Experimental Studies of Structural and Technological Parameters of a Downdraft Gasifier Based on Plant Biomass

The relevance of the study is conditioned upon the need to develop and implement structural and technological solutions to improve the efficiency of the chemical and thermal conversion of biomass into combustible gas. Within the framework of the above, the authors of this paper have designed a downdraft gasifier running on plant biomass. The presented research links the heat quantity received from the utilisation of syngas produced during the gasifier operation cycle with the parameters of the gas blow regime and the physico-chemical properties of biomass. For an in-depth study of the influence of the gas blow regime on the yield and calorific value of syngas produced from biomass, the authors introduce the concept of the blow coverage quality coefficient. This coefficient describes the quality of the cross-section coverage of the gasification chamber neck with gas currents of the tuyere zone. The purpose of this study is to establish the influence of the blow coverage quality coefficient, the volume of blow gases and the void ratio of the bulk biomass layer on the heat quantity received from syngas produced during the gasifier operation cycle. A multi-factor experiment was planned and performed, which relates the dependent factor to variables, and the corresponding response surfaces were constructed. The research findings are that the maximum value of the heat quantity received from the utilisation of syngas produced during the one-hour gasifier operation cycle was 519 MJ. This value is achieved with 0.8 blow coverage quality coefficient and a blow gas volume of 47.4 m3/h and 46.75% void ratio of the bulk biomass layer. The measurement results are highly consistent with the calculated data. The coefficient of determination was R2=0.983. The practical value of this study is to substantiate the rational design and technological parameters of the downdraft biomass gasifier operation, which will increase the efficiency of biomass energy production. The findings presented in this study can be used both to design new gasifiers and to improve the efficiency of the available ones

An Experimental Study on Operating Characteristic of Radiant Floor Cooling Integrated with Underfloor Ventilation System

In this paper, an experimental study on radiant floor cooling integrated with underfloor ventilation (RFCUV) system was conducted. Indoor environment temperatures, radiant floor cooling system parameters and underfloor ventilation system parameters were measured. Humane thermal comfort was analyzed experimentally. And the effects of disturbance variables and manipulated variables on controlled variables were analyzed. The results illustrated that operative temperature (OT), predicted mean vote (PMV) and predicted percent dissatisfied (PPD) decrease in the first two hours and then become stable in ISO7730 recommended value range. IAT and OT increase with the increasing of the disturbance variables and manipulated variables. The increasing ratio of indoor air temperature (IAT) and OT are relatively small when comprehensive outdoor air temperature is relatively high and indoor heat quantity or average water temperature is relatively low. IAT and OT increase approximately linearly with the increasing of supply air temperature.

A theoretical study on the mass input and output and energy of the biomedical waste incinerator

Medical waste production has increased with many government and private hospitals and health centres due to the increase in the population, especially in the spread of Coronavirus Covid-19. This increase in medical waste is treating in medical incinerators. One of the advantages of incineration is the reduction of volume, weight and energy recovery. This paper examines the medical waste incinerator of one of the Medical City hospitals in Baghdad, as this incinerator internally divided into primary and secondary chambers. The medical waste for yellow bags placed in the primary chamber is burned with the help of air and a burner of 178-356 kW, resulting in waste burned. Then the combustion products pass through the secondary chamber, wherewith air and another burner of 178-356 kW, the combustion of gases and volatile materials from the waste completed. Air is then supplied to the flue gases to dilute the emission concentrations and reduce the flue gas temperature. This paper presents a study on the inputs and outputs of waste, air, fuel and the advantage of the heat quantity generated from the combustion of biomedical waste. As a result of this theoretical work, this incinerator provides an acceptable and durable solution to waste disposal problems and the risks of spreading viruses today.

Electronic equipment measuring device for heat quantity through a flat wall

In the paper, an experimental study for calculation the heat quantity through a flat wall by electronic system has been presented. The aim is temperature measurement on outer and inner walls of a room for 20 days at 1-minute interval of measurement. A transient regime has been considered. The data measured has been collected on a non-insulated south wall of a Technical University of Varna campus building. The wall layers parameters have to be known for the choice of surrounding area. In order to reduce errors of the outer side of wall temperature measurement caused by the solar radiation, the temperature sensor has been painted grey. The experimental equipment for the heat quantity measurement consists of two plates, each with 4 temperature fixed in a rectangle. The sensors are situated in а flat area in order to obtaining more precise results of experimental study. The problem has been solved by finding decision of the classic heat conduction equation. The experimental temperatures are treated by microprocessor’s platform based on Arduino board. As a result, the average temperature of each plate with sensors has been estimated.

Heat Transfer Mechanism of Minimum Quantity Lubrication Grinding

Grinding temperature rise at the grinding interface has a great bearing on workpiece surface quality and service life of grinding wheel. In order to study influence degree of temperature on workpiece and analyze heat transfer at the grinding interface, as thermal influence at the grinding interface is regarded as a moving heat source on workpiece surface, influence of heat source on heat transfer will be investigated in the gradual expansion form of heat source by point, line, and surface on the theoretical foundation in Chapter 3. The influences of heat quantity transferred to workpiece and energy proportionality coefficient will be studied according to convective heat transfer theory on workpiece surface so as to provide a theoretical foundation for heat transfer of grinding temperature field model in the finite element simulation software.

Influence of Current Feeding Position of Duplex Current Feeding MIG Welding on Droplet Heat Quantity

Pure argon metal inert gas (MIG) welding is expected to offer the possibility to obtain high toughness weld joints. However, due to its arc instability and low wettability, it is difficult to apply pure argon MIG to a practical welding structure. In order to solve these problems, an improved MIG welding process with a duplex current feeding (DCF-MIG) mechanism was developed. In the DCF-MIG process, the welding current and the wire feeding speed are independently controlled by an additionally feeding secondary current from a secondary power source. Thereby, DCF-MIG can supply a large current compared to conventional MIG under the same deposition rate. In this study, to consider the influence of the secondary current feeding position of DCF-MIG on droplet heat quantity, droplet heat quantity was measured by calorimetry. As a result, the droplet heat quantity was found to be increased significantly with the increase of the distance between the primary current feeding point and secondary current feeding point. The increase of the droplet heat quantity in the DCF-MIG process had a strong effect on improving bead shape and penetration. The droplet heat quantity with the effective current value of DCF-MIG was derived from the simplified calculation and the results roughly agreed with the experimental data.

Quantity and Quality of Dual Fuel IC Marine Engine Exhaust Sensible Waste Heat Considering Different Sulphur Content in Fuels

Maritime transport is facing a significant set of technical challenges due to planned by the International Maritime Organization implementation of ecological criterions on 01 January 2020 and 2021 regarding the emission of sulphur oxides, carbon dioxide and nitrogen oxides. The advantageous properties of natural gas (NG) as fuel in conjunction with dual fuel (DF) internal combustion (IC) engines potentially enables the fulfilment of all planned criterions. However, if the methane emission of DF IC is taken into consideration in CO2 emission balance it completely devaluates the advantages arising from high hydrogen to carbon ratio of NG. On the other hand, the planned global sulphur cap in combination with its low content in NG potentially enables to recover higher rates of waste heat and exergy of combustion products without the risk of low temperature corrosion (compared to liquid fuel). In this study the influence of sulphur content in NG and pilot fuel on the sulphuric acid condensation temperature was investigated in order to determine the rate of waste heat (quantity) and exergy (quality) of four stroke DF IC engine combustion products. In ideal process scenario (exergy based) the methane slip effect compensation was achieved only for a 0,5 engine load.