AU601907B2 - Latent heat storage capsules containing heat-storage composition and temperature control apparatus using said capsules - Google Patents

Description

I j a3 COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 a COMPLETE SPECIFICATI (Original) FOR OFFICE USE Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: 'Priority: SRelated Art: e C This document contains the amendmen ts made undr

I

Sectiuon 49 arid is corrCL for pril t ing.

t t t r Name of Applicant:

C

Address of Applicant: I r iActual Inventor(s): Address for Service: Address for Service: KUBOTA TEKKO KABUSHIKI KAISHA 2-47, Shikitsu-higashi 1-chome, Naniwa-ku, Osaka-shi, Osaka-fu,

JAPAN.

Naomichi YANO Tadatsugu UENO Shigeru TSUBOI DAVIES COLLISON, Patent Attorneys, 1 Little Collins Street, Melbourne, 3000.

Complete specification for the invention entitled: "LATENT HEAT STORAGE CAPSULES CONTAINING HEAT-STORAGE COMPOSITION AND TEMPERATURE CONTROL APPARATUS USING SAID CAPSULES" The following statement is a full description of this invention, including the best method of performing it known to us 1 i-' 2 "LATENT HEAT STORAGE CAPSULES CONTAINING HEAT-STORAGE COMPOSITION AND TEMPERATURE CONTROL APPARATUS USING SAID CAPSULES" BACKGROUND OF THE INVENTION Field of the Invention This invention relates to a heat storage means for use in- greenhouses for facility horticulture or cultivation, in living area heating, in chemical heat pumps, further in solar energy Sstorage tanks and industrial waste heat recovery facilities, and in other fields, and is particularly concerned with latent heat storage capsules improved such that heat-storage and release characterisitics of a heat-storage composition contained therein can be utilized to the nmaxn extent, and to a 1-I 3 temperature control apparatus in which said capsules may be used efficiently in temperature control in various hothouses and the like.

Background Art The use of latent heat-storage capsules with a latent heat-storage material capable of thermal phase change, namely a phase-change material, sealed therein (hereinafter, "PCM capsules") as heat sources for various purposes has been proposed, for example i for storing solar energy therein for later heat radiation for heating purposes or, more broadly, for storing solar energy in summer for emission in winter for various heating purposes. Such PCM capsules are under way for practical use.

As the above-mentioned PCM capsules, there are known spherical ones Japanese Utility Model Application No. 109283/83) and flat ones (e.g.

Japanese Utility Model Application No. 105796/84), among others. From the viewpoints of ease in placing, ease in forced circulation of a heat transfer medium in heat exchange, and so forth, the latter flat PCM capsules may be said to be morei advantageous.

In particular, for heat exchange between PCM capsules and air as a heat transfer medium flat PCM capsules are preferable.

However, flat PCM capsules are very small in thickness as compared with the other dimensions, length and breadth, so that when they are in the Li 4 vertical disposition, the latent heat-storage material, for example crystalline calcium chloride (CaC 2.6H20), or a nucleating agent therefor contained in the flat PCM capsules, precipitates on the container bottom, whereupon the crystal growth owing to the nucleating agent, namely the phase change of the latent heat-storage material, cannot be promoted in a uniform manner any more, hence disadvantageously, the heat-storage effect cannot be produced to a satisfactory extent.

It is conceivable that horizontal disposition of flat PCM capsules might solve such S' problem.

In that case, the nucleating agent is dispersed uniformly and generally over the flat c bottom portion of the flat PCM capsules and this S favorably causes uniform phase change in the latent heat-storage material. However, when the temperature of the flat PCM capsules is lower than that of air and thus there is a temperature difference from the air in the stage of heat storing, dew condensation can easily occur on the flat PCM capsule surface.

The water resulting from this dew condensation can 1 hardly be discharged and moreover that portion of heat which is consumed for the vaporization of this water is directly reflected in a disadvantageously reduced heat-storage efficiency.

