STEADY STATE AND DYNAMIC MODELING OF AN INDIRECT DISTRICT HEATING SYSTEM

2010 ◽  
Vol 18 (01) ◽  
pp. 61-75 ◽  
Author(s):  
L. LI ◽  
M. ZAHEERUDDIN ◽  
SUNG-HWAN CHO ◽  
SANG-HOON JUNG
Keyword(s):  
Steady State ◽  
Dynamic Model ◽  
District Heating ◽  
Heating System ◽  
Dynamic Responses ◽  
District Heating System ◽  
Steady State Model ◽  
Heated Floor ◽  
The Impact ◽  
Important System

An indirect district heating system (IDHS) with heated floor area of 851 031 m2 and ten heat exchange stations was modeled in this study. An aggregated steady state model for the system was developed to study the impact of important system parameters. A dynamic model of the IDHS was developed based on energy balance principles. The dynamic model consists of sub-system models such as boiler, pipe network, heat exchanger, terminal heater and zone models. Simulation results of the dynamic responses show that the overall efficiency of the IDHS system is 78.7%, and the two highest heat loss components are the boiler heat losses and the secondary water makeup loss.

Dynamic Analysis of Helical Planetary Gear Train

2013 ◽  
Vol 404 ◽  
pp. 312-317 ◽  
Author(s):  
Xian Zeng Liu ◽  
Jun Zhang
Keyword(s):  
Steady State ◽  
Free Vibration ◽  
Dynamic Model ◽  
Planetary Gear ◽  
Gear Train ◽  
Dynamic Responses ◽  
Design Parameters ◽  
Planetary Gear Train ◽  
State Dynamic ◽  
The Impact

A dynamic model for helical planetary gear train (HPGT) is proposed. Based on the model, the free vibration characteristics, steady-state dynamic responses and effects of design parameters on system dynamics are investigated through numerical simulations. The free vibration of the HGPT is classified into 3 categories. The classified vibration modes are demonstrated as axial translational and torsional mode (AT mode), radial translational and rotational mode (RR mode) and planet mode (P mode) followed by the characteristics of each category. The simulation results agree well with those of previous discrete model when neglecting the component flexibilities, which validates the correctness of the present dynamic model. The steady-state dynamic responses indicate that the dynamic meshing forces fluctuate about the average static values and the time-varying meshing stiffness is one of the major excitations of the system. The parametric sensitivity analysis shows that the impact of the central component bearing stiffness on the dynamic characteristic of the HPGT system is significant.

scholarly journals The use of substations with PCM heat accumulators in district heating system

2018 ◽  
Vol 174 ◽  
pp. 01002 ◽  
Author(s):  
Kinga Nogaj ◽  
Michał Turski ◽  
Robert Sekret
Keyword(s):  
Phase Change Materials ◽  
District Heating ◽  
Heating System ◽  
Economic Benefits ◽  
District Heating System ◽  
Save Energy ◽  
Determination Of Parameters ◽  
Storage Technologies ◽  
The Impact

The main objective of the article is to indicate the directions of development of new generations of supplying buildings with heat, by using phase change materials, referring to the technical possibilities of applying available heat storage technologies. As a detailed objective of the work, the determination of the impact of using a PCM accumulator on the temperature of the heat carrier on the return in the substation of the district heating system was adopted. Range work included determination of parameters of heat distribution network as a function of outdoor air temperature range of -20°C to +12°C. As the analysis object, the heat substation has been selected with the following parameters: supply 80°C and return 60°C. It was found that thanks to the use of PCM accumulators on heat substations, it is possible to save energy by up to approx. 6.7% and achieve economic benefits in the form of a payback period of approx. 13 years. In addition, it was found that the introduction of the PCM accumulator into the heating system allows the return temperature in the heating network to be obtained at a temperature level consistent with the adopted control table for external temperatures of the standard heating season.

