The development of liquid crystal techniques for temperature and heat transfer coefficient measurement over the past ten years, coupled with image processing, has opened some new approaches for heat transfer research and may lead to important changes in the way research is conducted during the next decade.

The history of these techniques is reviewed and the principal methods are described, using examples from the current literature. Three methods of image interpretation for liquid crystal studies are reviewed, and examples from each are presented.

The present capabilities for detailed experiments by image processing allows experiments to be planned which could not have been contemplated ten years ago, and that opens the door to a possible re-conceptualizing of convective heat transfer to make it easier to deal with situations involving non-uniform heat transfer. The concept of h-adiabatic is introduced and some of its advantages and possibilities are discussed. That approach is attractive, since h-adiabatic is independent of the thermal boundary conditions, reflecting only the geometry, fluid properties, and fluid mechanics of the situation.