New method for the design of radiant floor cooling systems with solar radiation

Impacts of solar shortwave radiation are not taken into account in the standardized design methods in the current radiant system design guidelines. Therefore, the current methods are not applicable for cases where incident solar is significant. The goals of this study are to: 1) use dynamic simulation tools to investigate the impacts of solar radiation on floor cooling capacity, and 2) develop a new simplified method to calculate radiant floor cooling capacity when direct solar radiation is present. We used EnergyPlus to assess the impacts of solar for different design conditions. The simulation results showed that the actual cooling capacities are in average 1.44 times higher than the values calculated with the ISO 11855 method, and 1.2 times higher than the ASHRAE method. A simplified regression model is developed to improve the predictability of ISO methods. The new model calculates the increased capacity as a function of the zone transmitted solar and the characteristic temperature difference between the hydronic loop and room operative temperature

Heterogeneity of Japanese proper adverbs in various theoretical approaches

W niniejszej pracy przeanalizowano w różnych ujęciach teoretycznych japońską część mowy zwaną najczęściej przysłówkiem. Praca podzielona jest na trzy rozdziały.Rozdział pierwszy poświęcony jest problemowi definicji przysłówka jako części mowy zarówno w języku japońskim, jak i ogólnie w językoznawstwie. Autor przedstawia kryteria, na podstawie których klasyfikował będzie leksemy do adwerbiów właściwych.W rozdziale drugim, będącym podstawą stawianej tezy, autor wymienia z przykładami liczne zjawiska językowe towarzyszące leksemom, które zdefiniował jako adwerbia właściwe.Celem ostatniego rozdziału jest uzasadnienie tytułowej, pozornie banalnej, tezy i uzupełnienie jej o pewne spostrzeżenia pragmatyczno-lingwistyczne, a także glottodydaktyczne.In this paper author analyses Japanese part of speech called adverb in various theoretical approaches. The paper consists of three chapters. First chapter is devoted to the problem of adverbs definition, both as Japanese part of speech and as part of speech in linguistics generally. Author presents criteria according to which he classifies lexemes to the group of “proper adverbs”.In the second chapter, which is a ground for the thesis, author lists many linguistic processes that follow lexemes described as proper adverbs. The purpose of the third chapter is validation of the seemingly trivial thesis, and addition of some remarks regarding pragmatics and glottodidactics

The New Method of Regulation of Centrifugal Fan

The paper will present new concept of centrifugal fan regulation with use of variable blade length system. Higher demands regarding low energy consuming devices do not omit fan what is underlined by internal regulations (e.g. EU Regulation 1253/2014). Regulation of fan is required in each system when constant value of flow and/or pressure cannot be ensured. Application of frequency inventers seems to be the most efficient method of regulation in case of centrifugal fan but has also some drawbacks. It requires additional power supply infrastructure. If fan is larger, costs of whole system increases. In case of large fans this costs are very high and change of rotational seed causes problem, since high inertia forces due to large rotating mass exist. Also, what is sometimes forgotten, costs of reactive power in such cases are very important from economical point of view. Alternatively, especially in case of larger centrifugal fans, implementation of fan with variable geometry can be solution ensuring operation in wider range with the highest possible efficiency. The concept described in the work is based on fan with variable blade length. Change of blade length causes change of impeller diameter and as a result flow characteristic of fan. In the article analytical description of such fan will be presented. What is more result of tests on real object with new solution will be presented to show fan performance curves within whole range of regulation. As showed currently done analytical calculations and CFD calculations, such solution can be an alternative to centrifugal fan with rotating end part of blades as well. Even if many difficulties exist in case of application of such system, this solution does not require additional costly power supply components and seems to be reasonable for big fans

Usage of modal test in verification of numerical model

Tuning of the numerical model is very important step during designing process. Correctly tuned model ensures proper evaluation of dynamic characteristics of vibrating object. This paper presets comparison of experimental modal analysis and theoretical numerical modal test of axial fan casing. Thanks to properly tuned model, it was possible to receive results of the numerical simulations similar to real test

Estimating the Remaining Operating Time of Mining Headframe with Consideration of Its Current Technical Condition

AbstractThe condition of headframes in underground mines has a substantial effect on the proper operation and safety of hoisting equipment. One of the potential problems that might occur during operation is the tilting of these structures, which can lead to difficulties in operation and, in extreme cases, to failures. The paper presents an original method of evaluating the technical condition of headframes, estimating the remaining operating time and finding the causes of irregularities in the operation of this kind of structures. To show this, a series of experimental studies and structural analyses were conducted on a model headframe. Based on experimental tests and numerical calculations, the operational safety of the structure was established along with limit values of operational parameters and possible preventative measures were proposed

Badania drgań maszyn wirnikowych w stanach ustalonych oraz nieustalonych na przykładzie wentylatorów promieniowych dużych średnic

