Using Microprocessors to Save Energy

Date01 May 1982
DOIhttps://doi.org/10.1108/eb057259
Published date01 May 1982
Pages28-28
Subject MatterEconomics,Information & knowledge management,Management science & operations
Using Microprocessors to Save Energy
As the cost of fuel rises, so the need to economise on its use
becomes more important. In industry, fuel is used not only
to drive machinery but also for heating industrial premises
(and sometimes for cooling, for example in cold stores and
in hot climates). Considerable saving of fuel used for
heating, or for cooling, can be achieved by means of new
technological innovations, in particular the use of
microprocessors to control temperatures as well as the flow
of hot water or cold or hot air.
At the same time savings can be achieved by conserving
heat. Heat is often wasted by having rooms too hot, either
when occupied or when empty. Heat losses in rooms can
also be reduced by having appropriate insulation in the
building, double glazing for the windows and cavity insula-
tion in the walls. In hot climates the same measures also
keep the heat out of the building and so reduce the fuel us-
ed to keep it
cool.
In fact, energy conservation in buildings
entails close co-operation between the consumers, the
designers of the buildings and of the heating, or cooling,
equipment, and the suppliers of the equipment.
Because heat demands in rooms differ from one another
and also vary at different times of the day, and from day to
day, it is important for each room to have its own ther-
mostat regulating the flow of hot water in the radiators or
the flow of hot, or cold, air in the ducts. Flow of water or
air should be further regulated by a time clock to ac-
comodate the varying temperature requirements
throughout the day and at weekends and holidays. It is
plainly wasteful to heat rooms when they are unoccupied.
A number of authorities, particularly in Europe, are
developing district heating systems. In such systems heat
produced by power stations is distributed by means of hot
water pipes to domestic premises and factories in the
neighbourhood. In the UK a combined heat and power
project (CHP) is being sponsored by the Government. The
concept behind CHP is that power stations operated by the
Central Electricity Generating Board should provide heat
for district heating systems serving towns situated near the
power stations thereby making profitable use of the waste
heat inherent in the electricity generation process.
One of the greatest problems associated with district
heating is the regulation of differential pressures within the
system. District heating schemes comprise numerous small
and medium-size consumers whose premises are equipped
with conventional heating systems which instead of taking
heat from local boilers are connected to the heat distribu-
tion pipelines to the power station. Because of the lengths
of these pipelines the circulating pumps at the power sta-
tion have to generate high differential pressures. For the
efficient functioning of such a system very accurate
temperature and flow measuring instruments are required
as well as valves and pumps that respond precisely to pro-
vide the conditions required.
A company that specialises in the supply of the wide
range of instruments and valves for heating and air condi-
tioning systems is Danfoss Ltd, Perivale Industrial Park,
Horsenden Lane South, Greenford, Middlesex. With their
multinational experience
their headquarters are in Den-
mark they are able to provide advice and consultancy
services on many problems involved in the use of the latest
equipment and techniques in energy saving in this field.
There are many methods by which energy can be saved
in a district heating station. A typical district heating sta-
tion is shown in Figures 1 and 2 below. In this station,
feeding for example an apartment block, the amount of
heat supplied varies from summer to winter. The variation
is approximately in the ratio 1:5. This means that in a
system where differential temperatures between flow and
return have to be maintained near constant, the water flow
must also vary in the ratio 1:5.
Without regulation the supply pump will give high
dif-
ferential pressure in summer and low in winter. This is un-
fortunate because the pump uses as much electricity in
both summer and winter. However, it is possible to reduce
the energy consumption by changing the pump speed con-
currently with heat consumption. Danfoss manufacture a
range of static frequency converters and pressure
transducers suitable for these applications.
28 INDUSTRIAL MANAGEMENT + DATA SYSTEMS

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