Plenary
Lecture
Thermal Energy Storage using PCMs
Professor Mihai Cruceru
Energy Department, Engineering Faculty
"Constantin Brancusi" University of Targu-Jiu
Bd. Eroilor 30, Targu-Jiu, Gorj, Romania, RO 210152
E-mail:
cruceru@utgjiu.ro
Abstract: Buildings are the largest end user of
energy, since 40% of all energy is used in the
residential/tertiary sectors. The energy demand for
cooling or heating applications has been growing
constantly over the past few years. One main reason for
this development is that new buildings are often
constructed by light materials and the lack of thermal
storage capacity leads to fast overheating or subcooling
of the building.
The need of thermal energy storage may often be linked
to the following cases: there is a mismatch between
thermal energy supply and energy demand; when
intermittent energy sources are utilized; for
compensation of the solar fluctuation in solar heating
systems.
The use of thermal storage walls that serve both as
solar collector and thermal storage is well known. The
wall is usually composed of masonry or containers filled
with water to provide sensible heat storage resulting
from the specific heat capacity of a material as it
increases in temperature.
Sensible heat energy storage has the advantage of being
relatively cheap but the energy density is low and there
is a gliding discharging temperature. To overcome these
disadvantages phase change materials (PCMs) can be used
for thermal energy storage.
PCMs are materials capable of increasing thermal inertia
of buildings without increasing the thickness of walls,
for instance. In comparison with other thermal storage
materials, such as concrete or water, PCMs have a higher
energy storage density. In that way, one can achieve the
same goal with less material. On the other hand, PCMs
also allow the storage and the release of thermal energy
at an almost constant temperature.
A research group from "Constantin Brancusi" University
from Targu-Jiu patented a new type of composite wall
system incorporating PCMs and evaluated its potential
for air conditioning/heating energy savings in
continental temperate climate.
The novelty of the wall system consists of the fact that
two PCM wallboards, impregnated with different PCMs are
used. The structure of the new wall system is that of a
three-layer sandwich-type insulating panel with outer
layers consisting of PCM wallboards and middle layer
conventional thermal insulation.
The PCM wallboard layers have different functions: the
external layer has a higher value of the PCM melting
point and it is active during hot season and the
internal layer with a PCM melting point near set point
temperature for heating is active during cold season. A
year-round simulation of a room built using the new wall
system was carried out and the effect of PCM presence
into the structure of the wall system was assessed. It
was found that the new wall system contributes to annual
energy savings and reduces the peak value of the
cooling/heating loads.
Brief Biography of the Speaker:
Mihai CRUCERU, born on 02.07.1967 in Targu-Jiu, Romania,
graduated from Installations for Buildings Faculty,
Technical University of Civil Engineering Bucharest
(1991), where he obtained also his PhD (1998). He worked
for one year as HVAC engineer and he joined in 1992 the
Energy Department from "Constantin Brancusi" University
Targu-Jiu where he is now professor of Heat Transfer and
Energy Management. He was Dean, Head of Department for
Education Quality, and now he is Vice-Rector for
Education. His research is focused on Heat and mass
transfer, Thermal equipment design and Energy
efficiency. He is Energy auditor and Thermal equipment
and fluid systems expert. He was involved, as director
or researcher, in 18 national and international research
projects. He published 11 books and more than 110
articles in relevant journals and conference
proceedings.
|