the hydronic pavement near the pipes with a 3D finite element model. This model was validated by the measured temperature stress in a full-scale hydronic snow melting experiment system. The locations of the maximum compressive and the time-varying tensile stress in the hydronic pavement were reported. The maximum temperature stresses of the hydronic pavement with various design and operation parameters were compared, and the sensitive parameters were proposed. In particular, the critical fluid temperature with various design and weather parameters was presented by comparing the maximum temperature stress in the pavement with the failure strength of concrete material. The findings show the maximum compressive stress appears near the hydronic pipe, and the maximum tensile stress appears at the midpoint between two adjacent pipes after heating for 2 h. Maximum tensile stress increases with pipe embedded depth, pipe diameter, fluid temperature, and pavement capacity, but decreases with air temperature and pipe spacing. To ensure the safety of hydronic pavement, the critical fluid temperature under different conditions is controlled within the range from 38 °C to 77 °C.

Advancements in design of radiant floor heating systems with an innovative simplified calculation method

The calculation accuracy of existing simplified methods for radiant floor heating systems (RFHS) is far from meeting the growing demand for energy saving. Therefore, an innovative steady-state simplified method is proposed based on conduction shape factors, equivalent thickness, and mirror principle. The new model is validated by experimental data and compared with an equally simple simplified method. Meanwhile, the effects of the total heat-transfer coefficient of radiant surfaces and fluid flow rate in heating pipes on the calculated results are discussed. The calculation flowchart is given. Parameter influence and sensitivity analysis are then performed. The results show that the new simplified model agrees well with experimental data, and the maximum relative error is 7.9% for heat flux and 2.0% for surface temperature. Standard deviation reduces by 68.5% and 66.8% for the heat flux and surface temperature, respectively, compared to the equally simple existing simplified method. With the same absolute increment of pipe pitch, the smaller the pipe spacing, the faster is the heat flux and surface temperature change. The order of importance of influential parameters is mean water temperature > indoor air temperature > pipe pitch > thermal conductivity of filling layer > thermal conductivity of pipe wall.

Model test study on the formation of basin-shaped freezing range in sandy gravel stratum under seepage conditions

The basin-shaped freezing method has a wide range of engineering application prospects because it is environmentally friendly and not sensitive to the depth of the phreatic layer. Based on the similarity theory, multiple sets of model tests were performed to study the development of the basin-shaped freezing range and analyse the influence of seepage velocity, the distance between the freeze pipes and the refrigerant temperature. The test results revealed that, under the influence of group pipe effect, the cooling rate in the middle of the basin bottom was the fastest, and the formation time was the shortest. A single factor had no noticeable impact on the formation time of the closed basin bottom. However, the formation speed of the top surface of basin wall was the slowest under the influence of boundary effect and was significantly influenced by various factors. When the basin wall freeze pipes were arranged with the same spacing along and perpendicular to the water flow direction, the formation time of the top surface of the basin wall perpendicular to the water flow direction was the longest. When the spacing of the freeze pipes along the water flow direction was greater than that perpendicular to the water flow direction, attention should be given to the temperature of the top surface of the basin wall in both directions. The empirical relationships between the formation time of the basin wall and the distance between freeze pipes and the seepage velocity were obtained through regression analysis.

A computational model of an air-layer radiant cooling panel for optimizing and design

Radiant cooling systems have become a research hotspot in recent years. The air-layer radiant cooling panel always had good performance, but there is relatively little research on it. This paper aims to optimize an air-layer radiant cooling panel by establishing a computational model and analyzing its accuracy through experiments. Through the computational model, the effects of surface emissivity, the thickness of the air layer and high thermal resistance material, pipe spacing on the heat transfer performance of the air-layer radiating cooling panel, and the corresponding optimizations have been studied in this paper. Based on the results, it is recommended that a pipe spacing of between 0.1 m and 0.25 m can achieve higher cooling capacity and lower initial costs. The thinner the thickness of the air layer and decorative layer, the better the heat transfer performance. High emissivity materials need to be used on the surface of the air-layer radiant cooling panel to enhance radiant heat transfer. In the process of analyzing the spacing between pipes, a method for calculating the large temperature difference of the fluid has been added, which can help us estimate the cooling capacity in practical engineering, balance initial costs and cooling capacity, and better meet cooling needs.