Furthermore, in using PCM capsules in temperature control apparatus for use in various hothouses and the like, it is necessary to provide a separate heating unit in addition to the PCM capsules l j 5 so that the shortage of heat as resulting from insufficient heating, for example in winter when the duration of sunshine is short, can be filled up. When such a heating unit is used combinedly, heat radiation from said unit can hardly extend over the whole hothouse and this readily results in lack of uniformity in temperature within the hothouse. For avoiding such trouble, a blower is required for circulating the air within the hothouse to thereby cause the heat radiated extend over the whole hothouse.

SUMMARY OF THE INVENTION S; An object of the invention is to provide a flat PCM I 15 capsule which contains heat storage composition in the sealed state, has an improved structure and makes it possible for the heat storage/release characteristics of the heat storage composition to be utilized efficiently.

According to the present invention there is provided a flat latent heat storage capsule which is adapted to be supported vertically in use and which comprises a a rectangular plate-like hollow vessel defined by opposed faces which are sealed together at their peripheral edges, the interior of the vessel having a plurality of 0"4 horizontally extending elongate webs each extending from a Is 4 4 o i one of the opposed faces to the other to define an upwardly directed surface within the interior of the vessel, a plurality of openings passing through the 30 hollow vessel in the thickness direction thereof and i sealed from the interior of the vessel, at least one continuous groove-like recess which extends between the upper and lower pierpheral edges of the vessel on the outer surface of each face adjacent each end thereof, and j a protrusion in the neighborhood of each of the four corners of each face of the vessel, the protrusions on each face being opposed to the protrusions on the '7 O 7.,phhspe.o06.kubota.spe.5 i *motio -6opposite face, and wherein the hollow vessel contains a latent heat storage composition capable of thermal phase change.

Further according to the present invention there is provided a temperature control apparatus for use in a structure such as a hothouse which comprises a housing, a heat storage unit in the housing and equipped with plural units of the flat latent heat storage capsule described in the immediately preceding paragraph, inlet means to tthe housing, outlet means from the housing, a blower unit for introducing air within the structure through the inlet means into said housing, passing the same through 0 4 0. said heat storage unit and emitting the same through the 0 0 15 outlet means out of said housing, and a heating unit for 0 heating the air introduced into said housing by said 0 blower unit and disposed in the flow path of the air current caused by the blower unit between the heat storage unit and the outlet means.

U" 0000 Any heat storage composition may be incorporated in the flat latent heat storage capsule, for example sodium o, sulphate decahydrate, but calcium chloride hexahydrate compositions are preferred.

00o When a heat storage composition consisting o substantially of calcium chloride hexahydrate alone is cooled from the molten state, it does not begin to A 7 .'c06627.hhspe.006,kubotaspe,6

JAL-

7 solidify even after passage across its solidification point (about 29.5 0 C) but begins to solidify rapidly at about 200C, for instance. The degree of such supercooling varies greatly depending on the rate of cooling and the extent of disturbance of the melt, among others, so that the temperature at which the latent heat is released cannot be specified.

Accordingly, the temperature control in response to a desired temperature cannot but become imprecise.

When a nucleating agent for preventing supercooling, for example strontium chloride hexahydrate, is added a to the composition in an amount of about 5 percent by weight, the phenomenon of supercooling is much (t1" inhibited and the degree of supercooling is reduced to about 3-4 0 C. However, such supercooling inhibiting effect of known nucleating agents cannot be said to be fully satisfactory although the optional addition level differs only to some extent depending on the kind of nucleating agent. Thus, with known nucleating agents supercooling cannot be controlled sufficiently within an acceptable range.

