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 project has investigated and formed a basis for the thermal- and flow-induceddynamic loads in the lower parts of a preheater situated in a nuclear power plant.Special attention has been given to the bottom plate that separates the heated andnon-heated secondary steam. Using computational fluid dynamics (CFD), steady RANSsimulations were first used to investigate how the flow into the preheater was affectedby the inlet boundary conditions. From there a steady RANS conjugate heat transfer(CHT) analysis was conducted as to obtain the temperature field within the preheaterand its solid components. This also investigated different approaches in modelling theheat transfer between the primary and secondary steam. Lastly, a scale-resolving LESwas conducted as to obtain the flow-induced dynamic loads on the bottom plate. The results show that the modelling used in previous works gives a less uniformtemperature distribution as compared to when appropriate heat transfer coefficient(HTC) correlations are applied. Regardless of how the heat source is modelled, hot spotswith significantly larger temperatures are present in the bottom plate near the outletsof the bottom tube sections. The root mean square value, amplitude and frequencycontent of the fluctuating force acting on the bottom plate have also been obtained.The results of the analysis provide a good starting point for future work examining ifthe loads on their own or in combination may risk damaging the structure.

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.

This diploma work attends to presentation of steam grid boiler for wood and brown coal burning in scale (30/70-wood) in load 60t/h, with parametres of outgoing vapour p=7MPa, t=490°C. The work is splitted to several chapters. At the beginning I’m going to make stechiometric calculation and entalpic calculations of air and compustion gas. After that I’m going to calculate heat balance, losses of boiler and set heat efficiency of boiler. Then I’m going to suggest combustion chamber of boiler and make heat calculation. After suggestion of combustion chamber I’m going to set proportions of pulls and heat-delivery surface. In last chapter I’m giong to check heat balance. Inclosure of my work contains drawing documentation of steam boiler.

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.

This thesis deals with the influence of balcony glazing to preheat ventilation air. In the first part there are described the ways of passive use of sun radiation and types of ventilation of flats. THESEUS-FE 4.0 is used as a simulation program, for which heat transfer is described. The second part contains description of flat and selected case simulation, followed by a geometric model and description of boundary conditions. Finnaly is done evaluation of case simulations not only in therms of savings in ventilation, but also for heat loss as a whole.

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.