IMPACT OF REDUCED HEATING DEMAND ON GREENHOUSE GASES EMISSION UNDER COST-OPTIMAL OPERATION OF COGENERATION PLANTS

Demand-side energy efficiency measures in buildings are usually considered advantageous from the environmental aspect. Similarly, the implementation of modern flexible energy-efficient cogeneration plants is often beneficial in respect for energy consumption and the environmental impact. However, the joint effects of these two approaches towards energy efficiency and greenhouse gases emission reduction are: dependent on many factors, more complex and harder to estimate. This paper analyses the impact of residential buildings heating demand reduction on greenhouse gases emission from a cogeneration plant. It illustrates realistic scenarios in which the reduction of heating demand might lead to the increase of greenhouse gases emission when an energy supply system operates in a cost-optimal manner

Combined Contribution of Endothelial Relaxing Autacoides in the Rat Femoral Artery Response to CPCA: An Adenosine A2 Receptor Agonist

We examined the contribution of endothelial relaxing factors and potassium channels in actions of CPCA, potent adenosine A2 receptor agonist, on isolated intact male rat femoral artery (FA). CPCA produced concentration-dependent relaxation of FA, which was notably, but not completely, reduced after endothelial denudation. DPCPX, A1 receptor antagonist, had no significant effect, while SCH 58261 (A2A receptor antagonist) notably reduced CPCA-evoked effect. Pharmacological inhibition of nitric oxide synthase or cyclooxygenase comparably reduced CPCA-evoked action, still in a lesser degree than after denudation. In the presence of buffer with high K+ (100  mM), CPCA-produced relaxations were almost abolished. TEA (nonselective KCa blocker), glibenclamide (KATP blocker), Ba++ (KIR blocker), or ouabain (Na+/K+-ATPase inhibitor) did not change CPCA-induced relaxation. Concentration-response curve for CPCA was significantly shifted to the right after the incubation of apamin (SK channel blocker). CPCA produced concentration-dependent relaxation of FA that was partly dependent on endothelial cells. Endothelium-related portion of CPCA-elicited effect was mediated by combined action of endothelial NO, prostacyclin, and EDHF after activation of endothelial A2A receptors. Small conductance KCa channels were involved in this action

Avoidable and unavoidable exergy destruction and exergoeconomic evaluation of the thermal processes in a real industrial plant

Exergy analysis is a universal method for evaluating the rational use of energy. It can be applied to any kind of energy conversion system or chemical process. An exergy analysis identifies the location, the magnitude and the causes of thermodynamic inefficiencies and enhances understanding of the energy conversion processes in complex systems. Conventional exergy analyses pinpoint components and processes with high irreversibility. To overcome the limitations of the conventional analyses and to increase our knowledge about a plant, advanced exergy-based analyses are developed. These analyses provide additional information about component interactions and reveal the real potential for improvement of each component constituting a system, as well as of the overall system. In this paper, a real industrial plant is analyzed using both conventional and advanced exergy analyses, and exergoeconomic evaluation. Some of the exergy destruction in the plant components is unavoidable and constrained by technological, physical and economic limitations. Calculations related to the total avoidable exergy destruction caused by each component of the plant supplement the outcome of the conventional exergy analysis. Based on the all-reaching analysis, by improving the boiler operation (elimination of approximately 1 MW of avoidable exergy destruction in the steam boiler) the greatest improvement in the efficiency of the overall system can be achieved

Bin weather data for City of Niš

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SPLITTING THE TOTAL EXERGY DESTRUCTION INTO THE ENDOGENOUS AND EXOGENOUS PARTS OF THE THERMAL PROCESSES IN A REAL INDUSTRIAL PLANT