Thermal performance of phase change material based heat exchanger filled with inorganic salt/expanded graphite

Solid-liquid latent heat storage, featured by the high-density energy storage capacity, is promising in facilitating the high-penetration renewable energy. However, the design of the heat exchanger is challenging due to the conflicting objectives between the heat transfer efficiency and energy storage capacity. To this end, this paper introduces a comprehensive evaluation index, based on which an orthogonal based design optimization method is proposed for heat exchangers filled with inorganic salt/expanded graphite composite phase change material (CPCM). A thermophysical properties based numerical model is built to describe and analyze the solidification and melting of CPCM. The comprehensive evaluation index is utilized to quantify the overall change in heat storage/release performance relative to the mass change of the baseline phase change heat exchanger. The orthogonal experimental method is employed to investigate the impact of various heat exchanger structural factors on the comprehensive performance, followed by optimization design. Simulation results indicated that the longitudinally finned heat exchanger outperforms the other two heat exchangers in terms of the comprehensive evaluation index. Moreover, the inlet fluid temperature exerts a more significant impact on the comprehensive evaluation index compared to the inlet fluid velocity. Additionally, the effects of pipe spacing, fin number, fin height, and tube material on the thermal performance of the longitudinally finned heat exchanger were examined and analyzed. Among these factors, the fin height was identified as the most substantial contribution to the heat transfer performance, while the tube material has a minor effect.

Deformation mechanism and limit support pressure of cutting steel plate during connection between pipes in large spacing using pipe curtain structure method

The pipe curtain structure method (PSM) is a novel construction method to control ground deformation strictly. Compared with the traditional pipe-roofing and pipe jacking method, the connection between pipes in large spacings using PSM is widely acknowledged as a unique construction procedure. Further study on this connection procedure is needed to resolve similar cases in that the pipes are inevitably constructed on both sides of existing piles. Cutting the steel plate during the connection procedure is the first step, which is crucial to control the safety and stability of the surrounding environment and existing structures. The deformation mechanism and limit support pressure of the cutting steel plate during the connection between pipes in large spacings are studied in this paper, relying on the undercrossing Yifeng gate tower project of Jianning West Road River Crossing Channel in Nanjing, China. A modified 3D wedge-prism failure model is proposed using the 3D discrete element method. Combined with Terzaghi loose earth pressure theory and the limit equilibrium theory, the analytical solutions for the limit support pressure of the excavation face of the cutting steel plate are derived. The modified 3D wedge-prism failure model and corresponding analytical solutions are categorised into two cases: (a) unilateral cutting scheme, and (b) bilateral cutting scheme. The analytical solutions for the two cases are verified from the numerical simulation and in-situ data and compared with the previous solutions. The comparative analysis between the unilateral and bilateral cutting schemes indicates that the bilateral cutting scheme can be adopted as a priority. The bilateral cutting scheme saves more time and induces less ground deformation than the unilateral one due to the resistance generated from the superimposed wedge. In addition, the parametric sensitivity analysis is carried out using an orthogonal experimental design. The main influencing factors arranged from high to low are the pipe spacing, the cutting size, and the pipe burial depth. The ground deformation increases with the increased cutting size and pipe spacing. The pipe burial depth slightly affects the ground deformation if the other two factors are minor. Cutting steel plates in small sizes, excavating soil under low disturbance, and supporting pipes for high frequency can effectively reduce the ground surface subsidence.

Analytical and experimental analyses on cooling performances of radiative SkyCool radiators with various interior flowing channels

This study presents an analytical model for the radiative SkyCool radiators (RSCR) with various interior flowing channels by using Laplace transformations. Moreover, the convolution theory is applied to solve the problem of nonuniform temperature distribution on the RSCR. Then, an outdoor experiment is carried out to verify the proposed model. Subsequently, the influence of different channel geometries, flow rates, tilt angles and wind velocities on the cooling performances of RSCRs are investigated. The results indicate that increasing the RSCR's length, enlarging the pipe spacing, and decreasing the flow rate and thickness of RSCR can definitely intensify the cooling performances. The application suggestions for S-channel RSCR (SRSCR) and I-channel RSCR (IRSCR) are given. When the pipe spacing ratio is smaller than five, the IRSCR is recommended because of lower thermal interferences. By contrast, SRSCR is recommended once the dimensionless pipe spacing is greater than ten. For cases with smaller tilt angles but larger wind velocities, IRSCR is suggested, while SRSCR is prioritized for cases with opposite conditions. This research provides an effective analytical tool in the evaluation of cooling power generation by producing cold water, contributing valuable insights for the optimization of cooling efficiencies of RSCRs under varied configuration scenarios.

