The ultimate objective of this research is to investigate the effectiveness of cathode gas (air) recirculation for the thermal management of a solid oxide fuel cell (SOFC) stack. SOFCs conventionally operate at high temperatures (>600o C); and recovering heat from stack exhaust is critical to improving the stack and system performance. Prevalent approaches implement bulky and expensive high temperature gas-to-gas heat exchangers. Also, ejectors are being investigated for recirculation of the air; however, an ejector with typically large velocity gradients would incur large viscous losses. An alternative recirculation approach is being developed for distributed entrainment via active flow control. The entrainment would allow recuperative thermal mixing to occur that may be more effective than the preceding two approaches. The ultimate goal of this research thrust is to reduce, or even exclude, the need of an air preheater in a SOFC system. The cathode air preheat contributes to a large portion of the cost of a SOFC system. Verifying and demonstrating the efficacy of the Coand and #259; effect has been the initial focus, and positive results have been demonstrated in a test environment from a fluid mechanics standpoint. This has been based upon three stages of experimental development, inclusive of cross-sectional area and activated blowing degrees-of-freedom. Seed thermal testing of the system has demonstrated legitimate thermal mixing capabilities. EES thermodynamic modeling developments confirm that the approach can reduce or even exclude the air preheat. It is concluded that recuperative thermal mixing with this recirculation approach is indeed feasible and has the potential to greatly reduce the cost and efficiency of the SOFC system.

This thesis deals with regenerative heat exchangers and their operational issues. The theoretical part explains rotary and fixed bed regenerators. Further it includes the most common issues we encounter in operation. Practical part presents a design of rotary regenerator which cools flue gas from wood chip boiler. Calculation contains stechiometry of flue gas and air, design of rotor, calculation of outlet temperatures, strength calculation, dynamic calculation and design of heat exchanger peripherals.

The thesis is focused on structural design of unconventional experimental combustion air preheater into drawing documentation needed for production and realization. Strength and expansion control of exposed elements of construction is also included in the thesis. The final design is obtained by gradual specification of pre-designed and strength and expansion controlled elements of construction. The work also includes discussion of structural properties of the final design.

This master’s thesis is dealing with design of steam boiler for wood chips. Wood chips are considered as biomass and so the steam boiler is considerate to enviroment. Main purpose of this work is calculation of size and number of water/steam heating surfaces so the boiler can produce steam with required parametres of temperature, pressure and amount.

The aim of this Diploma thesis is design of steam boiler with steam reheating, for combustion the blast furnace gas. The fuel composition and primary parameters for calculation of the boiler were provided. In the first part the fuel composition is described. The main part of the thesis consists of stoichiometric calculations, establishing efficiency of the boiler, calculating combustion chamber as well as design and calculation individual heating surfaces. Part of the work is also drawing documentation of boiler.