Dr. Hertel joined the faculty of the university in 1926 as assistant professor of physics. He served as head of the Physics Department from 1935 to 1956, and as director of the UT Fiber Research Laboratory (a regional laboratory supported by the UT Agricultural Experiment Station [now AgResearch] and the US Department of Agriculture) in 1938–68. In 1934 Hertel was a founder of the UT Research Corporation, and he served as president of the corporation in 1954–69.
As department head Hertel promoted a closer relationship between the Oak Ridge National Laboratory and UT and was instrumental in establishing the Oak Ridge Institute of Nuclear Studies (now Oak Ridge Associated Universities). Hertel invented several instruments for the measurement of cotton fibers, including the fibrograph and the arealometer, which, with improvements and modifications, are still in use today. He held 12 patents and was the author of many professional articles and specifications for the American Society for Testing and Materials. In 1970 he received the Harold DeWitt Smith Award of the American Society for Testing and Materials for outstanding achievement in the science of textile-fiber utilization. His contributions to the intellectual life of the university have been recognized by the placement of a plaque in his honor on a faculty study.