Exploitation of Excess Low-Temperature Heat Sources from Cogeneration Gas Engines

The chapter presents an innovative technical solution for the use of low-temperature excess heat from the combined heat and power (CHP) of gas engines using gas or liquid fuel for district heating, building heating or industry. The primary fuel efficiency of CHP gas engines for heat production can be significantly increased by using the low-temperature excess heat of the exhaust gasses and the cooling system of the CHP gas engine, which are released into the environment thereby also reducing CO2 emissions. District heating hot water systems generally work with higher temperatures of the heating water, which is transported to the heat consumer via the supply line, and the cooled heating water is returned to the CHP gas engine via the return line. In order to make use of the excess low-temperature heat of the exhaust gasses and the cooling system of the CHP gas engine, a condenser must be installed in the exhaust pipe in which the water vapor contained in the exhaust gasses condenses and a mixture of water and glycol is heated, which later leads to the evaporator of the high-temperature heat pump (HTHP). The cooled heating water is returned from the heat consumer via the district heating return pipe to a condenser of one or more HTHPs connected in series, where it is reheated and then sent to a CHP gas engine, where it is reheated to the final temperature. The Aspen plus software package is used to run a computer simulation of one or more HTHPs connected in series and parallel to the district heating system and to demonstrate the economics of using the excess heat from the exhaust gasses and the cooling system of the CHP gas engine

External atmospheric influences on the mechanical properties of resin-bonded grinding wheels with aluminium oxide and silicon carbide grains

Ageing effects on resin-bonded grinding wheel properties are presented, including aluminium oxide and silicon carbide influence. Furthermore, humidity is examined as the most likely cause of significant downgrade in mechanical properties. Toward this aim a new system of accelerated ageing of grinding wheels (additional humidification) is used under special atmospheric conditions. The mechanisms for microstructural changes during ageing are analysed, based on the microstructure exposure to thermo-mechanical impacts

External atmospheric influences on the mechanical properties of resin-bonded grinding wheels with aluminium oxide and silicon carbide grains

Ageing effects on resin-bonded grinding wheel properties are presented, including aluminium oxide and silicon carbide influence. Furthermore, humidity is examined as the most likely cause of significant downgrade in mechanical properties. Toward this aim a new system of accelerated ageing of grinding wheels (additional humidification) is used under special atmospheric conditions. The mechanisms for microstructural changes during ageing are analysed, based on the microstructure exposure to thermo-mechanical impacts

With food to health : proceedings of the 9th International scientific and professional conference

Proceedings contains 7 original scientific papers, 8 professional papers and 1 review paper which were presented at "9th International Scientific and Professional Conference WITH FOOD TO HEALTH", organised in following sections: Nutrition, Dietetics and diet therapy, Food safety, Food analysis, Production of safe food and food with added nutritional value

HOT WATER NETWORK OPTIMISATION AND WATER SCALE INFLUENECE ON HEAT TRANSFER OF HEATING SURFACES

Doktorska disertacija zajema tri sklope v katerih so predstavljene rešitve, ki lahko v znatni meri prispevajo k smotrni rabi energije, zmanjšanju škodljivih vplivov na okolje in posledično k ciljem, ki so prioriteta svetovne energetske in okoljske politike. Predstavljeni so statistični podatki o emisijah toplogrednih plinov in predlagani ukrepi za njihovo zmanjšanje. Raziskane so pretočno - tlačne zakonitosti sistema daljinskega ogrevanja ter z variacijo vplivnih parametrov v optimizacijskem modelu analiziran vpliv na potek optimalnih drevesnih poti v zankastem omrežju. Podrobneje je predstavljena morfologija vodnega kamna, katerega glavna sestavina je kalcijev karbonat v kalcitni ali aragonitni strukturi. V sklopu eksperimentalnega dela so izvedeni preizkusi izločanja vodnega kamna na grelcih bojlerjev za toplo vodo in na grelcih pralnih strojev. Analiziran je vpliv dvovalentnih ionov na kristalno obliko vodnega kamna in podana ocena zmanjšanega prenosa toplote zaradi oblog na grelcih iz različnih materialov. Predlagana je optimalna namestitev grelcev in oblika kadi, ki zagotavlja dobro turbulenco toka vode in manjšo tvorbo vodnega kamna.The doctoral dissertation consists of three substantive wholes, where solutions that can contribute to rational use of energy and the reduction of harmful effects on the environment are presented, aiming at goals, which are the priority of world energy and environmental policies. Additionally, the statistical data of greenhouse gas emissions and suggested measures for their reduction are presented. Furthermore, flow – pressure conditions of district heating systems are researched. Also, with the variation of influential parameters in optimization model the impact on the course of optimal tree ways in loopy networks are analyzed. The water scale morphology is presented in more detail. Its most common component is calcium carbonate in aragonite or calcite shape. Some experiments were conducted for the evaluation of water scale precipitation on heaters of boilers for hot water and on washing machine heaters. The effect of divalent ions on crystal structure of water scale is analysed and the evaluation of heat transfer reduction because of scale deposits on heaters from different materials is given. A suggestion for an optimal installation of heaters and the shape of vat is made for assuring well water turbulence and less scale deposits

Assessing energy potential and chemical composition of food waste thermodynamic conversion products: a literature review

This study examines the considerable volume of food waste generated annually in Slovenia, which amounted to over 143,000 tons in 2020. The analysis shows that 40% of food waste consists of edible parts, highlighting the potential for reduction through increased consumer awareness and attitudes towards food consumption. The study shows that the consumption phase contributes the most to waste food (46%), followed by primary production (25%) and processing/manufacture (24%). The study addresses various thermodynamic processes, in particular, thermal conversion methods, such as torrefaction pyrolysis and hydrothermal carbonization, which optimize energy potential by reducing the atomic ratio (H/C) and (O/C), thereby increasing calorific value and facilitating the production of solid fuels. The main results show the effectiveness of torrefaction, pyrolysis and hydrothermal carbonization (HTC) in increasing the energy potential of food waste