Note: Descriptions are shown in the official language in which they were submitted.
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PIPE APPARATUS IN HEAT ACCUMULATOR
BACKGROUND OF THE INV~ lON
Until now there are problems in providing long lasting
heat and efficient accumulators coupled with existing heat
exchange systems. Known heat accumulators tend to crack and are
destroyed within a short period after completion.
The increasing cost of energy has let to studies of
various energy conservation schemes concerned with using cheaper
off-peak electrical energy and putting it to practical use.
Various methods to convert cheaper off-peak electrical energy into
heat and store it for use in daytime applications in the subject
matter of several PCT applications, of which application No.
0183327 discloses a contact heat accumulator arrangement and
application No. 0183328 discloses a heat accumulator arranged in a
heat exchanger configuration with a cooling/heating machine.
The prior art EPO patent application No. 83903597.9
discloses a more effective heat accumulator in combination with a
heat exchanger. This combination uses for instance a water tank
as storage vessel. In order to provide an energy storage capacity
at a reasonable level, a large space and expensive constructions
are required. Other known constructions are based on complex
arrangements which are expensive and constitute doubtful solutions
to the problem of using cheap electrical energy available in off-
peak periods such as at night. In the prior art, the heat
accumulator is connected in series to a heating system and large
volume heat transfer pipes of the chamber type are arranged in a
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heat accumulator block of a high heat capacity.
These pipes are dimensioned so that vapour is formed in
the chambers when there is no heat transfer from the block. When
restarting the heat transfer, the vapour is pressed out
successively from each chamber. Such operation involves control
problems.
SUMMARY OF THE lNV~ ION
In order to reduce the risk of uncontrolled vapour
distribution there is suggested a condenser in the outlet from the
accumulator and/or separate vapour outfeed from individual
chambers. Another system requires an auxiliary condenser
arrangement comprising a water system including an expansion
vessel, a pump and a control means for the pump sensing the
temperature in the system heated by the heat accumulator.
This invention is also related to the pipes to press out
steam, the vaporized state of water, as a heat transfer material
in such heat accumulators. Other materials besides water can be
used as the heat transfer material. In the following brief
explanation of this invention, water is used as an example of a
heat transfer material. The heat accumulator comprises a body of
a material having a high heat capacity and a high melting point,
for instance cast iron, ceramics, etc., and the body is designed
to be heated by electrical energy to a temperature considerably
higher than the normal maximum temperature of a heat exchanger in
thermal contact with the accumulator body from 10 p.m. to 6 a.m.
The heat accumulator body heated by electrical energy is covered
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with an insulating material (adiabator) in order to reduce thermal
heat losses.
In the daytime most electric energy is used in factory
and business areas from 9 a.m. to 6 p.m. and the heat stored in
the heat accumulator may be used to make hot water for domestic
home use. The heat accumulator can be heated by electrical energy
during the lunch hour from for example 12 a.m. to 1 p.m. as with
the cheap electric energy available at night.
A conduit or pipe system containing a fluid in the
liquid phase and having a relatively low boiling point, for
instance water, is arranged in heat transferring communication
between the heat exchanger and the heat accumulator body.
Circulation pumps are arranged in the piping system for
water transport between the accumulator body and the heat
exchanger and has on its suction side piping in flow communication
with an expansion vessel so as to withstand the maximum pressure.
A temperature sensing means is arranged in the system so that the
pump stops when the heat exchanger reaches a predetermined
temperature, thereby keeping in the piping in the accumulator body
dry vapour in a state of moderate pressure generated in the
expansion vessel. The temperature sensing means may be a room
thermostat which is used when the accumulator is connected to a
floor heating system.
