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Turbulent flow and heat transfer in an annular geometry have been previously studied experimentally or numerically. Velocity and temperature profiles have been measured and correlations for the wall shear stress and heat transfer have been derived. However there exists no study in turbulent flow for a semi annular geometry. This work aims to study steady and transient convection in a semi annular test section for a wide range of Reynolds numbers from 10,000 to 60,000, the inner cylinder being heated by Joule effect. The velocity profile in the symmetry plane is measured by Particle Image Velocimetry and the temperature of the inner heated cylinder is measured by infrared thermography. The experimental re sults are complemented by numerical simulations which give also access to the velocity and temperature profiles in the whole test section.These results are compared to those obtained in an annular geometry for the same inner and outer cylinders radii and an equivalent flow rate. The velocity and temperature profiles and the wall shear stress are the same as in an annular section in an angular sector of p/2 around the symmetry plane. Both velocity and temperature profiles follow a logarithmic law. In steady convection, the local heat transfer has been characterized in several azimuthal positions. The local Nusselt number can be expressed versus a Reynolds number based on the local friction velocity. Characteristic thermal boundary layer thicknesses are also defined. Finally, transient convection tests are performed with a square power generation. The wall heat transfer and the evolution of the liquid temperature near the wall have the same self similar evolution, with a characteristic time scale, which only depends on the flow Reynolds number.

Active cooling of thermoelectric generators (TEGs) is problematic since mechanical devices such as pumps and fans draw a high proportion of the limited power generated. Increasing the coolant fluid flow rate is typically a scenario of diminishing gains since the increased TEG power can be more than offset by the increase in power required for the fluid mover. Passive air cooling is an option, however the high air-side thermal resistance results in poor TEG power performance and low thermal efficiency. To address these issues, and others, a passive single phase liquid thermosyphon cooling system for use with TEGs has been designed, computationally simulated and experimentally tested. The novelty of the cooling system centres not only on the hot-side heat exchanger design, but also on the use of an open liquid reservoir as a dual-purposed heat store and air-side heat sink. This results in an effective source-to-sink heat exchange system that is entirely passive while providing effective cooling. This work describes the Simulation-Driven Design approach used to design the system for an example of a single TEG, experimental verification of the simulation results and TEG performance characteristics with the new cooling system.