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2 Description
This innovative storage system was developed for the market
segment of existing multi-family buildings. It was developed
by CONSOLAR and the Research and Test Centre for Solar
Energy Systems (TZS) of the Institute of Thermodynamics and
Thermal Engineering (ITW) at the University of Stuttgart. It
was funded by the Federal Ministry for Economic Affairs
and Energy (Germany). The modular buffer store allows for
storage capacities of up to 11 m³ in particular in existing
multi-family buildings due to its modularity.
The buffer store is designed as a pressurised vessel, so that
it can be connected by the installer in the usual manner. This
also enables an efficient operation without heat exchang-
er between store, heating circuit and heat generator. The
seal-to-seal assembly and the integrated piping ensure good
space utilization and minimize heat losses. There is a Euro-
pean patent application for the storage system.
2�1 Special benefits
Modular system fits through any standard door
The individual modules fit through 70 cm doors and can
be brought in existing buildings with narrow entrances and
assembled on-site.
Pressure tested
The modular store is designed to work up to 3 bar operating
pressure, so that the heat generator and heating circuits can
be directly connected.
Flexible integration
The 5 connectors on each side of the store allow for a
flexible use as a heater buffer or – in conjunction with a
fresh water station – as a combined thermal store in a wide
variety of applications.
Layered loading and unloading
Running through the entire length of the store, loading and
unloading loading tubes allow a clean layered loading and
unloading through the outlet slots with flow reversal.
Integrated mixing-free hydraulic diverter
The water from the boiler can flow directly into the heating
circuit without any losses due to mixing.This behavior can
be achieved if the heat generator is connected on side of the
store and the heating circuit on the other side of the same
tube. Then only the water the heating circuit is not using
flows into the buffer through the slots in the tube. This behav-
iour is especially important for heat pumps, where any drop
in temperature should be avoided.
2�2 Insulation system
Minimized heat loss is achieved by an innovative insulation
system optimised in detail
LEEPS insulation
The LEEPS insulation greatly reduces heat loss. Radiant heat
losses are reduced by the silver foil lining on the vessel and the
fact that the insulation does not contact the vessel. Also the air
chambers within the insulation shell reduce heat loss trough
static air cushions and by reflecting the radiant heat. The insert-
ed LEEPS foam has a very good insulation value.
Insulation
Container Wall
On the container
adjacent insulation
LEEPS insulation with
Radiation brake
Insulation
Plastic feet
Plastic feet reduce the conduction of heat to the floor.
High
Heat losses
Low
Heat losses
Conventional
Steel floor stand
Floor
Plastic feet
Floor
Connections with heat brakes
The thick soft insulation of the front/back enables the (on-site)
mounting of anti-thermosyphon connections within the insula-
tion. As a result, the otherwise high conduction heat losses are
greatly reduced, without increasing the insulation.
Optional: With or without vacuum insulation
The LEEPS insulation shell allows the incorporation of vacuum
insulation panels (VIP). If desired, they are inserted into the air
chambers within the insulation shell. They significantly reduce
the heat losses further.
The following graphic shows that the heat loss of the VARICAL
system is significantly lower when compared to a cascade of
common stores that fit through a standard door and have an
ErP efficiency class of A or B.
0
200
400
600
800
1000
1200
0
2000
4000
6000
8000
10000
Heat loss in W
Store volume in liter
VARICAL with VIP
A[W]
VARICAL without VIP
B[W]
Heat loss of VARICAL in comparison with a cascade consisting of 900 l stores
with the same total volume� Calculated on the basis of readings for 3 modules,
see section 4� Graphics: ITW
T D M A - VA R I C A L :
Description