Heat storage device

A heat storage device is disclosed in which grooves for supports supporting heat storage vessels, each vessel storing therein a heat storage material, are defined on the lower surface of each of the vessels so that the supports do not project from the bottom surface of each vessel.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to the construction of a heat storage device using a 
combination of a large number of heat storage vessels, each storing 
therein a heat storage material. 
2. Description of the Prior Art 
As disclosed, for example, in European Patent Application No. 0041386, a 
conventional heat storage device stores a sensible heat type heat storage 
material such as water or a latent heat type heat storage material such as 
polyethylene glycol or calcium chloride hexahydrate in each heat storage 
vessel made of plastic or metal. Usually, an aggregate of a large number 
of such heat storage vessels placed on supports is used as the heat 
storage device. A fluid such as air is caused to flow around each vessel 
in such a fashion that heat is applied from the fluid to the heat storage 
material through the outer surface of the vessel, or heat is taken in by 
the fluid from the heat storage material. Therefore, the heat storage 
vessels are arranged in such a manner as to define gaps between them 
through which the fluid flows. In order to make the heat storage device as 
a whole compact and to enlarge the heat storage capacity, the size of this 
gap is preferably as small as possible to such an extent that the fluid 
can flow therethrough. 
In a conventional heat storage device, however, the gap cannot be reduced 
because the interference of the supports for the heat storage vessels. 
Moreover, the supports impede the flow of the fluid, increase draft 
resistance and heat resistance and partly inhibit the reduction of size of 
the heat storage device. 
SUMMARY OF THE INVENTION 
In order to solve the problems of the conventional heat storage device 
described above, the present invention is directed to reduce the size and 
increase the capacity of a heat storage device by reducing the gaps 
between heat storage vessels without increasing draft resistance and heat 
resistance. 
A characterizing feature of one embodiment of the present invention resides 
in the following construction: Grooves for supports are disposed on the 
wall of each heat storage vessel so that the supports do not excessively 
protrude from the outer surface of the heat storage vessels, thereby 
narrowing the gaps between the heat storage vessels. Further, each vessel 
is given a curvature to disturb the flow of an external fluid, resulting 
in the reduction of its heat resistance. Thus, the construction of the 
heat storage device, as a whole, can be reduced in its size, and will 
exhibit an increased capacity. 
It will be appreciated that this construction disturbs the flow of an 
external fluid, decreases heat resistance, reduces the size of the heat 
storage device as a whole, but advantageously increases the capacity of 
the device. 
Another embodiment of the invention is characterized in that separate 
supports are eliminated and the heat storage vessels are each provided 
with spacer or support means in the form of projection or protrusion which 
support the vessel in a spaced-apart arrangement.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIGS. 1 and 2 show a heat storage vessel in accordance with one embodiment 
of the present invention. A plurality of grooves 6 are defined in parallel 
with each other on the wall of the heat storage vessel 1 made of metal or 
plastic to accommodate therein supports 4. According to this arrangement, 
the supports 4 do not project from the outer surface of the heat storage 
vessel 1, and the gap L between this vessel 1 and another 1' adjacent to 
the former in the vertical direction can be consequently reduced to that 
extent. Therefore, the size of a heat storage device consisting of a large 
number of these heat storage vessels (1,1',etc.) can be reduced. Since 
these grooves 6 are disposed in a certain spaced arrangement, the heat 
storage vessel 1 bears the weight of a heat storage material 3 and, hence, 
is apt to bend. FIG. 1 shows the case where the gap S between the supports 
4 is great, and the upper surface of the heat storage vessel 1 is curved 
in a recessed form. It is possible to reduce this gap S between the 
supports 4 and to let the upper surface of the vessel 1 curve in a convex 
manner. 
When a large number of heat storage vessels 1 are combined with one another 
and a fluid (such as air, water or the like) is caused to flow between the 
vessels 1, draft resistance due to the protrusion of the supports 4 can be 
reduced. Moreover, the flowing direction of the fluid is changed as 
represented by curved line F in FIG. 3. Therefore, turbulence occurs in 
the fluid, heat resistance from the heat storage vessel 1 to the fluid 
decreases while heat release from the fluid to the heat storage material 
or vice versa becomes easier, and reduction of the size of the heat 
storage device can be realized. When the heat storage vessel 1 is of a 
flat type, a practical size of the heat storage vessel, from the aspect of 
heat transfer rate and easy handling, is from 5 to 50 mm thick, from 100 
to 700 mm long and from 50 to 500 mm deep. When the heat storage vessel 1 
having such a practical size is curved, a suitable angle of inclination 
.theta., from the aspect of the rigidity of the heat storage vessel 1 and 
the draft resistance of the fluid, is in the range of 0.5 to 30 degrees. 
The heat resistance of such a heat storage vessel 1 can be reduced by 5 to 
30% when compared with the case where the vessel 1 is not curved at all 
(.theta.=0.degree.). The gap D between one vessel and adjacent vessels in 
the horizontal direction may be zero, but is preferably from 3 to 50 mm in 
practice for those heat storage vessels which have a size falling within 
the range described above. This is because the fluid generates drastic 
expansion and contraction at the portions of the gaps D and the flow of 
the fluid becomes turbulent. Experiments revealed that the heat resistance 
was further reduced by 3 to 15%. 
