JPH0215598B2 - - Google Patents
Info
- Publication number
- JPH0215598B2 JPH0215598B2 JP58012457A JP1245783A JPH0215598B2 JP H0215598 B2 JPH0215598 B2 JP H0215598B2 JP 58012457 A JP58012457 A JP 58012457A JP 1245783 A JP1245783 A JP 1245783A JP H0215598 B2 JPH0215598 B2 JP H0215598B2
- Authority
- JP
- Japan
- Prior art keywords
- heat storage
- temperature
- storage material
- sodium acetate
- acetate trihydrate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000005338 heat storage Methods 0.000 claims description 47
- 239000011232 storage material Substances 0.000 claims description 32
- 235000017281 sodium acetate Nutrition 0.000 claims description 19
- BDKLKNJTMLIAFE-UHFFFAOYSA-N 2-(3-fluorophenyl)-1,3-oxazole-4-carbaldehyde Chemical compound FC1=CC=CC(C=2OC=C(C=O)N=2)=C1 BDKLKNJTMLIAFE-UHFFFAOYSA-N 0.000 claims description 18
- 229940087562 sodium acetate trihydrate Drugs 0.000 claims description 18
- 239000002667 nucleating agent Substances 0.000 claims description 17
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 11
- 238000010438 heat treatment Methods 0.000 claims description 8
- AJPJDKMHJJGVTQ-UHFFFAOYSA-M sodium dihydrogen phosphate Chemical compound [Na+].OP(O)([O-])=O AJPJDKMHJJGVTQ-UHFFFAOYSA-M 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 7
- 239000001488 sodium phosphate Substances 0.000 claims description 7
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 claims description 7
- 229910000406 trisodium phosphate Inorganic materials 0.000 claims description 7
- 235000019801 trisodium phosphate Nutrition 0.000 claims description 7
- 238000007711 solidification Methods 0.000 description 16
- 230000008023 solidification Effects 0.000 description 16
- 230000008018 melting Effects 0.000 description 15
- 238000002844 melting Methods 0.000 description 15
- 238000004781 supercooling Methods 0.000 description 13
- 239000000463 material Substances 0.000 description 8
- 238000012360 testing method Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 239000007790 solid phase Substances 0.000 description 5
- 150000004677 hydrates Chemical class 0.000 description 4
- 238000001556 precipitation Methods 0.000 description 4
- VBJGJHBYWREJQD-UHFFFAOYSA-M sodium;dihydrogen phosphate;dihydrate Chemical compound O.O.[Na+].OP(O)([O-])=O VBJGJHBYWREJQD-UHFFFAOYSA-M 0.000 description 4
- ASTWEMOBIXQPPV-UHFFFAOYSA-K trisodium;phosphate;dodecahydrate Chemical compound O.O.O.O.O.O.O.O.O.O.O.O.[Na+].[Na+].[Na+].[O-]P([O-])([O-])=O ASTWEMOBIXQPPV-UHFFFAOYSA-K 0.000 description 4
- 239000007864 aqueous solution Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 230000006911 nucleation Effects 0.000 description 3
- 238000010899 nucleation Methods 0.000 description 3
