Polish Climatic Conditions Research Articles

Solar Tracking System with New Hybrid Control in Energy Production Optimization from Photovoltaic Conversion for Polish Climatic Conditions

This paper presents a comparison of the 24-month production of electricity and momentary power by two photovoltaic systems with a nominal power of 1000 Wp each. The analyzed systems are connected to the power grid and operate independently: a fixed system with optimal all-year-round angular positioning and an astronomical-sensor-controlled dual-axis tracking system. The systems under consideration consist of PV modules with a unit electrical power of 200 Wp, and the production technology of those modules is the same. The tested systems were located on the building rooftop of the Faculty of Control, Robotics and Electrical Engineering of the Poznan University of Technology in Poland (Central Poland, 52°24.4152′ N, 16°55.7958′ E) at a height of 30 m above ground level. The measurements take into account the consumption of electricity by the actuators of the dual-axis positioning system. Increases in the produced electricity by 35.6% and 44.7% were observed for local climatic conditions during the first and second measuring years, respectively, when comparing the use of the dual-axis tracking system with the use of fixed units. Results show that the analyzed region of central Poland, represented by the city of Poznań, creates favorable climatic conditions for the use of astronomical-sensor spatial positioning systems for photovoltaic modules, also in the case of a significant share of diffuse solar radiation in the global value. These results may make the planning of solar tracking investments easier and help with the estimate calculations of the total investment return period and operational costs.

Examples and Concepts of Floating Architecture in the Face of Climate Change - The Example of Szczecin

The article presents the issues of the impact of climate change on the architecture of Baltic cities with the example of Szczecin. Although measures are being taken to prevent further warming, the scale of changes requires action in various areas, including urban planning. In the temperate climate of Poland, the projected temperature increase by the end of the 21st century will have been 2-4 degrees Celsius (according to the latest IPCC reports on the effects of global warming). Therefore, the sea level may rise by 60-120cm. The cities of the Baltic Sea region are facing a significant challenge. In the future, they will face a high intensity of extreme weather events and changes in precipitation levels. The rising sea level forces the search for an alternative way of building. One of the cities in Poland where changes will be experienced is Szczecin. Some positive effects of climate change will also appear, such as longer tourist and vegetation seasons in Poland of up to 4-6 months and an increase in the attractiveness of Polish tourist cities. What is more, the country must also be prepared to accommodate the larger population resulting from climate migration. The article presents examples of designs and developments of the floating architecture which can become inspiring in the face of climate change challenges. A discussion on the pros and cons of such solutions was conducted. The authors put forward a thesis that some architectural solutions may prove useful for the upcoming problem, but they require prior improvement and adaptation to the Polish climate and economic conditions.

Energetic and Ecologic Heat Pumps Evaluation in Poland

The purpose of the work is a comparison of indirect carbon dioxide emissions between the different heat pump types that operate in Polish climate conditions. The analysis embraces air-to-water heat pump, ground-to-water heat pump, water-to-water heat pump and water-to-water heat pump with separating heat exchanger in the selected towns one in each climatic zone in the country. The study starts from determining seasonal coefficient of performance in each location using heating degree days to estimate seasonal heat demand. Seasonal coefficient of performance values enable an assessment which kind of heat pump meets the European Union requirements in every location. Eventually, indirect CO2 emissions that is caused by electrical energy production, are estimated for every heat pump in each location. Ground-to-water heat pump and water-to-water heat pump satisfy these requirements in each climatic zone in Poland. Air-to-water heat pump would be an energetic and ecological viable on a condition that substantial changes were done in Polish electrical energy mix.

Energy Efficiency of a Solar Wall with Transparent Insulation in Polish Climatic Conditions

A numerical model of a solar wall (SW) with transparent insulation (TI) is proposed in this article. The model is based on the finite-difference method and thermal conductivity equation, with a heat source term for the absorber. Using this model, the energy efficiency of a solar wall with transparent insulation (SW-TI) with honeycomb insulation made of modified cellulose acetate was analyzed in the case of different climatic conditions prevailing in Poland, different orientations of the envelope, and different insulation thicknesses. Simulations were carried out throughout the whole heating period. Monthly energy balances and temperature distributions for the analyzed envelopes at individual moments of the heating period are the basic results of the simulations. It was found that the use of 108 and 88 mm thick insulation was the most recommended in the considered temperate climate. Placing transparent insulation on a wall with an eastern or western orientation caused the annual heat balance of the envelope to decrease by 24–31% in relation to the value of this balance in the case of a southern orientation. The monthly heat balances obtained using the proposed model give results consistent with the method of calculating heat gains for opaque building envelopes with transparent insulation included in the PN-EN ISO 13790:2008 standard.

