Exergy analyses of heat supply systems for a building cluster with CARNOT

Year 2017, Volume: 20 Issue: 4, 191 - 198, 29.11.2017

Paul Michael Falk , Frank Dammel Peter Stephan

https://doi.org/10.5541/eoguijt.299926

Cited By: 2

Abstract

In this paper, a
model to simulate community heating systems is presented and energy and exergy
analyses are conducted for a district heating system with three different heat
generation alternatives. The alternatives are a gas boiler system, a system assisted
by solar thermal collectors with a seasonal thermal energy storage and a gas
boiler as backup, and a system with geothermal borehole heat exchangers
combined with a heat pump. The heat supply of a building cluster of 11
buildings is dynamically modeled using the MATLAB/Simulink based toolbox
CARNOT. The aim is to match the low exergy heating demand with a low exergy
heat source. To cover an energy demand of 263.7 MWh/a, the geothermal
system needs 174.0 MWh/a of exergy, the solar thermal system 269.2 MWh/a
of exergy and the gas boiler system 324.9 MWh/a. A parameter study of the
solar thermal system shows better results for lower supply temperatures and a
lower heat loss coefficient k, but
the results depend strongly on the chosen storage size. It was found that the
use of fossil fuel could be reduced by 43.8 % for the geothermal system
and by 17.6 % for the solar thermal system compared to the gas boiler
system. 

Keywords

Exergy analysis, solar thermal collector, seasonal thermal energy storage, building cluster, heat pump, geothermal borehole heat exchanger, CARNOT, dynamic model, LowEx, low exergy

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