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical class OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- VMHLLURERBWHNL-UHFFFAOYSA-M Sodium acetate Chemical compound [Na+].CC([O-])=O VMHLLURERBWHNL-UHFFFAOYSA-M 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 230000000977 initiatory effect Effects 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 238000004378 air conditioning Methods 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 150000008064 anhydrides Chemical class 0.000 description 1
- 229940040526 anhydrous sodium acetate Drugs 0.000 description 1
- 235000014113 dietary fatty acids Nutrition 0.000 description 1
- 230000003631 expected effect Effects 0.000 description 1
- 239000000194 fatty acid Substances 0.000 description 1
- 229930195729 fatty acid Natural products 0.000 description 1
- 150000004665 fatty acids Chemical class 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000011368 organic material Substances 0.000 description 1
- 239000012188 paraffin wax Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 239000001632 sodium acetate Substances 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 239000002918 waste heat Substances 0.000 description 1
Description
本発明は蓄熱材に関する。更に詳しくは、凝固
時の過冷却の程度に軽減し、長期の熱サイクルに
対し安定した性能を発揮する蓄熱材に関する。
蓄熱材としては、従来から水や砕石が用いられ
てきたが、これらは蓄熱密度が小さいため
（1cal／g.deg以下）、実用に際してはかなり大き
な蓄熱器を必要とする。また、放熱に伴つて、蓄
熱器内の温度は徐々に低下するので、安定な熱エ
ネルギーを得ることは、技術的にかなり困難であ
る。
これに対し、近年物質の融解、凝固の際の潜熱
を蓄熱に応用する研究、開発が盛んになつてきて
いる。このような潜熱型の蓄熱材の特徴は、材料
の融解温度に一致した一定温度の熱エネルギー
を、数10cal／ｇという高い蓄熱密度で安定に吸
収および放出できる点にある。
ところで、最近太陽熱利用技術や排熱回収技術
の進展に伴ない、給湯用および暖房用の熱源とし
て50〜60℃といつた比較的低い温度での蓄熱が注
目されている。このような低い温度で蓄熱を行な
う際の潜熱型蓄熱材としては、パラフインワツク
スや高級脂肪酸などの有機物や無機水和物などが
注目されている。
潜熱型蓄熱材としての有機物は、融解、凝固時
における安定性は良好であるものの、材料自身の
熱伝導が悪いため、熱の吸収および放出を行なう
上で問題がある。また、比重が小さいため、蓄熱
器も比較的大きなものとなつてくる。
一方、無機水和物は、有機物蓄熱材と比較して
熱伝導率は約２倍程よく、比重も1.5〜2.0程度と
大きいため、蓄熱器も小さくすることができる。
しかるに、無機水和物は、一般に凝固開始温度が
融解温度よりも低くなるという、いわゆる過冷却
現象を示す。かかる現象は、無機水和物を蓄熱材
として用いた場合、一定温度の熱エネルギーを安
定して吸収および放出するという潜熱型蓄熱材の
特徴を著しく損わせるものである。
酢酸ナトリウム３水和物CH3COONa.3H2Oは、
融解温度が58℃であり、潜熱量が51cal／ｇ（示
差走査熱量計による）と高いため、給湯用や暖房
用、更には恒温としての空調用などの潜熱型蓄熱
材として非常に有望であるが、この水和物の場合
にも過冷却現象がみられる。
即ち、一旦融解させた酢酸ナトリウム３水和物
は、約15℃前後の室温に放置しても固化しないの
である。これは、酢酸ナトリウム３水和物の凝固
開始温度が約−21℃であり、結局約80℃近い温度
差に相当する過冷却を生ずるためである。従つ
て、58℃における熱の吸収・放出が全く円滑に行
われないので、これ単独では蓄熱材として使用す
ることができない。
本発明者は、酢酸ナトリウム３水和物の過冷却
の程度を軽減させ得る発核剤を求めて種々検討の
結果、特定のリン酸のナトリウム塩が非常に有効
であることを見出した。
従つて、本発明は過冷却の程度を軽減させた潜
熱型の蓄熱材に係り、この蓄熱材は、酢酸ナトリ
ウム３水和物に発核剤としてリン酸二水素一ナト
リウム、リン酸三ナトリウムまたはこれらの混合
物を添加してなる。そして、これらのリン酸のナ
トリウム塩は、リン酸二水素一ナトリウム２水和
物またはリン酸三ナトリウム12水和物の如き水和
物であつてもよい。
過冷却軽減の程度は、用いられる発核剤の添加
割合によつても異なるが、あまり多くの発核剤を
添加しても期待される程の効果が得られないばか
りではなく、材料の変質をも招くため、一般に酢
酸ナトリウム３水和物に対し約0.1〜20重量％、
好ましくは約0.5〜10重量％の割合で用いられる。
過冷却軽減の程度は、蓄熱材の融解温度Tmと
凝固開始温度Tm′との差ΔTscによつて示される
が、酢酸ナトリウム３水和物に前記割合の発核剤
を加えることにより、ΔTscの値を顕著に低下せ
しめることができる。また、それに伴つて、融解
温度への復帰時間も短かくなり、熱サイクル試験
で長期にわたつて安定した性能を発揮することも
合まつて、より効率的な蓄熱作用を営むことがで
きる。
このようにして行われる酢酸ナトリウム３水和
物へのリン酸二水素一ナトリウムまたはリン酸三
ナトリウムの単独添加は、過冷却の程度の軽減に
有効であるが、これらを発核剤として添加した蓄
熱材は、発核作用を再現し得る高温時の環境温度
（この温度で加熱融解させたものを冷却凝固させ
る操作をくり返しても、再現性よく凝固し得る最
高加熱温度）が比較的低く、リン酸三ナトリウム
12水和物では92℃を示すものの、リン酸二水素一