Experimental studies of thermal performance of an evacuated tube heat pipe solar collector in Polish climatic conditions

This work presents the results of experimental studies on the energy performance of an evacuated solar collector, heat pipe type, consisting of 24 tubes, over the period of 2 months. The solar collector with a gross area of 3.9 m2 is part the solar hot water test system located in Lublin (Poland). The effect of the weather conditions and operating parameters on the thermal and exergy efficiencies of the evacuated tube solar collector has been defined. The solar irradiation per month for July amounted to 80 kWh/m2, and for August, it equalled 112.8 kWh/m2. The average thermal gain was found to be in July 163 W/m2 and in August 145 W/m2, respectively. For the considered study period, the average value of energy yield in the solar collector was obtained at the level of 4.28 MJ/(m2·d). The average monthly energy efficiencies of the solar collector in July and August were 45.3% and 32.9%, respectively, while the average monthly exergy efficiencies reached 2.62% and 2.15%, respectively. Increasing the wind speed to 0.86 m/s decreases the thermal efficiency and the exergy efficiency by 67% and 41%, respectively.

Stevia Rebaudiana Bertoni, a Source of High-Potency Natural Sweetener-Biochemical and Genetic Characterization.

Stevia rebaudiana is a natural sweetener herb that is increasingly used in herbal medicines in the food and cosmetics industries. Molecular methods can be combined with morphological techniques to identify stevia genotypes as a starting material to produce more reliable bioproducts. This study evaluated the level of the genetic and biochemical diversity in various stevia genotypes using HPLC (high performance liquid chromatography) analysis and random amplified polymorphic DNA (RAPD) markers. Stevia genotypes collected from different locations of the world showed clear variations at the biochemical and genetic level in Polish climate conditions. The influence of the genotypes on the content of steviol glycosides, antioxidants, phenols, flavonoids, and tannins was analyzed using phytochemical assays. Genotypes from Morocco, Poland, Egypt, and Nigeria can be defined as samples of higher quality compared to other genotypes analyzed in terms of the amount of steviol glycosides. Considering the rebaudioside A/stevioside ratio as a selection criterion, genotypes from Australia, China, India, and Pakistan should be considered to be valuable in terms of suitability for obtaining new varieties. The present results of RAPD marker analysis indicated differential banding pattern and considerable polymorphism among all ten stevia genotypes. Genotypes from Morocco, Egypt, Poland, Nigeria, China, and India, as genetically different, can be selected for further stevia breeding programs.

Potential of using greenery to reduce overheating of buildings in Polish climate conditions

The issue of overheating the buildings gives great opportunities for the use of greenery, that can affect the amount of passive solar gains through the glazed parts of façades. Restricting the access of the sunlight to the façades helps to reduce the energy usage for the cooling purposes, but, on the other hand, may cause reduction of solar gains in winter. The aim of the research is to determine the potential of using greenery to reduce energy demand of buildings by achieving the optimal balance between solar energy gains and losses in polish climate conditions.

Influence of double-cut harvest system on biomass yield, quality and biogas production from C4 perennial grasses

This study's aim was to determine the impact of two harvests per year on the yield, biomass quality, and suitability for ensiling and biogas production of cordgrass (Spartina pectinata Bosc ex Link), switchgrass (Panicum virgatum, var. Dacotah) and big bluestem (Andropogon gerardii, var. Bison). Grasses were harvested at the end of June (I harvest) and at the beginning of October (II harvest). Single harvest at the beginning of October was also conducted. Biomass from I and II harvest was ensiled and then subjected to anaerobic digestion. There were no differences between dry matter yield of investigated grasses from I and a single harvest, which indicated the validity of two harvests per year in order to increase biomass yield during a growing season. Double-cut harvest system had an effect on C/N ratio and lignin content decreasing in the biomass compared to a single harvest. Biomass from I and II harvest was suitable for ensiling. Double-cut harvest system did not influence on biogas yield from switchgrass and big bluestem. Cordgrass and big bluestem have been found to be better feedstock than switchgrass for biogas production in Polish climate conditions because they offered higher methane yield per hectare.