Research on the Optimization of a Diesel Engine Intercooler Structure Based on Numerical Simulation

As a device for cooling charged air before it enters the cylinder, the intercooler is an indispensable part of the regular operation of a booster diesel engine. To solve the problem of the insufficient cooling performance of an intercooler for a high-power supercharged diesel engine, in this study, the flow field in the intercooler is simulated using the computational fluid dynamics (CFD) model of porous media, and the performance data measured using the steady flow test bench are used to provide boundary conditions for the calculation. The effects of the charged air mass flow rate and the tube bundle’s transverse spacing on the heat dissipation performance of the intercooler are analyzed and compared. The calculation results show that, under the condition of satisfying the regular operation of the diesel engine, the heat transfer coefficient of the intercooler heat dissipation belt increases with the increase in air mass flow and the spacing of cooling pipes, and the heat transfer coefficient can be increased by up to 57%. Still, excessive spacing of the cooling water pipes increases pressure loss in the charged air. Finally, the transverse spacing of the tube bundle is set to 17 mm, ensuring the pressure drop in the charged air, and the heat dissipation performance of the intercooler is increased by 6.04%. This paper provides a feasible solution for further optimizing the heat dissipation performance of intercoolers. Finally, grey correlation theory is used to study the correlation between air mass flow, cooling water pipe spacing, and intercooler heat dissipation performance. The correlation values are 0.8464 and 0.8497, respectively, indicating a significant relationship between air mass flow, cooling water pipe spacing, and intercooler heat dissipation performance.

Numerical Simulation of Heat Transfer Characteristics of Capillary Radiant Heating Floor

In order to study the temperature transference characteristics of capillary radiant heating ground, a glowing temperature change flooring model is typically established to analyze the influence of different factors on the heat transfer characteristics of the heating system. The results show that the distribution of covering temperature is uneven in the radiant heating system, and the fluctuation amplitude increases with the increase of the pipe spacing. At the same time, the change of the surface temperature is further analyzed for the finishing layer material on the radiant heating storey. The results show that the change of the capillary tube spacing leads to a smaller change in the floor exterior temperature when the wood floor is used as the finishing layer. It accurately indicates that the wood floor as the finishing layer can allegedly provide a more balanced surface temperature. Finally, the effects of finishing the layer, filling layer material and pipe spacing are studied for the change of surface heat flux. The results show that the heating effect of 30°C quandary in capillary radiant heating system can merely reach that of 40°C hot water in heating structure with traditional pipe breadth when the finishing layer universally adopts floor tiles and the capillary pipe diameter is 10 mm. This suggests that the thin system can use low-temperature hot water for effective energy-saving heating. The above research results can thoughtfully provide theoretical guidance for radiant floor heating.

Adaptation and Evaluation of Micro Rain Pipe for Small Scale Irrigation

Micro rain pipe irrigation is a hopeful result for effective water utilization and improved crop yields at a lower cost compared to traditional irrigation systems. Technology adaptation was carried out to evaluate the hydraulic performance of rain pipes with different rain pipe spacing (3 and 4) m and hole spacing of (10, 20 and 30) cm using a 3inch pump having 5 Hp system. Hydraulic performance indicators such as uniformity coefficient, distribution uniformity, mean application rate, discharge per hole, coefficient of variation and width coverage were measured. The highest uniformity coefficient of (91.23%), distribution uniformity (84.93%) and mean application rate (17.17mm/h) were recorded under 3 m and 20 cm rain pipe and hole pipe spacing. The maximum width coverage of 6.25 m by one rain pipe was measured at 30 cm hole space under 3 m spacing of rain pipe but it was at nearest with the values of 20 cm hole space of rain pipe with 5.82 m. The results of evaluation indicated that, the appropriateness of rain pipe irrigation as economical and effective alternative for water management in lower space crops. Therefore, the findings of this study indicates that farmers can enhance water use efficiency and improve crop productivity in water scarce area at 1kg/cm 2 operating pressure under 3 m and 20 cm rain pipe and hole space respectively.

