Performance Analysis of a Waste-to-Energy System Integrated with the Steam–Water Cycle and Urea Hydrolysis Process of a Coal-Fired Power Unit

An innovative hybrid energy system consisting of a waste-to-energy unit and a coal-fired power unit is designed to enhance the energy recovery of waste and decrease the investment costs of waste-to-energy unit. In this integrated design, partial cold reheat steam of the coal-fired unit is heated by the waste-to-energy boiler’s superheater. The heat required for partial preheated air of waste-to-energy unit and its feedwater are supplied by the feedwater of CFPU. In addition, an additional evaporator is deployed in the waste-to-energy boiler, of which the outlet stream is utilized to provide the heat source for the urea hydrolysis unit of coal-fired power plant. The stand-alone and proposed designs are analyzed and compared through thermodynamic and economic methods. Results indicate that the net total energy efficiency increases from 41.84% to 42.12%, and the net total exergy efficiency rises from 41.19% to 41.46% after system integration. Moreover, the energy efficiency and exergy efficiency of waste-to-energy system are enhanced by 10.48% and 9.92%, respectively. The dynamic payback period of new waste-to-energy system is cut down from 11.39 years to 5.48 years, and an additional net present value of $14.42 million is got than before.

Mobile Off-Grid Energy Generation Unit for Temporary Energy Supply

Temporary structures are being extensively used by emergency services (rescue, disaster relief, military response units), and other end-users requiring temporary mobile off-grid energy solutions for different purposes (event organization, vacation homes, summer camps, etc.). Yet energy systems for these purposes largely remain fossil-based (such as diesel generators). Although such energy systems are inexpensive, they are carbon intensive and inefficient. This study presents a methodology of simulating temporary shelter with access to an energy supply system through a mobile energy unit with renewable (PV) power supply systems to ensure on-site electricity production, as well as heating/cooling and ventilation. Digital modeling simulations have been performed for a simulated temporary shelter in different climate conditions incorporating different combinations of electricity generation systems with a fossil fuel-based solution and a PV system, using TRNSYS software. Study results show that the operation of a mobile energy generation unit can operate HVAC systems and generate electricity for temporary shelter occupants in off-grid solutions. The modeling results show that the use of a mobile energy generation unit can significantly reduce diesel consumption in temporary shelters from 54% annually (in Riga, Latvia) to 96 % annually (in Jerusalem, Israel). Furthermore, the output of PV-generated electricity is higher (in most cases) than the consumed electricity amount.

Determination of the Model Basis for Assessing the Vehicle Energy Efficiency in Urban Traffic

The paper studies the problem of assessing the vehicle energy efficiency on the streets of urban road network. As a result of morphological analysis of the system “Vehicle—Traffic flow—Road—Traffic Environment” 18 significant morphological attributes of its functional elements, that affect the energy efficiency of vehicles, were identified. Each attribute is characterized by 3–6 implementation variants, which are evaluated by the relevant quantitative or qualitative parameters. The energy efficiency of vehicles is determined by the criteria of their energy consumption considering the vehicle category, type of energy unit, mode of vehicle movement and adjustment factors—road, climatic and others. The input parameters values of the system in the process of traffic flow on the linear fragments of streets and road networks of the cities of Ukraine and Poland were measured. The set of independent system parameters is determined by applying the Farrar-Glober method based on statistical estimates. The specified set is the basis of the studied system and is formed of 10 independent input parameters. The presence in the basis of parameters that correspond to the morphological features of all four functional elements, confirmed the importance of these elements of the system. The mathematical dependence of the impact of vehicle characteristics, traffic flow, road and environment on vehicle energy efficiency is built. The standard deviation of the model values from the tabular ones equals σ´=0.0091. Relative standard deviation equals S´r=1.5%. The results of the study could be used in the development of new and optimization of existing intelligent traffic control systems of urban transport.

REDUCING TOTAL ENERGY COSTS FOR TECHNOLOGICAL OPERATIONS IN AGRICULTURE - A WAY TO REDUCE GREENHOUSE GAS EMISSIONS TO THE ATMOSPHERE

The article is devoted to the search for ways to reduce carbon dioxide emissions into the atmosphere when performing technological operations in agricultural production. It is proposed to calculate the efficiency of using machine and tractor units based on the methods of physical economics, when not a monetary unit is used as an indicator of efficiency, but an energy unit, which is an indirect indicator of saving or increasing emissions of carbon dioxide. It is substantiated that a decrease in total energy costs when performing technological operations for the production of grain and other crops directly leads to a decrease in greenhouse gas emissions into the atmosphere. Examples of computational experiments are given to identify the most optimal brand of a tractor and optimize the parameters of the working width and speed of the seeding machine-tractor unit K-5250 + Agromaster, leading to a decrease in total energy costs and, accordingly, to a decrease in carbon dioxide emissions and carbon sequestration from the air by reducing losses harvest

Spatial analysis of public residential housing's electricity consumption in relation to urban landscape and building characteristics: A case study in Singapore

In a highly populated country like Singapore, a significant percentage of our gross annual electricity consumption stems from our domestic electricity usage in our residential houses. Analyzing and understanding factors that could influence such patterns is thus essential in order to derive effective measures to reduce usage. In this research, 16 identified variables were calculated and considered in the spatial analyses based on various buffer sizes. Both multilinear regression (MLR) and geographically weighted regression (GWR) based analyses were conducted using each residential housing's Energy Unit Intensity (EUI) as the dependent variable. The analyzed results have shown that building characteristics variables have more significant influences towards energy consumption patterns as compared to urban landscape variables. Although little difference was observed across different buffer sizes, more reliable results were obtained from a smaller buffer size of 50 m, suggesting its suitability in using these obtained values for further prediction model analysis and development. Results obtained from the GWR-based analysis have shown a significant improvement in the goodness-of-fit value compared to the MLR-based analysis, effectively indicating that GWR performs better in this context, apart from its better explanation on the contribution of these identified variables to the EUI in this case study.

