Browsing by Author "Ehrenwirth, Mathias"
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Item Open Access Effect of argon concentration on thermal efficiency of gas-filled insulating glass flat-plate collectors(Elsevier, 2023-05-02) Summ, Thorsten; Ehrenwirth, Mathias; Trinkl, Christoph; Zörner, Wilfried; Pischow, Kaj; Greenough, Richard; Oyinlola, M. A.Insulating glass flat-plate collectors can save cost by being produced quickly and automatically in insulated glass production facilities, and they can be filled with argon to reduce heat loss. During its lifetime, the collector is likely to lose argon because of gradual material degradation of the sealing. However, information on the influence of the argon concentration on the collector efficiency is limited. Therefore, the objective of this research work was to analyse this effect. A theoretical material property calculation of argon-air mixtures was carried out to determine the convective losses with variable argon concentrations. Thermal collector performance was measured experimentally using an outdoor solar tracker test rig. The results strongly suggest, that the influence of argon concentration on both the convective losses and the thermal efficiency is non-linear. The measurements revealed that an argon concentration of 90 % can increase average thermal performance by percentage points. An increase in argon concentration from 0 % to 50 % has almost twice the effect on average thermal efficiency as an increase from 50 % to 90 %. Concluding from these results, an argon leakage threshold of 2.5 percentage points per year is proposed to avoid disproportionate loss of efficiency over time.Item Open Access The Energy Situation in Central Asia: A Comprehensive Energy Review Focusing on Rural Areas(MDPI, 2021-05-13) Greenough, Richard; Ehrenwirth, Mathias; Trinkl, Christoph; Zorner, Wilfred; Mehta, KedarThe northern part of the globe is dominated by industrialisation and is well-developed. For many years, the southern part of the world (South Asia, Africa etc.) has been a target of research concentrating on access to energy (mainly electricity) in rural regions. However, the Central Asian region has not been a focus of energy research compared to South East Asia and Africa. Despite plentiful domestically available energy resources, the energy supply in Central Asia is very unevenly distributed between urban and rural areas. Almost half of the total population of Central Asia lives in rural areas and there is a lack of access to modern energy services to meet primary needs. To analyse the energy situation (i.e., electricity, heating, hot water consumption, cooking, etc.) in rural Central Asia, this paper reviews residential energy consumption trends in rural Central Asian regions as compared to urban areas. Furthermore, the paper illustrates the potential of renewable energies in Central Asia. To perform the study, a qualitative comparative analysis was conducted based on a literature review, data, and statistical information. In summary, the presented article discusses the rural energy situation analytically and provides in-depth insights of Central Asian energy infrastructure.Item Open Access Impact of Locally Available Thermal Insulation Structures on Space Heating Demand of High-altitude Rural Buildings: A Case Study of Kyrgyzstan(International Solar Energy Society, 2020-09-01) Mehta, Kedar; Ehrenwirth, Mathias; Trinkl, Christoph; Greenough, RickKyrgyzstan is a high-altitude mountainous country situated in a cold climatic zone. The age of the residential buildings, poor housing conditions and the absence of proper thermal insulation result in high heat demand and low thermal comfort in Kyrgyz houses. To maintain thermal comfort, the rural residents use traditional heating stoves to burn solid fuels during the winter months. Overconsumption of natural resources is mainly responsible for deforestation, as well as indoor and outdoor air pollution. Implementation of building thermal insulation is considered as one of the potential measures for energy conservation. In regards to this, the presented research proposes the various thermal insulation structures developed from the locally available natural materials. Further to this, it identifies the effectiveness of various thermal insulation structures on the annual space heating demand of a highaltitude single-family house located in rural Kyrgyzstan. The results show that the insulation parameter helps to save a considerable amount of space heating demand by up to 30 % in the case of existing houses and up to 70 % for newly built houses in rural Kyrgyzstan.Item Open Access A Parametric Study on the Feasibility of Solar-thermal Space Heating and Hot Water Preparation under Cold Climates in Central Asian Rural Areas(International Solar Energy Society, 2020-09-01) Mehta, Kedar; Ehrenwirth, Mathias; Trinkl, Christoph; Zorner, Wilfred; Greenough, RickA large part of the Kyrgyz territory is covered by mountain ranges which result in extremely cold winter periods. The cold climatic conditions of Kyrgyzstan define heating as an essential need for Kyrgyz people. The majority of the residential buildings are constructed with poor thermal insulation or none at all, which yields high energy consumption in buildings to maintain thermal comfort. Especially in rural households, the heat demand is usually covered by solid fuels (i.e. wood, branches, coal and other solid fuels) burned in traditional stoves / boilers. The intensive use of solid fuels contributes to indoor and outdoor air pollution. Hence, there is a substantial need to provide sustainable and adequate heating services for residential buildings, particularly for the rural population. In response to this, the presented research article describes an investigation of solar resources to support space heating and domestic hot water preparation for single-family homes in rural Kyrgyzstan. Besides that, it identifies the thermal performance of typical single-family houses by considering local boundary conditions such as cold climate, highaltitude and routine behavior of the inhabitants. The determination of fuel savings by implementing solar-thermal domestic heating systems helps to explain the positive impacts on the environment. The investigation shows a significant solar-thermal energy potential available for domestic space heating and hot water preparation in Kyrgyzstan.Item Metadata only Towards maximum cost-effectiveness: multi-objective design optimisation of insulating glass flat-plate collectors(Elsevier, 2024-10-11) Summ, Thorsten; Oyinlola, M. A.; Khattak, Sanober; Ehrenwirth, Mathias; Trinkl, Christoph; Zörner, WilfriedA significant challenge in the advancement of solar thermal heating systems lies in the unexplored techno-economic potential of insulating glass flat-plate collectors. These collectors are constructed in accordance with the specifications of standard insulating glass units and have emerged over the past decade as a promising design concept for enhancing the cost-effectiveness of solar thermal systems. However, substantial findings regarding the techno-economic viability of their production are still pending. The aim of this paper is to optimise insulating glass collector designs for solar district heating applications by identifying key design parameters that maximise cost-effectiveness. This study employed a five-stage methodology. It included thermo-hydraulic collector modelling using MATLAB/Simscape and the CARNOT Toolbox. The model was validated against experimental performance tests. A Latin hypercube computational design with 250,000 samples was set up to train supervised machine learning metamodels and perform a multi-objective optimisation using an elitist genetic algorithm. The study identified the argon concentration, collector length, and width as critical parameters influencing efficiency. Larger, thinner collectors demonstrated superior performance due to reduced convective losses and increased aperture-to-surface ratios. The optimisation revealed that the insulating glass collectors could achieve a 7.7 percentage point increase in efficiency, a 19.4 % reduction in material cost, and a 14.5 % decrease in weight compared to market-available flat-plate collectors. However, the direct economic comparison was not considered strong in evidence due to a lack of economic data from technology providers. The most cost-effective designs featured an argon concentration of 99 %, sealing thickness of 31.2 mm, and a glazing thickness of 4.1 mm, and 4.5 mm, while collector length and width varied more significantly. The research findings indicate the techno-economic potential of insulating glass collectors, demonstrating their ability to outperform conventional flat-plate collectors in terms of cost-effectiveness and efficiency. Future studies should focus on producing and testing larger modules and incorporating production costs to fully realise their potential for solar district heating applications. This study provides valuable guidelines for IGU designers and producers aiming to develop cost-effective and efficient solar thermal collectors for district heating systems.