ナトリウム２水和物では最高82℃であるにすぎな
い。
一般に、蓄熱材を各種用途に用いる場合、この
凝固再現可能な最高加熱温度を１℃でもあるいは
２℃でも高めることは、蓄熱材の信頼性を高める
上で重要なことである。その理由は、蓄熱材をそ
の温度以上に加熱すると発核剤の発核能力が消失
してしまうからであり、そのために蓄熱材の実際
の使用環境温度をそれ以下の温度に厳密に保持し
なければならないことになる。しかるに、その使
用環境温度を一定温度以下に抑えるためには複雑
なシステム制御が必要であり、これは現実には非
常に難かしい問題である。このために、実際の使
用時においては、凝固再現可能な最高加熱温度以
上の温度環境に蓄熱材が曝さられ、それの発核能
力が消失してしまう危険性が常に存在する。
従つて、このような最高加熱温度を少しでも高
めることができれば、比較的狭い温度範囲で使用
される蓄熱材の信頼性をかなり向上させることが
できるが、リン酸二水素一ナトリウムとリン酸三
ナトリウムの両者を約10〜40モル％：約90〜60モ
ル％の割合で併用して発核剤として添加すること
により、94℃という発核再現性最高加熱温度が得
られるようになる。
次に、実施例について本発明の効果を説明す
る。
実施例 １
酢酸ナトリウム３水和物に対し、それぞれ所定
割合のリン酸二水素一ナトリウム２水和物を添加
し、それらのΔTscの値を次の方法に従つて測定
した。
酢酸ナトリウム３水和物10ｇを容量20mlのガラ
ス容器にとり、それに発核剤の所定量を添加し、
密栓する。これを恒温槽内に入れ、上限温度80
℃、下限温度20℃の範囲内で、まず昇温速度１
℃／分にて加温し、それが融解する温度（Tm）
以上に混合物の温度を高めた後、今度は降温速度
１℃／分にて冷却し、ある温度（Tm′）迄過冷却
して固化するに至る熱サイクル試験をくり返して
行ない、その際の温度変化を熱電対で測定し、過
冷却の程度ΔTsc（Tm−Tm′）を調べた。得られ
た結果は、次の表１に示される。
The present invention relates to a heat storage material. More specifically, the present invention relates to a heat storage material that reduces the degree of supercooling during solidification and exhibits stable performance against long-term thermal cycles. Water and crushed stone have traditionally been used as heat storage materials, but because these have low heat storage densities (1 cal/g.deg or less), they require a fairly large heat storage device for practical use. Furthermore, as the heat is dissipated, the temperature inside the heat storage device gradually decreases, so it is technically quite difficult to obtain stable thermal energy. In response, research and development on applying the latent heat during melting and solidification of substances to heat storage has become active in recent years. A feature of such latent heat type heat storage materials is that they can stably absorb and release thermal energy at a constant temperature that matches the melting temperature of the material at a high heat storage density of several tens of cal/g. By the way, with recent advances in solar heat utilization technology and waste heat recovery technology, heat storage at relatively low temperatures of 50 to 60°C has been attracting attention as a heat source for hot water supply and space heating. Organic substances and inorganic hydrates such as paraffin wax and higher fatty acids are attracting attention as latent heat storage materials for storing heat at such low temperatures. Although organic materials as latent heat storage materials have good stability during melting and solidification, they have problems in absorbing and releasing heat because the material itself has poor thermal conductivity. Furthermore, since the specific gravity is small, the heat storage device becomes relatively large. On the other hand, inorganic hydrates have about twice the thermal conductivity as organic heat storage materials, and have a high specific gravity of about 1.5 to 2.0, so the heat storage device can also be made smaller.