I ,After a number of experiments with various compounds, the present inventors confirmed that the phenomenon of supercooling can be suppressed very effectively by using barium sulfide and barium chloride dihydrate combinedly in certain specific amounts. It was further found that, as will be described later in the examples, the coexistence, in a heat storage composition containing calcium chloride hexahydrate as the main component, of 0.001-5 percent of barium sulfide and 0.05-5 percent of barium chloride dihydrate can suppress the supercooling to at most 20C. When the amount of hI -Sp 8 barium sulfide or barium chloride dihydrate is lower than the lowest limit given above, the synergistic supercooling inhibiting effect arising from their combined use cannot be expected any more but only an incomplete supercooling inhibiting effect (supercooling of about 5-6°C) as obtainable by their single use can be produced. On the other hand, when the contents of the above two additives exceed the respective upper limits, solidification does not occur in some instances or the quantity of latent heat decreases greatly, so that the performance and stability of the heat storage material deteriorate.

sml l In a further study, it was found that when a small amount of strontium chloride is used in combination with barium sulfide and barium chloride dihydrate, a satisfactory supercooling inhibiting II ii effect can be secured even at a further reduced total nucleating agent addition level. In view of such Slexcellent supercooling inhibiting effect of strontium ,j chloride hexahydrate, it was considered whether a satisfactory supercooling inhibiting effect might be still obtained even when one of barium chloride or barium sulfide is omitted, and investigations were conducted in this direction in an attempt to omit the t, s, use of barium sulfide which can be a source of hydrogen sulfide. As a result, it was found that a .satisfactory supercooling inhibiting effect can be produced when strontium chloride hexahydrate and a slightly increased amount of barium chloride are used combinedly. Thus, the most preferred heat storage composition contains calcium chloride hexahydrate as i the main component and as nucleating agents for preventing supercooling, 0-5 percent by weight (on s f -i i~~i II r-rrrr~UWlul~ 9 the whole heat storage composition basis) of barium sulfide, 0.001-5 percent by weight (on the same basis) of barium chloride dihydrate and 0.001-0.1 percent by weight (on the same basis) of strontium chloride hexahydrate.. Such a composition is described in detail and claimed in our co-pending application 55769/86 from which this application is divided. The whole contents of application 55769/86 are incorporated herein by reference.

More generally, in the preferred heat storage composition, the contents of barium sulfide and barium chloride dihydrate as nucleating agents t can be reduced to 0.0001-5 percent and 0.001-5 percent, respectively by adding 0.001-0.1 percent of strontium chloride hexahydrate as an additional nucleating agent to the whole heat storage composition. When strontium chloride hexahydrate is used in an amount of not less than 0.06 percent, barium chloride dihydrate can be combined with it alone as another nucleating agent in an amount of not less than 0.5 percent to produce a satisfactory I supercooling inhibiting effect. The supercooling inhibiting effect is dependable and sufficient at very low nucleating agent addition levels if the levels of addition of the nucleating agents meet the conditions given immediately below.

Thus, the nucleating agent contents (or addition levels), X for barium sulfide, Y for barium chloride dihydrate and Z for strontium chloride hexahydrate, which are preferred are as follows: 0.00 0.00 when 0.06 Z X 1 Y 1 Z 0.1, and 0.1, then 0 and Y -i i when 0.005 Z 0.06, then X 0.0001 and Y 0.01, or [III] when 0.001 Z 0.005, then X 0.001 and Y 0.01.

As mentioned above, a heat storage composition which will cause substantially no supercooling phenomenon and has an optionally selected latent heat release temperature can be obtained by incorporating into a heat storage material mainly consisting of calcium chloride hexahydrate specific nucleating agents consisting of barium chloride and so on and further, optionally, a solidification point modifier, such as zinc chloride, potassium bromide, sodium bromide or ammonium bromide. Upon repeated use, namely after multiple repetition of the solidification-melting cycle, even this heat storage composition may sometimes deteriorate in its performance as a result of precipitation of part of said nucleating agent or solidification point modifier as crystals. In such case, however, the dispersion stability of the whole heat storage composition can be markedly improved by incorporating into the heat storage composition an adequate amount of an ultrafine silica powder plus glycerin as a thickening agent. Preferably, wherein the ultrafine silica powder is present in an amount of 1.5-6 percent by weight and glycerin in an amount 1. ''Y 11 of 1-5 percent by weight.

