Issue 7-8/2022

Keywords: heat load, thermal inertia, temperature variability

Abstract
A specific feature of district heating systems is the fact that the heat load of the system is highly variable through the year. The heat load diagram is used to analyze this variability with multiple applications. The basis for the preparation of the load diagram is the variability of the outside air temperature, characteristic for the location of the object for which the diagram is prepared. The methodology of drawing up the diagram assumes that the heat loss for heating and ventilation is proportional to the temperature difference between internal and external air at any time, ignoring the thermal inertia of building partitions. In the presented article, an analysis of the influence of thermal inertia of partitions on the thermal loads’ variability during a year was carried out, in comparison with the load diagram used so far. The calculation methodology developed earlier was used to determine the thermal inertia. As a result, a significant difference was demonstrated between the theoretical and real course of the thermal load diagram. The results were confirmed by examples of changes in heat consumption in real buildings.

Keywords: absorption chillers, combined Heat and Power, trigeneration, energy efficiency

Abstract
Increasingly higher requirements of energy efficiency of devices and installations make it necessary to use solutions aimed at minimizing energy consumption and reducing environmental pollution in the form of emissions of harmful substances or waste resulting from the process of burning solid fuels. The answer to such needs are modern solutions based on high-efficiency devices, as well as solutions that allow the use of waste heat. And all this is used in order to protect the environment and at the same time use energy and heat power in the most efficient way. Therefore, the improvement of energy efficiency use and energy production is needed as well as promotion of renewable energy use leading to reduce the consumption of traditional energy carriers. In this thesis an assessment of the absorption chiller performance is presented. The paper presents an overview of combined heating, cooling and power sources (called trigeneration or CHCP) considering the impact of changing the source of cold on the operation of the entire system. The analysis was carried out on the basis of own studies on the change of the entire system from an absorption chiller to a compressor chiller. The impact of this change on the operation of the entire system and the investment and operating costs incurred were also analyzed. The analysis of the benefits associated with the possibility of producing cold by an absorption chiller operating for the air conditioning needs of a hospital building was also carried out.

Keywords: forecast control, forecasting heat consumption, building energy model, control of heating, energy efficiency in existing buildings, smart buildings

Abstract
One of the possibilities to increase the energy efficiency of heating systems in existing buildings is the use of forecast control. However, there is still no simple and easy-to-apply method for forecasting control taking into account internal (user influence) and external (weather conditions) factors. Therefore, this article presents the second part of information on the method of forecast control of heating systems, which is easy to apply in existing buildings. In particular, the method of taking into account the preferences of users in the form of an equivalent indoor temperature and the method of implementation of forecast control in the building were presented. It was found that the use of forecast control of heating system may allow for energy savings at the level of over 10% (without reducing thermal comfort in heated rooms), which, with the simple payback time (about 1 heating season), makes this solution one of the basic methods for increasing energy efficiency in existing and new buildings.

Keywords: econometric modeling, heating, digitization, energy, process control

Abstract
The vision of implementing the next stage of green transformation in the form of the negotiated package “fit for 55” raises concerns of representatives of the energy and heating industry in Poland. These concerns are mainly related to the scale of investment challenges and the costs already incurred under the CO2 emission allowance trading system, i.e. the EU ETS. Russia’s invasion of Ukraine has revised the current directions of the policy pursued as part of the transformation that is being carried out to switch from fossil fuels to renewable energy sources, with the priority of gas as a transitional fuel. Efficiency has again become the most important factor of transformation, which is significantly supported by the digitization of energy management at every level. Starting from minimizing the use of primary energy at the generation stage, through transmission and final consumption. Efficiency thanks to the use of digital tools of process decision optimization models, which also aim at economic optimization, should reduce energy costs throughout the entire life chain. The article presents examples of the implementation of econometric models for programming network operation, which, supplemented with elements of artificial intelligence using an updated database, can be used in various spheres of process and business decision-making. Digital analysis and an early warning system using this analysis improves the work efficiency and communication of the systems. Heating companies, largely responsible for the success of “fit for 55”, now have a lot of data measured in the processes of energy production and supply, but they do not always fully use these resources. Meanwhile, effective digitization, aimed at reducing energy consumption, does not mean the measurement and recording itself, but the purposeful analysis of the data set for modeling the process and formulating recommendations for the right decision.

Keywords: turbine plants, dispatch pressure, district heating network

Abstract
This paper describes the way of development of turbine installations used to stabilise the disposable pressure in the district heating network belonging to Municipal Thermal Energy Enterprise S.A. (MPEC S.A.) in Krakow with the simultaneous use of recovered and transformed electrical energy in network facilities. Through the presentation of methods for the recovery of mechanical energy of the heating medium and examples of the use of turbine installations in district heating networks, a potential solution to the problems of the district heating company associated with an excess of disposable pressure in networks and the effects of work carried out to date in Krakow were shown. Conclusions from the test installations carried out to date and a system operating under actual operating conditions in a district heating chamber show the operating methodology and the real benefits of turbine installations for the control of dispatching pressure.

Abstract
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Keywords: microclimate, microorganisms, air pollution

Abstract
In todays world, especially recently in the era of a pandemic, people are increasingly both looking for and using active forms/ modes of life to spend their so-called „free time”. Recently, not only among children and adolescents, but also among adults, it can be noticed that sports activity has become a priority. One of the most frequently chosen sports activities is swimming (both recreational and sports), which can now be carried out in many larger or smaller indoor swimming pools. As a result, more and more people stay in rooms/buildings with a specific microclimate, favoring the emergence/development of various types of microbial infections (in particular, various types of mycoses). To prevent this, in such facilities as indoor swimming pools, it is very important to correctly select mechanical ventilation, which would take into account numerous external and internal parameters of the room. As a consequence, the task of pool ventilation is to maintain a proper microclimate inside the pool hall. At the same time, it should be remembered that unfavorable temperature and humidity conditions may contribute to the discomfort of pool users, but also to the development of various types of microorganisms. What is more, moisture and fungus may have a negative effect on the building structure and contribute to the destruction of building partitions, and the physical and biological corrosion of building elements may threaten the safe use of the facility. Therefore, in order to check the scale of these phenomena, it was decided to analyze the microclimatic and microbiological conditions in the large building of the swimming pool hall (in the building of the Academic Sports and Didactic Center „Zatoka Sportu” in Łódź). Thanks to this, information was obtained about the temperature range, relative humidity, air flow velocity and the number of microorganisms present in the air in the swimming pool hall both in time (with low load on the sports facility and during the greatest load on the facility, i.e. when the greatest sports activity was carried out in it), as well as depending on the location and distance/height from the pool basin. It seems that performing this type of measurements may be helpful, and maybe even necessary, to pay attention to the importance of the correct selection, design and use of mechanical ventilation in this type of facility.