Research On The Instrument And Standard Test Method Of Clothing Thermal Insulation

In the domestic market of autumn and winter clothing,a lot of warm clothing made of new materials were produced every year.However,the evaluation of clothing thermal insulation lacks of a uniform standard,which lead to the proliferation of various false advertisement in clothing market of autumn and winter each year.Clothing thermal resistance is as an important evaluation index of clothing thermal properties,thermal manikin or sweating manikin has been used to test clothing thermal resistance or thermal insulation in the field of research and special professional clothing,but due to lack of uniform standard,single size of test equipment and complex operating methods,test method of thermal manikin is not spread well.LD-1 clothing thermal insulation tester has been jointly developed by Donghua University and Shandong Laizhou Electronic Instrument Co.,Ltd in 2015.So far,it has been developed to the second generation.Three-dimensional shape of equipment is a simplified prosthesis and referred to the three-dimensional structure of clothing and material thermal resistance.Compared to thermal manikin,LD-1 clothing thermal insulation tester has no limbs and head.And the distance between the front and back parts can be changed to adjust the bust to test different size clothing.In this paper,in order to improve the performance of LD-1 clothing thermal insulation tester,and establish the standard test method of clothing thermal resistance.We have completed the following two aspects:1.The main work and conclusions of the test instrument :(1)Analyzing the new thermal manikin developed in recent more than and 10 years at home and abroad,we found that body sectional temperature control region of thermal manikin is divided more and more small,and most manikin can simulate human walking,posture and sweating.In short,the wet and heat dispersion and exercise performance of thermal manikin is more and more like a real person.It is good for the accurate evaluation of the thermal insulation and moisture comfort.But their structure,temperature and sweating system is complicated and expensive.Each manikin can just test only one size of clothing.Compared with the LD-1 clothing thermal insulation tester,the structure of the later is greatly simplified,and can eliminate the obvious influence of special clothing structure on clothing thermal insulation.But the application range of it isn't influenced.Through adjusting the size of chest,LD-1 clothing thermal insulation tester can test a wide range of clothing.(2)Based on the detailed analysis of instrument,calculation methods of thermal resistance at home and abroad and our test data,three suggestions are put forward for the instrument:a.Because the existing national standard resistance formula of thermal manikin in the world are all involved in the clothing area,and caused errors in the measurement of clothing area.We put forward a new definition of garment thermal resistance.the surface of thermal manikin is used to replace the traditional garment surface area in the calculation.It can reduce the errors of clothing area and can directly reflect clothing thermal insulation.b.Taking into account that the thermal resistance calculation formula contains air temperature around instrument.We analyzed the distribution of surrounding air temperature and found that the air temperature around instrument decreasing from the top to the bottom of the law.At the same time,the front surface of the instrument is affected by the air flow,and the air on the back is still.So the air temperature on the back is slightly higher than the positive air temperature.And taking into account that the back test board area is about 1.5 times of the positive test board,it is recommended to install 3 temperature sensors from top to bottom on the back,while 2 temperature sensors from top to bottom in front.The air temperature around the instrument is calculated using the weighted area of the test board.c.The fitness of clothing is one of the important factors that affect the clothing thermal resistance test,and is also the content of this research.As the bust,waist circumference and hip circumference of the prosthesis cannot be controlled separately,the bust is as the key control site to explore the relationship between clothing size and prosthesis chest.According to GB / 1335 standard and the size of the prosthesis when the chest expansion is 1cm,3cm and 5cm,we found that suitable testing garments for LD-1 clothing thermal insulation tester are: Y-type clothing with bust of 96 cm and 100 cm,A-type clothing with bust of 96 cm,100cm and 104 cm,and B-type clothing with bust of 104 cm and C-type clothing with bust of 100 cm.In order to expand the application of the instrument,we add a new way to change the manikin measurements by increasing the chest circumference and hip circumference inhomogeneously.It expand the measuring range of the instrument.Made the instrument can test B-type clothing with bust of 96 cm and 100 cm,C-type clothing with bust of 96 cm.2.The main work and conclusions of the testing method for clothing thermal insulation(1)A series of experiments show that non-steady state heat transfer time of the instrument is influenced by environmental temperature and clothing thermal resistance.The lower the ambient temperature is,the longer the non-steady state heat transfer time is;the greater the thermal resistance,the longer the non-steady state heat transfer time.Therefore,for the thermal resistance of about 1 clo of the spring and autumn clothing,unsteady heat transfer time of 30 min is recommended,and for lower thermal resistance of summer apparel,you can set a shorter heat transfer time of non-steady state,While for the clothing with thermal resistance greater than 1 clo,the unsteady heat transfer time of 30 min is not enough for LD-1 clothing thermal insulation tester,and it is necessary to increase the heat transfer time.For clothing samples which the approximate thermal resistance can be estimated,the required test ambient temperature can be determined by Equation(A)and the unsteady heat transfer time is predicted from Equation(B).(?)(A)(?)(B)Finally test ambient temperature and heat transfer time of the unsteady state are inputted into instrument to start test.However,no matter what kind of specimen,unsteady heat transfer time is checked after test.(2)For the jacket clothing,the true thermal resistance of clothing cannot be got by wearing clothing test with the naked instrument.The tests should be carried out by combination of standard underwear,and the thermal resistance of jacket sample can be obtained by minus the thermal resistance of the underwear from the total thermal resistance.With the test of wearing same jacket by combination of different underwear,the significance tests of the results of wearing different underwear are performed.We have found that wearing different standard underwear has no effect on thermal resistance test results of the jacket.(3)Temperature and humidity are also one of the factors that affect clothing thermal resistance.It is found that the ambient temperature and humidity have no effect on the thermal resistance of the naked body of the instrument,but they have a significant effect on the thermal resistance test value of the garment by carrying out the thermal resistance experiment of naked body in different environments.The thermal resistance test values of garments will increase with the increase of the ambient temperature.But the significant relationship between the clothing thermal resistance and relative humidity cannot be captured in this experiment.The reason is that the range of experimental humidity is relatively small and winter clothing are thicker,so the water vapor pressure difference between inside and outside of clothing is small.However,due to the fact that the moisture absorption capacity of the fiber can cause changes on insulation properties,the impact of the environmental humidity on the clothing resistance test value is inevitable.Therefore,the measurement of clothing insulation should be conducted on the conditions of close to environmental temperature and humidity of the use situation.