Investigating the use of moist aggregates in the production of low-temperature bituminous mixtures using foamed bitumen

The use of moist/wet aggregate fractions in the asphalt mixtures with reduced production and compaction temperatures (HWMA - Half Warm Mix Asphalt) with foamed bitumen is aimed at obtaining an additional foaming effect of the binder. The paper presents results of investigations on the possibility of producing the asphalt concrete for the upper layers of the road pavement at reduced technological temperatures utilizing fine wet aggregates and foamed asphalt in opposition to specific patented solutions. This modification of the production process was evaluated in the scope of moisture content in the 0/4 mm aggregates in terms of mixture compactibility using the gyratory compactor and the assessment of related physical and mechanical properties of the asphalt mixtures. The analysed moisture contents resulted in a final 1% and 3% water contents in the whole mineral mix. In order to assess the effect of the addition of wet aggregates on the properties of the mixture produced at the reduced temperature with foamed bitumen, three identical asphalt concrete AC 16 mixtures in terms of composition were used, hot-mix HMAREF and warm-mix WMAREF, with differences only in technological temperatures of the mix constituents during their preparation and mix compaction, the form of the binder (liquid in HMAREF mixture, foamed with water in WMAREF mixtures) and half-warm mix HWMA with foamed bitumen additionally utilizing a portion of fine wet aggregates in the blends. The conducted studies have shown that the presence of the wet aggregates in the mixtures with foamed bitumen had a significant impact on the air void contents in the samples formed in the gyratory compactor. In a mixture with foamed bitumen, produced and compacted at a reduced temperature (HWMA), an improvement in the compaction in relation to the reference mixture WMAREF was found. Based on the results of indirect tensile strength tests and analysis of the ITSR indices, it was found that the use of wet aggregates had major, significant effects on the mechanical properties of the samples subjected to water and frost susceptibility testing. The mixture produced with wet aggregates obtained indices for resistance to the moisture and frost damage which were unsatisfying for the upper bituminous pavement courses as for Polish climatic conditions (ITSR<70%). This result was attributed to inadequate the aggregate coating and reduced adhesion of the binder. It was stated that the mixtures resembling HWMA, produced with moist or wet aggregates at reduced technological temperatures can be utilized in Polish and similarly harsh climatic conditions in the lower pavement structural layers, mainly due to their reduced moisture and frost resistance. The application of the tested mixtures to the upper structural layer would require using special treatments, e.g. chemical additives, in order to improve the adhesion of asphalt to aggregate or raise the technological temperature (as for WMA blends) to increase the dynamics of water evaporation from the damp aggregates.

Influence of building airtightness on the internal thermal comfort and air quality in the single family house

The knowledge of the air exchange and building air-tightness is an indispensable source of information, both on the design and operation stage of the building use. Properly functioning ventilation system affects significantly internal thermal comfort and internal air quality. Infiltration of air determines the proper functioning of the gravitational ventilation, still the most commonly used system in Polish single-family housing. However, the most popular and easy to measure parameter: building airtightness (n50), does not specify the real air exchange in the actual climatic conditions. The real air flow rate may be determined with much more troublesome gas tracing method. Air flow rate, n, is in this method obtained from the decaying curve of gas concentration after injection of tracer gas into the building. This paper presents the results of the airtightness measurements conducted in a single family house with natural ventilation. Both, n50 parameter and building air flow rate n have been measured. The results of the measurements were used as a model calibration tool in the annual computational simulations carried out in the Design Builder program for the Polish climatic conditions. Based on these simulations the authors determined the influence of building airtightness on the internal thermal comfort and the potential scenario of its control.

