Ivan Hrušovský

Moment of Lignocellulosic Materials Ignition Defined by Critical Mass Flow Rate

On the base of experimental observations of mass loss rate in dependance of time in isothermal condition in circulating air atmosphere was determined the moment of lignocellulosic materials ignition. Experiment was performed in an electrically heated hot-air furnace according to ISO 871 standard (Setchkin furnace) in conjunction with precision scales. Experiment was performed with ignition source. The ignition source was kanthal wire. Experiment was performed at one temperature, three positions of samples in the oven and various air-flow speeds. Pure cellulose as a model compound was impregnated by water solution of KHCO3 and (NH4)2HPO4.

Monitoring of Thermal Degradation of Fireproof Coating

Under the fire conditions, the resistance of cable distribution is required for a fixed period, depending on the intended use of the cable. To increase the fire resistance of cables a fireproof coating may be applied. Article deal with the behavior of the fireproof coating during elevated temperature. Concretely, the aim is monitored a coating weight change under the conditions of dynamically increasing temperature and with or without using air-flow. It is also monitored the change in weight, depending on the isothermal temperatures in dynamic air atmosphere.

DTA Evaluation of Spruce Wood Degradation Process

Abstract The decomposition stages of spruce wood sawdust were analyzed by means of sequential differential calorimetry. Two stages of decomposition were identified and activation energy of one stage was calculated using the Kissinger method. The DTA was conducted by means of SEDEX safety calorimeter. Sample was analyzed under three heating rates of 10, 20 and 45 °C/h in temperature range from room temperature to 400 °C. The calculated activation energy for the last and most clear decomposition peak was 122.63 KJ/mol. The results are comparable with the data calculated by J.V. Rissanen et al., who calculated activation energy for Spruce hemicellulose as 120 KJ/mol.

Ignition activation energy of materials based on polyamide 6

Abstract This contribution is aimed to compare the values of the ignition activation energies of two types of polyamide – Slovamid 6 FRB and Slovamid GF 50 LTS. Samples were isothermally stressed at five different temperatures between 500 °C a 550 °C, while the time to initiation of the flame combustion was monitored. Subsequently from the measured times were compiled Arrhenius plots under which activation energy of ignition of both polymers were calculated. The values of activation energies were 106 kJ.mol−1 and 158.0 kJ.mol−1 for Slovamid 6 FRB 4 and Slovamid 6 GF 50 LTS.

Investigation Of Spontaneous Combustion Tendency Of Vegetable Oils By The Means Of Differential Thermal Analysis

Abstract The potential of vegetable oils to undergo violent thermal oxidation is long-known problem. The process of this oxidation is investigated by the means of differential thermal analysis. Polyurethane foam was saturated with Tung oil rich in unsaturated fatty acids at three different mass rations, and airflow at three different rates is introduces to the sample to ensure sufficient volume of air for oxidation. The samples were thermally stressed both dynamically and isothermally. The results were compared to results of standard differential Mackey test.

Fire Risk Assessment of Spruce Pellets

In the presented paper is assessed fire risk of pellets made from spruce wood (Picea abies L.) without bark, processed by hot pressing without the use of additional chemicals. Fire risk was assessed on the basis of heat release rate (HRR), the specific carbon monoxide production rate (SCPR) and the time dependence of the induction period of spontaneous ignition on temperature. HRR and SPCR were determined on the cone calorimeter test performed according to ISO 5660-1:2002 standard. Samples were loaded by 20 kW/m2 heat flux during the test. The maximum HRR was 229 kW/m2 and average HRR was 55 kW/m2. Maximum SCPR was 0.37 g/(m2s) and the average SCPR was 0.16 g/(m2s). The dependence of the induction period of spontaneous ignition on temperature was determined by a modified test performed according to ISO 871:2006 standard. Modification of the test procedure was based on measurement of the induction time period of the spontaneous ignition on temperature, and temperatures higher of 20, 40, 60, 80 and 100 °C than spontaneous ignition temperature. The obtained data proved an exponential dependence of the induction period of spontaneous ignition on temperature.

Study of Basic Characteristics of Hydrogen Generator

HHO technology appeared in USA in 1950s but only in last years it became more interesting due to rising of fossil fuels price. In a device called HHO generator, hydrogen and oxygen are produced onboard on vehicle by electrolysis of water solution of NaOH or KOH. This mixture of gases is known as a HHO gas and it is used as an additive to gasoline in conventional internal combustion engines. Construction of a HHO generator is relatively simply process with small money requirements. All measurements were realized with 10% KOH solution because this electrolyte at this concentration is considered as the best available one. KOH solution excels in chemical stability and efficiency of HHO gas production. For comparison, the 10% NaOH solution was prepared because of low price and good availability of NaOH and all measurements were repeated and results were compared.

Investigation of Airflow Influence on Self-Heating Process of Linseed Oil Using Safety Calorimeter SEDEX

The oxidative self-heating process of vegetable oil with high content of unsaturated fatty acids was investigated by the means of sequential scanning calorimetry in safety calorimeter SEDEX. The oil was applied on the cotton, and was put to the standard pressure sample vessel, which was modified for air inlet. The behavior of sample was studied under three rates of air flow. First experiment was carried out in the temperature range between approximately 30 and 350°C at a heating rate of 45°C/h. Second scanning was carried out in the temperature range from 30 to 200°C at heating rate of 10°C/h.

Monitoring of the Cellulose Pyrolysis in a Modified Electrically Heated Hot Air Furnace

This paper deals with monitoring of the thermal decomposition of pure cellulose in a modified electrically heated hot air furnace, which allows simultaneous measure of weight loss, released gases (CO, CO2, CxHy, H2, NO, NO2 and O2) at a given temperature or a selected heating rate and the selected airflow speed. The measurements were made under isothermal conditions in the temperature range 230-340 ° C and air flow at speeds 30, 20, 10, 0 mm.s.