As said ultrafine silica powder, there may be used, for example, a high purity ultrafine silica powder, such as Aerosil (trademark) of Degussa, West Germany. Supposedly, such substance exhibits its thixotropic property owing to the action of the silanol group (=Si-OH) which said substance has in its structure. Said substance occurs as very minute particles (7-40 pm) and is highly dispersible in various media. Thus, when incorporated into the heat storage composition, said substance is dispersed uniformly while maintaining the fine particulate state. It is presumable that, upon melting of said composition, particles of said substance are connected with one another by forming crosslinks and that, as a result, a thickening effect is produced.

Ultrafine silica powders have so far been used as thickening agents for paints or as sagging or running inhibitors for paints for thick coating of walls, among others, and their thickening effect is well known. Hithertofore, however, tiere have been c no instances of their use as thickening agents for heat storage compositions.

The present inventors have confirmed that 4. j ultrafine silica powders produce excellent thickening effect in heat storage compositions which are in the molten state and are very stable both chemically and physically and little susceptible to different heat storage compositions or to environmental conditions, such as heat. Thus, addition in relatively small amounts of an ultrafine silica powder as a thickening i. 1Y 12 agent together with glycerin to a heat storage composition whose main component is an inorganic substance in a hydrate form and which may optionally contain a solidii'cation point modifier and/or a nucleation promoting agent gives a necessary and sufficient viscosity. Moreover, an ultrafine silica powder does not aggregate or cake or otherwise degrade even after repetition of the heat storage-release cycle. Furthermore, the addition of i glycerin does not affect the solidification point since a low level of addition of glycerin is already sufficient. Therefore, the heat storage composition with an ultrafine silica powder and glycerin incorporated therein as thickening agents exhibits excellent repetition stability, reveals no :on-uniform dispersion or phase separation phenomenon, and can maintain a high level of dispersion stability for a prolonged period of time.

Referring again to the flat latent heat storage capsule, preferably an inlet of the hollow vessel for t.e heat storage composition is sealed, after charging with said composition, with a stopper by fit-fusion bonding, said stopper comprising a rod having a length substantially equal to the vessel wall thickness at said inlet as measured in the direction of the depth of said inlet.. The stopper ~may comprise a head which is generally disc-shaped and is integrally formed with the rod. Such head may include an annular skirt provided on that side of the head from which the rod projects.

AMr- 12a- The opposed faces of the flat capsule are conveniently bonded together to form the hollow vessel. This permits each face to be readily formed by blow molding. The openings passing through the hollow vessel may be defined by recesses in each face, each said recess being formed with a bottom surface which is bonded to the opposed face with a portion of the bottom surface and of the opposed face being punched from the hollow vessel. A lower exterior surface of each opening may slant downwardly and outwardly to permit moisture run-off from the opening.

The horizontally extending elongate webs are conveniently defined by corresponding recesses in the opposed faces with each said recess having an exterior lower surface which slants downwardly and outwardly to permit moisture run-off from the recess.

900627,hsIje 006.kuboa.pe.12

A

13 BRIEF DESCRIPTION Il OF THE DRAWINGS i 1 ii

I

One embodiment of a flat latent heat storage capsule in accordance with the present invention will now be described by way of example only with reference to the accompanying drawings, in which: Figure 1 is a plan view illustrating the embodiment of the heat s'orage capsule according to the invention; Figure 2 is a cross-sectional view of said examp'.e as seen along the line III-IIl in Figure 1; Figure 3 shows enlarged partial cross-sectional views of said example, Figure 3A along the line A-A, Figure 3B along the line B-B, and Figure 3C along the line C-C in Figure 2; Figure 4 illustrates one arrangement in which the heat storage capsules of Figures 1 to 3 may be used; Figure 5 is a cross-sectional front view showing an example of temperature control apparatus incorporating the capsules of Figures 1 to 3; Figure 6 is a cross-sectional side view of the apparatus shown in Figure Figure 7 is a cross-sectional view of the same apparatus as seen along the line VIII-VIII in Figure 6; Figure 8 illustrates one arrangement in which the temperature control apparatus shown in Figures 5 to 7 may be used; Figure 9 is a cross-sectional front view of another example of the temperature control apparatus; Figure 10 is a cross-sectional side view of a further example of the temperature control apparatus; t Figures 11A and 11B are enlarged partial cross-sectional views which schematically illustrate -r LL~uliur~ .L I LALA.L I Lkj L"X AJ _OL- &=IJkJ.L1jt.L1ALJ L U J'611UWAL -14a fit-fusion technique as applied to the inlet of the capsule of Figures 1 to 3 after heat storage composition charging; and Figures 12A and 12B are enlarged partial cross-sectional views which schematically illustrate another fit-fusion technique as applied to the inlet after charging of a heat storage composition.