However, inorganic hydrates generally exhibit a so-called supercooling phenomenon in which the solidification initiation temperature becomes lower than the melting temperature. Such a phenomenon, when an inorganic hydrate is used as a heat storage material, significantly impairs the characteristic of the latent heat type heat storage material that it stably absorbs and releases thermal energy at a constant temperature. Sodium acetate trihydrate CH 3 COONa.3H 2 O is
It has a melting temperature of 58°C and a high latent heat amount of 51 cal/g (measured by differential scanning calorimeter), so it is very promising as a latent heat storage material for hot water supply, space heating, and even air conditioning as a constant temperature. However, a supercooling phenomenon is also observed in the case of this hydrate. That is, once melted sodium acetate trihydrate does not solidify even if it is left at room temperature around 15°C. This is because the solidification initiation temperature of sodium acetate trihydrate is approximately -21°C, which results in supercooling corresponding to a temperature difference of approximately 80°C. Therefore, it cannot absorb and release heat at 58° C. smoothly, so it cannot be used alone as a heat storage material. The present inventor conducted various studies in search of a nucleating agent capable of reducing the degree of supercooling of sodium acetate trihydrate, and found that a specific sodium salt of phosphoric acid is very effective. Therefore, the present invention relates to a latent heat type heat storage material that reduces the degree of supercooling, and this heat storage material contains monosodium dihydrogen phosphate, trisodium phosphate, or trisodium phosphate as a nucleating agent in sodium acetate trihydrate. A mixture of these is added. These sodium salts of phosphoric acid may be hydrates such as monosodium dihydrogen phosphate dihydrate or trisodium phosphate dodecahydrate. The degree of supercooling reduction also depends on the addition ratio of the nucleating agent used, but adding too much nucleating agent will not only not produce the expected effect, but also cause deterioration of the material. Generally, about 0.1 to 20% by weight of sodium acetate trihydrate,
Preferably, it is used in a proportion of about 0.5 to 10% by weight. The degree of supercooling reduction is indicated by the difference ΔTsc between the melting temperature Tm and the solidification start temperature Tm' of the heat storage material. The value can be significantly reduced. In addition, as a result, the time required to return to the melting temperature is shortened, and stable performance is exhibited over a long period of time in thermal cycle tests, making it possible to perform a more efficient heat storage function. Adding monosodium dihydrogen phosphate or trisodium phosphate alone to sodium acetate trihydrate in this manner is effective in reducing the degree of supercooling, but adding these as nucleating agents The heat storage material has a relatively low environmental temperature at a high temperature that can reproduce the nucleation effect (the maximum heating temperature at which the material can be solidified with good reproducibility even if the operation of cooling and solidifying the material heated and melted at this temperature is repeated). trisodium phosphate
Although the dodecahydrate shows a temperature of 92°C, the maximum temperature for monosodium dihydrogen phosphate dihydrate is only 82°C. Generally, when a heat storage material is used for various purposes, it is important to increase the maximum heating temperature at which solidification can be reproduced by even 1°C or 2°C in order to improve the reliability of the heat storage material. The reason for this is that if the heat storage material is heated above that temperature, the nucleating ability of the nucleating agent will be lost, so the actual operating environment temperature of the heat storage material must be kept strictly below that temperature. It will happen. However, in order to keep the operating environment temperature