Problem występowania stanów nieustalonych maszyn obrotowych jest powszechnie spotykany. Pojawia się on głównie podczas rozruchu i wywołany jest „przechodzeniem” przez prędkość krytyczną, która wzbudza drgania obiektu w bardzo szerokim zakresie. Ponadto problemy z drganiami maszyn obrotowych wywoływane są przez takie czynniki jak niewyważenie, niewyosiowanie, defekty łożysk i wiele innych. W pracy przedstawiono wyniki badań drgań zarówno w stanach ustalonych jak i nieustalonych przykładowych wentylatorów promieniowych. Za pomocą widm STFT przeanalizowano zarejestrowane przebiegi drgań niestacjonarnych. Dzięki temu możliwe było zidentyfikowanie głównych parametrów mających wpływ na poziom drgań podczas rozruchu oraz pracy normalnej. Badania przeprowadzono na czterech obiektach, co umożliwiło dodatkowe porównanie i wyciągnięcie wniosków odnośnie parametrów eksploatacyjnych całego układu przepływowego.The existence of unsteady states of rotary machines is a common problem. It occurs mainly during the machine start-up and is caused by “passing through” the critical velocity, which activates large scale object vibrations. Moreover, rotary machines vibrations problems are caused by faults such as unbalance, misalignment, bearing defects and others. The paper presents the results of tests of sample centrifugal fans vibrations, both in steady and unsteady states. The recorded time traces of non-stationary vibrations were analyzed with the STFT spectrum. This method allowed to identify main parameters influencing the level of vibrations during the start-up and regular operation of the machine. The tests were performed on four machines, which enabled an additional comparison of operational parameters of the whole flow system

Challenges in the design of a new centrifugal fan with variable impeller geometry

This article presents a description of design work for newly created centrifugal fans. This was done based on the example of an innovative solution that uses a change in impeller geometry. In the described solution, this is achieved by shortening and lengthening the impeller blades. The development of a technical solution with such properties requires a change of approach in the design process compared with classic solutions. Therefore, the following text describes this process from the concept stage to demonstrator tests. The principle of operation of such a solution is presented and the assumptions made based on analytical calculations are also described. The text also shows a 3D model of the centrifugal fan with variable impeller geometry, made with the help of computer aided design (CAD) tools. In the further part, numerical calculations were made on its basis. The finite element method (FEM) calculation made it possible to verify the structural strength of the project and its modal properties as well as to verify flow parameters, thanks to the use of computational fluid dynamics (CFD) calculations. The next step describes the procedure for testing centrifugal fans with variable rotor geometry, which is different from that of fans without this feature. The next part presents the results of research from the tests carried out

Evaluation of centrifugal fan impeller dynamic states in case of two different discrete models

Problem oceny stanów dynamicznych wirników wentylatorów jest możliwy do rozwiązania z wykorzystaniem metod numerycznych. W artykule przedstawiono porównanie wyników analizy modalnej metodą elementów skończonych, dwóch modeli wirnika wentylatora promieniowego: modelu powłokowego oraz objętościowego. Uzyskane wyniki wskazują, że poprawne przygotowanie modelu obliczeniowego skutkuje uzyskaniem analogicznych wyników w obu przypadkach.Preliminary evaluation of dynamic states in case of turbo machines is currently solved with use of numerical methods. In the article comparison of two models is presented. First model of impeller was discretized with use of shell elements and second with solid elements. For both models modal analysis was conducted. Thanks to received results comparison of both model was carried out. It should be stated that properly prepared models result in small differences in case of values of natural frequencies. On the other hand mode shapes can be transposed what was observed in case of third and fourth mode shapes

Optimization of gas flow streams with the use of numerical and experimental investigations

Częstym problemem w zakładach przemysłowych jest niewłaściwy przepływ energii cieplnej przenoszonej przez gazy procesowe wykorzystywane do suszenia materiałów. Rozwiązanie takiego problemu przez obliczenia teoretyczne potencjalnego rozkładu przepływu gazów jest często wystarczające, ponieważ rzeczywiste warunki eksploatacyjne mogą być złożone pod względem wahań ciśnienia, złożoności układu, zmian procesu itp. Artykuł opisuje bardziej dokładne podejście do problemu, na przykładzie problemu dotyczącego niewłaściwego rozkładu przepływów gazu w układzie mielenia i suszenie w cementowni. łączącego pomiar procesów na miejscu i dystrybucji przepływu modelowanie. Wykorzystane są badania eksperymentalne procesów przepływowych i modele oraz symulacje numeryczne odwzorowujące te procesy.Frequent problem in industrial facilities is improper distribution of thermal energy carried by the process gasses for the purposes of drying. Solving this by simple theoretical calculations of potential gasses distribution is not sufficient as real exploitation conditions may be complex in terms of pressure variations, compound ductworks, process variations etc. The article describes reliable approach and a solution of improper gas flow distribution in grinding/drying facility in a cement plant combining process measurement on-site and modeling flow distribution