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1.
Carbon-free heat production for high-temperature heating systems
Sven Gruber, Klemen Rola, Danijela Urbancl, Darko Goričanec, 2023, original scientific article

Abstract: The article presents a new carbon-free heat production technology for district heating, which consists of a combined heat and power generation fuel cell (FC CHP) with CO2 capture and a two-stage cascade high-temperature heat pump (TCHHP). The FC generates heat and electricity, the latter being used to drive the compressors of the TCHHP. During the winter period, the water temperature achieved can occasionally be too low, so it would be heated up with hydrogen gas boilers. The hydrogen would be produced by reforming natural gas, synthetic methane, or biogas. The results are presented with natural gas utilization—the ratio between the obtained heat flow transferred directly to the water for district heating and the input heat flow of natural gas. In the case of a return water temperature of 60 °C and district heating temperature of 85 °C, the TCHHP, whose heat source is groundwater, achieves plant efficiency of 270.04% in relation to the higher heating value (HHV) and 241.74% in relation to the lower heating value (LHV) of natural gas. A case with a TCHHP whose heat source is low-temperature geothermal water achieves a plant efficiency of 361.36% in relation to the HHV and 323.49% in relation to the LHV.
Keywords: carbon-free, decarbonization of district heating systems, fuell cell, high-temperature district heating, high-temperature heat pump
Published in DKUM: 10.05.2024; Views: 88; Downloads: 2
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2.
Geothermal heat potential - the source for heating greenhouses in Southestern Europe
Danijela Urbancl, Peter Trop, Darko Goričanec, 2016, original scientific article

Abstract: 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.
Keywords: geothermal heat exploitation, greenhouses energy demands, high temperature heat pump, economic analysis
Published in DKUM: 07.07.2017; Views: 1391; Downloads: 382
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3.
Optimal proportion of refrigerants in single- stage high-temperature heat pump
Milovan Jotanović, Mirko Miščević, Bojan Kulčar, Darko Goričanec, 2012, original scientific article

Abstract: The paper presents types of refrigerants with their characteristics for use insingle-stage high-temperature heat pump. A mathematical model is designed; based on the use of the modeling language GAMS a simulation of optimum mixtureproportions of two refrigerants was made, which allows for the heat pump to operate the most efficient. Software package Math Cad Professional wasused to make calculations of the characteristic properties of the heat pump.
Keywords: heat transfer, single-stage high temperature pump, refrigerant, simulation of effect
Published in DKUM: 10.07.2015; Views: 1187; Downloads: 42
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