A.A. Nikitin, V.A. Nikitina, A.B. Sulin, T.V. Ryabova
Buildings consume huge amounts of energy, especially the heating systems. Usually the heated exhaust air from the premises is simply thrown out into the external environment, onto the street. In this work, such air is considered as a secondary energy resource formed from the internal loads of the room. The study of the dynamics of changes in the power of internal loads and their influence on the operation of the heat exchanger installed on the exhaust was carried out using the Energy Plus software package. The simulation result showed the utilization capacity of the heat of the exhaust air as an energy resource. The recovered heat from the exhaust air can be used to partially reduce the energy consumption by the heating system.
The purpose of this work is to study the connection between the internal loads of the building and the capacity of the installed heat exchanger at the exhaust.
An example of heat recovery is Stockholm Central Station, where about 250,000 people pass through every day, and the energy generated from them is used to heat a 17-story office building. The created system converts excess body heat into hot water through heat exchangers in the ventilation system. And then the heated water is supplied to the heating system of the office building. Presented heat recovery system cannot fully heat the building, but it helps to reduce the energy consumption of the building by 10%.
The Energy Plus software package was used to analyze the heat recovery process. For the calculation, 2 rooms were chosen, the Daikin laboratory and the classroom 4212, which are located on the 2nd floor of one of the buildings of ITMO University. Program uses the heat-transfer properties of the building envelope, solar radiation, indoor air conditions, as well as infiltration through window area. To analyze the behavior of thermal energy, the heat exchanger was built into the model, which cools the exhaust air to 5°C. Heat capacity that can be extract from the exhaust ventilation system depends on the number of people, equipment, lighting, solar radiation and infiltration. The values of these parameters are changing dynamically. To analyze the heat rate, it is necessary to use energy modeling methods using the Energy Plus software package. Using the constructed mathematical model, the maximum power of the heat recovery system in the classroom was calculated equal to 4 840 W, and 4 630 W in the laboratory during the day. And for a whole month, we can get 80,546 kW of heat.
The interaction between the power of the heat exchanger and the dynamically changing loads inside the building spaces were analyzed. The obtained results showed the potential of heat recovery, which is often not used in the development and design of engineering systems of buildings and structures. It was found that at a relative humidity in the range from 10 to 40%, from 3,500 W to 5,000 W of heat is generated. Such heat generation refers to the winter period of the year, as well as the inter-season. And in this exact time of the year that heat recovery is needed, which will be aimed at reducing energy consumption by the building heating system.
|Publication||IOP Conference Series: Earth and Environmental Science|
|Affiliation of speaker||ITMO University|