Search

The ever-increasing demand on highly efficient decentralized power generation with low CO2 emission has made microturbines for power generation in micro-combined heat and power (mCHP) generation systems popular when running on biofuels as a renewable source of energy. This document presents a state-of-the-art design, and optimization (in terms of design, performance and emission control) of a micro-turbine renewable energy combustor that fits into the existing Bladon 12kWe recuperated microturbine plenum while running on a range of biofuels as it can successfully provide the required power of the mCHP. Governing equations for in-depth analysis of the combustor consist of manufacturer empirical data to simulate system-level operation with respect to replacement of the fossil with biofuels. The Model developed and validated at company’s ISO conditions confirms the output power of the new combustor fits the conventional system with slight eco-energy improvements. The modeling of the combustor in a complete microturbine assembly system is performed, then was utilized to further analysis of the microturbine with the designed combustor. The experimental results gave on average 46.7% electrical efficiency, 83.2% system efficiency, 12 kWe electrical power, and 90% recuperator effectiveness at nominal operating conditions of microturbine (MT). Sensitivity analyses evaluate changes in performance with respect to fuel phase (e.g., liquid or gaseous) and design variables (e.g., orientation, shape, and dimensions of combustor), leading to energy optimization of the unit. Experimental findings demonstrate that the combustor in microturbine can meet the target performance specifications of a company conventional diesel microturbine with significant savings. An objective function including both combustor and recuperator technical energy data is defined for finding the best ratio of fuel and air and their flow rates to find the most effective operating points for the operation of MT. Annual time series simulations completed for Coventry, West Midlands, United Kingdom indicate a new combustor can reduce operational costs of diesel fuel combustor by 8%, 2%, 36%, and 25% when supplying bioethanol, DME, biogas, and NG, respectively. Annual operating time of the renewable microturbine combustor at rated capacity included an 11% reduction in exergy loss with biogas fuel relative to diesel fuel.

One of the effective strategies in meso and micro combustors for flame stabilization is to consider a wall cavity in a step. This extends the blow-off limit that can cause flame stagnation and anchoring. In the present work, the premixed hydrogen turbulent flame in a photovoltaic combustor with a step is simulated, validated and researched in terms of flame stabilization at different operating points including jet temperature, velocity, hydrogen, nitrogen, water content, and equivalence ratios. The effect of preferential transport of species is also evaluated and discussed. The results of simulations were employed to investigate the flame anchoring by showing the interplay between the flow field, heat recirculation, elementary reactions, transport of species. The results confirm that in this combustor the fresh reactant is gradually heated by the channel walls. This shifts the threshold of the combustion to the vicinity of the microchannel interior walls and more intense combustion downstream. The combustion in partially reacted materials is intensified by passing the duct interior walls when it faces the recirculating materials in the channel cavity leading to flame anchoring and stabilization from the cavity wall. The flame anchoring mechanism in this channel is the heat recirculation via channel walls, recirculating materials, and radical pool in the channel cavity for premixed hydrogen/oxygen flame. The effect of heat recirculation is found dominant in flame anchoring as in most case studies the flame stabilizes and evolves from the duct interior walls. The heat transferred to fresh reactant was 140, 129, 127, and 77 kW/m2 in Inconel, Stainless Steel, Silicon Carbide, and Quartz combustor, respectively.