below a certain temperature, complicated system control is required, which is a very difficult problem in reality. For this reason, during actual use, there is always a risk that the heat storage material will be exposed to a temperature environment higher than the maximum heating temperature at which solidification can be reproduced, and that its nucleating ability will be lost. Therefore, if the maximum heating temperature could be increased even a little, the reliability of heat storage materials used in a relatively narrow temperature range could be considerably improved, but monosodium dihydrogen phosphate and trisodium phosphate By adding both sodium as a nucleating agent in a ratio of about 10 to 40 mol %: about 90 to 60 mol %, a maximum reproducible nucleation heating temperature of 94° C. can be obtained. Next, the effects of the present invention will be explained with reference to Examples. Example 1 A predetermined proportion of monosodium dihydrogen phosphate dihydrate was added to sodium acetate trihydrate, and their ΔTsc values were measured according to the following method. Place 10 g of sodium acetate trihydrate in a 20 ml glass container, add a predetermined amount of nucleating agent to it,
Seal tightly. Place this in a constant temperature bath, and the upper limit temperature is 80.
℃, within the range of lower limit temperature 20℃, temperature increase rate 1
Temperature at which it melts when heated at °C/min (Tm)
After raising the temperature of the mixture above, the mixture was cooled at a cooling rate of 1°C/min, and a thermal cycle test was repeated to supercool and solidify to a certain temperature (Tm'), and the temperature at that time was The change was measured with a thermocouple, and the degree of supercooling ΔTsc (Tm - Tm') was investigated. The results obtained are shown in Table 1 below.
【表】
過冷却防止の効果は、長期のくり返しにおい
て、安定に発揮されなければならない。上記表１
の結果は、20サイクル目の値であるが、初回から
その効果は変らず、50サイクル後においても安定
している。添加割合が20重量％以上になると、酢
酸ナトリウム３水和物本来の融解温度（Tm）よ
りも、蓄熱材としての融解温度が著しく低下し、
50〜60℃の必要温度範囲を満足させない結果とな
る。こうした結果から、添加割合の上限は約20重
量％である。こうした一連の傾向は、リン酸二水
素一ナトリウムの無水物を用いた場合にも同様で
ある。
なお、No.３の場合における熱サイクル試験の経
時的な温度変化が、第１図のグラフに示されてい
る。
実施例 ２
酢酸ナトリウム３水和物に対し、１重量％のリ
ン酸三ナトリウム12水和物を添加し、それの20サ
イクル目の値を測定すると、ΔTsc＝5deg、Tm
＝58℃であつた。
実施例 ３
酢酸ナトリウム３水和物10ｇに、発核剤として
リン酸二水素一ナトリウム２水和物およびリン酸
三ナトリウム12水和物を合計３モル％加えたもの
を、容量20mlのガラス容器にとり、密栓する。こ
れを80℃の恒温槽中に４時間浸漬し、試料を完全
に融解させた後室温に放置する。試料は過冷却を
生じ、室温に達しても液体状態を保つているが、
この過冷却状態にある融液に微量の酢酸ナトリウ
ム３水和物を加え、固化させた。
以上のような固化処理を行なつた後、試料をそ
れぞれ所定温度の恒温槽中に２時間浸漬して加熱
融解させ、融解させた試料を室温に放置して、そ
の固化状態を観察した。５回くり返して行われた
試験結果は、次の基準に従つて評価された。
○：すべての場合において再現性よく固化した
△：発核能力が喪失する場合もあつた
×：全く固化しなくなる[Table] The effect of preventing supercooling must be demonstrated stably over a long period of time. Table 1 above
Although the result is the value at the 20th cycle, the effect remains unchanged from the first time and remains stable even after 50 cycles. When the addition ratio is 20% by weight or more, the melting temperature as a heat storage material is significantly lower than the original melting temperature (Tm) of sodium acetate trihydrate,
The result is that the required temperature range of 50 to 60°C is not satisfied. Based on these results, the upper limit of the addition ratio is about 20% by weight. This series of trends is the same when anhydrous monosodium dihydrogen phosphate is used. Incidentally, the temperature change over time in the thermal cycle test in case No. 3 is shown in the graph of FIG. Example 2 When 1% by weight of trisodium phosphate dodecahydrate was added to sodium acetate trihydrate and the value at the 20th cycle was measured, ΔTsc = 5deg, Tm
= 58℃. Example 3 A total of 3 mol% of monosodium dihydrogen phosphate dihydrate and trisodium phosphate dodecahydrate were added as nucleating agents to 10 g of sodium acetate trihydrate in a glass container with a capacity of 20 ml. Take it and seal it tightly. This is immersed in a constant temperature bath at 80°C for 4 hours to completely melt the sample, and then left at room temperature. The sample undergoes supercooling and remains in a liquid state even after reaching room temperature.
