Heating systems, natural sources of energy
Ecological and cheap heating
Recent increase in prices of
energy and fuels has led to the
situation that heating and production of usable hot water (u.h.w.)
costs take now more significant part in the exploitative costs of
buildings. As a result we turn to the solutions which use free energy ources or
to the production of energy with several times higher efficiency when compared
even with a condensing boiler.
All you need to do is to browse through the coursebooks and
guidebooks to find out that our ideas – use of solar energy or
recuperation of heat from boiler room’s exhaust fumes, heat
pumps or energy consolidation - have been known for ages and
they were the topics of lectures in many polytechnics 30 years ago.
In a meantime, new technological opportunities have come into
life what enabled to put theoretical knowledge into practice. Solar collectors
are now produced in many different types (not only the
flat ones), development of cooling compressors’ structures enables to to produce
heat pumps with the efficiency not of 200% but of
400-500%. Wind power stations are not any longer at the
experimental phase and they take a place among other electric
energy producers. Development of boilers’ production has led to the creation of
house heat and power plants.
This technological development must have been verified
economically. And also this aspect of the issue has made it more
friendly to the potential user because the technological
development decreased the price of the final product. As a result,
rather experimental meditations which were supposed to fulfill the
ambitions of rich originals have become very practical solutions in
the activity of technologically advanced companies dealing with installations.
Simulteneously – air pollution caused mainly by big boiler rooms and small
hearths using solid fuels is becoming more and more noticable. Nowadays we heve
at least two-sided pressure on the modernisation of systems producing heat
energy
and aiming at cheap energy production and minimisation of pollution emission
into the atmospheric air. What also can not be belittled is the fact that fuels
appearing on our globe are inevitably ending. Optimistic visions of exploitation
of other planets in the Solar System popular in the times (1960s) of the very
first space explorations because of the development of space flights and because
of their cost – have been delayed. The solution lays in renewable fuels and
sources of energy not using fuels.
In a “small” power industry dealing with heating and producion of usable hot
water inside single-family residential houses or in small hausing estates the
practical possibilities of joining these – mentioned above – problems exists.
The typicalexample of this is a resdential bulding in Freiburg (Switzerland)
which can be energeticly self-sufficient during the whole year – including the
production of electric current. Also in Austria there were built small hausing
estates of single-family buildings which use only about 20% of heat energy used
in our energy-saving house. Unfortunatelly to reach this stage of energy-saving
many problems like: design of installation or architect’s work (locallization,
location according to the quarters of the globe, the shape of the building which
would enable the absorbtion of solar energy, structure of the building enabling
to store the heat from summer an use it in winter etc.) which have to be dealt
with. Articles appearing in the press dealing with the solar energy or heat
pumps can be divided into two groups:
-
very theorethical and in fact they discourage the potential
investor from these kinds of solutions because of the unspecified cost of
realization and lack of clear descriptions of possible realizations;
-
sponsored by big trading companies where the possible profits
of use are visibly exeggerated;
In practice all of these information has to be
averaged. Than it turns out that the profits of exploitation of solar collectors
or heat pumps are relatively high both for investors and the environment itself.
Problems connected with realization are usually easy to solve and the cost of
realization is rather reosnable. So we can say that there are conditions in
which the solutions protecting our environment and at the same time our
pocket can be developed. But there is another obstacle – lack of
professional materials in Polish which would help in the work of our designers.
Modern
boiler rooms have to provide specified amount of heat for several heating
circuits ( which is rather simple and well known procedure both for designers
and installation companies) and produce or receive the heat coming from
different sources and having different temperature level. This second aspect is
commonly omitted in various descriptions used by designers and that is why they
are rather reluctant to deal with it. It has to be said that “traditional”
solutions (different sources of energy connected with one collector) are always
full of unexpected surprises which have to be faced even by the people realizing
the simpliest cascade – heat pump and boiler.
Majority of these problems can be avoided by the use of KOMBI POD. It is a
device which has the functions of: hydraulic swich, heat accumulator, desludger
and capacitif heater of usable hot water.
What is more, it makes it easier to connect many different sources of energy
with one single heat central. Its structure is illustrated in the picture. It is
a steel pod with the capacity of 600-1500 l. with a smaller boiler attached
inside (150-300 l.) which is used as a capacitif heater of usable hot water.
Inside the coating of kombi pod there are several connections installed on the
different levels which enable entering and leaving on the various temperature
levels. Inside the lower part of kombi pod there is a heat exchanger in a form
of pipe coil installed which enables the heat exchange with the heat source
working as an indirect medium like e.g. the system of solar collectors covered
with glycol. When we have
several different heat sources on different temperature levels we connect them
with kombi pod as with a vertical divider. But we have to remember that the heat
source with the lowest temperature (e.g. a solar collector or a heat pump) has
to be connected with the lowest part of the pod and with its higher parts we
connect boiler or boilers. The power supply of heating installation is created
from the connection installed the highest level. The highest temperature level
inside kombi pod (inside its
upper part) heats up the usable hot water which is located inside a smaller
capacitif heater. U.h.w. can be additionally reheated by the boiler itself.
