Analysis of the Systems for Thermal Energy Supply at the Living Lab

226 Pages·2016·18.08 MB·English

by  Stian Johansen Lillevåg

Analysis of the Systems for Thermal
Energy Supply at the Living Lab
Analyse av systemer for termisk
energiforsyning ved Living Lab
Stian Johansen Lillevåg
Master of Energy and Environmental Engineering
Submission date: June 2016
Supervisor: Jørn Stene, EPT
Co-supervisor: Hans Martin Mathisen, EPT
Norwegian University of Science and Technology
Department of Energy and Process Engineering
Preface
This Master’s Thesis was written at the Norwegian Univeristy of Science and Technol-
ogy during the spring semester of 2016. It represents my concluding works at the five
year study program Energy and Environmental Engineering, and comprises 30 ECTS
credits.
I would like to thank my academic supervisor, Jørn Stene, for providing me with an in-
teresting topic, and for insightful guidance and feedback along the way. I would also
like to thank my research advisor, Hans Martin Mathisen, for helpful support and ad-
vices. A special thanks goes to Torgeir Viking Skiple, for valuable feedback and support
during my work on this report.
At last, I would like to express my gratitude towards the employees at the Department
of Energy and Process Engineering, who have made contributed in making field mea-
surements and data acquisition possible. In particular, Reidar Tellebon and Inge Hå-
vard Rekstad, for help with external measuring equipment, and Stein Kristian Skånøy,
for help with LabVIEW controls.
Trondheim, 22.06.2016
Stian Johansen Lillevåg
i
ii
Abstract
The main purpose of this Master’s Thesis has been to analyze the systems for thermal
energy supply at the ZEB Living Lab, at NTNU, Trondheim. The 102 m2 single-family
house is designed and built in accordance with the Norwegian passive house standard,
as a Zero Emission Building. Efficient utilization of on-site renewable heat sources,
such as ground and solar heat, are thus essential means to reach this ambitious goal.
The thermal energy supply system comprises a 3.2 kW ground-source heat pump unit,
4.2 m2 of south façade-mounted solar panels, a 400 l integrated water tank, including
two 3.0 kW back-up heaters, and an hydronic heat distribution system. A combination
of theoretical and experimental approaches have been applied in the analyze. Thermal
energy and power demands from SIMIEN simulations, resulted in a heat pump power
coverage factor of 54 %, at 0/35 °C. Energy coverage factors were 70 % and 85 %, with
and without DHW heat supply. Corresponding SPF values were 2.56 and 3.52. Polysun
simulations of the solar thermal system gave an annual solar fraction of 0.37, and a
value of 0.6 for DHW heating during the summertime.
Results and observations from measurements have revealed a potential for improve-
ment of system operating strategies, performance, design and dimensioning. The heat
pump system is designed for alternate operation between space and DHW heating,
but is currently incapable of the latter. Direct-acting electricity is thus an important
heat producer in the system. The solar thermal system is designed for combined space
and DHW heating, but is operated too intermittently to provide significant heat input.
Low-temperature solar heating is furthermore prioritized by the integrated water tank,
which restricts the potential for high-temperature DHW heating during the summer.
Field measurements have shown a significant electric power consumption for opera-
tion of pumps. The electric power input to the ground circuit pump, for instance, cor-
responded to 15 % of the power input to the heat pump compressor. This contributed
to a 13.5 % reduction in the heat pump system COP. Replacement of the brine solution
is one of the suggested measures to redeem this deficiency.
In order to obtain the energy savings necessary to reach the ZEB goal, it is essential that
the electric energy input to pumps and electric heaters is minimized. Meanwhile, the
operating time for the heat pump unit and solar thermal system has to be extended.
It is also essential that the measuring equipment is fully functional, so that the system
energy performance can be documented.
iii
iv