Cooperation of a Horizontal Ground Heat Exchanger with a Ventilation Unit During Winter: A Case Study on Improving Building Energy Efficiency

Renewable energy sources have a significant impact on improving a building’s energy balance. These sources are increasingly used in modern construction. One such source is a ground air heat exchanger (earth-air heat exchanger – EAHX), which is used in a building’s mechanical ventilation system. This solution allows for the initial preparation of inlet air in a ventilation unit prior to the exhaust air energy recovery process (recuperation). As a result, the solution reduces the energy demand for the heating or cooling of rooms. This article expands upon a previous study on the possibilities of improving energy efficiency of a horizontal earth-air heat exchanger (EAHX) working in cooperation with a ventilation unit. This study adds to the knowledge gained in the previous study (Romańska-Zapała et al., 2017) performed during the summer of 2016. This previous study found that, in the summer, the continuous operation of these exchangers is not optimal; therefore, there is a need for dynamic control of the ventilation unit’s fresh air source. This is due to changes in the exchanger’s operating status between heating and cooling, as a result of external temperature fluctuations. The thesis statement of this previous paper emphasized that this relationship is not only appropriate on an annual basis for the transitional seasons (spring and autumn), but also on individual days during the potentially most favorable seasons of exchanger work (summer and winter). This article presents the results of in situ measurements of the horizontal, tubular ground air heat exchanger which supports building heating by preheating the inlet air of the cooperating ventilation unit in the winter season, in southern Polish climatic conditions. In particular, this article provides details on the experimental verification of the previous paper’s thesis regarding the possibility of sub-optimal performance of an EAHX exchanger subject to continuous operation during the winter season. The experiment in this paper was performed using a ventilation unit (intake – exhaust) connected to three independent fresh air sources: a direct external air intake located on the wall, and two air intakes located outside of the building that directs air into the pipes of two earth-air heat exchangers. This article illustrates how the exchanger’s work changes the ventilation unit’s inlet air temperature. For a majority of the experiment, the exchanger – ventilation unit system was working optimally. Therefore, the system did not require intervention of the control system. However, due to several temporary increases in outdoor temperature, the occasional cooling state operation of the EAHX exchanger was also recorded. Even before the occurrence of these undesirable states, an exchanger should be switched off and a bypass should be used to directly collect external air and reduce the unnecessary load of electric fan drives. Considering the results of this study, it can be concluded that in the winter, it is favorable to automatically control the selection of a ventilation unit’s fresh air source depending on external conditions. However, in the winter, the energy effect of the control is comparatively lower than in the summer.

A comparative study on electric and gas engine heat pump

The paper compares heat pumps driven by electric motors (EHP) with heat pumps driven by gas engines (GEHP). GEHPs are still a novelty on the Polish HVACR market - therefore, the subject of the study is to indicate whether in Polish climatic conditions their use is profitable. A thorough analysis of the energy consumption of selected devices was carried out due to the consumption of utilities needed for their propulsion and the related costs. This has been done by calculating seasonal efficiency coefficients and using an innovative method of comparative modifiers allowing for unification of the performance of EHP and GEHP pumps. The results obtained include average energy efficiency coefficients, operating costs and payback times. Discussion of the calculation results proved that under certain assumptions GEHP pumps may be competitive with EHP heat pumps due to the possibility of managing waste heat at high temperatures.

MULTI-VARIABLE OPTIMIZATION MODELS FOR BUILDING ENVELOPE DESIGN USING ENERGYPLUS SIMULATION AND METAHEURISTIC ALGORITHMS

Abstract The paper presents the method of optimal design of the building envelope. The influence of four types of windows, their size, building orientation, insulation of external walls, ceiling to unheated attic and ground floor on the life cycle costs in a single-family building in Polish climate conditions is analyzed. The optimization procedure is developed by means of the coupling between MATLAB and EnergyPlus. The results using three metaheuristic methods: genetic algorithms, particle swarm optimization, and algorithm based on teaching and learning are compared. The analyses have shown the possibility of reducing the life cycle costs through the optimal selection of the building structure. The high initial investment (above the required standard) pays off in the long run when using a building.

Equivalent temperature for design of asphalt pavements in Poland

The paper presents application of equivalent temperature for design of asphalt pavements. The calculation methods of equivalent temperature: the Shell method, the French method, the methods that use the AASHTO and the Asphalt Institute fatigue criteria were presented. The results of calculations of equivalent temperature for Polish climatic conditions were presented and discussed. It was shown that different asphalt pavement design methods and utilization of Polish climatic data resulted in various calculated values of equivalent temperature that could be used in the design process.

