https://etalpykla.vilniustech.lt/handle/123456789/154496 2026-04-05T18:34:34Z 2026-04-05T18:34:34Z Grzebielec, Andrzej Rusowicz, Artur Ziąbka, Tomasz https://etalpykla.vilniustech.lt/handle/123456789/154837 2024-09-05T09:25:08Z 2020-01-01T00:00:00Z

Correct selection of the ORC system parameters for the exhaust gases heat source Grzebielec, Andrzej; Rusowicz, Artur; Ziąbka, Tomasz Contrary to appearances, ORC (Organic Rankine Cycle) systems should not be selected for the highest available temperature of the upper heat source. This approach allows, of course, to achieve the highest energy efficiency, but this happens at the expense of the electrical power obtained. This solution would be good for an infinite heat source. In practice, there is always a finite heat source power. Therefore, the analysis should take into account other aspects than just maximum efficiency. The article presents a method of selecting ORC system parameters for a heat source in the form of waste gases, enabling the highest electrical power to be obtained. The analysis shows that even a significant reduction in the evaporation temperature of the working medium in the ORC system compared to the source temperature is beneficial for the profitability of investing in an ORC system. The analysis showed that for flue gases with temperatures of 300, 400, 500 and 600 °C, the best evaporating temperatures of the working medium in the ORC system are 145 °C, 185 °C, 214 °C and 250 °C, respectively. The highest level of generated electricity is obtained for these temperatures.

2020-01-01T00:00:00Z Grzebielec, Andrzej Szelągowski, Adam Bruzi, Krzysztof https://etalpykla.vilniustech.lt/handle/123456789/154836 2024-09-05T09:19:25Z 2020-01-01T00:00:00Z

Analysis of the possibilities of improving environmental conditions in lecture halls using mechanical ventilation Grzebielec, Andrzej; Szelągowski, Adam; Bruzi, Krzysztof Didactic classes are conducted in lecture halls usually adapted from the technical side to present content. Audiovisual and sound systems are installed. Unfortunately, in many cases, classrooms are designed from the point of view of air conditioning and ventilation, just like office rooms. As a result, during classes, even in rooms where air conditioning occurs, the conditions change so unfavourably that both teacher and students experience discomfort. The work analyzes the change in temperature, CO2 concentration, PM2.5 concentration and relative humidity in the room, where heat gains from people and equipment as well as moisture gains exceed design values. The work uses a channel-free Respireco recuperator with cyclic operation. First, the thermodynamic properties of the recuperator itself were checked, and then it was tested in a selected Polish primary school. The results show that this type of recuperators are able to provide correct indoor climatic conditions in lecture halls. The use of mechanical ventilation using a recuperator with a ceramic heat recovery caused the CO2 concentration in the room to drop by 50% during classes. However, PM2.5 concentration was maintained at a level three times lower than in a room without mechanical ventilation. It should therefore be concluded that the use of mechanical ventilation with recuperation not only reduces heating costs but also significantly improves air quality.

2020-01-01T00:00:00Z Frik, Anton Martinaitis, Vytautas Bielskus, Juozas https://etalpykla.vilniustech.lt/handle/123456789/154835 2024-09-05T09:26:20Z 2020-01-01T00:00:00Z

Energy conversion modes depending on the outdoor temperature for an air handling unit with a heat pump Frik, Anton; Martinaitis, Vytautas; Bielskus, Juozas Modern air handling units (AHU) are increasingly finding solutions in which the main energy transformers are an air heat pump (HP) and a heat recovery exchanger (HRE). The energy conversion modes of such devices are constantly changing in accordance with the constant change on the state of the outdoor air (temperature, humidity). Flexibility, being able to respond to ever-changing ambient air parameters, is an important feature of energy transformation component mode control. The overall seasonal efficiency of the air handling unit depends on this. In this work, a thermodynamic analysis of the characteristic energy transformations of the air handling unit is performed, linking the outdoor and ventilated indoor air and HP refrigerant states, flow rates and component loads. Such parametric analysis with respect to the changing outdoor air temperature allowed to clearly reveal, through various indicators, the influence of the individual components on the operating efficiency of the air handling unit. Combinations of parameters have been obtained that enable the selection of the optimal control concept for the energy conversion mode of the components in the air handling unit (component loads, fluids state parameters and flow rates) over a wide range of outdoor air temperatures.

2020-01-01T00:00:00Z Vilčeková, Silvia Harčárová, Katarína Moňoková, Andrea Krídlová Burdová, Eva https://etalpykla.vilniustech.lt/handle/123456789/154834 2024-09-05T09:24:51Z 2020-01-01T00:00:00Z

Life cycle assessment and short-term measurements of indoor environmental quality of a wooden family house Vilčeková, Silvia; Harčárová, Katarína; Moňoková, Andrea; Krídlová Burdová, Eva Nowadays, there is an increased trend in the construction of nearly zero energy buildings which can be also characterized as green buildings. Several studies confirm that wooden buildings fulfil these requirements. However, there is no detailed research related to the quality of the indoor environment in new wooden family houses. For this reason, this paper focuses on monitoring of the indoor environmental quality in a selected wooden family house. Shortterm measurements are aimed at investigation of physical parameters (air temperature, relative humidity, air velocity and noise) and chemical factors such as concentrations of particulate matters and CO2. At the same time, environmental impacts were also assessed for impact categories such as: global warming potential (GWP), ozone depletion potential (ODP) acidification potential (AP), eutrophication potential (EP), photochemical ozone creation potential (POCP) expressed as kilogram CO2eq, CFC11eq, SO2eq, PO4 3–eq and kilogram of C2H4eq within “Cradle to Grave” boundary by using the life cycle assessment (LCA) method. The main contribution of this study is demonstration that wooden buildings have substantial share in the reduction of environmental impacts. So far, results indicate that the design of wooden houses correspond with the increasing demands of occupants in terms of environmental, social and energy performance.

2020-01-01T00:00:00Z