Consequently, when the pump receives a start signal from
said temperature sensing means for renewed heat transfer between
the heat accumulator body and the heat exchanger, vapour is
instantly released from the accumulator to fill the piping. The
heat exchanger may have an expansion vessel of either open type or
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closed loop type to withstand the expansion pressure. The control
device of the pump preferably employs a thermostat or a thyristor
device for sensing the temperature of the water in the heat
exchanger system or at the inlet or outlet from the heat
exchanger.
The heat accumulator body is for instance manufactured
from a ceramics material having approximately the following
composition, comprising by weight 90% MgO, 4% CaO and different
kinds of oxides. The heat accumulator consists of ceramics
material and heating wires are placed in holes in the ceramics
material and connected in series to an electrical power supply .
The heat pipes are arranged in the heat accumulator body. The
heat accumulator body is covered with a thick insulator and is
coated with heat a reflective layer or a reflector film for better
heat conservation. Pipes are inserted into the heat accumulator
which pass water therethrough and exchange heat between the heat
accumulator body and a heat exchange system coupled thereto. The
circulation speed of circulation pumps is controlled by thermostat
or thyristor in the system in association with the temperature of
inlet pipe or the temperature difference between input and output.
The present invention provides a heat accumulator of the
type having a heating block fabricated of a material having a high
thermal conductivity, and including electric heating wires located
therein for heating said block, said heating wires adapted to be
connected to an electric power supply in operation, the block
provided with passageways extending therethrough and a heater
fluid tube extending through said passageways and being in thermal
contact with said block, the heater fluid tube having an entrance
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port and an exit port each located on the exterior of said block,
the accumulator being provided with an outer insulation layer
enveloping said block. The improvement comprises the accumulator
being provided with a thermally conductive packing material for
packing the space between the heater fluid tube outer side walls
and the passageway walls in said block thereby providing said
thermal contact, said packing material being selected from the
class of materials having suitable thermal expansion coefficients
whereby when the block is heated said packing material can
compensate for the difference in expansion between said block and
said heater fluid tube, the improvement further comprising the
heater fluid tubes located in said block being shaped and
dimensioned to form a gas-lock when a fluid circulation means
operably couplable to said accumulator is not pumping the heat
exchanger liquid.
BRIEF DESCRIPTION OF THE DRAWINGS
This invention will be more fully understood from the
detailed description given hereinbelow, reference being had to the
accompanying drawings which are given for purposes of illustration
only, and wherein:
Fig. 1 is a schematic drawing of heat accumulator
embodying the subject invention;
Fig. 2 is a sectional view of pipe apparatus according
to this invention; and
Fig. 3 (A) (B) are schematic drawings of various
embodiments of pipes in heat accumulators according to the present
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invention.
* The numerals in the drawings indicate the following
elements.
Numeral 1 indicates a heat accumulator, numeral 2
indicates an electric heating wire, numeral 3 and 8 indicate a
pipe, numeral 4 indicates an adiabatic material, numerals 5 and 6
indicate circulation pumps, numeral 18 represents a steam
condensing apparatus, numeral 7 represents an assistant heat
accumulating tank, numeral 30 represents a hot water tank, numeral
16 represents a radiator, numeral 20 represents a control unit,
numeral 24 represents a thermostat, numeral 14 represents heat
accumulating, numeral 25 represents an expansion chamber, numeral
17 represents a connector, and numeral 19 represents a cold water
valve.
DETAILED DESCRIPTION OF THE lNv~ loN
Figure 1 illustrates a schematic drawing of the heat
system 14 forming the present invention which includes a heat
accumulator (1) and a heat exchanger such as shown at 7, 30 or 16
coupled thereto. The heat accumulating material in heat
accumulator (1) is heated by an array of electric heating wires
(2) connected to a control unit (20) controlling the electrical
power supply. The heat accumulator (1) can be heated to 600 and
up to 850C if desired. The heat is stored in a heat accumulating
material such as cast iron or ceramics.