IMPROVE THE PYROLYTIC GAS PRODUCTION BY USING THE CO-PYROLYSIS TECHNIQUE : AN EXPERIMENTAL STUDY

The target of the biomass co-pyrolysis is improvingthe heating value of the produced bio-products of a certain type of feedstock, besides disposal of more than one residue in the same time. Thus, this work aims to operate a local fabricated fixed-bed pyrolyzer to improve the pyrolytic gas yield produced by the ground pieces of three biomass residues namely Mango trees Pruning Logs (MPL), Sugarcane bagasse (SB) and Rice straw (RS) using an affordable slow pyrolysis technique. This work was carried out under slow pyrolysis conditions represented in final pyrolysis temperature of 400 °C, vapor residence time of 4 min, heating rate of 0.01-1 °C/s in full absence of oxygen. The pyrolytic gas production was assessed under different feedstock mixing ratios of (1:2:1), (1:1:2) and (2:1:1) as ratio of (RS: SB: MPL), particle lengths of 1-5, 10-15 and 20-25 mm, with and without sandy bed at the bottom of pyrolysis chamber as a fluidized bed. The obtained results showed that, using the fluidized fixed-bed pyrolyzer under slow co-pyrolysis conditions gave the optimum results where in, the pyrolytic gas concentration, gas yield, higher heating value of pyrolytic gasand energy conversion efficiency were 55%, 1.09 Nm3 /kg, 14.97 MJ/Nm3 and 85.43%, respectively, and 53.7%, 1.08 Nm3 /kg, 13.75 MJ/Nm3 ,77.71% in case of using the pyrolyzer without fluidized bed under the same operating conditions. So, the pyrolyzer with fluidized bed achieves an increment in the higher heating value and energy conversion efficiency by about 8.15% and 9.03%, respectivly over the pyrolyzer without fluidized bed.Furthermore, the cost per energy unit of pyrolytic gas produced by the fluidized bed pyrolyzer is lower than the common two fossil gaseous fuels of natural gas and LPG costs by about 28.57% and 80%, respectively.

An Investigation into the Development of the Force and Energy Unit through STEM Integration in Science Course and its Effects on Students' Critical Thinking Skills

In this study, to examine the change in individuals' critical thinking skills, a new unit was developed in which STEM was integrated. The outcomes of this 7th-grade unit were selected from related disciplines. During the learning process of the developed Force and Energy unit, it was aimed that individuals could make judgments by gaining critical thinking skills and evaluate events in a multi-dimensional way. In this study, which lasted for five weeks, the developed unit was used to conduct lessons with the experimental group (N=25) while the control group (N=25) was traditionally taught. The Critical Thinking Scales developed by Demir (2006a) were used in the research process. Before the implementation, no significant difference was found between the experimental and control groups regarding critical thinking skills, but after the implementation, a significant difference was observed in favour of the experimental group. When the scores obtained from the sub-scales (interpretation and explanation) were compared, a significant difference was found in favour of the experimental group. When the changes in the experimental and control groups were examined, there was no significant change in the control group students, but a significant change was found in favour of the experimental group. These changes occurred in the evaluation, Interpretation, and explanation sub-scales of the critical thinking scale.

DEVELOPMENT OF CONCEPTUAL TECHNICAL SOLUTIONS AND METHODS OF THEIR IMPLEMENTATION DURING THE DESIGN OF A DUST COAL STEAM GENERATOR OF SUPER-SUPER CRITICAL PARAMETERS OF STEAM 28 MPA / 600 °C/600 °C FOR 300 MW ENERGY UNIT. PART 3.

In the third part of this article, an attempt is made to expand the range of regulation of the steam generator load from 40% to 100% by injecting recirculating flue gases taken after the water economizer into the middle radiation part of the furnace. For this, verification thermal calculations of the boiler were carried out when burning ДГ-100 coal in a wide range of variation of the recirculation coefficient Krec = 10−20% at loads of 40% and 50% of the nominal. It is shown that: a) at a load of 50%, recirculation of flue gases Krec = 13 % leads to a drop in the steam temperature along the primary path, due to which the maximum wall temperatures of all-welded screens decrease, which makes it possible to reduce the cost of boiler manufacture by reducing the use of expensive austenitic steels by 116.3 t; b) to ensure a live steam temperature of 600 °С at a load of 40%, it is necessary that Krec = 12%. This leads to a rise in the cost of the boiler in comparison with the load of 50% due to the use of steel grade 10X16N16V2MBR in the manufacture of ceiling screens. Bibl. 3, Fig. 17, Tab. 4.