Thermal Conductivity in Textile Materials: Transient Plane Source Method Vs Steady State Method
Introduction
The Modified Transient Plane Source Method (MTPS) and Steady State Method (HFM) are two popular methods for measuring the thermal conductivity of textile materials. MTPS is faster and more convenient, while HFM is more traditional. When testing a non-woven fabric such as polyester felt, only a slight difference in thermal conductivity values was observed between the two methods.
Scope
The article compares two primary methods used to assess textiles’ thermal conductivity, MTPS and Steady State (HFM). It explains the principles and procedures and what differs between the two methods, referencing the application in testing polyester felt as a non-woven fabric. Upon that, the standards governing these methods, D7984 and ASTM C518-between the advantages and limitations of each one regarding the testing time, accuracy, and requirements placed upon samples are presented. This will enable textile researchers and manufacturers to choose the appropriate technique for their thermal conductivity tests.
Deeper Insights on ASTM D7984 and ASTM C518
Measuring the thermal conductivity of textile materials is an essential factor in assessing their insulation properties. The most common methods are the Modified Transient Plane Source Method (ASTM D7984) and the Steady State Method (ASTM C518). Both methods offer reliable results, but there are essential differences between them.
Modified Transient Plane Source Method
The Modified Transient Plane Source Method (MTPS) is relatively new and increasingly popular with textile researchers. This method obtains thermal conductivity values by applying heat to a material and measuring the heat transfer rate. The time to complete this process is much shorter than that of the Steady State Method. In addition, the MTPS can be used to measure the thickness of the material being tested, eliminating the need for a separate device.
Steady State Method
The Steady State Method is the more classical technique, measuring heat flow through the material using two plates. This method is typically slower than the MTPS, as it takes longer to complete its measurements. The Steady State Method requires a larger sample size than the MTPS. Therefore, if there is an adequate supply of material, this can often be a problem.
When testing a non-woven fabric such as polyester felt, the thermal conductivity values obtained by both methods were very similar, with only about a 1.7% difference. This demonstrates the accuracy and reliability of both methods. While the Steady State Method is more commonly used, the Modified Transient Plane Source Method offers advantages in the testing speed and the ability to measure material thickness.
Difference between the Modified Transient Plane Source Method and Steady State Method
The differences between the Modified Transient Plane Source Method and the Steady State Method are as follows:
| Modified Transient Plane Source | Steady State Method |
| It measures the heat transfer rate from a planar heat source. | It measures heat flow through the material between two plates. |
| It follows the ASTM D7984 standard. | It follows the ASTM C518 standard. |
| Faster; measurements are completed in minutes. | Slower; requires more time to reach thermal equilibrium. |
| It measures material thickness directly. | It requires separate measurements of thickness. |
Conclusion
In summary, MTPS and HFM are efficient methods for determining the thermal conductivity of textiles. MTPS enables quicker and more versatile measuring capability with an added convenience for determining material thickness. This is especially useful in research settings where time is critical. Instead, the Steady State Method remains a standard for industrial use, especially when higher samples and testing times are tolerated. That little difference in results for polyester underscores the reliability of both methods in allowing textile professionals to select the best approach for their needs, resources, and the specification details of the testing to be performed.
FAQs
What is the Modified Transient Plane Source (MTPS) method? The MTPS method is a relatively fast technique for measuring thermal conductivity. It involves applying heat to a material and measuring the heat transfer rate and is especially useful in research settings.
Why thermal conductivity is essential in textiles? Thermal conductivity measures how well a material can conduct heat. Understanding a fabric's insulation properties is crucial in textiles, as these affect applications like clothing, bedding, and industrial insulation.
What is the Steady State Method (HFM)? Steady State Method, or Heat Flow Method (HFM). This technique measures heat flow across a material placed between two plates. Although it takes longer, it is one of the most widely used and well-established techniques for ascertaining thermal conductivity
Which method is more commonly used in industrial applications? Traditionally, the Steady State Method is more frequent in industrial practice due to established reliability, mainly when larger samples and more extended testing times are feasible.
What industries benefit most from these thermal conductivity tests? Industries like apparel, automotive, aerospace, construction, and home furnishings benefit from these tests to optimize insulation and comfort properties.
