Issue 3/2024

The paper presents a testbed design for advanced testing of heat pumps using the Hardware-in-the-Loop method. The architecture of the testbed is described in terms of both hardware and software parts and the data streams are illustrated. The control quality of the emulators and the climate chamber of the testbed are discussed using sample testbed test records.

The flow of air around natural heat sources and the thermal plumes associated with it is a complex issue that is difficult to solve without the use of an experiment or numerical simulations. In many cases, heat sources and their thermal plumes can have a significant effect on the overall quality of the indoor environment, which is why it is important to deal with them in the field of environmental engineering. The contribution is targeting the mutual comparison of thermal plumes around three models of human simulators with different complexity of geometry. The paper describes preparation of the models, the creation of a computational mesh with a detailed description of the boundary layer modelling and the settings of the simulations. All simulations were solved using Computational Fluid Dynamics (CFD) in the AN SYS Fluent software. The goal is to evaluate the effect of simplifying the geometry of the human simulator on the thermal plume rising above it and to determine the appropriateness or inappropriateness of using the given simplified model for further similar numerical studies and experiments.

As a result of the manufacturing, use and remediation of materials containing asbestos and inorganic fibres, it is becoming increasingly important to measure the concentration of these fibres in indoor air. Due to the use of various construction elements containing these fibres, it is necessary to measure their levels in the indoor environment as part of a site survey or to determine any necessary remediation measures and to evaluate their effectiveness. The respective regulations place great requirements on remediation and measurement techniques. For this reason, different fibre sampling methods based on the collection of particles from the air on a porous capillary membrane filter have been evaluated. The concentration of fibres in the air is determined on the basis of the counted number of fibres, the filter area and the volume of sampled air. Accredited supervision on remediation works is an essential part of any renovation of buildings in which construction elements containing fibres ha ve been used.

The rules for the billing of heating costs have been changed by an amendment to Decree Nr. 269/2015 Coll. The decree will now take into account the quality of the building envelope through the energy performance of the building. The change to the billing rules is based on simulation calculations that modelled different operating scenarios for two apartment buildings.

The paper discusses the possibility of using the bypass dampers of a rotary regenerative heat exchanger during the year and quantifies the potential energy savings associated with bypassing the pressure loss of the exchanger. For the purpose of the analysis, a prototype heat exchanger with a heat wheel diameter of 1000 mm and bypass dampers with a diameter of 200 mm was designed and manufactured. The exchanger was subjected to experimental investigations to determine its behaviour. The pressure loss of the exchanger as a function of air flow rate was measured, as well as the pressure loss for three nominal air flow rates as a function of the bypass damper opening. The measurements indicated that the proposed design of the heat exchanger allows a reduction of the pressure loss of the exchanger by up to 49 % compared to the original value. On the basis of the measurement, an analysis of the potential electrical energy savings for the fan drive was carried out for the c limatic conditions of Central Europe.

The global focus on reducing carbon emissions in the building sector has led to the demand for a detailed analysis of the environmental impacts throughout the entire building life cycle. The World Green Building Council (WGBC ) estimates that the building sector accounts for 39 % of global carbon emissions. The environmental impact of building interior technical systems has rarely been studied in detail. Most published studies rely on assumptions and rule-based methods. However, for a detailed life-cycle assessment of the whole building, it is necessary to also analyse the building technical systems, whose impact can be significant (e.g. the carbon impact of HVAC systems ranges from 15 to 36 % of the total impact of office b uildings).