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Solar Engineering Of Thermal Processes

Opportunities and challenges in sustainable treatment and resource reuse of sewage sludge: A review

A Critical Review on Additives to Reduce Ash Related Operation Problems in Biomass Combustion Applications

A distributed activation energy model for the pyrolysis of lignocellulosic biomass

The paper analyzes the effect of small deviation of incident angle relative to the focal plane on thermal performance of parabolic-trough solar collector. Decrease of solar collector thermal output is presented in form of coefficient of performance i.e. function of the incident angle deviation. In solar collector operation mode, working fluid (e.g. water) can become overheated. In that case, decreasing the thermal output would influence temperature drop of working fluid. Rotation of a parabola for a small angle relative to the focal plane will decrease the output thermal power of the solar collector. This analysis contributes to calculate deviation of incident angle relative to the focal plane in order to achieve the given thermal output for defined input parameters — collector type, local and real conditions (i.e. Sun position, orientation, time and date). In this paper, two-dimensional analytic geometry was used as a basic methodology for calculations and simulations.

Effect of small deviation of incident angle on thermal performance of parabolic-trough solar collector

Noise is becoming one of the problems in many industrial applications. In this paper the aerodynamic noise in air duct system that arises from air flow passing over a surface of turning vanes is investigated. Based on Proudman's formula using Lighthill's acoustic analogy broadband acoustic noise model can be predicted. To model the turbulent flow in an air duct k - e turbulent model is used and required constants are obtained experimentally in a low speed wind tunnel followed by noise measurement in the vicinity of deflected airfoil. Several designs are investigated: Inner airfoil in the duct elbow, center positioned air foil, outer positioned and the overall combination of all previous cases. It was found that in order to satisfy all noise requirements and regulation, which are becoming more strict nowadays, the acoustic analysis and design must be performed in most industrial systems since the noise levels arising from the operating industrial equipment may represent occupational and health hazard.

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A study of aerodynamic noise in air duct systems with turning vanes

In this work complete methodology for calculation and analysis of fluid flow in air ducts is presented. In order to minimize outlet pressure drop and to reduce the duct vibrations the plates with airfoil cross sections are added to duct critical zones. It was observed that airfoil stream plates efficiently contribute to outlet pressure drop, duct vibration and noise reduction. Modern methods such as CFD and FEA can be efficiently deployed in numerical treatise of flow and vibration analysis in air ducts.

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Air duct modification towards outlet pressure drop and vibration level reduction

The paper presents a simple mathematical model for designing, optimizing and simulating small–medium CHP scale plant with use of biomass waste downdraft gasification. A downdraft gasifier has been used as the starting point in the study, due to its low tar content and effective way of using heat in the engine’s exhaust gases to dry and pyrolyze the different solid biomass waste. Hot water from the cooling circuit of the engine and from producer gas cooling is directly used for the district heating network, air or steam preheating. The mathematical model includes modelled components as a downdraft gasifier, an internal combustion engine using the characteristic equation approach method. The mathematical model enables the outputs of the plant to be evaluated and calculated for different types of biomass and operating conditions. The results demonstrate that it is a useful tool for assessing the performance of CHP plants using several types of biomass waste and enables comparisons to be made between operating conditions for real applications.

Mathematical Modelling and Performance Analysis of a Small-Scale Combined Heat and Power System Based on Biomass Waste Downdraft Gasification

Constant demand for development and construction improvement of small scale pellet stoves and boilers (nominal power up to 50 kWth) for household heating leads to conclusion that appropriate upgrading should be done on that field. Optimisation of stove construction should be performed based on results of experimental tests, as well as results of numerical analysis and mathematical modelling of combustion process. This is compulsory, because stove construction shall comply with demands for energy and environmental characteristics defined in appropriate quality standards. Besides, stove should operate with pellets of different quality, produced from various biomass raw materials. Considering that numerical analysis is less time consuming process than experimental tests, nowadays it is more often used for development and improvement of combustion appliance construction. As the turbulence modelling is one of the key parts in the eligible numerical analysis, the aim of the research presented in this paper is to define the influence of different k-e turbulence models and their application on defined CFD mathematical model of combustion process in small-scale pellet stove for household heating.

Marta Trninić

Papers

Effect of small deviation of incident angle on thermal performance of parabolic-trough solar collector

A study of aerodynamic noise in air duct systems with turning vanes

Air duct modification towards outlet pressure drop and vibration level reduction

Mathematical Modelling and Performance Analysis of a Small-Scale Combined Heat and Power System Based on Biomass Waste Downdraft Gasification

Application of different k-ε turbulence models on combustion process modelling in small-scale pellet stoves for household heating