The total exergy destruction occurring in a component is not only due to the component itself (endogenous exergy destruction) but is also caused by the inefficiencies of the remaining system components (exogenous exergy destruction). Hence care must be taken in using the total exergy destruction of a component for making decisions to optimize the overall energy system. In this paper, a complex industrial plant is analyzed by splitting the component’s exergy destruction into its endogenous part (the part resulting totally from the component’s irreversibilities) and its exogenous part (resulting from the irreversibilities of the other components within the system). It is observed that the steam generator has the dominant effect. From the total exergy destruction in the steam generator, 1,097.63 kW or 96.95% come from internal irreversibilities in the component, while the influence of other components on the loss of useful work in the steam generator is only 3.05%

POSSIBILITIES TO MINIMIZE GREENHOUSE GASES EMISSION AND MAINTAIN THERMAL COMFORT IN OFFICE BUILDINGS WITH CO-SIMULATION ASSISTED OPERATION OF AIR HANDLING UNITS

Energy efficiency measures in existing buildings include improvements in heating, ventilation and air conditioning systems but from the perspective of system renovation and components upgrade. These measures target the building energy consumption and resulting greenhouse gases emissions, with thermal comfort of occupants being seen only by one or two parameters. Improvements in existing system operation can lead to minimal greenhouse gases emission, but with thermal comfort maintained at the desired level. This paper evaluates the possibility to minimize greenhouse gases emission while maintaining occupant thermal comfort within prescribed class, by optimizing the existing air conditioning system operation with 5 weekdays planning horizon. Particle swarm optimization method is used. The paper shifts the focus from minimal emissions to minimal emissions for desired thermal comfort range, without system renovation or upgrade. The results show that maintaining thermal comfort results in higher greenhouse gases emission compared to usual system operation where emissions are lower but thermal comfort is outside desired range almost all the time

The kinetic study of juice industry residues drying process based on TG-DTG experimental data

To achieve sustainable development and mitigate the climate change challenges, the use of food industry residues is an important part of the modern circular econ- omy. The residues from the fruit juice production industry are nowadays commonly used raw materials for producing different value-added products. In order to improve the energy efficiency aspects of the industry residue treatment, generally, the drying process as the first step of the whole processing chain should be further analyzed. Regarding these facts, a comprehensive kinetic study was performed to provide the detailed mechanisms of moisture removal from the base raw material. The industrial residues from apple juice production were used for experimental isothermal TG anal- ysis in the air atmosphere at five different temperatures. Based on experimental data, different kinetic models were applied to determine the kinetic parameters and dom- inant conversion functions. The obtained results of activation energy were compared with literature data and further discussion about the decomposition mechanisms was provided. The results of this research will be further used for developing the univer- sal mathematical model of the drying process which could be applied for other sim- ilar food materials and could provide new data for the energy efficiency improve- ment of the food residues processing industry.ICTAC 2020 17th International Congress on Thermal Analysis and Calorimetry, 29 Aug. – 2 Sept. 202

Impact of agro-ecological conditions and fertilization on yield and quality of triticale on pseudogley soil

The results of the study of the influence of fertilization and calcification on the yield and yield components of winter triticale grown on low pH soil are presented in this paper. Five variants of fertilization were tested during three growing seasons. Trial treatments included different fertilization variants: V1-control, V2-N120, V3-N120P80K60, V4-N120P80K60 + 5 t ha- 1 of lime and V5-N120P80K60 + 5 t ha-1 of lime + 30 t ha-1 of manure. The results of the research showed that all yield components responded positively to the application of mineral nutrition by changing the production characteristics and grain quality. The variant with the combined application of NPK, lime and manure had the greatest positive effect on all tested parameters affecting triticale productivity. During the study, the highest yield of triticale 5.826 t ha-1 was obtained on the fertilization variant with the combined application of lime, manure and NPK fertilizers. The achieved increase in the grain yield of triticale was significant compared to the control and the NPK variant of fertilization. Highly significant positive dependencies were found between the grain yield with 1000-grain weight, and test weight and significant positive dependencies were found between 1000-grain weight and test weight. Theresearch highlighted the impact of different fertilizer treatments on the yield and grain quality traits of winter triticale