Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.
Room temperature compressed air was pumped into a short (H/D = 0.18) vortex chamber. Experiments revealed temperature separation. The highest temperature of the periphery was 465 C, and the lowest temperature of the central zone was -45 C. During the process, heat was transferred to periphery in the opposite direction of the powerful vortex flow. This heat transfer cannot be explained by conventional heat transfer processes. To explain this phenomenon, the concept of Pressure Gradient Waves (PGW) is proposed in the paper. PGW are elastic waves which operate in compressible fluids with pressure gradients and density fluctuations.