Study On Evaluation Prediction And Regulation Of Temperature Sensation Of Wooden Tabletop

Furniture as an essential appliance in human life,the human body in contact with furniture,the sense of touch is the most intuitive feeling.And the sense of temperature is a very important link in the sense of touch.The thermal comfort of furniture largely affects the sense of use of furniture and affects people’s work and study and even their physical and mental health.Most of the existing research on thermal comfort of furniture is based on subjective evaluation.There is no objective and systematic evaluation system for the long-term contact temperature sensation,and there is no design method for reference.The purpose of this paper is to investigate the principle of temperature perception change after human contact with wooden table tops through the study of systematic temperature perception method.This paper aims to analyze the factors that affect warmth perception,and improve the warmth perception through material design.The main research is divided into the following three parts:the construction of a method for evaluating the warmth perception of wooden desktops;the construction of a model for predicting the warmth perception of wooden desktops;and the study of the regulation of the warmth perception of wooden desktops.The main research results are as follows.(1)The curve of temperature perception evaluation PMV with time was obtained by subjective method of questionnaire survey on the thermal comfort of human body after contacting the material.The temperature perception evaluation criteria were established according to the temperature perception change law.The local thermal comfort during long-term contact with the material can be measured by the temperature perception comfort time weight P,which is the weight of the duration of temperature perception comfort to the total contact time.According to the size of P value to different materials temperature sensation is divided into eight levels,the larger the number the more uncomfortable.The temperature change after human contact with the material was measured by the human body method,and the linear regression equation of PMV on Th and Ta was obtained by linear regression analysis between the value of PMV obtained by the subjective method and the average human contact temperature Th obtained by the objective method.Based on this,a device that can replace the human body for heat release was developed independently,and the temperature sensory change was studied by the device simulation method.(2)The finite element simulations were performed using the solid heat transfer module of the COMSOL simulation software,which treats the human upper extremity as a constant temperature fixed heat transfer heat source for transient heat transfer simulations.The finite element simulations provide a good curve fit and have few constraints.Through the finite element simulation of the wooden desktop material simulation found that the density,heat capacity,thermal conductivity,room temperature of the material not surface decorated presents the same trend,temperature sensing is with the increase in value showing the phenomenon of first rise and then decline.For the surface decoration of the wooden desktop material,the density and heat capacity of the surface decoration material has little effect on the temperature sensation,which can be neglected.(3)Combined with COMSOL finite element simulation software and MATLAB data processing software to build a predictive model of wood desktop temperature sensing.And on the basis of the prediction model,a temperature-sensitive design system was constructed for the wooden desktop.The first single factor analysis found that the six influencing factors substrate thermal conductivity,substrate density,substrate specific heat capacity,substrate thickness, surface decoration thickness,and surface decoration thermal conductivity will have an effect on the temperature perception of the wooden desktop.The optimal thermal comfort will increase with the level of the influencing factors base shows a trend of first increase and then decrease.The multivariate linear regression equation R~2=0.858(R value is the correlation coefficient) obtained after 5 levels of central composite design for the six influencing factors,the equation has a good fit.On the influence of optimal thermal comfort time,the influence of thermal conductivity of substrate on temperature perception is the largest,much larger than other factors,and the influence of surface decoration thickness on temperature perception is the smallest.After the central composite design,the thermal conductivity of wood desktop material substrate 0.224W/(m·℃),substrate density 792.546 kg/m~3,substrate specific heat capacity 1463.43 J/(kg·℃),substrate thickness 24.531 mm,surface decoration thickness 0.247mm,surface decoration thermal conductivity 0.047 W/(m·℃),wood desktop temperature awareness to reach the best value.(4)After design practice with the Wooden Desktop Thermo-awareness Design System,it was found that it was difficult to achieve better thermo-awareness levels at higher room temperatures under restrictive conditions.By adding phase change microcapsules(PCM)to the paint film,the thermo-awareness can be adjusted.However,PCM is difficult to disperse in waterborne coatings,so terpolymer hyperdispersant SSS-MPEGA-MA(SMM)was synthesized for the dispersion of PCM in paint films,which has good dispersion effect for PCM slurry with20%solid content,and the optimal amount is 2%of PCM content.After adding PCM powder into water-based paint,the hyperdispersant was added to make a temperature-aware regulated coating.Through the self-developed heat transfer simulation device,the dispersion effect,paint film properties and thermo-awareness properties were integrated,and it was found that adding two top coats on the 10%solids PCM primer was more effective.