Abstract
Electrically heated platinum wires of 0.1 or 0.2mm diameter were longitudinally vibrated in air and water. Heat transfer coefficient obtained at RePr1/3 value ranging from 20 to 300 was expressed by an experimental formula:
Heat transfer coefficient of sewing needles for air derived from the above formula is as follows;where h, N, D and Tm are heat transfer coefficient (kcal/m2h°C), sewing speed (spm), blade diameter (mm) and film temperature (°C) respectively.
The heat transfer coefficient of the blade part of a sewing needle (#16) determined by Newton's cooling law in a previous paper2) agreed well with the result calculated from the above formula.
