Using Genetic Algorithms and the Exergonomic Approach to Optimize District Heating Networks

This paper discusses the application of exergy analysis to a district heating network (DHN) currently in operation in Brescia (Italy). The purpose is to compare the existing system design with that resulting from an exergonomic analysis. To this aim a general mathematical model is formulated to account for irreversibilities due to the temperature and pressure losses as well as for the assessment of exergy costs for each stream. The objective function is stated as the sum of capital, operational, and maintenance costs of the whole DHN. Such a function is minimized by using two different approaches: an iterative procedure and a genetic algorithm; the latter proves to be particularly suited for this type of problem. Both methods lead to comparable outcomes in terms of minimum cost and plant arrangement. Finally, the optimum configuration is compared with the existing one and shows that the actual network is far from an optimum design both from a thermodynamic and an economic standpoint. Such a procedure could be used profitably in the design of any future DHN.

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A Dynamic Optimization Tool to Size and Operate Solar Thermal District Heating Networks Production Plants

Energies ◽

10.3390/en14238003 ◽

2021 ◽

Vol 14 (23) ◽

pp. 8003

Author(s):

Régis Delubac ◽

Sylvain Serra ◽

Sabine Sochard ◽

Jean-Michel Reneaume

Keyword(s):

Optimization Problem ◽

Total Duration ◽

District Heating ◽

Nonlinear Problems ◽

Solar Thermal ◽

Computational Time ◽

Production Plant ◽

Solar Thermal Energy ◽

Optimum Configuration ◽

Heating Networks

The aim of the ISORC/OPTIMISER project is to increase and improve the use of solar thermal energy in district heating networks. One of the main tasks of the project is to develop an optimization tool for the sizing and operation of a solar district heating network. This is the first optimization tool using an open-source interface (Julia, JuMP) and solver (Ipopt) to solve nonlinear problems. This paper presents the multi-period optimization problem which is implemented to consider the dynamic variations in a year, represented by four typical days, with an hourly resolution. The optimum is calculated for a total duration of 20 years. First, this paper presents the modeling of the different components of a solar district heating network production plant: district network demand, storage and three sources, i.e., a fossil (gas) and two renewable (solar and biomass) sources. In order to avoid prohibitive computational time, the modeling of sources and storage has to be fairly simple. The multi-period optimization problem was formulated. The chosen objective function is economic: The provided economic model is accurate and use nonlinear equations. Finally the formulated problem is a nonlinear Programming problem. Optimization of the studied case exhibits consistent operating profiles and design. A comparison is made of different types of storage connection at the production site, highlighting the relevance of placing the storage at the solar field outlet. The optimum configuration supplies 49% of demand using solar energy, achieving a renewable rate of 69% in combination with the biomass boiler.

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The Impact of Modified EU ETS Allocation Principles on the Economics of CHP-Based District Heating Networks

SSRN Electronic Journal ◽

10.2139/ssrn.1783560 ◽

2011 ◽

Cited By ~ 74

Author(s):

Günther Westner ◽

Reinhard Madlener

Keyword(s):

District Heating ◽

Eu Ets ◽

The Impact ◽

Heating Networks

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RELaTED Project: New Developments on Ultra-Low Temperature District Heating Networks

Proceedings ◽

10.3390/proceedings2020065008 ◽

2020 ◽

Vol 65 (1) ◽

pp. 25

Author(s):

Antonio Garrido Marijuan ◽

Roberto Garay ◽

Mikel Lumbreras ◽

Víctor Sánchez ◽

Olga Macias ◽

...

Keyword(s):

Low Temperature ◽

High Performance ◽

Waste Heat ◽

District Heating ◽

Hot Water ◽

Thermal Systems ◽

Heating Source ◽

Wide Range ◽

Thermal Sources ◽

Heating Networks

District heating networks deliver around 13% of the heating energy in the EU, being considered as a key element of the progressive decarbonization of Europe. The H2020 REnewable Low TEmperature District project (RELaTED) seeks to contribute to the energy decarbonization of these infrastructures through the development and demonstration of the following concepts: reduction in network temperature down to 50 °C, integration of renewable energies and waste heat sources with a novel substation concept, and improvement on building-integrated solar thermal systems. The coupling of renewable thermal sources with ultra-low temperature district heating (DH) allows for a bidirectional energy flow, using the DH as both thermal storage in periods of production surplus and a back-up heating source during consumption peaks. The ultra-low temperature enables the integration of a wide range of energy sources such as waste heat from industry. Furthermore, RELaTED also develops concepts concerning district heating-connected reversible heat pump systems that allow to reach adequate thermal levels for domestic hot water as well as the use of the network for district cooling with high performance. These developments will be demonstrated in four locations: Estonia, Serbia, Denmark, and Spain.

