PSI - Issue 77

7

Michal Holubčík et al. / Procedia Structural Integrity 77 (2026) 413– 423 "Michal Holubčík" / Structural Integrity Procedia 00 (2026) 000 – 000

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Figure 4 : Schematic illustration of the smart experimental setup of the LOKCA biomass boiler

The individual subsystems are described as follows: PART A - IoT Monitoring Prototype of Combustion Quality

The wireless IoT prototype was developed to continuously monitor the combustion quality of the biomass boiler. It integrates multiple low-cost sensors, including MQ-7 for carbon monoxide, a DFRobot particulate matter sensor for TZL, and DFRobot I²C oxygen and SCD41 carbon dioxide sensors for excess air and combustion efficiency assessment. A PT100 thermocouple measures flue gas temperature, while an ENS160+BME280 module provides additional environmental parameters such as humidity, pressure, and VOCs. Data are transmitted via a DFRobot WiFi module to the ThingSpeak cloud platform, where they can be processed and visualized with MATLAB support. PART B - Module with Frequency Converters Precise control of the fuel supply and combustion air is ensured by a dedicated module equipped with two frequency converters. The INVT GD20-0R7G-S2- EU (0.75 kW, 230 V) regulates the air fan, while a second unit controls the pellet feeder motor (90 W) with an attached gearbox. Communication is enabled through an industrial WireShare RS 485 USB adapter supporting up to four devices simultaneously. This configuration provides fine-tuned regulation of pellet feeding rates in the range of 2.1– 4.6 kg/h and fan a ir flow from 11 to 113 m³/h, forming the foundation for

advanced adaptive control. ABB Monitoring Section

For reference and validation, a professional ABB AO 2020 flue gas analyzer was used to measure key emission components such as CO, NO, O₂, and CO₂. A chimney draft meter monitored pressure conditions, while a thermocouple ensured high-resolution flue gas t emperature data. This subsystem acted as the benchmark against which the low-cost IoT sensors were calibrated, confirming their suitability for combustion monitoring and intelligent regulation tasks.