A trace amount of sodium acetate trihydrate was added to this supercooled melt to solidify it. After performing the solidification treatment as described above, each sample was immersed in a constant temperature bath at a predetermined temperature for 2 hours to heat and melt, and the melted sample was left at room temperature to observe its solidification state. The test results, which were repeated five times, were evaluated according to the following criteria. ○: Solidified with good reproducibility in all cases △: Nucleation ability was lost in some cases ×: No solidification at all
【表】
以上の結果から、リン酸三ナトリウム12水和物
が発核剤混合物中約60〜90モル％の範囲内で用い
られたとき、94℃の環境温度においても、再現性
よく固化することが分る。このような傾向は、発
核剤の添加量が酢酸ナトリウム３水和物に対し約
0.1重量％以上で成立するが、約20重量％以上に
なると、酢酸ナトリウム３水和物の本来の融解温
度である58℃に対し、蓄熱材の融解温度が50℃以
下となつてしまい目的とする蓄熱温度範囲からは
ずれるようになる。なお、上記のような環境温度
の再現性は、リン酸二水素一ナトリウムおよびリ
ン酸三ナトリウムの無水物を用いた場合にも得ら
れる。
このように、酢酸ナトリウム３水和物への発核
剤の添加は、過冷却を有効に防止し得るが、発核
剤に加えて水を系中に共存させると、安定した融
解・凝固がくり返され、即ちより安定した蓄熱作
用の営まれることが判明した。
第２図は、CH3COONa―H2Oの２成分系平衡
線図である。ここで、
ラインＣ―Ｂ―Ｄ―Ｆ：CH3COONa・3H2O
の固相と水溶液との２相が存在する領域
ラインＡ―Ｂ―Ｄ―Ｅ：CH3COONaの固相と
水溶液との２相が存在する領域
ラインＦ―Ｄ―Ｅ ：CH3COONa・3H2O
の固相とCH3COONaの固相とが存在する
領域
ところで、実際にCH3COONa・3H2Oを蓄熱
材に用いる場合には、発核剤の添加により過冷却
が防止されるが、ラインＫ―Ｄの存在、即ち無水
のCH3COONaが析出するということは、蓄熱器
の熱交換において伝熱の効率を低下させ、更には
蓄熱器内にスラツジを堆積させ、これにより蓄熱
材本来の性能ばかりか蓄熱器の性能をも低下させ
るおそれがある。
本発明においては、かかる無水のCH3COONa
の析出による性能低下がみられる場合には、発核
剤に加えて水を添加し、２成分系平衡図における
点Ｂ付近の組成になるように調整することが有効
である。この目的のために添加される水の量は、
CH3COONa・3H2Oに対して約10重量％以下、
好ましくは約２〜５重量％である。これ以上の割
合で水を添加すると、融解温度が本来の材料のそ
れよりも著しく低下するばかりでなく、潜熱量の
低下もひき起される。そして、このような範囲内
での水の添加は、発核剤の発核作用を何ら妨げる
ものではなく、依然有効な融解・凝固サイクルが
営まれる。なお、これとは反対に、無水の
CH3COONaなどの添加など蓄熱材の水分量を減
少させることは、無水物の析出を増加させるため
好ましくない。
かかる態様の実施例を、更に追加する。
実施例 ４
実施例１，No.４の材料に、更に水を0.38ｇ添加
する。この材料は、酢酸ナトリウムの58重量％水
溶液の組成に相当するもので凝固に際しては、無
水酢酸ナトリウムの析出をみることなく、ΔTsc
＝5degにて固化した。また、50回の熱サイクル
試験に対しても、凝固の挙動は何ら変らず、安定
した融解・凝固がくり返されることが確認され
た。[Table] From the above results, when trisodium phosphate dodecahydrate is used within the range of approximately 60 to 90 mol% in the nucleating agent mixture, it solidifies with good reproducibility even at an environmental temperature of 94°C. I understand. This tendency can be seen when the amount of nucleating agent added is approximately
This is true at 0.1% by weight or more, but if it exceeds about 20% by weight, the melting temperature of the heat storage material will be 50°C or lower, compared to the original melting temperature of sodium acetate trihydrate, which is 58°C, and it will not meet the purpose. The heat storage temperature range falls outside of the specified heat storage temperature range. Note that the reproducibility of the environmental temperature as described above can also