Kombi pod is mainly used in heat centrals which use the solar energy. In this
kind of system there is so called “conflict of interests” because the highest
yield of energy takes place during summer and the highest heat reception takes
place during winter – supposing that we want to use the solar energy not only to
produce the usable hot water but also for heating purposes. Kombi pod has to be
also treated as a heat accumulator. Becauseof the fact that we are inevitably
running out of fuels and that our environment is becoming more and more polluted
the process of modernisation of the methods dealing with the use of solar energy
has been accelerated. The simpliest water solar collector which is a black cask
filled up with water and exposed to the Sun has been greatly modified.
Technological solutions have been changed and the efficiency of systems
absorbing solar energy and changing it into heat is constantly rising. This idea
is extremely popular in countries with the very similar climate like: Ausria,
Germany or
Slovakia. Thi kind of energy is also used in climates far less advantegous than
our – Denmark or Scandinavia. The largest system of solar collectors in Europe
is in Sweden and has the area of 7500m2. It provides the whole town – Nykvar
with hot water. The area of all solar collectors istalled in Austria is now over
1.000.000m2. According to the
statistics from Austria the right selection of solar collectors’ battery in
relation to the number of people using it and the appropriate capacity of hot
water pod, during the entire calendar year 45% of usable hot water can be gained
for free. Obviously the best energetic effect of solar collectors’ operation is
gained during a sunny day in summer but on the other hand nothing is gained
during a night in winter. So the most practical use of solar energy – heating
the usable hot water by the use of solar collectors should be treated as an
alternative heat source. We should always be equipped with a boiler or an
electric heater which could be used during winter and transitional periods. The
typical solar set consisting of 4 solar collectors, a boiler and a differential
thermostat for a single-family house costs about
8500 zl. The best example of profits which can be gained from the use of solar
energy is the largest operating system of solar collectors (with the area of
80m2) which has been providing the 6-storey holiday house in Zakopane with hot
water for 4 years now. A heat
pump is a thermodynamic circuit which transfers the heat from the lower
energetic level to the upper level. It means that it receives the heat from the
substance with lower temperature (lower heat source) and transfers it to the
substance with higher temperature (upper heat source). This process is being
done at the cost of the drive of heat pump. The development of cooling
compressor which are called the “heart” of a heat pump has enabled to reduce the
amount of energy needed by the drive of heat pump and as a result the heat pumps
have gained the efficiency of 400-500%. The effectivness of heat pumps is
measured in the ratio of heat efficiency to driving power. So even the
efficiency of condensing boilers (108%) is not so impressive when compared with
the effects of heat pumps’ operation. But there are also disadvantages connected
with the use of heat pumps. The main source of heat is the heat installation
inside a building but it needs to have more developped area of heat exchange
because the heat pump provides “worse” heat with the temperature of 50oC. So the
best heat receiver is the floor heating or a ventilo-convector.
There are more advantages connected with the use of
ventilo-convectors like air conditioning of buildings during summer. It is
possible to reverse the circuit of the heat pump so that it becomes the
source of “ice water” used in air conditioning. The most common sources of
energy are: watercourses, ponds, lakes, underground pipe coil, system of two
wells, concrete absorbers, waste technological heat, sewage or surrounding air.
This last factor has a serious flaw when the temperature falls down fo -5oC. But
in practice a heat pump is usually supported by a boiler (because of the
reliability of a heat system and the reduction of capital expenditure – the heat
pump provides approx. 60% of the demand for heat and the highest power is
provided by a boiler) and then during almost the entire cold season we can heat
up
using only the heat pump. The number of days with the temperature below -5oC is
rather small.
Heat recuperation from
boiler’s exhaust fumes is a realatively easy process but in practice it can be
used only in gas boilers because the use of other fuels results in the increased
amount of pollution inside exhaust fumes what forces us to clean the recuperator
very often. The efficiency of a boiler can be increased from 92% up to 108% but
only on the condition that vapour is created from condensates and that the heat
from its condensation is received. The perfect installation consisting of all
elemens described above operates in Nowy Sacz, ul. Grottgera 17 - in the
premisies of HEJAN company.
Nowadays the tightness of woodwork unfortunatelly has its drawbacks. Air
circulation inside a building does not take place and it has to be ventilated
more often. Because of the fact that both bathrooms and kitchens have to be
equipped with the blowing out gravitational ventilation we irretrievably lose
the great amount of heat (contained in the air which is being removed). These
two problems can be successfully joined. It is enough to direct the removed air
through the crossed exchanger which will transfer it into blowing in air to the
bedroom or the living room. As a result we will have both: the removal of the
used air and the supply of fresh but already heated up air (due to the heat
received from the removed air). This kind of ventilating mini-centrals are
already produced. The easiest way to realize this idea is to install it inside a
newly-built house or a building which is under repair.
These practical advices can be used in any configuration but in order to gain
the satisfactory economical effect the building can not lose the heat too fast.
Only a wise treatment of newly-designed buildings and a complex
thermo-renowation of buildings being under repair can give expected economical
and exploitative effects.
Recently on the market the new kind of small heat and power plants has appeared.
Apart from the oil or gas boiler they can produce electric current. It is also a
very interesting construction but on the condition that the problem of
sell of electric energy produced by onself will be solved. Administrative
decisions could
naturally accelerate exchanges of heating systems if there was any financial
catalys of this process.
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