Issue 4/2019

This paper focuses on active ceiling soffits which provide heating and cooling especially in office buildings. A particular disadvantage of these systems is their low performance, when they work in cooling mode. The cooling capacity can be increased by partially cutting the soffit or by completely changing the geometry (ceiling baffles). This paper is dedicated to the suspended ceiling geometry effect on its cooling performance. Cooling performance of individual geometric arrangements is evaluated using CFD simulations. These simulations are also complemented by measurements on a real soffit installed in the laboratory of the university’s research centre (UCEEB) in its climate chamber.

A fan chamber is an important part of any modular air-conditioning unit. Its interior design has a significant impact on both the energy efficiency of the entire unit and the generated noise. Air flow analysis and optimization of fan chamber is a complex issue, difficult to be addressed without the use of computational fluid mechanics (CFD). The paper demonstrates the current features of ANSYS software in modelling and simulation of the ALTEKO Tango 4 fan chamber equipped with a radial fan with an unhoused backward curved impeller. It describes the import of detailed geometry from CAD software and its necessary simplification, meshing of the model and CFD simulations involving the fan impeller rotation approximation. The presented work was a part of a project supported by the EU under the Operational Program Enterprise and Innovation for Competitiveness. Its results were used for the development of a new fan chamber ALTEKO Alton.

This paper deals with an office building project where one part of the building was changed to a clinic as a project modification before its finalization. However, the medical offices are in a noise protected indoor space where the hygienic noise limits are stricter. This leads to the higher standards of the facade, than originally designed. Due to traffic noise, there is a high noise level in the area for the office building, so it was necessary to develop the simulation of the outdoor noise and then to verify the sound insulation of the fully glazed facade or develop potential improvements in the construction. The mock-up was built for the verification of the model and the final results were confirmed by measurements for the bu ildings approval.

The aim of the paper is the analysis of heat flux and temperature distribution in the building structure between the ice rink cooling register and the subsoil tempering layer under the ice rink of an ice arena. The source of heat for tempering is the cooling circuit waste heat. Data from in situ measurements were used in the article; the ice temperature, tempering fluid temperature and temperature of the subsoil sensor were recorded by the local measurement and control system. The recorded values were used to calibrate the model in CalA. The computational model uses an unsteady 2D simulation of thermal behaviour of the ice rink with subsoil, including phase change of ice and thermal radiation between the ice surface and the roof. From the results of the modelled building structure it is apparent that part of the heat flux from the tempering layer passes into the cooling layer and thus increases the thermal load removed by th e cooling system.

The paper introduces potential benefit of unglazed photovoltaic-thermal collectors (PVT) during night operation, when the collector can be cooled down by convection and radiation towards the sky. Simulation analysis of the cooling gains of unglazed PVT collectors have been carried out. Mathematical model of unglazed PVT collector was experimentally validated and implemented into TRNSYS. Theoretical calculated cooling gain for commercially available unglazed PVT collectors has been compared with experimental results from testing. Developed model was used for simulation analysis of different PVT collector designs for climate conditions of Arabian Peninsula. Moreover, simulation analyses of the cooling performance for different European climate have been performed. While best of tested unglazed PVT collectors can achieve average specific cooling power around 110 W/m2 at chilled water temperature 20 °C in the climate conditions of central and northern Europe, in the climate conditions of south Europe these unglazed PVT collectors achieve not more than 38 W/m2 during summer season (June-August).

Increasing demands on adequate quality of working environment in heavy industry and on the efficiency of technical equipment are leading to optimization of ventilation systems in industrial plants. Considering the complexity of the issue, the use of computational Fluid Dynamics (CFD) can be beneficial when analysing existing systems and designing new technical solutions. The paper describes the analysis of the existing ventilation system of the industrial steel processing shop of US Steel Košice. It is based on two previous experimental and computational studies. It describes the modification and necessary simplification of the geometric model of the analysed facility, creation of the numerical mesh and CFD simulation focused on the efficiency of the ventilation system at various volumetric flows. The boundary conditions of the simulation and its setting are presented as well, including the method of simulating the spreading of pollutants from the surface of the melted steel during its alloying with CaSi. The optimal setting of the ventilation system and the possibilities of its further optimization in order to increase its efficienc y are described on the basis of the obtained results.

The aim of the research work was the simulation of changes in an existing building stock. The model includes the description of existing stock by means of groups of buildings with similar energy consumption. This approach is the contribution for the simulation methods because the model uses arrays for the description of buildings stocks. This approach increases the accuracy of the calculations. The key method used for the solution is systems dynamics. The model stock element is the stock of buildings represented by the floor area. The output parameter is the amount of refurbished buildings. There are presented three case studies for restricted financial resources. These restrictions create the space for the solution that allows the energy consumption decreasing to a certain level.

The world data center energy consumption has been growing rapidly and currently is estimated at 1,7–2,2% of the world-wide electricity consumption. Achieving sustainability in this sector calls for development new energy efficient strategies and measures. Current research deals with development of holistic operation i.e. operation, where all essential processes such as data processing, cooling and power delivery and supply (including renewable energy sources) are optimized a coordinated. Testing of modern operational strategies, which is necessary for development and commissioning, is not possible during the regular operation due to the risk of limitation of the services or outage of the data center operation. Any outage of the data center is related with financial and reputation losses. Therefore, the testing is extremely limited. Alternatively, building energy simulation may offer “safe” testing environment for advanced control algorithms and accelerate their implementation in practice. This paper describes a novel workflow for testing of modern control algorithm and new a pplication of building energ y simulation of da ta center.