DETAILED DESCRIPTION OF THE DRAWINGS T The flat PCM capsule 1 shown in Figures 1 to 3 comprises a rectangular plate-like hollow vessel comprising opposed face plates 10A and 1OB formed by blow molding. The vessel 10 has a plurality of oblong and circular recesses 11 and 12 respectively, defined by respective slant faces 11B and 12B. The vessel 10 is formed by bonding together by fusion the peripheral edges of the face plates bOA and b0B and the bottoms 11A and 12A of the recesses at corresponding sites on both face plates 10A and 1OB (Figures 2 and 3A).

A plurality of circular openings 13 are formed from the circular recesses 12 by punching out at least part of the fused bottoms 1Z.A of said circular recesses 12. The 125 circular holes 13 thus pass through the hollow vessel in the thickness direction thereof.

In the neighborhood of each end portion 14A and 14B of 3 each face plate, the hollow vessel has at least one 30 continuous groove-like recess i5 (two are shown) extending from one peripheral edge to the other in a perpendicular direction to the length of the recesses lb.

In the neighborhood of each of the four corners 14C... b4C, there is provided a protrusion 16. The four protrusions 16 on each face plate serve as spacers and are opposed to the protrusions on the opposite face plate .PhhsPe.006.kubotaspe. 14 15 (Figure 2).

The vessel is sealable after charging the hollow space with a latent heat storage composition B, which may contain a nucleating agent B 2 and other additives as described in our co-pending patent 587,243.

i In Figure 1, 17 indicates an inlet for the latent heat storage composition B 1 After charging, the inlet is hermetically closed by thermal fusion or stoppering.

In Figure i, 18...18 indicate compressed portions at the corners of the flat PCM capsule 10, which are to serve as fenders for preventing breakage of the PCM capsule due to collision with some other body and also to serve to avoid formation of narrow areas within the inside space. On the drawing, the compressed portions 18 are found only at the bottom corners although such may be provided at all four corners.

In practical use, plural units of this flat PCM capsule are vertically disposed in parallel with one another, as shown in Figure 4. On that occasion every two neighboring capsules, owing to butting of their spacing protrusions 16...16, leave a space therebetween so that air can be forcedly circulated through this space.

Within the hollow vessel 10 in the flat PCM capsule i, each oblong recess 11 forms a web or shelf 11' [Figure 3A], so that the nucleating agent B 2 and other additives can deposit on such shelf 11'. As a result, concentrated local accumulation of such additives can be prevented and heat storage can be performed effectively. Furthermore, the presence of the holes 13 makes the flow of air complicated and 27.,PhhsDe.06.kubota.spe15 (1- 16 this leads to an increase in effective heat exchange surface area.

Even when dew condensation occurs on the surface of the PCM capsule 1 due to a temperature difference relative to the ambient temperature, the condensate water is put aside by the air blown under forced circulation in the direction indicated by the arrow x and eventually arrives at the grooves 15, and flows down therein without difficulty.

Similarly, when dew condensation occurs in the recesses 11 and 12, the condensate water readily flows down the recess inside surface which is slanting, whereby the condensate water retention is effectively inhibited.