scholarly journals Air Quality Planning and the Minimization of Negative Externalities

Resources ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 15 ◽  
Author(s):  
Marco Ravina ◽  
Deborah Panepinto ◽  
Mariachiara Zanetti
Keyword(s):  
Air Quality ◽  
Urban Areas ◽  
District Heating ◽  
Heating System ◽  
Negative Externalities ◽  
District Heating System ◽  
Quality Planning ◽  
Air Quality Planning ◽  
The Impact

The minimization of negative externalities is a key aspect in the development of a circular and sustainable economic model. At the local scale, especially in urban areas, externalities are generated by the adverse impacts of air pollution on human health. Local air quality policies and plans often lack of considerations and instruments for the quantification and evaluation of external health costs. Support for decision-makers is needed, in particular during the implementation stage of air quality plans. Modelling tools based on the impact pathway approach can provide such support. In this paper, the implementation of health impacts and externalities analysis in air quality planning is evaluated. The state of the art in European member states is reported, considering whether and how health effects have been included in the planning schemes. The air quality plan of the Piemonte region in Italy is then considered. A case study is analyzed to evaluate a plan action, i.e., the development of the district heating system in the city of Turin. The DIATI (Dipartimento di Ingegneria dell’Ambiente, del Territorio e delle Infrastrutture) Dispersion and Externalities Model (DIDEM model) is applied to detect the scenario with the highest external cost reduction. This methodology results are extensible and adaptable to other actions and measures, as well as other local policies in Europe. The use of health externalities should be encouraged and integrated into the present methodology supporting air quality planning. Efforts should be addressed to quantify and minimize the overall uncertainty of the process.

scholarly journals Impact of Domestic Hot Water Systems on District Heating Temperatures

Energies ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4694
Author(s):  
Tina Lidberg ◽  
Thomas Olofsson ◽  
Louise Ödlund
Keyword(s):  
Low Temperature ◽  
District Heating ◽  
Heating System ◽  
Hot Water ◽  
Space Heating ◽  
Circulation System ◽  
District Heating System ◽  
Domestic Hot Water ◽  
Temperature Levels ◽  
The Impact

When buildings become more energy effective, the temperature levels of district heating systems need to be lower to decrease the losses from the distribution system and to keep district heating a competitive alternative on the heating market. For this reason, buildings that are refurbished need to be adapted to suit low-temperature district heating. The aim of this paper is to examine whether four different energy refurbishment packages (ERPs) can be used for lowering the temperature need of a multi-family buildings space heating and domestic hot water (DHW) system as well as to analyse the impact of the DHW circulation system on the return temperature. The results show that for all ERPs examined in this study, the space heating supply temperature agreed well with the temperature levels of a low-temperature district heating system. The results show that the temperature need of the DHW system will determine the supply temperature of the district heating system. In addition, the amount of days with heating demand decreases for all ERPs, which further increases the influence of the DHW system on the district heating system. In conclusion, the DHW system needs to be improved to enable the temperature levels of a low-temperature district heating system.

scholarly journals Analysis of the Impact of Decreasing District Heating Supply Temperature on Combined Heat and Power Plant Operation

2014 ◽  
Vol 14 (1) ◽  
pp. 41-46 ◽  
Author(s):  
Alona Bolonina ◽  
Genadijs Bolonins ◽  
Dagnija Blumberga
Keyword(s):  
Power Plant ◽  
District Heating ◽  
Heating System ◽  
Combined Heat And Power ◽  
District Heating System ◽  
Heating Systems ◽  
Plant Operation ◽  
Operation Modes ◽  
Power Plant Operation ◽  
The Impact

Abstract District heating systems are widely used to supply heat to different groups of heat consumers. The district heating system offers great opportunities for combined heat and power production. In this paper decreasing district heating supply temperature is analysed in the context of combined heat and power plant operation. A mathematical model of a CHP plant is developed using both empirical and theoretical equations. The model is used for analysis of modified CHP plant operation modes with reduced district heating supply temperature. Conclusions on the benefits of new operation modes are introduced.

