cfd-simulation-of-frost-on-horizontal-cold-surfaces

CFD Simulation of Frost on Horizontal Cold Surfaces

Frost formation is a common phenomenon observed across many different fields, including refrigeration, construction, and natural gas processing. However, ...

Shenyang Jianzhu University

Organic phase change material (PCM) with macro-encapsulation is attractive in energy storage applications as it has relatively low cost. This study focuses on using PET plastic pipes to encapsulate paraffin and using low-cost float stones to increase the thermal conductivity of PCM modules as they have a special structure of high porosity. Float stones were immersed in the liquid PCM and an ultrasonic welding method used to prevent leakage of the PET plastic pipes. Scanning electron microscopy (SEM) was used to discover the appearance of the composite PCM. The thermal performance of the PCM cylinder module was analyzed through experimental tests of a constant-temperature water bath and numerical simulations. The result indicates that this PCM Ccylinder module is superior in thermal energy storage compared with the reference module even though fewer PCM was contained and the latent heat loss is considerable. The pipe diameter is an important parameter when using this kind of PCM cylinder module in water tanks.

Macro-Encapsulated PCM Cylinder Module Based on Paraffin and Float Stones.

Predicting influence of human thermal plume on the diffusion of respiration-produced particles is an important issue for improving indoor air quality through eliminating infectious microbes efficiently. In this study, the Large Eddy Simulation was utilized to predict the effects of thermal plume of different intensities on particle diffusion. Three postures of the human body model and three room temperatures were considered. The results show that the convective heat transfer coefficient on the surface of the human body varies greatly with different postures. The coefficient is the largest when the model is in sitting posture, leading to the greatest heat transfer rate. Meanwhile, the thermal plume generated by bending the thigh increases the size of the facial thermal plume in horizon direction. The increase of the difference between indoor temperature and skin temperature causes an increase of the convective heat transfer of the manikin, leading to stronger airflow in front of the face. The thicker and faster the human thermal plume is, the more difficult it is penetrated by aerosols produced by nasal breathing, finally resulting in most particles distributed within 0.2 m thick under the roof.

Study on the motion law of aerosols produced by human respiration under the action of thermal plume of different intensities.

Residents tend to close the doors and windows of their residential kitchens in severe cold conditions, making insufficient outdoor air supply and aggravating indoor air pollution. In order to understand the ventilation and pollution status of the residential kitchens in a severe cold region and improve the ventilation system, this study used questionnaires, on-site tests, and Computational Fluid Dynamics (CFD) simulation to analyze a pollution and ventilation case in Shenyang, China. The method of using ceiling openings to compensate for outdoor air supply was proposed and optimized to improve air distribution in the residential kitchen. The average CO concentration in the breathing region, air velocity, and temperature levels in the kitchen, before and after the improvement, were compared. The results indicated that the kitchen pollution in severe cold area of Shenyang is serious, and the ventilation habit has regional characteristics. Furthermore, the overall kitchen environment including air velocity, temperature, pollutant levels, static pressure, CO concentration, indoor airflow fluctuation, and cooking fire were obviously improved for the ceiling make-up air cases. These findings provide a basis for improving the reasonable air distribution of residential kitchens in cold regions and for building a thermally comfortable environment.: In order to understand the ventilation and pollution status of the residential kitchens in a severe cold region and improve the ventilation system, this study used questionnaires, on-site tests, and Computational Fluid Dynamics (CFD) simulation to analyze one pollution and ventilation case in Shenyang, China. The method of ceiling openings to compensate for outdoor air supply was proposed and optimized to improve air distribution in the residential kitchen. The average CO concentration in the breathing region, air velocity, and temperature levels in the kitchen, both before and after the improvement, were compared. The results indicated that the kitchen's air velocity, temperature, and pollutant levels are much better for the ceiling make-up air case compared with permeation and opening window cases. The static pressure, CO concentration, indoor airflow fluctuation, and cooking fire showed remarkable improvement in the residential kitchens. These findings provide a basis for improving the reasonable air distribution of residential kitchens in cold regions and for building a thermally comfortable environment.

Article	Year
Macro-Encapsulated PCM Cylinder Module Based on Paraffin and Float Stones. Materials (Basel, Switzerland)\| PubMed ID: 28773480	2016
Study on the motion law of aerosols produced by human respiration under the action of thermal plume of different intensities. Sustainable cities and society\| PubMed ID: 32288992	2020
Ventilation status of the residential kitchens in severe cold region and improvement based on simulation: A case of Shenyang, China. Journal of the Air & Waste Management Association (1995)\| PubMed ID: 34727011	2022

Guohui Feng

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