For use of the stored heat, the water in pipes (3) in
the heat accumulator (1) is circulated by the operation of
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circulation pumps (5) and (6) and the heat accumulated in heat
accumulator (1) is delivered from a steam condensing apparatus
(18) to hot water tank (30) through pipes (3). Cold water which
is admitted to the hot water tank (30) through inlet (34) is
heated by the hot water in pipe (3) with the help of propeller (9?
and supplied from outlet (35) to the kitchen or bathroom or other
locations. The pipe (3) may also be connected to a radiator (16)
so as to heat a bedroom or livingroom. An expansion chamber (25)
may be installed in a closed type in pipe (3) or separately in an
open type on the outside.
The circulation pumps (5) and (6) supply low-temperature
water to the heat accumulator (1). The control unit (20) which
also controls night electric supply constitutes a heat
accumulating system (14) with heat accumulator 1. In case of
being heated beyond the capacity of heat accumulator (1) or upward
of 850C, the excess heat is stored in an auxiliary heat
accumulating rank 7 which may be provided in plurality to increase
the capacity of heat accumulation. Heat accumulators (1) can be
connected serially or in parallel in accordance with the size of
house or heating space to control the capacity of heat storing.
In this invention, pipe (3) in the heat accumulator (1)
can be heated up to 600C even sometimes up 850C and is
dimensioned and shaped to have arcuate bent portions embedded in
accumulator (1) which helps to maintain the steam on top of the
heat accumulator (1) when the liquid pumps are off. In this way,
a gas-lock or steam cover is formed in accumulator (1) thereby
preventing fluid circulation when pumps (5) and (6) are switched
off. This results in quieter operation when no fluid is being
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circulated. This gas-lock advantageously ensures that the heat
exchange fluid is always present in the liquid state in the pumps,
thereby ensuring that the pumps can start instantaneously.
The steam can absorb high-temperature hèat from the
vicinity of the pipe and the temperature of the water in the pipe
(3) is controlled to correspond to that of the water in hot water
tank (30) and in heat accumulator (1) and to keep the
predetermined temperature by the operation of thermostat ('24)(33).
As the temperature of the water decreases, the speed of
circulation pump (6) is increased to maintain the predetermined
temperature of the water, for example 70C.
According to this invention a high heat capacity powder
3b can be filled in the hole (3a) between pipe (3) and accumulator
material (1) to allow for the differential expansion of the pipes
and heat accumulator with temperature change, best seen in Figure
2. The high heat capacity powder (3b) is made for example of
copper, cement powder or silicon carbide, which can accommodate
the difference of the temperature expansion coefficients between
the different materials thereby protecting against thermal stress
hazards such as cracking or breaking of the heat accumulator (1)
in the heat exchange system in accordance with the present
invention. The heat exchange fluid in pipes (3) may be a heat
transfer liquid material having a high boiling point or a low
boiling point.
This invention also provides pipe connectors (17) (17')
between the inlet and outlet of the heat accumulator (1) which may
be made of ceramics, porcelain or other thermally and electrically
insulating materials to protect against heat loss and electrical
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leakage.
Various embodiments of installation according to this
invention are shown in Fig. 3 (A) and (B), to install pipes (3)
vertically or horizontally in the heat accumulating system which
can be used in accordance with the place and status effectively.
The heating system (14) according to this invention may comprise a
plurality of heat exchanges such as heating machine (16) connected
to heat accumulator (1). Several systems may be arranged in
series or parallel depending on the size of the building or house.
The pipe apparatus (3) of heat accumulator (1) according
to the present invention have demonstrated long lifetimes without
exhibiting cracks or breaks on account of the difference of
expansion-contraction coefficients between different materials at
the high temperatures. Also, this apparatus may be installed
vertically or horizontally and may be adapted to the conditions of
various envlronments.
While the pipe apparatus and associated heat accumulator
of the present invention has been described and illustrated with
respect to the various embodiments disclosed herein, it will be
appreciated that numerous variations of the embodiments may be
made without departing from the scope of the invention.
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