Heat exchange characteristics of underground and pavement buried pipes for bridge deck heating conditions.

Geothermal energy is increasingly employed across diverse applications, with bridge deck snow melting emerging as a notable utilization scenario. In Jinan city, China, a project is underway to utilize ground source heat pumps (GSHPS) for heating bridges. However, essential operational parameters, including fluid medium, temperature, and heat exchange details, are currently lacking. This study addresses the thermal design challenges associated with ground heat exchangers (GHE) for bridge heating through a combination of numerical modeling and field experiments. Utilizing software Fluent, a refined three-dimensional multi-condition heat transfer numerical analysis was carried out. Field tests based on actual operating conditions were also conducted and the design parameters were verified. The results indicate that an inlet temperature of 5°C and an aqueous solution of ethylene glycol with a mass concentration of 35% as the heat exchange medium are suitable for the GSHPS in Jinan; Moreover, the influence of backfill material and operation time on the heat transfer efficiency was revealed and the suitable material with 10% bentonite and 90% SiO2 was suggested; Finally, based on the influence of the pipe spacing on the heating characteristics of bridge deck, the transition spacing of 0.2 m is given for the temperature response of the bridge deck. This comprehensive study contributes valuable insights through simulation and experimental analysis of the thermal environment variation, aiming to advance the development of GSHPS for bridge deck heating in Jinan, China.

Phase transition cooling structure towards the wing antenna of hypersonic vehicle

In order to optimize the heat dissipation efficiency of the wing antenna of a hypersonic vehicle, a comprehensive performance-based investigation of active cooling of the wing antenna unit is proposed, taking into account multiple factors. The volume of fluid (VOF) model is employed to simulate and examine the behavior of bubbles and thermal performance on the model surface with respect to the pipe inlet, pipe outlet, and pipe spacing. Furthermore, the heat dissipation efficiency of the wing antenna structure is validated using a quartz lamp as the heat source. The comprehensive performance factor is able to balance the relationship between pressure drop and heat transfer. The simulated heat dissipation efficiency shows a high level of agreement with experimental testing. These results indicate that an appropriate coolant flow rate and flux can effectively provide the degree of phase change, and vapor can only provide effective heat dissipation within a suitable range. Conversely, in situations with excessive or insufficient bubbles, heat cannot be effectively dissipated, thereby reducing the heat dissipation efficiency.

Influence of pore structure on steam disinfection heat and mass transfer in Yunnan red loam

The obstacles to the continuous cropping of Chinese herbs in Yunnan have become increasingly prominent. Many soil-borne diseases can infect the roots of crops, affect the growth of crops, and eventually lead to quality and yield reduction. Soil steam disinfection can still be used as one of the first methods to solve the problem of continuous cropping obstacles of Chinese herbs such as Panax notoginseng. However, the steam will condense into a large amount of liquid water when it is cold, which will cause soil pore blockage and seriously affect the steam diffusion efficiency. Therefore, it is necessary to study the influence mechanism of the pore structure of Yunnan red loam on heat and mass transfer of steam disinfection. The experimental research was conducted on steam disinfection's heat and mass transfer patterns under different soil pore structure conditions. Image processing technology was used to collect accurate soil profiles and to establish real soil pore structure analysis. Then, fluid simulation technology was used to simulate the heat and mass transfer process and trend of steam distribution within the soil profile under different soil pore structures. The results showed that the steam heat flow of <2 mm, 2–4 mm and 4–6 mm treatments were uniformly diffused in the form of matrix flow in a 1/4 ellipse, and the effective disinfection range was 18 cm horizontal distance and 20 cm vertical distance, in which the highest temperature could reach more than 90 °C. The steam heat flow of the 6–8 mm and >8 mm treatment groups diffused irregularly in large pore steam flow. Therefore, some devices for breaking soil and rotary tillage need to finely rotate the soil in the future. The end effector's disinfection pipe spacing can refer to the effective disinfection range.