be obtained when anhydrous monosodium dihydrogen phosphate and trisodium phosphate are used. As described above, adding a nucleating agent to sodium acetate trihydrate can effectively prevent supercooling, but if water is coexisting in the system in addition to the nucleating agent, stable melting and solidification may not be achieved. It has been found that a more stable heat storage effect can be carried out over and over again. FIG. 2 is a two-component system equilibrium diagram of CH 3 COONa-H 2 O. Here, line C-B-D-F: CH 3 COONa・3H 2 O
Area where two phases of solid phase and aqueous solution exist Line A-B-D-E: Area where two phases of CH 3 COONa solid phase and aqueous solution exist Line F-D-E: CH 3 COONa・3H 2 O
A region where a solid phase of The presence of K-D, that is, the precipitation of anhydrous CH 3 COONa, reduces the efficiency of heat transfer in the heat exchange of the heat storage device, and also causes sludge to accumulate in the heat storage device, thereby destroying the original properties of the heat storage material. There is a risk that not only the performance but also the performance of the heat storage device will be deteriorated. In the present invention, such anhydrous CH 3 COONa
If performance deterioration is observed due to precipitation of , it is effective to add water in addition to the nucleating agent and adjust the composition to be near point B in the two-component system equilibrium diagram. The amount of water added for this purpose is
Approximately 10% by weight or less based on CH 3 COONa・3H 2 O,
Preferably it is about 2-5% by weight. Addition of water in proportions greater than this not only causes the melting temperature to be significantly lower than that of the original material, but also causes a decrease in the amount of latent heat. Addition of water within this range does not impede the nucleating action of the nucleating agent, and an effective melting/solidification cycle can still be carried out. However, on the contrary, anhydrous
Reducing the water content of the heat storage material by adding CH 3 COONa or the like is not preferable because it increases the precipitation of anhydride. Further examples of such aspects will be added. Example 4 0.38 g of water is further added to the material of Example 1, No. 4. This material corresponds to the composition of a 58% by weight aqueous solution of sodium acetate, and upon solidification, no precipitation of anhydrous sodium acetate was observed, and ΔTsc
Solidified at =5deg. Furthermore, it was confirmed that there was no change in solidification behavior even after 50 thermal cycle tests, and stable melting and solidification were repeated.
