Optimization of heat loads on the HVАС systems of a residential building in Brody, Lviv region
Students Name: Myso Andrii Vasylovych
Qualification Level: magister
Speciality: Heat and Gas Supply and Ventilation
Institute: Institute of Civil Engineering and Building Systems
Mode of Study: part
Academic Year: 2020-2021 н.р.
Language of Defence: ukrainian
Abstract: Relevance of the topic: excessive consumption of thermal energy in the housing stock of Ukraine. Purpose: Analysis of ways of heat loss by a residential building, determining the directions of their reduction. Determining the possibility of accumulation of thermal energy in the structure of the building and the use of electric heating systems during the failure of electricity consumption. Scientific novelty of the work: optimization of heat loads on the HGV systems of a residential building by optimizing air exchange and the use of two electric heating systems to determine their optimal ratio. In this work, the ways of heat loss by a residential building were analyzed and the directions of their reduction were determined, namely the analysis and calculations of different variants of the multiplicity of air exchange in the premises were carried out: - air exchange by the number of Petenkofer according to the normative minimum values of areas and work performed; - air exchange by the number of Petenkofer according to the actual area. - air exchange according to sanitary and hygienic norms of Ukraine at normative minimum areas of premises; - air exchange according to sanitary and hygienic norms of Ukraine and actual areas of premises. Air exchange optimization was carried out, where it was found that energy-efficient technical solutions for ventilation should be based on a new concept, the meaning of which is determined by the following provisions: - it is not necessary to demand from natural ventilation a full-fledged air exchange round the clock. Means of natural ventilation must provide a minimum air exchange (passive air exchange), sufficient for the ventilation mode of premises in which there is temporarily no one; - in the presence of people in the room, active air exchange must be provided by means of mechanical ventilation, which is switched on automatically. Bathrooms and kitchens should be actively ventilated when they are used; - in mechanical ventilation there is a mandatory use of thermal energy recuperators. After a comparative calculation of air exchange on the example of this house, it is established that the optimal air exchange of individual apartments is to provide a single air exchange in the bedroom and living room. The volume of supply air to the kitchen should also partially cover the lack of air needed for the bathroom and toilet. The use of a heat exchange device such as Prana is impractical at a given heat balance. Heat savings are possible by reducing the amount of exhaust air (kitchen, bathroom, bath) by 25% by installing exhaust fans in the room (automatic operation) It is possible to save on heat losses caused by ventilation in case the total area of living rooms is more than 55 m2. If the area increases by more than 55 m2, it is possible to reduce the air exchange rate to 0.6 times, as well as to use a heat exchange device such as Prana. The total heat loss of the house by months before and after the optimization of heat loads was determined, as well as the calculated costs of heating in these cases, respectively 133724 UAH and 88179 UAH / year Emphasis is placed on the schemes of application of the latest equipment to ensure the microclimate of the building, which does not provide for the use of gas, and its connection to the building in general. Because it is these schemes of application of the latest equipment that can create the foundation for energy efficiency of buildings in the future. The graphs of electricity consumption in the heating period in Lviv region for the last 5 years are presented, which proves that the economically justified share of total capacity of electric heating storage systems is approximately 30% of daily electricity consumption in Lviv region in winter, equal to night failure of daily electricity consumption schedule. It was decided to use a heat-accumulating electric cable heating system (HAECHS), after which the calculated amplitude of air fluctuations in the room was calculated. The choice of thermal loads on the main and peak heating system is made From the above-mentioned heat-accumulating electric cable heating system it is established that for HAECHS the maximum load reaches up to 70% of the calculated one based on the maximum heat flow of the floor surface. The amplitudes of oscillations of the indoor air of all heating rooms are obtained. It is determined that HAECHS provides comfortable conditions: - based on the maximum oscillation amplitude of 1.5 ?C) on average for residential premises at ts = -6? C; - in the least heat-resistant living space (№220) the amplitude of oscillations at tз = - 6?С will be equal to 1,93?С, which <2.5 according to the norms - based on the maximum amplitude of oscillations of 2.5 ?C on average for the kitchen at ts = -4.9 ?C - in the least heat-resistant kitchen room (№208) the amplitude of oscillations at tз = -6? С will be equal to 4,2?С, (the kitchen does not belong to the class of rooms with constant stay of people). According to the calculation, graphs of fluctuations in the internal temperature of rooms for different purposes (kitchen, living room) at maximum and average values, the amplitude of fluctuations, depending on the external air temperature during the heating period. To compensate for the remaining (30%) heat loss, two options for installing a peak heating system were considered: - water heating system (steel, stamped radiators with lower connection and with built-in HEIMER temperature regulators are used as heaters; - electric heating system (electric ML wall convectors are used as heaters) Taking into account the average monthly outdoor air temperatures, as well as analyzing the outdoor air temperatures for the heating period 2016-2019. It is obvious that the peak heating system will work only on certain days during the heating period, so in the future two peak systems (radiator and electric) are calculated and on the basis of economic comparison the final choice of the system is made. It is established that optimization of air exchange allows to save 16% of thermal energy The use of two electric heating systems (basic EXO TA and peak, namely electric heaters) with a heat flux ratio of 70 to 30%, while providing comfortable conditions allows you to save up to 14% of thermal energy, as well as significant funds to heat consumers due to electricity tariffs in hours of night minimum loads of the power system in the Lviv region. The total possible savings of thermal energy is 30% List of used literature sources 1. DBN B.2.2-15: 2019 Dwelling houses. Substantive provisions. 2. DBN B.2.6-31: 2016 * Thermal insulation of buildings. The official publication is the Ministry of Construction, Architecture and Housing and Communal Services. Kyiv-2006 3. DBN B.2.5-67: 2013 “Heating, ventilation and air conditioning” - K .: Ministry of Construction of Ukraine, 2013 4. Bogoslovsky VN, Scanavy AN Heating.- M .: Stroyizdat, 1991. 5. Designer’s Handbook. Internal sanitary devices. Part 1. Heating_ M .: Stroyizdat, 1990. 6. Designer’s Handbook. Modern internal equipment of hot and cold water supply, central heating and underground heating. KAN-therm systems Warsaw, 1999. 7. Catalog of HERZ, 1997-1998. Hertz Armaturene GmbH. 8. Gavrishkevich VF Manual for the design of water heating to DBN B.2.5-56: 2014 "Heating, ventilation and air conditioning" ._ K .: Ukrainian Research and Design Institute for Civil Engineering, 2001.