Fog unit (IFUS)

IFUS: Individual Heat Supply with Integrated Fog Unit System

Project IFUS offer new technological solution of flue gas purification for small capacity biomass boilers, which is intended to reduce emissions and improve energy efficiency (till 20%), comparing with traditional solutions. The main idea for this solution is to create fog effect zone in the equipment of flue gas purification, thereby reducing emissions of small particles (PM 10, PM 2.5) and environmentally harmful gases. Fog zone properties in the joint of pollution will be considered also using electric and electromagnetic field. The main project activities include the creation of experiment plan for the process research of heat and mass exchange in the experimental equipment, the creation of mathematical model and coincidences comparison of the results with experimental data, measurements for determination of emissions reduction and energy efficiency improvement, using experimental equipment. Identification of technological solution will be done for pH level regulation during flue gas purification, to prevent risks of corrosion, and purification of pulp, which has emerge during flue gas purification. Finally process analysis of influencing parameters will be carried out, to be possible to improve performance of equipment. Main project result – prototype will be developed for equipment of flue gas purification, which is for emission reduction of small capacity boilers. The project aim is to develop new equipment solution of flue gas purification for combustion equipment of small capacity boilers, reducing emissions (about 80%) and increasing energy efficiency (about 20%), comparing with traditional solutions.



Dagnija Blumberga


European Regional Development Fund


From 1st April 2017 until 31st March 2020


595 843,79 EUR





The project “Individual Heat Supply with Integrated Fog Unit System (IFUS)” collects experimental data at three boiler capacities (10 kW, 20 kW, 30 kW) and nozzles (MPL 1.51, MPL 1.12, MPL 0.77) used to obtain the data set to be analysed. The data analysis program Statgraphics XVII performed experimental data analysis to determine what parameters affect the capacity of the fog unit and the efficiency of particulate matter (PM).

Regression analysis was performed to determine the parameters affecting the capacity of the fog unit, in which the dependent variables are:

-Flue gas temperature at inlet (tg1) and outlet (tg2);

-Water temperature at inlet (tw1) and outlet (tw2);

-Flue gas moisture content at inlet (ω1) and outlet (ω2);

-Wet flue gas flow (Vmg);

-Amount of water sprayed (G);

-Injected water – flue gas ratio (g/Vmg);

-Diameter of sprayed water droplets (dd0);

-Oxygen concentration in the flue gas (O2);

-Flue gas velocity at inlet (ug1) and outlet (ug2);

-The amount of water sprayed per unit cross-section (g/SMA).

The most important factors affecting the capacity of the fog unit are: tw1, dd0, g/Vmg, G, tw2, Vmg.

Regression analysis was performed to determine the parameters affecting PM reduction efficiency, where the dependent variables are:

-tg1, tg2, tw1, tw2, ω1, ω2, Vmg, G, g/Vmg, dd0, O2, ug1, ug2, g/SMA;

-injected water – droplet diameter ratio (g/dd0);

-surface formed by injection droplets in the fog unit (Fdrop);

-concentration of particulate matter before the fog unit (PM before)

The most important factors that influence the PM reduction efficiency of the fog unit are: tg2, tw2, ω2, Vmg, G, g/Vmg.

The study is also featured on LTV1 broadcast “Environmental Facts”. The storyline of the show about air pollution can be found here.

Posted on the website: 30.12.2019.

Within the framework of the activity 3.2, a program was developed, which includes a calculation model to describe the operation of the fog unit. The program is based on a pre-built mathematical model in the Excel environment (activity 1.3), which has been refined and transferred to another environment, facilitating faster calculations. Program written in PYTHON 3.7 using Visual Studio 2019. It includes the calculation of the thermal-physical parameters, the auxiliary equations and the calculation of changes in the main parameters. The main parameters, whose changes are considered in the model, are: injected water temperature, temperature of the flue gas, diameter and velocity of the water droplets, concentration of particulate matter and moisture content of the gas. Using the model data obtained, the heat capacity of the fog unit was also calculated.

The experimental data set includes measurements at three different boiler capacities (10 kW to 30 kW), injected water temperature (20 – 40 oC) and each water injection nozzle. Various injected water flow rates in each mode (45 l/h to 342 l/h) were tested, as well as the effect of oxygen concentration on the flue gas parameters.

Testing of the developed model takes place using data obtained from experiments as input data for calculation. The obtained results are summarized and compared with the data of the corresponding experiment at the beginning and end of the experiment to evaluate the correspondence of theoretically obtained parameters to the real situation. Reviewing the results obtained helps to improve and refine the model.

Posted on the website: 26.11.2019.