scholarly journals The Impact of Optimal Demand Response Control and Thermal Energy Storage on a District Heating System

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1678 ◽  
Author(s):  
Sonja Salo ◽  
Aira Hast ◽  
Juha Jokisalo ◽  
Risto Kosonen ◽  
Sanna Syri ◽  
...  
Keyword(s):  
Demand Response ◽  
District Heating ◽  
Heating System ◽  
Hot Water ◽  
Production Costs ◽  
Building Stock ◽  
District Heating System ◽  
Response Control ◽  
Water Storage Tank ◽  
The Impact

Demand response has been studied in district heating connected buildings since the rollout of smart, communicating devices has made it cost-effective to control buildings’ energy consumption externally. This research investigates optimal demand response control strategies from the district heating operator perspective. Based on earlier simulations on the building level, different case algorithms were simulated on a typical district heating system. The results show that even in the best case, heat production costs can be decreased by only 0.7%. However, by implementing hot water thermal storage in the system, demand response can become more profitable, resulting in 1.4% cost savings. It is concluded that the hot water storage tank can balance district heating peak loads for longer periods of time, which enhances the ability to use demand response strategies on a larger share of the building stock.

scholarly journals Optimization model for improvement of district heating system by integration of cogeneration

2020 ◽  
pp. 207-207
Author(s):  
Branka Gvozdenac-Urosevic
Keyword(s):  
Carbon Dioxide Emissions ◽  
District Heating ◽  
Goal Function ◽  
Heating System ◽  
Energy System ◽  
Low Carbon ◽  
District Heating System ◽  
Increase Energy Efficiency ◽  
Reduce Carbon Dioxide ◽  
The Impact

Modelling of a complex district heating system by increasing the energy system?s efficiency and by reducing emissions through the implementation of new and low carbon technologies is presented. One of these technologies is cogeneration which is used to increase energy efficiency and to reduce carbon dioxide emissions. Presented model uses linear programming as a basis for mathematical modelling of the energy system. The mathematical calculation is set pragmatically, so it can be efficiently and reliably used to assess the impact of most important parameters on the efficiency of the regional energy system. The model analyses the effects of integration of cogeneration into the existing energy system using a given goal function. The basic criterion is set to be the reduction of environmental impact. The model is successfully tested on the complex district heating system with the power of about 600 MW.

Thermal Storage Systems for District Heating Networks

2010 ◽  
Author(s):  
Vittorio Verda ◽  
Francesco Colella
Keyword(s):  
Electricity Market ◽  
Thermal Load ◽  
Storage Systems ◽  
Fluid Dynamic ◽  
District Heating ◽  
Heating System ◽  
Maximum Load ◽  
Operating Conditions ◽  
District Heating System ◽  
The Impact

District Heating is an efficient way to provide heat to residential, tertiary and industrial users. Heat is often produced by CPH plants, usually designed to provide the base thermal load (40–50% if the maximum load) while the rest is provided by boilers. This choice is made on the basis of economic criteria, in fact the investment cost of a CHP plant is much higher than the cost of boiler, thus its use is convenient when it operates for a large number of hours. The use of storage tanks would permit to increase the annual operating hours of CHP: heat can be produced when the request is low (for instance during the night), stored and then used when the request is high. The use of boilers results partially reduced, thus the thermal load diagram is flattered. Depending on the type of CHP plant this may also affect the electricity generation. All these considerations are crucial in the free electricity market. In this paper, the use of storage systems connected to the district heating systems, is examined. A thermo fluid dynamic model of the tanks is considered in order to calculate the amount of energy actually provided, taking the real operating conditions into account. These considerations are applied to the Turin district heating system, in order to determine the impact of storage systems on the primary energy consumption required to supply heat to the users over the entire heating season.

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