Dynamic equation-based thermo-hydraulic pipe model for district heating and cooling systems

District heating and cooling systems have been undergoing continuous development and have now reached the fifth-generation. In this innovative technology, connected buildings share local excess energy that otherwise would be wasted, which consequently reduces primary energy demands and carbon emissions. To date, the issue of implementing fifth-generation district systems on existing buildings has received scant attention, and our research addresses this challenging gap by proposing a novel method for designing these systems. We first explain the possible thermal interactions between connected buildings, and then present an analytical solution for the network energy balance, pipe design, and the prediction of fluid temperature under a fixed temperature difference control strategy. The analytical solution was validated against numerical simulations performed on 11 existing buildings located in Lund, Sweden using Modelica models. A diversity index metric between heating and cooling demands was also included in these models to assess the efficiency of the district system in the building cluster. The results from the analytical and numerical solutions were in complete agreement since Modelica is an equation-based modelling language. The developed models pave the way towards future investigations of different temperature control strategies and new business models that arise from the shift to the fifth-generation.

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District heating and cooling systems for communities through power plant retrofit and distribution networks. Phase 1: identificaion and assessment. Final report

10.2172/5588629 ◽

1979 ◽

Author(s):

Keyword(s):

Power Plant ◽

Phase 1 ◽

District Heating ◽

Distribution Networks ◽

Final Report ◽

Cooling Systems ◽

Heating And Cooling

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Power Piping

10.1115/b31.1-2004 ◽

2010 ◽

Keyword(s):

High Temperature ◽

District Heating ◽

Cooling Systems ◽

Heating Systems ◽

Geothermal Heating ◽

Heating And Cooling ◽

Piping Systems ◽

Minimum Requirements ◽

Pressure Water ◽

Temperature Water

ASME B31.1 prescribes minimum requirements for the design, materials, fabrication, erection, test, inspection, operation, and maintenance of piping systems typically found in electric power generating stations, industrial and institutional plants, geothermal heating systems, and central and district heating and cooling systems.It also covers boiler-external piping for power boilers and high-temperature, high pressure water boilers in which steam or vapor is generated at a pressure of more than 15 psig; and high temperature water is generated at pressures exceeding 160 psig and/or temperatures exceeding 250 degrees F.

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Integration Of Pipe Models In Delphin And NANDRAD

E3S Web of Conferences ◽

10.1051/e3sconf/202017212012 ◽

2020 ◽

Vol 172 ◽

pp. 12012

Author(s):

Dirk Weiß ◽

Katja Tribulowski ◽

Stephan Hirth ◽

Heiko Fechner

Keyword(s):

Heat Input ◽

Building Simulation ◽

Simulation Program ◽

Heat Radiation ◽

Building Structures ◽

Cooling Systems ◽

Heating And Cooling ◽

Pipe Model ◽

Coupled Heat And Moisture ◽

Energy Gains

The component simulation program DELPHIN, which is usually used for component simulation including coupled heat and moisture transport, has also implemented a pipe model that is currently not documented. This model can be used for various purposes, including the modelling of heat input/output by surface heating/cooling systems in building structures. Furthermore, it allows an estimation of energy gains and storage potentials by ground collectors by considering the ground including the collector pipe, etc. The same pipe model is implemented isotropically in NANDRAD in order to model and to consider underfloor heating systems in the thermal building simulation. The implementation of this pipe model for DELPHIN (component simulation program) and NANDRAD (building simulation program) is described, investigated and documented in this paper for underfloor heating and cooling systems. Especially the heat transfer between pipe wall and fluid is discussed in more detail. Therefore, the parameterization and the flaw between the anisotropic tube model (two-dimensional heat radiation inside the component) in Delphin and the isotropic model (heat input to a component layer) in NANDRAD are being examined.

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