The heat storage composition may be introduced into the flat capsule 1 by heating to melting and then pouring it in the liquid form into the hollow vessel 10 through an inlet 17, which, after charging, is tightly stoppered. An advisable stoppering means is as follows: As shown in Figure 11A and Figure 11B, which are enlarged cross-sectional partial views schematically illustrating an example of the means of tightly stoppering the inlet 17, the inlet 17 is formed such that the opening end slightly protrudes and shows a gradual expansion toward the exterior. The stopper which is formed like a wine bottle stopper, preferably, comprises a disc segment 35a and a rod segment 35b formed solidly with said disc segment and protruding from the middle of said disc segment. (said rod segment being capable of exactly fitting the above-mentioned inlet 17 and the length -i 4 17 of said rod segment 35b being substantially equal to the depth of the inlet). For fitting and fusion together between the inlet 17 and stopper 35, said stopper 35 is pushed into the inlet 17 while it is rotated at high velocity, as shown in Figure 11A.

The portions of the stopper 35 and the inlet 17 which are in contact with each other are welded together as a result of friction heating. After cooling, there can be achieved complete closure of the inlet, as shown in Figure 11B. As another means of effecting fit-welding, the technique comprising melting the fitting surface of each of the inlet 17 and stopper by heating and quickly fitting the stopper into the inlet can also be employed. It goes without saying that the means of closure by fusion such as mentioned above is applicable to those cases in which a thermoplastic material such as a synthetic resin is i used as the vessel material.

Figures 12A and 12B, which are enlarged partial cross-sectional views, illustrate another fit-fusion technique. The stopper 35 has a ring-shaped protrusion or annular skirt 35c on that side of the disc segment 35a which carried the rod segment 35b. The fit-fusion welding is conducted in the same manner as described with reference to Figures 11A and liB. When such means is employed, W the circumferential surface of the rod segment the lower surface of the disc segment 35a, the lower surface ot the disc segment 35a and the inner circumferential surface of the ring-shaped protrusion are all fusion-bonded to the opening wall of the inlet 17, so that an increased sealing length can be attained, hence the sealing effect can be further V1 K>

-I

1 heightened.

I

T-:

The flat latent heat storage capsule described herein may have any heat storage composition. However, a heat storage composition in accordance with the invention described and claimed in our co-pending application 55769/86, when used in combination with a capsule having such geometric characteristics as mentioned abo'_, gives a very good latent heat storage capsule with which the excellent heat storage-release characteristics of the heat storage composition as well as the geometric characteristics of the capsule body can be exhibited effectively.

A temperature control apparatus in which a plurality of flat latent heat storage capsules such as described above are used is now described.

Figures 5 to 7 illustrate an example of the temperature control apparatus in which flat PCM capsules with a heat storage composition sealed therein are built in. In this temperature control apparatus, a heat storage unit 22 comprises upper and lower rows of flat PCM capsules 1 each containing the heat storage composition. In each row, the capsules are arranged in the vertical standing position and in parallel with one another in a holding frame 20, with a space for air passage retained between any two horizontally neighboring capsules. This heat storage unit 22 and a heating unit 23, which comprises a burner unit 23a and a pipe-made heat exchange unit 23b, are built in a hollow housing 26 provided with an air inlet 24 on the top and four air outlets 25 in ul- -ii-~id-.

the lowermost part. A fan-top blower 27 is provided at said air inlet 24 so that air outside the housing can be introduced into the housing through the air inlet 24 and, after passage through said heat storage unit 22 and said heating unit 23, sent out of the housing via the air outlets 25. This temperature control apparatus is placed, as shown in Figure 8 which illustrates how to use it, within a hothouse 28 or the like for cultivating various farm products such as tomato and melon, which is a plastic film house or a glasshouse, for instance. The chimney 29 of the heating unit 23 is arranged such that it protrudes out of the hothouse 28 for allowing the waste combustion gas to go out of the house. In this r way, the inside temperature of the hothouse 28 is controlled.

C, Thus, the air within the hothouse is Scirculated through the inside and outside of the apparatus housing 26 by means of the blower 27.