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State estimation models of district heating networks for integrated energy system considering incomplete measurements

Applied Energy ◽

10.1016/j.apenergy.2020.116105 ◽

2021 ◽

Vol 282 ◽

pp. 116105

Author(s):

Suhan Zhang ◽

Wei Gu ◽

Haifeng Qiu ◽

Shuai Yao ◽

Guangsheng Pan ◽

...

Keyword(s):

State Estimation ◽

District Heating ◽

Energy System ◽

Integrated Energy System ◽

Heating Networks ◽

Estimation Models

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Reliability segment design in single-source district heating networks based on valve network models

Sustainable Cities and Society ◽

10.1016/j.scs.2020.102463 ◽

2020 ◽

Vol 63 ◽

pp. 102463

Author(s):

Ding Mao ◽

Peng Wang ◽

Wei Wang ◽

Long Ni

Keyword(s):

District Heating ◽

Network Models ◽

Single Source ◽

Heating Networks

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Conventional and Advanced Exergoeconomic Analysis of a Compound Ejector-Heat Pump for Simultaneous Cooling and Heating

Energies ◽

10.3390/en14123511 ◽

2021 ◽

Vol 14 (12) ◽

pp. 3511

Author(s):

Ali Khalid Shaker Al-Sayyab ◽

Joaquín Navarro-Esbrí ◽

Victor Manuel Soto-Francés ◽

Adrián Mota-Babiloni

Keyword(s):

Heat Pump ◽

Exergy Analysis ◽

Waste Heat ◽

District Heating ◽

Cost Comparison ◽

Exergy Destruction ◽

Pump System ◽

Heat Pump System ◽

Destruction Rate ◽

Exergoeconomic Analysis

This work focused on a compound PV/T waste heat driven ejector-heat pump system for simultaneous data centre cooling and waste heat recovery for district heating. The system uses PV/T waste heat as the generator’s heat source, acting with the vapour generated in an evaporative condenser as the ejector drive force. Conventional and advanced exergy and advanced exergoeconomic analyses are used to determine the cause and avoidable degree of the components’ exergy destruction rate and cost rates. Regarding the conventional exergy analysis for the whole system, the compressor represents the largest exergy destruction source of 26%. On the other hand, the generator shows the lowest sources (2%). The advanced exergy analysis indicates that 59.4% of the whole system thermodynamical inefficiencies can be avoided by further design optimisation. The compressor has the highest contribution to the destruction in the avoidable exergy destruction rate (21%), followed by the ejector (18%) and condenser (8%). Moreover, the advanced exergoeconomic results prove that 51% of the system costs are unavoidable. In system components cost comparison, the highest cost comes from the condenser, 30%. In the same context, the ejector has the lowest exergoeconomic factor, and it should be getting more attention to reduce the irreversibility by design improving. On the contrary, the evaporator has the highest exergoeconomic factor (94%).

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Method for Redesign of District Heating Networks within Transition from the 2nd to the 3rd Generation

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.657.689 ◽

2014 ◽

Vol 657 ◽

pp. 689-693

Author(s):

Răzvan Corneliu Lefter ◽

Daniela Popescu ◽

Alexandrina Untăroiu

Keyword(s):

District Heating ◽

Design Stage ◽

Heating Systems ◽

Load Duration ◽

Load Duration Curve ◽

District Heating Systems ◽

Consumption Rates ◽

Heat Loads ◽

Heating Networks

Important investmentsare made lately in the area of district heating, as a technology capable ofhelping countries to reach sustainability goals. In Romania, European fundswere spent for transition from the 2nd to the 3rdgeneration of district heating systems. The lack of appropriate monitoringsystems in old district heating systems makes optimisation nowadays very difficult,especially because nominal values used in the first design stage areoverestimated. Realistic nominal heat loads are necessary to make goodestimations of hydraulic parameters to be used for redesign. This studyproposes a method that uses the heat load duration curve theory to identify theappropriate nominal heat loads to be used for redesign. Comparison betweenresults obtained by applying the nominal heat loads of each consumer, as theywere established in the first design stage, and the ones identified by theproposed method are analyzed in a case study. The results show that errors arein the +/- 3% band, between the metered heat consumption rates and the proposedrates. The new method can be used for the sizing of pumps and district heatingnetworks after retrofit, in order to get better adjustments of the circulationpumps and increase of the energy efficiency.

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