Dynamic modelling, experimental validation, and thermo-economic analysis of industrial fire-tube boilers with stagnation point reverse flow combustor

Abstract

Radiators represent the most spread heating body (installed since late 1800s) and in the last decades different radiators typologies have been proposed on the market, characterized by different materials, sizes, shapes, etc. Recent EU Directive on energy efficiency has set the obligation to install individual meters for space heating in building served by a central heating source. To this aim, when direct heat meters are not technically feasible, indirect systems like heat cost allocators are applied on each radiator in a dwelling and the knowledge of single radiators' thermal output is essential for an accurate and fair heat cost sharing. The EN 442:2014 describes a method for radiators' thermal output measurement whose expanded uncertainty is lower than 1% in reference laboratory conditions. However, radiators' thermal output is strongly dependent on installation and boundary conditions. Thus, to get radiators' thermal output at operating conditions "characteristic equations" are available but, unfortunately, they do not include any possible actual operating condition among which: installation position with respect to the wall and the floor, presence of grid/shelf/niche or an obstruction (e. g. caused by curtains), thermo-fluid-dynamic condition variations (inlet flow rate and temperature), and hydraulic connections. In this paper, the experimental results of thermal output measurement of different radiators typologies (cast iron, aluminum) at different installation conditions are presented, together with an analysis of the associate technical-economic effects on space heating cost sharing. Reductions of radiators' thermal output up to 15% due to hydraulic connections and between 10% and 20% due to flow-rate variations have been found. Furthermore, different installation conditions showed deviations between operating and standard radiators' thermal output between 5% and 15%.

Study of Different Alternatives for Dynamic Simulation of a Steam Generator Using MATLAB

“…The two derivatives are averaged to obtain an improved estimate of the slope for the whole interval. Equations ( 10) and (11) shown below are used to solve differential equations with this method.…”

“…It is necessary to know and understand the functioning of these systems. This has been possible through the formulation of mathematical models that represent their behavior with excellent results [6][7][8][9][10][11][12].…”

Heat Transfer and Thermal Efficiency in Oxy-Fuel Retrofit of 0.5 MW Fire Tube Gas Boiler

“…The combustion gases exiting the combustion chamber traverse the fire tube, generating steam. In air combustion, convection predominates in the fire tube, with the design primarily focusing on convective heat transfer [30]. However, in oxy-fuel combustion, radiation's significance becomes pronounced [17], necessitating its consideration.…”

“…During the thermal design of an air combustion boiler, the fire tube's design relies on convective heat transfer [30]. The Dittus-Boelter equation [31], such as Equation ( 5), facilitates the prediction of the convective heat transfer coefficient.…”

Study of PID controller gain for active vibration control using FEM based particle swarm optimization in COMSOL multiphysics

“…Design and development of FEM-based controlled system have drawn the attention of researchers in the past few years. [17][18][19][20] Karagülle et al 21 coupled the proportional controller with FEM analysis to control the vibration of a cantilever beam by the piezoelectric actuator in ANSYS. Similarly, Russ et al 22 integrated the PID controller with FEM analysis for simultaneous vibration suspension and precise positioning of the smart structure in ANSYS.…”