During shining hours, solar energy is supplied to the heat storage unit 22 via the air within the hothouse and each heat storage capsule 1 absorbs and stores that portion of solar energy which remains after heating of the hothouse to thereby maintain the temperature within the hothouse at an adequate level. After sunset, the air in the hothouse is heated within the apparatus 26 by the heat storage capsules 1 so that the hothouse temperature can be maintained at an adequate level. In case heating by the heat storage unit 22 is insufficient, an oil burner 21 is automatically or manually actuated so that the hothouse air introduced into the apparatus 26 can be heated by means of the heating unit 23 to Ii; i thereby maintain the hothouse temperature at an adequate level.

As shown in Figure 5 and Figure 6, the heating unit is disposed downstream (with respect the air current caused by the blower 27) from th( heat storage unit 22, so that the air heated by t heating unit 23 will not pass through the heat storage unit 22 or, in other words, the air will leave the apparatus 26 without temperature fall to heat absorption by the heat storage capsules J In this way, it is now possible to condL the hothouse heating in case of insufficient heat by the heat storage unit efficiently with a mini heat loss in the heat storage unit while suppress the uneveness in temperature to a possible minimu means of the blower. In addition, the blower can used for both heat-storing and heating purposes a therefore the apparatus is advantageous from both I €c4-ran-irntl1 onAr nc- T4 Tarnn n4c above Sto :he lue i.

ict :ing mum ing im by be nd the

IA

A~4' UC U~LUL~L C111 ~VL L L'W &I In designing the temperature control apparatus, other constructions than that shown in Figures 5 to 7 may also be employed, for example the construction shown in Figure 9 in which the lower set of heat storage capsules 1 involves only one row or the construction shown in Figure 10 in which the air inlet 24, heat storage unit 22, heating unit 23 and air outlet 25 are arranged in parallel as viewed in the horizontal direction.

The described heat storage capsules which sealedly contain a heat storage composition may r. r si 21 a 21 F: ensure the dispersion of any nucleating agents which serve to promote phase transition of the heat storage composition and makes it possible for the dew condensate surface water possibly appearing during heat release to flow down easily, so that the heat storage and release effects can be produced with a maximum efficiency. Each capsule is wholly integral inclusive of recesses, an advantage which may be provided by fusion bonding. Furthermore, the grooves for drainage also serve as reinforcing ribs, so that the strength of the capsule itself is also improved.

The described temperature control apparatus constructed by building the above heat storage capsules therein, if in short supply of heat due to insufficiency of the quantity of heat released by heat storage capsule groups, can assuredly get supplementary heat supply by means of the heating unit and blower unit and, furthermore, the heat storage and release effects of the heat storage capsule groups can be produced efficiently without causing great heat losses.

A

ii ii yu- 'th-I

Claims (14)

1. A flat latent heat storage capsule which is adapted to be supported vertically in use and which comprises a rectangular plate-like hollow vessel defined by opposed faces which are sealed together at their peripheral edges, the interior of the vessel having a plurality of horizontally extending elongate webs each extending from one of the opposed faces to the other to define an upwardly directed surface within the interior of the vessel, a plurality of openings passing through the hollow vessel in the thickness direction thereof and sealed from the interior of the vessel, at least one o° continuous groove-like recess which extends between the '44 upper and lower pierpheral edges of the vessel on the outer surface of each face adjacent each end thereof, and o^ 1 a protrusion in the neighborhood of each of the four on o corners of each face of the vessel, the protrusions on S° each face being opposed to the protrusions on the opposite face, and wherein the hollow vessel contains a latent heat storage composition capable of thermal phase change. 0o 0 2. A flat latent heat storage capsule according to SClaim 1 wherein the heat storage composition contains 0 0 0 s calcium chloride hexahydrate as the main component and, as nucleating agents for preventing supercooling, 0.001-5 B, weight percent of barium sulfide and 0.05-5 weight So 0" percent of barium chloride dihydrate.