第１図は、実施例１のNo.３の場合における熱サ
イクル試験の経時的な温度変化を示すグラフであ
る。また、第２図は、CH3COONa―H2Oの２成
分系平衡線図である。
符号の説明、Ｌ：液相、S1：CH3COONaの固
相、S2：CH3COONa・3H2Oの固相。
FIG. 1 is a graph showing the temperature change over time in the thermal cycle test in case No. 3 of Example 1. Moreover, FIG. 2 is a two-component system equilibrium diagram of CH 3 COONa-H 2 O. Explanation of symbols, L: liquid phase, S 1 : solid phase of CH 3 COONa, S 2 : solid phase of CH 3 COONa.3H 2 O.
Claims (1)
ン酸二水素一ナトリウム、リン酸三ナトリウムま
たはこれらの混合物を添加してなる蓄熱材。 ２ リン酸のナトリウム塩が水和物である特許請
求の範囲第１項記載の蓄熱材。 ３ 酢酸ナトリウム３水和物に対し発核剤が約
0.1〜20重量％の割合で添加された特許請求の範
囲第１項記載の蓄熱材。 ４ 酢酸ナトリウム３水和物に対し、更に水が約
10重量％以下の割合で添加された特許請求の範囲
第１項記載の蓄熱材。 ５ 加熱目的に用いられる特許請求の範囲第１項
記載の蓄熱材。[Claims] 1. A heat storage material obtained by adding monosodium dihydrogen phosphate, trisodium phosphate, or a mixture thereof as a nucleating agent to sodium acetate trihydrate. 2. The heat storage material according to claim 1, wherein the sodium salt of phosphoric acid is a hydrate. 3 The nucleating agent for sodium acetate trihydrate is approximately
The heat storage material according to claim 1, wherein the heat storage material is added in a proportion of 0.1 to 20% by weight. 4 Approximately more water is added to sodium acetate trihydrate.
The heat storage material according to claim 1, wherein the heat storage material is added in a proportion of 10% by weight or less. 5. The heat storage material according to claim 1, which is used for heating purposes.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1245783A JPS59138290A (en) | 1983-01-28 | 1983-01-28 | Heat-accumulation material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1245783A JPS59138290A (en) | 1983-01-28 | 1983-01-28 | Heat-accumulation material |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS59138290A JPS59138290A (en) | 1984-08-08 |
| JPH0215598B2 true JPH0215598B2 (en) | 1990-04-12 |
Family
ID=11805870
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1245783A Granted JPS59138290A (en) | 1983-01-28 | 1983-01-28 | Heat-accumulation material |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS59138290A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10237434A (en) * | 1997-02-28 | 1998-09-08 | Sumika Plast Kk | Production of heat storage material |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3411399A1 (en) * | 1984-03-28 | 1985-10-10 | Philips Patentverwaltung Gmbh, 2000 Hamburg | LATENT HEAT STORAGE, METHOD FOR PRODUCING A NUCLEAR IMAGER AND LATENT HEAT STORAGE |
| JPH07103365B2 (en) * | 1987-06-19 | 1995-11-08 | エヌオーケー株式会社 | Pretreatment method for heat storage material |
| DE10136487A1 (en) * | 2001-07-27 | 2003-02-13 | Merck Patent Gmbh | Heat-storage medium used in e.g. latent heat storage and hot water storage, contains sodium acetate-trihydrate as phase change material, and a mixture of alkali metal hydrogen phosphates and/or their hydrates as nucleating agents |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57153079A (en) * | 1981-03-17 | 1982-09-21 | Matsushita Electric Ind Co Ltd | Supercooling inhibitor and preparation thereof |
-
1983
- 1983-01-28 JP JP1245783A patent/JPS59138290A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57153079A (en) * | 1981-03-17 | 1982-09-21 | Matsushita Electric Ind Co Ltd | Supercooling inhibitor and preparation thereof |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10237434A (en) * | 1997-02-28 | 1998-09-08 | Sumika Plast Kk | Production of heat storage material |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS59138290A (en) | 1984-08-08 |
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