Iskanje po katalogu digitalne knjižnice

Opis: The incorporation of ejectors into heat pump and refrigeration cycles has been the subject of growing interest, largely due to their simple structure, high reliability, and cost-effectiveness. This paper investigates the recent advancements in novel design concepts of ejector-enhanced vapor compression heat pump and refrigeration cycles. An overview of novel single-stage and twostage compression cycles utilizing a single or multiple ejectors is provided. First, the system setup, operational principles, description, and figures of the existing schemes are provided. Second, the main results, such as the coefficient of performance (COP), volumetric heating capacity and exergy destruction, are discussed. In conclusion, the paper presents a coherent summary of the current developments, future prospects, and the current knowledge gap. A plethora of research is present in developing theoretical systems with high efficiency. However, experimental tests for real-life implementations are limited. This review aims to provide the reader with an overview of recent theoretical and experimental studies.
Ključne besede: ejector, heat pump, refrigeration, vapor compression system, review
Objavljeno v DKUM: 03.09.2024; Ogledov: 51; Prenosov: 11
Celotno besedilo (10,04 MB)

Opis: This paper presents the conceptual design of a technological solution for the efficient conversion of food waste into heat and power. The distribution and composition of food loss and waste at different stages of the food supply chain in Slovenia and their potential for biogas production were determined. It was found that more than 50% of food waste comes from households. Therefore, a small plant was designed to convert food waste into biogas, which was innovatively coupled with a combined heat and power (CHP) unit and a heat pump. This doubles the amount of heat generated compared to conventional cogeneration. Based on the capacity of a micro commercial CHP unit, 3330 households (about 8000 residents) would supply food waste. The heat generated could replace 5% of the natural gas used for domestic water heating. The payback period would be 7.2 years at a heat price of about 80 EUR/MWh, however, for municipalities with more than 40,000 inhabitants the payback period would be reduced to less than 3 years. The cost price of the heat generated by this system would be about 25 EUR/MWh, taking into account the government subsidy for the operation of the CHP unit.
Ključne besede: food waste to energy, biogas, combined heat and power, CHP, heat pump, efficiency, conceptual design, preliminary economic assessment, sensitivity analysis
Objavljeno v DKUM: 16.02.2024; Ogledov: 3257; Prenosov: 28
Celotno besedilo (19,44 MB)
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Opis: The effects of global warming are a crucial issue in the near future. The combination of renewable energy sources (RES) and the use of alternative energy technology such as heat pumps and hydrogen technology could solve major ecological problems. In Central Europe, the energy demand for heating and cooling in residential buildings is clearly higher than for generation of electricity or energy for trucking e.g. In this paper, a new solar thermal absorber has been analysed which is produced by using the so called "roll bond" technology (ABS Network, 2018). The focus of this study lies on the determination of the energy efficiency by combining this solar thermal absorber with heat pumps and biomass or geothermal systems in the region of Central Europe.
Ključne besede: roll bond solar absorbers, thermal analysis, solar systems, heat pump systems, heating and cooling in residential buildings
Objavljeno v DKUM: 04.12.2023; Ogledov: 332; Prenosov: 32
Celotno besedilo (18,06 MB)
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Opis: The primary objective of this paper is to present a graphical user interface for the calculation of electricity produced by a photovoltaic system and electricity consumed by a heat pump. The produced electricity is determined by a multi-year average of measurements of the global and diffuse power density of solar radiation for several places in Slovenia, while consumed electricity is determined based on the required heat for heating a residential building and domestic water. The calculation of produced and consumed electricity is validated by measurements on a real system. The developed graphical user interface enables simple user inputs of the photovoltaic system, heat pump, and the considered residential building, and provides a comprehensive technical analysis for installing both systems at the same location.
Ključne besede: graphical user interface, photovoltaic system, heat pump, production of electricity, consumption of electricity
Objavljeno v DKUM: 13.11.2023; Ogledov: 278; Prenosov: 14
Celotno besedilo (2,75 MB)
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Opis: The paper presents economically evaluated solutions for heating greenhouses with geothermal potential, if the same greenhouse is placed in two different locations in Southeastern Europe, one in Slovenia and the other in Serbia. The direct geothermal water exploitation using heat exchangers is presented and the remaining heat potential of already used geothermal water is exploited using high temperature heat pumps. Energy demands for heating greenhouses are calculated considering climatic parameters of both locations. Furthermore, different constructions materials are taken into account, and energy demands are evaluated if the same greenhouse is made of 4 mm toughened single glass, double insulated glass or polycarbonate plates. The results show that the geothermal energy usage is economically feasible in both locations, because payback periods are in range from two to almost eight years for different scenarios.
Ključne besede: geothermal heat exploitation, greenhouses energy demands, high temperature heat pump, economic analysis
Objavljeno v DKUM: 07.07.2017; Ogledov: 1519; Prenosov: 396
Celotno besedilo (1,02 MB)
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