3. A flat latent heat storage capsule according to Claim 1 wherein the heat storage composition contains calcium chloride hexahydrate as the main component and as nucleating agents for preventing supercooling, percent by weight (on the whole heat storage composition basis) of barium sulfide, 0.001-5 percent by weight (on the same basis) of barium chloride dihydrate and 6627 pllIlSpe. 006.k uboa, spe.22 S\90062.pl b -23 I0.001-0.1 percent by weight (on the same basis) of strontium chloride hexahydrate.

4. A flat latent heat storage capsule according to 1 Claim 3 wherein in the heat storage composition the barium sulfide content (X weight percent), barium chloride dihydrate content (Y weight percent) and strontium chloride hexahydrate content (Z weight percent) further satisfy the following conditions: when 0.06 Z 0.1, then l X 0 and Y 0., when 0.005 Z 0.06, then i X 0.0001 and Y 0.01, or when 0.001 Z 0.005, then X 0.001 and Y 0.01. I A flat latent heat storage capsule according to any one of Claims 2 to 4 wherein heat storage composition further contains at least one bromide selected from the group consisting of potassium bromide, sodium bromide and ammonium bromide as a solidification point modifier.

6. A flat latent heat storage capsule according to any one of Claims 2 to 5 wherein the heat storage composition additionally contains ultrafine silica powder and glycerin as thickening agents.

7. A flat latent heat storage capsule according to Claim 5 wherein the ultrafine silica powder is present in an amount of 1.5-6 percent by weight and glycerin in an amount of 1-5 percent by weight.

8. The flat latent heat storage capsule of any one of SI 900627.phhspe.006,kubota.spe, 23 u V----YII^IU C~~ 24 the preceding claims wherein an inlet of the hollow vessel for the heat storage composition is sealed, after charging with said composition, with a stopper by fit-fusion bonding, said stopper comprising a rod having a length substantially equal to the vessel wall thickness at said inlet as measured in the direction of the depth of said inlet.

9. The flat latent heat storage capsule of Claim 8, wherein the stopper comprises a head which is generally disc-shaped and is integrally formed with the rod. The flat latent heat storage capsule of Claim 9, wherein the disc-shaped head has an annular skirt provided on that side of the head which carries said rod. S11. A flat latent heat storage capsule according to any one of the preceding claims wherein the opposed faces are bonded together to form the hollow vessel.

12. A flat latent heat storage capsule according to Claim 11 wherein the openings passing through the hollow vessel are defineL by recesses in each face, each said recess being formed with a bottom surface which is bonded to the opposed face with a portion of said bottom surface and of the opposed face being punched from the hollow vessel. I

13. A flat latent heat storage vessel according to Claim 11 or Claim 12 wherein each face is formed by blow molding.

14. A flat latent heat storage capsule according to any one of the preceding claims wherein each opening is circular. D 15. A flat latent heat storage capsule according to any 900627, phl spe.006, kubot a. spe, 24 tI, 25 one of the preceding claims wherein each groove-like recess extends vertically.

16. A flat latent heat storage capsule according to any one of the preceding claims wherein the horizontally extending elongate -ebs are defined by corresponding recesses in the opposed faces and wherein each said recess has an exterior lower surface which slants downwardly and outwardly.

17. A flat latent heat storage capsule substantially as herein described with reference to the accompanying drawings.

18. A temperature control apparatus for use in a structure such as a hothouse which comprises a housing, a heat storage unit in the housing and equipped with plural units of the flat latent heat storage capsule of any one of the preceding claims, inlet means to the housing, outlet means from the housing, a blower unit for introducing air within the structure through the inlet means into said housing, passing the same through said heat storage unit and emitting the same through the outlet means out of said housing, and a heating unit for heating the air introduced into said housing by said blower unit and disposed in the flow path of the air current caused by the blower unit between the heat storage unit and the outlet means. DATED this 27th day of June, 1990. KUBOTA TEKKO KABUSHIKI KAISHA By its Patent Attorneys DAVIES COLLISON Nh C

900627.phhspe.6kubotaspe. 25 4