I have been researching about best reference books, best lecture series, and best universities to study thermal sciences since I was in college, and along the way, I have found some good resources that I feel like sharing with everyone because sometimes Google, YouTube and other search engines do not necessarily show these on the first results page when we do the search about these topics
1. Engineering Thermodynamics I ME3293 Fall2015 - Randall Manteufel
Professor Randall has really good teaching skills and he teaches the subject from the industrial applications point of view in mind along with abstract thermodynamics concepts. This approach is really important for students who want to work in industry and do not want to go into academia/research.
2. Heat Transfer (2015): Dr. John Biddle's Lecture Series - Dr. John Biddle
This lecture series on heat transfer comes from a really cool professor who has taught the subject for the last 40 years (and still does). Good explanation and demonstrations along with practical real-life examples and numerical solving techniques. His lectures on convection heat transfer and how to identify the problem type are illuminating.
3. Heat Transfer Lectures (2019) by Prof Josua Meyer - Josua Meyer
Josua Meyer is the most accomplished researcher when it comes to scientific research in the area of heat and mass transfer. He has published around 671 papers in all highly sought-after journals. His lectures on conduction and convection heat transfer are very easy to understand.
Fluid Mechanics is a very complex subject and only theory is not enough to understand the phenomenon in the fluids. This lecture series from the National Committee for Fluid Mechanics explains many complex phenomena in FM through experiments. It is at least 50 year old series hence do not expect high-quality video. But the content is high quality for sure. Link to PDF of the above lectures
5. ME3663 Fluid Mechanics Summer2016 - Randall Manteufel
If you like Professor Randall Manteufel's teaching style then you will love this lecture series on Fluid Mechanics too.
6. Fluid Mechanics I - Dr. Biddle's lecture series - Dr. John Biddle
If you like Professor John Biddle's teaching style then you will love this lecture series on Fluid Mechanics too.
7. Thermodynamics Forum Last but not the least :)
Thermodynamics forum has a repository of almost all types of numerical questions and their answers related to thermal sciences. It has a vibrant community that helps each other by posting questions and discussing various topics in the field. It also has conceptual/informative Q&A-type posts.