Analysis of temperature gradient in concrete pavement

The paper presents the results of experimental research that is the continuation of the research conducted as a part of a Ph.D. dissertation. The experimental research consisted in measuring the temperature at various depths inside a concrete slab, including its surface, and measuring the air temperature. The temperature distribution was measured on a concrete slab with dimensions similar to real road slab dimensions. The aim of the research was to determine the temperature gradient in the concrete slab in Polish climatic conditions and to verify the available analytical methods. Keywords: temperature gradient, concrete pavement, thermal stress in concrete pavement.

Analysis of the Possibilities of Using a Heat Pump for Greenhouse Heating in Polish Climatic Conditions—A Case Study

This article presents an analysis of selecting a seasonal heating system for an existing greenhouse. The analyzed object is located in Poland near Wroclaw, where summer flowers are grown. Appropriate thermal conditions must be ensured continuously for four heating months. The primary source of heat in the examined flower greenhouse was a coal-fired furnace. The analysis presented in the article shows a method of thermal balancing the object, determining heat demands in the analyzed period using the experiment plan, and also selecting a new heating system in the form of a heat pump. The analysis of the operation of the heating system was performed for air and ground source heat pumps to determine the profitability of their application in Polish climatic conditions. An economic analysis was also included and the investment impact on pollution emissions was calculated.

Apple rootstock trials at Warsaw University of Life Sciences-SGGW, Poland

valuation of 22 dwarfing and semi-dwarfing apple rootstocks for several scion cultivars was conducted on fertile soil in the years 1995–2010. It was found that most of the new rootstocks performed similarly to M.9 EMLA with respect to vigour, yield, cropping efficiency and fruit mass. These rootstocks would not be, therefore, a good replacement for M.9 in Polish climatic conditions. The most promising rootstock was B 9 and some of its derivatives, e.g., B 146, B 396, P 59 and P 60. However, their suitability may be limited to particular cultivars grown under similar soil conditions.

Natural asphalt modified binders used for high stiffness modulus asphalt concrete

This paper presents a set of test results supporting the possibility of replacing, in Polish climate conditions, hard road 20/30 penetration grade bitumen used in the binder course and/or base course made of high stiffness modulus asphalt concrete with binders comprising of 35/50 or 50/70 penetration grade bitumens and additives in the form of natural Gilsonite or Trinidad Epuré asphalts. For the purpose of comparing the properties of the discussed asphalt binders, values of the Performance Grade have been determined according to the American Superpave system criteria.

Analysis of a micro photovoltaic/thermal – PV/T system operation in moderate climate

The paper analyses the possibility of application of PV/T systems in moderate climate conditions. Experimental part of research studies has been developed in Patras, Greece, in October–November. In that time climatic conditions in Greece are similar to summer (warmest) weather conditions in Poland. Some aspects of Polish climatic conditions, especially of solar radiation availability are presented. The liquid single glazed PV/T module has been selected for consideration as the most suitable for described climatic conditions. Experimental outdoor stand with such PV/T module has been designed and constructed to determine its energy performance. A mathematical model of the photovoltaic/thermal solar system operation is presented. Existing formula for determination of the PV/T temperature during its operation has been validated by experimental studies. As a result the correction - design factor has been introduced to the formula. It helps to take into account the design (number of covers) of the PV/T module, when its energy performance and operation are determined through simulation studies. Simulation studies of the dynamics of a microscale PV/T system supplying energy (electricity and heat to Domestic Hot Water system) to a standard single-family house has been performed using own numerical code. Selected results of simulation studies of the operation of different cases (sizes) of PV/T systems are described. Simulation studies of operation of the PV/T systems in micro scale application in high latitude countries show, that for 2 months of a year, in December and January, more electrical than thermal energy is generated by the PV/T system. In summer problems with too high temperature of the working fluid of the PV/T module can occur. As a result, the electrical efficiency decreases. In Polish climatic conditions a PV/T system should be provided with a continuous heat removal system to assure efficient operation of the system.

Radiative cooling in polish climatic conditions

Ecological, natural ways of obtaining energy for building cooling are becoming more and more popular around the world. Reducing energy demand and increasing the renewable energy use can be achieved for example by using radiative cooling. Depending on climatic conditions and the type of cooling system, radiative cooling is able to cover a part of refrigeration needs. The document presents the possible energy yield from using radiative cooling in systems operating at respective parameters in polish climatic conditions.