The vertical spacing or gap size L of the vertically adjacent vessels 
ranges from 1-20 mm and the preferred range of L is 3 to 10 mm. 
Preferably, the heat storage material 3 is not completely packed into the 
heat storage vessel 1, but is packed in such a fashion as to leave spaces 
8,8' in the vessel so that the heat storage vessel 1 can be bent more 
readily. The relative volume % of the space or spaces free of the material 
3 is in a range of from 5-15%; with about 10% being the best. 
FIGS. 5 and 6 show another embodiment of the present invention, in which 
the grooves 6 and the supports 4 are disposed in parallel with the 
longitudinal direction of the heat storage vessel 1. The fluid flows 
vertically with respect to the longitudinal direction of the vessel 1. In 
this embodiment, recess 5 is disposed symmetrically with a lid 2 with 
respect to the center P of the heat storage vessel 1, and the lid 2 of the 
adjacent vessel 1 above the vessel 1 is positioned so as to face the 
recess and, thus, to reduce the gap L in the vertical direction. 
FIGS. 7 and 8 show still another embodiment of the invention, in which a 
large number of thin grooves 7 are defined on the wall of the heat storage 
vessel 1 in parallel with the grooves 6 for supports. According to this 
arrangement, the fluid flowing in heat exchange relationship along the 
outer surface of the heat storage vessel 1 is more able to cause 
turbulence, the heat resistance can further be reduced, and the heat 
storage vessel 1 is easier to curve. The present invention can also be 
applied to the case where the heat storage vessel 1 is not equipped with 
the lids 2. 
FIGS. 9 and 10 show still another embodiment of the present invention, in 
which support or spacer means in the form of protrusions 10 are disposed 
on the lower surface B of the heat storage vessel 1 in place of the 
grooves in the foregoing embodiments so as to curve the vessel and to 
reduce the heat resistance. The lower end of each protrusion 10 is put on 
the upper surface A of another heat storage vessel 1' existing below the 
vessel 1. Therefore, the supports 4 that are arranged in the grooves 6 in 
the other embodiments can be omitted. Since the protrusions 10 exist in 
this embodiment, draft resistance due to the protrusions develops. From 
this aspect, it is preferable to reduce the size as well as number of 
protrusions 10. However, the protrusions 10 provide the following effect. 
When the fluid (e.g., air) flowing along the outer surface of the heat 
storage vessel 1 is extremely humid, moisture is gathered effectively to a 
desired position to enhance the heat storage effect. When heat is stored, 
the outer surfaces A, B of the heat storage vessel 1 are wet with dew, but 
the dew attaching to the lower surface B of the heat storage vessel 1 
moves along the protrusions 10 and flows to the upper surface A of another 
heat storage vessel 1' arranged below the vessel 1 (see FIG. 11). Heat 
transfer from the fluid to the heat storage material 3 during heat storage 
process is effected primarily through the lower surface B of the heat 
storage vessel 1 but not through the upper surface A. This is because the 
free spaces 8 exist inside the upper surface A and the heat storage 
material 3. Therefore, the dew deposited on the lower surface B of the 
heat storage vessel 1 should be removed as much as possible. This dew does 
not adversely affect the heat storage effect very much even when it is 
gathered on the upper surface A. To improve this effect, it is advisable 
to dispose a large number of thin grooves 7 such as shown in FIG. 8 or 
porous materials such as gauze or cloth at least on the lower surface B of 
a heat storage vessel. 
FIGS. 11 through 14 show still another embodiment of the present invention, 
in which the heat storage vessel 1 is structurally reinforced. If the 
number of protrusions 10 is small, concentrated load will be applied to 
the heat storage vessel of a lower stage so that this vessel will be 
broken. To eliminate this problem, the protrusions 10 in this embodiment 
are elongated in the horizontal direction in such a manner as to enlarge 
the surface coming into contact with the heat storage vessel of the lower 
stage. This also improves the dew removing effect. Furthermore, connection 
components 13 are formed by disposing recesses 11, 11' on the upper 
surface A of the heat storage vessel 1 and at the lower ends of 
protrusions 10, so that the vessel 1 is more easily bent. 
In this embodiment, the right and left ends of the heat storage vessel 1 
shown in FIG. 12 may be supported by separater supports (not shown) in 
order to curve the vessel 1 as shown in FIG. 10. In this instance, the 
vessel is easier to curve if the number of recesses 11, 11' is increased. 
It is also possible to curve in advance the heat storage vessel 1 by 
adjusting the number or capacity of the recesses 11, 11'. 
FIGS. 15 and 16 show still another embodiment of the invention, in which 
the angle of inclination .theta. is 0.degree.. FIGS. 17 and 18 show still 
another embodiment of the invention, in which the angle of inclination is 
also 0.degree.. 
According to these embodiments as illustrated, the supports do not project 
much from the outer surface of the heat storage vessel; hence, the 
vertical gap between the heat storage vessels can be reduced. 
It will be appreciated that the heat storage vessels in embodiments of the 
invention shown, for example, in FIG. 1, are formed of a flexible 
material, such as a thin metal or plastic sheet that will be deformed by 
the weight of the liquid heat storage material contained therein and by 
the location of the supports or spacer means.